Self-Powered Stretchable Sensor Arrays Exhibiting Magnetoelasticity for Real-Time Human-Machine Interaction

Screen-Printing of Carbons/Conductive Polymer Composite Inks for Smart Glove with High-Performance Textile Sensors

Flexible strain sensor-based smart textiles have promising applications in wearable devices. However, most existing smart textiles suffer from complex fabrication processes and inadequate control over the patterning and uniform deposition of conductive materials, which significantly hinder their commercialization. Herein, we propose a ternary composite ink system (graphene nanoplatelets/carbon black/PEDOT:PSS , G-C-P ink) by utilizing the synergistic effect of three different conductive components. This system exhibits superior rheological properties, enabling uniform deposition of patterned sensors on textile substrates through high-resolution screen printing. The synergistic interplay of ternary conductive materials overcomes the limitations of single/dual materials and endows the strain sensors with ultrahigh sensitivity (gauge factor = 1628 at 155-200% strain), broad working range (0-200% strain), and robust durability (>5000 cycles). Furthermore, stretchable interconnects based on silver fractal dendrites were integrated to extend the sensor array. Both sensors and interconnects were directly screen-printed onto the textile, achieving seamless compatibility with industrial textile manufacturing processes. Integration with printed circuit boards enabled a smart textile glove, demonstrating promising applications in gesture recognition and object-grasping recognition. This work establishes a scalable manufacturing paradigm for high-performance smart textiles and provides new possibilities for the commercialization of smart wearable textile systems.

Logarithmic Helical Design for Reversed Magnetic Field in Magnetoelastic Soft Matters with Giant Current Outputs

Magnetoelastic soft materials are widely used in soft bioelectronics. However, mechanical deformation usually induces minimal changes in magnetic flux, limiting electrical outputs. To overcome this limitation, a two-step process is employed to enhance the variation in magnetic flux density under mechanical force. On one hand, the helical structural design enables the magnetic membrane to flip completely, reversing the magnetic field. On the other hand, the applied mechanical force induces strain within the magnetoelastic membrane, leading to variations in magnetic flux density. A complete 180° reversal of the magnetic field is achieved using a logarithmic helical structure, resulting in a 200% increase in magnetic flux variation and a peak current of 6.34 mA. Following structural optimization, the current density reached an impressive 7.17 mA cm-2. Using this rationally designed logarithmic helix model, a knee pad is developed for wearable energy harvesting from human body movement. The device can generate a current of up to 2.83 mA, providing sufficient power for various small electronics, including smartphones, LED lights, headlamps, and rechargeable batteries. This achievement represents a significant milestone in advancing high-performance wearable biomechanical energy harvesting.

Stretchable, Rechargeable, Multimodal Hybrid Electronics for Decoupled Sensing toward Emotion Detection

Despite the rapid development of stretchable electronic devices for various applications in biomedicine and healthcare, the coupling between multiple input signals remains an obstacle in multimodal sensing before use in practical environments. This work introduces a fully integrated stretchable, rechargeable, multimodal hybrid device that combines decoupled sensors with a flexible wireless powering and transmitting module for emotion recognition. Through optimized structural design and material selection, the sensors can provide continuous real-time decoupled monitoring of biaxial strain, temperature, humidity, heart rate, and SpO2 levels. With a stacked bilayer for both the sensors and the flexible circuit, the rechargeable system showcases a reduced device footprint and improved comfort. A neural network model is also demonstrated to allow for high-precision facial expression recognition. By transmitting the real-time measured data to mobile devices and the cloud, the system can allow healthcare professionals to evaluate psychological health and provide emotional support through telemedicine when needed.

A Neural Device Inspired by Neuronal Oscillatory Activity with Intrinsic Perception and Decision-Making

Bionic neural devices often feature complex structures with multiple interfaces, requiring extensive post-processing. In this paper, a neural device with intrinsic perception and decision-making (NDIPD), inspired by neuronal oscillatory activity is introduced. The device utilizes alternating signals generated by coupling the human body with the power-frequency electromagnetic field as both a signal source and energy source, mimicking neuronal oscillatory activity. The peaks and valleys of the alternating signal are differentially modulated to replicate the baseline shift process in neuronal oscillatory activity. By comparing the amplitude of the peaks and valleys in the NDIPD's electrical output signal, the device achieves intrinsic perception and decision-making regarding the location of mechanical stimulation. This is accomplished using a single interface, which reduces data transmission, simplifies functionality, and eliminates the need for an external power supply. The NDIPD demonstrates a low-pressure detection limit (<0.02 N), fast response time (<20 ms), and exceptional stability (>200 000 cycles). It shows great potential for applications such as game control, UAV navigation, and virtual vehicle driving. The innovative energy supply method and sensing mechanism are expected to open new avenues in the development of bionic neural devices.

Van der Waals Heterojunction Based Self-Powered Biomimetic Dual-Mode Sensor for Precise Object Identification

The design and fabrication of materials that can concurrently respond to light and gas within the dual-modal recognition domain present a significant challenge due to contradictory structural requirements. This innovative strategy introduces a type-I heterojunction, combining the properties of Sb2Te3 and WSe2 nanosheets, to overcome these obstacles. The heterojunction is prepared through a precise stacking approach to create a single-side barrier on the valence band and a near-zero offset on the conduction band. The resulting Sb2Te3/WSe2 heterojunction demonstrates unparalleled performance, showcasing the best integrated photoelectric and gas sensing performance in a single device to date. Based on the above features, the heterojunction successfully integrates visual and olfactory sensing performance, achieving the first biomimetic visual-olfactory dual-mode recognition in a single device. This simulation increased the accuracy of distinguishing electric and fuel-powered cars from ≈50% to ≈96%. This work introduces a novel approach to creating efficient, self-powered sensing materials, paving the way for next-generation biomimetic dual-model devices with broad applications in environmental protection, medical care, and other fields.

Programmable Robotic Shape Shifting and Color Morphing Dynamics Through Magneto-Mechano-Chromic Coupling

Recreating natural organisms' dynamic shape-morphing and adaptive color-changing capabilities in a compact structure poses significant challenges but unlocks unprecedented hybridized robotic-visual applications. Overcoming programmability and predictability obstacles is key to achieving real-time, responsive changes in appearance and functionality, enhancing robot-environment-user interactions in ways previously unattainable. Herein, a Soft Magneto-Mechano-Chromic (SoMMeC) structure comprising a magnetic actuating and a synthetic photonic film, mirroring the intricate color-tuning mechanism of chameleons is devised. A model combining numerical simulation and a strain-dependent color evolution map enables precise predictions and controllable shape-color alterations across various geometrical and magnetization profiles. The SoMMeC exhibits rapid (0.1s), broad (full-visible spectrum), tether-free (remote magnetic manipulation), and programmable (model-guided control) color transformations, surpassing traditional limitations with its real-time response, broad and omnidirectional coloration for enhanced visibility, and robustness against external disturbances. The SoMMeC translates into dynamic advertising iridescence, adaptive camouflage, self-sensing, and multi-level encryption, and transcends traditional robotics by seamlessly blending dynamic movement with nuanced visual changes. It opens up a spectrum of applications that redefine robotic functionality through dynamic appearance modulation, making robotic systems more versatile, adaptive, and suitable for unexplored integrative functions.

Bioinspired Passive Tactile Sensors Enabled by Reversible Polarization of Conjugated Polymers

Tactile perception plays a vital role for the human body and is also highly desired for smart prosthesis and advanced robots. Compared to active sensing devices, passive piezoelectric and triboelectric tactile sensors consume less power, but lack the capability to resolve static stimuli. Here, we address this issue by utilizing the unique polarization chemistry of conjugated polymers for the first time and propose a new type of bioinspired, passive, and bio-friendly tactile sensors for resolving both static and dynamic stimuli. Specifically, to emulate the polarization process of natural sensory cells, conjugated polymers (including poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate), polyaniline, or polypyrrole) are controllably polarized into two opposite states to create artificial potential differences. The controllable and reversible polarization process of the conjugated polymers is fully in situ characterized. Then, a micro-structured ionic electrolyte is employed to imitate the natural ion channels and to encode external touch stimulations into the variation in potential difference outputs. Compared with the currently existing tactile sensing devices, the developed tactile sensors feature distinct characteristics including fully organic composition, high sensitivity (up to 773 mV N-1), ultralow power consumption (nW), as well as superior bio-friendliness. As demonstrations, both single point tactile perception (surface texture perception and material property perception) and two-dimensional tactile recognitions (shape or profile perception) with high accuracy are successfully realized using self-defined machine learning algorithms. This tactile sensing concept innovation based on the polarization chemistry of conjugated polymers opens up a new path to create robotic tactile sensors and prosthetic electronic skins.

High-Performance Stretchable Strain Sensors Based on Auxetic Fabrics for Human Motion Detection

Wearable strain sensors play a pivotal role in real-time human motion detection and health monitoring. Traditional fabric-based strain sensors, typically with a positive Poisson's ratio, face challenges in maintaining sensitivity and comfort during human motion due to conflicting resistance changes in different strain directions. In this work, high-performance stretchable strain sensors are developed based on graphene-modified auxetic fabrics (GMAF) for human motion detection in smart wearable devices. The proposed GMAF sensors, with a negative Poisson's ratio achieved through commercially available warp-knitting technology, exhibit an 8-fold improvement in sensitivity compared to conventional plain fabric sensors. The unique auxetic fabric structure enhances sensitivity by synchronizing resistance changes in both wale and course directions. The GMAF sensors demonstrate excellent washability, showing only slight degradation in auxeticity and an acceptable increase in resistance after 10 standard wash cycles. The GMAF sensors maintain stability under different strain levels and various motion frequencies, emphasizing their dynamic performance. The sensors exhibit superior conformability to joint movements, which effectively monitor a full range of motions, including joint bending, sports activities, and subtle actions like coughing and swallowing. The research underscores a promising approach to achieve industrial-scale production of wearable sensors with improved performance and comfort through fabric structure design.

Zero-Biased Bionic Fingertip E-Skin with Multimodal Tactile Perception and Artificial Intelligence for Augmented Touch Awareness

Electronic skins (E-Skins) are crucial for future robotics and wearable devices to interact with and perceive the real world. Prior research faces challenges in achieving comprehensive tactile perception and versatile functionality while keeping system simplicity for lack of multimodal sensing capability in a single sensor. Two kinds of tactile sensors, transient voltage artificial neuron (TVAN) and sustained potential artificial neuron (SPAN), featuring self-generated zero-biased signals are developed to realize synergistic sensing of multimodal information (vibration, material, texture, pressure, and temperature) in a single device instead of complex sensor arrays. Simultaneously, machine learning with feature fusion is applied to fully decode their output information and compensate for the inevitable instability of applied force, speed, etc, in real applications. Integrating TVAN and SPAN, the formed E-Skin achieves holistic touch awareness in only a single unit. It can thoroughly perceive an object through a simple touch without strictly controlled testing conditions, realize the capability to discern surface roughness from 0.8 to 1600 µm, hardness from 6HA to 85HD, and correctly distinguish 16 objects with temperature variance from 0 to 80 °C. The E-skin also features a simple and scalable fabrication process, which can be integrated into various devices for broad applications.

Evolution of Musculoskeletal Electronics

The musculoskeletal system, constituting the largest human physiological system, plays a critical role in providing structural support to the body, facilitating intricate movements, and safeguarding internal organs. By virtue of advancements in revolutionized materials and devices, particularly in the realms of motion capture, health monitoring, and postoperative rehabilitation, "musculoskeletal electronics" has actually emerged as an infancy area, but has not yet been explicitly proposed. In this review, the concept of musculoskeletal electronics is elucidated, and the evolution history, representative progress, and key strategies of the involved materials and state-of-the-art devices are summarized. Therefore, the fundamentals of musculoskeletal electronics and key functionality categories are introduced. Subsequently, recent advances in musculoskeletal electronics are presented from the perspectives of "in vitro" to "in vivo" signal detection, interactive modulation, and therapeutic interventions for healing and recovery. Additionally, nine strategy avenues for the development of advanced musculoskeletal electronic materials and devices are proposed. Finally, concise summaries and perspectives are proposed to highlight the directions that deserve focused attention in this booming field.

Biocompatible Electronic Skins for Cardiovascular Health Monitoring

Cardiovascular diseases represent a significant threat to the overall well-being of the global population. Continuous monitoring of vital signs related to cardiovascular health is essential for improving daily health management. Currently, there has been remarkable proliferation of technology focused on collecting data related to cardiovascular diseases through daily electronic skin monitoring. However, concerns have arisen regarding potential skin irritation and inflammation due to the necessity for prolonged wear of wearable devices. To ensure comfortable and uninterrupted cardiovascular health monitoring, the concept of biocompatible electronic skin has gained substantial attention. In this review, biocompatible electronic skins for cardiovascular health monitoring are comprehensively summarized and discussed. The recent achievements of biocompatible electronic skin in cardiovascular health monitoring are introduced. Their working principles, fabrication processes, and performances in sensing technologies, materials, and integration systems are highlighted, and comparisons are made with other electronic skins used for cardiovascular monitoring. In addition, the significance of integrating sensing systems and the updating wireless communication for the development of the smart medical field is explored. Finally, the opportunities and challenges for wearable electronic skin are also examined.

Highly Flexible, High-Performance, and Stretchable Piezoelectric Sensor Based on a Hierarchical Droplet-Shaped Ceramics with Enhanced Damage Tolerance

Stretchable self-powered sensors are of significant interest in next-generation wearable electronics. However, current strategies for creating stretchable piezoelectric sensors based on piezoelectric polymers or 0-3 piezoelectric composites face several challenges such as low piezoelectric activity, low sensitivity, and poor durability. In this paper, a biomimetic soft-rigid hybrid strategy is used to construct a new form of highly flexible, high-performance, and stretchable piezoelectric sensor. Inspired by the hinged bivalve Cristaria plicata, hierarchical droplet-shaped ceramics are manufactured and used as rigid components, where computational models indicate that the unique arched curved surface and rounded corners of this bionic structure can alleviate stress concentrations. To ensure electrical connectivity of the piezoelectric phase during stretching, a patterned liquid metal acts as a soft circuit and a silicone polymer with optimized wettability and stretchability serves as a soft component that forms a strong mechanical interlock with the hierarchical ceramics. The novel sensor design exhibits excellent sensitivity and durability, where the open circuit voltage remains stable after 5000 stretching cycles at 60% strain and 5000 twisting cycles at 180°. To demonstrate its potential in heathcare applications, this new stretchable sensor is successfully used for wireless gesture recognition and assessing the progression of knee osteoarthritis.

Single Channel Based Interference-Free and Self-Powered Human-Machine Interactive Interface Using Eigenfrequency-Dominant Mechanism

The recent development of wearable devices is revolutionizing the way of human-machine interaction (HMI). Nowadays, an interactive interface that carries more embedded information is desired to fulfill the increasing demand in era of Internet of Things. However, present approach normally relies on sensor arrays for memory expansion, which inevitably brings the concern of wiring complexity, signal differentiation, power consumption, and miniaturization. Herein, a one-channel based self-powered HMI interface, which uses the eigenfrequency of magnetized micropillar (MMP) as identification mechanism, is reported. When manually vibrated, the inherent recovery of the MMP causes a damped oscillation that generates current signals because of Faraday's Law of induction. The time-to-frequency conversion explores the MMP-related eigenfrequency, which provides a specific solution to allocate diverse commands in an interference-free behavior even with one electric channel. A cylindrical cantilever model is built to regulate the MMP eigenfrequencies via precisely designing the dimensional parameters and material properties. It is shown that using one device and two electrodes, high-capacity HMI interface can be realized when the magnetic micropillars (MMPs) with different eigenfrequencies have been integrated. This study provides the reference value to design the future HMI system especially for situations that require a more intuitive and intelligent communication experience with high-memory demand.

Design of Double Conductive Layer and Grid-Assistant Face-to-Face Structure for Wide Linear Range, High Sensitivity Flexible Pressure Sensors

Recently, flexible pressure sensors have drawn great attention because of their potential application in human-machine interfaces, healthcare monitoring, electronic skin, etc. Although many sensors with good performance have been reported, researchers mostly focused on surface morphology regulation, and the effect of the resistance characteristics on the performance of the sensor was still rarely systematically investigated. In this paper, a strategy for modulating electron transport is proposed to adjust the linear range and sensitivity of the sensor. In the modulating process, we constructed a double conductive layer (DCL) and grid-assistant face-to-face structure and obtained the sensor with a wide linear range of 0-700 kPa and a high sensitivity of 57.5 kPa-1, which is one of the best results for piezoresistive sensors. In contrast, the sensor with a single conductive layer (SCL) and simple face-to-face structure exhibited a moderate linear range (7 kPa) and sensitivity (2.8 kPa-1). Benefiting from the great performance, the modulated sensor allows for clear pulse wave detection and good recognition of gait signals, which indicates the great application potential in human daily life.

A Review of Epidermal Flexible Pressure Sensing Arrays

In recent years, flexible pressure sensing arrays applied in medical monitoring, human-machine interaction, and the Internet of Things have received a lot of attention for their excellent performance. Epidermal sensing arrays can enable the sensing of physiological information, pressure, and other information such as haptics, providing new avenues for the development of wearable devices. This paper reviews the recent research progress on epidermal flexible pressure sensing arrays. Firstly, the fantastic performance materials currently used to prepare flexible pressure sensing arrays are outlined in terms of substrate layer, electrode layer, and sensitive layer. In addition, the general fabrication processes of the materials are summarized, including three-dimensional (3D) printing, screen printing, and laser engraving. Subsequently, the electrode layer structures and sensitive layer microstructures used to further improve the performance design of sensing arrays are discussed based on the limitations of the materials. Furthermore, we present recent advances in the application of fantastic-performance epidermal flexible pressure sensing arrays and their integration with back-end circuits. Finally, the potential challenges and development prospects of flexible pressure sensing arrays are discussed in a comprehensive manner.

Bioinspired Dual-Mode Stretchable Strain Sensor Based on Magnetic Nanocomposites for Strain/Magnetic Discrimination

Recently, flexible stretchable sensors have been gaining attention for their excellent adaptability for electronic skin applications. However, the preparation of stretchable strain sensors that achieve dual-mode sensing while still retaining ultra-low detection limit of strain, high sensitivity, and low cost is a pressing task. Herein, a high-performance dual-mode stretchable strain sensor (DMSSS) based on biomimetic scorpion foot slit microstructures and multi-walled carbon nanotubes (MWCNTs)/graphene (GR)/silicone rubber (SR)/Fe₃ O₄ nanocomposites is proposed, which can accurately sense strain and magnetic stimuli. The DMSSS exhibits a large strain detection range (≈160%), sensitivity up to 100.56 (130-160%), an ultra-low detection limit of strain (0.16% strain), and superior durability (9000 cycles of stretch/release). The sensor can accurately recognize sign language movement, as well as realize object proximity information perception and whole process information monitoring. Furthermore, human joint movements and micro-expressions can be monitored in real-time. Therefore, the DMSSS of this work opens up promising prospects for applications in sign language pose recognition, non-contact sensing, human-computer interaction, and electronic skin.