Elastin-Based Janus Hydrogel Tape with Adhesive, Stretchable, and Conductive Properties for Soft Bioelectronic Applications

Achieving robust adhesion and optimal conductivity simultaneously is highly important and challenging for soft bioelectronics. Although numerous adhesive hydrogels have been investigated, they are designed for double-sided adhesion and lack optimal sensing performance. Therefore, we developed a two-step casting strategy to fabricate Janus hydrogel tape (J-Tape) for soft bioelectronics. The J-Tape was composed of an adhesive poly(acrylic acid)-N-hydroxysuccinimide/elastin-methacrylate (PAAc-NHS/ElaMA) bottom layer and a nonadhesive poly(acrylic acid)/gelatin-methacrylate (PAAc/GelMA) top layer and exhibited multiple functions, such as sufficient bioadhesion, high stretchability, optimal sensitivity, and good biocompatibility. Benefiting from the NHS ester group, the bottom layer can rapidly and robustly adhere to biological tissues. In addition, the top layer was supplemented with PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)) to enhance its conductive performance. The application of this J-Tape for tissue adhesion and wound sealing in vitro was successfully demonstrated. When exploited as a strain sensor to monitor diverse physiological signals, the hydrogel showed excellent sensitivity and reliability. Furthermore, J-Tape was integrated with a machine learning algorithm and developed into a wireless wearable electronic sensing system that can recognize diverse gestures with up to 98.87% accuracy. Overall, this work may provide new insights for the design and fabrication of functional bioelectronics.