Silver nanowire/polyacrylamide/gelatin flexible stress, strain and temperature sensor

Wearable and flexible sensors with high sensitivity and repeatability are widely used in many fields. However, the problems of poor sensor stability and high cost need to be addressed. Here, we prepared flexible hydrogel sensors of gelatin, polyacrylamide (PAM) and silver nanowires (AgNWs) using ethylene glycol and water as binary solvents. The adhesion properties of PAM allow the sensor to adhere stably to the surfaces of (plastic, rubber, and metal) objects. This flexible sensor has a ability to respond accurately to signals generated by changes in temperature, stress, and strain. With a gauge factors (GF) of 1.0 at 150% strain and 1.8 at 658% GF, the sensor has a detection limit as low as 1%, demonstrating the sensor's ability to detect both large and small strains. Even when the sensor is cycled 1000 times at 1% strain, the signal peak remains within a stable range overall. In this paper, we develop a low-cost, non-toxic, wearable flexible sensor that can detect signals such as strain, pressure, human motion, temperature, and micro-expression changes.