Stretchable and self-healable electrical sensors with fingertip-like perception capability for surface texture discerning and biosignal monitoring

Abstract

Soft electronic skins (e-skins) with superior sensing performance have attracted significant attention in numerous applications. However, most of the reported e-skins have been prepared based on an inert polymer substrate without completely considering its self-healing ability; this severely limits the practical application of these e-skins. In addition, the fabrication of most of the e-skins is conducted via photolithography and other tedious processes; therefore, it is difficult to equilibrate high sensing performance and preparation simplification. Herein, a simple and general fabrication strategy of self-healable and highly sensitive electrical sensor, consisting of a sensing component, i.e. Au-deposited toothbrush-hair micro-prick arrays, and a substrate component, i.e. a P-TDI-IP elastomer obtained via the block polymerization of polytetramethylene glycol (P), 2,4′-tolylene diisocyanate (TDI), and isophorone diisocyanate (IP), is reported. The self-healable P-TDI-IP elastomer acting as a substrate endows the reported electrical sensor with an excellent self-healing capability (96% with 6 h) and an outstanding stretchability (1200%). Importantly, due to the presence of unique micro-prick arrays, the electrical sensor could detect multiaxial tactile stimuli including pressing and shearing. Moreover, this device exhibited high sensitivities (3.32 kPa⁻¹ for pressing, GF = 2.82 for shearing), the rapid response time of 25 ms, and the low detection limit of 5 Pa. Owing to these prominent properties, the electrical sensor presented anticipated abilities for distinguishing ultrafine surfaces with different roughnesses and monitoring various human motions.