A robust conductive organohydrogel with adhesive and low-hysteresis properties for all-weather human motion and wireless electrocardiogram sensing

Abstract

Traditional conductive hydrogels often have problems, such as a limitation of the operating temperature, low adhesion and sensitivity, and unsatisfactory durability, which seriously hinder the development of conductive hydrogel sensors for practical all-weather applications. In this work, we proposed a novel multifunctional ionic conductive organohydrogel: PAM-Gly-LiCl-TA (OH-PLT). The OH-PLT hydrogel is based on a PAM polymer network containing glycerol/water with certain additives, including tannic acid and LiCl. The OH-PLT hydrogel demonstrated good mechanical properties with a strain at break of 560%, maximum breaking strength of 78 kPa, and low hysteresis of ∼10%. Meanwhile, this organohydrogel exhibited an excellent electrical conductivity (1.04 S m⁻¹) and a highest sensitivity at 150% strain (GF = 7.54). Further, OH-PLT showed a wide working window (−30 °C to 40 °C) and long-term moisture retention (>7 days) under a room environment. Moreover, it possessed strong UV resistance (98.7%) and a high level of transparency (>80%). Finally, the developed hydrogel sensor could directly adhere to skin for human motion monitoring in all weather conditions and wirelessly monitor ECG signals in performing activities. This work provides a robust and feasible organohydrogel with a strong environmental adaptability, which indicates it could be a great potential candidate for flexible sensor applications.