A conductive and anti-freezing gelatin-PAA-based organic hydrogel (PC-OH) with high adhesion and self-healing activities for wearable electronics

In the realm of flexible wearable electronics and interactive technologies, the adhesive and touch-sensing properties of materials play a crucial role, especially soft ionic conductors. However, these materials face several challenges in practical application, including structural damage, loss of functionality, and device stratification, particularly in extreme environments. To address this, a novel multifunctional organic hydrogel, termed PC-OH, was designed and prepared to enhance its performance. The hydrogel exhibits self-adhesion, self-healing, anti-freezing, anti-drying, and conductive capabilities. It demonstrates outstanding self-adhesive properties on skin surfaces under air (approximately 967 J/m2) or underwater (approximately 428 J/m2) conditions, with high transparency (visible light transmittance of 87 %), anti-freezing capability (−60 °C), anti-drying capability (60 °C), rapid self-healing in air or water (within 4 s), long-term stability over a wide temperature range (−20 °C to 60 °C for up to 7 days), high extensibility (up to ∼1700 % at 60 °C and ∼1200 % at −20 °C), and conductivity over a broad temperature range (ionic conductivity of 1.93 S m−1 at 60 °C and 3.13 × 10-3 S m−1 at −30 °C). Based on these properties of PC-OH hydrogel, we constructed a capacitive touch system to demonstrate its practical application. The touch panel features high stretchability, transparency, anti-freezing, anti-dehydration, self-healing, and self-adhesive human–machine interface capabilities, enabling integration with the skin under abnormal temperature and humidity conditions. Tasks such as writing text, drawing graphics, and playing electronic games validated the significant potential of the hydrogel in touch panels, providing a solution to long-standing issues of adhesion and tactile sensing.