In-situ Preparation of Excellent Temperature Response Hydrogels with SA/PAM/PPy System and its Application in Motion Monitoring

Abstract Accurate and continuous monitoring of human body temperature is a core function of smart wearable temperature sensors. However, fabricating temperature sensors with high sensitivity and rapid response remains a challenge. Here, using the natural polysaccharide sodium alginate (SA), acrylamide (AM), and in-situ polymerization of polypyrrole (PPy), a conductive hydrogel (SA/PAM/PPy) was synthetized. It is indicated that as the pyrrole concentration increases the conductivity of hydrogel enhances from 21.3 to 67.7 mS/cm. The temperature sensitivity of hydrogels vary with temperature intervals. In 10–30℃ range, the temperature coefficient of resistance (TCR) is -1.22%/℃, increasing to -3.70%/℃ in 30–50℃ range, aligning with human body temperatures. The hydrogels also demonstrate superior responsiveness, with the temperature rise/drop response times of 0.1185 / 0.1957 s, respectively, with excellent cycling stability, maintaining stable electrical signals during multiple cycles in 25–40℃. Its application in running exercises enables effective monitoring of body temperature changes across different speeds. Overall, the developed hydrogels not only sense temperature variations but also align closely with human body temperature ranges, showing great potential in smart wearable technology.