Hydrogel-Based Sensor Devices

Sensor devices integrate physical and digital systems for real-time monitoring in healthcare, agriculture, and environmental sectors. Meeting rising demands requires enhanced sensitivity, durability, and compatibility. Hydrogels—hydrophilic, biocompatible, stimuli-responsive, and selective—serve as adaptable sensing platforms. This chapter analyzes structural properties governing hydrogel sensing efficacy. It explores optical, electrochemical, and mechanical mechanisms for transducing stimuli like pH, temperature, and analytes into measurable signals. Fabrication methods, including photopolymerization and 3D printing, enable tailored designs for wearable health monitors, precision agriculture, and pollution detection. Correlating hydrogel properties to performance establishes design principles for optimizing sensitivity and selectivity. Challenges such as spatial inhomogeneity, stability under variable conditions, and biocompatibility validation are critically addressed. This chapter highlights hydrogels' transformative role in next-generation sensors.