Highly Elastic and Biodegradable Metallic Glass for Stretchable Disposable Electronics

Transient electronics is an emerging device system that changes physical form with time. A bioresorbable device that fully dissolves into small biocompatible molecules after achieving desired functionality is a representative example of transient electronics. This type of electronics is very effective to achieve the zero waste stream for disposable patch-type wearable devices, including electronic skin or epidermal electronics. The stretchability of biodegradable electronics is essential to maintain conformal contact with tissue or skin as dynamic mechanical motions of the body generate a relatively wide strain range of up to 55%. In this study, we highlight the metallic glass nanofilm, which by eliminating crystalline defects and correlated size effect has improved yield strain and elongation. We propose biodegradable metallic glass consisting of biocompatible and biodegradable metal elements Mg, Zn, and Ca. Excellent yield strain and elongation of nanoscale metallic glass were demonstrated compared to that of crystal structured Mg using nano tensile tests. Combining serpentine geometry and intrinsically stretchable metallic glass has highly improved overall stretchability at the device system level. Fabrication of passive and active components using the MgZnCa electrode demonstrated good electronic integratability. Integrated MgZnCa electrode as a collector electrode of triboelectric nanogenerator (TENG) showed high fatigue-resistance in cyclic deformation tests maintaining its original performance. Finally, the in-vitro cell cytotoxicity test and in-vivo implantation demonstrated the biocompatibility and biodegradation properties of the MgZnCa.