A monolithically integrated in-textile wristband for wireless epidermal biosensing

Wearable epidermal sensor patch with biomimetic microfluidic channels for fast and time-sequence monitoring of sweat glucose and lactate

Wearable sweat sensors enable non-invasive tracking and monitoring of human physiological information, which is expected to attract wide interest and rapid development in dietary health management and disease prevention. Unfortunately, sweat sensors are limited by rapid evaporation and low secretion rates of sweat. Herein, a sweat detection patch is proposed, which integrates bionic microchannels and multiparameter electrochemical sensors. The microfluidic channel (5°), which mimics ginkgo biloba veins, provided a 40 % higher flow rate compared to the normal channel (0°). Combined with burst pressure, the bionic channel enabled unidirectional transport of 6 μL sweat, effectively avoiding the mixing of old and new sweat. The electrochemical sensors possessed excellent specificity recognition, stability and durability, and have been used to detect substances in sweat, in particular to analyze changes in glucose concentration at different dietary intakes and changes in lactate metabolism after exercise. The rapid collection effect of the microchannels on trace sweat and the fast response of sensors have broad application prospects in real-time human health monitoring.

High-Resolution Patterning of Breathable Polymer Nanomesh via Double-Side UV Exposure for Fabricating Micropatterned Wearable Devices

Nanomesh electronics, renowned for their breathability and compatibility with long-term skin attachment, face significant challenges in achieving high-resolution micropatterning, which limits their applications in advanced devices. To address this, a method to fabricate durable, breathable, and highly conductive micropatterned nanomesh electrodes (MPNEs) with line widths as narrow as 10 μm was developed. Using a double-side exposure technique, precise patterning was achieved on a polyimide nanomesh substrate. Silver nanowires (AgNWs) were selectively deposited via vacuum filtration, ensuring optimal alignment for enhanced conductivity. The MPNEs exhibit excellent electrical performance, achieving a sheet resistance of 3.9 Ω sq-1 at an AgNW loading of 1.6 μg mm-2. They maintain consistent conductivity across various line widths and lengths, demonstrating high reproducibility. Mechanical testing confirmed exceptional durability under significant deformations, including bending, folding, and twisting. Furthermore, the porous structure remained breathable after AgNW deposition, preserving gas and moisture permeability. The versatility of MPNEs was demonstrated by fabricating intricate patterns such as interdigitated electrodes, multielectrode arrays, and coil antennas. These findings underscore the potential of MPNEs for advanced wearable electronics and multifunctional devices.

Metal-Organic Framework-Based Tribovoltaic Textile for Human Body Signal Monitoring

The pursuit of sustainable and portable direct current (DC) energy suppliers has ignited considerable interest in tribovoltaic nanogenerators (TVNGs), devices that harvest mechanical energy from the surrounding environment. However, the predominant focus in TVNG research has centered on rigid and silicon-based semiconductors that lack flexibility and are thus ill-suited for integration into common fabrics. Herein, a fully-textile TVNG with a simple design is introduced that enables the real-time monitoring of human physiological signals. The utilization of copper-benzenehexathiol (Cu-BHT), a conductive 2D metal-organic framework is proposed as a p-type semiconductor grown on fabric surfaces. The developed tribovoltaic textile (TVT) consists of Cu-BHT-modified cotton and metallic aluminum textile producing pure DC output due to self-rectification. With excellent flexibility and stability, Cu-BHT TVT is seamlessly integrated into textile-based accessories for continuous monitoring of human motion and respiration.

A photonic crystal-hydrogel sensor for the monitoring of potassium ions in sweat

Sweat contains abundant physiological information critical for health monitoring, making wearable sweat sensors increasingly popular in exercise and training surveillance. Most of the existing sensors are designed to measure physical parameters such as heart rate, blood pressure, and respiration, relying on electronic instruments for biochemical analysis of body fluids. In this study, we present a wearable hydrogel band integrated with a photonic crystal array, for visual, non-invasive and in situ analysis of sweat for sports practitioners. The hydrogel sensor, inspired by the biological properties of onions, demonstrates excellent skin adhesion for efficient sweat collection. This innovative design allows for the development of a simple, reliable, and low-cost sensor capable of detecting potassium ion concentrations and pH levels in sweat. Under optimized conditions, the developed sensor can respond to potassium ion concentrations ranging from 1 mM to 150 mM, with a pH response range of 3 to 9 for human sweat. The dynamic cycling tests of potassium ion concentration and pH in sweat demonstrated that this sensor can effectively monitor electrolyte balance and dehydration during outdoor exercise.

Emerging Multifunctional Wearable Sensors: Integrating Multimodal Sweat Analysis and Advanced Material Technologies for Next-Generation Health Monitoring

Sweat, a noninvasive and readily accessible biofluid, offers significant potential in health monitoring through its diverse biomarker profile, including electrolytes, metabolites, and hormones, which reflect physiological states in real time. Multimodal wearable sensors, integrating chemical, physical, and thermal sensing capabilities, have emerged as transformative tools for capturing these biomarkers alongside additional physiological signals. By combining advanced materials such as hydrogels, MXenes, and graphene with innovative structural designs, these sensors enable simultaneous monitoring of biomarkers (e.g., glucose, sodium, and cortisol) alongside parameters like movement and temperature. This Review systematically explores the classification and design of multimodal sensors, emphasizing their ability to address health monitoring challenges across applications including metabolic health management, stress detection, and hydration assessment. Key innovations in functional materials, such as conductive hydrogels and biomimetic structures, are discussed alongside challenges in signal integration, data processing, and power management. Additionally, advancements in self-powered systems and energy harvesting technologies have been highlighted as critical enablers for continuous, real-time monitoring. The Review concludes with a perspective on future directions, emphasizing the need for scalable manufacturing techniques, artificial intelligence integration, and standardized frameworks to enhance sensor functionality and adoption. Multimodal wearable sensors, by seamlessly integrating health data into daily life, hold the promise of transforming personalized healthcare, enabling proactive management of health and wellness through noninvasive, comprehensive, and real-time monitoring.

Motion-unrestricted dynamic electrocardiogram system utilizing imperceptible electronics

Electrocardiogram (ECG) plays a vital role in the prevention, diagnosis, and prognosis of cardiovascular diseases (CVDs). However, the lack of a user-friendly and accurate long-term dynamic electrocardiogram (DCG) device in motion has made it challenging to perform many daily cardiovascular risk screenings and assessments, such as sudden cardiac arrest, resulting in additional economic burdens on society. Here, we present a motion-unrestricted dynamic electrocardiogram (MU-DCG) system, which employs skin-conformal, imperceptible electronics for long-term, comfortable, and accurate 12-lead DCG monitoring. To facilitate assembly for use on the skin, the MU-DCG system features a pressure-activated flexible skin socket for stably soft-connecting the on-skin soft module and the off-skin stiff module during dynamic movements. Crucially, blinded cardiologist evaluations confirm minimal motion artifacts in MU-DCG-acquired ECG signals. Our results demonstrate that the MU-DCG system, with large-area, ultra-thin on-skin electrodes/leads, and an off-skin module, accomplishes anti-motion interference acquisition and in-situ analysis while retaining wearing imperceptibility.

Nanotechnology-Based Wearable Electrochemical Biosensor for Disease Diagnosis

Recently, flexible electronics have significantly transformed information and communications technology (ICT). In particular, wearable devices, via integration with attachable biosensors, have driven the development of new types of biosensors and diagnostic devices for point-of-care testing (POCT). Moreover, wearable electrochemical biosensors can be applied to diagnose diseases in real time based on the synergistic effect generated from the incorporation of the electrochemical technique. Besides, to improve the sensitivity of electrochemical biosensors while retaining their wearability, novel nanomaterials and nanotechnologies have been introduced. In this review, recent studies on nanotechnology-based wearable electrochemical biosensors for accurate disease diagnosis are discussed. First, widely used techniques for developing flexible electrodes, including nanolithography- and nano/microneedle-based patches, are presented. Next, the latest studies on developing wearable electrochemical biosensors for the diagnosis of diseases such as diabetes and dermatitis are discussed by categorizing the biosensors into nanolithography- and nano/microneedle-based categories. Finally, this review explores the latest research trends on the application of nanotechnology-enabled nanopatterning and nano/microneedle technologies to electrochemical wearable biosensors. This review suggests novel approaches and methods for developing wearable electrochemical biosensors for real-time disease diagnosis under POCT applications.

Biomaterials for reliable wearable health monitoring: Applications in skin and eye integration

Recent advancements in biomaterials have significantly impacted wearable health monitoring, creating opportunities for personalized and non-invasive health assessments. These developments address the growing demand for customized healthcare solutions. Durability is a critical factor for biomaterials in wearable applications, as they must withstand diverse wearing conditions effectively. Therefore, there is a heightened focus on developing biomaterials that maintain robust and stable functionalities, essential for advancing wearable sensing technologies. This review examines the biomaterials used in wearable sensors, specifically those interfaced with human skin and eyes, highlighting essential strategies for achieving long-lasting and stable performance. We specifically discuss three main categories of biomaterials-hydrogels, fibers, and hybrid materials-each offering distinct properties ideal for use in durable wearable health monitoring systems. Moreover, we delve into the latest advancements in biomaterial-based sensors, which hold the potential to facilitate early disease detection, preventative interventions, and tailored healthcare approaches. We also address ongoing challenges and suggest future directions for research on material-based wearable sensors to encourage continuous innovation in this dynamic field.

BSA/PEI/GOD modified cellulose nanocrystals for construction of hydrogel-based flexible glucose sensors for sweat detection

With the miniaturization, integration and intelligence of sweat electrochemical sensor technology, hydrogel flexible sensors have demonstrated immense potential in the field of real-time and non-invasive personal health monitoring. However, it remains a challenge to integrate excellent mechanical properties, self-healing properties, and electrochemical sensing capabilities into the preparation of hydrogel-based flexible sensors. The utilization of CBPG (cellulose nanocrystals (CNCs)@bovine serum albumin (BSA)@polyethyleneimine (PEI) glucose oxidase (GOD) nanomaterial) as both an enhancing phase and sensor probe within a hydrogel matrix, with poly(vinyl alcohol) (PVA) serving as the primary network constituent, has been proposed as a non-invasive technique for monitoring trace glucose levels in sweat. In this study, BSA was initially attached to CNCs through electrostatic interactions. To further boost the surface active sites of the nanomaterial (CNCs@BSA), PEI was grafted onto the nanomaterial surface. The resulting CNC@BSA@PEI nanomaterials were then used as carriers for GOD. The prepared hydrogel exhibited good self-healing properties (87.5%) and excellent breaking strength (0.8 MPa), effectively converting glucose stimulation in human sweat into electrical output. The sensor had a detection range of 1.0-100.0 μM and a detection limit as low as 0.9 μM. Due to its ability to specifically recognize trace glucose levels in sweat, the CBPG-PVA sensor can perform highly selective, flexible, and reliable real-time monitoring of human sweat, offering significant potential for wearable biofluid monitoring in personalized health applications.

Epidermal secretion-purified biosensing patch with hydrogel sebum filtering membrane and unidirectional flow microfluidic channels

The development of biosensing electronics for real-time sweat analysis has attracted increasing research interest due to their promising applications for non-invasive health monitoring. However, one of the critical challenges lies in the sebum interference that largely limits the sensing reliability in practical scenarios. Herein, we report a flexible epidermal secretion-purified biosensing patch with a hydrogel filtering membrane that can effectively eliminate the impact of sebum and sebum-soluble substances. The as-prepared sebum filtering membranes feature a dual-layer sebum-resistant structure based on the poly(hydroxyethyl methacrylate) hydrogel functionalized with nano-brush structured poly(sulfobetaine) to eliminate interferences and provide self-cleaning capability. Furthermore, the unidirectional flow microfluidic channels design based on the Tesla valve was incorporated into the biosensing patch to prevent external sebum contamination and allow effective sweat refreshing for reliable sensing. By seamlessly combining these components, the epidermal secretion-purified biosensing patch enables continuous monitoring of sweat uric acid, pH, and sodium ions with significantly improved accuracy of up to 12 %. The proposed strategy for enhanced sweat sensing reliability without sebum interference shows desirable compatibility for different types of biosensors and would inspire the advances of flexible and wearable devices for non-invasive healthcare.

Hydrogen-Bonded Organic Framework Films Integrated with Wavy Structured Design for Wearable Bioelectronics

The integration of hydrogen-bonded organic frameworks (HOFs) with flexible electronic technologies offers a promising strategy for monitoring detailed health information, owing to their inherent porosity, excellent biocompatibility, and tunable catalytic capabilities. However, their application in wearable and real-time health monitoring remains largely unexplored, primarily due to the mechanical mismatch between the traditionally fragile HOFs particles and the softness of human skin. Herein, this study demonstrates an epidermal biosensor that maintains reliable sensing capability even under extreme deformation and complex environmental conditions by integrating HOFs films with wavy bioelectrodes. This wearable biosensor demonstrates ultrasensitive detection capabilities, with a limit of detection of 49.64 nM, and accurately measures nutritional content in sweat while conforming to curved skin surfaces. The sensor's performance is comparable to those obtained using high-performance liquid chromatography (HPLC). More strikingly, scratched HOFs films can be regenerated through a simple solvent rinsing process, enabling their reuse in the fabrication of new biosensors and offering a significant advantage over conventional sensing materials. This work has the potential to inspire the development of more flexible electronic devices, leveraging the structural adaptability and diversity of HOFs for personalized healthcare applications and real-time health monitoring.

Olfactory-Inspired Separation-Sensing Nanochannel-Based Electronics for Wireless Sweat Monitoring

Human sweat has the potential to be sufficiently utilized for noninvasive monitoring. Given the complexity of sweat secretion, the sensitivity and selectivity of sweat monitoring should be further improved. Here, we developed an olfactory-inspired separation-sensing nanochannel-based electronic for sensitive and selective sweat monitoring, which was simultaneously endowed with interferent separation and target detection performances. The special separation-sensing strategy imparts functional composite membranes with a high sensitivity of 113 mV dec-1 for potassium detection. The excellent mechanical properties and conformability of the Kevlar aramid nanofiber layer bring well-wearing performances to realize continuous wireless sweat monitoring. The recognition between functional molecules and target ions is proved at the molecular level in detail in the article. The replacement of functional molecules proves the universality of the strategy for performance enhancement in intricate biofluid analysis systems.

Advancements in Passive Wireless Sensing Systems in Monitoring Harsh Environment and Healthcare Applications

Recent advancements in passive wireless sensor technology have significantly extended the application scope of sensing, particularly in challenging environments for monitoring industry and healthcare applications. These systems are equipped with battery-free operation, wireless connectivity, and are designed to be both miniaturized and lightweight. Such features enable the safe, real-time monitoring of industrial environments and support high-precision physiological measurements in confined internal body spaces and on wearable epidermal devices. Despite the exploration into diverse application environments, the development of a systematic and comprehensive research framework for system architecture remains elusive, which hampers further optimization of these systems. This review, therefore, begins with an examination of application scenarios, progresses to evaluate current system architectures, and discusses the function of each component-specifically, the passive sensor module, the wireless communication model, and the readout module-within the context of key implementations in target sensing systems. Furthermore, we present case studies that demonstrate the feasibility of proposed classified components for sensing scenarios, derived from this systematic approach. By outlining a research trajectory for the application of passive wireless systems in sensing technologies, this paper aims to establish a foundation for more advanced, user-friendly applications.

Multifunctional Porous Soft Bioelectronics

Soft bioelectronics, seamlessly interfacing with the human body to enable both recording and modulation of curvilinear biological tissues and organs, have significantly driven fields such as digital healthcare, human-machine interfaces, and robotics. Nonetheless, intractable challenges persist due to the onerous demand for imperceptible, burden-free, and user-centric comfortable bioelectronics. Porous soft bioelectronics is a new way to a library of imperceptible bioelectronic systems, that form natural interfaces with the human body. In this review, we provide an overview of the development and recent advances in multifunctional porous engineered soft bioelectronics, aiming to bridge the gap between living biotic and stiff abiotic systems. We first discuss strategies for fabricating porous, soft, and stretchable bioelectronic materials, emphasizing the concept of materials-level porous engineering for breathable and imperceptible bioelectronics. Next, we summarize wearable bioelectronics devices and multimodal systems with porous configurations designed for on-skin healthcare applications. Moving beneath the skin, we discuss implantable devices and systems enabled by porous bioelectronics with tissue-like compliance. Finally, existing challenges and translational gaps are also proposed to usher further research efforts towards realizing practical and clinical applications of porous bioelectronic systems; thus, revolutionizing conventional healthcare and medical practices and opening up unprecedented opportunities for long-term, imperceptible, non-invasive, and human-centric healthcare networks.

Ammonium Sensing Patch with Ultrawide Linear Range and Eliminated Interference for Universal Body Fluids Analysis

Ammonium level in body fluids serves as one of the critical biomarkers for healthcare, especially those relative to liver diseases. The continuous and real-time monitoring in both invasive and non-invasive manners is highly desired, while the ammonium concentrations vary largely in different body fluids. Besides, the sensing reliability based on ion-selective biosensors can be significantly interfered by potassium ions. To tackle these challenges, a flexible and biocompatible sensing patch for wireless ammonium level sensing was reported with an ultrawide linear range for universal body fluids including blood, tears, saliva, sweat and urine. The as-prepared biocompatible sensors deliver a reliable sensitivity of 58.7 mV decade-1 in the range of 1-100 mM and a desirable selectivity coefficient of 0.11 in the interference of potassium ions, attributed to the cross-calibration within the sensors array. The sensor's biocompatibility was validated by the cell growth on the sensor surface (> 80%), hemolysis rates (< 5%), negligible cellular inflammatory responses and weight changes of the mice with implanted sensors. Such biocompatible sensors with ultrawide linear range and desirable selectivity open up new possibility of highly compatible biomarker analysis via different body fluids in versatile approaches.

Fully integrated microneedle biosensor array for wearable multiplexed fitness biomarkers monitoring

Fitness monitoring has become increasingly important in modern lifestyles; the current fitness monitoring always relies on physical sensors, making it challenging to detect pertinent issues at a deeper level when exercising. Here, we report a fully integrated wearable microneedle sensor that simultaneously measures fitness related biomarkers (e.g., glucose, lactate, and alcohol) during physical exercise. Such a sensor integrates a biocompatible 3D-printed microneedle array that can comfortably access skin interstitial fluid and a small circuit for signal processing and calibration, and wireless communication. The microneedle array features good biocompatibility and highly sensitive biochemical sensors that can detect even the slightest variations within the biomarkers of this fluid. On-body experimental results indicate that such a sensor can monitor fitness-related biomarkers across multiple subjects and support multi-day monitoring, with results showing a good correlation with commercial devices. The data was transmitted to a smartphone via Bluetooth and uploaded to cloud platforms for further health assessment. This study has the potential to boost intelligent wearable devices in sports health.

A Fully Printable and Integrated System with Long-Term Stability for Versatile and Multimodal Perspiration Tracking

Real-time and continuous monitoring of physiological status via noninvasive sweat sensing shows promise for personalized healthcare and fitness management. However, the largely varied perspiration rates in different body statuses introduce challenges for effective sweat collection and accurate sensing. Herein, a fully printable strategy was developed to realize fully integrated patches for wireless sensing of sweat biomarker levels and perspiration rates with desirable stability and versatility. The printable calcium sensors with modified ion-selective membranes displayed an ultrawide linear range of 0.1-100 mM and a long-term stability with minimized drift down to 0.083 mV/h for around 40 h. Moreover, the microfluidic channels in versatile configurations were capable of a minimum sweat rate monitoring of 0.5 μL/min and a large sweat storage volume of up to 200 μL. The as-proposed fully printable sensing platforms provide high compatibility for sensor integration to achieve versatile perspiration tracking and comprehensive health monitoring.

Nanomaterials for Flexible Neuromorphics

The quest to imbue machines with intelligence akin to that of humans, through the development of adaptable neuromorphic devices and the creation of artificial neural systems, has long stood as a pivotal goal in both scientific inquiry and industrial advancement. Recent advancements in flexible neuromorphic electronics primarily rely on nanomaterials and polymers owing to their inherent uniformity, superior mechanical and electrical capabilities, and versatile functionalities. However, this field is still in its nascent stage, necessitating continuous efforts in materials innovation and device/system design. Therefore, it is imperative to conduct an extensive and comprehensive analysis to summarize current progress. This review highlights the advancements and applications of flexible neuromorphics, involving inorganic nanomaterials (zero-/one-/two-dimensional, and heterostructure), carbon-based nanomaterials such as carbon nanotubes (CNTs) and graphene, and polymers. Additionally, a comprehensive comparison and summary of the structural compositions, design strategies, key performance, and significant applications of these devices are provided. Furthermore, the challenges and future directions pertaining to materials/devices/systems associated with flexible neuromorphics are also addressed. The aim of this review is to shed light on the rapidly growing field of flexible neuromorphics, attract experts from diverse disciplines (e.g., electronics, materials science, neurobiology), and foster further innovation for its accelerated development.

A Wearable Electrochemical Sensor Based on Single-Atom Pt Anchored on Activated NiCo-LDH/Ti3C2Tx for Real-Time Monitoring of Glucose

Wearable, noninvasive sweat sensors enable real-time monitoring of metabolites in human health management. However, the commercial enzyme-based and currently nonenzymatic glucose sensor represents sluggish glucose oxidation kinetics and a narrow sensing range. Rational design of sensitive materials is significant yet faces a huge challenge. Herein, we construct a single-atom Pt supported on NiCo-LDH/Ti3C2Tx heterostructures (Pt1-NiCo-LDH/Ti3C2Tx) as the nonenzymatic electrochemical glucose sensor sensitive materials for selective detection of glucose level in human sweat. The obtained Pt1-NiCo-LDH/Ti3C2Tx with improved structural stability and enhanced charge transfer efficiency shows a low oxidation peak potential of 0.49 V, high sensitivity of 506.6 μA mM-1 cm-2, a low detection limit of 0.035 μM, and long-term stability toward the glucose detection. The wearable sensor, coupled with a wireless transmission module and a signal processing chip, is used for real-time perspiration glucose monitoring during outdoor exercise. The result is comparable to that of high-performance liquid chromatography (HPLC). This research provides a new paradigm for designing a wearable nonenzymatic electrochemical glucose sensor, enabling noninvasive real-time monitoring of glucose concentrations in human sweat.

A Step Forward for Smart Clothes: Printed Fabric-Based Hybrid Electronics for Wearable Health Monitoring

Smart clothes equipped with flexible sensing systems provide a comfortable means to track health status in real time. Although these sensors are flexible and small, the core signal-processing units still rely on a conventional printed circuit board (PCB), making current health-monitoring devices bulky and inconvenient to wear. In this study, a printed fabric-based hybrid circuit was designed and prepared-with a series of characteristics, such as surface/sectional morphology, electrical properties, and stability-to study its reliability. Furthermore, to verify the function of the fabric-based circuit, simulations and measurements of the circuit, as well as the collection and processing of a normal adult's electrophysiological signals, were conducted. Under 10,000 stretching and bending cycles with a certain elongation and bending angle, the resistance remained 0.27 Ω/cm and 0.64 Ω/cm, respectively, demonstrating excellent conductivity and reliability. Additionally, the results of the simulation and experiment showed that the circuit can successfully amplify weak electrocardiogram (ECG) signals with a magnification of 1600 times with environmental filtering and 50 Hz of industrial frequency interference. This technology can monitor human electrophysiological signals, such as ECGs, electromyograms (EMGs), and joint motion, providing valuable practical guidance for the unobtrusive monitoring of smart clothes.

Gold Nanowire Sponge Electrochemistry for Permeable Wearable Sweat Analysis Comfortably and Wirelessly

Electrochemistry-based wearable and wireless sweat analysis is emerging as a promising noninvasive method for real-time health monitoring by tracking chemical and biological markers without the need for invasive blood sampling. It offers the potential to remotely monitor human sweat conditions in relation to metabolic health, stress, and electrolyte balance, which have implications for athletes, patients with chronic conditions, and individuals for the early detection and management of health issues. The state-of-the-art mainstream technology is dominated by the concept of a wearable microfluidic chip, typically based on elastomeric PDMS. While outstanding sensing performance can be realized, the design suffers from the poor permeability of PDMS, which could cause skin redness or irritation. Here, we introduce an omnidirectionally permeable, deformable, and wearable sweat analysis system based on gold nanowire sponges. We demonstrate the concept of all-in-one soft sponge electrochemistry, where the working, reference, and counter electrodes and electrolytes are all integrated within the sponge matrix. The intrinsic porosity of sponge in conjunction with vertically aligned gold nanowire electrodes gives rise to a high electrochemically active surface area of ∼67 cm2. Remarkably, this all-in-one sponge-based electrochemical system exhibited stable performance under a pressure of 10 kPa and 300% omnidirectional strain. The gold sponge biosensing electrodes could be sandwiched between two biocompatible sweat pads, which can serve as natural sweat collection and outflow layers. This naturally biocompatible and permeable platform can be integrated with wireless communication circuits, leading to a wireless sweat analysis system for the real-time monitoring of glucose, lactate, and pH during exercise.

Bipolar Textile Composite Electrodes Enabling Flexible Tandem Solid-State Lithium Metal Batteries

A majority of flexible and wearable electronics require high operational voltage that is conventionally achieved by serial connection of battery unit cells using external wires. However, this inevitably decreases the energy density of the battery module and may cause additional safety hazards. Herein, a bipolar textile composite electrode (BTCE) that enables internal tandem-stacking configuration to yield high-voltage (6 to 12 V class) solid-state lithium metal batteries (SSLMBs) is reported. BTCE is comprised of a nickel-coated poly(ethylene terephthalate) fabric (NiPET) core layer, a cathode coated on one side of the NiPET, and a Li metal anode coated on the other side of the NiPET. Stacking BTCEs with solid-state electrolytes alternatively leads to the extension of output voltage and decreased usage of inert package materials, which in turn significantly boosts the energy density of the battery. More importantly, the BTCE-based SSLMB possesses remarkable capacity retention per cycle of over 99.98% over cycling. The composite structure of BTCE also enables outstanding flexibility; the battery keeps stable charge/discharge characteristics over thousands of bending and folding. BTCE shows great promise for future safe, high-energy-density, and flexible SSLMBs for a wide range of flexible and wearable electronics.

Bioelectronics for electrical stimulation: materials, devices and biomedical applications

Bioelectronics is a hot research topic, yet an important tool, as it facilitates the creation of advanced medical devices that interact with biological systems to effectively diagnose, monitor and treat a broad spectrum of health conditions. Electrical stimulation (ES) is a pivotal technique in bioelectronics, offering a precise, non-pharmacological means to modulate and control biological processes across molecular, cellular, tissue, and organ levels. This method holds the potential to restore or enhance physiological functions compromised by diseases or injuries by integrating sophisticated electrical signals, device interfaces, and designs tailored to specific biological mechanisms. This review explains the mechanisms by which ES influences cellular behaviors, introduces the essential stimulation principles, discusses the performance requirements for optimal ES systems, and highlights the representative applications. From this review, we can realize the potential of ES based bioelectronics in therapy, regenerative medicine and rehabilitation engineering technologies, ranging from tissue engineering to neurological technologies, and the modulation of cardiovascular and cognitive functions. This review underscores the versatility of ES in various biomedical contexts and emphasizes the need to adapt to complex biological and clinical landscapes it addresses.

Breathable Wearable Smartsensors Deriving from Interface Self-Assembled Film for Tracking l-Cysteine

The advent of wearable sensors heralds a transformation in the continuous, noninvasive analysis of biomarkers critical for disease diagnosis and fitness management. Yet, their advancement is hindered by the functional challenges affiliated with their active sensing analysis layer. Predominantly due to suboptimal intrinsic material properties and inconsistent dispersion leading to aggregation, thus compromising sensor repeatability and performance. Herein, an innovative approach to the functionalization of wearable electrochemical sensors was introduced, specifically addressing these limitations. The method involves a proton-induced self-assembly technique at the organic-water (O/W) interface, facilitating the generation of biomarker-responsive films. This research offers flexible, breathable sensor capable of real-time precision tracking l-cysteine (l-Cys) precision tracking. Utilizing an activation mechanism for Prussian blue nanoparticles by hydrogen peroxide, the catalytic core exhibits a specific response to l-Cys. The implications of this study refine the fabrication of film-based analysis electrodes for wearable sensing applications and the broader utilization of two-dimensional materials in functional-specific response films. Findings illuminate the feasibility of this novel strategy for precise biomarker tracking and extend to pave the way for constructing high-performance electrocatalytic analytical interfaces.

Designs and Applications for the Multimodal Flexible Hybrid Epidermal Electronic Systems

Research on the flexible hybrid epidermal electronic system (FHEES) has attracted considerable attention due to its potential applications in human-machine interaction and healthcare. Through material and structural innovations, FHEES combines the advantages of traditional stiff electronic devices and flexible electronic technology, enabling it to be worn conformally on the skin while retaining complex system functionality. FHEESs use multimodal sensing to enhance the identification accuracy of the wearer's motion modes, intentions, or health status, thus realizing more comprehensive physiological signal acquisition. However, the heterogeneous integration of soft and stiff components makes balancing comfort and performance in designing and implementing multimodal FHEESs challenging. Herein, multimodal FHEESs are first introduced in 2 types based on their different system structure: all-in-one and assembled, reflecting totally different heterogeneous integration strategies. Characteristics and the key design issues (such as interconnect design, interface strategy, substrate selection, etc.) of the 2 multimodal FHEESs are emphasized. Besides, the applications and advantages of the 2 multimodal FHEESs in recent research have been presented, with a focus on the control and medical fields. Finally, the prospects and challenges of the multimodal FHEES are discussed.

Electrostatic Smart Textiles for Braille-To-Speech Translation

A wearable Braille-to-speech translation system is of great importance for providing auditory feedback in assisting blind people and people with speech impairment. However, previous reported Braille-to-speech translation systems still need to be improved in terms of comfortability or integration. Here, a Braille-to-speech translation system that uses dual-functional electrostatic transducers which are made of fabric-based materials and can be integrated into textiles is reported. Based on electrostatic induction, the electrostatic transducer can either serve as a tactile sensor or a loudspeaker with the same design. The proposed electrostatic transducers have excellent output performances, mechanical robustness, and working stability. By combining the devices with machine learning algorithms, it is possible to translate the Braille alphabet and 40 commonly used words (extensible) into speech with an accuracy of 99.09% and 97.08%, respectively. This work demonstrates a new approach for further developments of advanced assistive technology toward improving the lives of disabled people.

Printable and flexible integrated sensing systems for wireless healthcare

The rapid development of wearable sensing devices and artificial intelligence has enabled portable and wireless tracking of human health, fulfilling the promise of digitalized healthcare applications. To achieve versatile design and integration of multi-functional modules including sensors and data transmission units onto various flexible platforms, printable technologies emerged as some of the most promising strategies. This review first introduces the commonly utilized printing technologies, followed by discussion of the printable ink formulations and flexible substrates to ensure reliable device fabrication and system integration. The advances of printable sensors for body status monitoring are then discussed. Moreover, the integration of wireless data transmission via printable approaches is also presented. Finally, the challenges in achieving printable sensing devices and wireless integrated systems with competitive performances are considered, so as to realize their practical applications for personalized healthcare.

Porous Conductive Textiles for Wearable Electronics

Over the years, researchers have made significant strides in the development of novel flexible/stretchable and conductive materials, enabling the creation of cutting-edge electronic devices for wearable applications. Among these, porous conductive textiles (PCTs) have emerged as an ideal material platform for wearable electronics, owing to their light weight, flexibility, permeability, and wearing comfort. This Review aims to present a comprehensive overview of the progress and state of the art of utilizing PCTs for the design and fabrication of a wide variety of wearable electronic devices and their integrated wearable systems. To begin with, we elucidate how PCTs revolutionize the form factors of wearable electronics. We then discuss the preparation strategies of PCTs, in terms of the raw materials, fabrication processes, and key properties. Afterward, we provide detailed illustrations of how PCTs are used as basic building blocks to design and fabricate a wide variety of intrinsically flexible or stretchable devices, including sensors, actuators, therapeutic devices, energy-harvesting and storage devices, and displays. We further describe the techniques and strategies for wearable electronic systems either by hybridizing conventional off-the-shelf rigid electronic components with PCTs or by integrating multiple fibrous devices made of PCTs. Subsequently, we highlight some important wearable application scenarios in healthcare, sports and training, converging technologies, and professional specialists. At the end of the Review, we discuss the challenges and perspectives on future research directions and give overall conclusions. As the demand for more personalized and interconnected devices continues to grow, PCT-based wearables hold immense potential to redefine the landscape of wearable technology and reshape the way we live, work, and play.