Recent Progress on Dynamically Tunable Multispectral Stealth Materials

ABSTRACT

The demand for multi‐spectral dynamic stealth technology in complex electromagnetic environments has spurred intensive research into dynamically tunable materials. It is achieved through real‐time modulation of the optical, thermal or electromagnetic properties in the visible, infrared, and radar bands. In this review, recent advances in dynamically tunable materials are summarized and discussed in terms of electrical, thermal, and optical modulation mechanisms. The review further highlights structure‐level design strategies, including metamaterials and metasurfaces for multispectral dynamic modulation. Finally, future perspectives are provided on artificial intelligence (AI)‐assisted design to propel stealth technology toward leapfrog advancement.

This review thoroughly examines recent advancements in dynamically tunable materials for stealth technology. By enabling dynamic and reversible modulation of optical, radiative, and electromagnetic responses under electric fields, thermal stimuli, and optical stimuli, these materials effectively compensate for the adaptability limitations of conventional static stealth approaches.

1. Introduction

Electromagnetic waves (EMWS) serve as a crucial core support in fields such as communications, radar, and medicine, significantly driving technological development and social progress. However, their potential for electromagnetic attack poses a major security challenge to defense systems [1, 2, 3, 4]. The emergence of stealth technology becomes a key research frontier [5]. Nevertheless, a critical challenge persists: single‐band stealth solutions are inherently limited when confronting the sophisticated multi‐spectral detection capabilities [6, 7]. To overcome this limitation, the field is moving towards integrated multi‐spectral stealth, such as combined radar‐infrared, infrared‐visible, and visible‐infrared‐radar systems [8, 9, 10]. But stealth mechanisms are fundamentally distinct across different bands (Figure 1). For example, visible stealth lies in matching the target's chromaticity and brightness to the background, a concept similar to the camouflage principle of chameleons [11]. The infrared stealth lies primarily between 3 and 14 µm. In accordance with the Stefan–Boltzmann law, the total radiant exitance of an object is proportional to the product of its emissivity and the fourth power of its absolute temperature [12, 13]. Therefore, effective infrared stealth relies on adaptive control of emissivity and surface temperature to achieve radiation characteristics that match the surrounding background. Infrared emissivity reduction can be achieved through multiple strategies, including intrinsically low‐emissivity materials such as polished metals. Surface engineering with functional coatings, such as metallic oxides (e.g., SiO₂ and Al₂O₃) and nanocomposite films, as well as multilayer structures (e.g., metal–dielectric multilayers and metal–nitride–dielectric stacks), enables effective emissivity modulation [14, 15, 16, 17]. Metasurfaces design further regulates infrared reflection and scattering, allowing enhanced control of infrared radiation [18, 19, 20]. The radar stealth frequency range is primarily 2–18 GHz. Radar stealth technology is achieved through the utilization of materials capable of absorbing or scattering radar waves, thereby reducing the target's radar cross‐section (RCS) and minimizing its detectability [21]. Consequently, the stealth technologies discussed above impose different requirements: visible stealth materials must exhibit excellent camouflage properties, radar stealth materials require high microwave absorption (MA), and infrared stealth materials demand low infrared emissivity.

FIGURE 1.

Application scenarios of visible stealth, infrared stealth, and radar stealth.

In addition, conventional stealth technologies rely on fixed material properties to achieve stealth, which exhibit limitations such as poor environmental adaptability and limited functionality [22]. The static nature of conventional stealth materials, defined by their fixed parameters, hampers their adaptability to dynamic environmental changes such as diurnal temperature swings and varying background radiation. This often leads to thermal signature mismatches and detection [23, 24]. Moreover, their design, typically optimized for a single band, is fundamentally limited against multi‐spectral detection. Integrating multiple functional layers to broaden spectral coverage inevitably increases weight and volume [25, 26]. As a form of passive defense, static technology has gradually become insufficient to meet the flexible demands of the future due to its lack of intelligent responsiveness [27]. Dynamic stealth technology has arisen as a critical response to these challenges. Dynamic stealth technology realizes real‐time adjustability through smart materials or specific structures and becomes a hot research topic in the field of stealth in the future [28, 29]. It breaks free from the limitations of traditional single‐band, fixed structures. This technology can not only collaboratively regulate electromagnetic radiation across multiple bands but also achieve ‘electromagnetic camouflage’ in complex environments [30].

In recent years, multispectral dynamic stealth technology has made breakthrough progress in material innovation, regulation mechanisms, and system integration. For example, metamaterials and metasurfaces enable rapid switching of electromagnetic parameters for operation in multiple bands through tunable designs [31, 32, 33, 34]. The introduction of functional materials such as phase change materials and graphene provides an efficient response medium for dynamic regulation. However, there are many challenges in the design and implementation of multispectral‐compatible dynamic stealth materials, such as inherent conflicts in physical mechanisms, limitations and integration difficulties of material systems, and issues with large‐scale fabrication. Moreover, existing research still lacks in‐depth analysis and systematic review of multi‐band collaborative mechanisms. This review aims to elucidate the intrinsic relationships between the composition, structure, and modulation mechanisms in dynamically tunable stealth materials in order to guide the future development of this field. The fundamental principles and properties of dynamically tunable stealth materials and artificial electromagnetic structures are introduced. This is followed by a systematic summary of recent advances in multispectral‐compatible dynamic stealth, encompassing radar‐infrared, infrared‐visible, and radar‐infrared‐visible spectral combinations. Finally, the review concludes with an in‐depth analysis of the major challenges in the field and an outlook on future research directions and emerging trends.

2. Principles and Properties of Dynamically Tunable Materials

The increasing diversity of stimuli‐responsive materials and artificial electromagnetic structures, as summarized in Figure 2, is driving the development of intelligent and adaptive stealth technologies [35, 36, 37]. In this context, environmental adaptability represents a central objective of dynamic stealth, which is mainly achieved through two complementary routes. At the material level, external stimuli such as electricity, heat, and light enable reversible modulation of optical, thermal, or electromagnetic properties. At the structural level, artificial electromagnetic structures manipulate wave–matter interactions by regulating reflection, absorption, scattering, and emission. Based on this classification, this section first discusses electrical, thermal, and light‐triggered regulation mechanisms, followed by artificial electromagnetic structures for adaptive stealth [38, 39].

FIGURE 2.

Classification of dynamically tunable multispectral stealth materials and structures. The liquid crystal is reproduced with permission [35]. Copyright 2024, Elsevier. The metamaterials are reproduced with permission [36]. Copyright 2018, Wiley‐VCH. The metasurfaces are reproduced with permission [37]. Copyright 2020, Elsevier.

2.1. Stimuli‐Responsive Functional Materials for Adaptive Stealth

2.1.1. Electrical Modulation of Optical and Radar Responses

An external electric field can alter charge carrier density and ion mobility in certain materials, which in turn may trigger microstructural evolution, including molecular reorientation and phase transitions [40]. These physical processes modulate the material's optoelectronic parameters, such as refractive index, conductivity, absorptivity, and light scattering properties. This modulation thereby achieves dynamic matching or phase‐cancellation interference between the optical response of the target object and the background environment within a specific spatial region. In short, electrical modulation refers to the use of an electric field to control the optoelectronic properties of a material. Prominent examples include electrochromic materials, liquid crystals, ferroelectric materials, and semiconductors [41, 42].

Over the past decades, electrochromic (EC) materials have garnered extensive attention from researchers due to their facile control, rapid response, and diverse color‐changing material systems. These materials are driven through electrical control [43]. They have shown significant application potential in fields such as display devices, electronic information storage devices, and smart windows [44, 45, 46]. Its application in advanced areas such as intelligent stealth and dynamic camouflage demonstrates significant value. The core mechanism relies on the application of an electric field or current to alter the material's electronic structure, thereby enabling dynamic modulation of its infrared emissivity or electromagnetic wave reflectivity. Principal electrochromic materials encompass small organic molecules, conductive polymers, metal complexes, metal oxides, plasmonic nanocrystals, and other emerging systems [47, 48, 49]. Early electrochromic thermal control devices featured a five‐layer thin‐film structure, comprising a reflective electrode (RE), an ion‐storage layer (IS), an ion‐conductor layer (IC), an electrochromic layer (EC), and a transparent electrode (TE) in Figure 3a. Among electrochromic metal oxides, tungsten trioxide (WO₃) is one of the most representative materials. Zhang et al. fabricated an all‐solid‐state WO₃‐based electroluminescent device via the magnetron sputtering process, as illustrated in Figure 3b [50]. The five‐layer structure consists of a crystalline‐amorphous composite WO₃ electrochromic emissivity layer, a LiTaO₃ electrolyte layer, a NiO ion‐storage layer, and an ITO electrode. The device exhibited an emissivity modulation ability (Δε) of 0.37. Under thermal imaging, the device demonstrated reversible switching between hot and cold states, exhibiting excellent dynamic infrared camouflage performance.

FIGURE 3.

(a) Electrochromic thermal control device. (b) Schematic of ECD structure. Reproduced with permission [50]. Copyright 2019, Elsevier.

Compared with inorganic materials, organic electrochromic materials offer distinct advantages, including faster response times, richer color variations, and higher coloration efficiency. These advantages make them promising candidates for adaptive camouflage applications [51]. Conductive polymers are regarded as promising candidates not only for their straightforward synthesis and low cost, but also for their remarkably broad color tunability across most of the visible spectrum. In the field of electro‐emissive polymers, while the exploration of polypyrrole, polyacetylene, and polythiophene has been limited due to their poor cycling stability. But polyaniline and its derivatives have remained a central research focus [52].

To address the limitations of current devices, Zhang et al. proposed a novel strategy. They developed a synergistic architecture by monolithically integrating an electrochromic device with a metamaterial in Figure 4a,b, providing a key structural basis for advanced multispectral dynamic camouflage [53]. The multispectral‐compatible layer consists of a laser‐etched FSS electrode and a TPA‐functionalized, star‐shaped polyaniline. As shown in Figure 4c,d, the ECD exhibited efficient electromagnetic wave transmission in the 10.2–13.9 GHz band, with an insertion loss below 3 dB. The transmission rate exceeded 86% at 11.92 GHz, significantly reducing the radar reflection efficiency of the target. By applying a voltage ranging from −1.6 to 0.6 V, the device can reversibly switch its color between deep jungle green and desert sand yellow, meeting the requirements for dynamic visible‐light camouflage. A large emissivity dynamic range was achieved by this design in the 3–5 µm and 8–14 µm bands, with modulation amplitudes (Δε) of 0.61 and 0.73, respectively. Furthermore, thermal imaging confirmed the design's capability to mimic variations in infrared radiation. The MS‐ECD thereby achieves multispectral modulation across visible, infrared, and microwave bands, providing a new direction for next‐generation intelligent stealth technology (Figure 4i,h).

FIGURE 4.

(a) Fabrication of TPA/ANI copolymer thin film (MS‐EC and MS‐IS layers) and schematic representation of MS‐ECD structure and its operating states. (b) Structure of the periodic unit. (c) Schematic of the free‐space method. (d) Matching of MS‐ECD simulation results to test results. (e,f) Voltage and visible light–near‐infrared color relationship. (g,h) TIR emissivity. (g–j) Thermal imaging of MS‐ECD. Reproduced with permission [53]. Copyright 2024, Elsevier.

Owing to their unique combination of liquid‐like fluidity and crystalline orientational order, liquid crystals are a class of soft materials that are highly sensitive to external stimuli. Under an applied electric field, liquid crystal molecules can undergo reversible reorientation, enabling dynamic modulation of optical properties such as refractive index, transmittance, light scattering, and structural color [42]. Based on their phase behavior, liquid crystals are generally classified into thermotropic and lyotropic systems. Compared with lyotropic liquid crystals, which primarily rely on changes in solvent concentration to induce phase transitions, thermotropic liquid crystals can exhibit rapid and reversible optical responses under thermal or electric stimuli. Among them, blue phase liquid crystals (BPLCs), owing to their ultrafast response characteristics, show significant advantages as a representative system within thermotropic liquid crystals. MXenes, owing to their high electrical conductivity, broadband light absorption, efficient electrothermal conversion, and low infrared emissivity, have been introduced as multifunctional layers in BPLC‐based electrochromic flexible films. Inspired by chameleons, Zhang et al. proposed the idea of chemically integrating BPLC‐based electrochromic 3D soft photonic crystals with MXene [54]. They successfully fabricated electrochromic flexible films (Figure 5a,b). The black MXene film played three critical roles in this research. First, it significantly enhanced the brightness and contrast of the structural color. Second, it acted as a high‐performance Joule heater that derived the 3D soft photonic crystal to achieve an excellent electrochromic response. Thirdly, it served as a flexible surface material with low infrared emissivity. Thermal imaging results showed a markedly lower apparent temperature of only 25°C when the MXene layer was oriented outward, far below the actual temperature of concealed objects like the human body. This property enables precise mimicry of the ambient thermal field, thus effectively evading identification by infrared detectors. The structural color of the blue‐phase liquid crystal can be reversibly switched by an electric field between bright and black across the 400–700 nm visible range, reverting to its original state upon field removal. It should be noted that the current system only achieves dynamic modulation within the visible spectrum. In real‐world battlefield environments or complex scenarios, stealth technologies require not only multispectral compatibility but also environmental adaptability, rapid response capability, low power consumption, and long‐term durability. Future efforts could focus on drawing inspiration from complex biological systems and employing electro‐optical multimodal materials, such as graphene and black phosphorus, to achieve multispectral dynamic compatible stealth.

FIGURE 5.

(a) Preparation diagram. (b) Schematic of fabricating the free‐standing electrochromic flexible film. (c–e) POM images and photographs (insert) of blue, green, and red MXene‐integrated 3D soft photonic crystals. Reproduced with permission [54]. Copyright 2022, Wiley‐VCH.

Beyond electrochromic and liquid‐crystal materials, carrier‐density‐modulated conductive materials, such as graphene, MXenes, and transparent conductive oxides, provide another route for electrical modulation [55]. In these systems, the applied voltage regulates carrier concentration, Fermi level, electrical conductivity, or complex permittivity through electrochemical doping or ion intercalation. Such modulation can alter infrared absorption, thermal emissivity, plasmonic resonance, impedance matching, and microwave electromagnetic loss. For example, voltage‐driven ion intercalation in multilayer graphene can shift the Fermi level and suppress infrared emission, enabling electrically tunable infrared camouflage. Graphene represents a prototypical platform for this mechanism. Salihoglu et al. fabricated a flexible active thermal surface composed of a multilayer graphene electrode, an ionic‐liquid‐filled porous polyethylene membrane, and a back gold electrode [56]. Upon voltage application, ions from the ionic liquid were intercalated into the interlayer spaces of multilayer graphene, which increased the carrier density and shifted the Fermi level. This electronic modulation suppressed infrared absorption and thermal emission, reducing the emissivity of graphene to 0.33 under an applied voltage. This work demonstrates that graphene‐based conductive materials can serve as electrically tunable infrared‐emissivity platforms for dynamic stealth applications. MXenes, particularly Ti₃C₂T_x demonstrate distinctive spectrally selective radiation behavior. These materials exhibit robust optical absorption across the visible (Vis) and near‐infrared (NIR) solar spectra, whereas their infrared absorption and thermal emittance are significantly suppressed in the mid‐infrared (MIR) to long‐wave infrared (LWIR) regimes due to a pronounced infrared reflection effect [55]. This characteristic low infrared emittance primarily originates from the intrinsic metallic conductivity and the free‐electron polarization response mechanism inherent to MXene films. Furthermore, the spectral radiation properties can be precisely modulated by tailoring the chemical composition, surface functional groups (terminations), orientation of the 2D nanosheets, and the microscopic morphology of the thin films. These exceptional attributes render MXenes highly promising for use as infrared modulation layers in multispectral stealth materials, enabling a hierarchical functional design that integrates robust infrared suppression with effective microwave attenuation [57].

2.1.2. Thermal Modulation of Optical and Radiative Responses

Thermal modulation is defined as the temperature‐driven adjustment of a material's infrared radiative properties, especially emissivity and apparent radiative temperature [58]. This process is usually enabled by reversible thermally induced changes in phase structure, lattice arrangement, carrier distribution, or optical conductivity. By altering the emission, reflection, or absorption of infrared radiation, thermally tunable materials can reduce the thermal contrast between a target and its background, thereby achieving dynamic infrared camouflage. Due to their excellent reversibility, phase change materials have found widespread application in fields such as infrared stealth. Representative phase change materials encompass paraffin waxes, fatty acids, and VO₂. Vanadium dioxide (VO₂), a prototypical phase‐change metal oxide, undergoes a reversible phase transition at approximately 68°C [59]. This transition is from a low‐temperature monoclinic structure (VO₂ (M)), which is insulating, to a high‐temperature tetragonal rutile structure (VO₂ (R)), which is metallic. VO₂ in its bare state is susceptible to oxidation when exposed to temperature, air, and moisture [60]. This synergistic erosion leads to a gradual degradation of its thermochromic performance. To address this issue, Wu et al. developed a strategy based on atomic layer deposition (ALD). They successfully fabricated VO₂@Al₂O₃ core‐shell particles using this technique [61]. By controlling the number of ALD cycles, the thickness of the Al‐O shell can be precisely tuned. The core‐shell particles exhibited excellent infrared tuning performance, with emissivity modulation amplitudes (Δε) reaching 0.35 and 0.37 in the mid‐wave and LWIR regions, respectively. Notably, its infrared radiance exhibited a decreasing trend with rising temperature in Figure 6d,e. This decrease enabled the maintenance of a minimal radiance difference between the target and the background, thereby ensuring stable stealth performance.

FIGURE 6.

(a) Schematic of phase evolution between monoclinic VO₂ and tetragonal rutile VO₂. Reproduced with permission [60]. Copyright 2017, Royal Society of Chemistry. (b,c) DSC and TG analyses of VO₂ and VO₂ @A‐O core–shell particles. (d,e) Midwave infrared range (3–5 µm) and long‐wave infrared range (8–14 µm). (b–e) Reproduced with permission [61]. Copyright 2025, American Chemical Society.

However, such inorganic phase‐change materials (PCMs) generally suffer from limitations, including a narrow spectral tuning window, slow response speed, limited tunability, and substrate rigidity. In contrast, organic PCMs, such as paraffin wax, stearic acid, and polyethylene glycol (PEG), have been widely used in thermal management due to their high latent heat and excellent heat storage capacity during the phase transition process. Lu et al. fabricated a KNA/PCM composite film, which is composed of a highly porous and flexible KNA film infiltrated with a phase change material (PCM) such as polyethylene glycol (PEG) [62]. This composite demonstrated an ultralow average transmittance across the broad 3–15 µm wavelength range. The study further proposed that the KNA‐KNA/PCM structure combines excellent thermal insulation with ultralow infrared transmittance, enabling infrared stealth of thermal targets. Although organic PCMs perform well in thermal management, their stealth functionality relies heavily on the enthalpy change during phase transition. Through heat‐induced volume expansion or contraction, thermal expansion materials enable the dynamic modulation of surface roughness, optical structures, or electromagnetic parameters, providing a superior approach for multi‐dimensional dynamic stealth. To this end, Guo et al. employed 4D printing technology to fabricate a pyramid structure model (Figure 7a,b), using a shape‐memory polymer (PLA) as the matrix composite with carbon nanotube (CNTOH), carbonyl iron powder (CIP), and a color‐changing coating [63]. Simulation results indicated that under thermal stimulation, the petal angle of the structure unfolded from 45° to 90°, accompanied by a significant increase in surface roughness. By scattering infrared radiation through diffuse reflection, the structure effectively reduces the thermal contrast between the target and the background (Figure 7c,d).

FIGURE 7.

(a) The process of 3D printing materials. (b) The shape memory programming and recovery process of printed splines and pyramid‐like structures. (c) Photos of changing heat. (d) The temperature changes and behavior of the sample. Reproduced with permission [63]. Copyright 2025, Elsevier.

2.1.3. Light‐Induced Modulation of Optical Responses

In essence, optical modulation refers to the use of light stimuli to tune the optical properties of materials, such as photochromic materials. Photochromic materials are attractive for light‐induced modulation because their absorption, transmittance, and reflectance can be reversibly regulated under light irradiation [64, 65, 66, 67]. They can be broadly classified into organic, inorganic, and organic–inorganic hybrid systems, with mechanisms ranging from molecular isomerization to photoinduced charge transfer and defect‐mediated optical absorption [68, 69, 70]. Organic photochromic molecules usually offer fast response and high molecular designability, whereas inorganic systems generally show better fatigue resistance and environmental stability. Organic–inorganic hybrids further combine the processability of polymer matrices with the stability and functional diversity of inorganic photochromic components. In a representative study, Ling et al. fabricated WO₃/PVA photochromic fibers by a continuous dip‐coating strategy, exhibiting good stability and wash resistance, as illustrated in Figure 8 [71]. Under UV irradiation, the fibers undergo a reversible color change from light yellow to dark blue. The original state can be restored by infrared‐induced thermal stimulation, demonstrating stable optical modulation behavior.

FIGURE 8.

(a) The preparation process of WO₃/PVA photochromic fibers. (b) Color transition of the photochromic fibers upon UV exposure and subsequent infrared heating. Reproduced with permission [71]. Copyright 2018, The Royal Society of Chemistry.

2.2. Artificial Electromagnetic Structures for Adaptive Stealth

Single‐responsive electrochromic, photochromic, or thermochromic materials are limited to reacting to a single physical field and are therefore inadequate for countering multimodal detection. For example, while photochromic materials can modulate optical properties, they cannot address the challenges of electromagnetic reflection in radar detection or thermal radiation in infrared imaging. These materials are also plagued by a narrow modulation range and imprecise control. Consequently, their stimulus‐dependent operation and slow kinetics prevent the real‐time adaptation required for complex scenarios. Artificial electromagnetic structures, including metamaterials and metasurfaces, have attracted extensive attention in adaptive stealth applications. This is mainly attributed to their remarkable capability to flexibly manipulate EMWS through engineered subwavelength architectures. Artificial electromagnetic structures mainly realize dynamic electromagnetic responses through the design of geometric configurations, optimization of periodic arrangements, and regulation of resonant behaviors. By integrating tunable components or active materials, these structures can dynamically manipulate absorption, reflection, scattering, and emission characteristics across multiple electromagnetic bands. The emergence of metamaterials and metasurfaces provides an effective solution to this challenge.

2.2.1. Metamaterials

Metamaterials are artificially engineered materials composed of periodic or quasi‐periodic arrays of subwavelength building blocks, known as “meta‐atoms”, whose effective electromagnetic properties are determined by structural design rather than material composition. Emerging in the late 20th century, they enable precise manipulation of EMWS through rational control of subwavelength resonant structures [72]. By tailoring the geometry and arrangement of meta‐atoms, metamaterials allow effective regulation of permittivity, permeability, and refractive index, leading to unconventional electromagnetic responses. As a result, they enable key phenomena such as negative refraction, subwavelength imaging, and electromagnetic cloaking [73, 74, 75]. In particular, the unique optical properties of metamaterials play a key role in practical stealth technology. By integrating them with functional materials such as thermochromic and electrochromic compounds, dynamic multispectral stealth can be achieved. Qu et al. reported a metamaterial‐based device enabling compatible dynamic stealth for infrared (EC‐IR) and radar frequencies in Figure 9a [76]. The device was designed with a three‐layer composite architecture. By utilizing impedance matching and magnetic resonance, the top‐layer ITO square‐ring metasurface achieved greater than 90% absorption efficiency across the 9.67–16.04 GHz range. The middle layer employed a 2‐mm‐thick ZnS dielectric, which combined low microwave loss (dielectric constant of 8.3) with high infrared transmittance, achieving up to 88.9% transmission in the 8–14 µm infrared band. The CNT top layer exhibited a dynamically tunable infrared emissivity (0.152–0.783) under ±3.5 V bias, serving the dual innovative roles of an electrochromic active layer. Simultaneously, the metamaterial layer provided consistent radar wave absorption, overcoming the long‐standing challenge of synergistically combining dynamic infrared modulation with radar stealth in conventional materials. In line with the shift toward smart materials, Wang et al. designed a mechanically tunable bistable metamaterial (Figure 9d) [77]. By integrating the mechanical deformation of bistable beams with digital coding control, this material achieves dual active and passive reconfiguration of its electromagnetic scattering properties. The integration of bistable beams with metamaterial unit cells enabled a coupled “mechano‐electromagnetic” functionality. This design not only met stealth requirements across different frequency bands but also allowed for continuous tuning of the absorption bandwidth through digital coding.

FIGURE 9.

(a) schematic diagram of preparation processing of the metamaterial. (b) Reflectance and absorptance of the metamaterial. (c) Simulation of electric field and surface current distribution. (a–c) Reproduced with permission [76]. Copyright 2024, Elsevier (d) Schematic diagram of multifunctional metamaterial, surface patterns, and bistable structures. Reproduced with permission [77]. Copyright 2024, Wiley‐VCH.

2.2.2. Metasurfaces

The inherent limitations of metamaterials, such as complex fabrication, large volume, and high insertion loss, have driven the emergence of two‐dimensional (2D) metasurfaces [78, 79]. Metasurfaces enable precise engineering of EMWS at the subwavelength scale, allowing for tailored control over their polarization state, amplitude intensity, and phase distribution. These unique advantages make metasurfaces an ideal technological solution to overcome the limitations of conventional metamaterials, providing an innovative pathway for cutting‐edge fields such as multispectral dynamic stealth. On the one hand, integrating active components into the metasurface structure can provide dynamic tuning of its electromagnetic response, offering an active control pathway for multi‐band adaptation. On the other hand, modulating the physical and chemical properties of the metasurface substrate can also enable dynamic adjustment of its key performance, thereby expanding the diversity of applicable scenarios. Mu et al. designed a spatiotemporally coded stealth metasurface featuring an amplitude‐phase cooperative control system in Figure 10a [80]. Its core operational mechanism relies on the precise control of two integrated PIN diodes, which enables the metasurface unit to switch controllably between radiation and scattering modes. Based on this mode‐switching capability, the metasurface successfully achieved the integrated implementation of both dynamic stealth and radiation functions within the X‐band. This innovative design provides a novel approach for developing integrated radar‐communication‐stealth systems, particularly suitable for advanced platforms such as fighter aircraft and naval vessels that require simultaneous detection and stealth capabilities. From a physical mechanism perspective, this metasurface efficiently induces a scattering phase‐cancellation interference effect by precisely designing the polarization response and phase‐coding logic of its unit cells. The incident electromagnetic wave, after being modulated by the metasurface, interacts with the wave scattered directly from the target itself, creating a phase‐cancellation superposition in the spatial domain. This process significantly reduces the target's RCS, thereby fundamentally enhancing its radar stealth performance and providing fundamental mechanistic support for the application of metasurfaces in multi‐modal stealth. The phase coding pattern of the metasurface can be dynamically optimized in real‐time via a control system, and the spatial power distribution of the electromagnetic wave can be arbitrarily reconfigured. This technological transition from three‐dimensional bulk materials to two‐dimensional planar structures not only inherits the exceptional potential of metamaterials for manipulating physical fields but also achieves performance innovation through dimensional simplification and functional integration. This breakthrough provides a novel solution to the problems inherent in conventional stealth approaches, including bulky structures, significant losses, and limited dynamic response. Nevertheless, the aforementioned design still lacks flexibility, and current research in the field is focusing on achieving tunable performance by manipulating the properties of the metasurface substrate. Yang et al. designed a dual‐tunable graphene metasurface based on a patterned graphene interlayer structure [81]. This metasurface enables dynamic switching from single‐frequency absorption (12–24.8 GHz) to broadband absorption covering 10–25.7 GHz. When a bias voltage is applied to the graphene layer, the absorption amplitude of the metasurface can be dynamically and independently tuned within an average range of −5 to −15 dB. The metasurface not only exhibits excellent optical transparency and flexibility but also allows for precise dynamic modulation of both the reflection amplitude and resonance frequency, demonstrating its multi‐dimensional tunability.

FIGURE 10.

(a) Dual‐mode design of Radiation—Stealth metasurfaces. (b) Spatially coded stealth with dual‐mode radiation. Reproduced with permission [80]. Copyright 2024, Wiley‐VCH.

3. Multi‐Band Compatible Dynamic Stealth

Stealth technology has become a critical component of modern military operations, aimed at concealing detectable signatures of military assets to avoid enemy detection. However, the limited spectral coverage of single‐band stealth systems falls short in countering multi‐spectral detection threats. The development of multi‐spectral compatible stealth, capable of operating across domains such as infrared‐visible, infrared‐radar, and visible‐infrared‐radar, is therefore essential for enhancing the survivability and anti‐detection capability of military platforms. Such integrated stealth solutions provide a more robust and adaptable defense mechanism for advanced military equipment in complex electromagnetic environments.

At present, the mainstream approaches for dynamic multispectral stealth can be categorized as follows. The first approach involves the incorporation of electrically, optically, or thermally controlled chromic materials to modulate optical and electromagnetic parameters and their subsequent integration with other functional materials to create a synergistic mechanism. This integration ultimately facilitates the dynamic control of multispectral signatures. Second, the design of metasurface microstructures enables precise manipulation of the electromagnetic wave phase. Third, the development of fluid‐driven systems provides a pathway for multispectral compatible intelligent stealth. Yang et al. designed a composite system composed of a deformable mechanical color layer, an elastomeric structure, and a channel dielectric layer [82]. The strain generated in the elastomer under fluidic actuation is efficiently transmitted to the mechanical color layer, thereby deforming the nanostructures in a controllable manner. This coupled process allows for the dynamic regulation of the visible reflection wavelength and consequent color switching. Furthermore, the heat‐absorbing property of the fluid enables dynamic infrared stealth by reducing the apparent temperature of the target. Concurrently, the resonant performance for radar wave absorption can be dynamically optimized by tuning the spatial configuration parameters of the high‐permittivity fluid, which paves the way for radar‐band stealth capabilities. Such a fluid‐driven intelligent stealth device therefore represents a platform capable of compatible stealth across the visible, infrared, and radar spectra, while also exhibiting key advantages of a broad modulation range, rapid response speed, and excellent cycling stability. These capabilities collectively enhance military camouflage performance and provide crucial support for multi‐modal stealth applications in complex environments.

3.1. Visible‐Infrared Stealth

Driven by the critical needs of modern stealth strategies and the urgency of evolving combat scenarios in military modernization, the development of compatible stealth materials for visible and infrared bands has become a pressing imperative. To achieve this compatible stealth capability, the material design must fulfill two key requirements. First, the material must achieve high‐efficiency matching with the background's spectral characteristics in the visible band, thus enabling visual camouflage. Secondly, the material should possess appropriate infrared emissivity (ε) characteristics to minimize the radiative difference between the target and the background. Ren et al. proposed a closed‐pore plasmonic stealth (CC‐PS) metastructure via refined micro‐nano design in Figure 11a [83]. This architecture successfully delivered excellent static stealth performance spanning the visible and infrared spectra. It was demonstrated that the emissivity of the material could be effectively tuned by controlling the composition and thickness of the Ti@SiO₂ film, as well as its deposition thickness on the pore‐array surface in Figure 11b,d. Performance tests revealed that the fabricated CC‐PS metamaterial achieved an average reflectance of 16.1% in the visible band, while maintaining a low emissivity of 0.27 within the 8–14 µm infrared atmospheric window. This work confirms that micro‐nanoscale structural design strategies can overcome the limitations imposed by materials' intrinsic properties, thereby offering a new technological pathway for achieving multispectral stealth compatibility.

FIGURE 11.

(a) Design of CC‐PS metamaterials. (b) Emissivity and infrared thermal images of films with different Ti contents. (c) Emissivity and infrared thermal images of films with different thicknesses. (a–c) Reproduced with permission [83]. Copyright 2025, Elsevier. (d) Design schematic of MSDR. (e) Ideal spectrum for color‐thermal camouflage under different device states. (d,e) Reproduced with permission [85]. Copyright 2025, Springer Nature.

Presently, the material is confined to static stealth applications. Nevertheless, the design concept integrating a closed‐pore structure with a plasmonic nanoparticle film provides crucial insights and lays the groundwork for the structural design of future dynamic stealth systems. The implementation of dynamic stealth relies on strategies in material design and structural optimization. Materials with tunable optical responses, such as electrochromics offering low‐voltage operation and low power consumption, enable dynamic spectral control rooted in their inherent material properties. Table 1 systematically compares the optical characteristics, dynamic tunability, and flexibility of typical visible‐infrared stealth materials. Wang et al. developed a broadband electrochromic thermal stealth device centered on an AZO/Ag/AZO electrode [84]. A multicolor V₂O₅ electrochromic film was subsequently fabricated on this electrode via a self‐assembly deposition method. The reversible color change from blue to yellow is achieved by Li⁺ intercalation/deintercalation, which modulates the vanadium ion valence under an applied voltage. The AZO layer ensures good transparency to clearly manifest these color changes, while its impedance matching with the metal layer enables tuning of the visible‐light transmission peak. This work integrates the dynamic modulation capability of electrochromism with a metal‐dielectric based static infrared stealth system. Li et al. designed a multispectral dynamic regulator (MSDR) based on VO₂ in Figure 11d [85]. The device features a top multilayer film with alternating VO₂ and HfO₂ layers, which enables dynamic tuning of its visible color. In the low‐temperature insulating state, VO₂ and HfO₂ exhibit a significant contrast in their refractive indices. This contrast enables the structure to strongly reflect visible light of specific wavelengths, thereby exhibiting distinct colors. A temperature‐induced phase transition to the metallic state sharply reduces the refractive index of VO₂. This change leads to a blue shift in the reflection spectrum, enabling dynamic color switching. The bottom layer is a thick VO₂ film that serves to dynamically regulate thermal infrared radiation, enabling effective tuning of infrared emissivity. HfO₂ as a transparent medium across both the visible and infrared bands, enabling the independent regulation of functionalities in these two spectral regions. The device is therefore capable of independently and simultaneously tuning both its visible color and its infrared emissivity. Moreover, this study introduced a novel design strategy for digital camouflage. Digital camouflage operates by introducing a “neighboring color block algorithm,” which assembles the various colors generatable by the device into pixelated patterns. This method not only achieves color variation but also simulates digital camouflage textures of complex environments like forests and deserts, thereby significantly enhancing both the realism and scene‐adaptive capability of the stealth effect. An ideal future device should integrate both passive and active capabilities. Passive response ensures basic stealth without external intervention, while active control enables adaptation to unexpected scenarios or the execution of specific tactical requirements.

TABLE 1.

Summary of the properties of visible‐infrared stealth materials.

Materials	Visible light performance	Infrared performance		Dynamic	Flexibility	Refs.
CrTiWYAl High‐entropy‐alloy	High absorption (α = 0.870)		3–14µm: ε = 0.069	×	√	[87]
Si/Bi/Si/Cr	Match multiple backgrounds(orange、blue、purple)		3‐5µm: ε = 0.39; 8–14µm: ε = 0.367; 5–8 µm: ε = 0.79	√	√	[88]
AZO/Ag/AZO	Visible light transmittance:>65%; Color switching: blue, dark green, light green, bright yellow		3–14µm: reflectivity>80%	√	×	[84]

In the field of infrared stealth, conventional strategies rely on modulating a material's infrared emissivity to match the radiative signature of the background. In contrast, the approach of temperature regulation demonstrates superior environmental adaptability. Bai et al. designed a composite structure comprising three distinct layers [86]. They innovatively integrated thermal insulation aerogel, phase change material, photothermal/electrothermal materials, and a thermochromic coating into a single platform (Figure 12a). The aerogel layer, composed of MXene and reduced graphene oxide (RGO), features a unique microchannel structure that effectively suppresses heat transfer via conduction, convection, and radiation. Owing to their excellent electrical conductivity, the RGO and MXene components enable surface heating under illumination to match the ambient temperature in Figure 12b–d. Moreover, rapid temperature modulation can be achieved under an applied voltage to interfere with detection systems. The combined thermal insulation from aerogel and heat storage from PCM creates an effective thermal shield. It drives the object's surface temperature to approximate the surroundings, thereby achieving thermal camouflage or “disappearance” in infrared imaging. The photothermal and electrothermal effects of the MXene/RGO component provide the thermal input for the thermochromic layer. This thermal input drives the color transition, enabling dynamic matching to various colored backgrounds. The functional integration of multiple materials offers a novel research path for addressing complex military environments. This integrated approach holds promising application potential in areas such as military thermal camouflage, intelligent thermal management, and smart buildings. Currently, dynamic visible/infrared compatible stealth technology has advanced beyond initial explorations based on single materials or targeted at individual wavebands. The field is now entering a new research phase focused on multi‐band intelligent synergy and system integration. This evolution is driven by sophisticated micro‐nano structural design and the convergence of cross‐disciplinary technologies. Researchers are dedicated to developing intelligent stealth solutions with enhanced environmental adaptability, practical potential, and broad‐spectrum response capabilities.

FIGURE 12.

(a) Schematic illustrating the preparation of an MG/PCM/TCM trilayer composite. (b) Infrared images of the MGP composite and the M1G1 aerogel covering human fingers. (c) Infrared camouflage of a low‐temperature target in a high‐temperature background via electrical heating at 3 V. (d) Infrared disguise presentations of the fake target heated by a battery of 1.5 V. (e) UV−vis−NIR absorption spectra of MXene, RGO, MGP, and the MGPT composite. (f) Temperature−time curves of the MGPT composite under different solar light irradiations. (g) Temperature−time curves of the aerogel layer and the phase change layer under 0.8‐sun. Reproduced with permission [86]. Copyright 2023, American Chemical Society.

3.2. Infrared‐Radar Stealth

Single‐band stealth approaches (infrared or radar) fall short of addressing contemporary military needs. As a result, achieving compatibility between infrared and radar stealth has garnered significant research attention. Essentially, the detection mechanisms for infrared and radar are contradictory. The preparation of composite materials exhibiting superior microwave absorption and low infrared emissivity is enabled by precisely controlling their nanostructure and physical properties. This methodology constitutes a critical strategy for realizing dual‐band infrared‐radar camouflage [89]. To achieve this compatibility, researchers have explored a variety of materials and structures, with representative examples including graphene, polymers, aerogels, and metamaterials. As a classic composite architecture, the core‐shell design enables the orderly integration of materials with disparate functions for precise performance tailoring. Zhang et al. employed a hydrothermal route to successfully prepare the SnO₂@ZnO composite [90]. The material exhibits a minimum reflection loss of −23.51 dB at 9.2 GHz and an effective absorption bandwidth of 3.5 GHz. Simultaneously, it exhibits a tunable emissivity (0.65–0.89) in the mid‐to‐far infrared range, collectively demonstrating favorable radar‐infrared compatible stealth performance. Its excellent performance originates from the improved impedance matching due to the hierarchical structure and enhanced interfacial polarization, as well as the tunable morphology that regulates infrared radiation. Li et al. designed a multi‑scale hierarchical structure incorporating wrinkled MXene and Fe₃O₄@C/PDMS composites [91]. With its high reflectance and low emissivity, wrinkled MXene serves as an infrared shielding layer while allowing microwaves to transmit to the underlying layer. The underlying Fe₃O₄@C/PDMS layer serves as a microwave absorber, effectively attenuating radar signals via magnetic‑dielectric synergistic loss. This structure demonstrates compatible stealth performance with a RCS reduction of −20 dB·m² in the X‑band (8–12 GHz) and an average infrared emissivity of 0.35 in the long‑wave infrared (LWIR, 8–14 µm) band.

The use of thermoelectric devices (TEDs) for surface temperature modulation enables dynamic camouflage. Yuan et al. proposed a thermoelectric metamaterial device (TEMD) that integrates the design philosophy of coding metamaterials with the active temperature‐regulation mechanism of thermoelectric devices (TEDs) [92]. Leveraging the principle of coding metamaterials, basic elements with 0° and 180° reflection phase responses are meticulously designed and arranged in a periodic pattern. It effectively modulates microwave phase characteristics while achieving broadband absorption with reflection loss below –10 dB across the 10–16.1 GHz frequency range. The integration of Bi₂Te₃ thermoelectric pillars and ceramics facilitates dynamic control over surface temperature and emissivity in the 3–14 µm band. The structure exhibits an infrared reflectivity as low as 0.028, effectively suppressing the reflection of environmental thermal signatures. However, these structures only function under static conditions, lacking the capacity for dynamic response and adaptive regulation to changes in the external environment.

Liang et al. proposed a pneumatic actuation‐based multiscale deformation mechanism [93]. This mechanism enables dynamic tuning of the surface morphology, thereby achieving simultaneous compatible stealth in both infrared and radar wavebands. The structural unit is composed of a deformable MXene/elastomer conductor and a dielectric spacer layer with inflatable channels in Figure 13. Upon inflation of the pneumatic unit, the MXene/elastomer composite structure transforms from a flat state into a convex hemispherical morphology. This deformation enhances the electromagnetic response of the material, extending its tunable absorption bandwidth to 2.64–18.0 GHz. The underlying mechanism lies in how the altered geometry modifies the inter‐unit electromagnetic coupling and resonance modes, thereby enabling the dynamic broadband absorption of radar waves in Figure 13a–c. Simultaneously, within the infrared band, the surface of the MXene film undergoes a microscopic transformation. During inflation, its surface wrinkles are stretched into a smooth plane, and this morphological change reduces the scattering and absorption of infrared waves. Additionally, the air‐filled cavity structure formed by inflation possesses low thermal conductivity, which further suppresses radiative heat transfer. By synergistically modulating both the structural morphology and electromagnetic properties through pneumatic deformation, this work achieves dynamic compatible stealth across the infrared and radar wavebands. Compared with electrically driven approaches, pneumatic actuation offers advantages including rapid response, independent and precise multi‐channel control, and relatively low energy consumption. The research focus in future stealth materials is shifting from optimizing single material components toward the co‑design and regulation of multi‑scale macro structures/ macro structures. Future systems could integrate sensors and AI algorithms, enabling the camouflage platform to perceive ambient electromagnetic/thermal signatures in real time. It would then automatically compute and execute the optimal camouflage pattern, achieving genuine “environmentally adaptive stealth.”

FIGURE 13.

(a) Schematic diagram of the structural unit of a deformable wrinkled MXene/elastic conductor and a rigid inflatable base. (b) Multiscale shape deformation and deformation mechanisms of deformable conductors. (c) Mechanism diagram of adaptive radar‐IR compatible camouflage. (a–c) Reproduced with permission [93]. Copyright 2023, Wiley‐VCH. (d) Schematic illustration of the proposed TEMD. (e) Schematic illustration of the proposed TEMD element. (d,e) Reproduced with permission [92]. Copyright 2022, Wiley‐VCH.

3.3. Visible‐Infrared‐Radar Stealth

In response to the complex threat of multispectral detection, researchers have further proposed compatible stealth technologies aiming for broader frequency bands and dynamic tunability. However, this direction still faces significant challenges, with systematic research in this area remaining at an early stage. Two principal design approaches have been pursued in traditional multispectral camouflage research. The first centers on the integration and hybridization of material compositions to achieve multifunctionality. Alternatively, the second strategy employs the spatial construction of layered, multi‐level architectures with distinct functional assignments. For example, Wen et al. employed a vacuum‐assisted filtration process to layer‐by‐layer assemble MXene (Ti₃C₂T_x), black phosphorus (BP), and nickel chains [94]. This fabrication strategy yields a flexible M‐B‐M(Ni) composite film capable of compatible stealth in the visible, infrared, and radar regions of the spectrum. In the infrared band, the film exhibits an emissivity as low as 0.1 (Figure 14b). For the X and Ku bands, it shows an electromagnetic shielding effectiveness exceeding 50 dB, with an absorption contribution of 84.6%, effectively suppressing reflection losses (Figure 14e). In the visible range, its absorption reaches 80% due to the strong light absorption of BP (Figure 14c). This study demonstrates static tri‐band compatible stealth achieved through the synergistic combination of multiple materials. However, this material‐hybridization strategy mainly relies on fixed optical, infrared, and microwave electromagnetic parameters, and therefore offers limited dynamic tunability, especially in the microwave region. Dynamic microwave modulation is critical for radar stealth and electromagnetic reflectivity control. In this context, Han et al. demonstrated a representative example of active microwave regulation based on the electrochemically modulated interaction between MXene thin films and microwaves [95]. Through reversible ion intercalation and de‐intercalation, the interlayer spacing and electrical conductivity of MXene films can be dynamically regulated, enabling continuous modulation of microwave reflection, absorption, and electromagnetic interference shielding effectiveness. This study highlights the potential of MXenes as actively tunable components for adaptive multispectral stealth, although practical deployment still requires further improvements in broadband modulation capability, cycling stability, and environmental durability. Beyond electrochemical modulation, resonant structural design offers another route to control optical and microwave responses.

FIGURE 14.

(a) Schematic diagram of the preparation of the M‐B‐M(Ni) film. (b) Mid‐ and long‐wavelength IR emissivity. (c) EMI SE (SET, SER, SEA) in the X band. (d) Absorption spectra of the films at visible and near‐IR wavelengths. (e) Enlarged absorption spectra of the films at visible wavelengths. Reproduced with permission [94]. Copyright 2023, Wiley‐VCH.

The Fabry–Pérot (F–P) cavity, a classic optical resonant structure, has been utilized in the field of camouflage technology. The Fabry–Pérot (F–P) cavity operates through a distinctive mechanism of “selective resonance,” enabling the precise manipulation of light within specific wavebands. In addition, integrating MXenes with Fabry–Pérot (F–P) cavity structures offers a promising strategy for structural color modulation and visible‐light camouflage. Zhang et al. constructed MXene/SiO₂/Al trilayer films, in which the light‐lossy absorption of MXenes and the thin‐film interference effect of the F‐P cavity were combined to generate vivid and tunable structural colors [96]. By regulating the MXene composition, MXene‐layer thickness, and SiO₂ dielectric‐cavity thickness, this system enables target appearance modulation and provides a potential route toward visible‐light stealth. This strategy also provides new insights into integrating the optical and electromagnetic functionalities of MXenes with the resonant modulation capability of Fabry–Pérot cavities. Yang et al. proposed a multispectral camouflage system employing a Fabry–Pérot (F–P) matching‐loss metasurface. Thermochromic capsule materials are employed in the top camouflage pixel layer (CPL) [97]. Based on thermal variations, this layer can autonomously render pixelated patterns adapted to diverse environments, including forests, oceans, and mountains. This design structurally integrates the top camouflage pixel layer (CPL) with a closed‐pore foam layer. The composite effectively combines spectral modulation with thermal insulation, synergistically achieving efficient infrared thermal camouflage. Functioning as an impedance‐matching layer, the F–P cavity effectively channels microwaves into the underlying absorption layer. The bottom layer consists of a composite material incorporating patterned ITO bilayers, carbonyl iron, and multi‐walled carbon nanotubes, exhibiting both magnetic and dielectric loss characteristics. Through the coupled synergy of F–P cavity regulation and the multi‑layer loss network, dynamic compatible stealth across the visible, infrared, and microwave bands is ultimately achieved. Future stealth materials can be architected using a biomimetic strategy of “independent layer control and systemic integration.”

Yang et al. proposed a multifunctional layered flexible metasurface (MHFM) consisting of an infrared suppression layer (IRSL), a microwave absorbing layer (MAL), an environmental adaptation layer (EAL), and a total reflective sheet (TRS) [98]. TCCS is selected as the main material of EAL to transform between grass‐green and earthy‐yellow colors to adapt to grassland and desert environments and achieve dynamic visible‐light camouflage. ITO is used as the ISPL layer, and the average IR emissivity measured in the IR wavelength range of 3–14 µm is 0.229, which maintains a low IR emissivity and achieves IR camouflage. The MAL achieves multi‐frequency resonance absorption by using different resistors and structure sizes, and the absorption rate is more than 90% at 2.53∼34.56 GHz. This structural design simultaneously realizes low IR emissivity, broadband microwave absorption, and dynamic visible camouflage. The layered and synergistic design provides a new idea for multispectral stealth materials and effectively solves the problem of conflicting demands in different frequency bands.

4. Conclusion and Outlook

This review surveys recent advances in dynamically tunable metamaterials for stealth across visible–infrared, infrared–radar, and visible–infrared–radar spectra bands. We focus on the underlying mechanisms enabled by electric, thermal, and optical field modulation, as well as multi‑physical field synergy. Building on these progresses and representative cases, key conclusions and future research trends are outlined:

1. Dynamically tunable stealth materials can be achieved by selecting electrochromic, photochromic, or thermochromic materials as building blocks, which enable real‐time tuning of properties. However, many reported systems still operate within a limited spectral range, and their practical performance is often constrained by slow response, insufficient cycling stability, limited modulation amplitude, and environmental sensitivity. Future studies should therefore look beyond increasing optical or thermal contrast and systematically evaluate response speed, reversibility, energy consumption, and long‐term durability under realistic operating conditions.

2. Modern stealth design is undergoing a shift—from the pursuit of intrinsic absorbing materials to the construction of integrated, multifunctional layered architectures. This shift is exemplified by infrared and multispectral stealth, which employs a stratified functional strategy. Specifically, this architecture comprises three distinct functional layers. The outermost layer consists of active materials with low infrared emissivity, such as electrochromic polymers or liquid crystals, which are engineered to dynamically modulate both optical color and infrared emissivity. The middle layer incorporates low‐thermal‐conductivity materials like aerogels, serving as a thermal barrier to attenuate infrared radiation from the internal platform. The innermost layer utilizes thermal management materials, including PCMs, to efficiently absorb and homogenize residual heat. The collective functionality of this multi‐layer structure, achieved through the synergy of its components, enables adaptive, multi‐band compatible stealth.

3. Integrating two‐dimensional materials, such as graphene and transition metal dichalcogenides, as active components into metasurfaces. This approach enables programmable control over the electromagnetic phase and amplitude of metasurfaces. This strategy is expected to enable broadband and tunable dynamic stealth. However, the field remains at an early stage, and current metasurface‐based dynamic stealth systems still face several challenges. First, the fabrication of tunable metasurfaces usually relies on micro‐ and nanofabrication techniques, making large‐area and low‐cost manufacturing difficult. Second, their active modulation range is often narrow, and the modulation depth tends to decrease sharply at higher frequencies. Third, electrical, thermal, or optical actuation generally requires the integration of power supplies or light sources, which is difficult to reconcile with lightweight and low‐power stealth platforms. Finally, under practical conditions involving temperature fluctuations, mechanical deformation, or electromagnetic interference, the resonant structures of metasurfaces may become detuned, leading to degraded stealth performance. More importantly, many reported studies remain limited to device‐level demonstrations at fixed frequencies or under ideal polarization conditions, with insufficient system‐level validation under dynamic, multi‐angle, and broadband detection scenarios. Future research should therefore move from isolated evaluation of material or structural performance toward application‐oriented system‐level design.

The synergistic interactions among multiple physical fields result in significant energy conversion losses, hindering the deep integration of multi‑band performance. Furthermore, achieving a balance between response speed and stability in certain designs remains difficult, which limits their practical applications. Additionally, the complexity of the fabrication process and the associated high costs pose barriers to large‑scale implementation. Moving forward, research on multi‑spectral dynamic stealth technology should prioritize breakthroughs in the following areas:

1. We must depart from conventional design paradigms and propose more innovative strategies. In the future, structural design may shift from homogeneous modular approaches to heterogeneous modular strategies. For instance, in aircraft design, a “heterogeneous” configuration can be implemented by tailoring different regions according to their specific radar exposure angles and infrared hot‐spot distributions. This approach moves beyond focusing solely on singular material structures, directing greater attention toward the integrated co‐design of “structure‐material‐device‐circuit” systems.

2. Combine materials with artificial algorithms to realize more accurate intelligent regulation. In the future, molecular dynamics, machine learning, and data‐driven approaches could be integrated to establish a materials genome engineering database for dynamic stealth applications. Such a database could be specifically employed to simulate multi‐field coupling responses and multiband electromagnetic interactions, thereby reducing experimental trial‐and‐error costs and predicting how microstructural evolution under specific external stimuli influences macroscopic frequency‐dependent properties. Beyond materials screening and performance prediction, artificial intelligence also demonstrates significant potential in metastructure and metasurface design. For example, generative adversarial networks (GANs) and variational autoencoders (VAEs) can enable the inverse design of metasurface units with targeted electromagnetic responses. Reinforcement learning algorithms can further optimize the spatial arrangement and coding sequences of metastructures, thereby achieving precise regulation of scattering, absorption, and reflection behaviors. In addition, artificial intelligence can also be applied to the design of cross‐scale heterogeneous structures, providing important guidance for the experimental development of dynamic stealth devices.

3. Explore preparation technologies to reduce production costs and improve production efficiency. Currently, the predominant use of silicon‐based substrates in device fabrication substantially limits their applicability. Replacing silicon with more diverse flexible substrates presents a viable solution. Furthermore, realizing patterned dynamic functional materials necessitates the fabrication of large‐area nanoimprint molds, requiring a breakthrough in nanoimprint lithography technology. To achieve complex three‐dimensional micro‐nano structures and the selective deposition and removal of heterogeneous materials, integration with techniques such as inkjet printing and aerosol jet printing can be employed.

With the increased requirements of militarization, more emphasis will be placed on the research of multi‐spectrum dynamic stealth in the future. It is hoped that continuous innovation in materials, structures, and modulation methods will lead to more strategies for multi‐band dynamic stealth in the future, bringing new changes to military security, intelligent equipment, and other fields.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.