MXene‐Based Piezoelectric and Triboelectric Energy Harvesters for Personalized Monitoring and Therapeutics

ABSTRACT

MXenes, a rapidly expanding family of two‐dimensional transition‐metal carbides and nitrides, have emerged as a key material of self‐powered wearable electronics and therapeutics owing to their metallic conductivity, mechanical flexibility, and highly tunable surface chemistry. Their integration into piezoelectric nanogenerators and triboelectric nanogenerators (PENGs and TENGs) has substantially advanced mechanical‐to‐electrical energy conversion in flexible, skin‐conformal devices. This review critically examines recent progress in MXene‐enabled nanogenerators, covering material synthesis, device architectures, charge‐generation mechanisms, and system‐level integration. Emphasis is placed on emerging MXene‐based composites, including hydrogels, aerogels, nanofibers, and smart textiles, that synergistically integrate energy harvesting, sensing, and mechanical robustness for continuous physiological monitoring, human–machine interfaces, sports analytics, wearable therapeutics and in vivo applications. Key challenges limiting practical deployment, such as oxidation instability, mechanical fatigue, biocompatibility, and scalable manufacturing, are systematically analyzed alongside state‐of‐the‐art mitigation strategies. Finally, future perspectives are outlined, highlighting the convergence of MXene nanogenerators with artificial intelligence, the Internet of Things, and sustainable materials systems to enable autonomous, intelligent, and next‐generation, personalized monitoring and therapeutic technologies.

The graphical abstract illustrates MXene‐enabled self‐powered wearable systems, highlighting piezoelectric and triboelectric nanogenerators integrated into health monitoring, smart textiles, human–machine interfaces, sports applications, and in vivo therapeutics.

1. Introduction

Advanced personalized monitoring and therapeutics technologies are transforming the medical landscape by enabling continuous monitoring of critical physiological parameters, including pulse rate, electrocardiography (ECG), respiratory patterns, heart sound and endovascular motion [1, 2, 3]. Beyond diagnostics, these systems play a critical role in guiding timely therapeutic interventions, facilitating early disease detection, enabling treatment personalization, and enabling closed‐loop healthcare solutions. Their clinical value is further enhanced by their compact form factor, user‐friendly design, mechanical stretchability, and portability, which collectively enable long‐term, comfortable use in both clinical and home‐based settings [4]. However, their long‐term viability and performance are fundamentally constrained by limited battery life and frequent recharging. These limitations have prompted scientists to develop new solutions that can maintain flexibility, wearability, and accuracy for continuous monitoring without relying on bulky batteries [5]. To address these challenges, self‐powered personalized monitoring and therapeutic technologies have emerged as a promising solution, capable of autonomously harvesting biomechanical energy from natural human motion. These systems eliminate the reliance on conventional power sources, thereby enabling long‐term, continuous operation of wearable and implantable devices [6, 7]. Among the various energy‐harvesting approaches, nanogenerators have emerged as a key enabling technology and are actively being developed to power next‐generation personalized monitoring and therapeutic platforms [8].

Piezoelectric nanogenerators (PENGs) convert mechanical stress into electrical energy [9]. Zhong Lin Wang introduced the first PENGs in 2006, utilizing zinc oxide (ZnO) to convert mechanical energy to electrical power, thereby demonstrating the feasibility of harvesting ambient mechanical energy [10]. Concurrently, triboelectric nanogenerators (TENGs) work through a combination of contact‐based charge generation and electrostatic induction between dissimilar materials [11]. Since the first introduction of TENG by Wang et al. in 2012 [12]. The field of triboelectric nanogenerators (TENGs) has advanced rapidly in recent years, driven by intensive efforts to improve device efficiency, electrical output, and long‐term operational stability. The performance of TENG devices is governed by multiple factors, including device architecture, surface morphology, functionalization, contact force, and the selection of triboelectric materials [13, 14]. Although many triboelectric materials are abundant, optimizing their properties through physical, chemical, and hybrid strategies remains a significant challenge [15]. Ultimately, PENGs and TENGs offer a promising pathway to resolving the energy‐autonomy problem for wearable devices, enabling sustainable, long‐term operation [16].

A wide array of nanomaterials, including organic and inorganic structures, has attracted significant interest for self‐powered nanogenerator‐based personalized monitoring and therapeutics devices [13, 17, 18]. Nevertheless, persistent challenges in achieving high performance and accuracy have stimulated the exploration of next‐generation materials, particularly two‐dimensional structures (2D) and layered nanomaterials [19]. Among these, MXenes have emerged as the leading candidates owing to their unprecedented electrical conductivity, robust mechanical strength, and highly tunable surface chemistry [20].

MXenes, a class of 2D materials with the general formula M_n+1X_nT_x, are typically synthesized by selectively etching the ‘A’ layer from MAX phases. With a graphene‐like morphology, the MXene material family now comprises more than 30 experimentally realized compositions, with many more predicted theoretically [21]. Their distinctive characteristics make them highly effective for thermal management, energy storage, personalized wearable electronics, and therapeutics [22]. Specifically, integrating MXenes into piezoelectric nanogenerators (PENGs) enhances device performance by improving electrical conductivity and increasing the effective contact area [23]. MXene‐based nanocomposites can be used to create flexible, durable devices that effectively harness kinetic energy, making them ideal materials for self‐powered sensors and electronics [24]. Following the first demonstration of MXene‐based triboelectric nanogenerators (TENGs) in 2017, MXenes have been shown to serve as adaptable components, including triboelectric layers, electrodes, and electron‐trapping surfaces, thereby enhancing device performance [25, 26]. Their high conductivity, coupled with a layered structure and tunable surface chemistry, facilitates superior charge transport, enhances dielectric properties, and improves mechanical flexibility [27, 28]. These advantages make MXenes highly promising materials for developing efficient, robust, and versatile TENGs, opening new avenues for sophisticated self‐powered personalized wearable monitoring and therapeutic technologies [29, 30].

Several recent reviews demonstrate the growing application of MXenes in advanced sensing and energy‐harvesting technologies. For example, a review by Atkare et al. [31] highlighted the utility of MXenes in self‐powered ammonia gas sensors, where MXenes enhance surface functionality and electrical conductivity. Meanwhile, Deng et al. [32] provided a comprehensive overview of MXene‐enhanced triboelectric nanogenerators (TENGs), covering their structural design, fabrication techniques, and versatile functions. Building on this, Rasheed et al. [33] critically examined both piezoelectric and triboelectric nanogenerators (PENGs and TENGs) incorporating MXene materials, focusing on performance metrics, synthesis‐property relationships, and limitations to guide future research and commercialization. All these reviews have provided in‐depth discussions of MXenes for energy storage and hybrid devices, or have focused on TENG principles and their applications in biomedical wearables and soft robotics. However, this review summarizes recent advancements in MXene‐integrated PENG and TENG devices, providing a comparative analysis of their working principles, sensing mechanisms, and architectural designs. Applications are surveyed across key domains, including smart healthcare, sports analytics, electronic skins, intelligent systems, therapeutics and in vivo applications.

Furthermore, this review critically evaluates the key challenges that hinder real‑world implementation of MXene‑based piezoelectric and triboelectric nanogenerators, including long‑term operational stability, biocompatibility, and the scalability of fabrication strategies. It then outlines emerging opportunities, such as the integration of artificial intelligence (AI), sustainable and green fabrication approaches, and the development of multifunctional, application‑ready platforms. As schematically illustrated in Figure 1, this analysis provides a comprehensive overview of MXene development and its relevance to energy harvesting and self‑powered wearable healthcare technologies. Specifically, Figure 1I depicts the fundamental operating principles of MXene‑enabled PENGs and TENGs and their roles in energy harvesting, sensing, and diverse wearable applications, including health monitoring, human–machine interfaces, smart textiles, sports tracking, and in vivo therapeutics. Figure 1II compares top‑down and bottom‑up MXene synthesis routes, emphasizing surface chemistry control and scalable fabrication. Figure 1III summarizes the historical evolution of MXenes, from MAX phase discovery to the rapid expansion of MXene families and their applications in advanced self‑powered systems.

FIGURE 1.

Overview of MXene evolution, synthesis strategies, and applications in piezoelectric and triboelectric nanogenerators.

2. Overview of MXene and Its Relevance to Wearable Electronics

MXenes are a diverse family of two‐dimensional compounds comprising transition‐metal carbides and nitrides, which are characterized by outstanding electrical, mechanical, and chemical properties [34]. The initial synthesis of MXenes in 2011, which involved selectively etching Ti₃AlC₂ with hydrofluoric acid to form Ti₃C₂ MXene, paved the way for the rapid discovery of a vast library of similar materials [21]. MXenes are generally represented by the formula M_{n + 1}X_nT_x, where M represents an early transition metal, X denotes carbon and/or nitrogen, and T includes surface functional groups, such as ‐O, ‐OH, ‐F, and ‐Cl or ‐S that are introduced during the synthesis process (Figure 2I) [35].

FIGURE 2.

Overview of MXene elements and MAX phases. (I) Important elemental constituents of MAX phases and resultant MXenes, including transition metals, carbon or nitrogen layers, A‐group elements, and surface functional groups. The schematic also shows which compositions have been successfully synthesized and are still restricted to MAX precursors. Reproduced with permission [35]. Copyright 2024, Elsevier B.V. (II) MAX phases, and MXenes (n = 1–4), with transition metals, X elements (C/N), A‐group layers, and surface terminations indicated. The known MXene compositions are referred to as gradient shading; known MXene‐constraining phases that have not been converted to MXenes are referred to as Mn bars. Reproduced with permission [36]. Copyright 2021, Wiley‐VCH GmbH.

The conventional synthesis of MXenes employs a top‐down approach, where the ‘A’ layer of the parent MAX phases is selectively etched away using HF (or less harsh alternatives, such as LiF‐HCl). Subsequent delamination and exfoliation yield few‐ or single‐layered MXene flakes [21]. The selection of the etchant and post‐treatment conditions critically determines both the surface chemistry and the final structural properties of the product. As an example, HF etching typically yields a mixture of ‐O, ‐OH, and ‐F terminations, as shown in Figure 2II, whereas molten‐salt synthesis routes produce ‐Cl‐ or ‐Br‐terminated surfaces. The compositional and functional versatility of MXenes can be further expanded through post‐synthetic modification, enhancing their suitability for diverse applications [36].

The latest developments in MAX phase chemistry have led to the synthesis of intricate MAX phases, including those with bi‐transition metals or in‐plane/out‐of‐plane configurations, which generate vacancy order, thereby facilitating the identification of MXenes with tunable properties [37]. The possibility of synthesizing MXenes has been further broadened to include high‐entropy and solid‐solution MAX phase derivatives. Although carbide‐based MAX phases are currently dominant in research, efforts are underway to develop nitride and carbonitride MAX phases, which pose a challenge due to their chemical instability during etching reactions. In addition, non‐MAX precursors, as well as bottom‐up approaches such as chemical vapor deposition and salt‐templating, have been investigated further to expand MXene structural diversity [37, 38].

The metallic or near‐metallic conductive behavior of MXenes is due to the overlapping d‐orbitals of transition metals across M‐X layers, which facilitate the in‐plane movement of electrons [39]. MXenes exhibit a rich array of surface functional groups, offering tunable functional characteristics, superior charge accumulation, and improved interfacial interactions with various materials. This makes MXene highly suitable for piezo‐ and triboelectric nanogenerators that rely on its surface chemistry and charge‐transfer capabilities [40].

Mechanically, the layered nature of MXenes provides exceptional flexibility and mechanical toughness. The capability for interlayer slippage and deformation enables MXenes to maintain their superior electrical performance during multiple folding, elongation, and compression, all of which are necessary for skin‐mounted electronics and therapeutics [41]. In addition, the natural intercalation of various ions and molecules in the space between MXene layers facilitates precise control of the interlayer spacing, thereby affecting ion transport and the capacitive and mechanical softness characteristics of the materials, which is critical for wearable energy storage and electro‐sensing applications [42, 43].

Compared to other 2D materials, such as graphene and MoS₂, the conductivity and surface chemistry in MXenes can be made near‐metallic and highly controllable, respectively. Although the absence of surface groups makes graphene less preferable for advanced conduction and high mechanical performance, MoS₂ is semiconducting with low conductivity. This unique property enables MXenes to fill the performance gap of other 2D materials, making them extremely versatile for energy harvesting and sensing applications [44, 45].

Therefore, MXenes have been effectively deployed for energy harvesting in both triboelectric nanogenerators (TENGs) [21] and piezoelectric nanogenerators (PENGs) [26], exhibiting high electronegativity that promotes triboelectric charge generation, while their high dielectric constant and layered structure support efficient charge trapping and retention. In TENGs, MXenes improve both the triboelectric and electrode layers, offering high conductivity, mechanical durability, and compatibility with flexible substrates. These properties enable stable, high‐performance operation in wearable and self‐powered devices [46, 47].

2.1. Challenges and Future Perspective of MXene

2.1.1. Oxidation and Environmental Instability

Oxidation of MXenes is an inherent property when they are exposed to air and moisture, and it is a major constraint on their performance and applications. The reason for oxidation lies in their highly specific surface area, two‐dimensional structure, and the chemical reactivity of the surface groups (O, OH, and F) formed through the etching procedure [48].

The oxidation of MXenes generally begins at their surface and edge defects, where oxygen molecules readily adsorb and diffuse into the interlayer spaces. This causes progressive oxidation of the transition‐metal carbides and/or nitrides to metal oxides, such as TiO₂ in the case of Ti₃C₂T_x, along with the breaking of the M–X bonding network [49]. This process profoundly influences the properties of MXenes. From a structural point of view, it leads to the degradation of the flakes into smaller pieces and a loss of structural stability, while from an electronic point of view, there is a sharp decrease in electrical conductivity owing to the transition from metallic to insulator‐like phases in MXenes. This significantly affects the performance of energy harvesting devices, including reduced charge‐transfer efficiency, poor sensing capabilities, and unstable energy generation [50].

To overcome these problems, many techniques have been employed, including surface passivation, polymer encapsulation, antioxidants, layer modification, and storage of the material in an inert or low‐temperature environment [51]. Although these methods have shown some success in providing the necessary stability, maintaining environmental stability without affecting MXene's electrical and mechanical properties remains an area of ongoing research [52].

Researchers have actively explored different strategies to enhance MXene stability. For instance, Wu et al. reported an in‐situ capping method with sodium ascorbate (SA), which significantly improved the oxidation resistance, enabling the materials to remain stable for more than 80 days without any conductivity loss. Wu et al.’s approach also enabled the development of printable SA‐MXene inks for fabricating high‐performance micro‐supercapacitors [53]. Similarly, Lee et al. showed that hydrogen annealing is a useful method to enhance oxidation stability under vigorous conditions (100% RH, 70 °C), restore conductivity in formerly oxidized films, and enable robust functioning in humid conditions [54]. Habib et al. performed a systematic examination of oxidation rates in air, liquid, and solid phases. They found that oxidation was more rapid in the liquid phase and that visual indicators (e.g., color change) were unreliable [55]. In another approach, Qian et al. proposed a nano‐armoring scheme in which a thin layer of copper was deposited on the MXene surfaces, creating an MXene@Cu heterostructure with high conductivity (1.17 × 10⁶ S m⁻¹), mechanical strength, and oxidation resistance. These developments highlight the importance of surface engineering and protective coatings for improving MXene stability in practical applications [56].

Cui et al. proposed a tannic acid‐modified MXene composite film that enhances oxidation resistance and imparts very low emissivity. The authors have stated that TA decreases pore size, aligns nanosheets, and preferentially reacts with H₂O/O₂ to form a protective coordination layer on Ti atoms. Consequently, the composite exhibited an emissivity below 0.24, maintaining its effective stealth performance even after 20 days of operation under hot, humid conditions. In contrast, the pristine MXene films decayed within minutes. This study presents an effective strategy to improve MXene stability in harsh conditions without compromising its intrinsic functional properties [57].

To explain the oxidation mechanism of MXene, Tian et al. proposed a nucleophilic attack of water on surface metal atoms similar to an Sn₂ reaction. Through constant‐potential ab initio simulations, they demonstrated that, when the oxidizing agent‐ oxygen of the water molecule‐attacks the nucleophilic metal atoms from above, this reaction leads to the creation of metal hydroxyl lumps; these latter species destabilize the MXene surface. They observed similar behavior for MBenes, suggesting the prevalence of Walden inversion‐like mechanisms in the molecular reconstruction of these 2D materials. More specifically, AIMD simulations of V₂CO₂ in pure water indicated that the oxidation process first started at ∼1.43 ps and proceeded due to deprotonation of the V atoms to create V‐OW and V‐OWH structures (Figure 3Ia,c). This process is faster in an oxygen‐deficient environment (∼0.556 ps), where exposed V atoms are further oxidized by O₂, leading to the formation of vacancies (Figure 3I‐b). Accordingly, energy analyses identified water attack, O₂ interaction, and vacancy formation as the three sequential steps in the degradation process. In this work, an atomistic insight into MXene instability has been provided, and this work might serve as a foundation for future MXene design with higher oxidation resistance [58].

FIGURE 3.

Mechanical and Operation Stability of MXene (I) Sample images in unconstrained ab initio molecular dynamics (AIMD) simulations of the oxidation of V₂CO₂ MXene. (a) In a pure water environment, water molecules undergo nucleophilic attack on the surface vanadium atoms, leading to a structural change. (b) Oxidation is more intense in an oxygen‐rich environment due to the interaction between water and oxygen. (c) Structural representation of the major oxidation processes, such as water attack, deprotonation, and Walden inversion. Color coding: Atom colors vanadium (purple), carbon (brown), oxygen (red), and hydrogen (white). Reproduced under Creative Commons 4.0 License [58]. Copyright 2024, Springer Nature. (II) (a) Visual representation of dense bridging: (i) Schemes: ice‐templated assembly of MXene sheets can allow the alignment of the sheets with the cellulose nanocrystals (CNC) through hydrogen bonds, creating reduced spacing between the sheets and enhancing the orientation of the structure. (ii‐iii) (ii) Schemes: Salting‐out effect The salting‐out effect facilitated aggregation of MXene sheets as they accumulate around the cellulose nanocrystals (CNC), which form nano sheets that (b) Salting‐out in dense bridging mechanisms: (b1) The hydration water of a material and its hydration shell are polarized by specific anions and hydrogen bonds between the material and the hydration shell are broken. (b2) Phase separation and reduced solubility are caused by interference of certain anions with hydrophobic hydration. Reproduced with permission [59]. Copyright 2024, American Chemical Society.

2.1.2. Mechanical and Operational Stability

MXenes are inherently flexible 2D materials, but retaining mechanical and operational stability is highly challenging. The problem arises from the material's ultrathin, stacked structure, which contributes to its flexibility but also makes it susceptible to structural breakdown during mechanical operations such as bending, stretching, torsion, and compression [60]. Additionally, the relatively weaker van der Waals forces and the possibility of water molecules or ions between layers may cause slippage, delamination, or cracking [61].

Operational instability is compounded when devices are exposed to environmental conditions encountered in wearable and therapeutic devices, such as sweating, high humidity, temperature variations, and biomolecular entities [62]. These environmental factors can result in unstable interlayer distances and weakened interfacial bonding between MXene layers, altering the charge‐transfer path and surface charge density, leading to drifting of the generated signals and fluctuating output [63]. Operationally, over the long term, mechanical fatigue and environmental factors degrade the electrical behavior of these devices. For instance, triboelectric and piezoelectric nanogenerators experience a reduction in resistance and sensitivity due to wear and tear, as well as poor charge storage caused by interfacial bonding [64, 65].

Overcoming such issues requires proper mechanical and interface engineering, including incorporating MXenes into stretchable polymer matrices, modifying their surfaces to improve layer cohesion, and adopting encapsulation methods to protect devices from environmental exposure [66]. Realistic wearability and therapeutic conditions demand that composite systems based on MXenes be mechanically resilient and reliable to ensure widespread applicability [67].

To address the above issues, scientists have devised various strategies to enhance the stability and mechanical strength of MXene [63]. For example, Ye et al. demonstrated the high efficiency of using controlled defects, achieved by incorporating Ti₃C₂Tx MXene flakes and encapsulating them with MgO, to enhance the toughness of Ti₃C₂Tx/ZK61 composites. The engineered defects within the flakes enabled coordinated dislocation motion, thereby slowing crack development and enhancing both compressive strength and failure strain accordingly [68]. To optimize the rheological properties of Ti₃C₂T_x solutions, Li et al. incorporated multivalent metal cations, which induced ionic cross‐linking and yielded fiber‐like gels with high electrical and ionic conductivity, opening the door to wearable applications [69].

Cai et al. fabricated a triboelectric MXene/cellulose nanocrystal (CNC) aerogel with enhanced mechanical strength using a dense‐bridging approach induced by the salting‐out effect. An ice‐templating technique facilitated hydrogen bonding between the MXene sheets and CNC, resulting in an ordered, layered network structure (Figure 3II‐a‐i). The structural optimization promoted stronger interfaces between the MXene and cellulose chains and inhibited nanosheet slip and enhanced the alignment of the nanosheets (Figure 3II‐a‐ii,iii). Such structural optimization increased energy dissipation and compressive resistance. The salting‐out effect is proposed to operate via two mechanisms: (1) certain anions polarize the hydration water, breaking the hydrogen bonds between the material and its hydration shell (Figure 3II‐b1); and (b2) different ions disrupt hydrophobic hydration, reducing solubility and thereby causing phase separation. These structurally engineered properties provide the aerogel with excellent mechanical and triboelectric properties, representing a promising approach to creating durable, versatile energy‐harvesting materials [59].

Zhang et al. also used the Hofmeister effect and directional freezing to produce a high‐tensile, anti‐swollen PVA/MXene hydrogel with a layered structure. The hydrogel also retained its sensing and performance capabilities after prolonged water immersion, making it suitable for monitoring in aquatic environments [70]. In a separate study, Huang et al. enhanced the multifunctionality of MXene/CNC composite films by incorporating D‐PANI to improve conductivity, electromagnetic shielding, and photothermal conversion via synergistic interactions [71].

2.1.3. Biocompatibility and Long‐Term Safety

Biocompatibility and safety are critical for the use of MXenes in personalized wearable healthcare monitoring and therapy, where materials must remain active and functionalized in a biological environment for extended periods [72]. Determining the biosafety profile of MXenes is a complex process that involves several factors, including the material's nature, surface chemistry, dosage, exposure time, and biological context. Although MXenes have outstanding physical and electrical properties suitable for healthcare applications, the safety of integrating MXenes into biological systems needs to be critically analyzed [73, 74].

The concepts of toxicity and biocompatibility are related but distinct in terms of biosafety. While the former denotes negative impacts a material can have on cells or tissues, the latter relates to the material's ability to perform diagnostic or therapeutic roles without eliciting adverse biological reactions [75]. The ultrathin nature of MXenes, along with their high surface area, reactivity, and terminations, makes them highly reactive toward biological structures such as cell membranes, proteins, and other biomolecules, leading to adverse biological effects such as oxidative stress or inflammation, especially when exposed to high doses for prolonged periods [75, 76].

Another challenging issue that may hinder long‐term safety is the dynamic changes of MXenes under physiological conditions. Oxidation reactions, ion exchange, partial breakdown of material, and changes in surface chemistry due to long‐term exposure can all result in modifications to biological interactions during long‐term monitoring and therapy delivery [77]. To address these problems, much attention has been paid to developing biocompatible MXenes through surface functionalization and stabilization procedures. In addition, a promising line of research on the design of bioresorbable and degradable MXenes has gained popularity [78]. It is also important to conduct thorough in vivo and in vitro studies to assess immunological and toxicological effects and to determine safe use schemes for MXene‐based materials [79].

Recent experiments have indicated the promising biocompatibility of several MXene‐based materials. Like Rafieerad, et al., reported a Ta₄C₃T_x MXene‐tantalum oxide (TTO) hybrid that exhibited several desirable properties: it was fluorine‐free and highly biocompatible with various human cells. It possessed enhanced electrochemical performance [80]. Wang et al. fabricated MXene/chitosan films into flexible bimodal e‐skins. These devices exhibited low cytotoxicity and stable pressure and humidity sensing, making them suitable for monitoring physiological signals [81].

Jia et al. discovered that the properties of an MXene‐based film could be tuned by controlling the surface oxygen groups and the interlayer spacing of the composite. This tuning resulted in a material capable of reversible actuation and humidity biosensing, with a high degree of biocompatibility required for respiratory monitoring and actuator applications [82]. Furthermore, Diedkova et al. conducted a systematic study on the influence of different synthesis pathways on the biological behavior of Ti₃C₂T_x, a titanium‐based alloy, and its carbonitride counterpart, Ti₃C₁.₅N₀.₅Tx. Their work demonstrated that Na⁺ intercalation and water‐assisted etching significantly reduced hydroxylation and fluorine termination, thereby enhancing biocompatibility and decreasing inflammatory responses in human keratinocytes. Diedkova et al. provided a thorough description of the synthesis of MXene and its biomedical analysis, as shown in Figure 4I. The left side of the figure illustrates the transformation of MAX phases (Ti₃AlC₂ and Ti₃AlC₁.₅N₀.₅) into MXenes (Ti₃C₂T_x and Ti₃C₁.₅N₀.₅T_x) via acidic etching (HF or HCl) followed by Na⁺ or Li⁺ intercalation, which alters surface chemistry to enhance biocompatibility. The right side of the figure presents biological assessments, including cellular interactions, mechanisms of toxicity, and in vivo tolerance, supported by experimental data such as cell viability assays, expression of inflammatory markers, and tissue responses in animal models [83].

FIGURE 4.

Biocompatibility and Scalability of MXene (I) Synthesis and Biomedical Evaluation of MXenes: The left panel illustrates the transformation of MAX phases (Ti₃AlC₂ and Ti₃AlC₁.₅N₀.₅) into MXenes (Ti₃C₂T_x and Ti₃C₁.₅N₀.₅T_x) via HF/HCl etching and Na⁺/Li⁺ intercalation. The right panel presents biological assessments, including cellular viability, inflammatory response, and in vivo tolerance, highlighting the superior biocompatibility of Ti₃C₁.₅N₀.₅T_x and the influence of synthesis conditions on biosafety. Reproduced under license under CC‐BY 4.0 [83]. Copyright 2025, American Chemical Society. (II) presents the scalable preparation and characterisation of high‐yield monolayer MXene (H‐MXene) via high‐temperature sonication. (a) Schematic of the exfoliation process showing the dissociation of hydrogen‐bond cage confinement in multilayer MXene. (b–d) Photographs of MXene dispersions and films, highlighting color changes upon dilution and excellent flexibility of H‐MXene and I‐MXene. (e,f) TEM images and SAED patterns confirm clean morphology and consistent crystal structure. (g,h) AFM images with height profiles show monolayer thickness (∼1.3 nm). (i) XRD spectra verify complete etching and similar interlayer spacing (∼0.16 nm) in both H‐MXene and I‐MXene films. Reproduced with permission [84]. Copyright 2024, Wiley‐VCH GmbH.

2.1.4. Scalability and Manufacturing

The scientific community is highly attracted to MXene‐based devices for personal health monitoring and therapy, but their mass production remains a significant challenge. The current techniques employed for MXene fabrication, including vacuum‐assisted filtration, spraying, and layer‐by‐layer deposition, are time‐consuming and complex processes. In addition, the process is difficult to scale up, and there is less control over the film's uniformity, thickness, and consistency in these devices [85, 86]. The scalability issues are further complicated by MXenes' susceptibility to oxidation and other environmental conditions during production, which can affect the material's quality [87]. The ability to create a stable MXene ink that prevents flake restacking and provides adequate bonding to various substrate materials presents another hurdle that must be addressed during manufacturing [88]. The presence of different flake sizes, surface terminations, and dispersions can cause inconsistencies in material performance across larger batches of the produced product [89].

However, to overcome such challenges, manufacturing processes need to be developed that are both scalable and cost‐efficient. Various print‐based technologies, such as inkjet printing, screen printing, roll‐to‐roll coating, and additive manufacturing, may offer solutions to the problem at hand. These methods ensure the creation of an accurate pattern on a flexible/stretchable substrate, making them applicable to wearable technologies focused on personalized healthcare and therapy [90, 91].

In the fabrication context, Kim et al. introduced a scalable microfabrication‐based protocol that pairs photolithography with solution‐based processing to fabricate interdigitated micro‐architected microsupercapacitor (MSC) systems with pristine and nanoporous MXene electrodes. These flexible MSCs, fabricated on an 8‐inch wafer with a density of up to 107 chips, achieved a record volumetric capacitance of 1,727 F cm^{− 3} [92]. In another study, Wan et al. improved the performance of MXene films by using sequential hydrogen‐ and covalent‐bonding reagents to eliminate pores and fill the structure. The resulting films have high tensile strength, toughness, conductivity, and electromagnetic interference shielding, and can be scaled to incorporate other two‐dimensional materials as high‐performance composites [93].

A wet‐etching method for micropatterning Ti₃C₂Tz MXene was reported by Favelukis, et al., achieving a resolution of approximately 200 nm while maintaining structural and electrical integrity. These patterned film versions have been integrated into practical applications, including metal‐semiconductor metal (MSM) photodetectors, providing a clean, inexpensive, and scalable solution for future MXene microelectronics [94]. Jiang et al. proposed a blade‐coating approach to produce metal‐organic‐framework (MOF)‐MXene (TMox MXene, MOF/LMX) films that are highly stretchable and conductive, featuring Ti₃C₂Tx on stretched elastomers. The mechanical strength (≈ 97MPa), electrical conductivity (3244 S cm^{− 1}), and energy storage (1238 F g^{− 1}) of the text were increased by inserting the ultrathin sheets of MOF between the layers of MXene, and the material can be stable to bending and stretching as in wearable electronics [95].

To address a critical bottleneck in MXene manufacturing, Shi et al. aimed to eliminate the exfoliation of multilayer Ti₃C₂Tx into monolayer nanosheets. They introduced a high‐temperature bath ultrasonication technique to produce such sheets. This method is carried out at about 70°C, thereby weakening the hydrogen‐bond cages and allowing ultrasonic cavitation to break the layers effectively. As shown in Figure 4II (95%), monolayer MXene (H ‐MXene) is obtained after minutes of the process, as shown in Figure 4IIa. At full concentration, the dispersion appears deep black, and upon dilution, it forms light‐green, flexible, foldable films (Figure 4II‐b–d). The transmission electron microscopy and atomic force microscopy confirm smoothness of the surface and monolayer thickness (1.3 nm), whereas X‐ray diffraction proves total exfoliation and sustained interlayer distance (0.1 6nm) (Figure 4II‐e–i). It enables the fabrication of high‐concentration inks for scalable printing and device integration and has demonstrated infrared stealth and Joule‐heating performance [84].

Scalable manufacturing is an important aspect that will facilitate the commercialization of MXene‐based materials. Recent advances in MXene manufacturing, such as microfabrication, blade coating, wet etching, and efficient exfoliation, have significantly improved the mechanical, electrical, and structural properties of MXene‐based devices [96, 97]. These advancements help overcome manufacturing limitations and support the integration of MXenes into flexible, wearable, and multifunctional electronic systems. Ongoing innovation in large‐scale processing and device design will be vital for realizing the full capabilities of MXenes in future energy solutions, sensing technologies, and biomedical devices [87, 98].

3. Piezoelectric and Triboelectric Mechanisms

The piezoelectric effect is a phenomenon in non‐centrosymmetric crystals in which mechanical stress induces electric polarization, first discovered by Pierre and Jacques Curie in 1880 [99]. Piezoelectric nanogenerators (PENGs) utilize this effect to convert mechanical energy into electrical power. PENGs have been integrated into various platforms, further enabling the development of self‐sustaining, flexible wearable electronics [100].

Materials utilized in PENGs include high‐performance piezoceramics, flexible piezopolymers, and biodegradable biomaterials such as cellulose and collagen for biomedical applications [101]. Piezoelectric layers of PENGs are usually sandwiched between electrodes. Upon deformation, these materials develop surface charges due to domain realignment, thereby creating a potential difference arising from the asymmetry of the charge distribution [102], as detailed in Figure 5I. Figure 5I‐a, in the unstrained state, aligned domains do not generate net polarization; Figure 5I‐b, upon compression, the charge centers shift, leading to the formation of dipoles and the generation of voltage; Figure 5I‐c, at the maximum compressive state, polarization reaches its maximum value while electrode spacing is at its minimum; and Figure 5I‐d, upon release, electrons backflow, thus generating a reverse current [103]. PENG generally operates in d₃₁ and d₃₃ modes, while d₁₅ is relevant under shear stress [104]. From a materials perspective, ceramics offer high piezoelectric output but limited flexibility, whereas polymers provide mechanical resilience at lower electrical performance. Composite materials comprising both elements have thus been found to be promising, offering a balance of properties that makes them the most attractive for self‐powered wearable sensors and energy harvesting [105].

FIGURE 5.

Working Mechanism of Piezoelectric and Triboelectric Nanogenerators. (I) Schematic illustration of the working mechanism of film‐based piezoelectric nanogenerators (PENGs): (a) Dipoles are uniformly aligned in a regular direction after the poling process; (b) application of compressive force induces a piezo potential due to displacement of charge centers; (c) maximum polarization density is achieved when the electrodes are closest, enhancing charge interaction; (d) upon release of the force, electrons flow back to restore equilibrium, generating a reversed current. Reproduced with permission [103]. Copyright 2021, American Chemical Society. (II) Working principle of the TENG in contact‐separation mode. Reproduced under CC BY 4.0 [106]. Copyright 2020, The Hong Kong Polytechnic University and John Wiley & Sons Australia, Ltd. (III). Illustrates the two fundamental structural configurations of triboelectric nanogenerators (TENGs), double‐electrode and single‐electrode, each supporting three distinct working modes. In the double‐electrode configuration, (a) the vertical contact‐separation mode involves two dielectrics that generate surface charges upon contact and induce a potential difference upon separation; (b) the in‐plane sliding mode relies on lateral motion between surfaces, where frictional contact modulates the effective contact area and generates alternating current; and (c) the freestanding mode utilizes a moving triboelectric layer that interacts with surrounding materials, creating an asymmetric electric field without direct contact, thereby reducing wear. In the single‐electrode configuration, (d–f) represent the same three modes, but with only one active electrode and the other virtually grounded. This setup offers greater mechanical freedom, such as harvesting energy from walking or driving, although it may yield less stable electrical output due to the absence of a reference electrode. Reproduced with permission [107]. Copyright 2021, American Chemical Society.

The triboelectric effect has been known for a very long time; however, it was regarded as a detrimental phenomenon because it could result in an electrostatic discharge, thereby causing damage to electronic devices. In 2012, Wang et al. were the first to harness the triboelectric effect positively by developing the triboelectric nanogenerator (TENG), which generates energy from mechanical sources [12]. TENGs convert mechanical energy into electrical power via triboelectrification and electrostatic induction, and their performance depends on the operating mode and electrode configuration [108].

The TENG working principle can be described by utilizing a contact‐separation type TENG (Figure 5II). At the initial state, no electrical charge is accumulated at the electrodes. After contact between the two materials, oppositely charged areas form at their surfaces due to contact electrification. While the materials separate, a potential difference builds up across the electrodes, allowing electrons to pass from the bottom electrode to the top electrode through an external circuit. The electrical balance is reached when the materials reach their maximum separation distance, and the electrons cease to flow. If the separation is followed by pressing the materials together, a decrease in the voltage difference results in electron transfer back to the bottom electrode through the external circuit. Such contact‐separation operations continuously produce alternating electrical outputs as shown in the upper‐right part of Figure 5II [106].

TENGs can operate in three main working modes: contact‐separation (Figure 5III‐a), sliding (Figure 5III‐b), and freestanding (Figure 5III‐c). They can be implemented in both double‐electrode and single‐electrode setups. The single‐electrode configuration (Figure 5III‐d–f) offers greater motion flexibility but less stable output [107]. Triboelectrification at solid‐solid interfaces has been widely investigated, whereas few studies have examined non‐solid interfaces, even though this can effectively reduce wear. The mechanism of exact charge transfer, especially in nonionic insulators, remains controversial, and no universal model has yet been established. Beyond conventional polymers and metals, researchers have made efforts to expand the range of triboelectric materials by utilizing inorganic nonmetals, 2D materials, MOFs, COFs, ferroelectric compounds, and natural biopolymers. These materials offer tunable surface chemistry, high dielectric constants, and associated multifunctionality that can significantly improve the performance of TENGs. For example, 2D materials with atomic thickness, such as graphene, MXenes, and TMDs, have attracted considerable interest owing to their conductivity and surface adaptability. Expanding the material library is crucial for designing efficient, sustainable, and economically viable triboelectric nanogenerators [109, 110].

3.1. MXene‐Based Piezoelectric Nanogenerators (PENGs) for Energy Harvesting

Piezoelectric Nanogenerators (PENGs) are a type of energy harvester that operates on the principle of piezoelectricity, the ability of certain materials to transform mechanical strain into electrical energy. They are very efficient in energy collection and in driving autonomous biomechanical systems [65]. The introduction of MXene 2D materials into PENGs has significantly enhanced their functionality, owing to MXenes' high electrical conductivity, surface modification capabilities, and mechanical flexibility [33].

In recent studies, various MXene‐based designs have been explored to boost the piezoelectric efficiency and device integration [111]. For example, Tan et al. have demonstrated the piezoelectric characteristics of monolayer Ti₃C₂T_x MXene, where surface functional groups break the inversion symmetry of the lattice. A tensile strain of 1.08% applied to the material in the armchair direction generated a 0.3 nA current, providing a power density of 6.5 mW/m² and a conversion efficiency of 11.15%, surpassing that of other two‐dimensional materials. This performance was attributed to interactions between multi‐atomic structures and surface terminations, as determined by theoretical analysis [112]. Similarly, Cao et al. presented a composite PENG of Li ‐doped ZnO nanowires produced by hydrothermal treatment on Ti₃C₂ MXene. The MXene substrate also increased permittivity and served as a local ground, enabling efficient polarization of the ferroelectric nanowires and preventing particle aggregation. This hybrid structure achieved a twofold higher power density (∼9 µW/cm²) than composites without the MXene [113].

W. Guo et al. designed a miniature, self‐powered fire sensor (MPSFS) by combining near‐field electrospinning (NFES) technology using MXene/polyvinylpyrrolidone (PVP) paper and a piezoelectric nanogenerator (PENG). The system uses PVDF‐TrFE nanofibers, flexible printed circuit boards (FPCBs), and PDMS‐encased Ti₃C₂T_x MXene/PVP films with triply periodic minimal surface (TPMS) spacers to increase mechanical durability and energy‐output efficiency. The strong covalent bonding between MXene and PVP gives the material high flame resistance, and thermal oxidation converts the MXene film into a fish‐scale C/N‐TiO₂ structure, enabling fast detection (∼3.0 s) and stable cyclic alarm functionality. Additionally, W. Guo, et al., illustrates the device architecture in Figure 6I: panel (a) shows the schematic of the MPSFS; panel (b) displays the actual device (40 × 20 × 10 mm³), suitable for installation on furniture or inside drawers; panel (c,d) details the TPMS spacer, which can be fabricated using additive manufacturing with a porous design to reduce surface tension and distribute compressive force evenly; and panel (e) presents an SEM image of uniformly aligned nanofibers on the FPCB surface. This versatile platform demonstrates significant potential for smart fire‐safety applications in both wearable and embedded electronics [114].

FIGURE 6.

MXene‐based PENGs (I) Structural and fabrication overview of the MXene/PVP‐based self‐powered fire sensor (MPSFS). (a) Schematic of the MPSFS architecture, integrating NFES‐fabricated PVDF‐TrFE nanofibers with flexible printed circuit boards (FPCBs) and encapsulated in PDMS. (b) Photograph of the compact MPSFS device (40 × 20 × 10 mm³), suitable for installation on furniture or inside drawers. (c) Image of the flame‐retardant MXene/PVP film. (d) Additively manufactured TPMS spacer featuring central hole structures designed to minimize surface tension and distribute compressive stress. (e) SEM image showing aligned nanofibers on the FPCB surface. Reproduced with permission [114]. Copyright 2024, Elsevier B.V. (II) Schematic illustration of the synthesis process for CM@ZnO composite film. (a) Etching and exfoliation of MXene using LiF/HCl, followed by ultrasonic dispersion to obtain lamellar MXene. (b) Preparation of cellulose nanofibrils (CNF) via the TEMPO oxidation method. (c) Atomic structure representation of MXene, highlighting its layered morphology. (d) Overview of the hydrothermal growth process used to fabricate the CM@ZnO composite film by integrating MXene, CNF, and ZnO particles. Reproduced with permission [115]. Copyright 2024, Wiley‐VCH GmbH.

Zong et al. have designed a versatile piezoelectric nanogenerator (PENG) based on a PDMS‐infiltrated composite aerogel of cellulose nanofibrils and Ti₃C₂T_x MXene, intended to harvest energy from low‐frequency human motion. MXene nanosheets enhanced the structural homogeneity of the cellulose matrix and induced local polarization locking, thereby enhancing the piezoelectric response without electrical poling [116].

To address the problem of MXenes' self‐assembling and poor PVDF compatibility, Yin et al. demonstrated a significant enhancement in the piezoelectric properties of PVDF through reversible addition‐fragmentation chain‐transfer (RAFT) polymerization and click chemistry by grafting polyionic liquids onto MXene surfaces. After adding Fe₃O₄ nanoparticles to achieve magnetic orientation, a synergistic solution‐melt procedure was used to create a piezoelectric coefficient 15 times higher at 45 pC/N‐5 and an output current of 0.2 mA under a 120 N load [117].

Zu et al. utilized density functional theory (DFT) predictions to investigate the use of MXene to induce the α‐to‐β phase transition in PVDF, demonstrating increased dipole moments and interfacial adhesion arising from strong electrostatic and van der Waals forces [118]. Ding et al. produced pressure‐sensitive, breathable, PVDF/CNC‐based films, coated with MXene, exhibiting high mechanical strength (14.77/MPa), high sensitivity (52–225 kPa^{− 1}) and stability (more than 5000 cycles). These films were suitable for applications as wearable sensors, electronic skin, and for spatial pressure mapping [119]. Xu et al. developed a hybrid piezoelectric ‐triboelectric generator (PE ‐TENG) based on the use of the P(VDF‐TrFE) and polystyrene microspheres, which can work in two modes to obtain an open circuit voltage of 956 V and a short circuit current of 8.75 µA, which is sufficient to power electronic devices on the self [120].

Zhang et al. provided a 3D‐printing plan with solvent exchange to produce bamboo‐structured PVDF/MXene piezoelectric energy harvesters (PEHs). This structure increased interactions between the stress‐strain and produced a high 92.6% 8‐phase piezoelectric content, yielding 47 V of piezoelectric output and a sensitivity of 0.727 V/kPa. The versatile 3D PEHs demonstrated significant potential for motion‐tracking and intelligent‐sensing applications [121]. Zhu et al. prepared a cellulose‐based piezoelectric composite film (CM@ZnO) with a brick‐rebar‐mortar structure by combining cellulose nanofibrils (CNF), MXene, and ZnO. ZnO acts as a reinforcing bridge, thereby increasing both mechanical strength and piezoelectric performance. Moreover, Figure 6II illustrates the synthesis strategy of the CM@ZnO composite film. Panel (a) shows the preparation of lamellar MXene dispersion via ultrasonic treatment of LiF/HCl‐etched MXene powder. Panel (b) depicts the synthesis of ZnO seeds on TEMPO‐oxidized CNF. Panel (c) presents the spatial structure of MXene, while panel (d) outlines the final hydrothermal growth process used to fabricate the CM@ZnO composite film. This hierarchical approach enables efficient integration of components and enhances the material's piezoelectric performance [115].

In response to the growing demand for self‐powered devices, Kou et al. developed a flexible piezoelectric nanogenerator (PENG) by incorporating a hybrid nanofiller of nitrogen‐, sulfur‐, and phosphorus‐co‐doped graphene (NSPG) combined with Ti₃CNT_x MXene. The synergistic coupling of these components promoted interfacial adhesion and nucleated the electroactive β‐phase within the polymer skeleton. Using a greener electrochemical exfoliation process, a short‐circuit current of 1.48 µA, an open‐circuit voltage of 14.6 V, and a power density of 2.2 µW/cm² were realized, a fivefold improvement over pure PVDF, enabling effective harvesting of biomechanical energy to power small‐scale electronics [122].

To further improve the performance of wearable PENGs, Jin et al. proposed a confined‐orientation structure of PVDF/MXene nanofibers to overcome the non‐uniformity in β‐phase distribution. By integrating MXene, the nanosheets served as effective nucleating agents for the β‐phase and enhanced the alignment of the polymer chains. This dual role facilitated the efficient transfer of mechanical stress and the conversion of electromechanical energy. Due to this architectural sophistication, a piezoelectric coefficient of 61.7 pC/N, a transient response time of 14ms, and a pressure sensitivity of 19.29 mV/kPa were achieved, without compromising material flexibility [123]. Further advancements in the MXene‐based PENG field have focused on the development of multifunctional sensors and devices [33]. Wang et al. combined atmospheric‐pressure chemical vapor deposition of monolayer MoSe₂ ‐based PENG with electrospun PVA/Ti₃C₂T_x MXene nanofibers; the monolayer MoSe₂ component generates a peak output of 35 mV and a power density of 42 mW/m² [124].

Chandrasekar et al. designed a multifunctional PENG that incorporated partially oxidized MXene (MOP) into PVDF fibrous mats; the MOP(5) ‐PENG, which contained 5 wt.% of oxidized MXene, produced an output of 14.4 V, 1.6 µA, and a power density of 1.5 µW/cm² with a tactile sensitivity of 3.7 V/kPa which can transmit a digital signal. Partially oxidized MXene increased β‐phase crystallinity and dielectric performances by forming TiO₂ in situ. Additionally, the composite was a piezo‐photocatalyst, with 98% degradation of Rhodamine B dye by synergistic piezoelectric and photocatalytic processes at TiO₂/MXene heterojunctions [125].

Suresh et al. described a high‐efficiency PENG using anisotropic PVDF‐TrFE/MXene aerogels, addressing the self‐poling issue in piezoelectric polymers. Through unidirectional freezing, MXene nanosheets and PVDF‐TrFE chains were oriented along the solvent's crystal growth path, thereby strengthening intermolecular interactions and promoting the formation of electroactive β‐phase crystals. This natural alignment not only enabled dipole orientation without external poling but also generated an open‐circuit voltage of approximately 40 V with 3 wt.% MXene, compared to 1.5 V for isotropic aerogels. The device also functioned as a tactile sensor, exhibiting a sensitivity of 9.6 V/N to low forces and 1.3 V/N to high forces, thereby providing a scalable method for producing self‐powered, flexible energy‐harvesting systems [126].

Han et al. fabricated a PVDF/MXene piezoelectric microdevice via microinjection molding, which exhibited a high β‐phase crystallinity of 59.9% and a self‐polarizing effect induced by shear‐induced crystal orientation and MXene stacking. The device output an open‐circuit voltage of 15.2 V and a short‐circuit current of 497.3 nA with no external poling. As illustrated in Figure 7I, the microdevices were mounted on the front and side gears of a water rower to monitor athletic performance. Voltage outputs varied with gear position and movement frequency (0.9 and 1.8 Hz), thus permitting personalized tracking of training intensity. The robust structure and reliable signal output make the proposed devices ideal for smart sports equipment and exercise monitoring [127].

FIGURE 7.

MXene‐based PENGs, (I) Photographs showing the structure and working process of a rowing machine equipped with PVDF/MXene microinjected piezoelectric sensors. The sensors are assembled on the front gear (FG) and side gear (SG) to monitor mechanical force during rowing. Voltage outputs vary between FG and SG due to differences in impact force, with FG producing slightly higher signals. The sensing performance is further evaluated under different movement frequencies (0.9 and 1.8 Hz) and across individuals (athlete A and athlete B), demonstrating the device's capability to detect personalized exercise intensity and motion patterns. Reproduced with permission [127]. Copyright 2021, American Chemical Society. (II)  Dielectric characterization of LCE‐M hybrid polymers across the 2–18 GHz microwave band. (a,b) Complex permittivity (ε′ and ε″) increases with MXene content, indicating enhanced dielectric response and polarization‐relaxation behavior. (c,d) Counter maps of attenuation constant (α) and loss tangent (tanδ_e) show frequency‐dependent enhancement. (e,f) Quantitative comparison of α and tanδ_e across samples, with LCE‐M3 showing significant improvement over pure LCE. (g) Separation of polarization loss (ε″_p) and conduction loss (ε″c), confirming relaxation loss as the dominant mechanism. (h) ε″c and fitted conductivity values increase linearly with MXene content. (i) Deconvolution of relaxation peaks in ε″_p for LCE‐M3 reveals four distinct processes. (j–m) Cole‐Cole plots confirm Debye‐type relaxation: (j) orientation polarization in pure LCE (peaks I and II); (k) interface polarization in LCE‐M3 (peaks I and IV); (l) redshifted peak II; and (m) space‐charge polarization at peak III. Reproduced under Creative Commons Attribution 4.0. [128]. Copyright 2025, Springer Nature.

Kumar et al. proposed a PENG composite comprising silicone rubber, MWCNTs, and MXene to enhance mechanical and electrical performance. Replacing a small fraction of MWCNTs with MXene has resulted in significant improvements in tensile modulus (up to 1.41 MPa) and elongation at break (up to 195%). MXene‐based composites also exhibited more stable electrical signals and superior output under cyclic strain, with a voltage of ∼470 mV and a power density of ∼0.17 nW/cm². The piezoelectric coefficient was ∼19 pC/N, confirming MXene's role in enhancing PENG efficiency for stretchable, self‐powered electronics in remote and military applications [129].

Wang et al. developed a sensitized polymeric microwave actuator by hybridizing a liquid‐crystal polymer with Ti₃C₂Tx MXene, thereby achieving enhanced electromagnetic (EM) responsiveness and actuation efficiency. The hybrid structure exhibited a 230% increase in dielectric loss factor and an 830% improvement in EM energy conversion efficiency, with a rapid actuation response time of ∼10 s. A self‐powered sensing prototype was also demonstrated, generating real‐time electrical feedback (∼3 mV) during actuation. Moreover, Figure 7II details the dielectric behavior and EM energy harvesting capacity of the LCE‐M hybrid across the 2–18 GHz microwave band. Panels (a, b) show increased real (ε′) and imaginary (ε″) permittivity with MXene content, indicating enhanced dielectric properties and polarization‐relaxation behavior. Panels (c, d) present rising loss tangent (tanδ_e) and attenuation constant (α), with LCE‐M3 showing 107% and 153% higher values than pure LCE, respectively (e, f). Panel (g) distinguishes relaxation loss (ε″_p) as the dominant contributor to dielectric loss over conduction loss (ε″c), while panel (h) shows conductivity increasing linearly with MXene content. Panels (i‐m) illustrate Cole‐Cole plots, confirming Debye‐type relaxation processes. Peak III is attributed to space‐charge polarization, and peak IV to interface polarization. These findings highlight MXene's role in tuning polarization‐relaxation mechanisms for efficient broadband EM energy conversion [128].

Moreover, the summarized studies on the recent MXene‐PENGs are listed in Table 1.

TABLE 1.

Summarized Investigations on MXene‐based PENGs.

MXene type	Composite	Fabrication	Electrical output	Application	Refs.
Ti3C2Tx	PVDF/AgNP/MXene nanofiber	Near‐field electrospinning	high d33	Self‐powered wearable sensors	[130]
Ti3C2Tx	PVDF‐TrFE/Ti3C2Tx (self‐poling)	Printable composites	d33 ≈ −52 pC·N− 1	Energy harvesting w/o high‐voltage poling	[131]
Ti3C2Tx	Solution‐processed PVDF/Ti3C2Tx	Casting/solution processing	Power density: 56.9 µW/cm3	Flexible NG/sensors	[132]
Ti3C2Tx	PVDF/PMMA‐Ti3C2Tx blend	Solution‐cast flexible films	Power density: 4.86 MW/cm3	Energy storage capacitors	[133]
Ti3C2Tx	PVDF/CsPbBr3/Ti3C2Tx composite fiber	Electrospinning + heterojunction engineering	160 V (self‐polarized), powers 150 LEDs	Wearable energy harvesting	[134]
Ti3C2Tx	PVDF‐TrFE/MXene nanofiber mats	Electrospun composite nanofibers	∼3.64 mW/m2 power density (20 N, 1 Hz)	Self‐powered linear pressure sensors,	[135]
Ti3C2Tx	Spatially confined MXene/PVDF nanofiber electronics	Confined electrospinning	3.97× higher voltage, 10.1× higher current vs pure PVDF	Piezo electronics + PENG	[136]
Ti3C2Tx	Ti3C2Tx‐coated electrospun PVDF‐TrFE nanofibers	Electrospinning + MXene coating	20× higher voltage vs pure PVDF‐TrFE	Wearable energy harvesting	[137]
TiVCrMoC3Tx	MXene‐PVA composite nanogenerator	HF‐free synthesis; PVA cross‐linking	∼0.5 V; ∼790 pA under 3.47 N	Flexible NG for wearables	[138]
Ti3C2Tx	BaTiO3/MXene/PVDF‐TrFE composite films	Electrospinning heterostructure	Output: 7.6 V; β‐phase (81.04%)	Wearable motion monitoring	[139]
Ti3C2Tx	PAN/BaTiO3/MXene nanofibrous membrane PENG	Electrospinning	power density 3.4 mW·m−2	Wearable energy harvesting	[140]
Ti3C2Tx	Flexible MXene/PVDF composite film PENG	Solution casting/film fabrication (lead‐free)	Piezoelectric performance (Voc = 7.98 V).	General wearable energy harvesting	[141]

3.2. MXene‐Based Triboelectric Nanogenerators (TENGs) for Energy Harvesting

Triboelectric nanogenerators (TENGs) are increasingly recognized as adaptable devices that convert mechanical energy, such as human motion, into electrical power through contact electrification and electrostatic induction [142]. Their flexibility makes them highly suitable for wearable electronics and human‐machine interface applications [143]. Recent advancements have demonstrated that incorporating MXenes, a class of 2D materials with tunable surface chemistry and excellent conductivity, can significantly enhance the performance of TENGs. MXenes function effectively as triboelectric layers or electrodes, improving charge transfer and mechanical robustness [25, 26].

Several researchers are actively exploring MXene‐based TENGs for energy harvesting. For example, Wang et al. reported a biodegradable TENG (NMTS‐TENG) using a composite of NH₂‐MXene, TiO₂, and sodium alginate. This design demonstrated high mechanical strength (175 MPa) and a high electrical output (357.6 V, 55.1 µA). The NMTS‐TENG harvested ocean wave energy to power electronic equipment and provide self‐powered corrosion protection [144]. M. Wang et al. focused on harvesting droplet energy by modifying PDMS with MXene and ZIF‐8. The performance of the modified material, PZM‐TENG, was significantly improved, with the voltage increasing by 46 times and the current by 26 times compared with unmodified PDMS. This gain in power helped to power small devices and even cathodic protection [145].

L. Zhou et al. developed a versatile TENG using TEMPO‐oxidized cellulose nanofibers (TOCNF) in combination with MXene. The composite served as both the triboelectric layer and the electrode, delivering a high output (210 V, 0.84 µA) and thus acting as a highly efficient self‐powered sensor for measuring motion and handwriting [146]. X. Zhou et al. prepared a biodegradable MXene/GEL/SL composite film, which possesses a high electromagnetic interference (EMI) shielding and triboelectric behavior. The incorporation of Fe^{3 +} ions induced cross‐linking, which contributed to the film's high shielding performance (432 dB/mm) and stable electrical output (230 V, 28 µA, 2.9 W/m²), enabling its use in wearable health sensors [147].

Y. He et al. developed a single‐electrode triboelectric nanogenerator (CM ‐TENG), comprising a composite film consisting of chitin nanocrystals (ChNCs) mixed with MXene. In this composite, ChNCs acted as interfacial adhesives to enhance mechanical strength and conductivity. They also neutralized the MXene's surface charges, thereby promoting electron mobility during electrostatic induction. This resulted in a power density of 99.5 mW/m², enabling its use as a self‐powered strain and tactile sensor in wearable electronics. Moreover, Figure 8I‐a shows the working principle of the CM‐TENG, which operates via triboelectric activation and electrostatic induction. Glass was used as the friction layer, and when contact‐separation cycles were performed with PDMS, charge transfer and induction occur in four states, producing an alternating current. Figure 8I‐b illustrates the stratified design of the ChNCs/MXene composite film, where ChNCs were dispersed between the MXene nanosheets, which facilitates charge induction, storage, and rapid charge transport [148].

FIGURE 8.

MXene‐based TENGs. (I‐a) Functional principle of the CM‐TENG in single‐electrode configuration, depicting the triboelectric activation and electrostatic induction processes during the contact and separation of glass and PDMS. (b) Diagram of charge storage and transfer within the stratified ChNCs/MXene composite film, where interspersed ChNCs improve electrical conductivity, enabling efficient induction, retention, and discharge of charges during mechanical distortion. Reproduced with permission [148]. Copyright 2024, Elsevier B.V.  (II) Applications of FW‐TENG: (a) illumination of LEDs through hand and foot movements; (b,c) operation of a digital thermo‐hygrometer and stopwatch powered by hand tapping, with voltage profiles for 33 and 10 µF capacitors; (d) LED illumination using energy from rainfall, with FW‐TENG integrated into a raincoat and umbrella; (e) energy capture from wind using airflow from a fan; (f) intelligent carpet sensor detecting foot activity with a buzzer alert; (g) motion sensor for sleep monitoring, detecting movements beneath a bed sheet. Reproduced with permission [149]. Copyright 2020, Wiley‐VCH GmbH.

Guo et al. reported a high‐output TENG based on a PVDF‐TrFE composite doped with MXene and BTO: La. The co‐doping approach enhanced the dielectric properties and reduced energy loss, yielding a high output voltage of 150 V and a power density of 3.12 W/m² [150]. Md Salauddin et al. developed FW‐TENG, a water‐resistant, textile‐integrated triboelectric nanogenerator, using an innovative MXene/Ecoflex nanocomposite that exhibits a highly negative triboelectric nature and high mechanical strength. The maximum power output of the FW‐TENG under optimum conditions with a 4.5 MΩ load resistance, 4.5 Hz frequency, and 8 N force was 3.69 mW, with a power density of 9.24 W·m^{− 2}. The versatility of the FW‐TENG was demonstrated through several applications, as shown in Figure 8II. As shown in Panel (a), energy generation through the action of the hands and feet was observed, with the FW‐TENG attached to a wrist or on the floor, turning on an LED on some 360 and 240 lights, respectively. Panels (b) and (c) show that it has the potential to store energy: a 33 µF capacitor, charged to 1.75 V in 28 s, drove a digital thermo‐hygrometer 8 s, and a 10 µF capacitor, charged to 1.7 V in 14 s, drove an electronic stopwatch 6 s. Panel (d) illustrates energy harvesting from rainfall, where water droplets strike FW‐TENGs integrated into a raincoat and umbrella, powering approximately 120 LEDs. Harvesting wind energy is depicted in panel (e), where a fan moves the air that drives approximately 240 LEDs, demonstrating that the device can harness wind energy from various directions. The smart carpet sensor application, equipped with a buzzer alarm triggered by foot motion on panel (f), could be used to detect entry. A sleep monitoring system is presented in panel (g), and the FW‐TENG was installed beneath a bedsheet to track any side‐to‐side movement of a patient during sleep, triggering a patient safety buzzer alarm. These demonstrations highlight the potential of the FW‐TENG for self‐powered sensing, environmental energy management, and integration into next‐generation smart fabrics and wearable electronics [149].

Chen et al. developed a leaf‐inspired conductive hydrogel (PCM) made of TOCNF, tannic acid, and MXene. This hydrogel was highly stretchable (>800%), fatigue‐resistant, and adhesive, making it a good TENG electrode. The PCM‐TENG demonstrated an output of 106 V and approximately 2 µA [151]. Pratap et al. developed a sustainably fabricated, printed TENG based on a PVBVA‐MXene composite. The TENG was developed using extrusion printing on aluminum and silver ink electrodes, yielding a power density of 760 mW/m² and significant improvements in voltage (129%) and current (250%). The fully printed TENG demonstrated real‐time motion sensing, with applications in healthcare, robotics, and wearable electronics [152]. Shuvo et al. demonstrated that adding 10% MXene to PVDF enhances the dielectric properties and power output of both single‐electrode (SE‐TENG) and contact‐separation (CS‐TENG) devices. SE ‐TENG generated 405 V, 221 nC, and 1.3 mW, and CS ‐TENG generated 3365 V, 341 nC, and 13.07 mW, indicating that MXene/PVDF composites could be used to develop advanced wearable technology [153]. The MXene‐silicone nanocomposite TENG developed by Madathil et al. exhibits a power density of 14.9 W/m², which was three times greater than that of silicone‐based TENGs. This device energised compact electronic devices and was incorporated into a self‐sustaining touch‐sensing system with wireless notification capabilities, indicating potential for intelligent interfaces and security applications [154].

S. Fang et al. developed a highly elastic, water‐repellent cellulose nanofiber (CNF)/MXene composite aerogel for use in triboelectric nanogenerators (TENGs), addressing key limitations of biobased materials, including poor mechanical strength and hydrophilicity. By employing fluorosilane cross‐linking and oriented freeze‐drying, the DF‐CNF/MXene aerogel exhibited remarkable compressibility (up to 80% strain), rapid recovery (95.33% rebound height), and water‐repellent properties (water contact angle of 137.65°). Consequently, the aerogel provided an output voltage of 100 V and a short‐circuit charge density of about 900 nC·cm^{− 3}, with stability over 1000 cycles [155]. The PMMG‐TENG (PDMS‐MXene/gelatin triboelectric nanogenerator) introduced by Wang et al. features microstructures inspired by peony petals. The highest % increase in electrical output was 228.17%, with a doping concentration of 0.03 wt.% MXene, and peony‐petal molds with 417.39 V, 12.01 µA, and 170 µW/cm². The device remained functional beyond 10 000 cycles and was also quickly biodegradable, offering a sustainable, scalable model of wearable energy harvesting [156].

J. Fan et al. reported a flexible TENG by loading Ti₃C₂ MXene and cellulose nanofibers onto a cotton textile to create a conductive electrode layer. The MXene imparted electrical conductivity and triboelectric electronegativity, whereas the cotton substrate provided mechanical strength and elasticity. The TENG, featuring a silicone‐rubber friction layer in a single‐electrode configuration, produced an open‐circuit voltage of up to 400 V during palm press‐and‐release cycles, the harvested energy used to charge capacitors and power 32 green LEDs. The device also functioned as a self‐powered sensor, demonstrating high reproducibility and linearity when determining the mass of steel specimens ranging from 2 to 200 g. It maintained its performance at strains below 100% and responded to bending and folding in different directions, making it suitable for tracking physiological movements in wearable applications [157].

Jia et al. prepared multifunctional electro‐/photo‐thermal hybrid films (EHFs) by sequentially spraying silver microparticles (AgMPs) and MXene dispersion onto a waterborne polyurethane (WPU) film, followed by hot‐pressing. The resulting EHFs demonstrated high electrical conductivity (1.17 × 10⁴ S·m^{− 1}), strong Joule heating (121.3°C at 2 V), and a strong photo‐thermal response (66.2°C in 70 s under 100 mW·cm^{− 2}). The EHFs delivered 38.9 nC in short circuit, 114.7 V in open circuit, and 0.82 µA in short circuit when connected to single‐electrode triboelectric nanogenerators (STENGs). This further increased the output using two layers of triboelectrification. In Figure 9I‐a, Jia et al. presented the STENG assembly, in which a copper wire was placed before MXene deposition. The working principle is illustrated in Figure 9I‐b, where the negative and positive triboelectric components are silicone rubber and WPU, respectively, serving as contacting and separating surfaces. The alternating flow of electrons induced by cyclic contact and separation between the surfaces produces electrical signals, which are supported by the COMSOL results. The linear motor‐based tests (40 × 40 mm² contact area, 10 N force, 5 Hz frequency) demonstrated that the higher the AgMPs loading, the better the output, i.e., lower surface resistance and increased contact area (Figure 9I‐c). In addition, charge neutralization was reduced, and the voltage of charge (V_OC) curved upward with frequency due to the increased charge accumulation (Figure 9I‐d). Jia et al. introduce a scalable approach to flexible EHFs with enhanced energy‐conversion efficiency, making them promising for wearable electronics and hybrid energy‐harvesting systems [158].

FIGURE 9.

(I) MXene‐based TENGs, (a) Structure of the EHFs‐based STENG with embedded copper wire, (b) Working mechanism showing charge generation and transfer during contact‐separation cycles, (c) Electrical output performance: V _OC = 114.7 V, I _SC = 0.82 µA, and QSC = 38.9 nC under periodic tapping. Reproduced under Creative Commons Attribution 4.0, [158]. Copyright 2021, Springer Nature (II) Monitoring vibrations of a nano precision motion platform using FC‐TENG: (a) schematic of vibration detection setup; (b) FC‐TENG output at varying PZT driving frequencies (constant amplitude of 100 V); (c) VOC response at different PZT driving voltages (constant frequency of 1 Hz); (d) linear fit of VOC versus PZT voltage amplitude; (e,f) VOC changes with 0.05 and 0.1 V increases in PZT voltage, demonstrating high resolution and sensitivity. Reproduced with permission [159]. Copyright 2025, Elsevier B.V.

A pressure‐sensing triboelectric nanogenerator (FC‐TENG) was developed by Yuan et al. using a flexible styrene‐ethylene‐butyl‐styrene (SEBS) membrane impregnated with both barium titanate (BTO) and MXene nanoparticles. This ferroelectric coupling significantly increased the dielectric constant while reducing dielectric loss, leading to a linear sensitivity of 0.4 V·kPa^{− 1} (5–100 kPa) and 0.2 V·kPa^{− 1} (100–250 kPa) and a maximum power output density of 1.23 W·m^{− 2}. FC‐TENG effectively detects pressure signals with high accuracy in real time, making it suitable for intelligent human‐machine interaction and health‐monitoring applications. Additionally, Figure 9II shows the utility of the FC‐TENG for vibration detection on a nano‐motion platform. In panel (a), the FC‐TENG is attached to a motion platform of piezoelectric (PZT) type, and the vibrations create electrical signals by repeatedly touching and frictionally separating friction layers. Panel (b) demonstrates the outputs of voltage waveforms at a constant 100‐V driving voltage of the PZT in input frequencies with 0.5Hz to 5Hz frequency variation, with constant amplitude and varying frequency‐dependent waveforms. Output waveforms with varying PZT voltages (2.5–150 V) are shown in panel (c) at 1Hz, showing a linear voltage response. Linearity of panel (d) is ensured at the coefficient of determination (COD) of 0.99994 with a slope of 0.71 mV/V. The sensor resolution is shown in panels (e) and (f), where a 0.05 V voltage change is detected, and a significant difference of 0.02 V is observed with no change. These results support the FC‐TENG's high sensitivity, linearity, and resolution for detecting small vibrations in integrated nano‐motion sensors [159].

Moreover, a summary of the recently reported MXene‐based triboelectric nanogenerators is provided in Table 2.

TABLE 2.

Summarized investigations on MXene‐based TENGs

MXene type	Composites	Electrical performance	Applications	Refs.
Ti3C2Tx	Moisture‐adaptive cellulose/MXene aerogel (hybrid MEG‐TENG)	106 V; 400 µA cm− 2 (current density); 77 µW cm− 2 (power density)	All‐weather plant/wildlife sensors	[160]
Ti3C2Tx	Printed PVBVA‐MXene on Al/Ag‐ink electrodes	760 mW m− 2; +129% V oc, +250% I oc	Motion sensing	[161]
Ti3C2Tx	MXene/PVDF nanofiber (negative) + Ethyl cellulose/PA6 (positive)	290 mW/m2 peak power density at 100 MΩ	Self‐powered wearable sensors	[162]
Ti3C2Tx	Double‐side‐contact MXene/silicone w/ fabric‐micropatterning (DSC‐TENG)	55.47 W m− 2	Smart home, HMI	[163]
Ti3C2Tx	MXene/PTFE composite	397 V; 21 µA; 232 nC charge transfer	Wearable energy harvesting	[164]
Ti3C2Tx	MXene liquid electrode TENG	V oc up to ∼300 V	Soft robotics, HMI, wearables	[165]
Ti3C2Tx + graphene	Stretchable MXene/silicone + AgNW‐graphene‐foam electrode	73.6V, 7.75uA, Power 2.76 W m−2	Self‐powered sensing/harvesting	[166]
Ti3C2Tx	SF@MXene‐A aerogel (positive) + PDMS sponge (negative)	545 V (V oc), 16.13 µA (I sc) – 2‐3× higher than other aerogel TENGs	Wearable diagnostics, self‐powered breath sensors	[167]
Ti3C2Tx	NPCO/silicone (top layer) + MXene/silicone (intermediate layer)	10.4 W/m2 power density, 5.82 V/kPa sensitivity	Self‐powered biomotion sensors	[168]
Ti3C2Tx	PVDF‐TrFE/MXene electrospun mat (EN‐TENG)	4.02 W m− 2 (@4 MΩ)	Powering small devices	[169]
Ti3C2Tx	TMS/PET (negative) + NaCl/PVA (positive)	V oc: 390–500 V, I sc: ∼96 µA, Power density: 6.66 W/m2	self‐powered sensors	[170]

3.3. Environmental Challenges for MXene PENGs and TENGs

The recent discovery of two‐dimensional transition metal carbide, nitride, and carbonitride‐based MXenes is highly promising for use in piezoelectric nanogenerators (PENGs) and triboelectric nanogenerators (TENGs) due to their excellent electrical conductivity, large surface area, controllable surface chemistry, and mechanical flexibility [171]. The unique combination of properties of MXene‐based nanogenerators makes them highly suitable for IoT applications, including self‐powered sensing and wearable electronics. However, MXene‐based PENGs and TENGs have significant environmental drawbacks that compromise their stability and reliability [172].

The primary environmental challenges in MXene‐based PENG and TENG are oxidation and hygroscopicity, as MXene readily oxidizes in the presence of oxygen and moisture. This oxidation leads to the formation of metal oxides, such as titanium dioxide (TiO₂), resulting in low electrical conductivity and poor surface functionalization [35]. Considering the fundamental principles behind TENGs and PENGs, the energy conversion efficiency and device lifetime are significantly affected because they depend on a stable surface charge density and effective charge transfer [173].

Temperature fluctuations also pose a significant challenge because MXene‐based nanogenerators are primarily designed for wearable and outdoor devices that experience extreme temperature variations [174]. High temperatures accelerate oxidation reactions and cause MXene flakes to disintegrate, whereas low temperatures can make them less flexible and less able to transfer charges between layers [175]. Moreover, cyclic heating/cooling processes could result in the buildup of mechanical stresses at the interface between MXenes and the polymers used in composite PENG and TENG materials, leading to device malfunction due to delamination and microcracking [176].

Mechanical fatigue under cyclic loading conditions poses another challenge to MXenes' environmental resilience. PENGs and TENGs undergo cyclic mechanical deformation in the form of flexing, stretching, compression, or vibration [111]. Despite the inherent mechanical flexibility of MXenes, repeated mechanical strain in the presence of moisture or chemical reactions can lead to flake breakup, interfacial slippage, and disruption of conductive paths [24, 177]. In TENG devices, mechanical wear resulting from repeated surface separation and sliding alters the triboelectric characteristics of MXene films. In contrast, in PENGs, cyclic fatigue may affect the piezoelectric properties of MXene‐polymer blends [177].

Stability of the material and environmental reactivity are other factors that pose problems. The terminations of the MXenes (e.g., ─OH, ─O, ─F) are highly reactive and susceptible to reactions with environmental contaminants, which may be present in acidic form, or salt, as well as pollutants [178]. The presence of sweat, oils, and biological fluids in biomedical or wearable devices may induce chemical changes at the device surface, potentially influencing charge generation and transfer [179].

Various strategies to solve MXene environmental challenges include surface passivation, polymer encapsulation, antioxidant addition, and hybrid material engineering. The use of encapsulants such as elastomers, hydrogels, or barrier films will greatly improve their ability to withstand moisture and provide mechanical strength. Surface modifications, along with careful termination engineering, will contribute to chemical stability, whereas a combination material will help prevent fatigue and material wear [52, 180, 181].

Researchers are actively working to address these challenges. For example, Sun et al. proposed an MXene‐SHP composite (mSHP) that exhibits improved mechanical and dielectric properties, with a high piezoelectric output of 30 V and 4.2 µA and demonstrates water stability for touch‐sensitive applications in both air and aquatic environments [179].

Shaukat et al. present MOF‐5‐based TENGs and PENGs operating under extreme conditions, showing very high output (TENG: 484 V, 40 µA; PENG: 27 V, 2.9 µA) and the capability to power small electronic devices [182]. Li et al. developed an MXene‐reinforced hydrogel with outstanding mechanical properties, electrical conductivity, and environmental resilience. The hydrogel exhibited rapid self‐healing, strong adhesion to diverse substrates, and a wide operating temperature range (−20 to 80°C), making it suitable for skin‐like sensors in complex environments [183].

Wang et al. introduced a self‐powered NH₃ sensor based on a TENG‐driven MXene/CuO composite that exhibited high‐voltage output and effective gas sensing at room temperature, demonstrating promising potential for monitoring food freshness and wearables [184]. Zhang et al. designed a hybrid MEG‐TENG device featuring a biomimetic aerogel structure that adapts to a wide humidity range from 20% to 90%, enabling efficient energy harvesting from both moisture and triboelectrification. The device exhibits high power density and biodegradability, making it an ideal platform for sustainable applications such as plant sensors and wildlife tracking [160]. Song et al. proposed a 3D‐printed, heat‐resistant TENG sensor that operates up to 200 °C. Integrated with neural networks and virtual reality platforms, Song et al.’s sensor precisely captures human motion, opening a new pathway for safety monitoring in high‐temperature environments [185].

These works together illustrate that composite engineering, surface modification, and the integration of multiple functions offer promising strategies for designing MXene‐based nanogenerators with tailored performance to address various environmental challenges and real‐world application demands.

4. Applications

4.1. Wearable Health Monitoring

Nanogenerators‐based self‐powered wearable health monitoring is a growing field in the healthcare sector because they enable continuous, real‐time monitoring of physiological signals without external energy sources [186]. Nanogenerators capture biomechanical energy from daily physical activities, such as walking, breathing, joint movement, and skin flexing. At the same time, power sensors to measure vital signals, such as heart rate, breathing rate, blood pressure, and body movements [187].

MXene‐based piezoelectric and triboelectric nanogenerators have great potential for self‐powered wearable health monitors owing to their flexibility, low weight, high conductivity, and high skin compatibility. The adjustable surface chemistry enables enhanced signal transduction efficiency and increased sensitivity in the monitoring process [111, 188].

Recent advancements in piezoelectric and triboelectric wearable health technologies have sparked growing interest in self‐powered, sustainable systems for continuous biosignal monitoring [189]. In this respect, Yi et al. proposed a wearable, MXene‐based, self‐powered device fabricated via 3D printing on a stretchable SEBS substrate. The system utilizes biomechanical energy to provide real‐time monitoring of radial artery pulses, eliminating the need for external power sources and wireless communication via near‐field data and energy transmission. This innovation represents a significant step toward autonomous, personalized healthcare solutions [190].

Piezoelectric nanogenerators (PENGs) have been promising for self‐powered physiologic monitoring devices. However, many traditional piezoelectric polymers require energy‐intensive poling operations, limiting their scalability and stability [191]. To address these limitations, Li et al. proposed a self‐poling composite fabricated via extrusion‐based 3D printing, embedding MXene nanosheets in PVDF‐TrFE to align the dipole under shear stress. This led to the development of a nanogenerator with significant output performance and versatility, enabling sensitive detection of human movement and expression [192]. An et al. reported a multifunctional piezoelectric sensor using a mixture of MXene in waterborne polyurethane (WPU) to develop stable WPU‐MXene emulsions. The best results were obtained with a 0.7% MXene loading, a reaction time of 6 h, and an open‐circuit voltage of 5.79 V at a 20N load; the short‐circuit current was 463 nA. The composite film was fabricated into a multilayer nanogenerator with a PI‐electrode‐composite membrane‐electrode‐PI structure (Figure 10I), exhibiting ferroelectric, photothermal, flame‐retardant, and mechanically robust properties. This strategy offers a flexible platform for developing intelligent, multipurpose wearable sensors [193].

FIGURE 10.

Application of MXene‐based PENG for wearable physiological monitoring. (I) Schematic illustration of the fabrication process of the WPU‐MXene composite film, highlighting the stable emulsion formation and integration of MXene into the waterborne polyurethane matrix, and its application in a multilayer piezoelectric nanogenerator structure, demonstrating its multifunctional capabilities, including ferroelectricity, mechanical robustness, and sensor integration. Reproduced with permission [193]. Copyright 2025, Elsevier B.V. (II)  Illustration of a throat‐mounted communication system designed for medical rehabilitation: (a) schematic representation of the integrated system for speech‐based interaction and cough monitoring, particularly relevant during infectious disease outbreaks; (b) waveform data capturing vocal cord vibrations during speech and coughing from a human subject; and (c) schematic of the device setup enabling biomechanical energy harvesting and real‐time speech‐to‐text conversion, Reproduced with permission [194]. Copyright 2025, Elsevier Ltd. (III) Porous MXene/PVDF e‐skin arrays for texture sensing, including fingerprint pattern detection and surface texture recognition through scanning over embossed structures. Reproduced with permission [195]. Copyright 2021, Elsevier Ltd.

Waqar et al. developed a pliable, throat‐worn piezoelectric nanogenerator (FPENG), composed of MXene, BaTiO₃ and f‐f‐MWCNTs embedded into a PDMS‐based matrix, to solve communication problems in noisy and obstructed conditions, trapping the vocal‐cord oscillations rather than ambient sound, producing a peak output of about 1.2 V. FPENG facilitates easy communication among clinicians wearing protective equipment, as shown (Figure 10II‐a). Figure 10II‐b demonstrates its capability to differentiate between speech and coughs through waveform analysis, and Figure 10II‐c provides a schematic of its sensing and transcription system. Real‐time respiratory monitoring was also supported by the device, making it particularly well‐suited for health care and industrial applications [194].

Kim et al. developed 3D porous MXene/PVDF composite‐based high‐sensitivity, self‐powered piezoelectric e‐skins. The inclusion of MXene enhances the ferroelectricity of PVDF via hydrogen bonding and sensitivity, with porous MXene showing low‐ and high‐pressure sensitivities of 11.9 and 1.4 nA·kPa^{− 1}, respectively, which are superior to those of the planar design. The e‐skin exhibits a steady performance of 5000 cycles and is sensitive to both high‐frequency (e.g., acoustic, frictional) and low‐frequency (e.g., pulse) signals. A 1 × 8‐pixel e‐skin array, as depicted in Figure 10III, was used to sense fingerprint patterns and to produce a 3D‐printed MXene texture with specific line dimensions. The results highlight the wide range of applications of e‐skin across wearable electronics, prosthetics, robotics, and health monitoring [195].

Triboelectric nanogenerators (TENGs) have also emerged as a promising technology for converting mechanical energy into electrical energy due to their lightweight design, cost‐effectiveness, and high energy output. Their development has been rapid, driven by an ever‐growing need for sustainable, portable power sources and by ongoing innovation in nanomaterials [27].

Several Researchers are actively exploring MXene‐based TENGs for wearable health monitoring. For example, Ali Mirsepah et al. designed a self‐powered wearable photodetector by integrating a MoS_2‐based photodetector with a PDMS MXene triboelectric nanogenerator. The TENG produces an alternating current (AC) voltage, which was rectified to direct current (DC) using a diode and stored in a capacitor. The photodetector exhibited high sensitivity and millisecond‐scale response times, enabling heart rate measurement with a 660 nm LED and ultraviolet radiation detection with a 395 nm LED. Figure 11 depicts the fabrication process showing the mixing of PDMS with MXene and spin‐coating it onto the aluminum foil (Figure 11I‐a,b), and incorporating the LED, TENG and photodetector into a PDMS wristband (Figure 11I‐c), demonstrating the feasibility of creating a compliant and environmentally friendly wearable sensing platform [196]. Wang et al. reported the fabrication of a 3D microporous MXene/polyurethane (MXene/PU) composite gel fabricated using an iron foam template. The composite developed a strong network via hydrogen bonding, resulting in a piezoresistive sensor with high compressive strength, long‐term stability (20 days, 2000 cycles), and a sensitivity of 0.96144 kPa^{− 1}. Its versatility for wearable electronic applications was reinforced by its effectiveness in plantar health monitoring and its compatibility with TENG architectures [197].

FIGURE 11.

Application of MXene‐based TENG for wearable physiological monitoring. (I)Schematic representation of the fabrication and integration process(a) blending PDMS with MXene, (b) spin‐coating the resulting composite onto an aluminum substrate, and (c) integrating the LED, TENG, and photodetector into a PDMS wristband to develop a pliable, self‐sustaining wearable sensing platform. Reproduced with permission [196]. Copyright 2024, Elsevier B.V.  (II) Summary of DSC‐TENG applications: (a) diagram illustrating biomechanical energy capture for energizing wearable devices; (b) diagram depicting wireless smart home automation via DSC‐TENG; (c) LED illumination triggered by hand clapping, tapping, and finger contact; (d) smart home system managing fan and lighting operations; (e) intelligent table configuration for anti‐theft protection activated by skin contact; (f) showcase of energizing a pedometer, hygrometer, and stopwatch through capacitor charging, featuring voltage profiles and smartphone‐enabled real‐time visualization. (g) wearable keyboard for password verification displaying voltage signals for the A, S, E, and R keys; (h) human movement tracking system for IoT integration. Reproduced with permission [163]. Copyright 2021, Wiley‐VCH GmbH.

Salauddin et al. reported a scalable and versatile surface‐modification approach, fabric‐assisted micropatterning of MXene/silicone nanocomposites, that produces high‐efficiency double‐sided‐contact triboelectric nanogenerators (DSC‐TENGs) suitable for self‐sustaining wearable electronics. The technique allows the direct fabrication of microstructured surfaces without the use of surface‐active agents or specialized equipment. Using optimal fabric texture and MXene loading (3 mg cm^{− 2}), the DSC‐TENG demonstrated significant performance improvements, with output voltage and peak current density rising by factors of 9.8 and 20, respectively, and reaching a peak power density of 55.47 W m^{− 2} with an external load of 0.18 MΩ. The device also exhibited multiple functionality changeable across a variety of applications, as shown in Figure 11II: wireless powering smart‐home appliances with biomechanical energy‐harvesting of hand motions (Figure 11II‐a,b); electricity generation by hand clapping, tapping and finger‐touch (Figure 11II‐c); acting as a touch sensor in smart‐home control when integrated into a wristband (Figure 11II‐d); and as a security in a smart‐table system that produces alarms and LEDs in the event of unauthorized contact (Figure 11II‐e) It also supported low‐power peripherals like a pedometer, hygrometer and a stopwatch using capacitor charging by tapping hands (Figure 11II‐f). A flexible wearable keyboard (FWK) based on the DSC‐TENG was demonstrated for password authentication by generating distinct voltage signals from finger touches (Figure 11II‐g). Moreover, the DSC‐TENG was also utilized for real‐time human movement monitoring (e.g., walking, running, and jumping), with the information relayed via Wi‐Fi to a smartphone interface for Internet‐of‐Things (IoT) applications (Figure 11II‐h). These findings highlight the potential of the DSC‐TENG for developing scalable, multi‐purpose, self‐powered systems in smart electronics, security, and human‐machine interfaces [163].

These studies collectively highlight the transformative potential of MXene‐incorporated hydrogels and polymer composites for developing piezoelectric and triboelectric nanogenerators for next‐generation wearable health‐monitoring applications.

Moreover, the summarized studies on the recent MXene‐Nanogenerators‐based Wearable Health Monitoring devices are listed in Table 3.

TABLE 3.

MXene‐nanogenerators‐based wearable health monitoring devices.

Composition	Sensing mechanisms	Application	Performance	Refs.
MXene/polyurethane + glycerol	Planar strain sensing	Wrist & finger motion tracking	GF: 83.7, range: ±60%, accuracy: ±10°	[198]
MXene‐Au@Ag NPs/PVA hydrogel	SERS sensing	Sweat biomarker & pH monitoring	Creatinine: 2.7×10⁻⁹ M, Uric acid: 3.6×10⁻⁸ M, R²: 0.993/0.997	[199]
MXene@PDA/PF127‐DA/Zn²⁺ hydrogel	Conductive hydrogel sensing	Motion & muscle signal monitoring	Response time: 0.089 s	[200]
Oxidized starch/gelatin/MBGNs/MXene (GOMM) hydrogel	Conductive multifunctional sensing	Strain, temperature, humidity, EMG & ECG monitoring	Conductivity: 5.05 mS/cm, adhesion: 53.49 kPa, degradation: 92% in 24 days	[201]
MXene/Ag heterostructure flexible film	Piezoionic sensor	Motion; CPR guidance	11.1 mV at 0.7% strain; >95% retention over 13 000 s	[202]
Ti3C2Tx/PVP electrospun nanofibre membrane	Capacitive pressure sensor	Pulse; respiration; joint motion	0.5 kPa−1; 45/45 ms; 9 Pa; 8000 cycles	[203]
MXene/MWCNT electronic fabric mask	Humidity sensor	Real‐time respiration	265% response at 90% RH; 7% variation under stretch	[204]
MXene/CNT/PEDOT: PSS facial‐mask film	Thermoelectric sensor	Respiration rate; heart‐rate integration	Reliable RR sensing; 2.4× tensile strength; 59 dB EMI	[205]
Ti3C2Tx/TiO2/peptide wireless facemask	Wearable gas sensor	Breath acetone; lipid metabolism	BrAC detection down to 0.31 ppm; wireless tracking	[206]
Ti3C2Tx integrated pressure‐humidity patch	Dual‐mode sensor	Respiratory pattern; sweat, joint motion	1878.05 kPa−1; 0.67%(%RH)−1; 3.46/1.50 s	[207]

4.2. Smart Textiles and E‐Skin

The combination of piezoelectric and triboelectric sensors with textile substrates or artificial skin enables the fabrication of skin‐conformable sensors that can record motion, pressure, and other biophysical signals [208]. The inherent flexibility, stretchability, and biocompatibility of substrates make them suitable for long‐term wear, ensuring user comfort while maintaining high sensitivity and reliability under dynamic conditions [209].

Electrospun nanofibers are promising for flexible piezoelectric sensors, but producing multifunctional, high‐sensitivity devices remains a major challenge [210]. In this context, Huang et al. reported electrospun PAN/MXene/ZnS: Cu nanofibers. The ZnS: Cu/MXene synergistic reaction promoted the planar zigzag conformation of PAN, thereby enhancing ferroelectricity, mechanical strength, and energy storage efficiency (94.05%) [211]. Chen et al. developed a skin‐mountable wearable pressure sensor comprising a PET fabric covered with ZnO nanorods and MXene nanosheets to circumvent the requirements of the traditional piezoelectric thin films. This composite exhibited high sensitivity (53.22 kPa^{− 1}), fast response times, and high mechanical stability. The sensor was effectively used to record a variety of physiological signals, such as joint bending and pulse detection [212].

Zhang et al. fabricated composite nanofiber membranes by electrospinning poly(vinylidene fluoride) (PVDF) and augmented with different amounts of MXene and ZnO, which significantly improved the piezoelectric performance of PVDF. Notably, the core‐shell PM/PZ membrane exhibited a distinct linear voltage response to applied pressure and bending, making it highly suitable for use as a wearable sensor [213]. Fatemeh Mokhtari et al. developed acoustic energy harvesters based on electrospun PVDF‐TrFE on fabric‐based electrodes coated with 2D Ti₃C₂T_x MXene flakes to increase polarization and electromechanical performance. The resultant lightweight, flexible devices exhibited a high sensitivity of 37 VPa^{− 1} over the frequency range of 50 to 1000 Hz and sound levels of 60 to 95 dB, outperforming previous PVDF‐based sound harvesters. Achieving an output power of 19 mW/cm³ at 200 Hz and 95 dB, this technology demonstrates high potential for powering miniature electronics, such as implanted biomedical devices, wearables, and Internet of Things (IoT) applications [214].

Huang et al. developed a high‐performance piezoelectric sensor (PAN/MXene/PDA@ZnO‐5) designed for smart wearables. The sensor exhibited outstanding voltage sensitivity (28.56 V/N), a fast response and recovery, and strong mechanical stability. The sensor's flexibility and conformability also favor its integration with wearable technology for real‐time health monitoring. Huang et al. also outlined the preparation of PDA@ZnO through a Tris‐buffered reaction of dopamine hydrochloride, highlighting the importance of polydopamine in improving the functional characteristics and applications of ZnO in wearable physiological monitoring, as shown in Figure 12I [215].

FIGURE 12.

Application of MXene‐based PENG textiles for wearable physiological monitoring. (I) Schematic representation of the fabrication, functional mechanisms and Application of the PAN/MXene/PDA@ZnO‐5 piezoelectric sensor, Reproduced with permission [215]. Copyright 2024, Elsevier B.V. (II) Manufacturing process of a pliable, air‐permeable electronic sensor through the integration of MXene nanosheets and AgNWs onto chitosan‐coated electrospun elastomeric substrates, facilitating highly sensitive healthcare monitoring and intelligent photothermal therapy. Reproduced with permission [216]. Copyright 2024, Elsevier Ltd.

Chao et al. proposed a simple technique to develop a flexible, breathable, and antibacterial electronic sensor by attaching conductive MXene nanosheets and silver nanowires (AgNWs) onto chitosan‐coated electrospun elastomeric materials (Figure 12II). The resultant sensor had a very high sensitivity (gauge factor up to 4720), a wide strain range (approximately 120%), a low detection limit (approximately 0.0645%), and long‐term reliability, all enabled by reversible slippage of the conducting material within the nanofiber network [216]. Duan et al. introduced a smart data glove integrating MXene‐modified textile sensors and an adaptive machine learning model. The glove achieved gesture recognition accuracy of up to 99.5% for 14 gestures and maintained 98.1% accuracy when expanded to 20 gestures. The system featured local model updates without external computation and demonstrated real‐time wireless control of robotic operations, showcasing its potential for human‐machine interaction and wearable robotics [217]. Yousaf et al. fabricated composite piezoelectric nanogenerators using PVDF, ZnO nanorods, and Ti₃C₂‐MXene. The addition of MXene and ZnO increased the electrical conductivity, resulting in high output performance: an open‐circuit voltage of 16.3 V, a current output of 413 µA, and a power density of 1.74 W/m². These devices were capable of driving LEDs and hygrometers, thereby suggesting their viability for practical energy harvesting and wearable electronics [218].

Recent advancements in triboelectric nanogenerators (TENGs) have highlighted the need for micro‐capacitor formation and dielectric enhancement to improve charge accumulation [219]. Rana et al. reported an electrospun PVDF‐TrFE/MXene‐based TENG (EN‐TENG) that exhibits improved dielectric characteristics, with a fourfold increase in output performance and a peak power density of 4.02 W/m². The device was efficient at driving small electronics and also served as a self‐contained switch in smart‐home solutions, thereby emphasizing its potential for human‐machine interfaces [169].

Yi et al. proposed a composite of thermoelectric and triboelectric sensors based on Nb₄C₃T_x‐SNF composites as a multifunctional self‐powered sensor. The sensor exhibited a temperature sensitivity of −6.27 µV K^{− 1} and a triboelectric output voltage of up to 183.01 V, effectively utilized in respiratory monitoring masks and intelligent bionic grippers [220].

Peddigari et al. designed a flexible, self‐sustaining, ultrafast, high‐power‐density (SUHP) capacitor system that incorporates a PMN‐PT capacitor with a PZT‐based energy‐harvesting unit. Upon biomechanical bending, the system produced 172 V and 21 µA, harvesting energy at a density of 2.58 J/cm³ and releasing it within 480 ns. This approach achieved a peak power density of 5.38 MW/cm³ and represents a promising direction for powering high‐power, responsive, and flexible pulsed electronic devices [221].

Lang et al. reported ternary composite films of cellulose nanofiber/boron nitride/MXene (TCBM) via vacuum‐assisted filtration. These films exhibited a high thermal conductivity of 16.72 W m⁻¹ K⁻¹, which was 345% higher than that of TOCNF films. TENGs fabricated from these composites exhibited excellent triboelectric properties, with an open‐circuit voltage of 79.6 V, a short‐circuit current of 7.6 µA, and a peak power density of 272.5 mW m⁻². Interestingly, the devices remained thermally stable (with a maximum voltage of 55.8V) up to 270°C, indicating excellent thermal stability. Additionally, Figure 13I shows that the TCBM‐TENGs were efficient, self‐sustaining pressure sensors for real‐time tracking of human motion, making them an attractive method for capturing and harvesting energy in extreme environmental conditions [222].

FIGURE 13.

Application of MXene‐based TENG textiles for wearable physiological monitoring (I) Schematic illustration of the preparation and application of TCBM composite films for enhanced thermal conductivity and triboelectric performance in energy harvesting and self‐powered sensing, Reproduced with permission [222]. Copyright 2025, Elsevier B.V. (II) Demonstrations of the PVDF/MXene‐based TENG: (a) schematic of the TENG with rectifier circuit powering over 120 LEDs via gentle hand tapping; (b) capacitor charging/discharging curves for operating a sport watch (inset: hygrometer activation); (c) capacitor performance for powering a thermohygrometer sensor (inset: device activation); (d) schematic of the TENG as a self‐powered footstep motion sensor for automatic stair lighting; (e) photographs showing (i) fabricated footstep sensor, (ii) control circuitry, (iii) sensor and LED arrangement on stairs, and (iv) real‐time lighting demonstration; (f) durability test waveform showing stable voltage output over 60 000 cycles at 6 Hz input frequency, Reproduced with permission [223]. Copyright 2025, Elsevier B.V.

Bhatta et al. fabricated electrospun PVDF/MXene (Ti₃C₂T_x) composite nanofibers as an effective negative triboelectric layer for energy harvesting. The addition of MXene nanosheets enhanced the dielectric constant and surface charge density of PVDF nanofibers by 270% and 80%, respectively. Bhatta et al. utilized TENG as a self‐driven foot‐motion sensor to control automated step lighting, in addition to energy harvesting. As shown in Figure 13II, the TENG with a rectifier circuit shown in Figure 13II‐a drives over 120 commercial LEDs. Figure 13II‐b,c illustrates charging of the capacitor (10 µF to 2.25 V at 31 s; 22 µF at 50 s) to operate a sports watch and a hygrometer sensor. Figure 13II‐d demonstrates the scheme of the automated step‐lighting control system, and Figure 13II‐e–i–iv demonstrate the foot‐sized contact‐separation TENG system and a real‐time dynamically controllable lighting example. The system was environmentally friendly and did not require any external power to operate, unlike traditional motion sensors. This study highlights the potential of MXene‐modified PVDF nanofibers to support multifunctional, robust, and self‐powered sensing platforms in smart buildings and smart wearables [223].

Zhi et al. created a breathable, biocompatible, and antimicrobial all‐textile TENG by electrospinning MXene‐loaded PVDF nanofibers onto a nylon 6,6 fabric modified with silver (Ag) nanoparticles. The device showed a high output voltage (362 V) and current (38.5 µA); hence, it was able to charge the capacitor and light up many LEDs. Its tactile sensor array was highly sensitive to motion and pulse signals, with a high potential for use in wearable keyboards and tactile‐mapping systems [224].

To address scalability and conductivity challenges in fiber‐based electronics, Hao et al. developed a wet‐spun fiber composed of dopamine‐modified MXene and TPU (MMP fibers). These fibers exhibited excellent stretchability (675%), conductivity (4.32 S/cm), and durability under repeated deformation. A fabric‐based TENG constructed from MMP fibers achieved stable energy output and was used for real‐time motion sensing, presenting a scalable solution for intelligent textiles and wearable energy systems [225].

To enhance the performance of triboelectric nanogenerators (TENGs), Rana et al. fabricated a multilayered, flexible TENG (M‐TENG) incorporating MOF‐525 and an Ecoflex@Co‐NPC@MXene nanocomposite. MOF‐525 enhanced charge storage, while Co‐NPC and MXene facilitated efficient charge trapping and transfer, resulting in a 13‐fold increase in output. The device used a 3D‐printed microstructure with knitted fabric electrodes to attain humidity resistance and an extensibility of 245%. The system had a power density of 25.7 W/m² and a sensitivity of 149 V/kPa; hence, it could be used for biomechanical energy collection, tactile sensing, and gesture‐based virtual interfaces. These results support the feasibility of MXene‐based triboelectric nanogenerators as self‐powered, wearable systems [226].

Moreover, summarized studies on recent MXene‐based Smart Textiles and E‐Skin devices are listed in Table 4.

TABLE 4.

MXene‐nanogenerators‐based smart textiles and e‐skin devices.

Composition	Sensing mechanisms and materials	Application	Performance	Refs.
MXene‐coated cellulose yarns	Knitted cellulose yarn	Pressure/textile sensing	Knittable, washable; GF ∼6.02; up to ∼20%	[227]
MXene‐decorated multiresponsive textiles	Air‐laid paper (AP) + PDMS coating	Motion and thermal management	Sensitivity 5.78 kPa− 1; response 40 ms; photothermal 104.9 °C (1.25 W cm− 2);	[228]
AgNWs/MXene conductive‐network smart textile	Stretchable textile	Strain and thermal sensing	3D stretchable conductive network; personal healthcare and thermal management	[229]
PDA/MXene/PDMS smart textile	Elastic textile	Strain/wearable sensing	Waterproof, breathable, superhydrophobic; stable strain sensing	[230]
MXene/protein medical pressure sensor	Breathable degradable nanocomposite film	Pressure sensor	298.4 kPa− 1; sensing range up to 39.3 kPa	[231]
HBT MXene epidermal sensor	Hydrophobic bacterial cellulose/MXene film	Pressure/wet‐condition monitoring	Waterproof; 65.5 kPa− 1; 50 ms response; 0.57 Pa	[232]
Wrinkled PDMS/MXene triboelectric e‐skin	Flexible PDMS composite film	Tactile/e‐skin	Flexible, self‐powered, ultra‐sensitive tactile sensing	[233]
Cellulose–MXene film	Piezo‐capacitive & nanogenerator	Wearable sensor	1.12 kPa⁻¹, 3.3 V	[234]
PDMS/MXene‐EC TENG	Triboelectric nanogenerator	Energy Harvesting	295 V, 1.5 µA, 3 W m−2	[235]

4.3. Human‐Machine Interfaces (HMI)

The development of wearable electronics has been rapid, enabling real‐time tracking of physiological data and providing flexible, portable systems for monitoring motion and human‐machine interaction (HMI) [236]. These devices facilitate intelligent sensing, data‐based activity recognition, and seamless information exchange when integrated with the Internet of Things (IoT). Consequently, wearable electronics combined with the IoT are driving advancements in smart healthcare, gesture control, and ambient intelligence [237].

Human‐Machine Interface (HMI) devices based on MXenes have received considerable attention owing to their unique properties, such as electrical conductivity, mechanical flexibility, and surface chemistry [238]. Their large surface area, combined with tunable functional groups, enables strong coupling with polymeric materials and hydrogels, thus providing stretchable, flexible, and even skin‐compatible devices. Some examples of MXene‐based HMIs include motion detection, gesture control, tactile feedback, and biosignal monitoring systems with high SNRs and fast response times. Furthermore, their low power consumption makes them suitable for the design of soft robots, virtual reality, and even assistive devices [239, 240].

Researchers are actively exploring MXene for advanced HMI devices. For example, Shen et al. designed a conductive, biodegradable film using carboxymethyl chitosan and silk fibroin (CSF) for use in wearable triboelectric nanogenerators (CSF‐TENGs), which deliver outputs of approximately 165 V (open‐circuit voltage), 1.4 µA (short‐circuit current), and 72 mW/cm² (power density). In vitro degradation experiments with trypsin and lysozyme showed a 63.1% mass loss over 11 days, highlighting the material's environmental friendliness. The CSF‐TENG was implemented in an HMI, which enables real‐time hand recognition and correction, and was tested and proven to identify the letters F correctly and K. Figure 14a‐i–iii presents real‐time voltage signals for strokes “‐,” “/,” and “|” during letter writing. Figure 14b shows the identification and correction of letter F, with Figure 14c illustrating the standard stroke sequence. Figure 14d–h displays voltage trends and feedback mechanisms, enabling users to revise strokes in real time. The system highlights incorrect strokes, provides visual cues, and supports intelligent correction using LabVIEW analysis. Letters H and K were also successfully recognized and corrected, as shown in Figure 14h,i, demonstrating the system's robustness even with complex strokes like “<”. The CSF‐TENG‐based HMI offers high accuracy, sensitivity, and potential for applications in intelligent writing pads, calligraphy training, and AI‐integrated IoT devices [241].

FIGURE 14.

Real‐time handwriting recognition and correction using CSF‐TENG‐based HMI: (a) Electrical signals and stroke outputs for “‐”, “|”, and “/” with corresponding electrode activation (1–6); (b) writing results of letter “F” across different steps; (c) standard stroke sequence and schematic of letter “F” recognition; (d–f) voltage signals during letter “F” writing; (g) structure and fabrication of CSF‐TENG; (h,i) signal outputs and schematic illustrations for recognition and correction of letters “H” and “K”. Reproduced under Creative Commons license [241]. Copyright 2022, Springer Nature.

Long et al. addressed key challenges in hydrogel‐based electronics by developing a triple‐network hydrogel (MPP‐hydrogel) composed of Ti₃C₂Tx MXene nanosheets and dual polymer chains (PAM and PVA). The MXene acted as a cross‐linker, enhancing conductivity while forming double electric layers (DELs) with water molecules. When integrated into a triboelectric nanogenerator (MPP‐TENG), the hydrogel enhanced the device's electrical performance and facilitated precise detection of low‐frequency human movements, rendering it suitable for biomedical applications [242].

Hui et al. introduced a polyacrylamide/chitosan/MXene (PCM) hydrogel with gradient porosity and tunable softness, fabricated via phase‐transition‐induced foaming. MXene played a crucial role in enhancing gelation, ion transport, and charge modulation. The resulting PCM foam (PCMF) tactile sensor exhibited high sensitivity (4267 kPa^{− 1}) and a wide pressure detection range (up to 100 kPa). Demonstrations included gesture‐based robotic arm control for swab sampling and electric car navigation in a maze game, integrating visual feedback and machine learning for accurate command recognition [243].

Zhang et al. developed a highly stretchable, adhesive, and self‐healing ionic hydrogel (PTSM) composed of polyacrylamide (PAM), tannic acid (TA), sodium alginate (SA), and MXene. The PTSM hydrogel demonstrated outstanding mechanical performance, including a strain limit exceeding 4600% and a high gauge factor of 6.6 for strain sensing. When encapsulated in silicone rubber, the resulting PTSM‐based triboelectric nanogenerator (PTSM‐TENG) achieved a power density of 54.24 mW/m². A glove‐based human‐machine interface (HMI) system was built using PTSM‐TENGs, enabling real‐time gesture tracking and robotic hand manipulation. Enhanced by machine learning, the system achieved 98.7% object recognition accuracy using triboelectric contact signals. These findings highlight the promise of hydrogel‐based TENGs in smart sensing, HMI, and soft robotics [244].

S. Zhang et al. proposed the design of a monolayer non‐contact triboelectric nanogenerator by integrating multi‐walled carbon nanotubes and MXene into an Ecoflex‐based triboelectric layer, referred to as the MME‐film. The device demonstrated high flexibility and stretchability of up to 700%, while displaying robust mechanical endurance. Additionally, a human‐machine interaction system was developed (Figure 15I‐a) comprising NC‐M−TENG units, an Arduino microcontroller, HC‐12 wireless modules, and a robotic arm. Voltage signals produced by six NC‐M−TENG units organized in a 2 × 3 array guided robotic gestures (Figure 15I‐b), which were well‐performed by a robotic arm with high precision (Figure 15I‐c). Thus, this system demonstrated that NC‐M‐TENGs can be used for advanced non‐contact interfaces for robotics, public infrastructure, and virtual reality applications [245].

FIGURE 15.

Application of MXene‐based PENG and TENG for human machine interface (HMI), (I) Demonstration of wireless robot control using a human‐machine interaction system based on an arrayed NC‐M−TENG. (a) Schematic of the system architecture, where tactile signals from the NC‐M−TENG array are processed by a microcontroller unit (MCU) to enable gesture‐based control. (b) Analog voltage outputs from individual NC‐M−TENG units are recorded via MCU channels, illustrating the system's responsiveness to touch inputs. (c) The robotic arm performs six distinct digital gestures in accordance with the control instructions, demonstrating the system's capability for precise, wireless motion control. Reproduced with permission [245]. Copyright 2025, Elsevier B.V. (II) The self‐powered STTS is demonstrated in interactive control applications. (a) In the balance table game, finger movements, thumb and pinky for lateral tilt, index and middle for forward/backward motion, are used to control the table's orientation. (b) The STTS enables robotic hand control by converting finger motions into voltage signals for gesture replication. (c,d) The test circuit setup comprises an Arduino board, servo motors, and signal‐processing components, enabling real‐time translation of tactile input into mechanical response. This setup highlights the STTS's effectiveness in wearable human‐machine interfaces. Reproduced with permission [246]. Copyright 2022, Elsevier Ltd.

Zhang et al. integrated the MXene/Ecoflex nanocomposite with conductive fabric electrodes to design a self‐powered toroidal triboelectric sensor (STTS) for flexible human‐machine interaction. The triboelectric performance was enhanced by a 3D‐printed pyramidal structure that eliminated the need for spacers, while a TPU‐based glove design ensured wearability and comfort. Additionally, Figure 15II details STTS applications for controlling a balance table and a robotic hand. In more detail, Figure 15II‐a demonstrates the control of the index, middle, thumb, and pink movements. Figure 15II‐b illustrates the robotic hand control using an Arduino environment, where an Arduino‐based circuit processes voltage signals from finger movements (Figure 15II‐c,d) to actuate servo‐driven finger bending. The ring shells of the glove had ergonomic dimensions, and differences in electrical output across the fingers were analyzed to confirm sensing consistency. These results underline the potential of STTS for wearable, artificial‐intelligence‐integrated HMI systems [246].

Z. Sun et al. developed an MXene and CNF‐based MCM‐TENG through the layer‐by‐layer self‐assembly technique. The MCM film used in this device simultaneously serves as both the triboelectric layer and the electrode, with significant benefits from its excellent conductivity and mechanical robustness. The optimized device can produce an output voltage of about 90 V at 2 Hz, which was adequate for operating flexible ACEL displays and therefore has promising applications in self‐powered display and HMI systems [247].

Together, these investigations underscore the adaptability and potential of MXene‐based nanogenerators for the development of self‐powered platforms for smart sensing, wearable devices, and interactive electronics. Moreover, the summarized studies on the recent MXene‐based HMI devices are listed in Table 5.

TABLE 5.

MXene‐based nanogenerators for human–machine interfaces.

Device/material system	Interaction mode	Signal/output type	Recognition/control capability	Electronics/end‐use	Refs.
MXene/PVA hydrogel TENG	Motion/handwriting	Stretchable to 200%; monotonic short‐circuit‐	High‐precision written‐stroke recognition	Wearable movement monitoring	[248]
Ti₃C₂Tx MXene/chitosan actuator	Moisture responsive	Unidirectional bending	Non‐Contact Control	Keyboard, robot, respiratory sensor	[249]
Holey MXene 3D tactile sensing system	Pressure/tactile interaction	Pressure + energy‐storage signal	User behavior recognition	Smart access control, flexible electronics	[250]
MXene/P(VDF‐TrFE) charge‐generating layer + charge‐trapping nanofibrous layer TENG	Gait/activity	Power density 19 W m− 2	Deep‐learning user identification and activity recognition; 99% accuracy	Shoe‐insole wearable AI sensor	[251]
V2CTx/silicone serpentine TENG	Sign‐language gestures	Enhanced surface potential and charge density	Sign‐language interpretation	Wearable self‐powered sensor	[252]
MXene/leather triboelectric tactile sensor	Tactile touch	Triboelectric tactile signals	Wireless robotic‐hand interaction	Flexible HMI/tactile interface	[253]
Ti3CNTx/PVA nanofiber‐membrane TENG	Human–computer interaction	Peak power density 5.5 W m− 2; 96% output retention after 10 000 cycles	HCI‐oriented self‐powered sensing	Flexible HCI platform	[254]
MXene‐enabled hybrid triboelectric–electromagnetic sensor HTES	Touchless + tactile robotic perception	Voltage for touchless mode; current for tactile mode	CNN classification of material, shape, and hardness: 99.5%, 97.9%, 98.6%	Robotic hand	[255]
Perfluorocarbon‐chain Ti3C2Tx MXene triboelectric sensor	Hand motion/letter input/proximity	Power density 363 mW m− 2	Letter recognition; non‐contact distance detection	Self‐powered triboelectric interface	[256]

4.4. Sports and Fitness Tracking

Sports and health monitoring is a crucial area where self‐powered health monitoring sensors can play a significant role, as sports require continuous, real‐time monitoring of body motion and activity without frequent battery changes. One way to achieve this task efficiently and conveniently is to use piezoelectric and triboelectric nanogenerators that convert biomechanical energy generated during workouts into electrical signals [257, 258].

The unique characteristics of MXene‐based PENGs and TENGs significantly advance self‐powered sensors for sports and fitness tracking applications, offering high flexibility, low weight, and mechanical durability, thereby facilitating their incorporation into smart fabrics, athletic footwear, wristbands, and protective equipment [172, 259]. The high sensitivity of these devices enables them to monitor exercise strength, frequency, and posture, which are critical for assessing athlete performance and preventing injuries. Furthermore, the ability to operate independently enables data acquisition over extended periods during training and competitions without requiring additional power sources [260, 261].

Several works have reported mechanical energy harvesting from sports motion to power wearable sensors for long‐term physiological monitoring. For example, Wu et al. developed a flexible PS/MXene‐based TENG with a drum structure. With an optimized PS content, the device developed 141 V and 5.9 µA output and 123 µW power at 50 MΩ. Due to its flexibility, it can monitor full‐body motion in football players and therefore has potential applications in monitoring athletic performance [262].

Yang et al. reported a PDMS@MXene@BaTiO₃‐based TENG, named PMB‐TENG, using the ion‐treated PET and a dielectric regulation method. The developed TENG displayed remarkably enhanced output: 164.4 V, 4.08 µA, and 2.4 W/m². It was employed for posture monitoring during basketball activities, advancing the development of sports monitoring [263]. Wang et al. presented a low‐cost fiber‐glass cloth TENG (FC‐TENG) with a laminated cotton fabric, achieving an output of 172.7 V, 30.4 µA, and 158.7 mW/m². Integrated into football shoes, it enabled real‐time gait and motion analysis, fall detection, and performance optimization without external power sources [264].

Conventional fatigue monitoring techniques are usually costly and invasive [265]. To address this issue, Liu et al. proposed a biobased pulp‐wool triboelectric nanogenerator (PW‐TENG) integrated with a heart rate strap and an inertial measurement unit (IMU) to enable multimodal, non‐invasive fatigue monitoring. This system provides a practical approach to personalized training and health management in sports. Moreover, the overall summary is illustrated in Figure 16I, which explains the multimodal fatigue analysis using PW‐TENG technology. It includes molecular structures of BaTiO₃ and graphite, a schematic of the flexible PW‐TENG device, and a runner equipped with wearable sensors. 3D scatter plots visualize PCA results across fatigue stages (Starting, Middle, Final), demonstrating the system's capability to detect motion‐induced fatigue [266]

FIGURE 16.

Application of MXene‐based PENG and TENG for sports and fitness tracking. (I) Overview of multimodal analysis of motion fatigue using PW‐TENG technology integrated into footwear and wearable sensors. The molecular structures of BaTiO₃ and conductive graphite are shown alongside the flexible PW‐TENG material. Real‐time motion data from a runner is analyzed using PCA‐based 3D scatter plots to identify fatigue stages. Reproduced with permission [266]. Copyright 2025, American Chemical Society. (II) showcases the multifaceted advantages of the mechanoluminescent triboelectric sensor (MTS) for tracking sports status while wearing a technology‐enabled outfit during outdoor sports activities. The model in Figure (a) schematically displays the incorporation of the MTS into smart outfits for engaging directly in outdoor sports. The figure in (b) displays the voltage generated by the sensor in response to differences in body weights. In contrast, the figure in (c) shows its sensitivity to changes in the angles at the knee joint, with the voltage rising to a maximum of 40 V at 45° compared to the initial 32 V at 30°. The figure in (d) verifies the stability of the electrical current in the sensor, regardless of the frequency steps used during the activity at 1.5, 2, and 2.5 Hz. The figure in (e) illustrates the pulsed green fluorescence emitted by the MTS during nighttime activities, significantly enhancing visibility and safety for the wearer. The figure in (f) shows the data acquisition system for the wearable technology, which incorporates charge amplification, filters, and a Bluetooth module for data transmission. The final figure in (g) displays the overall model for the fully integrated wearable technology, which transmits data on the wearer's motion to the mobile phone, thereby demonstrating the practical potential of the MTS technology for a real‐time, self‐sustaining monitoring system for smart sportswear. Reproduced with permission [267]. Copyright 2025, American Chemical Society.

Chen et al. fabricated an MTS using ZnS/Cu and triboelectric nanogenerators, along with breathable silver fibre electrodes, which were then integrated into yoga pants to enable real‐time joint monitoring with light emission. ZnS/Cu‐doped silicone rubber was prepared to enhance dielectric properties and output signals. The MTS translates joint flexion into pulsed green fluorescence and electrical signals, thus monitoring motion and ensuring user safety. Additionally, Figure 16II‐a–c shows that the sensor monitors knee‐bending angles at different degrees. The voltage outputs are 32 V at 30° and 40 V at 45°, which maintain high repeatability across every cycle. Figure 16II‐d indicates that the electrical output is consistent across the step frequencies from 1.5 to 2.5 Hz, confirming reliable output under dynamic conditions. Figure 16II‐e shows an MTS emitting synchronized fluorescence in motion under dark conditions. Figure 16II‐f illustrates the integration of a charge amplifier, a filter (a Butterworth low‐pass filter with a cutoff frequency of 10 Hz), and a Bluetooth transmitter (STM32, HC‐05) for acquiring signals wirelessly. The conditioned signals can then be transmitted to mobile devices for real‐time motion analysis, as illustrated in Figure 16II‐g. This system provides an efficient means of harnessing mechanical energy and points to a promising future for MTS‐based smart clothing in wearable applications, such as the monitoring of human motion and nighttime safety [267].

Moreover, the summarized studies on the recent MXene‐based Sports and Fitness tracking are listed in Table 6.

TABLE 6.

MXene‐based nanogenerators for sports and fitness tracking.

Device/material system	Body location/sport use	Motion/parameter tracked	Output performance	Functional outcome	Refs.
P(VDF‐co‐HFP)/MXene PM‐TENG	Mask + shoe; basketball	Respiration, gait, posture	V oc 225 V; Q sc 180 nC; Pmax 1.68 mW	Fitness‐load tracking; gait‐based training aid	[268]
PDA/MXene/NIPAM hydrogel PMN‐TENG	Elbow + knee; basketball	Bending, lifting, walking, running, jumping	V oc 16 V; I sc 0.47 µA; Q sc 25 nC	Joint‐state feedback in training	[269]
TPU/MXene/carbon PT‐TENG	Joint/skin; Tai Chi	Posture + heart rate	Q sc 104.65 nC; Pmax 132.34 µW	Health Monitoring	[270]
PDMS/MXene flat PM‐TENG	Glove/impact surface; boxing	Jab, straight, hook punches	V oc 278 V; J sc 8.46 µA cm− 2; Pmax 4.44 mW cm− 2	Punch classification; technique feedback	[271]
MXene/PVDF‐HFP fibre MC‐TENG	Knee; ACL sport screening	Tibia‐knee relative displacement	V oc 160 V at 10 N; min pressure 0.01 N	Early ACL self‐screening: injury prevention	[272]
PI/MXene PC‐TENG	Paddle; table tennis	Impact force, strike dynamics	V oc ∼105 V; Q sc 63.14 nC; Pmax 1.16 mW	Real‐time stroke/force analysis	[273]
MXene double‐network hydrogel MD‐TENG	Foot/joints; football	Foot pressure, joint movement	V oc 491.98 V; I sc 75.41 µA; Qsc 83.93 nC; Pmax 2.54 mW	Performance optimisation; injury prevention	[274]

4.5. Wearable Therapeutics and In Vivo Applications

Wearable therapeutics and biomedical implants in vivo constitute an emerging field of self‐powered electronics, where PENGs and TENGs based on MXenes offer unique benefits. In such applications, devices need to be continuously and reliably powered under physiological conditions that involve mechanical stress. MXenes are promising candidates for use as functional materials in future therapies due to their high electrical conductivity and mechanical flexibility [275, 276, 277].

The application of MXene‐based PENGs and TENGs for wearable therapeutics is especially promising, as energy derived from natural human movements, such as breathing, muscle motion, joint activity, or cardiac function, can be harvested and converted into electrical stimuli [278]. Electrical stimuli can either be used to generate power for therapeutic devices or applied to living tissue. For instance, the nanogenerator can provide electrical stimulation to manage pain, rehabilitate muscles, or heal wounds, thereby eliminating the need for an external energy source [279].

For implants and in vivo systems, the biocompatibility and flexibility of the materials are important. The biocompatibility of MXenes, when functionalized or coated, is favorable, allowing them to be used in biomedical applications on a temporary or long‐term basis. In vivo, the energy produced by the MXene‐based nanogenerator through physiological motions, such as heartbeats, diaphragm contractions, or GI tract motion, can power sensors or provide local electrical stimulation [108, 280, 281].

Recent research underscores the potential of MXene‐based nanogenerators for therapeutics and in vivo biological applications, owing to their ability to generate electrical stimulation. In their pioneering study, Meiru Mao et al. introduced a novel wearable TENG based on MXenes to promote wound healing by converting biomechanical energy into an electric field, in combination with photothermal therapy [278].

Yi Fu et al. reported MXene/PVDF ferroelectric nanocomposite membranes that can be used in PENGs for therapeutic purposes. These MXene‐containing membranes can attract and differentiate osteogenic cells through their natural surface potential, ultimately promoting bone regeneration in living organisms [282]. Venkatesan et al. described a TiO₂‐MXene charge‐trapping triboelectric nanogenerator that combined biomechanical sensing with electrical‐stimulation‐assisted wound healing [283]. Ju et al. demonstrated a wearable electrostimulation‐augmented ionic‐gel photothermal patch doped with MXene for skin tumor treatment, further underscoring the therapeutic adaptability of MXene‐based wearable systems [284].

Feng et al. designed an electroactive nanosystem based on Ti₃C₂Tx MXene that could respond to the native electric field generated by the wounded site and convert the signal into a self‐driven microcurrent without an external power source. With high electrical conductivity, permittivity, and charge, the system was successfully applied to regulate wound bioelectricity, thereby increasing fibroblast function, collagen synthesis, angiogenesis, and re‐epithelialization [285]. H Yu et al. developed a MoS₂‐based wearable TENG device for wound healing and highlighted the potential of nanogenerator‐generated electricity for this application [286].

Zhao et al. reported an extremely stable MXene‐based electronic skin by functionalizing Ti₃C₂T_x MXene using PVA via hydrogen bonding. According to Figure 17I‐a, the introduction of PVA ensured optimal strain sensitivity and pressure sensing, which could be attributed to the high‐pressure sensitivity of 164.75 kPa^{− 1} reported in the study. As shown in Figure 17I‐b, the material exhibited excellent stability against humidity, as evidenced by the low weight loss upon immersion in water, acidic, and basic media for 7 days. In addition, the material showed promising results for in vivo applications, owing to its excellent biocompatibility [287].

FIGURE 17.

Application of MXene‐based PENG and TENG for wearable therapeutics and in vivo applications (I) PVA/MXene hybrid thin film (a) Cross‐linked PVA/MXene network structure. (b) Weight loss of PVA/MXene films after 7‑day immersion, showing enhanced chemical stability (n  =  3). Reproduced with permission [287]. Copyright 2021, Elsevier Ltd. (II) Schematic illustration of piezoelectric‑assisted nerve repair and regeneration. Reproduced with permission [288]. Copyright 2023, American Chemical Society.

H. Zhang et al. proposed a novel scaffold for in vivo nerve regeneration by incorporating MXene into a piezoelectric nanogenerator. The SF/PVDF‐HFP/MXene electrospun nerve guide can deliver safe, low‐intensity electrical stimulation, and MXene greatly improves the piezoelectric output (∼100 mV), mechanical properties, and antimicrobial properties. In vitro studies showed that ultrasound‐activated piezoelectric signals could promote Schwann cell proliferation. The SF/PVDF‐HFP/MXene electrospun conduit significantly improved axonal elongation, myelination, and recovery of motor‐sensory function in injured rat sciatic nerves. Additionally, as shown in Figure 17II, the body's motion‐induced strain produced continuous piezoelectric signals, which activated Schwann cells to release neurotrophic factors (such as NGF and VEGF). Consequently, the nerve fibers were guided by the band of Büngner, leading to functional nerve regeneration [288].

Moreover, the summarized studies on recent Wearable Therapeutics and In‐vivo Applications are listed in Table 7.

TABLE 7.

Summarized studies on MXene‐based PENG‐TENG for wearable therapeutics and in vivo applications.

Device/material system	Monitoring or therapeutic target	Therapeutic modality	Key outcome/translational relevance	Citations
US responsive piezoelectric PVA/PVDF/MXene hydrogel	Immunosuppressive breast tumor microenvironment	Piezoelectric stimulation + immunotherapy	Enhanced immunogenic cell death,	[289]
HOT‐TENG with PVDF/BaTiO3/MXene eskin patch	Wound healing	Triboelectric stimulation + MXene photothermal effect	∼450 % output enhancement; accelerated fibroblast proliferation/migration	[290]
Ultrasound powered battery free PTNG implant	Parkinson's disease (DBS)	Wireless electrical neurostimulation	Miniaturized soft implant enables programmable DBS in rats	[291]
POTEL conductive organohydrogel dressing	Wound healing	Electrical stimulation + NIR photothermal	Accelerated healing with antibacterial and sensing functions	[292]
MXene/RSF electroactive hydrogel	Bone regeneration	Electrical stimulation + piezoresistive sensing	Promoted osteogenesis, angiogenesis, and immune regulation under ES	[293]
Selfpowered P(VDFTrFE)/TBAC piezoelectric membrane	Wound healing	Mechanically‐activated electrical stimulation	Enhanced antibacterial activity	[294]
CoMOF/V2C MXenePDMS TENG	Motion sensing	Triboelectric sensing	Self‐powered joint monitoring and alert function	[295]
Injectable MXene‐based SCO@M hydrogel	Diabetic wounds	Injectable + NIR photothermal + immunomodulation	Accelerated healing via antibacterial and immune regulation	[296]
PVDF/MXene nanofibrous eskin	Wearable sensing	Piezoelectric sensing + NIR antibacterial	High‐performance sensing with on‐demand sterilization	[297]

5. Discussion

MXene incorporation into piezoelectric and triboelectric nanogenerators has emerged as an innovative approach for developing self‐powered wearable electronics and therapeutics, enabling the integration of power generation and sensing functionalities within flexible mechanical platforms. In all the literature discussed here, MXenes have been shown to play multifunctional roles, acting as electrical conductors, dielectric materials, charge‐trapping layers, and interfacial coupling agents, which makes MXene‐based nanogenerators distinctly different from polymer‐ and ceramic‐based devices.

In the context of PENGs, MXenes primarily serve as interfacial polarizer promoters and nucleators of the beta phase, especially when used in conjunction with fluoropolymer composites such as PVDF and PVDF‐TrFE. The incorporation of MXene nanosheets enables a range of electrostatic interactions, hydrogen bonding, and electric‐field generation, resulting in effective dipole alignment without the need for high‐voltage poling of the composites. This approach improves the piezoelectric coefficient and the stability of the generated output while also simplifying the fabrication process, an essential factor for large‐scale manufacturing.

For TENGs, MXenes have a more diverse functional range than any other material studied to date. The high electronegativity and controllable surface termination characteristics place them in a higher region of the triboelectric series. The metallic character of MXenes enables high charge‐transfer efficiency when used as an electrode material or triboelectric layer. More critically, by creating MXene structures such as aerogels, hydrogels, fabrics, or fibrous mats, the design can provide micro‐ and nanoscale interfaces that increase contact area and charge density without sacrificing mechanical flexibility.

One of the major advantages of nanogenerators based on MXene materials discussed in this review is their structural adaptability. Electrospun nanofibers, ice‐templated aerogels, printable inks, and textile‐based systems have been designed that allow such devices to be shaped to fit the skin, clothing, or soft tissue structures without losing their ability to generate electricity. The versatility of this approach enables these devices to operate successfully across a range of applications, including continuous physiological monitoring, electronic skins, gesture recognition, sports analysis, and therapeutic agents. Among the most intriguing examples are multi‐functional systems, where nanogenerators are used for various purposes, from sensing to antibacterial action.

There are significant breakthroughs described above, but the common trends persist in the reported performance limitations and challenges. The first is oxidation, which affects the long‐term electrical stability of both PENGs and TENGs. Although several approaches, such as surface passivation, polymeric encapsulation, incorporation of antioxidant agents, and utilization of heterostructure configurations, show promising results in short‐term experiments, their performance under prolonged mechanical stimulation and physiological exposure requires further investigation. Sequentially, even though MXenes exhibit outstanding mechanical strength initially, fatigue‐induced interfacial slippage and microcracking continue to affect the operational lifespans of MXene‐containing PENGs and TENGs in practical applications.

In terms of practical applications, MXene‐enabled nanogenerators are well‐suited to the development of data‐driven, intelligent wearable devices. There are several examples of nanogenerators that can provide wireless communication, local processing of collected signals, or even pattern recognition using machine learning. Nevertheless, for most prototypes, the computations and data training were done externally. The key advantage of such systems in the future would be their ability to implement closed‐loop, self‐powered systems in which all processes, including energy generation, sensing, and data analysis, are combined.

All the work described above indicates that MXenes not only improve the performance of various PENGs/TENGs but also enable the creation of fundamentally new nanogenerator systems. Indeed, the multifunctionality of MXenes enables PENGs/TENGs to become more complex devices that can both generate energy and sense the environment. Such a combination will make the development of PENG/TENG‐based technologies more challenging, as it will require integrating materials science, electronics, and system approaches.

6. Challenges and Future Perspectives

MXene nanogenerators have immense potential for wearable, personalized monitoring and therapeutics, but certain problems must be addressed first to ensure practical application and sustainability. One such problem is the oxidation of MXenes, which makes the devices highly susceptible to corrosion when exposed to air. Another critical challenge is maintaining a consistent level of output signals even during exercises that involve perspiration, which could affect the device's sensitivity and longevity. Applying a hydrophobic layer and integrating an encapsulating substance to enhance flexibility are possible solutions to this problem.

The piezoelectric or triboelectric performance has also been observed to diminish over time in some nanogenerators due to improper dipole orientation or dispersed fillers. Measures can be taken to address poor performance by optimizing dipole orientation, adjusting the filler ratio, or improving interfacial interactions. Biocompatibility issues in wearable devices or implants remain unresolved, although improved alternatives are anticipated from future in vivo experiments and biodegradable MXenes.

Despite considerable progress in the design of MXene‐based PENGs and TENGs, several drawbacks remain that prevent their practical implementation in the clinic or industry. It is essential to identify the limitations and develop efficient approaches to promote further investigation of MXene‐based energy harvesters. An important limitation that has not yet received sufficient attention from the scientific community is the lack of uniform criteria for evaluating the performance of MXene‐based nanogenerators. The electrical characteristics, including open‐circuit voltage, current density, power density, and sensitivity, are usually reported without detailed information on the applied mechanical stimuli, electrode shapes, and load resistances. In addition, the impact of environmental factors on device performance has not yet been properly assessed. Therefore, defining standardized criteria for evaluating the output performance of MXene‐based nanogenerators is an important and urgent task for the scientific community.

Another critical area that needs attention is the lack of a proper study on stability and degradation over a longer period, especially in physiological or biological conditions. Although initial demonstrations show excellent electrochemical performance, robust measurements of MXene oxidation, delamination at interfaces, and fatigue properties over longer periods remain lacking. When discussing the use of devices in therapeutics or wearable electronics, the system must operate stably under exposure to sweat, humidity, deformation, and repeated stress for weeks or even months. When talking about implantable or in vivo devices, the lack of studies on biostability, including the oxidation of MXenes, leaching, and electric drift in biological solutions, becomes a critical point. There is also limited information about the safety and biocompatibility of MXene‐based nanogenerators in vivo. Although in vitro studies reveal relatively low toxicity when MXenes are modified with a suitable surface layer or encapsulated in polymers, in vivo studies are limited and scattered. Key issues to be addressed include the long‐term fate of MXenes, the effects of gradual oxidation or decomposition on adjacent tissues, and the immune response to MXenes. Future research should focus on developing a standardized framework to evaluate the performance, biocompatibility, and functionality of MXene‐based nanogenerators in vivo.

From a manufacturing perspective, scalability and process reproducibility remain unsolved bottlenecks. The majority of efficient PENGs and TENGs employing MXenes are based on lab‐scale synthesis methods, such as vacuum filtration, drop‐casting, or batch electrospinning, which pose significant challenges for scaling up to large‐scale production. In addition, controlling the size of MXene flakes, their chemical termination, dispersity, and the strength of interlayer bonding at an industrially viable scale is a challenge. Future research efforts should focus on establishing correlations between process parameters, device structure, and its properties.

Lastly, the full potential of MXene‐based nanogenerators can be realized only through better coupling of these devices with data‐related technologies and artificial Intelligence. Some studies have demonstrated proof of concept in gesture recognition and physiological sensing with artificial intelligence assistance, but most systems still rely on limited data and offline processing. The next important development in this field would be the design of self‐powered, closed‐loop systems in which the MXene nanogenerators not only generate energy but also detect physiological signals and pre‐process the data.

In conclusion, for the development of future MXene‐based PENGs and TENGs, the improvement of materials aside from other innovations must not be the only focus of research; rather, efforts should also be made to resolve some of the basic issues that still need to be addressed, such as standardization, durability testing, manufacturing processes, and data processing.

7. Conclusion

MXene‐based piezoelectric and triboelectric nanogenerators have fundamentally reshaped the landscape of self‐powered wearable electronics, offering efficient energy harvesting and high‐fidelity physiological sensing in flexible, skin‐compatible platforms. The unique combination of high electrical conductivity, versatile surface chemistry, and mechanical compliance enables MXenes to function simultaneously as active charge‐generating layers, electrodes, and interfacial modifiers in PENGs and TENGs. Recent advances demonstrate multifunctional systems capable of continuous health monitoring, motion tracking, human‐machine interaction, sports analytics, and wearable or in vivo therapeutics without reliance on external power sources.

Despite these advances, several critical challenges remain, particularly regarding long‐term environmental stability, biocompatibility under prolonged physiological exposure, and scalable, cost‐effective manufacturing. Addressing these issues will require interdisciplinary approaches that integrate materials engineering, device physics, bioengineering, and system‐level design. Looking ahead, integrating MXene‐based nanogenerators with artificial intelligence, edge computing, and green fabrication strategies is expected to unlock intelligent, adaptive, and sustainable wearable systems. Collectively, MXenes are poised to become foundational materials for next‐generation personalized monitoring and therapeutic technologies.

Author Contributions

Bangul Khan: conceptualisation, writing‐ original draft preparation, writing‐ reviewing and editing. Rana Talha Khalid and Muhammad Hasan Masrur: writing‐ original draft preparation. Bilawal Khan, Mohamed Elhousseini Hilal, and Mohamed Elgendi: writing‐ reviewing and editing, visualisation. Bee Luan Khoo: conceptualisation, writing‐ original draft preparation, writing‐ reviewing and editing, visualisation, and supervision.

Funding

The authors have nothing to report.

Conflicts of Interest

The authors have nothing to report.

Data Availability Statement

Data sharing not applicable to this article as no datasets were generated or analysed during the current study.