Construction of Conductive Polymer Coatings onto Flexible PDMS Foam Composites with Exceptional Mechanical Robustness for Sensitive Strain Sensing Applications

Abstract

Flexible piezoresistive-sensing materials with high sensitivity and stable sensing signals are highly required to meet the accurate detecting requirement for human motion. Herein, a conductive poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) / polydimethylsiloxane foam (P:P@p-PSF) composite with strong interfacial action is designed. The porous structures and good interface combination not only show outstanding mechanical flexibility and reliability but also possess high sensitivity at a relatively wide strain range. The P:P@p-PSF sensor achieves extreme sensitivity (Gauge Factor) of 6.25 in the subtle strain range of 1%–8%. Furthermore, the sensor forms a highly interconnected conductive network induced by the serious deformation of elastic-interconnect pores, thus providing extremely sensitive sensing behavior for a relatively wide strain range (97.4% resistance change rate at 60% compressive strain). Moreover, the sensor presents repeatable stability and good thermal adaptation, which would meet the critical requirements of subtle vital signs, human motion monitoring, and so on. This work supplies insight into the design of a new flexible sensor material to overcome the weak interface problem and the flexible mismatch between conductive filler and matrix, showing great application potential in the field of electronic skin.