A General Strategy for an Efficient Biointerface via Enhanced Capacitive Coupling

Reliable sensing of bioelectronic signals is highly dependent on the efficient charge transfer at the biointerface, and the incorporation of biointerface materials would enhance it. Nevertheless, systematic investigations on interfacial electrochemical dynamics remain lacking, and universal fabrication criteria for such biointerface materials are yet to be established. Here, we propose a general strategy to promote interfacial charge transfer via enhancing capacitive coupling. We demonstrate this strategy by the design and synthesis of a hydrogel biointerface (HBI) that provides robust adhesion (adhesive strength up to ∼40 kPa) as well as conformal (Young's modulus < 50 kPa) and compliant (stretchability over 400%) contact with diverse bioelectronics and tissues. Importantly, the HBI enhances the capacitance three-fold and reduces the interfacial impedance over a wide frequency range. Bioelectrodes with HBI are capable of intraoperative neuromonitoring of motor evoked potentials (MEPs) during spinal surgery (lasting approximately 3 h). These results verify the effectiveness of our proposed strategy, which leverages enhanced capacitive coupling to establish an efficient and stable charge transfer interface for practical applications.