Biometric-Tuned E-Skin Sensor with Real Fingerprints Provides Insights on Tactile Perception: Rosa Parks Had Better Surface Vibrational Sensation than Richard Nixon.

The dense mechanoreceptors in human fingertips enable texture discrimination. Recent advances in flexible electronics have created tactile sensors that effectively replicate slowly adapting (SA) and rapidly adapting (RA) mechanoreceptors. However, the influence of dermatoglyphic structures on tactile signal transmission, such as the effect of fingerprint ridge filtering on friction-induced vibration frequencies, remains unexplored. A novel multi-layer flexible sensor with an artificially synthesized skin surface capable of replicating arbitrary fingerprints is developed. This sensor simultaneously detects pressure (SA response) and vibration (RA response), enabling texture recognition. Fingerprint ridge patterns from notable historical figures - Rosa Parks, Richard Nixon, Martin Luther King Jr., and Ronald Reagan - are fabricated on the sensor surface. Vibration frequency responses to assorted fabric textures are measured and compared between fingerprint replicas. Results demonstrate that fingerprint topography substantially impacts skin-surface vibrational transmission. Specifically, Parks' fingerprint structure conveyed higher frequencies more clearly than those of Nixon, King, or Reagan. This work suggests individual fingerprint ridge morphological variation influences tactile perception and can confer adaptive advantages for fine texture discrimination. The flexible bioinspired sensor provides new insights into human vibrotactile processing by modeling fingerprint-filtered mechanical signals at the finger-object interface.

Multi-functional adhesive hydrogel as bio-interface for wireless transient pacemaker.

Traditional temporary cardiac pacemakers (TCPs), which employ transcutaneous leads and external wired power systems are battery-dependent and generally non-absorbable with rigidity, thereby necessitating surgical retrieval after therapy and resulting in potentially severe complications. Wireless and bioresorbable transient pacemakers have, hence, emerged recently, though hitting a bottleneck of unfavorable tissue-device bonding interface subject to mismatched mechanical modulus, low adhesive strength, inferior electrical performances, and infection risks. Here, to address such crux, we develop a multifunctional interface hydrogel (MIH) with superior electrical performance to facilitate efficient electrical exchange, comparable mechanical strength to natural heart tissue, robust adhesion property to enable stable device-tissue fixation (tensile strength: ∼30 kPa, shear strength of ∼30 kPa, and peel-off strength: ∼85 kPa), and good bactericidal effect to suppress bacterial growth. Through delicate integration of this versatile MIH with a leadless, battery-free, wireless, and transient pacemaker, the entire system exhibits stable and conformal adhesion to the beating heart while enabling precise and constant electrical stimulation to modulate the cardiac rhythm. It is envisioned that this versatile MIH and the proposed integration framework will have immense potential in overcoming key limitations of traditional TCPs, and may inspire the design of novel bioelectronic-tissue interfaces for next-generation implantable medical devices.

Baroreceptor-Inspired Microneedle Skin Patch for Pressure-Controlled Drug Release.

Objective: We have developed a baroreceptor-inspired microneedle skin patch for pressure-controlled drug release. Impact Statement: This design is inspired by the skin baroreceptors, which are mechanosensitive elements of the peripheral nervous system. We adopt the finger touching to trigger the electric stimulation, ensuring a fast-response and user-friendly administration with potentially minimal off-target effects. Introduction: Chronic skin diseases bring about large, recurrent skin damage and often require convenient and timely transdermal treatment. Traditional methods lack spatiotemporal controllable dosage, leaving a risk of skin irritation or drug resistance issues. Methods: The patch consists of drug-containing microneedles and stretchable electrode array. The electrode array, integrated with the piezoconductive switch and flexible battery, provides a mild electric current only at the spot that is pressed. Drugs in microneedles will then flow along the current into the skin tissues. The stretchable feature also provides the mechanical robustness and electric stability of the device on large skin area. Results: This device delivers Cy3 dye in pig skin with spatiotemporally controlled dosage, showing ~8 times higher fluorescence intensity than the passive delivery. We also deliver insulin and observe the reduction of the blood glucose level in the mouse model upon pressing. Compared with passive delivery without pressing, the dosage of drugs released by the simulation is 2.83 times higher. Conclusion: This baroreceptor-inspired microneedle skin patch acts as a good example of the biomimicking microneedle device in the precise control of the drug release profile at the spatiotemporal resolution.

High-Detectivity All-Polymer Photodiode Empowers Smart Vitality Surveillance and Computational Imaging Rivaling Silicon Diodes.

Near-infrared (NIR) organic photodetectors (OPDs), particularly all-polymer-based ones, hold substantial commercial promise in the healthcare and imaging sectors. However, the process of optimizing their active layer composition to achieve highly competitive figures of merit lacks a clear direction and methodology. In this work, celebrity polymer acceptor PY-IT into a more NIR absorbing host system PBDB-T:PZF-V, to significantly enhance the photodetection competence, is introduced. The refined all-polymer ternary broadband photodetector demonstrates superior performance metrics, including experimentally measured noise current as low as 6 fA Hz-1/2, specific detectivity reaching 8 × 1012 Jones, linear dynamic range (LDR) of 145 dB, and swift response speed surpassing 200 kHz, striking a fair balance between sensitivity and response speed. Comprehensive morphological and photophysical characterizations elucidate the mechanisms behind the observed performance enhancements in this study, which include reduced trap density, enhanced charge transport, diminished charge recombination, and balanced electron/hole mobilities. Moreover, the practical deployment potential of the proof-of-concept device in self-powered mode is demonstrated through their application in a machine learning-based cuffless blood pressure (BP) estimation system and in high-resolution computational imaging across complex environments, where they are found to quantitatively rival commercial silicon diodes.

Recent Advances in Materials, Devices and Algorithms Toward Wearable Continuous Blood Pressure Monitoring.

Continuous blood pressure (BP) tracking provides valuable insights into the health condition and functionality of the heart, arteries, and overall circulatory system of humans. The rapid development in flexible and wearable electronics has significantly accelerated the advancement of wearable BP monitoring technologies. However, several persistent challenges, including limited sensing capabilities and stability of flexible sensors, poor interfacial stability between sensors and skin, and low accuracy in BP estimation, have hindered the progress in wearable BP monitoring. To address these challenges, comprehensive innovations in materials design, device development, system optimization, and modeling have been pursued to improve the overall performance of wearable BP monitoring systems. In this review, we highlight the latest advancements in flexible and wearable systems toward continuous noninvasive BP tracking with a primary focus on materials development, device design, system integration, and theoretical algorithms. Existing challenges, potential solutions, and further research directions are also discussed to provide theoretical and technical guidance for the development of future wearable systems in continuous ambulatory BP measurement with enhanced sensing capability, robustness, and long-term accuracy.

Intelligent wearable olfactory interface for latency-free mixed reality and fast olfactory enhancement.

Olfaction feedback systems could be utilized to stimulate human emotion, increase alertness, provide clinical therapy, and establish immersive virtual environments. Currently, the reported olfaction feedback technologies still face a host of formidable challenges, including human perceivable delay in odor manipulation, unwieldy dimensions, and limited number of odor supplies. Herein, we report a general strategy to solve these problems, which associates with a wearable, high-performance olfactory interface based on miniaturized odor generators (OGs) with advanced artificial intelligence (AI) algorithms. The OGs serve as the core technology of the intelligent olfactory interface, which exhibit milestone advances in millisecond-level response time, milliwatt-scale power consumption, and the miniaturized size. Empowered by robust AI algorithms, the olfactory interface shows its great potentials in latency-free mixed reality (MR) and fast olfaction enhancement, thereby establishing a bridge between electronics and users for broad applications ranging from entertainment, to education, to medical treatment, and to human machine interfaces.

Flash healing of laser-induced graphene.

The advancement of laser-induced graphene (LIG) technology has streamlined the fabrications of flexible graphene devices. However, the ultrafast kinetics triggered by laser irradiation generates intrinsic amorphous characteristics, leading to high resistivity and compromised performance in electronic devices. Healing graphene defects in specific patterns is technologically challenging by conventional methods. Herein, we report the rapid rectification of LIG's topological defects by flash Joule heating in milliseconds (referred to as F-LIG), whilst preserving its overall structure and porosity. The F-LIG exhibits a decreased ID/IG ratio from 0.84 - 0.33 and increased crystalline domain from Raman analysis, coupled with a 5-fold surge in conductivity. Pair distribution function and atomic-resolution imaging delineate a broader-range order of F-LIG with a shorter C-C bond of 1.425 Å. The improved crystallinity and conductivity of F-LIG with excellent flexibility enables its utilization in high-performance soft electronics and low-voltage disinfections. Notably, our F-LIG/polydimethylsiloxane strain sensor exhibits a gauge factor of 129.3 within 10% strain, which outperforms pristine LIG by 800%, showcasing significant potential for human-machine interfaces.

ViboPneumo: A Vibratory-Pneumatic Finger-Worn Haptic Device for Altering Perceived Texture Roughness in Mixed Reality.

Extensive research has been done in haptic feedback for texture simulation in virtual reality (VR). However, it is challenging to modify the perceived tactile texture of existing physical objects which usually serve as anchors for virtual objects in mixed reality (MR). In this paper, we present ViboPneumo, a finger-worn haptic device that uses vibratory-pneumatic feedback to modulate (i.e., increase and decrease) the perceived roughness of the material surface contacted by the user's fingerpad while supporting the perceived sensation of other haptic properties (e.g., temperature or stickiness) in MR. Our device includes a silicone-based pneumatic actuator that can lift the user's fingerpad on the physical surface to reduce the contact area for roughness decreasing, and an on-finger vibrator for roughness increasing. The results of our perceptual study showed that the participants could perceive changes in roughness, both increasing and decreasing, compared to the original material surface. We also observed the overlapping roughness ratings among certain haptic stimuli (i.e., vibrotactile and pneumatic) and the originally perceived roughness of some materials without any haptic feedback. This suggests the potential to alter the perceived texture of one type of material to another in terms of roughness (e.g., modifying the perceived texture of ceramics as glass). Lastly, a user study of MR experience showed that ViboPneumo could significantly improve the MR user experience, particularly for visual-haptic matching, compared to the condition of a bare finger. We also demonstrated a few application scenarios for ViboPneumo.

A three-dimensional liquid diode for soft, integrated permeable electronics.

Wearable electronics with great breathability enable a comfortable wearing experience and facilitate continuous biosignal monitoring over extended periods1-3. However, current research on permeable electronics is predominantly at the stage of electrode and substrate development, which is far behind practical applications with comprehensive integration with diverse electronic components (for example, circuitry, electronics, encapsulation)4-8. Achieving permeability and multifunctionality in a singular, integrated wearable electronic system remains a formidable challenge. Here we present a general strategy for integrated moisture-permeable wearable electronics based on three-dimensional liquid diode (3D LD) configurations. By constructing spatially heterogeneous wettability, the 3D LD unidirectionally self-pumps the sweat from the skin to the outlet at a maximum flow rate of 11.6 ml cm-2 min-1, 4,000 times greater than the physiological sweat rate during exercise, presenting exceptional skin-friendliness, user comfort and stable signal-reading behaviour even under sweating conditions. A detachable design incorporating a replaceable vapour/sweat-discharging substrate enables the reuse of soft circuitry/electronics, increasing its sustainability and cost-effectiveness. We demonstrated this fundamental technology in both advanced skin-integrated electronics and textile-integrated electronics, highlighting its potential for scalable, user-friendly wearable devices.

Artificial Vascular with Pressure-Responsive Property based on Deformable Microfluidic Channels.

In vitro blood vessel models are significant for disease modeling, drug assays, and therapeutic development. Microfluidic technologies allow to create physiologically relevant culture models reproducing the features of the in vivo vascular microenvironment. However, current microfluidic technologies are limited by impractical rectangular cross-sections and single or nonsynchronous compound mechanical stimuli. This study proposes a new strategy for creating round-shaped deformable soft microfluidic channels to serve as artificial in vitro vasculature for developing in vitro models with vascular physio-mechanical microenvironments. Endothelial cells seeded into vascular models are used to assess the effects of a remodeled in vivo mechanical environment. Furthermore, a 3D stenosis model is constructed to recapitulate the flow disturbances in atherosclerosis. Soft microchannels can also be integrated into traditional microfluidics to realize multifunctional composite systems. This technology provides new insights into applying microfluidic chips and a prospective approach for constructing in vitro blood vessel models.

AI-Enabled Soft Sensing Array for Simultaneous Detection of Muscle Deformation and Mechanomyography for Metaverse Somatosensory Interaction.

Motion recognition (MR)-based somatosensory interaction technology, which interprets user movements as input instructions, presents a natural approach for promoting human-computer interaction, a critical element for advancing metaverse applications. Herein, this work introduces a non-intrusive muscle-sensing wearable device, that in conjunction with machine learning, enables motion-control-based somatosensory interaction with metaverse avatars. To facilitate MR, the proposed device simultaneously detects muscle mechanical activities, including dynamic muscle shape changes and vibrational mechanomyogram signals, utilizing a flexible 16-channel pressure sensor array (weighing ≈0.38 g). Leveraging the rich information from multiple channels, a recognition accuracy of ≈96.06% is achieved by classifying ten lower-limb motions executed by ten human subjects. In addition, this work demonstrates the practical application of muscle-sensing-based somatosensory interaction, using the proposed wearable device, for enabling the real-time control of avatars in a virtual space. This study provides an alternative approach to traditional rigid inertial measurement units and electromyography-based methods for achieving accurate human motion capture, which can further broaden the applications of motion-interactive wearable devices for the coming metaverse age.

Battery-free, wireless, and electricity-driven soft swimmer for water quality and virus monitoring.

Miniaturized mobile electronic system is an effective candidate for in situ exploration of confined spaces. However, realizing such system still faces challenges in powering issue, untethered mobility, wireless data acquisition, sensing versatility, and integration in small scales. Here, we report a battery-free, wireless, and miniaturized soft electromagnetic swimmer (SES) electronic system that achieves multiple monitoring capability in confined water environments. Through radio frequency powering, the battery-free SES system demonstrates untethered motions in confined spaces with considerable moving speed under resonance. This system adopts soft electronic technologies to integrate thin multifunctional bio/chemical sensors and wireless data acquisition module, and performs real-time water quality and virus contamination detection with demonstrated promising limits of detection and high sensitivity. All sensing data are transmitted synchronously and displayed on a smartphone graphical user interface via near-field communication. Overall, this wireless smart system demonstrates broad potential for confined space exploration, ranging from pathogen detection to pollution investigation.

Recent Advances in Bioelectronics for Localized Drug Delivery.

The last decade has witnessed remarkable advancements in bioelectronics, ushering in a new era of wearable and implantable devices for drug delivery. By utilizing miniaturized system design and/or flexible materials, bioelectronics illustrates ideal integration with target organs and tissues, making them ideal platforms for localized drug delivery. Furthermore, the development of electrically assisted drug delivery systems has enhanced the efficiency and safety of therapeutic administration, particularly for the macromolecules that encounter additional challenges in penetrating biological barriers. In this review, a concise overview of recent progress in bioelectronic devices for in vivo localized drug delivery, with highlights on the latest trends in device design, working principles, and their corresponding functionalities, is provided. The reported systems based on their targeted delivery locations as wearable systems, ingestible systems, and implantable systems are categorized. Each category is introduced in detail by highlighting the special requirements for devices and the corresponding solutions. The remaining challenges in this field and future directions are also discussed.

Thermal and Moisture Managing E-Textiles Enabled by Janus Hierarchical Gradient Honeycombs.

Moisture and thermal comfort are critical for long-term wear. In recent years, there has been rapidly growing attention on the importance of the comfortability in wearable electronic textiles (e-textiles), particularly in fields such as health monitoring, sports training, medical diagnosis and treatment, where long-term comfort is crucial. Nonetheless, simultaneously regulating thermal and moisture comfort for the human body without compromising electronic performance remains a significant challenge to date. Herein, a thermal and moisture managing e-textile (TMME-textile) that integrates unidirectional water transport and daytime radiative cooling properties with highly sensitive sensing performance is developed. The TMME-textile is made by patterning sensing electrodes on rationally designed Janus hierarchical gradient honeycombs that offer wetting gradient and optical management. The TMME-textile can unidirectionally pump excessive sweat, providing a dry and comfortable microenvironment for users. Moreover, it possesses high solar reflectivity (98.3%) and mid-infrared emissivity (89.2%), which reduce skin temperature by ≈7.0 °C under a solar intensity of 1 kW m-2. The TMME-textile-based strain sensor displays high sensitivity (0.1749 kPa-1) and rapid response rate (170 ms), effectively enabling smooth long-term monitoring, especially during high-intensity outdoor sports where thermal and moisture stresses are prominent challenges to conventional e-textiles.

[Application of electronic skin in healthcare and virtual reality].

Electronic skin has shown great application potential in many fields such as healthcare monitoring and human-machine interaction due to their excellent sensing performance, mechanical properties and biocompatibility. This paper starts from the materials selection and structures design of electronic skin, and summarizes their different applications in the field of healthcare equipment, especially current development status of wearable sensors with different functions, as well as the application of electronic skin in virtual reality. The challenges of electronic skin in the field of wearable devices and healthcare, as well as our corresponding strategies, are discussed to provide a reference for further advancing the research of electronic skin.

Skin-Integrated Wireless Odor Message Delivery Electronics for the Deaf-blind.

Deaf-blindness limits daily human activities, especially interactive modes of audio and visual perception. Although the developed standards have been verified as alternative communication methods, they are uncommon to the nondisabled due to the complicated learning process and inefficiency in terms of communicating distance and throughput. Therefore, the development of communication techniques employing innate sensory abilities including olfaction related to the cerebral limbic system processing emotions, memories, and recognition has been suggested for reducing the training level and increasing communication efficiency. Here, a skin-integrated and wireless olfactory interface system exploiting arrays of miniaturized odor generators (OGs) based on melting/solidifying odorous wax to release smell is introduced for establishing an advanced communication system between deaf-blind and non-deaf-blind. By optimizing the structure design of the OGs, each OG device is as small as 0.24 cm3 (length × width × height of 11 mm × 10 mm × 2.2 mm), enabling integration of up to 8 OGs on the epidermis between nose and lip for direct and rapid olfactory drive with a weight of only 24.56 g. By generating single or mixed odors, different linked messages could be delivered to a user within a short period in a wireless and programmable way. By adopting the olfactory interface message delivery system, the recognition rates for the messages have been improved 1.5 times that of the touch-based method, while the response times were immensely decreased 4 times. Thus, the presented wearable olfactory interface system exhibits great potential as an alternative message delivery method for the deaf-blind.

Wireless, battery-free, multifunctional integrated bioelectronics for respiratory pathogens monitoring and severity evaluation.

The rapid diagnosis of respiratory virus infection through breath and blow remains challenging. Here we develop a wireless, battery-free, multifunctional pathogenic infection diagnosis system (PIDS) for diagnosing SARS-CoV-2 infection and symptom severity by blow and breath within 110 s and 350 s, respectively. The accuracies reach to 100% and 92% for evaluating the infection and symptom severity of 42 participants, respectively. PIDS realizes simultaneous gaseous sample collection, biomarker identification, abnormal physical signs recording and machine learning analysis. We transform PIDS into other miniaturized wearable or portable electronic platforms that may widen the diagnostic modes at home, outdoors and public places. Collectively, we demonstrate a general-purpose technology for rapidly diagnosing respiratory pathogenic infection by breath and blow, alleviating the technical bottleneck of saliva and nasopharyngeal secretions. PIDS may serve as a complementary diagnostic tool for other point-of-care techniques and guide the symptomatic treatment of viral infections.

Wearable and battery-free wound dressing system for wireless and early sepsis diagnosis.

Sepsis is a severe organ dysfunction typically caused by wound infection which leads to septic shock, organ failure or even death if no early diagnosis and property medical treatment were taken. Herein, we report a soft, wearable and battery-free wound dressing system (WDS) for wireless and real-time monitoring of wound condition and sepsis-related biomarker (procalcitonin [PCT]) in wound exudate for early sepsis detection. The battery-free WDS powered by near-field communication enables wireless data transmission, signal processing and power supply, which allows portable intelligent wound caring. The exudate collection associates with soft silicone based microfluidic technologies (exudate collection time within 15 s), that can filtrate contamination at the cell level and enable a superior filtration rate up to 95% with adopting microsphere structures. The battery-free WDS also includes state-of-the-art biosensors, which can accurate detect the pH value, wound temperature, and PCT level and thus for sepsis diagnosis. In vivo studies of SD rats prove the capability of the WDS for continuously monitoring wound condition and PCT concentration in the exudate. As a result, the reported fully integrated WDS provides a potential solution for further developing wearable, multifunctional and on-site disease diagnosis.

Muscle-inspired soft robots based on bilateral dielectric elastomer actuators.

Muscle groups perform their functions in the human body via bilateral muscle actuation, which brings bionic inspiration to artificial robot design. Building soft robotic systems with artificial muscles and multiple control dimensions could be an effective means to develop highly controllable soft robots. Here, we report a bilateral actuator with a bilateral deformation function similar to that of a muscle group that can be used for soft robots. To construct this bilateral actuator, a low-cost VHB 4910 dielectric elastomer was selected as the artificial muscle, and polymer films manufactured with specific shapes served as the actuator frame. By end-to-end connecting these bilateral actuators, a gear-shaped 3D soft robot with diverse motion capabilities could be developed, benefiting from adjustable actuation combinations. Lying on the ground with all feet on the ground, a crawling soft robot with dexterous movement along multiple directions was realized. Moreover, the directional steering was instantaneous and efficient. With two feet standing on the ground, it also acted as a rolling soft robot that can achieve bidirectional rolling motion and climbing motion on a 2° slope. Finally, inspired by the orbicularis oris muscle in the mouth, a mouthlike soft robot that could bite and grab objects 5.3 times of its body weight was demonstrated. The bidirectional function of a single actuator and the various combination modes among multiple actuators together allow the soft robots to exhibit diverse functionalities and flexibility, which provides a very valuable reference for the design of highly controllable soft robots.