Contact Piezoresistive Sensors Based on Electro-Polymerized Polypyrrole and a Regulated Conductive Pathway

The performance of contact resistive pressure sensors heavily relies on the intrinsic characteristics of the active layers, including the mechanical surface structure, conductivity, and elastic properties. However, efficiently and simply regulating the conductivity, morphology, and modulus of the active layers has remained a challenge. In this study, we introduced electro-polymerized polypyrrole (ePPy) to design flexible contact piezoresistive sensors with tailored intrinsic properties. The customizable intrinsic property of ePPy was comprehensively illustrated on the chemical and electronic structure scale, and the impact of ePPy's intrinsic properties on the sensing performance of the device was investigated by determining the correlation between resistivity, roughness, and device sensitivity. Due to the synergistic effects of roughness, conductivity, and elastic properties of the active layers, the flexible ePPy-based pressure sensor exhibited high sensitivity (3.19 kPa^-1, 1-10 kPa, R² = 0.97), fast response time, good durability, and low power consumption. These advantages allowed the sensor to offer an immediate response to human motion such as finger-bending and grasping movements, demonstrating the promising potential of tailorable ePPy-based contact piezoresistive sensors for wearable electronic applications.