Ultra-highly sensitive and self-healing flexible strain sensor with a wide measuring range based on a bilayer structure

Abstract

Flexible sensors have attracted attention for their characteristics of high tensility, bendability and deformation recovery. This paper introduces a bilayer flexible strain sensor with ultra-high sensitivity, wide measurable range and self-healing character. The strain sensor comprises a fragile upper metal film and a flexible Ecoflex/graphene substrate. The specially designed dual-channel structure allows two-stage strain detection and realizes higher detection accuracy. The gauge factor reached 136,100 in a micro strain stage of 0%–1.18%, allowing the accurate detection of weak signals from the human body. The gauge factor reached 6145 in a strain range of 1.18%–50%. After 10,000 stretching cycles, the propagation of cracks on the sensor led to large residual resistance. The sensor could self-repair quickly through simple electrical heating. The sensor has potential in the monitoring of human movement, from tiny facial expressions, speech recognition and heart beats to large-scale finger and wrist bending, and is thus promising for application to wearable devices and human–machine interaction.