Recent Advances in Triboelectric Materials for Active Health Applications

Abstract

Triboelectric materials can convert irregular mechanical stimuli from human motion or environmental sources into high surface charge densities and instantaneous electrical outputs. Their intrinsic properties, such as flexibility, stretchability, chemical tunability, and compatibility with diverse substrates, play a critical role in determining the efficiency and reliability of triboelectric devices. In the context of active health, triboelectric materials not only serve as the core functional layers for self-powered sensing but also enable real-time physiological monitoring, motion tracking, and human–machine interaction by directly transducing biomechanical signals into electrical information. Soft triboelectric sensors exhibit high sensitivity, wide operational ranges, excellent biocompatibility, and wearability, making them highly promising for active health monitoring applications. Despite these advantages, challenges remain in enhancing surface charge density, achieving effective signal multiplexing, and ensuring long-term stability. This review provides a comprehensive overview of triboelectric mechanisms, working modes, influencing factors, performance enhancement strategies, and wearable health applications. Finally, it systematically summarizes the key improvement approaches and future development directions of triboelectric materials for active health, offering valuable guidance for advancing wearable self-powered biosensors.

1. Introduction

With increasing health awareness, the public increasingly pursues scientifically effective exercise. Consequently, smart wearable devices have emerged as a preferred tool for proactive health management. Smart wearable devices can comprehensively utilize various sensors, recognition algorithms, interaction technologies, and storage technologies. They can effectively enhance user’s ability to manage their health, improve their lifestyles, prevent disease, and boost their overall physical and mental health. A large number of studies have been carried out, and sensing technology and energy management are the keys to the development of smart wearable devices. Compared with other energy harvesting technologies, triboelectric units can generate relatively high triboelectric charge density and instantaneous high—power output through the irregular mechanical pulses produced by human movement [1,2]. Moreover, they can be miniaturized using thin and light materials, and can be worn or integrated into clothing and accessories to power wearable devices [3], which is an important development direction in the future.

Soft triboelectric units have good sustainability and combine power supply and sensing functions. Contact electrification and electrostatic induction are the main working mechanisms of the triboelectric unit. According to the mathematical model [4,5,6], triboelectric charges are the most significant factor affecting the output performance of the triboelectric units, and the density and stability of triboelectric charges determine the power generation and sensing capabilities [7,8,9]. To improve the density and stability of triboelectric charges, researchers have conducted preliminary basic research on surface modification, indicating that the power generation and sensing capabilities can be enhanced through surface microstructures. Researchers have improved the performance of triboelectric units through physical and chemical surface modification methods [10]. Physical surface modification involves adjusting the surface structure and morphology, controlling the contact surface shape, and improving the efficiency and performance of the generator. Its main advantage over chemical surface modification is that it is simple to operate and easy to implement [5,6]. Among various strategies, surface microstructural design is one of the most effective approaches. It plays a crucial role in regulating the energy-conversion efficiency and power-generation capacity of triboelectric generators. By increasing the effective contact area, improving friction efficiency, and enhancing stability and wear resistance, surface design can significantly improve device performance and extend service life. In addition, it contributes to strengthening material properties, innovating energy-harvesting methods, and optimizing charge distribution. Methods such as constructing micro-patterns with sandpaper [11], creating wrinkled micro/nano hierarchical structures [12], endowing with super—hydrophobic properties [13], mimicking the skin surface structure [14], preparing microstructures by dry etching [15], and preparing microstructures by wet etching [16] can increase the effective friction area and roughness of the contact materials, resulting in a several—fold increase in output performance.

As research deepens, more and more evidence show that triboelectric charges will produce a “mosaic” distribution phenomenon of positive and negative charges inlaid with each other [17,18]. Both the team led by Wang’s [19] and Yang’s group [1] both have discovered a new bottleneck problem in improving the output performance of triboelectric units electrical breakdown behavior. As the charge density on the contact surfaces increases, a strong electric field will be generated during the contact—separation process of the two contact surfaces, and the surface microstructures will exacerbate the intensity and non—uniformity of the local electric field. When the electric field intensity exceeds the threshold, electrical breakdown behavior (electron avalanche) will occur between the two contact surfaces, reducing the electrical output performance of the triboelectric unit [20,21,22,23]. Academician Wang’s team constructed a theoretical model based on Paschen’s law to predict the maximum triboelectric charge density on the friction layer and conducted preliminary experimental verification [19]. The experimental results show that the theoretical results are consistent with the experimental results for the fluoroethylene tetrafluoroethylene copolymer film with a thickness in the range of 50–120 microns. On this basis, the applicant’s team extended the above—mentioned theoretical model to ultra-thin films by combining the field—emission theory and Paschen’s law and preliminarily considered the influence of surface morphology on electrical breakdown behavior [1]. An ultra—high surface equivalent charge density of 250 μC/m² (the highest in the existing literature) was achieved in an air environment through experiments, and the electrical breakdown phenomenon was observed [2]. In addition, the stress distribution on the contact surface is also non—uniform during the contact—separation process. These research results have taken a crucial step in understanding the maximum triboelectric charge density of triboelectric units and improving their output performance. Triboelectric units with surface microstructures have problems of non—uniform electric and force fields and are prone to electrical breakdown, so further regulation of power generation and sensing capabilities is required.

Humans are the end—users of intelligent wearable devices and also a huge mobile energy source [24,25]. The human body consumes up to 1.07 × 10⁷ joules of energy per day, and most of this energy is dissipated into the surrounding environment in different forms without being fully utilized. Among them, the mechanical energy that can be collected from leg movements (footfalls) can reach a power of up to 67 watts. Applying this mechanical energy to intelligent wearable devices can meet the continuous operation requirements of most such devices. In the future, wearable energy sources developed based on human activities will be an important way to supply energy for intelligent wearable devices. Triboelectric units have advantages such as excellent power-generation and sensing capabilities, durability, and ease of integration with existing fabrics.

Triboelectric sensors demonstrate excellent applicability and can be used in fields such as active health, industrial robotics, human–machine interaction, and the Internet of Things, which have won the favor of researchers [26,27,28]. Based on the characteristics of human activities, triboelectric units can be installed at different parts of the body to explore self-powered sensing technology. To improve the stability of the performance of triboelectric units, further regulation of power—generation and sensing capabilities is required. Although re-searchers have made many attempts, no predictive model that explains the formation of mosaics at different length scales has been proposed yet. In addition, during the contact—separation process, the deformation of surface microstructures and the generation of triboelectric charges occur within an extremely short time and in a very small gap, making experimental testing and observation extremely challenging. Flexible electronic devices have mechanical properties that match those of biological tissues and excellent ability to conform to curved surfaces. The properties of the contact interface can directly affect the reliability of human–machine interaction and the comfort, stability, and sensitivity of the device, which are the keys to the development of high-performance flexible sensors, wearable energy sources, and intelligent wearable devices.

This paper conducts a comprehensive and timely review. First, it reviews the working modes of triboelectric nanogenerators (TENGs) and the mechanism of charge generation. Then, it specifically introduces the optimization methods of biomimetic surface microstructures and further elaborates on the distribution of triboelectric surface charges and their impacts. On this basis, it details the applications of triboelectric sensors in the field of active health, with a focus on analyzing the applications and application prospects in four aspects: respiratory monitoring, motion posture monitoring, all-weather health monitoring solutions, and fully self-powered energy collection technology. Furthermore, the challenge and future research direction in the related field are deliberated.

2. Mechanism and Modification of Triboelectric Materials

2.1. Triboelectric Mode and Common Mechanism

As shown in Figure 1a, triboelectric modes can be classified into (i) contact–separation mode, (ii) lateral sliding or rotating mode, (iii) single-electrode mode, and (iv) freestanding modes. Figure 1b depicts the situation in which, before two materials come into atomic-scale contact, their electron clouds remain separated without overlap [29]. This corresponds to the attractive force region. In this state, electrons are confined within potential wells of specific orbitals, preventing them from escaping freely, as is typical for nonconducting materials. When atoms from the two materials approach and make contact, their electron clouds overlap to form ionic or covalent bonds. Under additional compressive force, the bond length becomes further shortened. Consequently, the initial single potential well evolves into an asymmetric double-well potential, and the energy barrier between them is reduced due to the strong electron cloud overlap. At this stage, electron transfer can occur from one atom to the other, giving rise to charge exchange.

The role of mechanical contact is therefore to reduce the interatomic distance and promote significant electron cloud overlap in the repulsive region, at least in localized atomic-scale contact areas, despite the macroscopic size of the samples. It should be noted that only a very small fraction of the two surfaces actually reaches atomic-scale contact. This also explains why stronger rubbing or pressing enhances charge transfer: the higher compressive force during sliding can induce local fracture or plastic deformation. After separation, the transferred electrons remain as static charges on the material surface.

As illustrated in Figure 1b, the energy released during electron transfer from dielectric A to dielectric B may appear as photon emission, plasmon excitation, or phonon excitation. Photon emission, when present, can be used to study transitions between the surface states of dielectric A and B. The emitted photons are expected to carry energies on the order of tens of eV, potentially producing UV, visible, microwave, or even THz radiation during contact. If such light emission is experimentally observable, it could provide the basis for a new form of optical spectroscopy to probe electronic transitions at interfaces. These possibilities, however, remain to be confirmed experimentally.

Most importantly, the fundamental molecular mechanism underlying the generation of static charge remains poorly understood, particularly when the contact involves at least one insulating material. As shown in Figure 2a, three main mechanisms have been proposed in previous studies: electron transfer, ion transfer, and material transfer [31]. Without a clear understanding of the fundamental molecular mechanism and a consistent conceptual framework, it is difficult to fully elucidate the properties and behaviors of this phenomenon. It is well established that electron transfer governs contact electrification (CE) between two metals. This process is a strong effect that should not be neglected in CE between a liquid and a solid, and therefore electron transfer should also be considered in the formation of the electric double layer (EDL).

As illustrated in Figure 2b, the hybrid EDL model (often referred to as Wang’s hybrid layer), first proposed by Wang et al. in 2018, introduces a “two-step” process that accounts for both electron transfer and ion adsorption (chemical interaction) [32]. In the first step, molecules and ions in the liquid collide with the solid surface due to thermal motion and liquid pressure. The overlap between the electron clouds of the solid atoms and water molecules facilitates electron transfer between them. For instance, solid materials with strong electron affinity (e.g., polymers containing abundant fluorine groups) can directly capture electrons from water molecules or even from ions in the liquid. Subsequently, liquid flow or turbulence can push the interfacial molecules away from the solid surface. The electron transfer is essentially related to the hopping of electrons from a high-energy state to a lower-energy state. After separation, most of the transferred electrons can remain on the surface if the thermal energy of the electrons (kT, where k is Boltzmann’s constant and T is the temperature) is lower than the energy barrier (Ep). In the second step, free ions in the liquid are attracted to the electrified surface through electrostatic interactions, forming an EDL similar to that in the classical model. Meanwhile, ionization reactions also occur at the solid surface, generating both electrons and ions. When a water molecule loses an electron, it becomes a cation (H₂O+). The lifetime of H₂O+ has been shown to be less than 50 fs, and it rapidly reacts with a neighboring water molecule to produce an OH radical and H₃O+. As a result, the fragmented molecules detached from the solid surface become free ions in the liquid, which can further participate in the formation of the EDL.

2.2. Bioinspired Structural Design

The leaf microstructure-inspired fish gelatin-based triboelectric nanogenerator (LMFG-TENG) consists of positive and negative friction pairs prepared from FG and PDMS films, respectively, conductive layers made of copper foils, spacers composed of sponge layers, and encapsulation layers. Figure 3a illustrates the fabrication process of the leaf microstructure-inspired films [33]. Female molds, replicated from male molds with natural leaf microstructures, are used to fabricate the triboelectric films. By dropping uncured fish gelatin solution onto the female mold and curing it at room temperature for 10 h, FG films are obtained. After peeling off the cured film, patterned positive triboelectric materials are prepared. Similarly, by dropping uncured PDMS solution onto the female mold, curing it in an oven at 80 °C for 1 h, and peeling off the cured film, negative triboelectric films are obtained. It is worth noting that the micro-structured male mold is derived directly from natural leaves. This green mold-transfer technique is pollution-free and low-cost compared with traditional chemical engraving methods. The 5 mm-thick sponge layer placed at the edges of the two friction materials enables complete contact–separation cycles of the TENG under applied pressure. Copper foils attached to the backsides of the friction material films serve as conductive electrodes that can be connected to external equipment. Owing to its flexibility and compact size (5 cm × 5 cm × 5 mm per unit), the wearable and portable LMFG-TENG can be used for self-powered sensing in motion tracking and for powering small electronic devices.

Figure 3b presents skin-inspired, hierarchical polymer architectures for spacer-free, ultrathin, and highly sensitive triboelectric sensors (TESs) [14]. The figure illustrates interlocked microridges with a gradient elastic modulus (E), mimicking the stiff epidermis and soft dermis layers in human skin. This gradient facilitates efficient stress transmission and concentration from microridges to underlying mechanoreceptors. Inspired by this structure, hierarchical nanoporous polymers with interlocked microridge structures and different elastic moduli were fabricated using a solvent-assisted micromolding method. Figure 3c schematically illustrates the synthesis procedure for both flat and crumpled MoS₂ structures [34]. Photonic synthesis approach relies on the thermolysis of spin-coated (NH₄)₂MoS₄ precursor films to form atomically thin 2D MoS₂ layers, followed by laser-directed annealing on a thermally oxidized silicon wafer (Si wafer with a 300 nm-thick SiO₂ layer). This pulsed laser-directed thermolysis method provides a rapid, non-vacuum, wafer-scale, and patternable route for 2D MoS₂ synthesis. By adjusting the morphological structure, internal stress can be introduced into the MoS₂ crystals, leading to surface crumpling. A crumpled MoS₂-based TENG device generates ~40% more power than its flat counterpart. Compared with other MoS₂-based TENG devices, this design achieves high-performance energy harvesting (up to ~25 V and ~1.2 μA) without relying on additional materials, even when the counterpart triboelectric surface has only a slightly different position in the triboelectric series. The enhanced triboelectrification is attributed to both work function modification and increased surface roughness.

2.3. Surface Charge Mosaic

Figure 4a illustrates possible scenarios of contact electrification together with experimental Kelvin force microscopy (KFM) surface potential maps [17,18]. The traditional view assumes that, upon contact and subsequent separation, one surface becomes uniformly positively charged while the other becomes uniformly negatively charged. In contrast, the mosaic model proposes that each surface consists of regions with different propensities to accept or donate charge. Upon contact, these regions accidentally develop distinct charge polarities. This mosaic view of contact electrification is supported by the potential maps. The map corresponding to a pristine PDMS film before contact electrification shows an approximately uniform profile. This profile is close to zero. After contact, the contact-charged surfaces exhibit a mosaic of positively and negatively charged regions. In particular, a piece of PDMS exhibits a predominantly negative surface charge, which is negatively charged. The other one shows positively charged. Meanwhile, there are equal amounts of positive and negative charges generated on the two contact surfaces. Higher effective surface charge density generally leads to higher electric outputs of triboelectric generators. Various efforts have been devoted to achieving high effective surface charge density. Yet high surface charge density will generate a strong electric field in the surrounding media. When the strong field reaches to a threshold value, electric breakdown will occur due to gas-ionization. And the electric outputs of triboelectric generators significantly decrease. To enhance the output power of triboelectric generators, an improved theoretical model combines Paschen’s law of air ionization with field emission theory [1].

$$V_b=\left\{\begin{array}{l}Kx, \mathrm{for}0<x\le x_c\\ {\displaystyle \frac{Bpx}{\ln \left(px\right)+C}},\mathrm{for}{x}_c\le x\le x_{\max }\end{array}\right.$$

(1)

where K is the threshold electric field required for field emission. $C=\ln [A/\ln (1+1/\gamma )]$, $p$ is the gas pressure, $\gamma$ is the secondary ionization coefficient, A and B are constants determined by the composition and the pressure of gas. $x_{\max }$ is the max separation distance between interactive surfaces in triboelectric generators. A critical value, $x_c$, determined by the interception point of the piecewise function, divides the gap distance into two regions.

This model predicts the maximum triboelectric charge density and output power of a generator operating in air, thereby providing important theoretical guidance for material selection, structural design, and surface microstructural optimization. As shown in Figure 4b, in the modified Paschen’s curve under a micro-gap condition, the breakdown voltage exhibits a linear relationship with the electrode spacing, with the slope denoted as K [1]. The threshold value of K can be approximately given in terms the work function and an electric field enhancement factor. This enhancement factor is a product of surface irregularity and gap distance. K can be increased by rising the work function and/or decreasing the surface irregularity and gap distance. A larger K corresponds to a higher maximum equivalent charge density achievable at the contact surface. To investigate how to suppress the field emission effect and thereby increase K, verification experiments using PDMS were conducted. Mechanical stress in pillar-shaped and dome-shaped nanostructures under a downward force was simulated using ANSYS (Academic Research, Release 18.0), as shown in Figure 4c. The square marked with a dotted line in Figure 4d indicates the sector analyzed to characterize the stress distribution. Figure 4c presents the mechanical stress in dome-shaped and pillar-shaped nanostructures deformed by a flat gold layer under applied forces of 0 N, 25 N, and 50 N [35]. Under the same downward force, the stress within the dome-shaped nanostructure was much greater than that within the pillar-shaped one. This difference arises from the high deformability of the dome-shaped structure compared with the relatively low deformability of the pillar-shaped structure. Consequently, stress was concentrated at the top and central region of the dome, leading to repetitive and severe stress accumulation and ultimately to irregular permanent deformation. In contrast, stress in the pillar-shaped nanostructure spread more evenly throughout the body.

Viscoelastic polymer adhesives (VPAs) are common materials broadly used in adhesive tapes for bonding objects tightly in daily life. VPA-based generators (VPAGs) possess unique frequency-insensitive and pressure-enhanced output characteristics. Figure 4d shows the dependence of VPAG output voltages on applied pressure (or VPA-2 area) at different impact frequencies [36]. The VPAG output is essentially independent of impact frequency. This was revealed by systematically varying the contact pressure (1.25–80 bar) through stacking different-sized VPA-2 layers on a fixed VPA-1 base while keeping the impact force at 200 N. Over this 64-fold pressure range the peak voltage first dipped marginally and then rose, yet at every pressure the mean values obtained at 1.9 Hz, 2.5 Hz, and 3.3 Hz overlapped within their wide standard-deviation bands. The absence of any frequency-dependent trend confirms the frequency-insensitive characteristic of VPAGs.

2.4. Charge Dissipation and Self-Restacking

In recent years, TENGs have emerged as a transformative technology for harvesting ambient mechanical energy and converting it into usable electrical power. Their rapid development is closely tied to advances in materials science, particularly the introduction of novel functional materials, interface engineering strategies, and hybrid structures that expand both the efficiency and versatility of these devices. Unlike conventional energy harvesters, which are often constrained by unidirectional inputs and rigid architectures, next-generation TENGs integrate flexible designs, multidimensional energy harvesting, and multifunctional sensing capabilities [37,38,39,40,41].

A key limitation of traditional TENGs is their dependence on directional mechanical input, restricting their applicability in environments where energy sources are multidimensional or stochastic. To address this, the concept of arbitrary directional TENGs has been proposed [39]. By employing geometric optimization, multi-layer configurations, and flexible materials, these devices can effectively harvest energy from arbitrary directions, overcoming the intrinsic anisotropy of conventional structures. The ability to decouple multidimensional mechanical stimuli enables efficient energy conversion from complex and unpredictable motions, such as human activity or environmental disturbances. This makes arbitrary directional TENGs particularly suited for wearable electronics and biomedical implants, where consistent and reliable power supply under non-uniform motion is essential.

In parallel, the incorporation of novel electronic materials has opened new avenues for TENG performance enhancement and multifunctionality. A notable example is the use of multi-layer quasi-2D perovskites as active materials [41]. These structures not only maintain high triboelectric output but also exploit strong interfacial polarization effects and tunable electronic band structures. Beyond energy harvesting, quasi-2D perovskite-based TENGs have demonstrated potential for neuromorphic applications, where memory-like synaptic responses can be integrated into self-powered systems. Such characteristics make them promising candidates for electronic skin (e-skin), combining sensory functions, self-sustainability, and neuromorphic computing capabilities. The synergy between energy harvesting and artificial sensory perception indicates a paradigm shift from passive power devices to intelligent self-powered systems.

Beyond energy harvesting, self-powered sensing and human–machine interfacing represents another important research frontier. A recent study reported an F8BT-based humidity sensor with outstanding sensitivity and fast reversible responses [40]. Unlike conventional humidity sensors that rely on external power supplies, F8BT-based devices offer integration with TENGs to achieve autonomous operation. Importantly, this work linked humidity sensing to applications in the metaverse, where immersive human–machine interactions require real-time environmental feedback. By enabling humidity-driven feedback loops in wearable or VR interfaces, such sensors could provide more natural and intuitive interactions. The convergence of TENG-based self-powering and F8BT-based sensing exemplifies the shift in triboelectric research toward interactive, multifunctional, and intelligent systems.

Simultaneously, the exploration of 2D materials and multi-component frameworks has significantly advanced the field. MXenes, owing to their high electrical conductivity, tunable surface terminations, and layered morphology, have been extensively studied as triboelectric and conductive components. Recent work integrating MXene/graphene oxide (GO)/siloxene frameworks onto textile substrates [38] presents a milestone in wearable self-powered electronics. The hybrid framework enhances charge density and structural stability while maintaining mechanical flexibility. Embedding these frameworks into fabrics transforms ordinary textiles into active platforms for continuous energy harvesting and sensing, paving the way for smart textiles in healthcare monitoring, sports analytics, and daily interactive electronics. The sustainable and durable characteristics of such frameworks further align with the global demand for environmentally friendly energy technologies.

However, MXene’s intrinsic limitations, such as interlayer stacking and limited accessible surface area, hinder its performance optimization. To overcome this, a novel silica nanosphere intercalation approach has been introduced [37]. By inserting functionalized silica nanospheres between MXene layers, the interlayer spacing is enlarged, thereby improving charge storage capacity and enhancing triboelectric performance. This strategy directly addresses the bottleneck of charge accumulation and transport in MXene-based TENGs. Moreover, the intercalation approach provides a versatile framework for tailoring MXene properties across broader applications, including supercapacitors, flexible energy storage, and high-output TENGs. Such bottom-up material engineering complements device-level architectural optimization, offering a holistic paradigm for designing next-generation self-powered systems.

Taken together, these five studies illustrate the multi-dimensional evolution of TENGs and self-powered devices. From structural innovations [39] to novel material incorporation [38,41], and from functional integration to interfacial engineering [37], they collectively underscore the central role of charge regulation and interface design in advancing device performance. By tailoring surface energy states, interlayer spacing, and polarization intensities, researchers can achieve enhanced charge separation, storage, and multifunctionality in TENGs.

Material innovation is central to enhancing TENG performance and versatility. Polymer blend-based systems are particularly promising, as combining high-dielectric polymers with flexible elastomers balances surface charge density, mechanical compliance, and long-term durability. These blends also offer improved tolerance to humidity and temperature, while tunable interfacial interactions enhance charge trapping and reduce leakage, critical for wearable devices. Electrospinning-based systems complement this approach by producing nanofiber mats with controlled morphology, alignment, and porosity, increasing surface area and triboelectric efficiency. Challenges in long-term charge retention and stability can be addressed by combining electrospinning with polymer blends or charge-stabilizing additives, yielding flexible, high-performance hybrid nanostructures. Integrating these material strategies with multidirectional architectures, multilayer stacking, and hybrid 2D frameworks enables TENGs that are high-performing, multifunctional, and resilient. Electrospun polymer blend mats, for example, can serve as wearable energy harvesters and sensors, highlighting the potential of combining polymer blending, nanofiber engineering, and interfacial design for flexible, sustainable, and intelligent triboelectric devices.

Looking forward, three emerging trends are expected to define the trajectory of the field. First, the integration of self-powering and intelligence will transform TENGs from passive harvesters into autonomous sensory-computing units, with potential impacts in neuromorphic e-skin and artificial intelligence applications [41]. Second, the coupling of TENGs with human–machine interaction platforms—particularly in immersive environments such as the metaverse—suggests that self-powered sensors will form the backbone of next-generation interactive technologies [40]. Third, the drive toward sustainability and adaptability will continue to emphasize flexible, wearable, and environmentally compatible energy solutions, exemplified by textile-based MXene frameworks and multidirectional TENGs [38].

3. Active Health Applications

3.1. Biochemical Indicators Monitoring

Monitoring human biochemical indicators is essential for healthcare, disease prevention, and personalized medicine. Conventional sensing systems depend on bulky instruments and external power supplies. These limitations reduce their portability and long-term applicability. TENGs have recently gained attention as versatile platforms. They can convert biomechanical activities into electrical signals and allow continuous, noninvasive monitoring of various biochemical markers.

Figure 5a introduces a fiber-based TENG wearable sensor capable of simultaneous sweat analysis and motion monitoring [42]. The TENG structures are fabricated into stretchable fibers that can be woven into textiles, forming a self-powered platform suitable for daily wear and medical diagnostics. Constructed from conductive fibers and flexible polymers, the fiber TENG generates triboelectric signals under mechanical deformations such as stretching, bending, or compression. Through surface modification, the sensor enables selective interactions with ions and metabolites in sweat. Experimental results demonstrate its high sensitivity in detecting pH, electrolytes, and secretion rates during physical exercise, while simultaneously recording motion amplitude and frequency. This dual-modal design allows real-time assessment of hydration status, fatigue level, and motor function, representing a significant advancement toward integrated wearable systems. Figure 5b [43] highlights humidity sensing. A nanohybrid layer composed of SnS₂ nanoflowers and reduced graphene oxide provides a high specific surface area and excellent conductivity. In this configuration, the TENG functions both as an energy harvester and as a signal amplifier, enabling self-powered humidity detection without the need for an external power supply. The device exhibits high sensitivity, rapid response, and long-term stability on flexible substrates. When placed near the nose or mouth, it monitors real-time humidity variations in breath, providing an indirect indicator of respiratory health. This approach expands the applicability of self-powered sensing to both environmental monitoring and biomedical fields.

Conventional materials often trap moisture, thereby restricting long-term usability. By incorporating micro-hill arrays, the authors achieve directional moisture transport driven by Laplace pressure differences and wettability gradients, enabling droplet removal within 2.25 s [44]. The material also exhibits a rapid pressure response (29.1/37.0 ms), supporting both respiration and motion monitoring. This work enhances comfort as well as functionality in flexible electronic skins. Figure 5c [45] describes a hydrogel-based sweat sensor with self-healing properties. Nanocellulose enhances mechanical strength and stability while providing abundant hydroxyl groups for functionalization. The sensor can recover its structural and electrical properties after damage such as bending, scratching, or fracture, thereby significantly extending its operational lifespan. It accurately monitors sweat secretion rate and ionic concentration, showing strong correlation with physiological activity. The adoption of green, self-healing materials presents a sustainable strategy for developing robust wearable biosensors.

In addition, a cellulose aerogel-based system incorporates a silver sensing layer between the aerogel and permeable polyurethane layers. This device demonstrates high mechanical strength, large strain tolerance, and excellent breathability. It achieves high sensitivity (gauge factor ≈ 238), an ultralow detection limit (0.1%), and a fast response time (18 ms), enabling dual-modal strain and humidity sensing [46]. Its long-term wearing comfort, recyclability, and environmental friendliness highlight its potential for next-generation on-skin electronics. Furthermore, a self-adhesive material exhibits strong adhesion, high mechanical robustness [47], and tunable conductivity via concentration adjustment. An associated ICE-TENG achieves a power density of 151.3 μW cm⁻², sufficient to operate small electronic devices. Organogel-based strain sensors also perform reliably underwater, thereby broadening the scope of wearable sensing and human–machine interaction.

Figure 5d presents an e-skin capable of simultaneous pressure and temperature sensing [48]. Embedded TENG structures generate distinct electrical signals for each stimulus without cross-interference. Operating without an external power source, the e-skin demonstrates high sensitivity, providing a practical solution for multimodal self-powered wearables. The bionic skin also features high breathability, directional sweat transport [49], and accurate metabolite detection (e.g., glucose, lactate, pH), in addition to temperature, impedance, and EMG monitoring. Its comprehensive functionality makes it a promising platform for personalized healthcare and rehabilitation. In addition, a hybrid electrode composed of nanofibers and liquid metal [50], exhibits ultralow resistance (52 mΩ sq⁻¹), high stretchability (up to 570%), and durability over 330,000 cycles. It maintains performance under extreme conditions such as exposure, immersion, and mechanical damage, thereby outperforming existing electrodes and advancing the development of robust e-skins. Flexible self-powered multimodal sensors further demonstrate high thermal sensitivity (−0.055 °C⁻¹ below 40 °C), a broad pressure range [51] (0.2–120 kPa; sensitivity: 8.254 V kPa⁻¹), and stable humidity monitoring. Tests conducted on robotic hands confirm their capability for simultaneous sensing of humidity, water temperature, and object weight, highlighting their potential for integrated human–environment–machine interfaces.

Figure 5e shows a mask with embedded TENG layers within its filters [52]. Breathing-induced airflow generates periodic signals reflecting respiratory rate, depth, and anomalies. Validated under both rest and physical activity, the mask supports clinical diagnosis, therapeutic evaluation, and contactless human–machine interaction, merging protection with self-powered monitoring. Figure 5f [53] demonstrates a mask capable of electroporation-based sterilization using TENG outputs driven by respiration. Embedded electrodes generate high-voltage pulses that disrupt microbial membranes, inactivating bacteria within minutes without chemicals or external energy. This rapid, residue-free disinfection strategy broadens the application of TENGs in protective equipment.

Figure 5g focuses on non-enzymatic lactate detection [54]. Molecularly imprinted polymers (MIPs) provide stable and selective recognition of lactate molecules, overcoming limitations of enzyme-based methods. Integrated with a TENG transducer, the sensor enables continuous, self-powered lactate monitoring during exercise, showing strong correlation with physiological concentrations. This strategy underscores the potential of TENG–MIP integration for sports science, metabolic disease management, and telemedicine.

The self-disinfecting face mask integrates a Cu(OH)₂ nanowire electroporation filter driven by a respiration-activated TENG (R-TENG) [53]. The R-TENG, fabricated from electrospun PVA and PVDF membranes, utilizes a dome-shaped PVA structure to maximize contact area. Coupled with β-phase-enriched PVDF, it achieves an open-circuit voltage of 120 V at normal breathing rates, generating a localized electric field of 19 MV·m⁻¹ at the nanowire tips. This enables synergistic electroporation and physical penetration, resulting in >99.9% bacterial inactivation—significantly higher than mechanical penetration alone (90–99%). This study pioneers R-TENG-driven electroporation for real-time mask disinfection, offering a pathway to advanced protective equipment. Complementing this, a virus-blocking textile (VBT) [55] harvests triboelectric energy from body movement to generate a continuous negative potential. This induces Coulombic repulsion against negatively charged SARS-CoV-2 aerosols, reducing viral penetration by 99.95% in chamber tests—a 13-fold decrease in viral load. This approach combines sustainable energy harvesting with electrostatic protection, providing an effective barrier against airborne transmission.

With heightened emphasis on antimicrobial strategies in the post-COVID-19 era, TENGs have demonstrated broad efficacy in water, air, surface, and wound disinfection [56]. In wound management, multiple studies have illustrated the versatility of TENG-based therapies. For example, Figure 5h [57] describes an ionic patch that utilizes TENG output to generate a stable electric field, thereby enhancing cell migration, proliferation, and collagen deposition. This approach markedly accelerated wound closure and reduced scarring in animal models, outperforming passive dressings by providing continuous, self-powered bioelectric stimulation. Building on this, Figure 5i [58] integrates electrical stimulation with photothermal therapy. In this design, a flexible TENG harvests biomechanical energy to drive photothermal agents (e.g., graphene) under NIR irradiation, enabling simultaneous bacterial eradication and tissue repair. This dual-mode therapy proved particularly effective in murine models of chronic and infected wounds. Further integrating multifunctionality, Figure 5j presents a TENG patch engineered for dual drug release and electrostimulation [59]. The device enhances drug permeability and improves local microcirculation through applied electric fields, thereby yielding synergistic healing effects in infected wounds while also reducing inflammation. Moreover, covalent bonding of levofloxacin to carbon quantum dots enables concurrent antibacterial action and electrical conductivity. In vivo experiments confirmed that this combined treatment outperformed individual therapies, highlighting a novel strategy for infected wound care [60]. For inflammatory skin disorders, a battery-free microneedle system was developed by integrating a TENG with remodel able metallic microneedles. This system enables both transdermal drug delivery and pulsed electrical stimulation, thereby promoting immunomodulation and restoring tissue homeostasis [61]. In psoriasis models, it achieved significantly greater therapeutic efficacy compared with monotherapies. In diabetic wound management, a hydrogel-based electronic dressing has been designed to combine programmable drug delivery with electrical stimulation. When tested in diabetic rats [62], the device promoted wound closure while minimizing secondary injury associated with frequent dressing changes.

Beyond topical applications, TENGs can generate high-voltage pulses for efficient electroporation [63]. They have successfully delivered macromolecules and plasmid DNA into cells with efficiencies comparable to commercial systems, offering a miniaturized alternative for biomedical applications. In regenerative implantology, a drug-eluting bilayer vascular graft with integrated triboelectric sensing capability has been developed. This scaffold supports re-reendothelializations [64], inhibits thrombosis, and monitors hemodynamics in real time, representing a multifunctional solution for small-diameter vascular grafts. Under ultrasound activation, biodegradable TENGs can generate alternating electric fields that trigger the release of docetaxel, thereby disrupting cytoskeletal dynamics and inducing apoptosis within 90 min [63], markedly faster than conventional approaches.

Collectively, these studies underscore the expanding utility of TENGs in disinfection, wound healing, drug delivery, and implantable therapies. Ongoing material and structural innovations continue to enhance device functionality and integration. Nevertheless, challenges remain regarding signal stability, long-term usability, data processing, and scalable fabrication. Addressing these limitations will be critical for accelerating the translation of TENG-based technologies into practical biomedical applications.

Figure 5. TENGs as self-powered platforms for biochemical monitoring and therapeutic applications. (a) Fiber-based stretchable TENGs for real-time sweat analysis (pH, electrolytes, secretion rate) and motion capture, reprinted/adapted with permission from Ref. [42]. (b) SnS₂/rGO hybrid TENG sensors for humidity monitoring and respiratory assessment, reprinted/adapted with permission from Ref. [43]. (c) Self-healing nanocellulose hydrogel TENGs for stable sweat ion detection, reprinted/adapted with permission from Ref. [45]. (d) Electronic skin with decoupled pressure–temperature perception, reprinted/adapted with permission from Ref. [48]. (e) Self-sensing respiratory masks for breathing pattern monitoring, reprinted/adapted with permission from Ref. [52]. (f) Respiration-driven TENG masks enabling instant disinfection via electroporation [53]. (g) Molecularly imprinted polymer (MIP)-based TENGs for lactate monitoring in sweat, reprinted/adapted with permission from Ref. [54]. (h) A TENG-driven ion-conductive patch accelerates wound healing and reduces scarring, reprinted/adapted with permission from Ref. [57]. (i) Photothermal TENG patches for wound healing acceleration, reprinted/adapted with permission from Ref. [58]. (j) Surface-engineered TENG patches combining drug delivery and electrical stimulation for infected wound repair, reprinted/adapted with permission from Ref. [59].

Figure 5. TENGs as self-powered platforms for biochemical monitoring and therapeutic applications. (a) Fiber-based stretchable TENGs for real-time sweat analysis (pH, electrolytes, secretion rate) and motion capture, reprinted/adapted with permission from Ref. [42]. (b) SnS₂/rGO hybrid TENG sensors for humidity monitoring and respiratory assessment, reprinted/adapted with permission from Ref. [43]. (c) Self-healing nanocellulose hydrogel TENGs for stable sweat ion detection, reprinted/adapted with permission from Ref. [45]. (d) Electronic skin with decoupled pressure–temperature perception, reprinted/adapted with permission from Ref. [48]. (e) Self-sensing respiratory masks for breathing pattern monitoring, reprinted/adapted with permission from Ref. [52]. (f) Respiration-driven TENG masks enabling instant disinfection via electroporation [53]. (g) Molecularly imprinted polymer (MIP)-based TENGs for lactate monitoring in sweat, reprinted/adapted with permission from Ref. [54]. (h) A TENG-driven ion-conductive patch accelerates wound healing and reduces scarring, reprinted/adapted with permission from Ref. [57]. (i) Photothermal TENG patches for wound healing acceleration, reprinted/adapted with permission from Ref. [58]. (j) Surface-engineered TENG patches combining drug delivery and electrical stimulation for infected wound repair, reprinted/adapted with permission from Ref. [59].

Across these biochemical monitoring platforms, fiber-based TENGs utilize stretchable polymers and conductive fibers for dual sweat and motion sensing; nanohybrid SnS₂/rGO layers enhance conductivity and surface area for rapid humidity detection; hydrogel-based materials provide self-healing and mechanical resilience for long-term sweat ion monitoring; while cellulose aerogel composites combine breathability, strain tolerance, and recyclability. This comparison highlights how material composition and micro/nano-scale structuring synergistically dictates sensitivity, durability, and multimodal sensing capability in wearable biochemical TENG devices. In therapeutic applications, hydrogel- and organogel-based patches deliver self-powered electrical stimulation and drug release, while flexible electrodes with metallic or nanostructured coatings enable high-voltage electroporation for sterilization. The combination of soft, biocompatible matrices with conductive nanostructures ensures mechanical conformability, reliable energy transduction, and multifunctional therapeutic performance, illustrating the critical role of material selection and surface engineering in clinical TENG applications.

3.2. Posture and Gait Monitoring

Recent advances in TENGs (TENGs) have highlighted their significant potential for flexible, wearable, and self-powered sensing in domains such as human activity monitoring, health assessment, and sports applications. From a materials perspective, Figure 6a presents Bromo Isobutylene Isoprene Rubber (BIIR) as a core triboelectric material [65]. BIIR offers excellent flexibility, mechanical stability, and intrinsic antibacterial properties, thereby addressing reliability concerns in wearable sensors frequently exposed to sweat or bacterial environments. By optimizing micro- and nano-scale surface structures, the device achieves simultaneous mechanical signal detection and self-powered operation, exemplifying a material strategy that integrates biosafety with triboelectric functionality. Furthermore, by dispersing perovskite nanofillers into natural polymers [66], the resulting composite rubber achieves a high surface charge density, enhanced mechanical robustness, and efficient energy harvesting capabilities, enabling real-time monitoring across diverse human activities. Collectively, these findings underscore the critical role of material selection and surface engineering in advancing the performance of wearable TENGs. Beyond individual wearables, contextual and systemic sensing strategies have broadened the application scope of TENGs. As illustrated in Figure 6b, shoe–floor contact can be harnessed to convert walking and running motions into electrical signals [67]. When coupled with integrated pattern recognition algorithms, this approach enables precise motion discrimination, proving particularly valuable for fall detection in elderly or clinical populations. Unlike camera- or IMU-based systems, this self-powered and non-invasive solution circumvents environmental and privacy constraints, thereby offering distinct advantages for smart elderly care and rehabilitation.

Figure 6c illustrates a flexible triboelectric pressure sensor (FTPS) array with high sensitivity, breathability, and self-powered operation [68]. When coupled with an LSTM model, the system achieves a gait classification accuracy of 94.23%, providing a viable solution for real-time gait analysis, health assessment, and early disease diagnosis. The optimized sensor architecture ensures rapid response, mechanical durability, and fault tolerance, enabling accurate discrimination of various motion modes, including standing, turning, and obstacle crossing [69]. Furthermore, conductive sponge–based TENGs achieve ultralight force detection and serve as both energy harvesters and motion sensors, offering long-term operational stability and underscoring scalable solutions for continuous health monitoring and energy harvesting in wearable form factors [70]. In the context of professional sports and complex motion monitoring, TENGs have been adapted to capture high-intensity dynamic movements. Figure 6d,f demonstrate a P(VDF-co-HFP)/MXene composite that leverages enhanced dielectric properties, conductivity, and mechanical robustness to monitor respiration, trunk posture, and athletic performance [71]. This system enables real-time quantitative performance assessment and holds promise for injury prevention, illustrating the adaptability of TENGs in high-impact scenarios. The composite can also be integrated inside the mask to monitor changes in respiratory status before and after basketball exercise. In detail, when a person breathes, it drives the collision and friction between the composite film and the mask cloth, leading to a voltage signal that reflects the breathing situation.

Concurrently, advances in structural engineering at the material level have further improved TENG performance and sustainability. Figure 6e reports the development of nanocellulose aerogels with hierarchical architectures that increase surface contact area, charge storage capacity, and overall TENG output [72]. This eco-friendly, lightweight, and high-performance material platform is well suited for applications in medical monitoring, protective equipment, and energy harvesting. In addition, badge reel–shaped TENG sensors are capable of accurately capturing movements of the knee, arm, neck, waist, and spine with high resolution and long-term durability [73]. Such devices provide lightweight, real-time monitoring solutions for posture correction, rehabilitation training, and the prevention of musculoskeletal disorders. By combining a retractable badge reel and the grating-structured TENG, a small-volume and high-precision stretch sensor has been developed for wearable and real-time monitoring human motions. The sensor retains a simple operation principle of a retractable reel: with two ends placed on the subject body, it extends or contracts as the human subject bends or stretches.

Figure 6. TENG-based wearable systems for self-powered posture and gait monitoring. (a) BIIR-based flexible sensors for skin-attachable posture detection, reprinted/adapted with permission from Ref. [65]. (b) Shoe–floor triboelectric sensing for motion recognition and fall detection, reprinted/adapted with permission from Ref. [67]. (c) Flexible pressure sensor array in smart insoles for plantar pressure mapping and gait analysis, reprinted/adapted with permission from Ref. [68]. (d) P(VDF-co-HFP)/MXene-based sensors for respiration, reprinted/adapted with permission from Ref. [71]. (e) Nanocellulose aerogels with multiscale structures enhancing triboelectric performance for future posture-sensing applications, reprinted/adapted with permission from Ref. [72]. (f) P(VDF-co-HFP)/MXene-based sensors for posture tracking in basketball motion, reprinted/adapted with permission from Ref. [71].

Figure 6. TENG-based wearable systems for self-powered posture and gait monitoring. (a) BIIR-based flexible sensors for skin-attachable posture detection, reprinted/adapted with permission from Ref. [65]. (b) Shoe–floor triboelectric sensing for motion recognition and fall detection, reprinted/adapted with permission from Ref. [67]. (c) Flexible pressure sensor array in smart insoles for plantar pressure mapping and gait analysis, reprinted/adapted with permission from Ref. [68]. (d) P(VDF-co-HFP)/MXene-based sensors for respiration, reprinted/adapted with permission from Ref. [71]. (e) Nanocellulose aerogels with multiscale structures enhancing triboelectric performance for future posture-sensing applications, reprinted/adapted with permission from Ref. [72]. (f) P(VDF-co-HFP)/MXene-based sensors for posture tracking in basketball motion, reprinted/adapted with permission from Ref. [71].

These studies reflect a coherent technological progression. Innovations in triboelectric materials, surface functionalization, and structural engineering have enabled the development of wearable, self-powered sensors. Their integration into platforms such as insoles, shoe–floor interfaces, and badge-like wearables has facilitated applications in health monitoring and gait analysis. Furthermore, adaptation to dynamic and high-impact environments has extended TENG applications to sports science, rehabilitation, and sustainable energy harvesting. This integrated perspective highlights the potential of TENGs to unify mechanical sensing, energy autonomy, and biosafety in next-generation wearable and intelligent systems.

Although TENG-based posture and gait monitoring has demonstrated considerable promise, several critical limitations must be addressed before large-scale deployment in daily healthcare and rehabilitation applications. (i) Signal stability and environmental adaptability: The translation TENG-based posture and gait monitoring into daily wearables requires signal stability under uncontrolled environments. The triboelectric effect is inherently sensitive to humidity, sweat, temperature, and mechanical perturbations, all of which degrade charge retention and induce spurious fluctuations. Biomechanical variability, including gait asymmetry, body weight, and terrain, further compromises signal consistency, limiting clinical reliability. Future solutions should enhance environmental tolerance through hydrophobic yet breathable encapsulation (e.g., PDMS or fluorinated coatings) and redundancy via multi-point arrays. Adaptive signal conditioning, incorporating real-time filtering and outlier rejection, can further stabilize motion recognition across heterogeneous conditions. (ii) Wearability, comfort, and human-device interaction: Long-term usability hinges on comfort and unobtrusiveness. Current designs, often multilayered or locally rigid, impede natural movement and reduce compliance. Anatomical diversity and activity-specific biomechanics further challenge one-size-fits-all designs. Next-generation devices should adopt ultrathin, skin-conformal materials such as nanofibers or hydrogels, ensuring mechanical compliance and minimizing irritation. Modular architectures, combining baseline monitoring patches with detachable high-sensitivity nodes, offer adaptability without compromising comfort. Iterative co-design with patients, athletes, and elderly users is essential to align technical performance with real-world acceptability. (iii) Power density and continuous energy supply: While TENGs provide self-powered operation, their pulsed high-voltage output mismatches the continuous low-voltage demand of wearable electronics. Consequently, most systems rely on auxiliary storage or external sources. Integration of micro-supercapacitors or thin-film batteries can buffer energy, while hybrid harvesters combining triboelectric, piezoelectric, and thermoelectric effects offer greater stability. On the electronics side, ultra-low-power circuits, energy-aware protocols, and adaptive duty cycling are critical. Energy-adaptive algorithms that dynamically tune sampling and computation may ultimately enable fully self-sustained operation. (vi) System integration and miniaturization: Despite advances in sensitivity, many prototypes remain tethered to bulky external circuits. True miniaturization demands monolithic integration of TENGs with flexible transistors, rectifiers, and wireless modules on stretchable substrates. Self-sufficient centimeter-scale nodes that combine harvesting, processing, and communication represent a promising direction. Distributed wireless networks, coupled with energy-efficient protocols such as backscatter or ultra-wideband telemetry, can further reduce energy costs. Local feature extraction with transmission of only high-level summaries minimizes computational load and prolongs operation. (v) Durability, mechanical fatigue, and longevity: Repetitive contact, bending, and sliding impose severe mechanical fatigue on TENGs, leading to wear, delamination, and signal degradation. Shoe-integrated systems, subjected to thousands of cycles daily, are particularly vulnerable. Durability can be improved via wear-resistant coatings, self-recovering microstructures, or self-healing polymers capable of autonomous crack repair. Biostability is equally critical: long-term skin contact necessitates antimicrobial surfaces and biocompatible materials. For disposable applications, biodegradable composites provide sustainable alternatives without sacrificing performance.

For posture and gait sensing, elastomeric materials offer inherent flexibility and antibacterial properties. When combined with micro/nano-scale surface engineering, these materials collectively influence the sensitivity, response speed, durability, and long-term wearability of the devices, underscoring the critical role of tailored material structure integration in achieving precise and reliable motion monitoring.

3.3. All-Weather Health Monitoring

All-weather health monitoring leverages self-powered and flexible sensing platforms to continuously track cardiovascular, respiratory, motion, and sleep signals in daily life. TENG-based systems enable real-time, long-term monitoring with high sensitivity, environmental adaptability, and wireless integration. These multimodal, wearable sensors support personalized healthcare, early disorder detection, and energy harvesting, paving the way for smart, continuous, and ubiquitous health management.

Figure 7a shows an acoustically enhanced TENG stethoscope. By integrating an optimized acoustic cavity with a flexible membrane, the device transduces minute cardiac vibrations into high-amplitude electrical signals, enabling clear identification of S1, S2, and pathological murmurs even under low-frequency noise [74]. The exploded view illustrates the internal structure of the designed instrument, which primarily comprises an auscultatory cavity and a triboelectric acoustic sensor (TAS). Serving as the core electromechanical transduction component of the stethoscope, the TAS is fabricated by assembling a fluorinated ethylene propylene (FEP) film covered with a perforated aluminum (Al) top layer, a spacer creating an air gap, and a polyimide (PI) membrane coated with a sputtered gold layer. To increase the surface charge density, nanostructures are fabricated on the FEP surface using inductively coupled plasma (ICP) etching. This system provides reliable auxiliary diagnosis in multiple cardiac disease models and underscores the potential of TENGs in noninvasive, real-time cardiac monitoring. These systems employ intelligent algorithms to process TENG-generated signals and deliver real-time health feedback, operating continuously for several days without external power. Similarly, Figure 7b shows a textile-based triboelectric sensor (TS) with a bilayer structure—comprising silver-coated polyester fabric and embossed hybrid fibers [75]. The device achieves high sensitivity (3.88 V/kPa) within the 0.1–4.3 kPa range and can capture weak pulses even in elderly subjects. When integrated into a wireless biosensing system (WBS) with signal conditioning, Bluetooth transmission, and smartphone interfacing, the platform demonstrated long-term stability (after 80,000 loading-unloading cycles, mechanically performance is also stable), humidity tolerance, 10–95% relative humidity, (RH), and reliable operation across various body locations, highlighting its feasibility for self-powered, personalized health management. Respiratory health monitoring has also seen notable innovation. Figure 7c shows an inhalation-driven vertical flutter TENG (VF-TENG) embedded in gas masks [76]. It harnesses airflow-induced membrane vibrations to generate output currents of tens to hundreds of microamperes and voltages up to several hundred volts—sufficient to power integrated micro-sensors and wireless communication modules. Expanding into multimodal health sensing, smart wearable sensors based on TENGs have been incorporated into flexible patches and wristbands for simultaneous tracking of heart rate, respiration, and physical activity, as demonstrated in Figure 7d,i [77].

Beyond respiratory monitoring, this system illustrates the potential of TENGs in multifunctional protective equipment. To further improve robustness in humid environments, an all-nanofiber self-powered respiratory sensor (ASRS) maintains a pressure sensitivity of 0.048 kPa⁻¹ under varying humidity and contamination conditions. Integrated into a smart mask, the ASRS enables continuous respiratory monitoring across diverse demographic and activity profiles [78]. Complementing this, a deep-learning-assisted on-mask sensor network constructed from spindle-knotted fibers achieves a high signal-to-noise ratio (51.2 dB), rapid response (0.28 s), and sensitivity of 0.46 V·kPa⁻¹. When coupled with a convolutional neural network, the system classifies respiratory patterns with 100% accuracy, offering a new paradigm for IoT-enabled adaptive respiratory monitoring [79].

Energy harvesting and motion tracking represent another major thrust in TENG research. Figure 7e shows a walking energy harvesting and self-powered tracking system based on flexible TENGs embedded in footwear and sports gear [80]. The system effectively converts gait-induced mechanical energy into electricity, supporting motion recognition and energy storage.

Figure 7. Representative TENG-based wearable systems for all-weather healthcare monitoring. (a) Acoustically enhanced stethoscope for ultrasensitive detection of cardiac sounds and murmurs, reprinted/adapted with permission from Ref. [74]. (b) Textile-based wireless biosensor for real-time pulse tracking with high sensitivity and durability, reprinted/adapted with permission from Ref. [75]. (c) Inhalation-driven vertical flutter TENG in gas masks for respiratory monitoring, gas detection, and self-powered alarms, reprinted/adapted with permission from Ref. [76]. (d) Smart wearable multimodal patches for heart rate, respiration, and activity monitoring without external power, reprinted/adapted with permission from Ref. [77]. (e) Walking-driven energy harvesting system in shoes for motion tracking and fall prevention, reprinted/adapted with permission from Ref. [80]. (f) Smart pillow with flexible TENG arrays for unobtrusive monitoring of head movement, posture, and sleep quality, reprinted/adapted with permission from Ref. [81]. (g) Eye-movement monitoring patch harvesting subtle ocular motions for self-powered visual behavior analysis, reprinted/adapted with permission from Ref. [82]. (h) Ultra-soft washable textile for continuous monitoring of ballistocardiograph, respiration, and posture during sleep, reprinted/adapted with permission from Ref. [83]. (i) Smart wearable multimodal patches for sleep monitoring, reprinted/adapted with permission from Ref. [77].

Figure 7. Representative TENG-based wearable systems for all-weather healthcare monitoring. (a) Acoustically enhanced stethoscope for ultrasensitive detection of cardiac sounds and murmurs, reprinted/adapted with permission from Ref. [74]. (b) Textile-based wireless biosensor for real-time pulse tracking with high sensitivity and durability, reprinted/adapted with permission from Ref. [75]. (c) Inhalation-driven vertical flutter TENG in gas masks for respiratory monitoring, gas detection, and self-powered alarms, reprinted/adapted with permission from Ref. [76]. (d) Smart wearable multimodal patches for heart rate, respiration, and activity monitoring without external power, reprinted/adapted with permission from Ref. [77]. (e) Walking-driven energy harvesting system in shoes for motion tracking and fall prevention, reprinted/adapted with permission from Ref. [80]. (f) Smart pillow with flexible TENG arrays for unobtrusive monitoring of head movement, posture, and sleep quality, reprinted/adapted with permission from Ref. [81]. (g) Eye-movement monitoring patch harvesting subtle ocular motions for self-powered visual behavior analysis, reprinted/adapted with permission from Ref. [82]. (h) Ultra-soft washable textile for continuous monitoring of ballistocardiograph, respiration, and posture during sleep, reprinted/adapted with permission from Ref. [83]. (i) Smart wearable multimodal patches for sleep monitoring, reprinted/adapted with permission from Ref. [77].

In the context of sleep health, several TENG-based platforms have been developed for nonobtrusive, long-term monitoring. Figure 7f shows a smart pillow integrated with breathable TENG arrays [81]. It translates subtle head movements into electrical signals, enabling precise assessment of sleep posture, turnover frequency, and head displacement. The system can reliably distinguish daily activities, such as fall detection, sports training, and outdoor monitoring. Similarly, Figure 7g [82] shows a triboelectric patch operating on Maxwell displacement current principles, which demonstrates utility in visual behavior analysis and cognitive studies. Figure 7h [83] illustrates a single-layered, ultra-soft, washable smart textile embedded with TENGs. It allows comprehensive monitoring of ballistocardiograph signals, respiration, and body posture during sleep while maintaining stable performance after repeated washing. These systems highlight the suitability of TENG-integrated textiles for daily sleep quality assessment and early disorder detection. Figure 7i [72] illustrates real-time monitoring of sleep state. When the user lies flat and breathes normally, the signal exhibits low amplitude and a prolonged response time. During sleep, breathing becomes shallower, the amplitude increases, and the response time decreases. In cases of deteriorated sleep quality or sleep apnea, both the amplitude and response time approach zero. Individual health monitoring and medical intervention can thus be guided based on variations in amplitude and response time. When the wearer turns to the right, the signal displays a peak, whereas turning from right to left produces a valley. This functionality is particularly valuable for health monitoring of infants, patients with attention deficit hyperactivity disorder, the elderly, or individuals with impaired consciousness.

Beyond sensing, multifunctional smart textiles have been engineered to integrate energy harvesting with additional practical features. A multipurpose textile (PTMT-TENG) combines efficient triboelectric energy harvesting, all-season switchable thermal management, and self-powered sensing. Its dual-mode phase-change material enables heating (+4.4 °C) and cooling (−3.8 °C) functions, while the structure achieves a power density of 8762 μW·m⁻², 325.8% higher than conventional TENGs, without compromising flexibility, breathability, or self-cleaning ability [84]. In another approach, a facile strategy produced a highly sensitive and water-resistant textile-based TENG (F-TENG) using waterborne polyurethane and polypyrrole layers. The resulting 3D microfiber architecture offers stable performance under 20–80% RH, generates up to 21 V in moist conditions, and exhibits antibacterial properties, making it suitable for wearable physiological monitoring and integrated therapeutic systems. Lastly, a self-powered pressure sensor system based on conductive silicone and patterned Ecoflex films was embedded into bicycle saddles. It converts biomechanical energy from pelvic and gait interactions into stable electrical signals across varying environmental conditions [85]. The extracted gait parameters support AI-assisted rehabilitation monitoring, offering a low-cost and scalable solution for smart healthcare applications.

Figure 7c presents an inhalation-driven self-powered system capable of simultaneously monitoring respiratory activity and detecting environmental gases [76]. This system highlights the applicability of TENG technology in industrial safety, environmental monitoring, and military operations. By transitioning from motion-driven to respiration-driven mechanisms, TENGs can efficiently harvest energy while performing functional sensing. This underscores their adaptability across diverse scenarios. A notable trend in TENG development is their integration into multifunctional, self-powered systems that combine energy harvesting, sensing, and communication within a single platform. For instance, motion-energy-harvesting TENGs enable continuous gait analysis and activity tracking, while inhalation-actuated vertical flutter TENGs (VF-TENGs) power gas sensors and respiratory monitors integrated into masks, thereby enhancing device autonomy, portability, and long-term usability. The shoe-sole TENG [80] uses elastic layers and micro structured interfaces to enhance energy capture without compromising comfort. Similarly, the VF-TENG employs highly elastic, low-friction films with optimized electrode spacing to generate high electrical output under low-frequency respiration. These designs improve not only efficiency but also signal stability and reproducibility, supporting long-term operation in health monitoring and protective applications.

Further expanding the functionality of self-powered wearables, a breathable and stretchable triboelectric liquid-metal e-skin has been developed, capable of harvesting energy from both biomechanical motion and electromagnetic pollution [86]. It operates via triboelectric (±2.3 μA, 205.6 V) and inductive (±1.7 μA, ±9.3 V) mechanisms, enabling continuous physiological monitoring across multiple body regions. This device represents a significant advance in multifunctional, energy-autonomous epidermal sensors. A transparent, conductive gelatin-based organohydrogel (GNOH) exhibits high stretchability (300%), conductivity (1.6 S/m), and freeze-tolerance (−20 °C) [87]. The resulting TENG functions effectively under extreme conditions, harvesting biomechanical energy and acting as a self-powered human–machine interface, demonstrating its potential in harsh-environment applications. Progress in energy harvesting has been further leveraged in health-focused applications through integrated self-powered sweat sensors, which demonstrate how energy harvesters convert biomechanical, thermal, or biochemical energy into electricity to drive sensing and communication, paving the way for fully autonomous health monitoring [88]. The communication is primarily Bluetooth Low Energy (BLE), chosen for its low power consumption suitable for energy-harvesting operation. To address environmental stability, a humidity-resistant TENG was developed using MoS₂-encapsulated SiO₂ nanoparticles, maintaining over 70% of its charge output after 25 h of exposure to 99% RH [89]. This stability supports reliable gas sensing in highly humid conditions, addressing a key challenge in field-deployable TENGs. In addition, a respiratory-powered mask incorporating a TENG-textile with a Ti₃C₂T_x/PANI NH₃ sensor delivers self-powered ammonia detection without external energy input [90], demonstrating practical applicability in food safety, environmental health, and non-invasive diagnostics. Together, these studies reflect a coherent evolution toward fully integrated, self-powered systems that combine advanced materials, environmental robustness, and multifunctional sensing for real-world health and monitoring applications.

The field of TENGs has evolved significantly since its initial demonstration. This pioneering work introduced a fundamental TENG architecture employing a freestanding triboelectric layer sliding between stationary electrodes. This design established the basis for non-contact energy harvesting through electrostatic induction [91]. The non-contact operation mode proved crucial for enhancing device durability and energy conversion efficiency, addressing early challenges associated with mechanical wear and energy loss. Building upon this foundation, researchers overcame the directional limitations of conventional TENGs by developing a biomimetic, fish-scale-inspired architecture featuring curved periodic electrodes. This design enabled omnidirectional energy harvesting and expanded applications beyond unidirectional motions, representing a key advancement in adapting TENG technology to practical, multidirectional mechanical inputs [92].

Another significant progression was the development of conformable devices, where TENGs were integrated with stretchable electronics, achieving approximately 800% stretchability. Importantly, they retained their dual functions as energy harvesters and sensors [93]. This work bridged the gap between rigid energy harvesters and skin-conformable wearable systems, enabling continuous health monitoring. To further enhance system integration, TENG and piezoelectric generator (PEG) technologies were combined, resulting in an intelligent hybrid system [94]. The synergistic operation—TENG for motion detection and PEG for energy harvesting—addressed critical power management challenges, particularly the trade-off between device functionality and power consumption in wearable electronics.

Material advancements have played a pivotal role in overcoming environmental limitations. In particular, researchers introduced novel eutectogel electrodes with exceptional mechanical robustness and self-healing capabilities [95]. The material demonstrated operational stability across extreme temperatures (−40 °C to 100 °C) and maintained performance after mechanical damage, representing a breakthrough for applications in harsh environments. Complementing these material developments, hybrid approaches employing ion-conductive hydrogel electrodes were explored. The integration of an AC dielectric elastomer generator with electret nanogenerator technology enabled approximately 860% stretchability and rapid charge response, addressing the challenge of energy harvesting under complex multidirectional motions [96]. Beyond conventional mechanical energy harvesting, a PVDF-based composite driven by evaporation enabled continuous power generation, independent of mechanical motion, thereby broadening the scope of environmental energy harvesting [97]. For specific biomedical applications, specialized ion hydrogel-based sensors with high sensitivity (0.2 mN detection limit) and rapid response (1.03 ms) were developed [98]. This work effectively translated flexible energy harvesting principles into practical medical monitoring solutions, particularly for musculoskeletal assessment and rehabilitation.

In all-weather monitoring, hybrid materials such as ion-conductive hydrogels, and organohydrogels deliver environmental stability, stretchability, and multimodal sensing. Textile-based TENGs integrate fiber morphology and surface patterning for breathable, washable, and self-powered operation. The synergy of material composition, hierarchical structure, and flexible design ensures long-term reliability, high sensitivity, and multifunctionality, enabling continuous health assessment under diverse environmental conditions.

For energy harvesting, triboelectric liquid-metal e-skins, gelatin-based organohydrogels, and moisture-resistant composites combine high stretchability, conductivity, and structural robustness to convert biomechanical, thermal, and chemical energy into electricity. Optimized multilayer architectures and micro-structured interfaces further enhance output efficiency and stability. This demonstrates that material innovation, coupled with strategic structural engineering, is essential for achieving fully integrated, self-powered wearable systems capable of reliable energy harvesting and real-time physiological sensing.

Across wearable TENG-based health monitoring and therapeutic systems, material selection emerges as a critical determinant of device performance, durability, and functionality. Fiber-based polymers and conductive fibers provide high stretchability and surface tunability for dual-modal sweat and motion sensing, while hydrogel- and organogel-based materials offer self-healing, mechanical compliance, and long-term operational stability. Nanohybrid layers (e.g., SnS₂/rGO) enhance surface area and conductivity, improving sensitivity for humidity and respiratory monitoring, whereas cellulose aerogels and hierarchical nanocellulose architectures boost triboelectric output, strain tolerance, and breathability for multimodal detection. Elastomeric rubbers such as BIIR and perovskite-filled composites achieve high surface charge density, mechanical robustness, and energy harvesting efficiency for posture and gait analysis. In all-weather applications, PVDF-based composites, ion-conductive hydrogels, and organohydrogels maintain performance under extreme environmental conditions while supporting energy harvesting, multimodal sensing, and wearable comfort. Collectively, these comparisons demonstrate that rational selection of triboelectric material, combined with micro/nano-scale surface engineering and hierarchical structural design, directly governs sensitivity, durability, multifunctionality, and real-world applicability. Integrating this material–structure–function perspective provides a clear framework for advancing next-generation, high-performance, self-powered wearable biosensors.

4. Conclusions and Outlook

In this work, we systematically reviewed the recent progress of triboelectric materials, encompassing their fundamental working modes, underlying mechanisms, bioinspired enhancement strategies, factors affecting charge density and output performance, and the development of next-generation devices. On this basis, we emphasized their diverse applications in active health monitoring, ranging from respiratory detection and motion tracking to all-weather physiological monitoring and fully self-powered energy harvesting. Notably, triboelectric materials exhibit not only excellent performance but also unique functionalities, such as intrinsic self-healing, which enables damaged devices to spontaneously restore both structural integrity and electrical properties at room temperature. This property significantly extends service lifetimes and addresses the fragility issues faced by conventional flexible sensors. Furthermore, the integration of triboelectric units with sensors, data processors, and wireless communication modules has propelled their evolution from simple mechanical–electrical converters toward intelligent, fully self-powered systems. Together, these advancements lay a strong foundation for future wearable biosensing platforms in sports monitoring, clinical diagnosis, rehabilitation, and public health protection.

Despite these achievements, several critical challenges remain: (i) Charge generation and stability: Achieving high and stable surface charge density remains central to device performance. However, the observed “mosaic” charge distribution challenges homogenization models, while the ultrafast charge-generation dynamics during contact–separation remain difficult to capture. Predictive models and advanced in situ characterization are urgently needed. (ii) Signal multiplexing: Balancing energy harvesting and sensing introduces inevitable trade-offs. Structural innovations and material engineering are required to optimize multifunctionality without compromising accuracy. (iii) Application adaptability: Human motion and environmental fluctuations introduce noise and degrade signal reliability. Robust structures, adaptive algorithms, and resilient designs are essential to ensure long-term stability. (iv) Wearability and biocompatibility: Daily use requires improved comfort, breathability, and skin compatibility, which should be prioritized in future designs. (v) System-level integration: Developing multimodal monitoring platforms requires the seamless integration of sensing, processing, and communication modules, supported by optimized architectures, low power consumption, and secure data management. Stable wireless connection, reliable inter-module data synchronization, and compatibility with existing smart devices are essential for practical wearable applications. Although low-power IC modules are already available in the market or in existing wearables, further optimization is needed to meet the high-precision requirements of multifunctional energy harvesting and sensing.

Recent advances in healthcare applications further highlight both opportunities and limitations. Biochemical monitoring platforms (e.g., sweat and metabolite sensors) demonstrate high sensitivity and self-powered operation but still suffer from limited selectivity and stability in complex bio-fluids. Posture and gait monitoring systems show promise in rehabilitation and elderly care, though challenges remain in robustness and accuracy under mechanical and environmental perturbations. All-weather health monitoring, including textile-based sensors and wearable e-skins, expands the scope of TENGs toward multimodal, long-term applications; however, issues of energy sustainability, data management, and multimodal integration persist.

Looking forward, addressing application-specific gaps requires tailored solutions:

(i) Biochemical monitoring: Molecularly engineered recognition layers, microfluidic sampling, and built-in calibration standards can enhance selectivity and reproducibility. (ii) Posture and gait monitoring: Bio-inspired flexible architectures, fatigue-resistant elastomers, dense sensor arrays, and lightweight machine-learning processors can improve robustness and classification accuracy. (iii) All-weather monitoring: Hybrid energy harvesting, low-power wireless protocols, and edge analytics will help achieve energy-efficient, multimodal, context-aware health assessment.

In conclusion, triboelectric materials are rapidly transitioning from energy harvesters to multifunctional, intelligent components that underpin the next generation of wearable health systems. Their self-powered sensing, seamless integration potential, and adaptability open vast opportunities for personalized healthcare, rehabilitation, and precision medicine. To fully realize this potential, future efforts must focus on regulating surface charges, enhancing robustness, improving long-term wearability, enabling multimodal data fusion, and achieving scalable manufacturing. Interdisciplinary advances across materials science, device engineering, data science, and system integration will be key to overcoming these challenges. With continued progress, triboelectric technologies are poised to play a transformative role in bridging sustainable energy solutions with intelligent biomedical applications.