Polydopamine-triggered adhesive and conductive hydrogel for Morse code communication at polar environments

Flexible electronics have been extensively explored for health monitoring and soft robotics. However, conventional hydrogels are inevitably frozen in polar environments and easily dehydrated, and have weak surface adhesion. Inspired by the natural mussel adhesive mechanism, we designed a polydopamine-polyacrylamide-LiCl (PPL) hydrogel with high electrical conductivity, high stretchability, and strong surface adhesion under low-temperature conditions. The PPL hydrogel exhibits robust adhesion (68.8 kPa), high electrical conductivity (384 S m−1 at room temperature, and 26 S m−1 at −40 °C), superior stretchability (1200%), and cycling stability (3000 cycles). The hydrogel sensor can accurately measure human joint movements, making them suitable for use in information encryption and decryption through Morse code even in polar environments (−60 °C). Further research in this area can lead to innovative solutions for communication and health monitoring in extreme conditions.