Development of piezoresistive poly(ɛ-caprolactone) sensor with unique flexibility and sensing performance for rehabilitative application

Abstract

ABSTRACT Piezoresistive sensor is applied extensively in rehabilitative monitoring, to help with patients’ physical and mental health recovery. However, the manufacturing complexity of hierarchical structure in sensing element remains a major limitation to piezoresistive sensor. Here, we report a scalable and simple method for the preparation of piezoresistive sensing element. Based on biocompatible poly(ɛ-caprolactone) (PCL), uniaxial cold stretching resulted in a flexible sheet-like element with unique hierarchical geometries comprising highly aligned multiscale ridges on sheet’s double sides. This leads to higher mechanical elasticity of the hierarchitectured PCL element and enhanced resistance against plastic deformation due to the improved Young’s modulus. Further assembly of the piezoresistive sensor demonstrates a wide detection range of 25–4.7 × 104 Pa with rapid response and the high sensitivity of 1.37 kPa−1 at small pressure loadings. The sensor shows successful application in the monitoring physiological signals including pulse, speaking, face expression and limb motion.