Multifunctional\nHighly Sensitive Multiscale Stretchable\nStrain Sensor Based on a Graphene/Glycerol–KCl Synergistic\nConductive Network

Abstract

Stretchable\nstrain sensors have promising applications in health\nmonitoring and human motion detection. However, only a few of the\nstrain sensors reported to date have exhibited a multiscale strain\nrange and a high gauge factor simultaneously. As such, most strain\nsensors cannot be used in applications that require both high sensitivity\nand a multiscale strain range. In this work, we develop a wearable\nmultifunctional strain sensor using graphene and a new ionic conductor\nas the sensing material and Ecoflex as the encapsulant. In the ionic\nconductor, KCl and glycerol are used as the electrolyte and solvent,\nrespectively. This deformable ionic conductor connects cracked graphene\nsheets electronically, enabling the strain sensor to be stretched\nto 300% of its original length with a moderate gauge factor of 25.2.\nThe sensor can respond to various mechanical deformations including\nstretching, bending, and pressing. When attached to human body, the\nsensor can monitor large-scale strains (>50%) for joint movement\nand\nsmall-scale strains (<10%) for facial expressions and pulses. When\nstretched, the sensor also shows good sensitivity in static temperature\nsensing. Therefore, this multifunctional stretchable sensor has good\nprospect of applications in human motion detection and health monitoring.