Soft Materials for Sensor Applications

Hydrogels are highly cross-linked, hydrophilic, and water-swellable polymeric networks which can be synthesized by the chemical or physical cross-linking of hydrophilic molecules. They can recognize the impact of external stimuli and can produce electrical, thermal, and optical signals to form sensors and diagnosis tools. Depending upon their physical or chemical structure, flexibility, biocompatibility, durability, and sensitivity, they can be integrated into different systems. This chapter mainly highlights the different types of physiochemical sensing mechanisms and recent advances in different types of sensors, such as temperature sensors, pressure/strain sensors, gas sensors, pH/ionic strength sensors, and humidity sensors. Moreover, some important biomedical applications of hydrogel-based sensors are highlighted. In addition to the recent advances and developments in hydrogel-based sensors, some drawbacks of conventional hydrogel sensors and their future perspectives are also disclosed in this chapter.