Design, simulation and experimental characteristics of hydrogel-based piezoresistive pH sensors

Abstract

This paper presents the investigations of a novel type of piezoresistive pH sensors exploiting the chemo-mechanical energy conversion due to hydrogel swelling. pH-sensitive poly(vinyl alcohol)-poly(acrylic acid) (PVA-PAA) hydrogel is used for this aim. The pH sensor has been designed including a commercial piezoresistive pressure sensor chip, a hydrogel layer, and a rigid grid. Behaviour of pH sensor under swelling of polymer hydrogel has been simulated using finite element method (ANSYS). The sensor simulations have been performed using the experimental material parameters of PVA-PAA hydrogel. The sensor characteristics including the silicon diaphragm deflection and output voltage have been measured. There were good relative agreements between simulations and experimental results.