Polymer/MXene Composite-Based Flexible Pressure Sensors: From Mechanisms and Structural Designs to Emerging Applications

Abstract

Wearable electronics are increasingly utilized in mobile healthcare, human-machine interfaces, and portable energy systems due to their inherent flexibility and stretchability. Recently, MXene, a two-dimensional material, has emerged as a transformative material for flexible sensors, owing to its exceptional electrical conductivity, mechanical flexibility, hydrophilicity, and tunable surface chemistry. This review systematically summarizes recent advances in flexible pressure sensors based on polymer/MXene composites. The fundamental sensing mechanisms are elaborated, including piezoresistive, capacitive, piezoelectric, and triboelectric modes, and the rational selection of substrate materials, fabrication techniques, and structural design principles for high-performance sensors are comprehensively discussed. Furthermore, the article spotlights the promising applications of polymer/MXene-based sensors across a range of cutting-edge fields. Finally, the key challenges hindering their large-scale production and practical deployment are outlined to guide future research and accelerate the widespread adoption of polymer/MXene composites in flexible sensing technologies.

1. Introduction

Wearable electronics are rapidly reshaping personalized healthcare, human–machine interfaces, and soft robotics by enabling continuous monitoring of physiological and environmental signals under large deformation. Flexible pressure sensors are central to this vision, yet conventional devices based on rigid silicon chips and metal electrodes suffer from mechanical mismatch with soft tissues, limited conformability, and long-term discomfort during wear. Two-dimensional MXenes have recently emerged as promising building blocks for next-generation flexible pressure sensors owing to their high electrical conductivity, mechanical flexibility, and rich surface chemistry that enables tunable interfacial interactions and hybrid architectures. , The strategic engineering of structural dimensions and interfacial phases has emerged as a universal paradigm for maximizing device performance; this is exemplified by the precision electrochemical etching of III-nitride semiconductors, the rational porosity design of covalent triazine-based frameworks (CTFs), and the integration of synergistic phase boundaries or hexagonal morphologies in spinel-based energy storage electrodes. , Drawing inspiration from these advancements, the architectural optimization of 2D MXenes is equally vital for unlocking their full potential in physical sensing. When combined with polymers into composite systems, MXenes can be processed into fibers, films, foams, aerogels, and hydrogels that reconcile electrical performance with stretchability and wearability, and have already enabled a broad spectrum of proof-of-concept pressure sensing demonstrations in epidermal healthcare, smart textiles, soft robotics, and human–machine interfaces. ,

Despite this rapid progress, the knowledge landscape of polymer/MXene composite-based flexible pressure sensors remains fragmented across materials science, mechanics, and device engineering. Existing reviews typically focus either on MXene chemistry and general MXene-based electronics, or on flexible pressure sensors without distinguishing the unique opportunities and constraints of polymer/MXene composites. A dedicated framework that connects working mechanisms, substrate choices, structural design strategies, and application scenarios is still lacking, which hampers the rational translation of material-level advances into robust devices and systems. In this review, we therefore provide a focused and integrative overview of polymer/MXene composite-based flexible pressure sensors along four critical dimensions: (i) working mechanisms, (ii) substrate materials, (iii) structural design, and (iv) applications. We extract cross-cutting design principles, highlight persistent bottlenecks such as oxidation stability, interfacial adhesion, and manufacturing scalability, and outline future research directions toward multi-functional, durable, and system-integrated MXene pressure sensors.

Furthermore, we provide an evidence-based projection of which application verticals will reach scalable commercialization first. By evaluating the compound annual growth rate (CAGR), venture-capital (VC) inflow, regulatory barriers, and foundry-level packaging readiness, we project the following translational sequence. Firstly, industrial predictive maintenance is expected to be commercialized within 3–5 years. Although receiving slightly less media-driven VC hype compared to healthcare, the Industrial IoT sensor market exhibits a robust CAGR. More importantly, this sector faces minimal regulatory barriers (exempt from FDA/CE biocompatibility mandates) and can readily leverage mature foundry-level packaging technologies tailored for harsh, non-skin-contact environments, positioning it as the most expedient translational pathway. Secondly, epidermal health monitoring is projected to achieve commercialization within 5–8 years. This vertical attracts the highest venture-capital inflow and boasts a strong CAGR. However, scalable commercialization is currently bottlenecked by stringent medical regulatory hurdles (FDA/CE clearance) and the immaturity of packaging techniques required to simultaneously ensure breathability, washability, and long-term biocompatibility. Lastly, soft exoskeleton feedback is anticipated to reach commercialization within 7–10 years. While the robotics sector is expanding rapidly, this vertical remains a longer-term objective. It faces immense engineering challenges regarding dynamic system integration, extreme mechanical fatigue under high-strain conditions, and a critical lack of standardized foundry-level packaging for soft–rigid interfaces.

The literature search was conducted using Web of Science, Scopus, X-mol, and Google Scholar databases, covering publications from 2021 to December 2025. The search keywords included MXene, flexible pressure sensor, piezoresistive, capacitive, hybrid, and composite. The initial search yielded 650 records, with an additional 86 records identified through manual reference tracing. After removing duplicates, about 500 records were obtained. Based on title and abstract screening, 320 records that were not directly relevant to MXene-based pressure sensing were excluded. The remaining 180 full-text articles were assessed for eligibility. After excluding studies not focused on pressure sensing, those lacking quantitative data, or review articles, about 150 peer-reviewed research articles were ultimately included in this review. By mapping these technological milestones against market and regulatory realities, this review aims to serve as a consolidated knowledge base that guides both academic researchers and industry stakeholders toward the most viable and efficient pathways for practical deployment.

2. Working Mechanisms of MXene-Based Flexible Pressure Sensors

MXenes, leveraging their metallic conductivity, abundant surface functional groups, and highly tunable work function, exhibit superior performance across various sensing mechanisms compared to conventional 2D conductive materials, such as graphene and MoS₂. Flexible mechanical sensors based on MXenes can generally be categorized into four primary modalities: piezoresistive, capacitive, piezoelectric, and triboelectric (Figure ). , To obviate textual redundancy and afford readers an immediate comparative overview, the transduction principles, specific locations/roles of MXenes, comparative merits, limitations, and prospective optimization routes for each of the four sensing modalities are presented in Table .

1.

Schematic illustration of the sensing mechanisms for MXene-based flexible pressure sensors: (a) piezoresistive; (b) capacitive; (c) piezoelectric; (d) triboelectric.

1. Comprehensive Comparison of the Four Primary Sensing Modalities Utilizing MXenes.

sensing modality	piezoresistive	capacitive	piezoelectric	triboelectric
transduction principle	external force deforms the conductive network/tunneling distance/contact resistance changes	external force alters electrode spacing/effective area/dielectric permittivity	mechanical stress induces polarization change and generates charges	contact electrification coupled with electrostatic induction generates charges
MXene location/role	filler/microstructure template/interfacial layer	electrode/interfacial layer/microstructure template	electrode/filler/interfacial layer	electrode/interfacial layer
merits	simple readout circuitry/high sensitivity at low pressures/good compatibility with flexible, large-area arrays	low power consumption and good stability/designable linearity and strong repeatability/well-suited for high-resolution tactile arrays	self-generated/low-power operation/highly sensitive to dynamic stimuli/fast response and high signal-to-noise ratio	self-powered with strong output signals/ideal for event-driven sensing and human–machine interfaces/enables simultaneous sensing and energy harvesting
limitations	hysteresis and signal drift/saturation at high pressures/environmental sensitivity	parasitic capacitance and noise/strong dependence on structure and packaging/complex readout for high-resolution arrays	limited capability for static pressure sensing/high-impedance readout requirements/material and processing constraints	highly sensitive to humidity and surface contamination/difficulty in quantitative static-pressure measurement/high output impedance and more complex signal conditioning
potential optimization routes	hierarchical or interlocking microstructures to delay saturation. 1D–2D hybrid networks and stronger interfaces to improve stability. Encapsulation and temperature/humidity compensation to reduce drift	microstructured or compressible dielectrics to boost signal and linearity. Shielding, guard structures, and differential readout to suppress parasitics. Multiplexed readout and decoupling methods for large arrays	enhance piezoelectric phase and use MXene as electrode/interfacial enhancer. Strain-amplifying microstructures to increase output. Low-noise high-impedance front ends and hybridization for static–dynamic sensing	micro/nanotexturing and material-pair selection to increase charge density. Hydrophobic coatings and encapsulation for humidity robustness. Rectification, storage, and calibration/feature extraction for practical integration

2.1. Piezoresistive Type

Piezoresistive sensors function through the modulation of bulk or contact resistance mediated by tunneling currents under mechanical strain (Figure a). The total sensor resistance is primarily described by

$$\mathrm{R}={\mathrm{R}}_{\mathrm{e}}+{\mathrm{R}}_{\mathrm{f}}+{\mathrm{R}}_{\mathrm{c}}$$ 1

where R_e, R_f, and R_c denote the electrode, bulk, and contact resistances, respectively. External loading dynamically reshapes the internal conductive network. Piezoresistive MXene sensors offer advantages including structural simplicity, straightforward signal acquisition, and high sensitivity (e.g., sensitivity of 306 kPa^–1 reported in a two-electrode configuration with an active area of 1 cm² and a mass loading of ∼0.5 mg/cm²). Specifically, the decreased interlayer spacing between MXene sheets reduces the tunneling barrier, while the increased true contact area diminishes interfacial scattering. , Surface functional groups further fine-tune the piezoresistive response by modifying interfacial energy distribution. Compared with other 2D conductive materials such as graphene, which similarly rely on percolation and tunneling effects, the uniqueness of MXenes in achieving high-performance piezoresistive sensing stems from two primary factors. First, their higher intrinsic carrier density and metallic-like electronic structure render interlayer quantum tunneling effects exceptionally sensitive to minute spacing variations, thereby yielding a significantly higher gauge factor. Second, their abundant surface functional groups (−OH, –O, and –F) enable the formation of strong hydrogen bonds or chemical linkages with polymer substrates. This fundamentally suppresses interfacial slippage and contact failure during cyclic loading, ensuring superior signal linearity and long-term operational stability.

As outlined in Table , while their structural simplicity and high sensitivity make them ideal for static pressure detection (e.g., e-skin), challenges such as viscoelastic hysteresis and MXene oxidation require targeted optimization. Recently, hybridizing MXenes with highly porous covalent-organic frameworks (COFs) has emerged as a promising strategy to concurrently prevent layer restacking and enhance the chemical stability of the sensing network.

2.2. Capacitive Sensing

Capacitive sensors operate by detecting capacitance variations driven by pressure-induced changes in electrode geometry or dielectric properties (Figure b). Applied pressure induces changes in electrode area, inter-electrode distance, or the dielectric constant of the material, collectively contributing to measurable capacitance shifts. The exceptional conductivity and mechanical flexibility of MXene enable highly sensitive responses to these geometric and dielectric alterations, facilitating precise pressure detection.

Capacitance is defined as

$$\mathrm{C}=\frac{{\epsilon }_0\times {\epsilon }_{\mathrm{r}}\times A}{d}$$ 2

where ε₀ is the vacuum permittivity, ε_r is the relative dielectric constant, A represents the effective electrode area, and d denotes the inter-electrode spacing. Under mechanical compression, dimensional changes in the inter-electrode spacing or effective area modulate the capacitance. Furthermore, when MXene nanosheets are incorporated into the dielectric layer, their pronounced polarizability enhances local electric fields, improving spatial resolution. , The unique role of MXenes here lies not only in their function as high-performance flexible electrodes but also in their ability to induce a significant Maxwell–Wagner-Sillars (MWS) interfacial polarization effect when utilized as functional dielectric fillers. This stems from the substantial dielectric constant mismatch between the polar surface functional groups of MXene nanosheets and the polymer matrix, coupled with the high specific surface area interfaces they form, which collectively enhance the effective dielectric constant of the composite media more efficiently. Such a surface-chemistry-dominated dielectric enhancement mechanism is difficult to achieve with intrinsically non-polar or weakly polar carbon materials, such as graphene. As summarized in Table , capacitive sensors boast minimal power consumption and low hysteresis, making them suitable for long-term wearable monitoring. However, their susceptibility to environmental interference and relatively weak output signals necessitate careful structural design, such as introducing microstructured dielectrics.

2.3. Piezoelectric Sensing

Piezoelectric sensors utilize materials that generate transient electrical polarization under mechanical stress due to asymmetric charge distribution (Figure c). MXenes exhibit intrinsic piezoelectricity originating from their non-centrosymmetric crystal structure, where elastic deformation induces lattice distortion. , In practical devices, MXene is frequently composited with piezoelectric polymers (e.g., PVDF) to strengthen electromechanical coupling. The induced piezoelectric potential drives current flow by modulating Schottky barriers and disrupting the Fermi-level equilibrium. Specifically, the electronegative functional groups on the MXene surface act as nucleating agents, inducing the phase transition of the polymer from a non-polar α-phase to a polar β-phase via electrostatic interactions. Furthermore, the high electrical conductivity of MXenes facilitates the formation of Schottky contacts at the interface. By modulating the interfacial barrier height through applied pressure, the collection efficiency of piezoelectric charges is further enhanced. As detailed in Table , their self-powered nature and rapid dynamic response are highly advantageous for vibration and impact monitoring. Nevertheless, inherent charge leakage restricts their ability to measure static pressure, requiring specific interface engineering to maximize performance.

2.4. Triboelectric Sensing

Triboelectric sensors operate through the coupled mechanisms of contact electrification and electrostatic induction (Figure d). Mechanical stimuli induce interfacial charge transfer, which is subsequently converted into measurable signals. MXene’s high electron affinity and polar terminal groups significantly enhance charge trapping capacity, while its excellent electrical conductivity improves charge transport efficiency. The core advantage of MXenes in the triboelectric mechanism stems from their extremely high intrinsic electronegativity, which is dictated by the enrichment of strongly electronegative –F and –O surface terminations. This places them at an extreme position in the triboelectric series, making them highly efficient electron-trapping materials. Furthermore, the inherently excellent electrical conductivity of MXenes enables them to simultaneously serve as efficient charge collection and storage layers. This overcomes the drawback of easy charge dissipation found in traditional insulating triboelectric materials, thereby enhancing both output performance and stability. , Constructing multilayer architectures and increasing surface roughness further amplify the output power. As systematically compared in Table , triboelectric sensors offer exceptional design flexibility and energy-harvesting capabilities. To realize fully independent self-powered sensing systems, these triboelectric units are frequently integrated with high-performance supercapacitors. In order to deeply unravel the complex charge storage mechanisms, ion dynamics, and interfacial behaviors within these integrated energy devices under real working conditions, advanced in situ and operando characterization techniques (e.g., real-time X-ray, NMR, and scanning probe methods) have become indispensable tools. , Leveraging these sophisticated techniques provides vital insights for optimizing the structural integrity and efficiency of next-generation MXene-based energy-sensing systems. , However, their performance is highly sensitive to environmental humidity, highlighting the necessity for robust encapsulation and surface chemical tuning in future developments.

In summary, the four sensing mechanisms employ distinct signal transduction pathways: geometric modulation of electron transport (piezoresistive), dielectric parameter coupling (capacitive), crystal dipole variation (piezoelectric), and interfacial charge transfer (triboelectric). Piezoresistive and capacitive types suit static measurements, while piezoelectric and triboelectric types excel in dynamic response. Piezoresistive and triboelectric sensors achieve high sensitivity, whereas capacitive and piezoelectric types offer advantages in power efficiency. MXene’s high conductivity, two-dimensional structure, and tunable surface chemistry provide synergistic enhancement across these mechanisms through improved tunneling probability, enhanced polarization effects, and optimized field distributions. Future developments should focus on transcending single-mechanism limitations through coordinated material and structural design that activates multiple mechanisms simultaneously, enabling multi-modal, highly sensitive, and self-powered flexible pressure sensing platforms.

3. Substrate Materials for MXene-Based Flexible Pressure Sensors

3.1. Cellulose Paper Substrates

Cellulose paper serves as an advantageous substrate for flexible piezoresistive sensors, offering distinctive benefits including facile processability, high flexibility, breathability, and skin compatibility, thereby aligning with the requirements for sustainable electronics. Its inherent structural characteristics make it particularly suitable for flexible sensing applications. A typical fabrication approach involves screen-printing interdigital electrodes (IDEs) onto cellulose paper, followed by uniform MXene deposition via dip-coating to create a cellulose/MXene composite sensing layer, ultimately encapsulated with an additional paper layer to form a fully cellulose-based sandwich structure. For simplified manufacturing, direct printing of MXene ink onto paper substrates produces uniform conductive layers that penetrate into the fiber pores. The sensor exhibits a four-segment linear response across different pressure ranges, with a pressure sensitivity of of 13.408 kPa^–1 and 3.8961 kPa^–1 in the low-pressure region, and 0.1363 kPa^–1 and 0.011 kPa^–1 in the high-pressure region. It has a pressure detection range of up to 1200 kPa and maintains stable signals even after 1050 loading–unloading cycles under 2 N conditions, demonstrating excellent cyclic stability. By utilizing a 5 mg mL^–1 MXene dispersion as the ink in an HP printer, this technique achieves a denser MXene distribution and more continuous conductive networks compared to conventional dip-coating. Consequently, it yields sensors with high sensitivity, a broad pressure detection range, and exceptional cycling stability (Figure a). Nevertheless, conventional integration methods like immersion and ink printing remain inadequate for multi-scenario applications, with sensitivity enhancement constituting a key research focus. Innovative molecular bridging strategies and paper structural designs have emerged to address these limitations. Functioning as both dispersants and interfacial enhancers, they provide optimal adsorption sites for conductive fillers and strengthen interfacial bonding (Figure b). During fabrication, the functionalized cellulose paper substrate was subjected to four consecutive dipping–drying cycles in the ink. This specific parameter enables the conductive fillers to uniformly adsorb onto the paper and form a highly stable conductive layer. Ultimately, utilizing the synergistic combination of MXene’s temperature sensitivity and graphene’s mechanical reinforcement within this stable network enables simultaneous pressure–temperature dual-mode detection. Under high-humidity conditions or exposure to sweat, the abundant hydroxyl groups on paper cellulose readily adsorb water molecules, causing rapid mechanical deterioration and consequent sensing performance degradation. Conventional protection strategies employ elastic substrate encapsulation to isolate paper sensors from moisture, ensuring long-term operational stability in aqueous environments (Figure c). To address the application demands of wearable pressure sensors in realistic wet environments, pressure-sensing performance tests were conducted under high-humidity and underwater conditions. These tests were designed to emulate typical failure scenarios for conventional paper-based sensors, including exposure to sweat, humid weather, and shallow-water settings (e.g., bathing and swimming), thereby verifying the operational stability of the proposed smart wearable pressure sensor in water-containing environments. For the high-humidity evaluation, the device was placed in a controlled atmosphere with a relative humidity of 38–100% RH and subjected to cyclic loading tests under a constant bias (operating voltage: 0.1 V). In addition, the sensor was worn on the human wrist for dynamic monitoring. More recently, chemical vapor deposition (CVD) has been utilized to create robust hydrophobic coatings that enhance humidity resistance while preserving the porous and breathable structure of cellulose paper. Specifically, using methyltrichlorosilane as the precursor, the vapor deposition is carried out at 50 °C in a vacuum environment for 5 min. This precisely controlled process enables sufficient reaction with the hydroxyl groups on the cellulose fibers, introducing Si–C, Si–O–Si, and Si–O–C bonds to achieve a successful hydrophilic-to-hydrophobic transition. Consequently, this modification significantly improves sensor performance and stability in high-humidity applications (Figure d).

2.

MXene-cellulose/paper-based flexible pressure sensors. (a) Fabrication process of the MXene printed paper (MPP)/MXene printed interdigitated electrode (MPIE) all-cellulose-based flexible pressure sensor. Reproduced with permission from ref . Copyright 2023 American Chemical Society. (b) Fabrication process of the graphene/MXene/cellulose paper-based flexible dual-mode sensor. Reproduced with permission from ref . Copyright 2024 Elsevier B.V. (c) Fabrication process of the all-paper flexible piezoresistive sensing system. Reproduced with permission from ref . Copyright 2023 Springer Nature. (d) Fabrication process of the fully paper-based, flexible, and biodegradable pressure sensor. Reproduced with permission from ref . Copyright 2024 Wiley-VCH Verlag.

The core value of MXene paper-based sensors lies in their ultra-low cost, excellent breathability, and eco-friendliness, endowing them with irreplaceable advantages in disposable, wearable, or large-area distributed low-cost sensing applications (e.g., smart packaging and temporary physiological monitoring patches). However, current challenges for MXene paper-based sensors primarily include limited oxidation stability, high moisture sensitivity, insufficient mechanical strength, and complex manufacturing processes. This restricts its application in environments that require long-term reliability or involve complex mechanical conditions. Future investigations should concentrate on enhancing MXene stability and dispersion through surface modification and composite design, while simultaneously optimizing paper substrate properties to improve overall sensor performance. The development of simplified manufacturing protocols and environmental synthesis methods represents a crucial step toward commercial implementation. Through multidisciplinary approaches enabling multifunctional integration, these sensors hold significant potential for expansion into wearable electronics and smart e-skin applications.

3.2. Textile Materials

3.2.1. Textile Fiber-Based Substrates

Textile fiber substrates have become a vital platform for developing flexible MXene-based pressure sensors, combining flexibility, breathability, and mechanical durability which are key properties for wearable and smart textile applications. These substrates capitalize on the inherent advantages of textile fibers, such as lightweight construction, high porosity, and conformability, to reconcile mechanical integrity with effective thermal and moisture management. A representative design presents a variable-density point-type pressure sensing array (PSA) based on core–sheath yarns, utilizing a conductive stainless-steel core and a flexible, breathable polyester sheath. To facilitate uniform MXene deposition, the polyester surface is functionalized with oxygen-containing polar groups via oxygen plasma treatment (200 W, 40 sccm, 10 min) to enhance hydrophilicity. Relying on a piezoresistive mechanism driven by variable inter-fiber contacts, the sensor exhibits fast response/recovery times of ∼80 ms and an ultra-broad detection range from 7.2 Pa to 15,000 kPa. Spatial pressure-mapping was evaluated using a 2 × 3 woven array (pixel area ∼0.5 cm²); under a 50 kPa single-point load, the pressed pixel yielded a massive relative current change (ΔI/I ₀) of 46.51–49.98, while adjacent pixels showed negligible crosstalk of only 0.05–0.4 (<0.8% of the primary signal), demonstrating excellent electrical isolation. Furthermore, the device exhibited outstanding durability, maintaining stable output over 10,000 loading/unloading cycles at 2000 kPa and retaining 81.25% of its response across 20–60 °C (Figure a). However, conventional coating methods that rely solely on the physical adsorption of MXene on the fiber surface result in a thin conductive layer prone to detachment, enabling only single-mode pressure sensing and failing to meet the requirements for dual-modal sensing. In contrast, the dual-modal sensor, constructed synergistically with an MXene/AgNW composite conductive network and a porous hydrogel scaffold (MACHy), embeds the conductive layer within a three-dimensional framework, thereby enhancing the structural stability and fatigue resistance of the conductive network. Additionally, the hydrogel coating provides antioxidative protection for MXene, addressing the wet-state failure issue commonly observed in coated MXene sensors (Figure b). The performance of the MCC pressure sensor was evaluated using an IM3536 LCR digital bridge. The prepared MCC fibers (2 cm in length) were connected to wires at both ends and attached to electrodes using conductive silver paste to form the pressure sensor. During testing, the frequency was set to 100 kHz and the test voltage was 1 V. The pressure sensing experiments included real-time current response measurements (I-T curves), I–V curves under different pressures, response and recovery time measurements, sensitivity evaluation, and cyclic stability tests. For the cyclic stability test, the sensor was connected to the LCR digital bridge and placed under a mechanical testing machine. The sensor was subjected to 4000 compression cycles under a load of 6.66 kPa, and the resistance variations were recorded. For sensitivity measurements, the mechanical testing machine was set to a pressure loading range of 0–300 kPa, and the resistance data from the LCR bridge were recorded simultaneously with the mechanical loading data. Furthermore, researchers have proposed a coaxial wet-spinning technique to fabricate core–sheath structured MXene/cellulose nanofibers (CNFs)@cationic cellulose aerogel fibers, which achieve piezoresistive sensing while simultaneously incorporating a humidity sensing mode, demonstrating the multi-modal perception capabilities of fiber-based sensors. This method integrates both sensing modalities within a single fiber, allowing decoupled monitoring of pressure and humidity. Moreover, the synergistic interaction between MXene nanosheets and CNFs yields a three-dimensional porous architecture with linear-to-areal support, substantially boosting sensing performance (Figure c). The synergy between fabrication strategy and structural design is critical to enhancing sensor performance. For instance, Wei et al. developed an MXene/nanocellulose/carbon sphere composite film (ACMF) with an “egg-box” morphology. Here, nanocellulose nanofibers serve as the flexible structural scaffold, offering mechanical reinforcement, conformability, and porosity, while interweaving closely with MXene nanosheets to form an entangled 3D network (Figure d). Such advances continuously improve the sensitivity and response speed of MXene-based sensors.

3.

MXene-based textile fiber flexible pressure sensors. (a) Fabrication process of the all-textile flexible pressure sensor. Reproduced with permission from ref . Copyright 2023 Elsevier B.V. (b) Preparation procedure of the MACHy dual-mode sensor. Reproduced with permission from ref . Copyright 2025 Wiley-VCH Verlag. (c) Preparation process of the MXene/CNF@cationic cellulose aerogel fibers. Reproduced with permission from ref . Copyright 2025 Royal Society of Chemistry. (d) Fabrication process of the multi-level “egg-crate” structured MXene/nanocellulose nanofiber/carbon sphere composite film. Reproduced with permission from ref . Copyright 2025 Royal Society of Chemistry. (e) Preparation and applications of the flexible piezoresistive sensor based on a porous PVDF/CNC/MXene film. Reproduced with permission from ref . Copyright 2025 Elsevier B.V.

Nevertheless, balancing thermal-wet comfort with mechanical strength remains essential for expanding their wearable applicability. Ding et al. employed electrospinning-under optimized parameters including an applied voltage of 12–15 kV, a flow rate of 1 mL/h, a collection distance of 14 cm, and a collector rotation speed of 100 rpm, to successfully fabricate a porous poly­(vinylidene fluoride)/cellulose nanocrystal/MXene (PVDF/CNC/MXene) film that combines high breathability with excellent mechanical properties (Figure e). This approach alleviates the typical trade-off between flexibility and air permeability in conventional sensors, improves durability, and offers valuable design principles for future polymer/MXene composite materials. By optimizing both materials and structures, researchers are addressing issues of stability and production costs, thereby advancing overall sensor performance and enabling more stable, adaptive, and multifunctional sensing systems. Distinct from macroscopic planar paper-based or monolithic fabric substrates, the unique advantage of single functionalized fibers lies in their microscopic discreteness and independent controllability, serving as individual sensing pixels. This characteristic enables the integration of multi-field coupled sensing (e.g., decoupled monitoring of pressure and humidity) at the single-fiber scale through coaxial spinning or core–shell structural design, thereby achieving high-spatial-resolution mapping of local stress distributions or microenvironmental changes. Furthermore, this line-to-plane fabrication paradigm not only provides smart textiles with excellent structural conformability and design flexibility, but also demonstrates superior sensing precision compared to macroscopic substrates in scenarios demanding high accuracy, such as precision medical monitoring (e.g., capturing subtle pulse waves) and fine motion recognition. However, their application boundaries are primarily restricted by the elimination of signal crosstalk within complex textile structures, the consistency control of functional units during large-scale manufacturing, and the integration complexity of signal extraction circuits. Future research should focus on further enhancing their long-term cyclic stability and environmental durability through interface engineering while maintaining the intrinsic mechanical strength of the fibers. This remains a crucial step in driving fiber-based sensors from laboratory-scale research toward the industrialization of all-weather, multifunctional smart wearable systems.

Textile fiber substrates, with their intrinsic three-dimensional network, flexibility, and permeability, offer a promising foundation for next-generation high-performance wearable pressure sensors. Current research focuses on actively designing and tuning conductive pathways and porous interfaces through advanced spinning technologies and tailored microstructures. The evolution from simply using substrates to proactively designing and functionalizing them represents a fundamental shift. This transformation is the central driving force behind the dramatic, leapfrog improvements in sensor performance parameters like sensitivity, response range, and stability. Future efforts should prioritize multifunctional integration with signal decoupling. The incorporation of pressure, temperature, humidity, and strain sensing within individual fibers or textiles is a logical direction for smart textiles. A major challenge is developing advanced material systems such as MXene hybrids with other functional materials and innovative structures that enable accurate discrimination between different physical stimuli, ensuring reliable and precise signal output. Equally important is shifting the focus from performance metrics to practical viability. Beyond high sensitivity and fast response, long-term operational stability under real-world wearing conditions must be addressed. Key issues include preventing MXene oxidation in ambient conditions, maintaining performance after repeated washing and mechanical deformation, and minimizing interference from sweat or temperature variations.

Looking forward, textile-based sensors should evolve from standalone components into integrated input modules within broader functional systems. The incorporation of sensing fibers with energy storage units, energy harvesters, and logic circuits via textile-compatible integration will pave the way for truly “smart” fabrics capable of real-time sensing, analysis, and response. Such progress will solidify the role of MXene-based fiber sensors in personalized health monitoring, human–machine interfaces, and advanced protective gear.

3.2.2. Fabric-Based Substrates

The integration of MXene with textile fabrics enables the development of high-performance fabric-based sensors. By employing interface modification, composite formation, and coating techniques, researchers have improved both the dispersion stability of MXene and the sensitivity of the resulting sensors. These systems combine the intrinsic electrical conductivity of MXene with the flexibility, breathability, and comfort of textiles, meeting key requirements for wearable applications. , For example, a composite knitted fabric incorporating MXene with chitosan (CS) and polydopamine (PDA) has been developed. The CS-PDA@MXene architecture not only improves the dispersion of MXene, but also enhances the sensing sensitivity and broadens the pressure-detection range, particularly in the low-pressure region. In performance evaluation, pressure was applied using a push–pull force gauge and/or a tensile testing setup, and the electrical signals were recorded with a Keithley 2450 source meter. The sensor exhibited a wide operating range of 0–552.8 kPa, achieving the highest sensitivity of 15.135 kPa^–1 in the low-pressure range of 0–33 kPa, followed by sensitivities of 6.05 kPa^–1 and 2.969 kPa^–1 in the 33–173.5 kPa and 173.5–552.8 kPa ranges, respectively, demonstrating compatibility in detecting both slight touch and relatively high loads. Notably, the sensor maintains a stable current output even in underwater environments. Advancing this approach, Gu et al. utilized electrophoretic deposition to uniformly assemble MXene nanosheets onto fibers. Specifically, the deposition was carried out at a direct current (DC) voltage of 5 V for an optimized duration of 1 h, followed by drying at 60 °C for 30 min. This precisely controlled fabrication yielded a robust CS/MXene-based textile sensor capable of real-time motion monitoring. When integrated with a deep neural network, the system achieves accurate classification of six common human activities. While coating and electrophoretic deposition improve MXene adhesion and dispersion, long-term mechanical durability especially under cyclic bending or stretching remains challenging. To address this, Wang et al. developed a polydimethylsiloxane (PDMS)/silver nanowires (AgNWs)/MXene fabric via nanoscale penetration and interface optimization. This design enhances electrical stability and introduces multifunctionality, including pressure sensing, electrothermal response, and electromagnetic interference (EMI) shielding. Further extending this concept, Merga et al. constructed a multi-scale hybrid material incorporating MXene, GO, and AgNWs, which synergistically improves electrical conductivity, electrothermal efficiency, and EMI shielding performance. To mitigate MXene’s susceptibility to oxidation and moisture-induced degradation, surface functionalization strategies offer promising solutions. Zhang et al. applied a perfluorooctyltriethoxysilane (PFOTES) coating to enhance MXene’s antioxidant and hydrophobic properties, thereby significantly improving both its stability and electrothermal conversion efficiency. Compared to paper-based and individual fiber substrates, fabric-based sensors utilize textiles directly as structural carriers, enabling their seamless transformation into comfortable, breathable, and highly wearable functional garments. Consequently, they are well-suited for the continuous monitoring of large-scale, macroscopic human activities (e.g., joint movements and posture recognition), possessing distinct advantages in terms of wearability and user acceptance. However, the uniformity and reliability of their sensing performance are highly contingent upon the complete and robust decoration of MXene across the entire fabric surface. MXene-based fabric sensors still face persistent challenges regarding insufficient interfacial stability, susceptibility to oxidation, and performance degradation stemming from their intrinsic hydrophilicity. These issues become particularly pronounced under cyclic stretching conditions. To address the challenges of vulnerability to environmental factors and weak interfacial adhesion, strategies including surface functionalization, hybrid material design, and micro-dissolution processes exhibit broad implementation prospects. Through the continuous optimization of material properties, enhancement of stability, and reduction of production costs, MXene-based fabric sensors are poised to demonstrate immense application potential in fields such as smart health monitoring, environmentally adaptive sensing, and next-generation wearable devices.

The field has progressed from simple physical coating toward sophisticated interfacial engineering and multi-material integration, enabling simultaneous optimization of conductivity, sensitivity, and auxiliary functions such as electrothermal heating and EMI shielding. However, the practical deployment of MXene-based fabric sensors remains constrained by oxidative instability, interfacial adhesion limitations, and performance degradation under cyclic stress. Future efforts should prioritize practical reliability and system-level integration. Developing robust encapsulation strategies and stable multi-material architectures will be essential to ensure operational durability in real-world environments. In parallel, scalable fabrication routes compatible with industrial textile processes must be established. Ultimately, integrating sensing, energy, and computation within a single textile platform will pave the way for intelligent systems suited to personalized health monitoring and advanced human–computer interaction.

While all three substrate categories offer unique benefits for MXene integration, their selection is governed by specific application boundaries. Paper-based substrates are unparalleled for low-cost, disposable, and eco-friendly applications, though their performance may degrade in high-humidity environments. Fiber-based sensors excel in micro-scale sensing and detecting localized, subtle physiological signals due to their ultra-high flexibility and minimal mechanical impedance. In contrast, fabric-based substrates remain the gold standard for large-area, breathable wearable patches that require superior conformability, long-term stability, and washability. This horizontal differentiation ensures that the structural design of MXene-based sensors can be precisely tailored to the mechanical and environmental demands of the target application. A comprehensive horizontal comparison of the three wearable substrate categories including paper, fiber, and fabric is presented in Table , highlighting their irreplaceable advantages, applicable boundaries, and typical deployment scenarios.

2. Horizontal Comparison of Paper, Fiber, and Fabric Substrates for MXene-Based Sensors.

substrate type	irreplaceable advantages	applicable boundaries	typical scenarios
paper-based	low cost, biodegradable, high capillary effect for ink loading, recyclable	sensitive to humidity; limited mechanical durability under repeated large strains	disposable electronics, point-of-care diagnostics, eco-friendly sensors
fiber-based	ultra-high flexibility, suitable for micro-scale sensing, excellent 1D integration	lower absolute signal output due to small area; complex large-scale assembly	subtle physiological signals (pulse, eye blink), smart sutures, e-textile components
fabric-based	high breathability, superior comfort/conformability, excellent washing durability	surface roughness can affect coating uniformity; lower patterning resolution	long-term healthcare monitoring, sports tracking, smart garments

This comprehensive schematic (Figure ) provides a multi-dimensional assessment of MXene-based textile sensors, charting their trajectory from laboratory development to commercialization. Initially, Figure a illustrates the structural evolution from basic single-layer coatings to multi-scale composites (e.g., incorporating Graphene Oxide) and surface functionalization (e.g., PFOTES hydrophobic coatings). This progression has endowed textiles with superior conductivity, multifunctionality such as EMI shielding and Joule heating, and smart recognition capabilities. As a direct result of these material optimizations, the radar chart of Figure c reveals that MXene textiles boast an absolute advantage over traditional FDA/CE-cleared commercial flexible sensors regarding Sensitivity and Limit of Detection. However, the technology readiness level (TRL) distribution in Figure b indicates that while industrial/environmental sensing is approaching TRL 6, core applications like epidermal health monitoring and smart gesture recognition remain predominantly confined to the prototype validation stage (TRL 4–5). The primary bottleneck preventing their transition to full commercialization (TRL 7–9) is glaringly highlighted in Figure c that is an inferior operational lifetime. Corroborating this, the technology roadmap in Figure d explicitly identifies that while substantial success has been achieved in material-level optimization, the susceptibility to oxidation, weak interfacial adhesion under cyclic stress, and fatigue degradation constitute the critical gap bridging the current status and future system integration. Future research must, therefore, prioritize robust encapsulation and washability to ultimately realize scalable manufacturing and hardware-software system integration.

4.

Data-centric roadmap, performance benchmarking, and translational gap analysis of MXene-based textile sensors. (a) Schematic summary of the structural evolution and multifunctional integration of MXene textiles, progressing from initial interface modification (e.g., CS/PDA) to multi-scale compositing and protective surface functionalization. (b) Technology Readiness Level (TRL) distribution across key application sectors, highlighting the current transition from lab-scale concepts to prototype validation in relevant environments. (c) Radar chart benchmarking the typical performance of MXene textile sensors against FDA/CE-cleared commercial flexible sensors in terms of sensitivity, limit of detection, and operational lifetime. (d) Critical gap analysis and technology roadmap illustrating the technological milestones from achieved material optimization to future system integration, with the major translational chasm currently residing in long-term device reliability under cyclic stress.

3.3. Foam-Based Substrates

Foam materials, with their intrinsic porous architectures, offer an ideal platform for developing high-performance flexible pressure sensors. The interconnected pore structure not only facilitates efficient stress distribution but also enhances strain concentration under loading, contributing to high sensitivity and fast response in detecting subtle pressure variations. Recent advances in MXene-based foam sensors have focused on improving their sensitivity, durability, and multifunctionality through innovative manufacturing techniques and strategic material integration. A notable development in multifunctional sensing is the design of composite foams incorporating thermoplastic polyurethane, epoxy resin, carbon nanotubes (CNTs), dopamine, and MXene. These systems demonstrate remarkable electromagnetic interference shielding and impact resistance (sensor with two-electrode configuration, active area: 1.5 cm², MXene loading: ∼0.8 mg/cm²). Further expanding their applicability, a 3D porous shear-stiffening elastomer (SSE)/MXene foam has been developed to simultaneously provide flexibility, breathability, and antibacterial properties. A real-time resistance acquisition scheme was employed: during the application of mechanical stimuli, the resistance changes were synchronously recorded using a Modu-Lab MTS measurement system, with conductive copper tape serving as electrodes to ensure stable electrical contact. This established a coupled characterization framework linking pressure/impact loads to electrical responses. Furthermore, leveraging MXene’s photothermal effect, this foam enables effective bacterial elimination under laser irradiation, showing great potential for medical and hygiene-sensitive applications (Figure a).

5.

MXene-based foam flexible pressure sensors. (a) Fabrication process of the three-dimensional porous elastomer (SSE)/MXene (M-SSE) foam. Reproduced with permission from ref . Copyright 2023 Springer Nature/Tsinghua University Press. (b) Design and preparation of the MXene/CNTs-coated silicone foam pressure sensor. Reproduced with permission from ref . Copyright 2024 Wiley-VCH Verlag. (c) Manufacturing workflow of the MIPS flexible pressure sensor. Reproduced with permission from ref . Copyright 2024 Wiley-VCH Verlag. (d) Preparation process of the polyurethane/porous carbon nanosheet foam-based piezoresistive sensor. Reproduced with permission from ref . Copyright 2024 American Chemical Society. (e) Design and fabrication of the CS/polyurethane/MXene flexible pressure sensor. Reproduced with permission from ref . Copyright 2025 American Chemical Society.

Despite these advances, maintaining reliable performance under extreme conditions remains challenging. To address this challenge, researchers have explored a series of targeted technical strategies tailored to enhance the environmental adaptability and structural stability of MXene-based foam sensors, including the development of MXene/CNTs-coated silicone foam for wide-temperature operation, MXene-decorated melamine foam integrated with ion-conductive layers for improved interfacial adhesion, microwave sintering technology for uniform MXene infiltration and material integrity, as well as bioinspired structural designs for optimized stress distribution and sensing performance, all of which are detailed in the subsequent sections. Chen et al. addressed this by developing a silicone foam coated with MXene/CNTs nanocomposites. The resulting sensor maintains excellent flexibility across a wide temperature range (−60 °C to 210 °C) and exhibits high sensitivity under 0–70% compressive strain (Figure b). Process innovation has played a crucial role in enhancing interfacial properties and overall performance. Cetin et al. introduced an ion-conductive process where MXene-coated melamine foam is combined with an electrolyte to form a continuous ion-conductive layer. Specifically, the electrolyte was prepared by dissolving thermoplastic polyurethane (TPU) in N,N-dimethylformamide (DMF) at a 1:20 mass ratio under vigorous stirring for 24 h, followed by the addition of 1-ethyl-3-methylimidazolium bis­(trifluoromethylsulfonyl)­imide (EMIM-TFSI) at a 0.8:1 mass ratio relative to TPU and another 24 h of stirring to ensure homogeneity. This precisely formulated approach significantly improves interfacial adhesion, leading to enhanced sensitivity, stability, and durability in flexible pressure sensors (Figure c). The MXene-deposited melamine foam-based iontronic pressure sensors (MIPS) serve as an ideal porous scaffold, while the ion layer facilitates efficient charge transport and minimizes delamination risks. Meanwhile, as an efficient alternative to conventional methods, microwave sintering prevents material degradation through rapid thermal effects while leveraging foam porosity to achieve uniform infiltration, thereby enhancing interfacial homogeneity. Zhang et al. utilized this technique to integrate MXene conductive layers with polyester (PU) foam, achieving uniform coating penetration and strong interfacial adhesion. The rapid thermal processing prevents material degradation while ensuring consistent electrical conductivity throughout the porous network (Figure d). Beyond material and process optimization, biomimetic structural design offers another dimension for performance enhancement. Inspired by the intermuscular bone structure of freshwater fish, a 3D-printed needle-like pillar array has been integrated with a MXene foam substrate. This bioinspired architecture effectively distributes stress through its porous network, enabling linear response over a broad pressure range (0–550 kPa) with a maximum sensitivity of 428.94 kPa^–1 (two-electrode configuration, active area: 0.5 cm², MXene loading: ∼0.3 mg/cm²) (Figure e).

Current research on MXene foam-based flexible sensors demonstrates a clear trend from single-mode pressure detection toward multifunctional integration including EMI shielding, antibacterial activity, and wide-temperature operation. Through multi-material hybridization, advanced manufacturing processes, and bioinspired structural design, researchers have significantly improved the sensitivity, sensing range, and environmental durability of these sensors. Nevertheless, challenges remain in interfacial adhesion, long-term cycling stability, and the complexity of fabrication processes that hinder scalable production. Future work should focus on developing novel interfacial engineering strategies such as chemical bonding or physical interlocking to enhance stability under extreme conditions. Exploring low-cost, high-throughput manufacturing techniques compatible with industrial standards will be essential to promote practical adoption. Furthermore, co-design of multiple physical functionalities should be pursued to maintain high sensitivity while broadening the sensing range. Integrating sensing with energy harvesting and storage will also be key to advancing next-generation smart wearables and human-machine interfaces.

3.4. Aerogel-Based Substrates

As a two-dimensional metallic conductor, MXene exhibits excellent carrier mobility and tunable interlayer spacing. However, its strong hydrophilicity and limited self-assembly capability pose significant challenges in constructing stable three-dimensional porous networks, particularly for scalable production. To address these limitations, recent research has increasingly focused on developing scalable and designable 3D conductive networks that balance high sensitivity, broad detection range, and long-term stability. Aerogels, known for their high porosity and low density, serve as ideal substrates for achieving exceptional sensitivity and rapid response times in pressure sensors. To mitigate structural collapse induced by capillary forces during natural drying, laser-engraved spherical graphene-MXene aerogels (SGMAs) have been developed. Specifically, the fabrication employed an ultraviolet laser etching machine operating at an etching speed of 1000 mm s^–1, a current of 10 A, a frequency of 10 kHz, and a Q pulse width of 10 μs. This approach simultaneously ensures structural integrity and continuous conductive pathways, resulting in sensors with a low detection limit of 4 × 10^–4 kPa (two-electrode configuration, active area: 1 cm², MXene mass loading: ∼0.6 mg/cm²) and excellent cyclic stability with 99% strain retention after 1000 cycles at 40% strain, and durable performance over 10,000 loading cycles (Figure a). Alternative fabrication strategies include utilizing Pickering emulsion templates with PDMS as the matrix and MXene as the conductive filler. In this approach, sodium carboxymethyl cellulose (CMC) is employed to modify MXene, effectively addressing the interfacial compatibility between the two components. Specifically, the process utilizes a Pickering emulsion with a water-to-oil volume ratio of 4:1 and an MXene-to-CMC mass ratio of 2:1. Through unidirectional freeze-casting (freezing at −18 °C for at least 4 h) followed by freeze-drying and thermal curing (150 °C for 30 min), robust PDMS/CMC-MXene (PCM) composite aerogels are formed. By further regulating the mass ratio of PDMS to MXene at 16.5:1, the optimal sensing substrate (PCM-3) is achieved, where PDMS chains bond in situ on the MXene nanosheets to create a stable and sensitive piezoresistive network. Significant progress has also been made in programmable structures. Xu et al. employed ice-templating and freeze-drying to fabricate CNFs/MXene composite aerogels with accordion-like hierarchical architectures. To ensure optimal interfacial compatibility, CNFs were chemically modified using a NaOH/urea reagent (2.1:3.6 mass ratio, 28.5% total concentration), while MXene nanosheets were prepared via etching at 45 °C for 24 h followed by 2 h of ice-bath ultrasonication. By combining these components in a mixed solution (0.8 mg/mL CNF and 2 mg/mL MXene) and applying specific thermal treatments-freezing at −80 °C for 12 h followed by 3 days of freeze-drying-the CNFs and MXene nanosheets self-assemble into ordered layered structures. This precise control over fabrication enables piezoresistive sensors with a gauge factor of 3.13 and outstanding fatigue resistance, suitable for real-time human motion monitoring (Figure d).

6.

MXene-based aerogel flexible pressure sensors. (a) Preparation process and surface morphology of the SGMA flexible mechanical sensor. Reproduced with permission from ref . Copyright 2024 Wiley-VCH Verlag. (b) Fabrication procedure of the MXene/PI/AgNWs composite aerogel. Reproduced with permission from ref . Copyright 2023 American Chemical Society. (c) Manufacturing process of the MXene/bacterial cellulose flexible pressure sensor. Reproduced with permission from ref . Copyright 2024 Springer Nature. (d) Preparation workflow and surface morphology of the CNFs/MXene composite aerogel pressure sensor. Reproduced with permission from ref . Copyright 2023 American Chemical Society.

Addressing the trade-off between conductivity and mechanical performance remains challenging. Pure MXene aerogels often suffer from sparse junctions and fragile nodes, leading to structural failure under cyclic compression. Strategies incorporating flexible polymer bridges, metal nanowires, or nanoparticles have been developed to enhance both mechanical robustness and electrical continuity. For instance, Xu et al. introduced polyimide (PI) bridges and AgNWs through bidirectional freezing and annealing, creating lightweight yet tough aerogel structures (Figure b). Beyond conventional material optimization, innovative designs such as silane-modified MXene/oxidized bacterial cellulose composites have yielded hydrophobic aerogels with improved compression resistance and recovery. These maintain high stability and piezoresistive performance even under repeated compression and deformation (Figure c).

Innovations in materials and composite design have further enhanced the sensitivity and mechanical strength of aerogels, while also addressing the issue of performance retention under high strain. However, key challenges remain for MXene aerogel sensors. While the insufficient stability of aerogels under compression or cyclic strain caused by weak interlayer bonding can be partially mitigated by introducing reinforcements or modifications, this challenge is not yet fully resolved. Parallel to this, the design of composite aerogels, which integrate materials with diverse properties, requires in-depth study to achieve effective synergy and maximize the performance of each component. Furthermore, existing techniques such as natural drying and rapid processing face a critical limitation. They cannot guarantee consistent material performance within the constraints of large-scale, low-cost production, highlighting the pressing need to overcome mass production and sustainability hurdles.

Future development of MXene aerogel sensors should prioritize multi-functional integration through advanced material design and functionalization. This includes creating composite systems that combine sensing with energy storage and thermal management capabilities, thereby expanding their applications in smart wearable devices, artificial e-skin, and flexible electronics. Concurrently, emphasis should be placed on developing environmentally friendly and cost-effective mass production techniques, such as natural drying and low-temperature processing technologies, to meet industrial requirements for scalability and economic viability. A balanced approach integrating performance optimization with sustainable development is crucial. This involves continuous improvement in materials and structures to enhance sensitivity, stability, response speed, and fatigue resistance, while simultaneously addressing environmental concerns through reduced pollution in MXene production, improved material degradability, and exploration of green synthesis pathways.

3.5. Hydrogel-Based Substrates

Hydrogel materials, characterized by high water content and excellent biocompatibility, provide an ideal matrix for developing flexible sensors. The integration of MXene with hydrogels can be achieved through in situ polymerization or blending methods. The inherent hydration of hydrogels enhances flexibility and wearing comfort, while the incorporation of MXene improves electrical conductivity and mechanical properties, making the resulting composites particularly suitable for monitoring physiological signals such as pulse and respiration. , Despite their significant potential in flexible electronics, MXene-incorporated hydrogels face several challenges, including oxidation stability, mechanical strength, temperature adaptability, and multifunctional integration. The susceptibility of MXene to oxidative degradation in ambient conditions often leads to deteriorated electrical and mechanical performance. To address this, an integrated strategy utilizing MXene to simultaneously promote rapid gelation and phase-separation foaming has been developed. This approach enables the fabrication of polyacrylamide (PAM)/ CS/MXene hydrogels, shifting the conventional focus from merely increasing surface area to synergistically regulating interface properties and ion transport dynamics. Specifically, tuning the MXene content effectively modulates hydrogen bonding interactions and surface resistance, enabling precise control over material properties.

Despite these advances, oxidation remains a critical issue affecting long-term stability. Liquid metal as a reinforcing component offers a promising solution, enhancing overall performance and reliability. A multifunctional composite hydrogel incorporating MXene and Fe₃O₄ nanoparticles has been developed for simultaneous pressure, magnetic field, and temperature sensing. This system can monitor human joint movements while responding to magnetic and thermal stimuli, significantly expanding the application scope of MXene-based hydrogels in smart wearable devices (Figure a). The combination not only improves electrical conductivity but also enhances multi-responsive capabilities. When extending applications to extreme low-temperature environments such as polar regions, high altitudes, or space exploration, anti-freezing properties and mechanical robustness become critical considerations. Li et al. designed a tannic acid (TA)@MXene semi-interpenetrating network hydrogel that maintains excellent pressure sensing capability and operational stability even under subzero conditions (Figure b). In a separate development, Han et al. created a MXene-loaded poly­(vinyl alcohol) (PVA)/thioctic acid organohydrogel for pressure sensing applications. When integrated with deep learning algorithms, this sensor demonstrates capabilities in letter recognition and human motion monitoring. In summary, the integration of MXene with hydrogels has successfully created sensing platforms combining high biocompatibility, excellent flexibility, and superior electrical conductivity. Current research has progressed beyond simple physical blending to advanced strategies including integrated gelation, incorporation of functional fillers (liquid metal/magnetic nanoparticles), and construction of semi-interpenetrating networks. These approaches simultaneously enhance electrical conductivity, mechanical strength, oxidation resistance, anti-freezing capability, and multi-responsive performance, enabling the transition from single-mode pressure sensing to multi-modal detection of temperature, magnetic fields, and other stimuli.

7.

MXene-based hydrogel flexible pressure sensors. (a) Fabrication process of the poly­(N-isopropylacrylamide)/MXene nanosheet/Fe₃O₄ hydrogel sensor. Reproduced with permission from ref . Copyright 2025 American Chemical Society. (b) Preparation and applications of the TA@MXene hydrogel pressure sensor. Reproduced with permission from ref . Copyright 2025 Wiley.

However, fundamental challenges remain regarding the long-term chemical stability and uniform dispersion of MXene within hydrogel networks. Furthermore, reliable adhesion and long-term service stability under complex physiological conditions, particularly at dynamic and hydrated interfaces, require further validation. Additionally, developing high-precision, patternable, and environmentally friendly fabrication processes to meet practical application demands represents another critical direction for future research. Future investigations should focus on developing more stable encapsulation strategies or self-healing mechanisms to extend device lifetime, exploring more biocompatible and robust interface integration schemes, and promoting the deep integration of deep learning-based data fusion and recognition algorithms with multi-modal hydrogel sensors. These advancements will ultimately enable full-chain application value in personalized healthcare, soft robotics, and extreme environment exploration.

Table summarizes the sensing performance of recently reported MXene-based flexible sensors, revealing a broad diversity in material architectures, ranging from 1D fibers and 2D papers/fabrics to 3D foams, aerogels, and hydrogels. A critical analysis of the data demonstrates the tunable nature of these sensors, particularly regarding the inherent trade-off between sensitivity and sensing range. For instance, the CNF/MXene/AgNPs composite achieves an exceptionally high sensitivity of up to 136.7 kPa^–1 within a moderate pressure range (0.5–80 kPa). In stark contrast, the Stainless steel core-polyester/MXene sensor sacrifices high sensitivity (0.14–0.93 kPa^–1) to obtain an ultra-broad sensing range spanning from 7.2 Pa to an impressive 15,000 kPa.

3. Quantitative Summary of MXene Stability Parameters, Including Oxidation Onset Temperatures, Shelf-Life, and Washing Durability Across Representative Studies.

materials	type	sensitivity	sensing range	response time	reliability	ref
polyester-spandex/CS/MXene/PDMS	piezoresistive	15.135 kPa–1 (0–32.7 kPa)	0–552.87 kPa	–	–
stainless steel core-polyester/MXene	piezoresistive	0.14–0.93 kPa–1	7.2 Pa-15000 kPa	80 ms	10,000 cycles (81.25% retained)
cellulose paper/MXene	piezoresistive	1.25–36.87 kPa–1	0–79 kPa	113/81 ms	10,000 cycles
cellulose paper/MTS/MXene	piezoresistive	11.95–39.58 kPa–1	0–60 kPa	69–161 ms	10,000 cycles
cellulose paper/graphene/SWNTs	piezoresistive	4.3–12.6 kPa–1	0.03–60.4 kPa	<380 ms	4000 cycles
melamine foam/MXene/EMIM-TFSI	ionic conductive	0.128–5.067 kPa–1	0–60 kPa	28/18 ms	>7000 cycles
silicone foam/MXene/CNTs	piezoresistive	0.45–2.42 (GF)	0–70% strain	50/45 ms	1000 cycles
SSE foam/MXene	piezoresistive	9.79 ΔR/R0/σ	–	5.4 s	30% strain stable
CNF/MXene/AgNPs	piezoresistive	23.74–136.7 kPa–1	0.5–80 kPa	50/60 ms	20,000 cycles
PAM/CMC/TA@MXene/glycerol	piezoresistive hydrogel	0.15–5.4 kPa–1	0–18 kPa	105/135 ms	100 cycles
cotton fabric/MXene/PFOTES/AgNWs	piezoresistive fabric	–	–	–	humid/hot stable
PU foam/CS/MXene	piezoresistive	–	–	–	mech. stable
TOCNF/MXene/MWCNT	multimodal aerogel	–	–	–	humidity/pressure/light
PI/MXene/AgNWs	piezoresistive aerogel	–	–	–	high strength
O-BC/MXene	piezoresistive aerogel	–	–	–	compression recovery
PNIPAM/MXene/Fe3O4	trimodal hydrogel	–	–	–	joint monitoring
knitted fabric/CS/PDA/MXene	piezoresistive fabric	–	–	–	underwater stable
silicone foam/MXene/CNTs/Karstedt	piezoresistive	0.45–2.42 (GF)	0–70% strain	50/45 ms	1000 cycles

Furthermore, the integration of MXenes with various structural matrices significantly enhances dynamic response and long-term durability. Notably, the Melamine foam/MXene/EMIM-TFSI ionic sensor exhibits a rapid response/recovery time of 28/18 ms, while the CNF/MXene/AgNPs device maintains stable operation over an outstanding 20,000 loading–unloading cycles. Beyond standard piezoresistive capabilities, there is a clear developmental trend towards multifunctionality and extreme-environment reliability. Recent advancements such as the trimodal hydrogel for joint monitoring, the multimodal aerogel responsive to humidity, pressure, and light, and the knitted fabric sensor capable of underwater operation-highlight the immense potential of MXene composites in complex, real-world continuous monitoring scenarios.

4. Structural Design of MXene-Based Flexible Pressure Sensors

While the high electrical conductivity and intrinsic flexibility of MXene provide a solid foundation for its application, issues such as nanosheet restacking and interfacial instability continue to constrain electromechanical coupling stability. Structural design of MXene-based flexible pressure sensors has emerged as a key strategy for enhancing device performance, with research focus evolving from simple geometries to multi-scale, continuous architectures. Based on sensing mechanisms and material assembly approaches, current structural designs primarily encompass micro-scale bio-inspired geometric substrates, thin-film/interlayer interface regulation, fiber-to-textile macro-system integration, and multi-modal coupling for achieving intelligent, closed-loop response systems.

4.1. 1D Fiber and Textile-Integrated Structural Design

Breakthroughs in MXene-based flexible pressure sensors for wearable electronics are closely tied to innovations in fiber and textile architectures. Techniques such as dip-coating, coating, and wet-spinning have been employed to composite MXene with polymers, forming weavable conductive fibers capable of real-time monitoring of multimodal stimuli including pressure, tensile strain, and bending. Although fiber-based structures offer skin conformability and large-area compatibility, conventional single-layer coating often results in uneven conductive networks and response hysteresis, limiting improvements in sensitivity and detection range.

To address these limitations, researchers are focusing on material synergy and structural engineering to develop piezoresistive mechanisms with low hysteresis. This involves a multi-stage process, progressing from increasing micro-scale contact points to the integration of macro-scale array structures. Among these, constructing heterogeneous composite structures of MXene and other nanomaterials through synergistic material optimization can enhance interfacial adhesion and improve the uniformity of the conductive network. For instance, sequential coating of MXene with reduced graphene oxide (rGO) on poly­(ethylene terephthalate) (PET) yarn creates a dense conductive network while ensuring strong interfacial adhesion, leading to improved sensitivity and an extended sensing range (Figure a). Similarly, introducing a 1D/2D heterostructure of AgNWs and MXene via sequential dip-coating optimizes conductive pathways, achieves high sensitivity (e.g., >1000 kPa^–1 in the low-pressure regime) in a two-electrode configuration, supports array-based wireless data transmission, and enables applications like gesture recognition. The active area of a single sensing pixel in the textile array was approximately 5 × 5 mm², although the MXene mass loading was not quantified in the source (Figure b). Further development includes MXene/Ag nanoflower composite coatings, where the nanoflower morphology increases micro-contact points, resulting in exceptional sensitivity (Figure c).

8.

1D fiber and textile-integrated structural flexible pressure sensors. (a) Fabrication process of the MXene/rGO-PET flexible pressure sensor. Reproduced with permission from ref . Copyright 2022 American Chemical Society. (b) Preparation process of the AgNWs/MXene bilayer textile flexible pressure sensor. Reproduced with permission from ref . Copyright 2023 American Chemical Society. (c) Structural design of the MXene/Ag nanoflowers/cotton fabric pressure sensor and diagram of the sensor device. Reproduced with permission from ref . Copyright 2025 Royal Society of Chemistry. (d) Core–sheath structure design of the carbon black/PDMS/MXene ternary composite yarn and schematic of the sensing array. Reproduced with permission from ref . Copyright 2024 Elsevier B.V. (e) Surface morphology and SEM image of the superhydrophobic yarn sensor with a wrinkled structure. Reproduced with permission from ref . Copyright 2025 American Chemical Society. (f) Fabrication process and structural design of the MXene/PET-based textile flexible pressure sensor. Reproduced with permission from ref . Copyright 2023 Royal Society of Chemistry.

Yarn structure design can enhance the multi-modal sensing capabilities of these sensors. Specifically, a ternary composite yarn comprising carbon black/PDMS/MXene, integrated with a multi-electrode array, enables a single sensing pixel to decouple pressure, tensile, and bending signals. Through embroidery techniques, these composite yarns are embedded into textiles to create large-area fabric sensors, effectively addressing challenges related to system integration and wearable compatibility (Figure d). However, advancing the practical application of MXene-based fiber sensors in intelligent wearables requires solving the core issue of environmental robustness, specifically, maintaining signal stability and long-term durability under complex physiological conditions. To this end, Hang et al. spray-coated dopamine-modified MXene onto polyester yarns to impart superhydrophobicity, ensuring signal stability during perspiration and movement (Figure e). Cheng et al. introduced hierarchical structures at fabric interfaces, achieving integrated structural and functional design that enhances interfacial adhesion and electrical stability. Recent innovations are also evident in signal decoupling and smart system integration. Wang et al. developed a humidity-pressure dual-modal yarn encapsulated within a porous skeleton, which was woven into a smart wristband capable of bluetooth control and wound monitoring. Zhang et al. utilized geometrically tunable pores and a contact-compaction mechanism to maintain high sensitivity in underwater environments, expanding applications into the field of soft robotics (Figure f).

In summary, research has progressed from initial simple material coating to the precise construction of stable and efficient conductive networks through multi-material synergy like MXene/rGO and MXene/AgNWs, and hierarchical structural designs involving core–sheath and heterogeneous composite coatings. This evolution has significantly enhanced sensor sensitivity, sensing range, and multi-modal signal decoupling capability. , Strategies like superhydrophobic modification and hierarchical interfacial structures have effectively improved device robustness and long-term stability in complex environments such as sweat and underwater, enabling preliminary system-level integration with wireless communication and intelligent algorithms.

However, challenges remain in manufacturing consistency, cost control, and effectively suppressing cross-talk between multiple physical signals during dynamic wear for accurate decoupling, which currently hinder large-scale practical application. Future research should shift its focus from performance optimization to system intelligence aiming to develop closed-loop wearable systems that integrate energy harvesting, information sensing, edge computing, and feedback execution. The ultimate goal is to realize next-generation smart textiles capable of self-powering, real-time diagnostics, and intelligent interaction through the integrated weaving of fiber sensors with triboelectric nanogenerators, fiber-based batteries, and microchips.

4.2. 2D Thin-Film/Layered Composite Structural Design

Within the multi-scale continuum framework, 2D polymer thin films/interlayers serve as buffer layers to mitigate MXene nanosheet instability. Techniques such as electrostatic self-assembly or 3D printing enable the formation of uniform conductive networks and reversible interfacial deformation, thereby enhancing structural stability. 2D thin-film materials, characterized by their large surface area, excellent flexibility, and high stability, significantly amplify responses under the synergistic effect of piezoresistance and quantum tunneling. Under applied pressure, interlayer compression not only reduces the tunneling distance but also increases contact points via interlocked interlayers, thereby extending the linear response range.

Despite the significant sensing advantages of 2D layered structures, their electromechanical coupling stability under long-term cyclic loading remains a critical challenge for practical applications. Due to the severe modulus mismatch between rigid MXene nanosheets and flexible polymer substrates, microcracks are prone to initiate at the heterogeneous interface owing to stress concentration during high-frequency dynamic deformation. This subsequently triggers delamination or interlayer sliding within the conductive networks. Macroscopically, such irreversible microstructural damage manifests as continuous baseline resistance drift and hysteresis effects. Consequently, recent research focuses have shifted toward enhancing the interlayer shear strength via interfacial engineering. For instance, Zheng et al. reported a multilayer composite film based on f-MXene functionalized with silanization agents. By constructing a hydrophobic protective layer through electrostatic self-assembly, the oxidative degradation of MXene during service was effectively suppressed. Experimental results demonstrated that the sensor exhibited a minimal resistance variation of approximately 0.8% after 30 days of exposure to ambient conditions. Furthermore, it maintained a stable resistance response over 1000 loading/unloading cycles at 50 kPa, with response and recovery times of 180 ms and 200 ms, respectively. This milestone signifies that 2D layered structures are transitioning from the singular pursuit of high sensitivity toward high environmental robustness and extended service life.

An innovation in 2D thin-film structures involves combining MXene thin films with a PDMS encapsulation layer. This design enables temperature-compensated, decoupled pressure–temperature dual-mode detection. Utilizing a simple inkjet printing process, this approach offers high stability and reliability (Figure a,b). The former method involves layer-by-layer stacking to form a film, allowing rapid deposition and patterning on flexible substrates to create a uniform, continuous primary conductive layer. In contrast, a hydrogen-bonding-driven self-assembly mechanism forms a metal–organic framework (MOF)@MXene layered composite, which is embedded into poly­(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) fibers, creating a multi-scale layered architecture. Porous 2D thin films provide flexibility and a high specific surface area, forming a multi-scale layered structure ranging from the atomic level to macroscopic fiber membranes (Figure c). This architecture concurrently exhibits nanoconfinement effects and interfacial polarization, effectively stabilizing dipole orientation and enhancing charge migration, thereby significantly improving the piezoelectric coefficient and sensing sensitivity.

9.

2D thin-film/layered composite structured flexible pressure sensors. (a) Schematic diagram of the sensing layer and encapsulation layer in the fully resistive dual-mode sensor. Reproduced with permission from ref . Copyright 2024 Elsevier B.V. (b) Fabrication process of the fully resistive dual-mode sensor. Reproduced with permission from ref . Copyright 2024 Elsevier B.V. (c) Preparation process of the MOF@MXene flexible pressure sensor. Reproduced with permission from ref . Copyright 2024 Elsevier B.V. (d) Assembly process of the thermoplastic TPU/c-MWCNTs/MXene layered composite structured flexible pressure sensor. Reproduced with permission from ref . Copyright 2024 Elsevier B.V.

While the fabrication process for 2D thin films is straightforward, performance enhancement remains a bottleneck. Layered composite structures can overcome these limitations through interlayer optimization, achieving performance leaps and making them more suitable for practical engineering applications. Consequently, research has begun exploring layered composite structures to realize synergistic amplification effects. A recent study reported a multi-layer sensor structure based on an electrospun conductive film of thermoplastic polyurethane (TPU)/carboxylated multi-walled carbon nanotubes (c-MWCNTs)/MXene. This design includes a top PDMS substrate with discontinuous spine-like microstructures, a middle porous 3D nanofiber conductive network, a TPU fiber spacer layer, and bottom interdigitated electrodes (Figure d). The primary innovation of this design lies in the incorporation of spine-like microstructures and a spacer layer, which collectively enable a two-stage amplification mechanism. In the low-pressure regime, the deformation of these microstructures facilitates the rapid formation of new conductive paths, thereby enhancing pressure concentration and achieving high sensitivity. In the high-pressure regime, the expansion of these conductive paths helps to maintain a linear response. This innovation shifts the paradigm from traditional, less efficient sensors and advances wearable applications in physiological signal monitoring and spatial pressure mapping, marking a transition from purely 2D thin films to functional layered composites.

The structural design of MXene-based 2D thin films/layered composites has evolved from pursuing uniform conductivity to achieving intelligent regulation of sensing performance through sophisticated micro–nano structures and multi-material systems. The current research focus leverages the synergistic deformation and charge transport mechanisms at multilayer interfaces. Strategies like the “two-stage amplification” effectively eliminate the mechanical mismatch and directly drives the realization of high-performance pressure sensing across epidermal, robotic, and industrial domains. However, advancing these sensors from the laboratory to practical applications requires solving challenges related to the large-scale, high-consistency manufacturing of complex multilayer structures and ensuring the mechanical and electrical stability of interlayer interfaces under long-term cyclic loading. Future research in this field should place greater emphasis on the integrated design of structure–function-application. On one hand, developing intelligent layered structures based on biomimetic principles that can adapt to different pressure ranges or environmental stimuli is crucial. On the other hand, it is essential to explore monolithic systems that integrate flexible circuits and energy units, enabling the development of intelligent sensing patches capable of real-time signal processing and self-powering. These efforts will ultimately lead to groundbreaking applications in health monitoring and sensory skins for soft robotics.

4.3. 3D Porous Sponge Network Structural Design

The 3D porous sponge architecture represents a volumetric innovation for MXene-based sensors, utilizing freeze-drying, salt leaching, or bubble foaming to construct interconnected pore networks. This approach enables uniform stress distribution and continuous electrical pathways, overcoming the planar limitations of 2D thin films while maintaining low modulus and superelasticity even under high loads.

While bidirectional freeze-casting remains a mainstream fabrication technique, recent research has shifted toward bubble foaming and sacrificial templating to optimize the interlayer network. For instance, Zhang et al. constructed a 3D MXene aerogel via bubble foaming, where catalytically decomposed H₂O₂ generates CO bubbles that rapidly form an interconnected macroporous network within the MXene aqueous dispersion. By controlling volumetric compression to amplify the piezoresistive response, they achieved a gauge factor of 306 kPa^–1 (two-electrode configuration, active area: 1 cm², MXene mass loading: ∼0.5 mg/cm²), significantly enhancing the utilization of MXene’s surface metallic conductivity (Figure a,b). Similarly, a sacrificial template method was used to fabricate an MXene/CNF@PDMS aerogel flexible pressure sensor. The resulting superelastic structure enhances hydrogen bonding interlocking, achieving a detection limit lower than 4.3 × 10^–4 kPa, suitable for capturing subtle dynamic pressures. The mechanism relies on anisotropic channels formed after template removal, which amplify stress gradients and enable decoupled bending/stretch sensing (Figure c).

10.

3D porous sponge network structured flexible pressure sensors. (a) Schematic of the fabrication process and sensor assembly for the 3D MXene aerogel flexible pressure sensor. Reproduced with permission from ref . Copyright 2022 American Association for the Advancement of Science. (b) SEM images and porosity variation during dynamic compression and release of the 3D MXene aerogel flexible pressure sensor. Reproduced with permission from ref . Copyright 2022 American Association for the Advancement of Science. (c) Structural design and working mechanism of the MXene/CNF@PDMS dual-mode aerogel pressure sensor. Reproduced with permission from ref . Copyright 2025 Wiley-VCH Verlag. (d) Structural design and SEM images of the honeycomb-structured flexible pressure sensor. Reproduced with permission from ref . Copyright 2025 American Chemical Society. (e) Preparation process and structural design of the PVA/CS-MXene hydrogel flexible pressure sensor. Reproduced with permission from ref . Copyright 2024 Elsevier B.V. (f) Fabrication and assembly of the MXene/CNFs flexible pressure sensor electrode. Reproduced with permission from ref . Copyright 2025 American Chemical Society.

Functional enhancements in 3D structural sensors focus on multi-physics coupling, emphasizing interface modification and AI assistance to broaden application boundaries. Using a 3D porous structure as a substrate addresses the brittleness and oxidation issues of conductive materials in traditional flexible sensors. For example, silicone rubber (SR) serves as a binder to construct a “honeycomb structure” resembling a hexagonal grid, providing abundant attachment sites. Alternating immersion in carbon black/MXene conductive solution and SR adhesive solution enhances conductive path stability and mechanical strength (Figure d). This design mitigates MXene oxidation and brittleness, achieving low hysteresis and low creep, which is unlike traditional planar or single-layer coated sensors. In another study, a PVA/CS-MXene sponge formed via ice-templated freeze-casting developed unidirectional porous pathways in a double-network hydrogel. The collapse of corrugated pore walls amplifies the tunneling effect, achieving an exceptionally low gauge factor of 0.0187 kPa^–1 (Figure e). Furthermore, an MXene/rGO synergistic aerogel combined with a convolutional neural network (CNN) enables fitness posture recognition. Using a 7-channel array to decouple joint/heel signals, it supports human–computer interaction and wearable health tracking, maintaining high stability even after washing. , These coupling strategies not only amplify the piezoresistive response but also suppress noise interference through frequency stability, providing tactile feedback for soft robotics. To address mechanical inhomogeneity in 3D porous sponge networks, breakthroughs have been made by regulating pore evolution and nanoscale interlayer engineering. For example, uniformly integrating 1D CNFs into a MXene nanoscale colloidal solution forms a composite for preparing MXene/CNFs films. The insertion of CNFs between MXene layers suppresses van der Waals interactions, increasing interlayer spacing and enhancing mechanical strength (Figure f).

In summary, 3D porous sponge networks leverage their unique volumetric effects and interconnected channels to deliver breakthrough performance enhancements for MXene flexible pressure sensors. Current research frontiers have expanded from traditional freeze-drying to more precise pore-forming techniques such as bubble foaming and sacrificial templating, enabling active control over pore morphology, size, and distribution. This significantly improves sensor sensitivity, detection limit, and elastic recovery. Moreover, through multi-material compounding and bio-inspired interface modification, inherent challenges like MXene nanosheet restacking, oxidation, and mechanical brittleness in 3D networks are effectively mitigated. The integration with artificial intelligence such as CNN marks a transition for these sensors from simple signal acquisition units to intelligent systems capable of complex pattern recognition and decision-making.

Future efforts should focus on core manufacturing challenges, particularly ensuring uniformity in pore structure and consistency in mechanical properties at macroscopic scales. The long-term structural fatigue stability under complex dynamic loading also requires in-depth evaluation. Developing more controllable, environmentally friendly, and industrially compatible mass-production technologies such as continuous foaming processes is essential. Concurrently, exploring the integration of 4D printing with 3D porous structures could enable next-generation smart sensors that adaptively modify their morphology and function in response to external stimuli including temperature and magnetic fields. Ultimately, by deeply integrating sensing, energy supply, and computing, these advances will drive revolutionary applications in smart prosthetics, precision health monitoring, and sensory systems for soft robotics.

4.4. Emerging Biomimetic Structural Design

As wearable electronics and intelligent sensing technologies advance toward higher performance and multifunctionality, emerging trends are increasingly incorporating bio-inspired structural designs. Drawing inspiration from biological systems helps overcome limitations such as nanosheet restacking, oxidation sensitivity, and narrow sensing ranges. , Learning from natural micro-architectures enables a balance among high sensitivity, fast response, and durability in polymer/MXene-based flexible sensors. For example, inspired by the brick-and-mortar layered structure of nacre, researchers have used bidirectional freeze-casting to construct aligned 3D hierarchical porous networks. This lamella-bridge configuration simultaneously provides strength, toughness, and electrical conductivity, forming a robust piezoresistive sensing substrate (Figure a,b). Another design mimics the hierarchical tracheid structure of natural wood, creating aligned channels of CNFs, CNTs, and MXene. Interfacial interlocking enhances electron transport and stress transfer, while the ordered tracheid-like structure and continuous conductive network significantly improve electrical conductivity, enabling high sensitivity at low pressures and excellent fatigue resistance (Figure c,d). It can be inferred that a hierarchical heterogeneous integration strategy can be adopted. This design features a top nacre-like multilayer for impact resistance, a middle layer with an artificial neural cage-synapse structure to mimic biological signal transmission for high-sensitivity sensing, and a bottom porous brick-like layer for stability. Consequently, a multifunctional device can be realized, integrating pressure perception, EMI shielding, actuation, and degradability.

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Emerging bio-inspired flexible pressure sensors. (a) Fabrication process of the nacre-inspired brick-and-mortar structured MXene-GO composite foam flexible pressure sensor. Reproduced with permission from ref . Copyright 2021 American Chemical Society. (b) 3D reconstruction of the porous structure and microscopic morphology image of the lamellar structure in the nacre-inspired MXene-GO composite foam flexible pressure sensor. Reproduced with permission from ref . Copyright 2021 American Chemical Society. (c) Schematic diagram of the compression deformation mechanism in the wood tracheid-inspired CNFs/CNTs/MXene aerogel flexible pressure sensor. Reproduced with permission from ref . Copyright 2023 Springer Nature. (d) Schematic illustration of ion and electron transport processes within the electrode of the wood tracheid-inspired CNFs/CNTs/MXene aerogel flexible pressure sensor before and after compression. Reproduced with permission from ref . Copyright 2023 Springer Nature.

Natural micro-surface structures, known for their excellent mechanical regulation and energy conduction capabilities, provide critical insights for constructing high-performance artificial sensing systems. By emulating the morphological and mechanical characteristics of various biological surfaces, researchers have developed multiple innovative structural strategies. , For instance, inspired by the micro-hooks on the surface of burrs, zinc oxide nanowires were grown on electrospun polyurethane nanofiber membranes to create hook-like fibers (Figure a). Two such ZnO@polyurethane membranes were aligned and pressed together with a relative offset, forming a 3D interlocked structure (Figure b). Under pressure, the upper and lower ZnO nanowire hooks gradually contact and interlock, increasing the number of conductive pathways and producing a linear, controllable resistance change. Similarly, the papillae on a cat’s tongue, which flex, catch, and release during licking for efficient friction control, inspired a reversible interlocking and stress-regulation mechanism. Using 3D printing, a hard template mimicking the tongue papillae was fabricated, and a flexible negative mold was replicated in PDMS. A CNTs/PDMS mixture was then cast into the mold and cured, producing a flexible film with a bio-inspired papilla array (Figure c). Two such films facing each other form a 3D interlocking structure that enables gradual contact and stress migration between papillae under pressure, achieving both high sensitivity and a wide sensing range (Figure d). Furthermore, inspired by the mechanosensory system of scorpions, a high-performance bioinspired piezoresistive pressure sensor (BPPS) with a synergistic front-and-back bio-inspired structure was developed. A slit-like stress trap on the front silicon membrane enhances local strain response, while claw-like anti-bending supports on the back achieve an optimal balance between localized amplification and overall stability. Simulations and experiments confirm that this sensor successfully combines high sensitivity, superlinearity, and a broad detection range (two-electrode configuration, effective electrode area: 0.25 cm², MXene content: ∼0.2 mg) (Figure e,f).

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Emerging bio-inspired flexible pressure sensors. (a) Schematic diagram of the preparation process for the sensitive layer in the 3D interlock-structured flexible pressure sensor inspired by burrs. Reproduced with permission from ref . Copyright 2025 Wiley-VCH Verlag. (b) Structural schematic and electron micrograph of the 3D interlock-structured flexible pressure sensor inspired by burrs. Reproduced with permission from ref . Copyright 2025 Wiley-VCH Verlag. (c) Structural design concept and applications of the flexible pressure sensor inspired by feline tongue filiform papillae. Reproduced with permission from ref . Copyright 2025 Wiley-VCH Verlag. (d) Fabrication process of the flexible pressure sensor inspired by feline tongue filiform papillae. Reproduced with permission from ref . Copyright 2025 Wiley-VCH Verlag. (e) Structural assembly of the high-sensitivity pressure sensor inspired by the scorpion’s mechanoreception mechanism. Reproduced with permission from ref . Copyright 2025 American Association for the Advancement of Science. (f) Schematic diagram of the structural design concept for the high-sensitivity pressure sensor inspired by the scorpion’s mechanoreception mechanism. Reproduced with permission from ref . Copyright 2025 American Association for the Advancement of Science.

Although some biomimetic designs still rely on conventional piezoresistive mechanisms, their necessity lies in overcoming the inherent trade-off between sensitivity and sensing range found in traditional planar structures through the nonlinear mechanical regulation of geometric morphologies. Firstly, biomimetic microstructures (e.g., cat-tongue papillae or crack structures) induce significant stress concentration effects. This causes drastic variations in the contact resistance between MXene layers under minute applied pressures, thereby endowing the sensors with ultrahigh sensitivity in the low-pressure regime. Secondly, biomimetic stepped or interlocked architectures enable a progressive, pressure-dependent increase in contact area. This prevents the premature saturation of conductive pathways and effectively broadens the linear response range. Ultimately, this paradigm shift from material-intrinsic response to system-level mechanical regulation constitutes the core added value in enhancing the robustness of MXene sensors for capturing complex physiological signals. These emerging bio-inspired designs employ a reversible synergistic mechanism of contact point multiplication and conduction/tunneling channel shortening to amplify electrical response and suppress hysteresis, enabling array-based human–computer interaction integrated with algorithms. ,

The justification for biomimicry in MXene-based sensors extends beyond mere morphological imitation. While the underlying transduction often remains the piezoresistive effect, bionic architectures act as essential mechanical signal modulators. For instance, mimicking the interlocking micro-structures of human skin localizes strain at high-aspect-ratio contact points to amplify sensitivity, while the hierarchical porosity of wood or bone provides a gradient of mechanical stiffness that prevents the early saturation of conductive network densification. By providing a degree of structural precision honed by natural evolution, biomimicry allows for the independent tuning of sensitivity, detection range, and mechanical durability-metrics that are often mutually exclusive in traditional stochastic composites. Consequently, bio-inspired design has become a leading core driver for advancing the performance boundaries of polymer/MXene-based sensors, resolving inherent trade-offs through functional replication of natural micro-architectures. Looking forward, the field will evolve toward multi-biomodel fusion, dynamic biomimetics via 4D printing, and ultimately, system-level biomimetics. By integrating sensing units with neuromorphic hardware and neural-inspired signal processing, these intelligent systems will pave the way for next-generation adaptive robotics and advanced human-machine interaction.

As shown in Figure , 2D thin-film structures exhibit rapid responses at low pressures and excellent stability, but are prone to a degradation in sensitivity under high pressures. In contrast, 3D structures generally facilitate the realization of comprehensive performance, characterized by high low-pressure sensitivity, an ultra-low limit of detection (LOD), and an outstanding cyclic lifespan. Among these, porous networks possess substantial compressible deformation capacity. Even under minute applied loads, they can undergo significant pore collapse and contact state reconfiguration, thereby triggering a rapid increase in both the number of conductive pathways and the contact area. In comparison, the advantages of biomimetic microstructures are predominantly reflected in their ability to maintain responsiveness across a broad dynamic range. Specifically, they exhibit ample tunability in the low-pressure regime while resisting premature saturation during the high-pressure stage.

13.

Performance comparison of polymer/MXene-based sensors with different structures. The x-axis represents the upper limit of the sensing range, P _max (kPa, log scale), and the y-axis represents the sensitivity (kPa^–1, log scale). The bubble size indicates the cyclic stability (number of loading–unloading cycles), with larger bubbles corresponding to a higher cycle count. The data points in the figure correspond to various devices reported in the literature, including MXene/AgNWs, MACF, MSF, PPy-grafted porous PDMS, all-resistive dual-mode multifunctional MXene aerogel, MXene/PPy@PDMS, TPU/ZnO NWs 3D interlocking, and FPsp.

5. Applications of MXene-Based Flexible Pressure Sensors

5.1. Vital Signs Monitoring

Leveraging their unique chemical and physical properties, MXene-based sensors demonstrate significant advantages in the field of smart wearables. These sensors are capable of monitoring various physiological signals including joint flexion, pulse, respiration, heart rate, and facial expressions, holding considerable promise for advancing personalized health management (Figure ).

14.

Applications of polymer/MXene-based flexible pressure sensors.

5.1.1. Pulse Wave Monitoring

Substantial progress has been made in applying MXene-based flexible pressure sensors to pulse wave monitoring for healthcare. A typical performance evaluation involves connecting the sensor to a controlled loading setup and using a source meter to record current/resistance versus time, thereby determining the operating voltage and signal stability. The sensor is then attached to the target area, effectively converting subtle mechanical vibrations into electrical signals. During signal acquisition, outputs can be transmitted via wired or wireless connections to a microcontroller or mobile device, with bluetooth modules often enabling real-time data transfer. The acquired periodic waveforms are analyzed to calculate heart rate and extract detailed pulse wave characteristics for further assessment. The pulse waveform typically contains three characteristic peaks, the primary wave (P1), the tidal wave (P2), and the dicrotic wave (P3). Among them, P1 reflects the impact wave generated by left ventricular contraction, P2 represents the superposition of late-systolic reflected waves, and P3 corresponds to the vibration caused by aortic valve closure at the onset of diastole. Zhang et al. developed a flexible three-channel sensing array based on MXene/PET, which was closely affixed to the wrist, neck, or specific locations in traditional Chinese medicine such as the Cun, Guan, and Chi positions. The system captured raw pulse and pressure signals, extracting clinically relevant waveform features including P1, P2 and P3. In pre- and post-exercise comparisons, the volunteer’s pulse rate increased from 78 bpm to 98 bpm, with noticeable changes in waveform morphology, demonstrating the system’s sensitivity to physiological changes.

Multifunctional flexible pressure sensors can simultaneously monitor pulse pressure and respiratory rate, serving as versatile wearable devices. By capturing pulse waves and breathing patterns, applying voltage, and analyzing I–V characteristics (Figure a), physiological data such as pulse waveform and respiratory rate can be extracted. These morphological features can be further utilized to assess conditions like arterial stiffness. Biocompatible materials are typically employed to ensure skin safety during prolonged wear. An MXene-based antibacterial conductive alginate hydrogel sensor has been developed for pulse monitoring. Leveraging the material’s inherent antibacterial and self-adhesive properties, the sensor was fixed with insulating tape and tested for finger bending and radial artery pulse detection. When attached to the radial artery, it produced regular pulse wave signals with a period of 66.7 beats per minute and a rise time of 150 ms (Figure b). This approach offers new possibilities for wearable devices in clinical environments, particularly for pulse monitoring and cardiovascular health assessment. Beyond hydrogels, a waterproof flexible pressure sensor was fabricated via electrostatic self-assembly of silica (SiO₂)/MXene/NH₂–CNTs (SMCM) on a melamine sponge skeleton. By attaching the sensor to the radial artery of the wrist for signal acquisition, the pulse signals can be clearly detected, exhibiting distinct P1 and P2 waveforms (Figure c). The electrostatic self-assembly method enables precise nanomaterial positioning, enhancing sensor sensitivity and response speed for more accurate signal acquisition. To improve wearing comfort, an interlayer design using MXene/cotton/spandex fabric sandwiched between polyurethane film and PI sheets was developed to form interdigitated electrodes. This textile pressure sensor, attached to the radial artery, captured real-time pulse waveforms and recorded 10 continuous pulse cycles within 7 s, allowing accurate heart rate measurement. The waveforms clearly displayed P1, P2 and P3. A portable wireless sensing system was also constructed by connecting the sensor to a bluetooth-enabled microcircuit, enabling signal transmission to a mobile device for recording and display. This system shows potential for wearable motion monitoring and human–machine interaction (Figure d).

15.

MXene-based flexible pressure sensors for pulse wave monitoring. (a) Schematic diagram of the MXene/CS-based flexible pressure sensor for health monitoring and its real-time pulse wave recording. Reproduced with permission from ref . Copyright 2021 American Chemical Society. (b) Real-time pulse wave monitoring using an antibacterial MXene/alginate conductive hydrogel sensor. Reproduced with permission from ref . Copyright 2023 Elsevier B.V. (c) Wireless transmission device based on the silica (SiO₂)/MXene/NH₂–CNTs waterproof flexible pressure sensor. Reproduced with permission from ref . Copyright 2023 American Chemical Society. (d) Photograph of the MXene/cotton/spandex fabric pressure sensor worn on the wrist and its application in pulse wave monitoring. Reproduced with permission from ref . Copyright 2023 Elsevier B.V.

In summary, studies have shown that MXene-based sensors whether through multi-channel arrays for capturing subtle pulse features, antibacterial hydrogels, waterproof sponges, or comfortable textiles, can reliably extract complete pulse wave information, including primary, tidal, and dicrotic waves. The successful integration of wireless modules further enables portable real-time monitoring, demonstrating both excellent performance and diverse implementation pathways for MXene sensors in pulse monitoring. These advances highlight the potential for shifting health monitoring from intermittent, hospital-centered measurements to continuous, personalized, and home-based tracking. However, several challenges must be addressed to translate this potential into clinical-grade diagnostic tools. Future work should focus on enhancing the clinical interpretability of signals through larger-scale validation, establishing quantitative models that link pulse waveform features to specific cardiovascular diseases like arteriosclerosis and hypertension. It is also essential to mitigate the effects of individual differences and environmental interference by developing smart sensors with self-calibration capabilities. Finally, building closed-loop of sensing, diagnosis and feedback systems that integrate high-precision pulse monitoring with AI-assisted diagnostics, cloud-based health records, and clinical alert mechanisms will be crucial. Such integration will ultimately elevate the role of wearable sensors from monitoring to management, providing powerful technological support for early screening and long-term tracking of cardiovascular diseases.

5.1.2. Respiration and Heartbeat Monitoring

Respiration and heartbeat have become two of the most targeted vital signs in wearable technology. MXene-based flexible pressure sensors enable precise monitoring of these physiological signals, leveraging their core advantages of conformal contact with curved body surfaces and real-time detection of subtle physiological fluctuations. The healthcare field is currently shifting from traditional static monitoring toward dynamic, continuous tracking, which not only records baseline parameters but also accurately captures vital sign variations during physical activity. In practical application, the sensor is attached to the skin surface such as the wrist, neck, or back, where physiological signals can be sensitively detected. It captures minor pressure changes induced by breathing and cardiac activity. During signal acquisition, the sensor records weak pressure differences via variations in capacitance. The raw signal is subsequently filtered to effectively separate respiratory and cardiac components. In the signal analysis stage, respiratory rate is derived by calculating the time difference between peaks in the filtered signal, while heartbeat signals are processed using peak detection algorithms to extract heart rate. After attaching the nanofiber-reinforced MXene–rGO aerogel piezoresistive sensor to the wrist, the three characteristic peaks of P1, P2, and P3 can be clearly distinguished (Figure a). The same sensor is also capable of identifying different pronunciations, generating corresponding distinct electrical signal waveforms. In another example, a honeycomb-like AuCu alloy nanoparticle-modified MXene/rGO composite aerogel was applied to the carotid artery, acquiring clear pulse signals for monitoring respiratory frequency variations and faint heartbeat signals (Figure b). Furthermore, an ionic textile-based flexible capacitive pressure sensor was developed by weaving ionic liquid-infused hollow-porous fibers into textiles, forming an ionic fabric dielectric medium. Test results demonstrated stable baseline waveforms without drift, both at rest and after exercise. This system enables non-contact, all-day cardiovascular and respiratory monitoring, stably distinguishing weak respiratory and cardiac signals at the 0.01 kPa level, and accurately detecting both respiratory and ballistocardiographic (BCG) signals (Figure c).

16.

MXene-based flexible pressure sensors for respiration and heartbeat monitoring. (a) Fabrication process of the nanofiber-reinforced MXene-graphene aerogel-based flexible pressure sensor and its application in respiration and heartbeat monitoring. Reproduced with permission from ref . Copyright 2023 Elsevier B.V. (b) Preparation process of the Au–Cu/MXene/rGO aerogel and its application in respiration and heartbeat monitoring. Reproduced with permission from ref . Copyright 2021 Wiley-VCH Verlag. (c) Physiological signal monitoring system using the ionic textile-based pressure sensor in a seated position and corresponding recorded signals. Reproduced with permission from ref . Copyright 2023 Wiley-VCH Verlag.

In summary, MXene-based flexible pressure sensors, utilizing multiple mechanisms such as piezoresistance and capacitance, exhibit distinctive strengths in dynamic and continuous monitoring of respiration and heartbeat. Their high sensitivity allows clear capture and differentiation of weak pressure and deformation signals caused by respiratory and cardiovascular activities even resolving characteristic peaks in pulse waves, thus providing a rich dataset for in-depth health assessment. Innovative designs, particularly those employing ionic textiles, enable non-invasive and stable detection of weak signals, signifying a transition from passive attachment to seamless integration into daily wear. Future research in this area should advance toward more robust multi-physiological signal decoupling and motion artifact suppression, ensuring reliable separation of heartbeat, respiration, and other independent signals even during physical activity. Additionally, new paradigms for contactless or very low-pressure monitoring should be explored, maximizing wearer comfort by detecting subtler physical field variations. The ultimate goal is to construct closed-loop intelligent health systems that integrate monitoring, diagnosis, and early warning. By deeply integrating high-performance sensors with edge computing and artificial intelligence, such systems could achieve real-time physiological analysis, early detection of abnormal patterns, and proactive risk intervention, ultimately translating personalized healthcare from concept to daily practice.

5.2. Human Motion and Rehabilitation Monitoring

In the field of sports medicine, MXene-based sensors play a significant role in athlete selection, rehabilitation training monitoring, and adaptation to special environments, contributing to enhanced athletic performance and safety. However, such sensors face technical challenges including motion artifacts, sweat interference, and device displacement. Future development will focus on intelligent training systems, novel monitoring paradigms, and applications in competitive sports, promoting further advancement of this technology in motion monitoring. Polymer/MXene-based flexible mechanical sensors show considerable potential in wearable health monitoring. Their core advantages include high sensitivity and fast response, enabling accurate capture of physiological signals. Excellent flexibility and conformability ensure wearing comfort without restricting natural joint movement. Furthermore, they can adaptively adjust sampling rates based on dynamic and static conditions, and their outstanding anti-interference capability and environmental adaptability with resistance of water and sweat allow stable operation in complex environments.

A pressure sensor based on a multi-layer interlocked microstructure of PDMS/CNTs-TPU/MXene can be attached to different locations for monitoring various motions. When placed singly on the throat, it captures subtle laryngeal vibrations for swallowing assessment; on finger joints, it tracks flexion and extension in real time. In a system-integrated configuration, sensors are arranged in an array integrated onto a rubber glove, forming a flexible data glove. This five-channel array synchronously outputs waveform amplitude and timing differences for each finger, accurately recognizing five common gestures with 100 ms response time and stable performance over 2000 cycles (Figure ). This provides low-power, comprehensive human motion monitoring for AR/VR interaction and rehabilitation training. A MXene/rGO piezoresistive sensor fabricated on a flexible substrate has successfully realized real-time monitoring of elbow, finger, knee, neck joint bending, facial micro-expressions, respiration, and pronunciation of the vowel “a”. The green and biodegradable MXene/methyl cellulose flexible pressure sensor was attached to joints such as the finger, elbow, wrist, and knee to monitor macroscopic strain generated by bending at different angles in real time, and recorded the wrist pulse waveform peaks P1, P2, and P3 with a response time of 147 ms. When attached to the cheek and perioral area, it distinguishes facial muscle bulging and exhaled airflow. At the array level, simultaneous multi-finger touch or spatial loading with different weights is mapped in real time as a two-dimensional pressure distribution, achieving tactile imaging with both location and intensity resolution. Finally, integrated with a bluetooth module and a mobile app, both single-point and array data can be wirelessly transmitted to mobile terminals, providing a feasible approach for remote health monitoring, smart rehabilitation, and human–computer interaction.

17.

Polymer/MXene-based flexible pressure sensors for joint motion monitoring. Structural composition of the PDMS/CNTs-TPU/MXene pressure sensor and its application in monitoring joint flexion, walking, and other movements. Reproduced with permission from ref . Copyright 2024 Royal Society of Chemistry.

A MXene-based paper sensor was fabricated using PET films as the upper and lower layers, with a screen-printed interdigitated electrode sensing layer using MXene ink in between. Attached to the back of the hand, it accurately captures current waveforms for mouse single and double-clicks, especially double-clicks produce two consecutive peaks, which outperforming the resolution of traditional capacitive sensors. When detecting exhaled or rubber ball-generated airflow at the cheek, the current increases linearly with flow velocity, capturing non-contact micro-pressure vibrations and extending applications to touchless scenarios. For laryngeal movement monitoring during vocalization, saying “Paper” produces a smooth bimodal pattern, while “MXene” generates a multimodal serrated waveform. These unique signal patterns can assist in vocal cord rehabilitation training and provide a green, scalable paradigm for smart rehabilitation and human–computer interaction. Future integration with AI algorithms could further enhance pattern recognition accuracy.

In summary, polymer/MXene flexible sensors, leveraging high sensitivity, fast response, and excellent flexibility and conformability, have demonstrated broad application potential in human motion and rehabilitation monitoring. Current research has successfully achieved multi-scale, multi-modal motion signal monitoring from macroscopic joint movements to microscopic muscle vibrations, and from gesture recognition to voice capture that has preliminarily explored systematic applications such as data gloves, wearable arrays, and integration with wireless mobile terminals. However, practical deployment still faces challenges including motion artifact suppression, sweat and environmental interference, and long-term wearing stability. Future research should focus on developing smarter, more integrated monitoring systems. By optimizing material structures and deeply integrating algorithms, the robustness and pattern recognition accuracy of sensors in complex physiological environments can be further improved. Concurrently, innovative applications in competitive sports training, remote rehabilitation guidance, and immersive human–computer interaction should be expanded, thereby advancing polymer/MXene flexible sensors from the laboratory toward practical, large-scale utilization.

5.3. E-Skin and Human–Machine Interaction

Flexible tactile sensing technology, particularly e-skin plays an increasingly vital role in health monitoring, virtual reality, intelligent robotics, and multimodal human–machine interaction (HMI). Benefiting from bio-inspired structures and MXene composites, flexible tactile sensors have demonstrated marked improvements in sensitivity, multimodal perception, and interactive intelligence, leading to significant progress in e-skin and HMI applications. For instance, a textile-based pressure-sensing array mimicking the skin’s spiny microstructure employs a two-stage amplification effect. It captures weak physiological signals such as the radial artery pulse, recording a real-time pulse rate of 73 bpm (Figure a). In smart office scenarios, the array distinguishes between single and double clicks and senses pressing intensity, enabling “light press–hard press” dual-level function mapping. Simultaneously, a fatigue-resistant MXene-based aerogel (LSMA) with human-like tactile perception achieves dual-mode pressure and temperature detection. Combined with a convolutional neural network (CNN), it enables multimodal input encryption recognition, enhancing the security of interactive systems. This interactive terminal can also be attached to the throat to recognize speech-related micro-vibrations or placed on the sole to differentiate walking from running frequencies without cameras, forming an integrated material, device, algorithm and system wearable input platform (Figure b,c). Inspired by the architecture of the human somatosensory system, a multilayer composite sensor composed of carbon black (CB)/MXene/silicone rubber (SR) was developed. It offers a broad detection range from micro-vibrations to high pressures, making it suitable for robotic tactile feedback and wearable data gloves as human–machine interfaces. To effectively decouple pressure and temperature signals, Gao et al. adopted a porous PDMS/MXene structure integrated with machine learning. This system achieved multimodal touch recognition and secure input with 100% accuracy in interactive identification tasks. Furthermore, a high-performance pressure-sensing array inspired by the multilevel structure of a rose petal was developed. It enables handwriting trajectory recognition and music rhythm visualization and, combined with a deep learning algorithm, achieves high-precision handwritten digit recognition, offering new possibilities for personalized and intelligent input. In a recent study, Huang et al. constructed a flexible array sensor (P-MX) with a bilayer structure comprising microspines and a hollow porous film. This sensor not only recognizes letter shapes and supports wireless health monitoring but also provides stable grasping pressure feedback for robotic arms, thereby extending the application boundaries of e-skin in smart wearables and robotic interaction (Figure d).

18.

Polymer/MXene-based flexible pressure sensors for e-skin and human-machine interaction. (a) Textile pressure sensor array with skin spinous microstructure for e-skin applications, showing pressure distribution during finger pressing and spatial pressure mapping under different loading weights. Reproduced with permission from ref . Copyright 2024 Wiley-VCH Verlag. (b) Flowchart of input message classification using machine learning algorithms with the LSMA flexible pressure sensor. Reproduced with permission from ref . Copyright 2024 Wiley-VCH Verlag. (c) Schematic diagram of the multi-level encryption protection system based on LSMA sensing array. Reproduced with permission from ref . Copyright 2024 Wiley-VCH Verlag. (d) Different stages of robotic arm grasping a medicine bottle using P-MX sensors in human-machine interaction. Reproduced with permission from ref . Copyright 2025 Wiley-VCH Verlag.

Collectively, these studies highlight three key advancement pathways involving improving sensing performance through bio-inspired structures, expanding information dimensions via multimodal detection, and optimizing interactive recognition through intelligent algorithms. They provide important references for designing next-generation e-skin and HMI systems. Nevertheless, critical challenges remain, including low-power multimodal signal fusion and decoupling, improving performance uniformity and durability across large-area arrays, enhancing interference resistance in complex environments, and optimizing embedded algorithms for lightweight operation. Future research will focus on integrating e-skin with wireless communication, energy management, and active feedback mechanisms to build closed-loop interactive platforms. Additionally, incorporating artificial intelligence for adaptive pattern recognition and self-learning capabilities will help expand applications into high-demand fields such as affective interaction, medical rehabilitation, industrial robotics, and virtual augmented reality.

5.4. Dual-Modal Sensing and Multifunctional Integration

By integrating temperature and humidity sensing modules to construct holistic health monitoring systems, MXene-based sensors combined with other sensor types enable simultaneous monitoring of multiple physiological parameters in the human body. In health monitoring, such systems can not only detect pressure changes but also acquire real-time body temperature data and monitor sweat secretion via humidity sensors, thereby achieving comprehensive health assessment. In sports monitoring, the combination with temperature and humidity sensors allows for more accurate evaluation of exercise intensity and physical state, providing a scientific basis for personalized training guidance.

To elucidate the practical implementation of machine learning in MXene-based sensing systems, Figure illustrates a representative AI workflow architecture. The pipeline initiates with raw analog signal acquisition, followed by analog-to-digital conversion and data preprocessing (e.g., noise filtering and normalization). Subsequently, specific input features-such as signal amplitude, response/relaxation times, and peak-to-peak intervals-are extracted via statistical feature extraction to reduce data dimensionality. To construct a robust predictive model using algorithms like Neural Networks, Support Vector Machines, or Random Forests (as depicted in the ML layer), a substantial dataset size is typically required (e.g., 3000 to 5000 independent sampling cycles), usually partitioned into an 80:20 ratio for training and testing to prevent overfitting. Finally, the reliability of the AI decision-making engine is rigorously evaluated using standard validation metrics, primarily including the overall classification accuracy (often targeting >95%), precision, recall, and the confusion matrix. This systematic workflow demonstrates how raw physical stimuli are transformed into intelligent, real-time analytical outputs.

19.

Comprehensive AI workflow for the ML-enabled MXene sensing system.

5.4.1. Pressure–Humidity Integration

Dual-modal sensing technology demonstrates significant application potential in health monitoring and environmental perception. By integrating multiple sensing functions, these sensors can accurately monitor human physiological signals and are widely applicable in motion monitoring, health management, and smart wearable devices. Dual-modal sensors provide an innovative solution for multidimensional physiological monitoring by leveraging two decoupled sensing mechanisms including a positive resistance response to pressure with millisecond-level dynamics, and a negative resistance response to humidity characterized by second-level slow variations.

In medical monitoring, a sodium carboxymethyl cellulose/conductive polyaniline/MXene dual-modal sensor, utilizing hydrogen bonding and electrostatic interactions, has been successfully applied in closed-loop respiratory function analysis. The pressure modality analyzes respiratory airflow frequency changes in real time, while the humidity modality quantifies exhaled tidal volume through the resistance decrease slope. Additionally, a humidity drop threshold enables early warning of apnea events, significantly improving the management of chronic respiratory diseases (Figure a). Extending to excretion monitoring, the sensor constructs a urine volume–resistance linear model via the humidity signal, while the pressure signal effectively distinguishes urine impact from limb movement interference, addressing the common false-alarm issue in traditional wetness sensors. In diabetic patients, monitoring skin humidity, especially changes in foot moisture, can effectively prevent skin infections caused by eczema.

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Polymer/MXene-based flexible pressure sensors for pressure-humidity integration. (a) Schematic diagram of the sodium carboxymethyl cellulose/conductive polyaniline/MXene dual-modal sensor integrated in a smart diaper system. Reproduced with permission from ref . Copyright 2025 Elsevier B.V. (b) Sweat monitoring during various human movements using the MXene-based multifunctional wearable integrated pressure-humidity sensor. Reproduced with permission from ref . Copyright 2025 Elsevier B.V. (c) Humidity variation in respiratory monitoring using the electronic textile-driven multifunctional flexible sensor. Reproduced with permission from ref . Copyright 2024 IOP Publishing. (d) Overall structural design schematic of the electronic textile-driven multifunctional sensor and its sensing patch for humidity monitoring on the arm. Reproduced with permission from ref . Copyright 2024 IOP Publishing.

Furthermore, dual-modal sensing technology has evolved from early pressure and humidity monitoring to integrated sensing platforms with multiple functions. For example, an integrated electronic textile sensing platform based on MXene-modified nonwoven fabric combines pressure, humidity, and temperature sensing capabilities. The pressure sensor in this platform achieves a sensitivity of 1529.1 kPa^–1 (two-electrode configuration, active area: 0.2 cm², MXene loading: ∼0.4 mg/cm²), and the humidity sensor can monitor skin surface humidity changes in real time through clothing (Figure b). Such an integrated system can monitor pressure changes in the joints of elderly individuals, helping prevent joint pain and fractures, and is particularly suitable for bedridden seniors. Zhao et al. proposed an electronic textile-driven multifunctional flexible sensing platform incorporating MXene-modified nonwoven fabric and thermochromic liquid crystal technology, enabling pressure, humidity, and temperature tri-modal sensing. The temperature sensor, based on thermochromic liquid crystals, can be integrated into building materials or clothing to monitor temperature variations, with broad applicability in temperature monitoring, joint pressure assessment, and environmental humidity management (Figure c,d).

In summary, polymer/MXene dual-modal and multifunctional integrated sensors, by combining pressure, humidity, and even temperature sensing capabilities, are advancing flexible sensing from single-parameter detection toward systematic and holistic health monitoring. Current research has achieved polarity-decoupled pressure–humidity detection and expanded into medical scenarios such as respiratory analysis, excretion monitoring, and skin microclimate assessment. Meanwhile, integrated electronic textile platforms incorporating temperature sensing and thermochromic functions show potential in joint protection for the elderly and environmentally adaptive wearables. However, challenges remain regarding anti-interference capability under multi-signal coupling, long-term stability, and wearing comfort. Future efforts should focus on developing highly integrated, self-powered flexible sensing systems with edge intelligence. Through multimodal data fusion and algorithmic optimization, these systems could achieve more accurate and reliable real-time assessment of human physiological status, thereby playing a greater role in personalized healthcare, smart rehabilitation, and daily health management.

5.4.2. Pressure–Temperature Integration

In pressure–temperature integrated sensing systems, the synergistic effect between the thermoelectric properties and piezoresistive effect of MXene serves as the fundamental operating principle. Through microstructure design, such as constructing pyramid arrays, changes in carrier mobility induced by temperature variations and contact area changes under pressure can be simultaneously enhanced, thereby improving sensor sensitivity to these two physical quantities. For instance, a highly elastic, conductive, and thermally insulating 3D structured CS@PDMS foam-based multifunctional tactile sensor maintains stable and reproducible responses to temperature changes even after 100 cycles. By comparison, Wang et al. developed an MXene/TPU nanofiber-based integrated sensing system demonstrating significantly enhanced durability: the pressure sensor exhibited no clear decrease in response current after 10,000 continuous loading/unloading cycles at 1 kPa, while the temperature sensor showed negligible resistance fluctuations after 30 cycles of switching between 25 °C and 50 °C. The signal decoupling mechanism relies on the pressure-independent energy band structure of MXene, ensuring that the voltage signals generated by thermal stimuli and the resistance signals produced by pressure stimuli do not interfere with each other, enabling high-precision, crosstalk-free dual-parameter sensing. Huang et al. developed a multimodal sensing composite hydrogel sensor capable of real-time human joint motion monitoring, which also functions as a magnetically and thermally controlled switch to detect magnetic fields and body surface temperature. This sensor not only detects pressure changes but also responds to magnetic field variations and temperature fluctuations. When the wearable device contacts the human body, the sensor activates relevant functions based on skin temperature and triggers smart device responses according to magnetic field changes.

To further enhance practicality and reliability, a dual-mode pressure–temperature sensing system was integrated into a wearable wristband for real-time monitoring of the wearer’s pulse and body temperature. This system operates stably over extended periods and is powered continuously by an integrated zinc-air battery. Its breathability and water resistance ensure long-term comfortable wear, making it particularly suitable for applications requiring prolonged health data monitoring, with considerable potential in this field (Figure a). Another application involves integrating a MXene/PI foam sensor into smart firefighter garments to simultaneously detect temperature and pressure changes, ensuring safety in extreme environments (Figure b). This sensor exhibits excellent flame-retardant properties and, combined with deep learning algorithms, enables accurate identification of object weight and temperature in smart gloves, providing real-time health monitoring and emergency response capabilities for firefighters.

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Polymer/MXene-based flexible pressure sensors for pressure–temperature integration. (a) Digital images and corresponding test curves obtained during different activities of sitting, running, and walking using the integrated dual-function pressure–temperature sensing system for continuous long-term physiological signal monitoring. Reproduced with permission from ref . Copyright 2024 Springer Nature. (b) Voltage response of the dual-mode temperature-pressure polymer/MXene sensor when approaching and withdrawing from a flame. Reproduced with permission from ref . Copyright 2025 American Chemical Society.

In summary, polymer/MXene pressure–temperature integrated sensors successfully achieve highly sensitive, low-crosstalk simultaneous perception of dual physical quantities by skillfully leveraging MXene’s thermoelectric and piezoresistive properties, combined with microstructure design and signal decoupling strategies. They demonstrate significant application value in wearable health monitoring and intelligent protection. Current research has not only realized long-term stable monitoring of physiological parameters such as pulse and body temperature but also enabled real-time temperature-pressure perception and function triggering in extreme environments like firefighter gear, highlighting excellent environmental adaptability and functional integration potential. However, challenges remain regarding long-term stability in complex real-world scenarios, accurate decoupling capability under multi-physical coupling, and system power management. Future research should focus on developing sensing structures with higher signal-to-noise ratios, self-powered integrated systems, and intelligent analysis modules deeply integrated with AI algorithms to further enhance their practicality and reliability in personalized healthcare, occupational safety protection, and the intelligent Internet of Things.

6. Conclusion and Perspectives

Looking forward, the commercialization and widespread adoption of polymer/MXene flexible pressure sensors will depend critically on advances in manufacturing scalability and technological integration (Figure ). On the manufacturing front, transitioning from lab-scale fabrication to industrial production requires the development of roll-to-roll processing, inkjet printing, and automated assembly techniques that ensure batch-to-batch consistency while minimizing costs. Environmentally friendly synthesis routes for MXene that address oxidation stability and enable precise control over flake dimensions will be essential for reliable device performance. Emerging 3D and 4D printing technologies offer unprecedented opportunities for programmable, customizable sensor architectures with spatially graded properties.

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Roadmap for the future development of MXene-based flexible sensors.

Technologically, the field is evolving toward self-powered, multimodal sensing platforms. Integration with triboelectric nanogenerators and micro-supercapacitors can eliminate external power sources, while multifunctional designs capable of simultaneously detecting pressure, temperature, humidity, and biochemical signals will enable comprehensive health assessment. The implementation of AI and machine learning algorithms is transforming raw sensor data into actionable insights-enabling real-time signal decoupling, adaptive calibration, and pattern recognition for applications ranging from fall detection to disease diagnosis. Wireless, flexible hybrid electronics will facilitate seamless integration with IoT platforms, supporting remote patient monitoring and cloud-based health analytics.

These advances will unlock emerging applications in digital twin frameworks for personalized healthcare, soft robotics with human-like tactile perception, and augmented/virtual reality interfaces that deliver immersive user experiences. By addressing manufacturing challenges and embracing technological convergence, polymer/MXene composite sensors are poised to transition from laboratory prototypes to indispensable components of next-generation smart systems.

The authors declare no competing financial interest.