Biodegradable, breathable, flexible, and electrically modulated all-leaf capacitive electronic skin for gesture recognition and human motion monitoring

Abstract

Biodegradable, flexible, non-toxic, and disposable electronic skins (e-skins) are drawing significant attention because of their biocompatibility, outstanding sensitivity, affordability, environmental friendliness, and widespread applications in wearable electronics and flexible sensing platforms. In this study, we develop a biodegradable, disposable, sensitive, breathable, and electrically modulated e-skin using all-leaf electrodes and a dielectric layer, which is fabricated by sandwiching a dried leaf between oxidized single-walled carbon nanotube (Ox-SWCNT)/silver nanowire (AgNW)-coated leaf skeletons. As an unexplored strategy, the use of Ox-SWCNTs with ultra-high thermal conductivity improves thermal stability and conductivity in AgNW-based electrodes (4–5 times). In addition, by adjusting the concentration of Ox-SWCNTs and optimizing electrical characteristics, electrical conductivity and current pathways are tuned to modulate the sheet resistance and electrical conductivity of all-leaf electrodes. The disposable e-skin exhibits a wide sensing range (0.01–97 kPa), high sensitivity (0.86 ± 0.16 kPa−1), low limit of detection (∼10 Pa), linearity for low- and high-pressure regimes, flexibility, breathability, and biodegradability. Furthermore, the developed e-skin exhibits a wide range of sensing performances in measuring human physiological signals, exhalation, vocal cord vibrations, and motion monitoring.