Hydrogel-based piezoresistive pH sensors: Modeling, simulation and experimental verification

This paper presents the investigations of a novel type of piezoresistive pH sensors exploiting the chemomechanical energy conversion due to PVA/PAA hydrogel swelling. The sensor structure consists of three parts including a commercial piezoresistive pressure sensor chip, a hydrogel layer, and a rigid grid. The sensor behaviour comprising membrane deflection, membrane stress and output voltage due to the hydrogel swelling has been calculated by finite element method using ANSYS software. It has also been determined experimentally and was compared with those obtained by simulation. A relatively good agreement between caculated and measured results could be achieved.