Piezoresistive electronic skin based on diverse bionic microstructure

Abstract

With the introduction of micro nano structure, the performance of electronic skin (E-skin), as a flexible pressure sensor, has been significantly improved. However, most of the pre templates for constructing micro nano structure are fabricated by photolithography, which endows them with the limitation of surface microstructure and the difficulty of forming complex multi-level structures. Distinguished from the artificial micro-structured silicon template, there are abundant microstructure distributed on the surface of natural plant leaves for us to choose. The diversity of plant leaves provides more possibility for us to explore the internal relationship between the microstructure distributed on electrode surface and the performance of E-skin device. Herein, four kinds of plant leaves are selected as templates to fabricate E-skins with different bionic microstructures. The various sensing performances of four kinds of devices are evaluated through the real-time monitoring of current signal, and the device based on nerium oleander template exhibits the most outstanding performance (sensing range: 0–0.8 kPa, sensitivity: 8.5 kPa−1, detection limit: 0.001 kPa). Furthermore, quantitative indicators (radius/height and density) for the surface microstructure of E-skin are proposed to explain the performance differences between these devices. The device with fine (small values of radius/height) and high-density microstructure trends to exhibit high sensitivity and low detection limit as well as good durability. Additionally, the activating phenomenon of the E-skin during repeated compression was observed and the underlying mechanism was discussed. Finally, the E-skin based on nerium oleander template has been successfully employed to detect the subtle distinction of physiological signals in a series of fitness actions.