Hydrogel‐Based Capacitive Sensor Model for Ammonium Monitoring in Aquaculture

Monitoring aquaculture water quality, especially ammonium levels affecting fish health, is challenging due to limitations in traditional methods. This study presents an innovative capacitive sensor with an ionic hydrogel transducer for real‐time ammonium concentration monitoring. The sensor operates through ammonium‐induced dissociation in the hydrogel, causing osmotic pressure changes and altering electrode capacitance. Analytical formulations verified by finite element simulations demonstrate the sensor's ability to detect varying ammonium levels. Detailed analysis covers diffusion kinetics, swelling behavior, stress distributions, voltage variations, and ion equilibrium concentrations. The findings show a 20% increase in capacitance change within 200 s, even with a 3 μM ammonium concentration exposure. Additionally, the capacitance change plateau at ammonium levels exceeding 1 mM. The presented concept offers a promising and cost‐effective approach to addressing the limitations of traditional methods, paving the way for future research and development in real‐time water quality monitoring in aquaculture systems.