A polyacrylamide/gelatin/tannic acid-modified carbon nanotube double network hydrogel with skin temperature-triggered adhesion and high sensitivity for wearable sensors

Flexible wearable devices based on conductive hydrogels have received widespread attention. However, the poor mechanical properties, weak adhesion and low sensitivity of traditional hydrogels greatly limit their practical applications. In this study, a polyacrylamide/gelatin/tannic acid-modified carbon nanotube (PAM/gelatin/TA-CNT) double network conductive hydrogel with skin temperature-triggered adhesion and low-temperature-triggered detachment was constructed via a simple one-pot method using polyacrylamide (PAM) and gelatin as the main components, and tannic acid (TA)-modified carbon nanotubes (CNTs) as the conductive filler. The resulting hydrogel has various functions such as excellent mechanical properties, high sensitivity (GF value was 5.50), wide strain detection range and excellent fatigue resistance. Flexible strain sensors based on this hydrogel can provide real-time and stable monitoring of human physiological activities over a wide strain range. In addition, its assembly into a pressure sensor can also realize information encryption and transmission. A PAM/gelatin/TA-CNT hydrogel with skin temperature-triggered adhesion and excellent sensing properties.