Fully biocompatible, thermally drawn fiber supercapacitors for long-term bio-implantation
Sungha Jeon, Hyeonyeob Seo, Yeji Kim, Young In Choi, Youngbin Lee, Youngmin Jung, Somin Lee, Jung Tae Lee, Seongjun Park
Abstract
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.