Recent advancements in implantable bioelectronic devices have increased the demand for biocompatible energy sources with long-term electrochemical and mechanical stability. Here, we present a tough hydrogel-based supercapacitor (THBS) fiber, fabricated via a thermal drawing process (TDP), that enables the integration of all components—electrodes, electrolyte, current collectors, and encapsulation—into a single, unified, and mechanically robust fiber-shaped architecture. Through thermal/mechanical optimization and the incorporation of self-healing properties, THBS fibers exhibit durable, high electrochemical performance under dynamic, high-curvature deformations mimicking in vivo physiological motions. Despite a thickness of only a few hundred microns, they maintain mechanical and electrochemical stability. Long-term functionality was confirmed over five weeks with minimal immune response. In vivo implantation demonstrated successful LED operation in a freely moving mouse, and successful optogenetic stimulation of both central and peripheral nervous systems. These results underscore the promise of THBS fibers as next-generation, fully biocompatible energy storage devices for advanced implantable bioelectronic systems. Implantable energy devices must ensure biocompatibility and electrochemical safety. Here, the authors present a fiber-based supercapacitor with high durability and flexibility, enabling seamless implantation and reliable long-term operation.
Jeon et al. (Tue,) studied this question.