Electromechanics of stretchable hybrid response pressure sensors based on porous nanocomposites

Stretchable pressure sensors are a key enabler of human-mimetic e-skin technology, with promising applications in soft robotics, prosthetics, biomimetics, and biosensors. Stretchable hybrid response pressure sensor (SHRPS) is an emerging type of soft pressure sensor that employs hybrid piezoresistive and piezocapacitive responses. A unique feature of SHRPS based on barely conductive porous nanocomposite (PNC) is its exceptional pressure sensitivity which trivializes its sensitivity to lateral stretch or shear. In this work, we experimentally characterize the electromechanical responses of SHRPS under various loading conditions and provide theoretical explanations through an equivalent circuit model. The capacitance and resistance of the PNC are described by a parallel mixing law and Archie’s law, respectively. Our model can reasonably predict the responses of SHRPS. Our findings reveal that SHRPS exhibits minimal sensitivity to stretch and shear because the hybrid response mechanism is activated only under compression. The effects of PNC-electrode contact impedance and fringe effects are discussed.