Tactile function is essential for human life as it enables us to recognize texture and respond to external stimuli, including potential threats with sharp objects that may result in punctures or lacerations. Severe skin damage caused by severe burns, skin cancer, chemical accidents, and industrial accidents damage the structure of the skin tissue as well as the nerve system, resulting in permanent tactile sensory dysfunction, which significantly impacts an individual’s daily life. Here, we introduce a fully-implantable wireless powered tactile sensory system embedded artificial skin (WTSA), with stable operation, to restore permanently damaged tactile function and promote wound healing for regenerating severely damaged skin. The fabricated WTSA facilitates (i) replacement of severely damaged tactile sensory with broad biocompatibility, (ii) promoting of skin wound healing and regeneration through collagen and fibrin-based artificial skin (CFAS), and (iii) minimization of foreign body reaction via hydrogel coating on neural interface electrodes. Furthermore, the WTSA shows a stable operation as a sensory system as evidenced by the quantitative analysis of leg movement angle and electromyogram (EMG) signals in response to varying intensities of applied pressures.

Transcranial focused ultrasound is a promising non-invasive method for neuromodulation, particularly for neurodegenerative and psychiatric conditions. However, its use in wearable systems has been limited due to bulky devices and reliance on ultrasound gel, which dehydrates and lacks stable adhesion for long-term use. Here, we present a miniaturized wearable ultrasound device, comparable in size to standard electrophysiological electrodes, integrated with a bioadhesive hydrogel for stable, long-term somatosensory cortical stimulation. Our air-cavity Fresnel lens based self-focusing acoustic transducer was fabricated via a lithography-free microfabrication process, achieving 30.7 W/cm² (1.92 MPa) acoustic intensity and 10 mm focal depth. The hydrogel couplant exhibited less than 13% acoustic attenuation and maintained a stable adhesion force of 0.961 N/cm for 35 days. Using this system, we successfully suppressed somatosensory evoked potentials elicited by functional electrical stimulation over 28 days, demonstrating the device’s potential for long-term, wearable neuromodulation applications.

This paper proposes a novel flexible electrode array based on Poly(dimethylsiloxane). PDMS is widely used in biomedical applications but it has shortcomings such as high water absorption and generation of micro-cracks in metal patterns on PDMS. To overcome such shortcomings, we applied parylene-C as an intermediate layer between PDMS and metal on one hand, and also applied parylene-C to fill the porous PDMS surface in order to reduce water absorption into PDMS on the other hand. In addition, we adopted Pt as adhesion layer between Au and parylene-C deposited PDMS. To verify the suitability of Pt as an adhesion layer, we performed 10 × 10 grid adhesion tests and pull-off tests, and compared the adhesion strength of Pt with those of Ti and Cr that are commonly used as adhesion layers in MEMS processes. Lastly, to evaluate the electrical characteristics and water absorption property of the fabricated electrode, electrochemical impedance spectroscopy (EIS) was measured. We expect our electrodes provide high flexibility and low water absorption that is desired for long-term neural signal recording.

Wearable bioelectronic interfaces capable of simultaneous neural sensing and targeted deep brain modulation remain limited by the lack of non-invasive technologies with sufficient spatial precision and mechanical stability for continuous operation. Here we report NEUSLeeP, a flexible skin-attached bioadhesive patch integrating electrophysiological sensing with transcranial focused ultrasound neuromodulation. The system incorporates a tunable concentric-ring ultrasound array, conformal hydrogel electrophysiological electrodes, and compliant interconnects within a soft substrate optimized for stable overnight operation. This integrated architecture enables spatially selective modulation and concurrent electrophysiological monitoring of deep brain structures, specifically the subthalamic nucleus during natural sleep. In a 28-participant study, NEUSLeeP demonstrated robust monitoring of sleep performance with precise-targeted neuromodulation of STN resulting in an increase in REM duration by 4.6% and reducing REM latency by 24%. This work establishes an ultrasound bioelectronic platform for non-invasive, spatiotemporally precise modulation and monitoring of deep neural circuits for neuroscience and bioelectronic medicine. ClinicalTrials.gov identifier: NCT07190287

Functional hydrogels are increasingly used in neural interfaces. As hydrophilic polymer networks that combine tissue-like softness with tunable conductivity and adhesion, they relieve two fundamental limitations of rigid conventional electrodes within a single material: the mechanical mismatch that drives the chronic foreign body response, and the electrical mismatch that raises interfacial impedance. This review discusses functional hydrogels through their core interfacial properties of biocompatibility, adhesion, and interfacial impedance/conductivity, and highlights how these requirements differ between skin-mounted wearable and implantable devices. Their applications in neural recording, electrical and ultrasound neuromodulation, and external and robotic device control are then covered in detail. Finally, the key challenges and future opportunities are summarized, including gelation control, long-term in vivo stability, integration with robotic hardware, and clinical translation. As the field advances, functional hydrogels are poised to become a core platform for next-generation neural interfaces.