A Self-Powered,Rechargeable, and Wearable Hydrogel Patch for Wireless Gas Detection with Extraordinary Performance

Flexible gas sensors play an indispensable role in diverse applications spanning from environmental monitoring to portable medical electronics. Full wearable gas monitoring system requires the collaborative support of high-performance sensors and miniaturized circuit module, whereas the realization of low power consumption and sustainable measurement is challenging. Here, a self-powered and reusable all-in-one NO₂ sensor is proposed by structurally and functionally coupling the sensor to the battery, with ultrahigh sensitivity (1.92%/ppb), linearity (R² = 0.999), ultralow theoretical detection limit (0.1 ppb), and humidity immunity. This can be attributed to the regulation of the gas reaction route at the molecular level. The addition of amphiphilic zinc trifluoromethanesulfonate (Zn(OTf)₂) enables the H₂O-poor inner Helmholtz layer to be constructed at the electrode–gel interface, thereby facilitating the direct charge transfer process of NO₂ here. The device is then combined with a well-designed miniaturized low-power circuit module with signal conditioning, processing and wireless transmission functions, which can be used as wearable electronics to realize early and remote warning of gas leakage. This study demonstrates a promising way to design a self-powered, sustainable, and flexible gas sensor with high performance and its corresponding wireless sensing system, providing new insight into the all-in-one system of gas detection.     

Stretchable Electrode Based on Laterally Combed Carbon Nanotubes for Wearable Energy Harvesting and Storage Devices

Carbon nanotubes (CNTs) are a promising material for use as a flexible electrode in wearable energy devices due to their electrical conductivity, soft mechanical properties, electrochemical activity, and large surface area. However, their electrical resistance is higher than that of metals, and deformations such as stretching can lead to deterioration of electrical performances. To address these issues, here a novel stretchable electrode based on laterally combed CNT networks is presented. The increased percolation between combed CNTs provides a high electrical conductivity even under mechanical deformations. Additional nickel electroplating and serpentine electrode designs increase conductivity and deformability further. The resulting stretchable electrode exhibits an excellent sheet resistance, which is comparable to conventional metal film electrodes. The resistance change is minimal even when stretched by ≈100%. Such high conductivity and deformability in addition to intrinsic electrochemically active property of CNTs enable high performance stretchable energy harvesting (wireless charging coil and triboelectric generator) and storage (lithium ion battery and supercapacitor) devices. Monolithic integration of these devices forms a wearable energy supply system, successfully demonstrating its potential as a novel soft power supply module for wearable electronics.     

Near-Infrared Light Triggered Self-Powered Mechano-Optical Communication System using Wearable Photodetector Textile

The merging of humans and machines depends on the contact sensor medium used. However, this contact interaction inevitably leads to mechanical loss. Photodetectors are cutting-edge tools in optical communication that use controlled lighting to achieve efficient signal conversion to drive mechano–optical communication systems and provide an innovative interface for the Internet of Things services. Here, a self-powered, non-contact mechano–optical communication system based on a wearable Te@TeSe photodetector textile is presented, which encodes near-infrared light to modulate robotic manipulator actions. The wearable Te@TeSe photodetector textile enhanced the photocurrent and responsivity by 400 times compared to a pristine Te nanowire (NW) array. The type II heterojunction of Te@TeSe NWs is proved by first-principles calculations and simulated, providing insights on photogenic carrier transmission in Te@TeSe NWs. This system shows the possibility of duplicate real-time execution of mechanical gestures in virtual environments and paves the way for advanced optical devices applied to information transmission and mechano–optical communication.     

Biocompatible Soft Fluidic Strain and Force Sensors for Wearable Devices

Fluidic soft sensors have been widely used in wearable devices for human motion capturing. However, thus far, the biocompatibility of the conductive liquid, the linearity of the sensing signal, and the hysteresis between the loading and release processes have limited the sensing quality as well as the applications of these sensors. In this paper, silicone based strain and force sensors composed of a novel biocompatible conductive liquid (potassium iodide and glycerol solution) are introduced. The strain sensors exhibit negligible hysteresis up to 5 Hz, with a gauge factor of 2.2 at 1 Hz. The force sensors feature a novel multifunctional layered structure, with microcylinder‐filled channels to achieve high linearity, low hysteresis (5.3% hysteresis at 1 Hz), and good sensitivity (100% resistance increase at a 5 N load). The sensors' gauge factors are stable at various temperatures and humidity levels. These biocompatible, low hysteresis, and high linearity sensors are promising for safe and reliable diagnostic devices, wearable motion capture, and compliant human–computer interfaces.     

Emerging Wearable Sensors for Plant Health Monitoring

Emerging plant diseases, caused by pathogens, pests, and climate change, are critical threats to not only the natural ecosystem but also human life. To mitigate crop loss due to various biotic and abiotic stresses, new sensor technologies to monitor plant health, predict, and track plant diseases in real time are desired. Wearable electronics have recently been developed for human health monitoring. However, the application of wearable electronics to agriculture and plant science is in its infancy. Wearable technologies mean that the sensors will be directly placed on the surfaces of plant organs such as leaves and stems. The sensors are designed to detect the status of plant health by profiling various trait biomarkers and microenvironmental parameters, transducing bio-signals to electric readout for data analytics. In this perspective, the recent progress in wearable plant sensors is summarized and they are categorized by the functionality, namely plant growth sensors, physiology, and microclimate sensors, chemical sensors, and multifunctional sensors. The design and mechanism of each type of wearable sensors are discussed and their applications to address the current challenges of precision agriculture are highlighted. Finally, challenges and perspectives for the future development of wearable plant sensors are presented.     

An Integrated Wearable Sweat Sensing Patch for Passive Continuous Analysis of Stress Biomarkers at Rest

Real-time monitoring of mental stress biomarkers in sweat provides the possibility to evaluate mental status in a precise manner. In general, wearable sweat sensors suffer from inconvenient sweat collection, low levels of diagnostic biomarkers in sweat, sophisticated signal processing, and challenges with data visualization. To overcome these challenges, herein an integrated wearable sweat-sensing patch for continuous analysis of stress biomarkers (cortisol, Mg²⁺, and pH) at rest is demonstrated. The sweat sensing patch comprised a microfluidic chip, a highly sensitive sensing platform, an on-site signal processing circuitry (SPCs), and a smartphone installed with a home-developed display software. The sweat collection at rest is realized using a microfluidic chip without perspiration assistance. A ternary composite electrode is designed to obtain good conductivity, high surface area, and massive reactive sites, thereby yielding excellent electrochemical performances and high sensitivity to trace stress biomarkers. The on-site SPC has the function of signal transduction, conditioning, processing, and wireless transmission. The detection results can be displayed on a smartphone through the software. This work represents a significant scientific and technological advancement toward indexing mental stress status and can be used as an innovative tool for psychological diagnosis.     

Self-Healable Triboelectric Nanogenerators: Marriage between Self-Healing Polymer Chemistry and Triboelectric Devices

Based on the triboelectrification and electrostatic induction coupling, triboelectric nanogenerators (TENGs) can convert mechanical energy into electrical energy, showing a promising potential in the fields of micro/nano energy and self-powered sensors applications. However, the devices are prone to malfunction due to fatigue and damage, limiting their development and applications. In this review, according to the working modes and operational malfunctions as well as the possible solutions, it is proposed that a robust TENG device can be constructed from three perspectives: self-healing friction layers, self-healing electrodes, and self-healing whole devices. Based on the structure, suitable environment, and self-healing materials, the design ideas and fabrication approaches of self-healing TENGs in recent years are summarized in detail. Finally, the development of self-healing TENGs in energy harvesting and self-powered sensors is outlined. It is the wish to provide insights and guidance for the application design of self-healing TENGs in the future.     

Flexible MXene-Based Composites for Wearable Devices

In recent decades, flexible and wearable devices have been extensively investigated due to their promising applications in portable mobile electronics and human motion monitoring. MXene, a novel growing family of 2D nanomaterials, demonstrates superiorities such as outstanding electrical conductivity, abundant terminal groups, unique layered-structure, large surface area, and hydrophilicity, making it to be a potential candidate material for flexible and wearable devices. Numerous pioneering works are devoted to develop flexible MXene-based composites with various functions and designed structures. Therefore, the latest progress of the flexible MXene-based composites for wearable devices is summarized in this review, focusing on the preparation strategies, working mechanisms, performances, and applications in sensors, supercapacitors, and electromagnetic interference shielding materials. Moreover, the current challenges and future outlooks are also discussed.     

Flexible Liquid-Based Continuous Direct-Current Tribovoltaic Generators Enable Self-Powered Multi-Modal Sensing

Flexible tribovoltaic direct-current (DC) generators are urgently expected by wearable applications. Traditional rigid contact-separation type tribovoltaic DC generators normally have non-ignorable friction loss and cannot sustain outstanding outputs. This hinders their serviceability in continuous motion scenarios. Here, flexible liquid-based DC generators (FLGs) with metal-liquid-semiconductor indium gallium zinc oxide (IGZO) stack structures are reported. The FLG with Pt/H₂O/IGZO structure delivers a peak short-circuit current density up to 2.3 µA cm⁻², a peak open-circuit voltage up to 620 mV, and a power density up to 0.1 µW cm⁻². The differences in the properties of different liquid–solid interfaces are studied by density functional theory, showing that the bond formation, charge-transfer-induced dipole electric field at the solid-liquid interface, and the built-in electric field are responsible for the generation and separation of electron-hole pairs to form continuous DC. The proposed FLG can keep excellent performance even after >5 × 10⁴ shaking cycles or exposing to ambient conditions for 30 days, showing extraordinary stability. Besides charging capacitors or driving LEDs, the FLG is further demonstrated to work for self-powered multifunctional sensing, enabling pressure, position-posture, or temperature detections. This design offers potential solutions and novel possibilities for next-generation self-powered wearable electronics.     

Self-Healing Titanium Dioxide Nanocapsules-Graphene/Multi-Branched Polyurethane Hybrid Flexible Film with Multifunctional Properties toward Wearable Electronics

The integration of self-healing capabilities into flexible electronics arouses extensive attention. The application of self-healing electronics with multifunctional properties in a variety of exceptional environments has been identified to be significantly challenging and not yet proven to be fully viable thus far. In the present study, the self-healing octadecane loaded titanium dioxide nanocapsules (OTNs)-graphene/multi-branched polyurethane (PU) hybrid flexible multifunctional film is successfully prepared. The prepared film exhibits a novel self-repair capability that consists of disulfide bonds in the leading chains for efficient self-healing of PU damage, as well as multiple amino groups in the branches for damage between OTNs-graphene and PU. Impacted by the constructed self-healing system and well-dispersed OTNs-graphene, the prepared flexible film demonstrates a prominent performance in piezoresistive sensing and a desirable outcome of ultraviolet protection properties, which can effectively prolong its service life, especially when used outdoors. Moreover, the film exhibits thermal insulating properties, capable of offering a suitable route for thermal protection of bio-integrated wearable electronic devices system. Thus, this self-healing multifunctional film is promising in wearable electronics, human–machine interaction, artificial intelligence devices, etc.     

Wearable Organic Electrochemical Transistor Array for Skin-Surface Electrocardiogram Mapping Above a Human Heart

Electrocardiogram (ECG) mapping can provide vital information in sports training and cardiac disease diagnosis. However, most electronic devices for monitoring ECG signals need to use multiple long wires, which limit their wearability and conformability in practical applications, while wearable ECG mapping based on integrated sensor arrays has been rarely reported. Herein, ultra-flexible organic electrochemical transistor (OECT) arrays used for wearable ECG mapping on the skin surface above a human heart are presented. QRS complexes of ECG signals at different recording distances and directions relative to the heart are obtained. Furthermore, the ECG signals are successfully analyzed by the devices before and after exercise, indicating potential applications in some sports training and fitness scenarios. The OECT arrays that can conveniently monitor spacial ECG signals in the heart region may find niche applications in wearable electronics and healthcare products in the future.     

Triboelectricity Based Self-Powered Digital Displacement Sensor for Aircraft Flight Actuation

The utilization of unmanned aerial vehicles (UAVs) is on the rise across various industries. In such a scenario, the issue of flight safety for these UAVs becomes increasingly paramount. Currently, UAVs exhibit shortcomings in flight attitude perception compared to more mature manned aircraft, especially concerning the position sensing of flight actuation, which poses significant safety risks. Mature position monitoring solutions for flight actuation used in manned aircraft cannot be directly integrated into systems of UAV due to compatibility issues. This necessitates the development of new position sensing technologies to address this challenge. Triboelectric nanogenerators, with their advantages of miniaturization, self-powering capabilities, and the ability to generate voltage-level electrical signals, are chosen to form a part of the position detection system for sensors in UAVs. In this study, a self-powered displacement sensor is developed that utilizes frictional charge separation signals. This sensor is specifically designed to monitor the position status of the flight actuators in UAV. With a compact volume of <11.1 cm³ and a weight of <9.5 g, this sensor is lightweight efficient and adaptable for practical applications.     

On‐Body Bioelectronics: Wearable Biofuel Cells for Bioenergy Harvesting and Self‐Powered Biosensing

The growing power demands of wearable electronic devices have stimulated the development of on‐body energy‐harvesting strategies. This article reviews the recent progress on rapidly emerging wearable biofuel cells (BFCs), along with related challenges and prospects. Advanced on‐body BFCs in various wearable platforms, e.g., textiles, patches, temporary tattoo, or contact lenses, enable attractive advantages for bioenergy harnessing and self‐powered biosensing. These noninvasive BFCs open up unique opportunities for utilizing bioenergy or monitoring biomarkers present in biofluids, e.g., sweat, saliva, interstitial fluid, and tears, toward new biomedical, fitness, or defense applications. However, the realization of effective wearable BFC requires high‐quality enzyme‐electronic interface with efficient enzymatic and electrochemical processes and mechanical flexibility. Understanding the kinetics and mechanisms involved in the electron transfer process, as well as enzyme immobilization techniques, is essential for efficient and stable bioenergy harvesting under diverse mechanical strains and changing operational conditions expected in different biofluids and in a variety of outdoor activities. These key challenges of wearable BFCs are discussed along with potential solutions and future prospects. Understanding these obstacles and opportunities is crucial for transforming traditional bench‐top BFCs to effective and successful wearable BFCs.     

Wearable Thermoelectric Generators for Body-Powered Devices

This paper presents a discussion on energy scavenging for wearable devices in conjunction with human body properties. Motivation, analysis of the relevant properties of the human body, and results of optimization of a thermopile and a thermoelectric generator for wearable and portable devices are presented. The theoretical limit for power generation on human beings is evaluated and confirmed by experimental results. The requirements for wearable thermopiles are summarized. The results allow certain conclusions to be drawn concerning directions for future development of body-powered devices.     

可穿戴设备领域的中国专利分析

随着谷歌、苹果、三星以及微软等科技巨头相继推出可穿戴设备,该领域正成为研发热点,作为未来最具发展潜力的产业之一,可穿戴设备的相关专利布局早已展开.基于在中国申请的专利文献样本数据,针对可穿戴设备领域的特点、历年的专利申请量、应用领域及技术组成、主要专利申请人等方面对可穿戴设备领域中国专利申请状况进行了分析研究,希望对国内相关企业的技术发展起到一定的作用.     

High Performance Bacterial Cellulose Organogel-Based Thermoelectrochemical Cells by Organic Solvent-Driven Crystallization for Body Heat Harvest and Self-Powered Wearable Strain Sensors

As a low-grade sustainable heat source, the human body provides a great driving force for converting heat into electric energy using thermoelectric materials, which can effectively power wearable electronics. However, the low thermoelectric conversion efficiency is not sufficient to achieve energy autonomy in the operation of wearable devices. Herein, wearable bacterial cellulose (BC) organogel-based thermoelectrochemical cells (TECs) are designed and prepared with K₄Fe(CN)₆/K₃Fe(CN)₆ as a redox couple. The addition of propylene glycol significantly improves the mechanical properties of the TECs and drives K₄Fe(CN)₆ to gradually crystallize, resulting in the concentration gradient of redox ions, which significantly enhanced the heat-to-electricity conversion efficiency (from 1.27 to 2.30 mV K⁻¹), proving that they are promising candidates for powering flexible and wearable devices in various application scenarios. The TECs are further assembled into self-powered strain sensors, which can detect the movement of the human body under various tensions and pressures in real time with high sensitivity. This indicates that the BC organogel-based TECs for self-powered strain sensors have great application potential in the wearable field.     

A Highly Stretchable Fiber‐Based Triboelectric Nanogenerator for Self‐Powered Wearable Electronics

The development of flexible and stretchable electronics has attracted intensive attention for their promising applications in next‐generation wearable functional devices. However, these stretchable devices that are made in a conventional planar format have largely hindered their development, especially in highly stretchable conditions. Herein, a novel type of highly stretchable, fiber‐based triboelectric nanogenerator (fiber‐like TENG) for power generation is developed. Owing to the advanced structural designs, including the fiber‐convolving fiber and the stretchable electrodes on elastic silicone rubber fiber, the fiber‐like TENG can be operated at stretching mode with high strains up to 70% and is demonstrated for a broad range of applications such as powering a commercial capacitor, LCD screen, digital watch/calculator, and self‐powered acceleration sensor. This work verifies the promising potential of a novel fiber‐based structure for both power generation and self‐powered sensing.     

一种上变频自供电无线传感器电源管理电路

电线周围的电磁场能量密度低,电磁换能器采集到的能量通常无法直接驱动无线传感器正常工作.论文采用上变频技术,设计了一种自供电电源管理电路来提高能量采集效率.由于电路的输出功率与品质因数成正比,且品质因数的大小与电路谐振电容的根号值成反比,因此通过提高电路的工作频率来减小谐振电容值,可以使高品质因数的电路产生更高的输出功率,进而增加能量采集效率.实验结果表明,该电路的最大能量采集效率是传统桥式整流电路的2.1倍.当电线中通过1A、50Hz的交流电时,电源管理电路最大采集功率为780μW,能量采集效率达到48.75%.当管理电路中超级电容能量积累达到一定程度,电容放电驱动无线传感器工作.