A Degradable and Biocompatible Supercapacitor Implant Based on Functional Sericin Hydrogel Electrode

Abstract Implantable power sources face great challenges in balancing multiple factors including high performance, biocompatibility, mechanical properties for soft tissue fit, and biodegradability. Toward this goal, a simple and feasible method is proposed to prepare implantable a hydrogel‐based supercapacitor (SC). Specially, a multinetwork conductive electrode is in situ formed by aminated‐reduced‐graphene‐oxide‐and‐methacrylic‐anhydride‐comodified sericin (SrMA/A‐rGO) sequentially cross‐linking with four‐arm polyethylene glycol succinimide carbonate and polyethylene glycol acrylate. The conductive multinetwork endows the SrMA/A‐rGO‐based SC implant an equivalent series resistance of 21 Ω cm −2 , a volumetric energy density of 26.0 µW cm −2 , and a high specific capacitance retention (over 76.4%) after long‐term charging/discharging. Two SCs connected in tandem are able to light up a light‐emitting diode for both in vitro and in vivo studies. Moreover, they can work as a direct output power source to electrically stimulate a stopped heart to start beating again. Additionally, the SC exhibits superior biocompatibility and biodegradability in vivo, and holds the value of specific capacitance above 30% 2 weeks after implantation. Thus, this work demonstrates the SrMA/A‐rGO‐based SC's potential to serve as a power storage unit for medical implants (such as a temporary pacemaker).