Permeable superelastic liquid-metal fibre mat enables biocompatible and monolithic stretchable electronics

Multi-responsive and self-sensing flexible actuator based on MXene and cellulose nanofibers Janus film

Flexible actuators are widely used in soft robots, flexible electronics, and biomedicine. However, there still exists a significant challenge in fabricating flexible actuators with multi-response and self-sensing capabilities. In order to address this issue, a novel multi-responsive and self-sensing flexible actuator incorporating an MXene/cellulose nanofibers (MXene/CNF) Janus film was ingeniously developed. MXene/CNF Janus film was prepared using a layered filtration method. The MXene layer of the Janus film exhibits outstanding photothermal conversion properties as well as remarkable electrothermal conversion performance, while its CNF layer showcases excellent moisture absorption properties. As a result of the hydrogen bonding between MXene and CNF, the MXene/CNF Janus film exhibits excellent mechanical properties (Young's modulus of 3620.55 MPa). Using MXene as the printing solution, MXene/polyethylene (MPE) strain sensor with the function of self-sensing the deformation of the flexible actuator was prepared on the PE film by electrohydrodynamic (EHD) printing technology. The MXene/CNF Janus film was assembled with MPE film to fabricate a MXene/CNF-MPE smart flexible actuator with multi-responsive actuation capability and the self-sensing deformation function. Under a near-infrared light intensity of 250 mW/cm2, the fabricated actuator can achieve a bending curvature of 1.54 cm-1 within 6.8 s, and it reaches a bending curvature of 4.39 cm-1 within 28 s under a 4 V voltage. Moreover, during the process of environmental humidity changing from 50 % to 80 %, the fabricated actuator demonstrates a bending curvature of 1.81 cm-1. While responding to these multiple stimuli, the flexible actuator can self-sense the bending deformation through the resistance change of the MPE-based flexible strain sensor. Lastly, the flexible actuator demonstrates the possibilities in gesture recognition of bionic hand and bionic flytrap.

A high-performance photonic-ionic E-skin with synergistic electronic/optical sensing for motion tracking

The integration of visualization and electrical feedback in biomimetic electronic skin (E-skin) for real-time motion tracking has attracted significant attention in wearable electronics. To facilitate human-readable interactive feedback and improve the overall performance of E-skin, particularly regarding mechanical compliance, sensitivity, and stability, we propose a novel high-performance photonic-ionic skin (PI-skin) based on mechanochromic photonic ionogel. The PI-skin, prepared by incorporating aligned magnetic colloids into an ionogel matrix, integrates interactive structural coloration and electrical responses to external stimuli, achieving dual-mode precise motion recognition. Due to the enhanced hydrogen bonding and electrostatic interactions within the ionogel matrix, the PI-skin exhibits excellent mechanical properties (tensile strain >1000%), remarkable adhesive strength (peeling force >7 kPa), high sensitivity (gauge factor = 1.42 at straining 0%-300% and 2.71 at straining 300%-500%), rapid response time (120 ms), and exceptional mechanical compliance (>500 continuous cycles). More importantly, such PI-skin demonstrates ultrafast and highly accurate optical/electrical dual-signal motion detection, thereby facilitating posture correction during sitting and encoding of vocal cord vibrations during speech. We anticipate that this versatile PI-skin will possess substantial potential in the field of wearable electronics, and may inspire the design of next-generation E-skin for human-computer interaction and personalized healthcare applications.

Conformal, Substrate-Free Liquid Metal Electrode for Continuous Health Monitoring

Thin, skin-conformal soft electronics are ideal for seamless integration with the skin, enabling high-fidelity health monitoring and advanced human-machine interactions. However, achieving imperceptible and seamless adhesion with traditional materials and design approaches remains challenging as it is difficult to simultaneously meet the requirements of gas permeability, high conductivity, and conformability. In this work, we present a straightforward and efficient design for ultrathin, substrate-free, highly gas-permeable, and conductive liquid metal electrodes. These electrodes can be directly laminated onto human skin using water mist dissolution, facilitated by electrospun nanomeshes made from a poly(vinyl alcohol) and sodium dodecyl sulfate substrate. The electrodes have a thickness of 8.3 μm, a conductivity of 4.2 × 106 S m-1, and a gas permeability of 1283.8 ± 27.7 g m-2 day-1. A 24 h skin patch test demonstrated that the epidermal electrodes did not cause any skin irritation. Additionally, the electrodes exhibit excellent customizable patterning capabilities and recyclability. The electrodes successfully measure high-fidelity electrophysiological signals wirelessly, even during various daily activities such as sleep, work on the computer, and walking.

Liquid Metal-Tannic Acid-Modified Cotton Yarn Prepared with Twist-Assisted Deposition Technique for Textile Electronics

The past decade has witnessed the rapid growth of electronic textiles with a variety of textile-based smart devices being developed. However, the development of one-dimensional conductors that exhibit both excellent mechanical and electrical properties, while being compatible with conventional textile techniques, remains a challenge. Herein, a conductive cotton yarn was constructed using liquid metal as the conductive filler and tannic acid (TA) as the immobilizing linker via a twist-assisted deposition technique, in which eutectic gallium-indium alloy (EGaIn) droplets were effectively modified on cotton plies by using TA, followed by moderate twisting. By fully utilizing internal spaces between the adjacent fibers, the as-prepared EGaIn-TA-yarn exhibits high conductivity, with an average resistance of 11.20 Ω at a 10 cm length. When further wrapped with cotton fibers, the conductive yarn shows superior wash resistance, long-term stability, and excellent flexibility. It can withstand 25 washes, 3000 bending or twisting cycles, and 90 days of storage at ambient conditions without significant loss of conductivity. The cotton-wrapped EGaIn-TA-yarn could be used as a bendable, knottable, and sewable conductor to connect light-emitting diodes (LEDs) to power sources for lighting. This work could provide a simple, cost-effective approach to developing highly conductive yarns as promising candidates to replace traditional metal wires in textile electronics.

Meter-scale heterostructure printing for high-toughness fiber electrodes in intelligent digital apparel

Intelligent digital apparel, which integrates electronic functionalities into clothing, represents the future of healthcare and ubiquitous control in wearable devices. Realizing such apparel necessitates developing meter-scale conductive fibers with high toughness, conductivity, stable conductance under deformation, and mechanical durability. In this study, we present a heterostructure printing method capable of producing meter-scale (~50 m) biphasic conductive fibers that meet these criteria. Our approach involves encapsulating deformable liquid metal particles (LMPs) within a functionalized thermoplastic polyurethane matrix. This encapsulation induces in situ assembly of LMPs during fiber formation, creating a heterostructure that seamlessly integrates the matrix's durability with the LMPs' superior electrical performance. Unlike rigid conductive materials, deformable LMPs offer stretchability and toughness with a low gauge factor. Through precise twisting using an engineered annealing machine, multiple fiber strands are transformed into robust, electrically stable meter-scale electrodes. This advancement enhances their practicality in various intelligent digital apparel applications, such as stretchable displays, wearable healthcare systems, and digital controls.

Multifunctional Liquid-Metal Composites for Electromagnetic Communication and Attenuation

Efficient and reliable information transmission is crucial in the widespread use of electronic products and wireless communication. Additionally, it is vital to address the electromagnetic interference (EMI) and radiation that arise from the communication process. In particular, the emergence of flexible electronic products has posed new hurdles for EM functional materials with flexibility and high performance. Liquid metal (LM) is an innovative EM functional material that possesses both the conductivity of metals and the fluidity to reconfigure like a liquid. These characteristics paved the way for developing novel flexible electronic devices and products. This review provides an overview of the current status and future potential of LM-based EM functional materials. It highlights the latest progress in LM-based materials for applications such as EMI shielding, EM-wave absorption, and wireless communication (antennas). Finally, the primary obstacles of LM-based EM functional materials are discussed and revealed potential directions for their advancement. Overall, the current research on LM-based EM functional materials indicates that they have great potential to promote the development of EM functional materials, thus providing new possibilities for the advancement of flexible electronic products.

A Durable Metalgel Maintaining 3×106 S∙M‒1 Conductivity under 1 000 000 Stretching Cycles

Conductive elastomers are in high demand for emerging fields such as wearable electronics and soft robotics. However, it remains unavailable to realize the desired metal-level conductivity after extensive stretching cycles, which is a necessity for the above promising application. Here, a new material is presented that employs an elastic, homogeneous, and dense waterborne polyurethane network to immobilize the liquid metal continuum via electrostatic interactions. This new design enables the liquid metal continuum to deform synchronously and reversibly with the polymer network, preserving its conductive structure and significantly enhancing durability. The resulting durable metalgel exhibits conductivity of 3 × 106 S∙m-1, which remains stable after 1 000 000 stretching cycles. This work overcomes the performance limitations of current conductive elastomers and unlocks new opportunities for cutting-edge applications in wearable technology and robotics.

Cellulose Nanocrystal Stabilized Liquid Metal Pickering Emulsion as Photothermal and Conductive Direct-Writing Ink

Gallium-based liquid metal (LM) has attracted great attention for constructing flexible electronic devices due to its excellent deformability and electrical conductivity. However, its large surface tension makes it difficult to be uniformly dispersed in polymers, which severely limits its wide applications. Hence, a surfactant-free approach is proposed to prepare stable LM microspheres against precipitation and coalesce by facile ultrasonication via cellulose nanocrystal (CNC) stabilized LM-in-water Pickering emulsion (PE), where CNCs are employed as Pickering emulsifiers due their partial wettability with both LM and water phases, strong electrostatic adsorption and hydrogen bonding interactions with LM. So far, reports about LM PE and CNC-stabilized inorganic material PE are still rare. CNC/LM PE is employed as direct-writing inks on various substrates for delicate patterns. The pristine CNC/LM patterns show excellent photothermal conversion due to localized surface plasma resonance effect of CNC/LM microspheres. After activation by friction sintering, the LM patterns are highly electric conductive (1666.7 S m-1) due to the formation of LM connection. The activated LM patterns also displayed excellent Joule heating (83.2 °C at 0.9 V) and electromagnetic interference (EMI) shielding ability (585.7 dB mm-1) in X-band range.

Revolutionizing Inorganic Nanofibers: Bridging Functional Elements to a Future System

The advancement of intelligent ecosystems depends upon not only technological innovation but also a multidimensional understanding of material-world interactions. This theoretical transformation prompts increasing demands for multifunctional materials exhibiting hierarchical organization across multiple length scales. Inorganic nanofibers demonstrate potential in bridging the gap between microscale and macroscale through their three-dimensional architectures. However, their inherent brittleness, primarily resulting from inferior structural integrity poses, significantly limits their current applications. This critical limitation highlights the urgent necessity for developing fabrication strategies that simultaneously enhance the mechanical flexibility and robustness, ensuring reliable performance under extreme operational conditions. This comprehensive review systematically examines brittle mechanism fracture through multiscale analysis including molecular, nanoscale, and microscale dimensions. It presents innovative methodologies integrating simulation-guided structural design with advanced in situ characterization techniques capable of real-time monitoring under a practical stress-strain process. Furthermore, the discussion progresses to address contemporary challenges and emergent solutions in oxide nanofiber engineering, providing strategic insights for developing mechanically robust flexible systems with stable functional properties. Ultimately, this review examines the potential of inorganic nanofibers to overcome the limitations of nano powder materials and achieve their promising real-world applications.

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.

Design Strategies and Emerging Applications of Conductive Hydrogels in Wearable Sensing

Conductive hydrogels, integrating high conductivity, mechanical flexibility, and biocompatibility, have emerged as crucial materials driving the evolution of next-generation wearable sensors. Their unique ability to establish seamless interfaces with biological tissues enables real-time acquisition of physiological signals, external stimuli, and even therapeutic feedback, paving the way for intelligent health monitoring and personalized medical interventions. To fully harness their potential, significant efforts have been dedicated to tailoring the conductive networks, mechanical properties, and environmental stability of these hydrogels through rational design and systematic optimization. This review comprehensively summarizes the design strategies of conductive hydrogels, categorized into metal-based, carbon-based, conductive polymer-based, ionic, and hybrid conductive systems. For each type, the review highlights structural design principles, strategies for conductivity enhancement, and approaches to simultaneously enhance mechanical robustness and long-term stability under complex environments. Furthermore, the emerging applications of conductive hydrogels in wearable sensing systems are thoroughly discussed, covering physiological signal monitoring, mechano-responsive sensing platforms, and emerging closed-loop diagnostic-therapeutic systems. Finally, this review identifies key challenges and offers future perspectives to guide the development of multifunctional, intelligent, and scalable conductive hydrogel sensors, accelerating their translation into advanced flexible electronics and smart healthcare technologies.

Electrochemical pH Sensor Incorporated Wearables for State-of-the-Art Wound Care

Nonhealing chronic wounds pose severe physiological and psychological distress to patients, making them a significant concern for global public health. Effective wound management strategies assisted by smart wearable pH monitoring have the potential to substantially alleviate both social and economic burdens. The pH of the wound exudate serves as a valuable indicator for predicting infections and assessing the healing status of wounds. This review comprehensively summarizes fundamental aspects related to wound pH, with a particular emphasis on the relationships between pH and healing status, infections, and other biochemical parameters that are crucial for wound health. It systematically discusses advancements in electrochemical pH sensors specifically designed for wearable devices, emphasizing their core performance in the care of chronic wounds. Additionally, the review outlines the challenges faced by this field and suggests future directions for research and development.

Permeable Dual-Mode Pressure-Temperature Sensing Textile with Sweat Adsorption and Evaporation Capability

Permeable electronics are promising in improving the wearing comfort but still fail in dealing with the sweating issue. Herein, we develop a flexible and breathable dual-mode pressure-temperature sensor with sweat adsorption and evaporation capability. The device is constructed on a bilayer thermoplastic polyurethane (TPU)/polyacrylonitrile (PAN) nanofiber mat through electrospinning, where the PAN nanofibers are hydrophilic for sweat adsorption, while the TPU nanofibers are hydrophobic to block sweat invasion into the sensing structure. The diffused sweat evaporates into moisture, which then passes through the internal fabric microchannels across the whole substrate, ensuring excellent permeability. Besides, the pressure sensing based on a planar intronic supercapacitor and the temperature sensing based on a serpentine resistor work with no crosstalk between the two. Practical applications of the developed sensing textile for continuous monitoring of wrist pulse beating and skin temperature with unique sweat absorption and evaporation capability for dry skin status are well demonstrated. This work will boost the development of next-generation permeable electronics for wearable healthcare management with extreme comfort.

Connecting the Dots: Sintering of Liquid Metal Particles for Soft and Stretchable Conductors

This review focuses on the sintering of liquid metal particles (LMPs). Here, sintering means the partial merging or connecting of particles (or droplets) to form a network of percolated and, thus, conductive electrical pathways. LMPs are attractive materials because they can be suspended in a carrier fluid to create printable inks or distributed in an elastomer to create soft, stretchable composites. However, films and traces of LMPs are not typically conductive as fabricated due to the native oxide that forms on the surface of the particles. In the case of composites, polymers can also get between particles, making sintering more challenging. Sintering can be done via a variety of ways, such as mechanical, thermal, and chemical processing. This review discusses the mechanisms to sinter these particles, patterning techniques that use sintering, unique properties of sintered LMPs, and their practical applications in fields such as stretchable electronics, soft robotics, and active materials.

Wearable Mechanoluminescent Triboelectric Sensors for Real-Time Monitoring of Nighttime Sports Activities

Smart clothing that integrates active luminescence and motion monitoring holds significant importance for enhancing safety during nighttime activities. In this study, by combining mechanoluminescent materials (ZnS/Cu) with triboelectric nanogenerators, an intelligent yoga pant that actively emits light and senses joint movements during physical activities has been fabricated. The incorporation of silver fiber electrodes ensures breathability throughout the mechanoluminescent triboelectric sensor (MTS), contributing to the high comfort of wearable smart clothing. The doping of ZnS/Cu with organic silicone rubber enhances the dielectric constant of the triboelectric layer, thereby effectively enhancing the output signal of the MTS. Moreover, the mechanoluminescent materials convert the tension applied during joint flexion into dynamically varying light, alerting passing vehicles and safeguarding users during nighttime activities. An in-depth investigation was conducted on the relationship between the content of luminescent materials and the device's light intensity and output voltage under the same stretching conditions. The integration of a wearable signal acquisition system ensures real-time output of the electrical signals from the MTS during running, enabling online real-time monitoring of motion indicators such as joint bending angles and step counts. These findings provide feasible insights for the development of breathable, active luminescent smart clothing.

A Soft Patch for Dynamic Myocardial Infarction Monitoring

Wearable electronics for cardiac monitoring have been widely developed in the field of routine vital sign monitoring and arrhythmia determination due to their convenience and continuity. However, there are very few reports on the demonstration of a stretchable multilead electrocardiogram (ECG) patch integrated with myocardial infarction (MI) location capability. Here, we first propose a wearable dynamic cardiac monitoring patch, which can acquire seven-lead ECG signals continuously. A novel stretchable bioelectrode is mounted on the patch, which is strain-insensitive in the 100% tensile strain range. Moreover, the bioelectrode maintains good adhesion to the skin at more than 0.4 N/cm. This soft and wireless multilead ECG patch is designed for long-term, all-round real-time cardiac monitoring. For MI classification, a machine learning model for MI identification and location is trained with accuracy (99.93%) and sensitivity (99.98%). In addition, we also propose a new framework for the automated annotation of MI abnormal segments, which simultaneously addresses the recognition of abnormal waveforms and the integration of interlead relationships. This study contributes to the realization of personalized medical monitoring and intervention as well as early warning for MI.

Metal-Like Conductivity in Acid-Treated PEDOT:PSS Films: Surpassing 15,000 S/Cm

Although poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) films with high conductivity have been obtained through conventional organic solvent and acid treatment, their conductivity has not yet exceeded 10000 S/cm. In this paper, by combining blade-coating and treating with high concentration and volatilizable trifluoromethanesulfonic acid (CF3SO3H), PEDOT:PSS films with ultrahigh conductivity of 15143 S/cm, comparable to some metals, were prepared. Characterizations of morphology and structure indicate the formation of a perfectly continuous fibrous network structure, highly oriented crystallization, and tightly packed π-π stacking of PEDOT chains after removing a vast amount of PSS, which contributes to boosting the electrical conductivity of the treated PEDOT:PSS film. The distinguished electrical properties and ultrahigh conductivity enable it to replace metal materials as electrodes for "all-polymer" capacitive piezoelectric sensors with outstanding pressure sensitivity. Moreover, by regulating the blade-coating condition, the CF3SO3H-treated PEDOT:PSS films exhibit excellent electrochemical performance, which is an ideal channel material in organic electrochemical transistors (OECTs). The CF3SO3H-treated PEDOT:PSS film-based OECT devices display a high transconductance of 50.6 ± 5.5 mS and carrier mobility of 9.3 ± 1.5 cm2V-1s-1. This study not only provides new insights into the development of a simple and efficient PEDOT:PSS film treatment method but also expands its application in flexible electronics. Especially, the present research offers a useful reference in preparing "all-polymer"-based flexible electronic devices.

Stretchable and adhesive bilayers for electrical interfacing

Integrated stretchable devices, containing soft modules, rigid modules, and encapsulation modules, are of potential use in implantable bioelectronics and wearable devices. However, such systems often suffer from electrical deterioration due to debonding failure at the connection between rigid and soft modules induced by severe stress concentration, limiting their practical implementation. Here, we report a highly conductive and adhesive bilayer interface that can reliably connect soft-soft modules and soft-rigid modules together by simply pressing without conductive pastes. This interface configuration features a nanoscale styrene-ethylene-butylene-styrene (SEBS) elastomer layer and a SEBS-liquid metal (LM) composite layer. The top SEBS layer enables a strong adhesion with different modules. The connections between soft-soft and soft-rigid modules can be stretched to high strains of 400% and 250%, respectively. Coupling electron tunneling through an ultrathin SEBS layer with LM particle networks in a SEBS-LM composite layer renders continuous pathways for electrical conductivity. Such a bilayer interface exhibits a strain-insensitive high conductivity (3.7 × 105 S m-1) over a wide strain range from 0 to 680%, which can be facilely fabricated in a self-organized manner by sedimentation of LM particles. We present a proof-of-concept demonstration of this bilayer interface as an electrode, interconnect, and self-solder for monitoring physiological signals.

One-step fabrication of ultrathin porous Janus membrane within seconds for waterproof and breathable electronic skin

It remains a challenge for a simple and scalable method to fabricate ultrathin porous Janus membranes for stretchable on-skin electronics. Here, we propose a one-step droplet spreading phase separation strategy to prepare an ultrathin and easily collected Janus thermoplastic polyurethane (TPU) membrane within seconds. The metal-ion solvation structure mitigated migration kinetics to delay TPU solution demixing, promoting the further penetration of the coagulating solvent. Consequently, the developed membranes, with an average preparation rate of 25.2 cm2 s-1, had a thickness of 5 μm, and the water vapor transmission rate was determined to be 663 g m-2 d-1. The small pore layer having an average pore size of 1.7 μm effectively blocked external liquid water. The porous Janus TPU membrane coated by liquid metal served as a building block to develop a new generation of monolithic stretchable electronics with simultaneous high permeability and waterproofness.

Antifreezing Ultrathin Bioionic Gel-Based Wearable System for Artificial Intelligence-Assisted Arrhythmia Diagnosis in Hypothermia

Cardiovascular disease (CAD) is a major global public health issue, with mortality rates being significantly impacted by cold temperatures. Stable and reliable electrocardiogram (ECG) monitoring in cold environments is crucial for early detection and treatment of CAD. However, existing skin sensor struggle to balance freeze resistance, breathability, flexibility, conductivity and adhesion at cold temperatures. Here, we introduce a solvent cross-linking strategy and an in situ transfer method to prepare ultrathin bioionic gels, featuring a freezing point below -80 °C and a thickness of only 12.6 μm. The strong and abundant interactions between the ionic liquid solvent and the zwitterionic polymer effectively suppress low-temperature crystallization, forming a toughened and highly adhesive network structure. This network enables the in situ formation of an ultrathin morphology, which can be seamlessly transferred onto various substrates. Furthermore, the solvent-cross-linked network maintains a large interpolymer chain spacing, facilitating rapid ion transport pathways. Even at subzero temperatures, the gel maintains its multifunctionality, demonstrating tissue-like softness (34.6 kPa), high ionic conductivity (10.06 mS cm-1), excellent stretchability (360%), high transparency, robust adhesive strength (175.3 kPa) and interfacial toughness (1146 J m-2). Integrated into a flexible wearable device, the ultrathin gel ensures excellent skin conformity, user comfort, and high signal-to-noise ECG signal acquisition. Leveraging an artificial neural network, the system analyzes bradycardia ECG signals and achieves 96.88% accuracy in arrhythmia detection under cold conditions. This bioionic gel-based system presents a promising solution for early CAD diagnosis and prediction in extreme environments.

A Wireless Operated Flexible Bioelectronic Microneedle Patch for Actively Controlled Transdermal Drug Delivery

Precise control over drug release rates is critical for enhancing therapeutic efficacy, reducing side effects, and maintaining stable drug levels. While microneedles (MNs) offer a promising approach for transdermal drug delivery, conventional passive-response systems often lack adaptability across diverse drugs and disease models, limiting their versatility. Here, this work presents a flexible bioelectronic microneedle patch (FBMP) that integrates flexible electronics for actively controlled transdermal delivery. The FBMP incorporates a flexible printed circuit board (FPCB), a eutectic gallium-indium (EGaIn) heating film, and dual-layer microneedles with a polyvinyl alcohol (PVA) core and polycaprolactone (PCL) shell. This configuration allows real-time adjustment of the thermal response rate via smartphone-controlled Bluetooth, achieving rapid drug release within 2 min or sustained release over 10 h. In various animal models, the FBMP demonstrate versatility in delivering multiple drug types, optimizing efficacy, and minimizing side effects for both acute and chronic conditions. Overall, this work introduces a flexible, universal electronic microneedle platform with significant potential to advance precision and personalized medicine by enabling customizable, actively controlled drug release.

Stretchable and Permeable Liquid Metal Micromeshes Featuring Strain-Insensitive Resistance Through In Situ Structural Transformations

Gallium-based liquid metals hold promises for applications in stretchable electronics and beyond. However, these materials often encounter notable resistance increases during stretching and have negligible permeability to gases and liquids. This study presents an in situ structural transformation mechanism to create stretchable and permeable liquid metal micromeshes with strain-insensitive resistance. These micromeshes are fabricated by spin-coating liquid metal onto microfiber textiles and subjecting them to several stretching cycles. Consequently, the micromeshes transform from a smooth finish to wrinkled textures due to the growth in their oxide nanoskins. The distinct microstructure alters the stretching-relaxing mode to folding-unfolding, thereby minimizing fluctuations in resistance. The practical significance of this development is demonstrated through the fabrication of wearable heaters and LED matrices using transformed liquid metal micromeshes. Moreover, when integrated into Janus textiles featuring unidirectional water transport, these micromesh conductors act as sensing electrodes capable of acquiring high-fidelity biopotentials, even during intense sweating. These advancements highlight the capability of ambient air as a powerful reactive environment for tailoring the properties of microscale liquid metals.

Holocellulose nanofibrils biomimetic entrapment of liquid metal enable ultrastrong, tough, and lower-voltage-driven paper device

Integrating liquid metal (LM) with wood fibers for flexible paper electronics is intriguing yet extremely challenging due to poor mechanical performance. Here, we disclose a hemicellulose trapping strategy to achieve exceptional ultrastrong and tough LM-based paper electronics. Holocellulose nanofibrils (HCNFs) with hemicellulose retention of approximately 20 % are found to effectively entrap nanoscale LM within the fibril network, analogous to spider silk capturing small water droplets. Phase separation of LM and coalescence of nanofibrils can be avoided during the fabrication process of sheet-like paper. The homogeneous distribution of nanoscale LM eliminates impairment and contributes to the dramatic enhancement of mechanical performance (tensile strength: 240 MPa; toughness: 16.5 MJ m-3). Further incorporating a small number of carbon nanotubes generates low-voltage-driven Joule heating performance with excellent heat generation capacity (200 °C at 4.0 V), surpassing LM-based elastomers, films, and textiles. Our study illuminates the remarkable potential of LM-based paper electronics and enables advanced flexible device applications.

Wearable blood pressure sensors for cardiovascular monitoring and machine learning algorithms for blood pressure estimation

With advances in materials science and medical technology, wearable sensors have become crucial tools for the early diagnosis and continuous monitoring of numerous cardiovascular diseases, including arrhythmias, hypertension and coronary artery disease. These devices employ various sensing mechanisms, such as mechanoelectric, optoelectronic, ultrasonic and electrophysiological methods, to measure vital biosignals, including pulse rate, blood pressure and changes in heart rhythm. In this Review, we provide a comprehensive overview of the current state of wearable cardiovascular sensors, focusing particularly on those that measure blood pressure. We explore biosignal sensing principles, discuss blood pressure estimation methods (including machine learning algorithms) and summarize the latest advances in cuffless wearable blood pressure sensors. Finally, we highlight the challenges of and offer insights into potential pathways for the practical application of cuffless wearable blood pressure sensors in the medical field from both technical and clinical perspectives.

Advanced Morphological and Material Engineering for High-Performance Interfacial Iontronic Pressure Sensors

High-performance flexible pressure sensors are crucial for applications such as wearable electronics, interactive systems, and healthcare technologies. Among these, iontronic pressure sensors have garnered particular attention due to their superior sensitivity, enabled by the giant capacitance variation of the electric double layer (EDL) at the ionic-electronic interface under deformation. Key advancements, such as incorporating microstructures into ionic layers and employing diverse materials, have significantly improved sensor properties like sensitivity, accuracy, stability, and response time. This review highlights advancements in flexible EDL pressure sensors, focusing on structural designs and material engineering. These strategies are tailored to optimize key metrics such as sensitivity, detection limit, linearity, stability, response speed, hysteresis, transparency, wearability, selectivity, and multifunctionality. Key fabrication techniques, including micropatterning and externally assisted methods, are reviewed, along with strategies for sensor comparison and guidelines for selecting appropriate sensors. Emerging applications in healthcare, environmental and aerodynamic sensing, human-machine interaction, robotics, and machine learning-assisted intelligent sensing are explored. Finally, this review discusses the challenges and future directions for advancing EDL-based pressure sensors.

Dynamic Liquid Metal-Microfiber Interlocking Enables Highly Conductive and Strain-insensitive Metastructured Fibers for Wearable Electronics

Stretchable fibers with high conductivity are vital components for smart textiles and wearable electronics. However, embedding solid conductive materials in polymers significantly reduces conductive pathways when stretched, causing a sharp drop in conductivity. Here, a stretchable metastructured fiber with dynamic liquid metal-microfiber interlocking interface is reported to realize highly conductive yet ultrastable conductance. The Cu-EGaIn mixture is partially embedded within the porous microfiber mat, thereby enabling its roll-up into a spiral-layered metastructured fiber with self-compensating conductive pathways. The metastructured fiber shows outstanding performance, including high conductivity of 1.5 × 106 S m-1, large stretchability up to 629%, and ultrastable conductance with only 16% relative resistance change at 100% strain, which far surpasses the theoretical value. Moreover, these fibers have served as versatile platforms for wearable temperature-visualizing electrothermal fiber heaters and fully stretchable smart sensing-display fabrics. This dynamic solid-liquid interfacial interlocking strategy is promising for stretchable electronics.

Permeable and Durable Liquid-Metal Fiber Mat as Implantable Physiological Electrodes with Long-Term Biocompatibility

Implantable physiological electrodes provide unprecedented opportunities for real-time and uninterrupted monitoring of biological signals. Most implantable electronics adopt thin-film substrates with low permeability that severely hampers tissue metabolism, impeding their long-term biocompatibility. Recent innovations have seen the advent of permeable electronics through the strategic modification of liquid metals (LMs) onto porous substrates. However, the durability of these electronics is limited by the inherent poor wettability of LMs, particularly within the intricate 3D skeleton of the porous substrate. Herein, the study reports a spatial wettability tuning strategy that solves the wettability issue of LMs within the porous substrates, enabling the LM physiological electrodes with high durability and long-term biocompatibility. The study demonstrates the use of the electrodes as implantable neural interface to realize in vivo acquisition of electrocardiograph and electrocorticogram signals with long-term biocompatibility and high signal-to-noise ratio. This work demonstrates a promising direction for rational design of durable implantable bioelectronics with long-term biocompatibility.

Synergistic color-changing and conductive photonic cellulose nanocrystal patches for sweat sensing with biodegradability and biocompatibility

Given the ongoing requirements for versatility, sustainability, and biocompatibility in wearable applications, cellulose nanocrystal (CNC) photonic materials emerge as excellent candidates for multi-responsive wearable devices due to their tunable structural color, strong electron-donating capacity, and renewable nature. Nonetheless, most CNC-derived materials struggle to incorporate color-changing and electrical sensing into one system since the self-assembly of CNCs is incompatible with conventional conductive mediums. Here we report the design of a conductive photonic patch through constructing a CNC/polyvinyl alcohol hydrogel modulated by phytic acid (PA). The introduction of PA significantly enhances the hydrogen bonding interaction, resulting in the composite film with impressive flexibility (1.4 MJ m-3) and progressive color changes from blue, green, yellow, to ultimately red upon sweat wetting. Interestingly, this system simultaneously demonstrates selective and sensitive electrical sensing functions, as well as satisfactory biocompatibility, biodegradability, and breathability. Importantly, a proof-of-concept demonstration of a skin-adhesive patch is presented, where the optical and electrical dual-signal sweat sensing allows for intuitive visual and multimode electric localization of sweat accumulation during physical exercises. This innovative interactive strategy for monitoring human metabolites could offer a fresh perspective into the design of wearable health-sensing devices, while greatly expanding the applications of CNC-based photonic materials in medicine-related fields.

Reusable gallium-based electrochemical sensor for efficient glucose detection

Among wearable sensing devices, electrochemical sensors are overwhelming in biochemical detection due to their simple design but high sensitivity. Most electrochemical sensors are disposable, which significantly impairs the service life. Here we present a reusable gallium (Ga)-based multilayer electrochemical glucose biosensor to extend noninvasive monitoring of glucose in the interstitial fluid. This multilayer sensor includes Ga as a conductive interconnector, poly(3,4-ethylenedioxythiophene) as an electrode layer to prevent oxidation and metal leakage, a nano-Pt layer to enhance the electrochemical properties, and a nano-Prussian blue layer for reducing the hydrogen peroxide reduction potential. The biosensor can be renewed without causing damage to its overall structure by automatically eliminating the modified nanocomposites via the electrolysis-induced bubbles. The biosensor showed high sensitivity (24.6 μA mM-1 cm-2), wide linear range (0.01-26 mM), excellent stability (i.e., pH, long-term use) and superior selectivity, that is comparable to those of the current electrochemical tools for glucose detection. More importantly, incorporated with the reverse iontophoresis, the Ga-based hybrid sensor was applied as a skin patch on rat for the in vivo noninvasive and continuous monitoring of interstitial fluid glucose. The results showed a good correlation with that measured by blood glucometer. As a whole, this Ga-based electrochemical biosensor should endow new functions like biochemical analysis in biofluids for Ga-based bioelectronic sensing devices, in which almost are physical sensors. We believe that the reusability of electrochemically controllable processes may further inspire the development of more integrated and long-term stable Ga-based biosensing devices.

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.

Novel Thermoplastic Polyurethanes Enable Biaxially Stretchable Conductor for Supercapacitors with High Areal Capacitance

Stretchable supercapacitors are essential components in wearable electronics due to their low heat generation and seamless integration capabilities. Thermoplastic polyurethane elastomers, recognized for their dynamic hydrogen-bonding structure, exhibit excellent stretchability, making them well-suited for these applications. This study introduces fluorine-based interactions in the hard segments of thermoplastic polyurethanes, resulting in polyurethanes with a low elastic modulus, high fracture strength, exceptional fatigue resistance, and self-healing properties. By utilizing these polyurethanes as binders and meshed fabric as scaffolds, we developed highly stretchable conductors. These conductors maintain low resistance (∼26 ohms) under biaxial stretching and exhibit a stable bidirectional conductivity after 1600 stretching cycles. The fabricated supercapacitor electrode, incorporating fabric current collectors, polyurethane, and MXene, achieves an ultrahigh areal specific capacitance of 7200 mF cm-2 and retains 100% capacity after 2300 cycles. This material design strategy offers significant potential in elastic materials, stretchable conductors, and high-performance energy storage for wearable electronics.

Liquid Metal-Enabled Epidermal Interfaces

Soft materials are crucial for epidermal interfaces in biomedical devices due to their capability to conform to the body compared to rigid inorganic materials. Gels, liquids, and polymers have been extensively explored, but they lack sufficient electrical and thermal conductivity required for many application settings. Gallium-based alloys are molten metals at room temperature with exceptional electrical and thermal conductivity. These liquid metals and their composites can be directly applied onto the skin as interface materials. In this Spotlight on Applications, we focus on the rapidly evolving field of liquid metal-enabled epidermal interfaces featuring unique physical properties beyond traditional gels and polymers. We delve into the role of liquid metal in electrical and thermal biointerfaces in various epidermal applications. Current challenges and future directions in this active area are also discussed.

Multifunctional strain-activated liquid-metal composite films with electromechanical decoupling for stretchable electromagnetic shielding

The increasing miniaturization and intelligence of flexible electronic devices pose a challenge to the facile and scalable fabrication of multifunctional stretchable electromagnetic interference (EMI) shielding films with strain-stable shielding effectiveness (SE). This paper presents a highly stretchable liquid metal/thermoplastic polyurethane (LM/TPU) composite film produced via a facile method of scraping and pre-stretching induced activation. The TPU matrix endows the activated LM/TPU (ALMT) film with excellent tensile properties (elongation at break >700%), and the stable and malleable three-dimensional conductive LM network enables the ALMT film to exhibit almost negligible resistance changes and strain-enhanced conductivity during stretching, resulting in excellent strain-insensitive far-field and near-field shielding capabilities. Moreover, the high EMI SE up to ∼60 dB in the tensile state (0-400%) and reduced thickness from ∼75 to ∼50 μm during stretching allow the SE/thickness values of the ALMT film to increase from ∼700 to ∼1200 dB mm-1, outperforming most of the reported LM/polymer composites. Furthermore, the stretchability of the ALMT film provides efficient Joule-heating performance even under substantial deformation, and it can also serve as a strain sensor for real-time monitoring of human motion. The strain-insensitive EMI shielding behavior as well as the outstanding Joule heating and sensing performance of the ALMT film renders it a promising candidate for next-generation flexible electronic devices.

Breathable and Stretchable Epidermal Electronics for Health Management: Recent Advances and Challenges

Advanced epidermal electronic devices, capable of real-time monitoring of physical, physiological, and biochemical signals and administering appropriate therapeutics, are revolutionizing personalized healthcare technology. However, conventional portable electronic devices are predominantly constructed from impermeable and rigid materials, which thus leads to the mechanical and biochemical disparities between the devices and human tissues, resulting in skin irritation, tissue damage, compromised signal-to-noise ratio (SNR), and limited operational lifespans. To address these limitations, a new generation of wearable on-skin electronics built on stretchable and porous substrates has emerged. These substrates offer significant advantages including breathability, conformability, biocompatibility, and mechanical robustness, thus providing solutions for the aforementioned challenges. However, given their diverse nature and varying application scenarios, the careful selection and engineering of suitable substrates is paramount when developing high-performance on-skin electronics tailored to specific applications. This comprehensive review begins with an overview of various stretchable porous substrates, specifically focusing on their fundamental design principles, fabrication processes, and practical applications. Subsequently, a concise comparison of various methods is offered to fabricate epidermal electronics by applying these porous substrates. Following these, the latest advancements and applications of these electronics are highlighted. Finally, the current challenges are summarized and potential future directions in this dynamic field are explored.

A Versatile Microporous Design toward Toughened yet Softened Self-Healing Materials

Realizing the full potential of self-healing materials in stretchable electronics necessitates not only low modulus to enable high adaptivity, but also high toughness to resist crack propagation. However, existing toughening strategies for soft self-healing materials have only modestly improves mechanical dissipation near the crack tip (ГD), and invariably compromise the material's inherent softness and autonomous healing capabilities. Here, a synthetic microporous architecture is demonstrated that unprecedently toughens and softens self-healing materials without impacting their intrinsic self-healing kinetics. This microporous structure spreads energy dissipation across the entire material through a bran-new dissipative mode of adaptable crack movement (ГA), which substantially increases the fracture toughness by 31.6 times, from 3.19 to 100.86 kJ m-2, and the fractocohesive length by 20.7 times, from 0.59 mm to 12.24 mm. This combination of unprecedented fracture toughness (100.86 kJ m-2) and centimeter-scale fractocohesive length (1.23 cm) surpasses all previous records for synthetic soft self-healing materials and even exceeds those of light alloys. Coupled with significantly enhanced softness (0.43 MPa) and nearly perfect autonomous self-healing efficiency (≈100%), this robust material is ideal for constructing durable kirigami electronics for wearable devices.

3D Printing-Induced Hierarchically Aligned Nanocomposites With Exceptional Multidirectional Strain Sensing Performance

High-performance sensors capable of detecting multidirectional strains are indispensable to understand the complex motions involved in flexible electronics. Conventional isotropic strain sensors can only measure uniaxial deformations or single stimuli, hindering their practical application fields. The answer to such challenge resides in the construction of engineered anisotropic sensing structures. Herein, a hierarchically aligned carbon nanofiber (CNF)/polydimethylsiloxane nanocomposite strain sensor is developed by one-step 3D printing. The precisely controlled printing path and shear flow bring about highly aligned nanocomposite filaments at macroscale and orientated CNF network within each filament at microscale. The periodically orientated nanocomposite filaments along with the inner aligned CNF network successfully control the strain distribution and the appearance of microcracks, giving rise to anisotropic structural response to external deformations. The synergetic effect of the multiscale structural design leads to distinguishable gauge factors of 164 and 0.5 for applied loadings along and transverse to the alignment direction, leading to an exceptional selectivity of 3.77. The real-world applications of the hierarchically aligned sensors in multiaxial movement detector and posture-correction device are further demonstrated. The above findings propose new ideas for manufacturing nanocomposites with engineered anisotropic structure and properties, verifying promising applications in emerging wearable electronics and soft robotics.

ZnO Nanoparticle Assisted Liquid Metal for Dendrite-Free Zn Metal Anodes

Dendrite growth and interfacial side reactions on Zn anode seriously affect the safety and service life of Zn ions batteries. Interface engineering is an effective way to solve these problems. Here, a liquid metal-ZnO composite coating with high ionic conductivity is creatively designed, which not only reduces the Zn2+ diffusion barrier but also increases the hydrogen evolution overpotential, thereby eliminating dendrite growth behavior and corrosion on the modified Zn anode. Moreover, its unique structure induces Zn deposition into the inner of coating, which can effectively avoid the volume expansion in the deposit layer of Zn anode. Therefore, it can cycle for 3 000 h at an ultra-small polarization of 28 mV at 1 mA cm-2, and the microbattery assembled in combination with the MnO2 cathode also maintains 2 000 cycles with high Coulomb efficiency, providing a general idea for the development of the next generation of rechargeable metal batteries.

Multifunctional Porous Soft Composites for Bimodal Wearable Cardiac Monitors

Wearable heart monitors are crucial for early diagnosis and treatment of heart diseases in non-clinical settings. However, their long-term applications require skin-interfaced materials that are ultrasoft, breathable, antibacterial, and possess robust, enduring on-skin adherence-features that remain elusive. Here, we have developed multifunctional porous soft composites that meet all these criteria for skin-interfaced bimodal cardiac monitoring. The composite consists of a bilayer structure featuring phase-separated porous elastomer and slot-die-coated biogel. The porous elastomer ensures ultrasoftness, breathability, ease of handling, and mechanical integrity, while the biogel enables long-term on-skin adherence. Additionally, we incorporated ε-polylysine in the biogel to offer antibacterial properties. Also, the conductive biogel embedded with silver nanowires was developed for use in electrocardiogram sensors to reduce contact impedance and ensure high-fidelity recordings. Furthermore, we assembled a bimodal wearable cardiac monitoring system that demonstrates high-fidelity recordings of both cardiac electrical (electrocardiogram) and mechanical (seismocardiogram) signals over a 14-day testing period.

A Metalgel with Liquid Metal Continuum Immobilized in Polymer Network

Gels are formed by fluids that expand throughout the whole volume of 3D polymer networks. To unlock unprecedented properties, exploring new fluids immobilized in polymer networks is crucial. Here, a new liquid metal-polymer gel material termed "metalgel" is introduced via fluid replacement strategy, featuring 92.40% vol liquid metal fluid as a continuum immobilized by interconnected nanoscale polymer network. The unique structure endows metalgel with high electrical conductivity (up to 3.18 × 106 S·m‒1), tissue-like softness (Young's modulus as low as 70 kPa), and low gas permeability (4.50 × 10‒22 m2·s‒1·Pa‒1). Besides, metalgel demonstrates electrical stability under extreme deformations, such as being run over by a 4.5-metric-tonne truck, and maintains its integrity in various environments for up to 180 days. The immobilization of high-volume-fraction liquid metal fluid is realized by electrostatic interactions is further revealed. Potential applications for metalgel are diverse and include soft electromagnetic shielding, hermetic sealing, and stimulating/sensing electrodes in implantable bioelectronics, underscoring its broad applicability.

Research Progress of Flexible Electronic Devices Based on Electrospun Nanofibers

Electrospun nanofibers have become an important component in fabricating flexible electronic devices because of their permeability, flexibility, stretchability, and conformability to three-dimensional curved surfaces. This review delves into the advancements in adaptable and flexible electronic devices using electrospun nanofibers as the substrates and explores their diverse and innovative applications. The primary development of key substrates for flexible devices is summarized. After briefly discussing the principle of electrospinning, process parameters that affect electrospinning, and two major electrospinning techniques (i.e., single-fluid electrospinning and multifluid electrospinning), the review shines a spotlight on the recent breakthroughs in multifunctional and stretchable electronic devices that are based on electrospun substrates. These advancements include flexible sensors, flexible energy harvesting and storage devices, flexible accessories for electronic devices, and flexible environmental monitoring devices. In particular, the review outlines the challenges and potential solutions of developing electrospun nanofibers for flexible electronic devices, including overcoming the incompatibility of multiple interfaces, developing 3D microstructure sensor arrays with gradient geometry for various imperceptible on-skin devices, etc. This review may provide a comprehensive understanding of the rational design of application-oriented flexible electronic devices based on electrospun nanofibers.

Flexible Strain Sensors with Ultra-High Sensitivity and Wide Range Enabled by Crack-Modulated Electrical Pathways

This study presents a breakthrough in flexible strain sensor technology with the development of an ultra-high sensitivity and wide-range sensor, addressing the critical challenge of reconciling sensitivity with measurement range. Inspired by the structure of bamboo slips, we introduce a novel approach that utilises liquid metal to modulate the electrical pathways within a cracked platinum fabric electrode. The resulting sensor demonstrates a gauge factor greater than 108 and a strain measurement capability exceeding 100%. The integration of patterned liquid metal enables customisable tuning of the sensor's response, while the porous fabric structure ensures superior comfort and air permeability for the wearer. Our design not only optimises the sensor's performance but also enhances the electrical stability that is essential for practical applications. Through systematic investigation, we reveal the intrinsic mechanisms governing the sensor's response, offering valuable insights for the design of wearable strain sensors. The sensor's exceptional performance across a spectrum of applications, from micro-strain to large-strain detection, highlights its potential for a wide range of real-world uses, demonstrating a significant advancement in the field of flexible electronics.

Sustainable Nanofibril Interfaces for Strain-Resilient and Multimodal Porous Bioelectronics

Porous soft bioelectronics have attracted significant attention due to their high breathability, long-term biocompatibility, and other unique features inaccessible in nonporous counterparts. However, fabricating high-quality multimodal bioelectronic components that operate stably under strain on porous substrates, along with integrating microfluidics for sweat management, remains challenging. In this study, cellulose nanofibrils (CNF) are explored, biomass-derived sustainable biomaterials, as nanofibril interfaces with unprecedented interfacial robustness to enable high-quality printing of strain-resilient bioelectronics on porous substrates by reducing surface roughness and creating mechanical heterogeneity. Also, CNF-based microfluidics can provide continuous sweat collection and refreshment, crucial for accurate biochemical sensing. Building upon these advancements, a multimodal porous wearable bioelectronic system is further developed capable of simultaneously detecting electrocardiograms and glucose and beta-hydroxybutyrate in sweat for monitoring energy metabolism and consumption. This work introduces novel strategies for fabricating high-quality, strain-resilient porous bioelectronics with customizable multimodalities to meet arising personalized healthcare needs.

The Liquid Metal Age: A Transition From Hg to Ga

This review offers an illuminating journey through the historical evolution and modern-day applications of liquid metals, presenting a comprehensive view of their significance in diverse fields. Tracing the trajectory from mercury applications to contemporary innovations, the paper explores their pivotal role in industry and research. The analysis spans electrical switches, mechanical applications, electrodes, chemical synthesis, energy storage, thermal transport, electronics, and biomedicine. Each section examines the intricacies of liquid metal integration, elucidating their contributions to technological advancements and societal progress. Moreover, the review critically appraises the challenges and prospects inherent in liquid metal applications, addressing issues of recycling, corrosion management, device stability, economic feasibility, translational hurdles, and market dynamics. By delving into these complexities, the paper advances scholarly understanding and offers actionable insights for researchers, engineers, and policymakers. It aims to catalyze innovation, foster interdisciplinary collaboration, and promote liquid metal-enabled solutions for societal needs. Through its comprehensive analysis and forward-looking perspective, this review serves as a guide for navigating the landscape of liquid metal applications, bridging historical legacies with contemporary challenges, and highlighting the transformative potential of liquid metals in shaping future technologies.

Ultrathin Self-Healing Nanofibrous Membrane with a Hierarchical Confined Structure for Biomimetic Epidermal Electrodes

Integrating self-healing capabilities into epidermal electrodes is crucial to improving their reliability and longevity. Self-healing nanofibrous materials are considered an ideal candidate for constructing ultrathin, long-lasting wearable epidermal electrodes due to their lightweight and high breathability. However, due to the strong interaction between fibers, self-healing nanofiber membranes cannot exist stably. Therefore, the development of self-healing and breathable nanofibrous epidermal electrodes still remains a major challenge. Here, a hierarchical confinement strategy that combines molecular and spatial confinement to overcome supramolecular hydrogen bonding between self-healing nanofibers is reported, and an ultrathin self-healing nanofibrous epidermal electrode with a neural net-like structure is developed. It can achieve real-time monitoring of electrophysiological signals through long-term conformal attachment to skin or plants and has no adverse effects on skin health or plant growth. Given the almost imperceptible nature of epidermal electrodes to users and plants, it lays the foundation for the development of biocompatible, self-healing, wearable, flexible electronics.

A fully integrated breathable haptic textile

Wearable haptics serve as an enhanced media to connect humans and VR/robots. The inevitable sweating issue in all wearables creates a bottleneck for wearable haptics, as the sweat/moisture accumulated in the skin/device interface can substantially affect feedback accuracy, comfortability, and create hygienic problems. Nowadays, wearable haptics typically gain performance at the cost of sacrificing the breathability, comfort, and biocompatibility. Here, we developed a fully integrated breathable haptic textile (FIBHT) to solve these trade-off issues, where the FIBHT exhibits high-level integration of 128 pixels over the palm, great stretchability of 400%, and superior permeability of over 657 g/m2/day (moisture) and 40 mm/s (air). It is a stand-alone haptic system totally composed of stretchable, breathable, and bioadhesive materials, which empowers it with precise, sweating/movement-insensitive and dynamic feedback, and makes FIBHT powerful for virtual touching in broad scenarios.

Review of Liquid Metal Fiber Based Biosensors and Bioelectronics

Liquid metal, as a novel material, has become ideal for the fabrication of flexible conductive fibers and has shown great potential in the field of biomedical sensing. This paper presents a comprehensive review of the unique properties of liquid metals such as gallium-based alloys, including their excellent electrical conductivity, mobility, and biocompatibility. These properties make liquid metals ideal for the fabrication of flexible and malleable biosensors. The article explores common preparation methods for liquid metal conductive fibers, such as internal liquid metal filling, surface printing with liquid metal, and liquid metal coating techniques, and their applications in health monitoring, neural interfaces, and wearable devices. By summarizing and analyzing the current research, this paper aims to reveal the current status and challenges of liquid metal conductive fibers in the field of biosensors and to look forward to their development in the future, which will provide valuable references and insights for researchers in the field of biomedical engineering.

Nanoscale Strategies for Enhancing the Performance of Adhesive Dry Electrodes for the Skin

High-quality electrophysiological monitoring requires electrodes to maintain a compliant and stable skin contact. This necessitates low impedance, good skin compliance, and strong adhesion to ensure continuous and stable contact under dynamic conditions. In this context, adhesive epidermal dry electrodes are advancing rapidly, which is promising for long-term applications in clinical diagnosis, wearable health monitoring, and human-machine interfaces. However, challenges persist, as conventional technologies usually fall short of meeting the high standards required for electrophysiological electrodes. This Perspective discusses four key aspects for high-performance epidermal electrodes from an adhesive perspective: initial adhesion, water resistance, dynamic stability, and removal simplicity. We review recent nanoscale strategies addressing these issues, providing a comprehensive guideline to enhance the application performance of epidermal dry electrodes. Additionally, we explore key nanoscale strategies and their associated functions, future technology roadmaps, and prospects for dry adhesive epidermal electrodes.

Advancements in Flexible Electronics Fabrication: Film Formation, Patterning, and Interface Optimization for Cutting-Edge Healthcare Monitoring Devices

Flexible electronics can seamlessly adhere to human skin or internal tissues, enabling the collection of physiological data and real-time vital sign monitoring in home settings, which give it the potential to revolutionize chronic disease management and mitigate mortality rates associated with sudden illnesses, thereby transforming current medical practices. However, the development of flexible electronic devices still faces several challenges, including issues pertaining to material selection, limited functionality, and performance instability. Among these challenges, the choice of appropriate materials, as well as their methods for film formation and patterning, lays the groundwork for versatile device development. Establishing stable interfaces, both internally within the device and in human-machine interactions, is essential for ensuring efficient, accurate, and long-term monitoring in health electronics. This review aims to provide an overview of critical fabrication steps and interface optimization strategies in the realm of flexible health electronics. Specifically, we discuss common thin film processing methods, patterning techniques for functional layers, interface challenges, and potential adjustment strategies. The objective is to synthesize recent advancements and serve as a reference for the development of innovative flexible health monitoring devices.

MXene-Fiber Composite Membranes for Permeable and Biocompatible Skin-Interfaced Iontronic Mechanosensing

Artificial ionic sensory systems, bridging the divide between biological systems and electronics, mimic human skin functions but face critical challenges with biocompatibility, comfort, signal stability, and simplifying packaging. Here, we present a simple and permeable skin-interfaced iontronic mechanosensing (SIIM) architecture that integrates human skin as natural ionic material and hierarchically porous MXene-fiber composite membranes as sensing electrodes. The SIIM system eliminates complex ionic material design and multilayer matrix, exhibiting ultrahigh pressure sensitivities (5.4 kPa-1, <75 Pa), a low detection limit (6 Pa), excellent output stability along with high permeability to minimize the impact of sweating on sensing. The noncytotoxic nature of SIIM electrodes ensures excellent biocompatibility (>97% cell coincubational viability), facilitating long-term wearability and high biosafety. Furthermore, the scalable SIIM configuration integrated with matrix smart gloves, effectively monitors human physical movements. This SIIM-based sensor with marked sensing capabilities, structural simplicity, and scalability, holds promising potential in diverse wearable applications.

A Highly Stable, Multifunctional Janus Dressing for Treating Infected Wounds

The limited and unstable absorption of excess exudate is a major challenge during the healing of infected wounds. In this study, a highly stable, multifunctional Janus dressing with unidirectional exudate transfer capacity is fabricated based on a single poly(lactide caprolactone) (PLCL). The success of this method relies on an acid hydrolysis reaction that transforms PLCL fibers from hydrophobic to hydrophilic in situ. The resulting interfacial affinity between the hydrophilic/phobic PLCL fibers endows the Janus structure with excellent unidirectional liquid transfer and high structural stability against repeated stretching, bending, and twisting. Various other functions, including wound status detection, antibacterial, antioxidant, and anti-inflammatory properties, are also integrated into the dressing by incorporating phenol red and epigallocatechin gallate. An in vivo methicillin-resistant Staphylococcus aureus-infected wound model confirms that the Janus dressing, with the capability to remove exudate from the infected site, not only facilitates epithelialization and collagen deposition, but also ensures low inflammation and high angiogenesis, thus reaching an ideal closure rate up to 98.4% on day 14. The simple structure, multiple functions, and easy fabrication of the dressing may offer a promising strategy for treating chronic wounds, rooted in the challenges of bacterial infection, excessive exudate, and persistent inflammation.