Non-linear Effects in Hydrogel-based Chemical Sensors: Experiment and Modeling

Stimuli-responsive' or 'smart' hydrogels are capable of reversibly converting chemical energy into mechanical energy and therefore they are widely used as sensitive materials for chemical sensors. However, non-linear effects such as hysteresis and drift are observed in the swelling behavior of the hydrogels, complicating the calibration procedure for the sensor and affecting the signal reproducibility. In the present work, in order to realize pH and temperature sensors with high signal reproducibility and high long-term stable sensor sensitivity, the complicated kinetics of gel swelling/deswelling processes has been analyzed and the origin of the hysteresis non-linearities has been elucidated.