Poromechanical modeling of a stimuli-responsive hydrogel in a chemical sensor with force compensation

In the category of smart materials, stimuli-responsive hydrogels are of great interest due to their significant stimuli-induced volume change. This ability inspires their application in sensors, actuators, and other electronic devices. In this work, a chemo-thermo-responsive hydrogel is used in a chemical sensor setup, where the thermal stimulus compensates for the gel deformation caused by the chemical stimulation. By keeping the hydrogel volume constant, creep and relaxation effects can be largely suppressed. Since diffusion processes are slow, the desired volume constancy cannot be achieved immediately at all individual points of the hydrogel. To predict the sensor response, we implement a chemo-thermo-poromechanical model in COMSOL Multiphysics ® to simulate the swelling-deswelling behavior of the hydrogel in the sensor. The numerically computed swelling kinetics benefit the further investigation of the sensor optimization.