Search

[Display omitted] • The PPPNV hydrogel possesses outstanding mechanical properties. • VBIMBr endowed the PPPNV hydrogel with excellent anti-freezing and anti-drying ability. • The PPPNV hydrogel strain sensor accurately monitored human physiological signals and motions. • The VPTT of PPPNV hydrogels can be tailored by VBIMBr content. • The PPPNV hydrogel exhibits good thermal sensitivity as a temperature sensor. Conductive hydrogels have received much attention in the field of flexible wearable sensors due to their outstanding flexibility, conductivity, sensitivity and excellent compatibility. However, most conductive hydrogels mainly focus on strain sensors to detect human motion and lack other features such as temperature response. Herein, we prepared a strain and temperature dual responsive ionic conductive hydrogel (PPPNV) with an interpenetrating network structure by introducing a covalent crosslinked network of N -isopropylacrylamide (NIPAAm) and 1-vinyl-3-butylimidazolium bromide (VBIMBr) into the skeleton of the hydrogel composed of polyvinylalcohol (PVA) and polyvinylpyrrolidone (PVP). The PPPNV hydrogel exhibited excellent anti-freezing properties (−37.34 °C) and water retention with high stretchability (∼930 %) and excellent adhesion. As a wearable strain sensor, the PPPNV hydrogel has good responsiveness and stability to a wide range of deformations and exhibits high strain sensitivity (GF=2.6) as well as fast response time. It can detect large and subtle body movements with good signal stability. As wearable temperature sensors, PPPNV hydrogels can detect human physiological signals and respond to temperature changes, and the volumetric phase transition temperature (VPTT) can be easily controlled by adjusting the molar ratio of NIPAAm to VBIMBr. In addition, a bilayer temperature-sensitive hydrogel was prepared with the temperature responsive hydrogel by two-step synthesis, which shows great promising applications in temperature actuators. [ABSTRACT FROM AUTHOR]

A dual-responsive hydrogel drug reservoir responding to body temperature and electrical stimulation achieves high drug release efficiency at 37 °C and efficient transdermal delivery. The Zn battery-driven iontophoresis results in an effective treatment of atopic dermatitis with the release of dexamethasone. This work provides a non-invasive treatment modality for chronic epidermal diseases that require precise drug delivery. [Display omitted] • Polyelectrolyte hydrogel shows thermal-electrochemical dual-responsive drug release. • Wearable Zn battery-powered iontophoresis for transdermal delivery with enhanced efficacy. • Effective treatment of atopic dermatitis in mice is achieved. Atopic dermatitis is a chronic, inflammation skin disease that remains a major public health challenge. The current drug-loading hydrogel dressings offer numerous benefits with enhanced loading capacity and a moist-rich environment. However, their development is still limited by the accessibility of a suitable driven source outside the clinical environment for precise control over transdermal delivery kinetics. Here, we prepare a sulfonated poly(3,4-ethylenedioxythiophene) (PEDOT) polyelectrolyte hydrogel drug reservoir that responds to different stimuli-both endogenous cue (body temperature) and exogenous cue (electrical stimulation), for wearable on-demand transdermal delivery with enhanced efficacy. Functioned as both the drug reservoir and cathode in a Zn battery-powered iontophoresis patch, this dual-responsive hydrogel achieves high drug release efficiency (68.4 %) at 37 °C. Evaluation in hairless mouse skin demonstrates the efficacy of this technology by facilitating transdermal transport of 12.2 μg cm−2 dexamethasone phosphate when discharged with a 103 Ω external resistor for 3 h. The Zn battery-driven iontophoresis results in an effective treatment of atopic dermatitis, displaying reductions in epidermal thickness, mast cell infiltration inhibition, and a decrease in IgE levels. This work provides a new treatment modality for chronic epidermal diseases that require precise drug delivery in a non-invasive way. [ABSTRACT FROM AUTHOR]

A novel cellulose hydrogel (MWCNTs/CNWs/PAM/SA) was prepared using a simple double cross-linked network synthesis method. It have good mechanical adaptability, high conductivity sensitivity (GF = 5.65, 53 ms), and low hysteresis (<11%). Additionally, it exhibits a sensitive response to water molecules as well as temperature-stimulated shape memory behavior. Hydrogels are designed as flexible tactile sensors that can accurately recognize and monitor electrical signals from different gesture movements and temperature changes. It was also assembled as a friction nanogenerator (TENG) that continuously generates a stable open circuit voltage (28 V) for self-powered small electronic devices. This provides the opportunity for accurate detection and fast feedback for flexible tactile sensors, green energy harvesting and power applications for small self-powered sensors, and may be a general approach to synthetic materials suitable for the development of future flexible electronic devices. [Display omitted] • MWCNTs and CNWs were introduced into PAM/SA hydrogels, which significantly improved the conductivity of the hydrogels. • The CWCNTs/CNWs/PAM/SA hydrogel tactile sensors can accurately recognize various gestures and temperature signals. • Hydrogel can be assembled into TENG for self-powered LEDs. This provides a strategy for green sustainable energy harvesting. Conductive hydrogels have been widely applied in human–computer interaction, tactile sensing, and sustainable green energy harvesting. Herein, a double cross-linked network composite hydrogel (MWCNTs/CNWs/PAM/SA) by constructing dual enhancers acting together with PAM/SA was constructed. By systematically optimizing the compositions, the hydrogel displayed features advantages of good mechanical adaptability, high conductivity sensitivity (GF = 5.65, 53 ms), low hysteresis (<11 %), and shape memory of water molecules and temperature. The nanocellulose crystals (CNWs) were bent and entangled with the backbone of the polyacrylamide/ sodium alginate (PAM/SA) hydrogel network, which effectively transferred the external mechanical forces to the entire physical and chemical cross-linking domains. Multi-walled carbon nanotubes (MWCNTs) were filled into the cross-linking network of the hydrogel to enhance the conductivity of the hydrogel effectively. Notably, hydrogels are designed as flexible tactile sensors that can accurately recognize and monitor electrical signals from different gesture movements and temperature changes. It was also assembled as a friction nanogenerator (TENG) that continuously generates a stable open circuit voltage (28 V) for self-powered small electronic devices. This research provides a new prospect for designing nanocellulose and MWCNTs reinforced conductive hydrogels via a facile method. [ABSTRACT FROM AUTHOR]

In this study, an adhesive, stretchable and freeze-resistant conductive hydrogel was prepared using a glycerol-water binary solvent combined with charged polar end groups. With the full convolutional network (FCN) algorithm, the hydrogel sensor achieves 96.4 % accuracy in recognizing handwritten English letters, demonstrating potential applications in flexible electronics and handwriting recognition. [Display omitted] Wearable electronics based on conductive hydrogels (CHs) offer remarkable flexibility, conductivity, and versatility. However, the flexibility, adhesiveness, and conductivity of traditional CHs deteriorate when they freeze, thereby limiting their utility in challenging environments. In this work, we introduce a PHEA-NaSS/G hydrogel that can be conveniently fabricated into a freeze-resistant conductive hydrogel by weakening the hydrogen bonds between water molecules. This is achieved through the synergistic interaction between the charged polar end group (−SO 3 −) and the glycerol-water binary solvent system. The conductive hydrogel is simultaneously endowed with tunable mechanical properties and conductive pathways by the modulation caused by varying material compositions. Due to the uniform interconnectivity of the network structure resulting from strong intermolecular interactions and the enhancement effect of charged polar end-groups, the resulting hydrogel exhibits 174 kPa tensile strength, 2105 % tensile strain, and excellent sensing ability (GF = 2.86, response time: 121 ms), and the sensor is well suited for repeatable and stable monitoring of human motion. Additionally, using the Full Convolutional Network (FCN) algorithm, the sensor can be used to recognize English letter handwriting with an accuracy of 96.4 %. This hydrogel strain sensor provides a simple method for creating multi-functional electronic devices, with significant potential in the fields of multifunctional electronics such as soft robotics, health monitoring, and human-computer interaction. [ABSTRACT FROM AUTHOR]

Advanced conductive hydrogels demonstrate substantial potential for wearable devices. Nevertheless, the transformative advance in soft electronics raises harsh requirements on the hydrogel candidates, such as rapid and on‐site fabrication, mechanical flexibility, high sensitivity, and wide use temperature. Here, this problem is overcome by incorporating a dual catalytic system based on lignin‐modified MXene‐Fe3+ into commercial hydrogels. This system 1) can form a composite hydrogel in a time scale of min at ambient condition without the supply of external energy, 2) incorporates multiple enhanced strategies into polymer chains, and 3) constructs well‐organized hybrid conductive network. The fabricated hydrogel displays an improved and balanced overall performance, including high ductility (2139%), moderate electrical conductivity, and strong temperature tolerance (−70–50 °C). Combined with the great merits of above performance, the hydrogel‐based sensor with good sensing (maximum GF: 2.8), stable repeatability (200% for 200 cycles), and wide work window of 0%–947%, thereby disclosing promising application in physiological movements, such as motion recognition and breathing state detection. Sensationally, even in complex or harsh surroundings, the sensors also produce stable and reliable signal output. Together, the strategy provides a new mentality of designing hydrogel materials for booming and advanced wearable electronics. [ABSTRACT FROM AUTHOR]

High mechanical strength, toughness, and fatigue resistance are essential to improve the reliability of conductive hydrogels for self‐powered sensing. However, achieving mutually exclusive properties simultaneously remains challenging. Hence, a novel directed interlocking strategy based on topological network structure and mechanical training is proposed to construct tough hydrogels by optimizing the network structure and modulating the orientation of molecular chains. Combining Zn2+ crosslinked cellulose nanofibers (CNFs) and a polyacrylamide‐poly(vinyl alcohol) double‐network, the unique interlocked‐network structure exhibits an enhanced toughening effect due to hydrogen bonding and metal‐ligand interactions. The aligned nanocrystalline domains achieved by training further contribute to an increase in the toughness and fatigue thresholds. This innovative approach synergistically enhances the mechanical properties of the nano‐conductive hydrogel, achieving a maximum tensile strength of 4.98 MPa and a toughness of 48 MJ m−3. Notably, the CNFs template with anchored polyaniline, when oriented through mechanical training, forms a unique directional conductive pathway, which significantly enhances the power output performance. Besides, a motion recognition system based on a self‐powered sensing device is designed with the assistance of deep learning techniques to accurately identify human motion behaviors. This work showcases a potentially transformative flexible electronic material for self‐powered sensing systems and intelligent recognition systems. [ABSTRACT FROM AUTHOR]

Annealing is a heat treatment process for materials. In this study, a conductive hydrogel was synthesized by a one-pot method using three raw materials: polyvinyl alcohol(PVA), carboxylated carbon nanotubes(Multi-Walled Carbon Nanotubes-COOH, MWCNTs-COOH) and polyethyleneimine (PEI). Based on the traditional freeze-thaw method for the preparation of PVA-based hydrogels, the annealing treatment was further added here to enhance the mechanical properties and fatigue resistance of the hydrogels. The synthesized conductive hydrogels were annealed in oven at different temperatures for a certain time, and the optimized experimental conditions and results were: the mechanical properties of the conductive hydrogel were best improved under the condition of 100 ℃-20 min, with the ultimate stress of 30.8 MPa and toughness as high as 779.58 MJ/m3. A high-strength, fatigue-resistant conductive hydrogel was successfully prepared, and its mechanical properties far exceeded those of other conductive hydrogels. Through a series of tests such as X-ray powder diffraction (XRD) and scanning electron microscopy (SEM), it was found that annealing promotes the orderly arrangement of PVA chains and crystallization through high temperatures, so as to enhance the mechanical properties of hydrogels. As a relatively simple and inexpensive annealing post-treatment technique, it is expected to be more widely used in improving the mechanical properties of hydrogels. [ABSTRACT FROM AUTHOR]

Copyright of Acta Materiae Compositae Sinica is the property of Acta Materiea Compositae Sinica Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Conductive hydrogels have great application potential in flexible electronic devices. Nevertheless, it is a huge challenge to fabricate multifunctional conductive hydrogels simultaneously integrated with high conductivity, self-healing performance, adhesiveness and anti-freezing ability. Herein, multifunctional ionic conductive hydrogels composed of sodium carboxymethyl cellulose, polyacrylic acid and NaCl are designed via a facile one-pot polymerization method based on the tannic acid-ferric ions autocatalytic system. The multifunctional hydrogel shows high stretchability (1170%, 104 kPa), an elastic modulus of 0.088 MPa, a toughness of 0.680 MJ m−3 and adhesiveness (wood: 22.95 ± 2.59 kPa). Metal coordination and H-bonding endow the hydrogel with good self-healing (98.3% for strain recovery), and NaCl is responsible for high ionic conductivity (2.818 S m−1) and anti-freezing performance (conductivity of 1.738 S m−1 at − 25 °C). The multifunctional hydrogel is assembled into a flexible supercapacitor with a high specific capacitance of 144.94 F g−1, long-term stability (15,000 cycles) and low-temperature tolerance (− 27.5 °C). A flexible strain sensor based on the multifunctional hydrogel has a gauge factor of 6.77 (750–1050%) and is applied for monitoring human motions. The multifunctional hydrogel also can serve as a flexible bioelectrode to detect electromyographic and electrocardiographic signals, even working at low temperature (− 7 °C). [ABSTRACT FROM AUTHOR]

Wearable devices have revolutionized real-time health monitoring, yet challenges persist in enhancing their flexibility, weight, and accuracy. This paper presents the development of a wearable device employing a conductive polyacrylamide–lithium chloride–MXene (PLM) hydrogel sensor, an electronic circuit, and artificial intelligence (AI) for gait monitoring. The PLM sensor includes tribo-negative polydimethylsiloxane (PDMS) and tribo-positive polyurethane (PU) layers, exhibiting extraordinary stretchability (317% strain) and durability (1000 cycles) while consistently delivering stable electrical signals. The wearable device weighs just 23 g and is strategically affixed to a knee brace, harnessing mechanical energy generated during knee motion which is converted into electrical signals. These signals are digitized and then analyzed using a one-dimensional (1D) convolutional neural network (CNN), achieving an impressive accuracy of 100% for the classification of four distinct gait patterns: standing, walking, jogging, and running. The wearable device demonstrates the potential for lightweight and energy-efficient sensing combined with AI analysis for advanced biomechanical monitoring in sports and healthcare applications. [ABSTRACT FROM AUTHOR]

The progress in electronic devices has led to more electromagnetic pollution. The importance of green and stable electromagnetic shielding devices cannot be overstated. Here, a PVA hydrogel reinforced by MXene and aramid nanofibers (ANFs) is prepared through solution exchange, freeze–thaw cycles, and the process of salting out. The unidirectional porous wall structure, combined with a water-rich environment connecting the MXene-dominated conductive network, and the rich interfaces endow the hydrogel with excellent EMI SE in the X-band at extremely low filler concentrations (1.5 wt %), reaching up to 64.5 dB. We determine the effect of MXene and water on the electromagnetic shielding effect by adjusting the content of MXene and water. The EMI SE of the 3 mm hydrogel increases by 33.4 dB when the MXene concentration augments from 0 to 1.5 wt %. Similarly, when the water content of hydrogels augments from 0 to 95 wt %, their EMI SE augments from 7.86 to 52 dB. In addition, the hydrogel exhibits excellent pressure sensing performance, capable of detecting motion with response and recovery times of 210 and 110 ms, respectively, and an optimal sensitivity of 0.308 kPa–1. It can also encode and encrypt information based on different signals, presenting profound prospects for smart sensing and wearable devices. [ABSTRACT FROM AUTHOR]

Organisms possess remarkably adaptive ability to complex environments. For example, chameleons can alter their skin color to adapt to varying environments, which has inspired significant advances in bioinspired soft electronic skins (E‐skins), and their wide applications in wearable sensors, intelligent robots, and health monitoring. However, current bioinspired E‐skins face challenges in ultra‐stretchability, high sensitivity, and long‐term stability owing to the intrinsic limitations associated with their mismatched interface between soft matrix and hard conductive fillers, hindering their practical applications. Here, it is reported that bioinspired structural color electronic skins (SC E‐skins) that consist of liquid metal particles (LMPs), periodical ordered colloidal crystal arrays, and ultra‐stretchable hydrogel, imparting synergistic and durable electrical–optical sensing capabilities. Such SC E‐skins demonstrate outstanding performances including superior flexibility (elongation at break > 1100%), high sensitivity (gauge factor = 3.26), fast synergetic electric–optical response time (≈100 ms), outstanding durability (over 1500 cycles), and high accuracy (R2 > 99.5%). These bioinspired SC E‐skins with excellent capability of converting mechanical signals into synergetic electrical–optical outputs hold great promise for smart wearable devices, affording a new horizon in developing advanced health monitoring technologies. [ABSTRACT FROM AUTHOR]

Mechanically robust and ionically conductive hydrogels poly(acrylamide‐co‐2‐acrylamido‐2‐methylpropanesulfonate‐lithium)/TiO2/SiO2 (P(AM‐co‐AMPSLi)/TiO2/SiO2) with inorganic hybrid crosslinking are fabricated through dual in situ sol‐gel reaction of vinyltriethoxysilane (VTES) and tetrabutyl titanate (TBOT), and in situ radical copolymerization of acrylamide (AM), 2‐acrylamide‐2‐methylpropanesulfonate‐lithium (AMPSLi), and vinyl‐SiO2. Due to the introduction of the sulfonic acid groups and Li+ by the reaction of AMPS with Li2CO3, the conductivity of the ionic hydrogel can reach 0.19 S m−1. Vinyl‐SiO2 and nano‐TiO2 are used in this hybrid hydrogel as both multifunctional hybrid crosslinkers and fillers. The hybrid hydrogels demonstrate high tensile strength (0.11–0.33 MPa) and elongation at break (98–1867%), ultrahigh compression strength (0.28–1.36 MPa), certain fatigue resistance, self‐healing, and self‐adhesive properties, which are due to covalent bonds between TiO2 and SiO2, as well as P(AM‐co‐AMPSLi) chains and SiO2, and noncovalent bonds between TiO2 and P(AM‐co‐AMPSLi) chains, as well as the organic frameworks. Furthermore, the specific capacitance, energy density, and power density of the supercapacitors based on ionic hybrid hydrogel electrolytes are 2.88 F g−1, 0.09 Wh kg−1, and 3.07 kW kg−1 at a current density of 0.05 A g−1, respectively. Consequently, the ionic hybrid hydrogels show great promise as flexible energy storage devices. [ABSTRACT FROM AUTHOR]

Soft bioelectronics have emerged as a promising platform for personalized healthcare, offering improved compatibility with biological tissues. Among various soft materials, hydrogels stand out due to their unique tissue-like properties and multifunctionality. However, the development of hydrogel-based bioelectronics faces three major challenges: (1) achieving a wide range of mechanical properties, from kilopascals to gigapascals, to match diverse tissues from soft brain to stiff tendon; (2) balancing and decoupling various material properties, particularly mechanical and electrical characteristics, and (3) achieving effective implantation and integration with target organs. This review provides a comprehensive overview of recent advancements in hydrogel-based bioelectronics, focusing on strategies to address these challenges. We first explore approaches to tune the mechanical properties of hydrogels, matching them with a wide range of tissues from soft brain tissue to stiff tendons. We then discuss innovative methods to incorporate conductivity into hydrogels while maintaining their mechanical integrity, highlighting recent developments in conductive polymers that show potential in decoupling electrical and mechanical properties. To address the challenge of implantation, we examine emerging concepts in stimuli-responsive hydrogels capable of programmable deformation, enabling targeted attachment and conformability to specific organs. We also categorize and analyze applications of hydrogel-based systems in both wearable and implantable devices, compiling the latest progress in hydrogel bioelectronics at the application level. While significant advancements have been made, integrating multiple functionalities within a single hydrogel-based device remains a considerable challenge. Further research is necessary to develop truly multimodal bioelectronic systems that can seamlessly interface with the human body, ultimately translating these promising technologies into clinical practice. Highlights: Summarizes recent advances in hydrogel bioelectronics for personalized healthcare, focusing on mechanical, electrical, acoustic, and optogenetic coupling. Discusses the latest progress in conductive polymers, particularly PEDOT:PSS, and their potential in decoupling electrical and mechanical properties. Discusses the concept of stimuli-responsive hydrogels that enable programmable deformation for targeted attachment and conformability to specific organs. [ABSTRACT FROM AUTHOR]

Conductive hydrogels are promising active materials for wearable flexible electronics, yet it is still challenging to fabricate conductive hydrogels with good environmental stability and electrical properties. In this work, a conductive MXene/LiCl/poly(sulfobetaine methacrylate) hydrogel system was successfully prepared with an impressive conductivity of 12.2 S/m. Interestingly, the synergistic effect of MXene and a lithium bond can significantly accelerate the polymerization process, forming the conductive hydrogel within 1 min. In addition, adding LiCl to the hydrogel not only significantly increases its water retention ability, but also enhances its conductivity, both of which are important for practical applications. The flexible strain sensors based on the as-prepared hydrogel have demonstrated excellent monitoring ability for human joint motion, pulse, and electromyographic signals. More importantly, based on machine learning image recognition technology, the handwritten letter recognition system displayed a high accuracy rate of 93.5%. This work demonstrates the excellent comprehensive performance of MXene-based hydrogels in health monitoring and image recognition and shows potential applications in human–machine interfaces and artificial intelligence. [ABSTRACT FROM AUTHOR]

In this work, PTDF composite hydrogel based on SiO 2 @PDA, F-HNT and PVA/PAM/TA/TiC hydrogel is investigated to achieve stable superhydrophobicity, self-cleaning and anti-fouling, excellent stretchability, sensitive conductivity, and applied to motion signal detection. [Display omitted] • A composite hydrogel was fabricated. • SiO 2 @PDA acting as an interlayer adhesive. • The surface is superhydrophobic. • The output signal can still be stabilized. With the advent of the information age, there is a growing demand for wearable sensing devices. Conventional hydrogels are a class of materials that can hold a large amount of water, with a three-dimensional network of hydrophilic polymerization chains inside. In remote areas or harsh environments, there is an urgent demand for a flexible sensor that is environmentally stable, wearable, and has high mechanical properties. Due to the hydrophilicity of the traditional hydrogel surface, it is easy to adsorb dust or be contaminated by liquid, which limits its further application. As a result, the superhydrophobic hydrogel F-PTD was designed using SiO 2 @PDA, F-HNT and PT hydrogel. TGA, XPS, SEM, EDS, FT-IR was used to characterize the structure of F-PTD, respectively. Based on the study of mussels, the adhesion property of polydopamine was utilized as an adhesion agent between organic–inorganic interfaces while improving the roughness of the hydrogel surface. The fabricated F-PTD superhydrophobic conductive hydrogels have excellent stretchability (Tensile Strain > 500 %), stable hydrophobicity (CA > 150°), and sensitive electrical conductivity (GF = 3.49). The contact angle of F-PTD is greater than 150° for tensile strains in the range of 0–350 %, and it maintains superhydrophobic under corrosive solutions with pH = 1–14. This enables F-PTD to perform the sensing function of detecting human body signals under complex environmental conditions, which has great potential for application in the field of underwater rescue, wearable electronics and human–computer interfaces. [ABSTRACT FROM AUTHOR]

Chitosan hydrogel with excellent degradability and biocompatibility has become an important material for constructing flexible strain sensors. Flexible strain sensors based on chitosan conductive hydrogels have superb environmental adaptability and are widely used in biomedical fields such as health monitoring and implantable devices. The preparation method and conductive mechanism of chitosan-based conductive hydrogels were reviewed. The current status of chitosan-based conductive hydrogels in low temperature resistant， self-repairing， and self-adhesive functional flexible strain sensors was summarized. Finally， it is pointed out that the optimization of the preparation process， the application of new materials， and the use of artificial intelligence are the key research directions for the future of chitosan-based conductive hydrogels for flexible strain sensors， aiming to provide theoretical foundations and practical guidance for the further development of multifunctional applications of flexible strain sensors.

Abstract Peripheral neural interfaces facilitate bidirectional communication between the nervous system and external devices, enabling precise control for prosthetic limbs, sensory feedback systems, and therapeutic interventions in the field of Bioelectronic Medicine. Intraneural interfaces hold great promise since they ensure high selectivity in communicating only with the desired nerve fascicles. Despite significant advancements, challenges such as chronic immune response, signal degradation over time, and lack of long-term biocompatibility remain critical considerations in the development of such devices. Here we report on the development and benchtop characterization of a novel design of an intraneural interface based on carbon fiber bundles. Carbon fibers possess low impedance, enabling enhanced signal detection and stimulation efficacy compared to traditional metal electrodes. We provided a 3D-stabilizing structure for the carbon fiber bundles made of PEDOT:PSS hydrogel, to enhance the biocompatibility between the carbon fibers and the nervous tissue. We further coated the overall bundles with a thin layer of elastomeric material to provide electrical insulation. Taken together, our results demonstrated that our electrode possesses adequate structural and electrochemical properties to ensure proper stimulation and recording of peripheral nerve fibers and a biocompatible interface with the nervous tissue.

Integrating superior mechanical performance, anisotropic conductivity, and biocompatibility into conductive hydrogels as all‐in‐one human‐machine interaction device remains challenging. Herein, by mimicking the anisotropic structures of human muscles, a robust anisotropic conductive hydrogel is developed by initially aligning polyvinyl alcohol with polypyrrole decorated cellulose nanofibrils to form an anisotropically oriented polymer networks, followed by post‐crosslinking with tannic acid (TA). Introducing TA into hydrogel network permanently secures its hierarchically anisotropic structure through multiple hydrogen bonds, thus endowing the hydrogel with exceptional mechanical properties (tensile strength of 11.41 MPa, toughness of 12.44 MJ m−3), anisotropic adhesive property, and direction‐dependent conductivity. With these attributes, a hydrogel strain sensor with excellent multidirectional sensitivity is developed, enabling stable monitoring of multi‐degrees of freedom joint movements in the human body and facilitating the control of a multiaxial virtual robot manipulator. Moreover, the in vitro/vivo tests demonstrate exceptional biocompatibility and anti‐biofouling properties of the as‐prepared hydrogel sensor, maintaining stable electronic response signals for over 14 days after successful implantation into the Achilles tendon of mice. Overall, this study presents a promising approach for designing conductive hydrogels with superior mechanical properties and anisotropic functionality for emerging applications in both in vitro and in vivo human‐machine interface materials. [ABSTRACT FROM AUTHOR]