Slide-Ring Based Hydrogel Sensors with Extreme Wide Temperature Adaptability Toward Winter Swimming Sensing Application.

Conductive hydrogels have significant application prospects in the field of flexible wearable sensors. However, there are still challenges to stably apply conductive hydrogels in extreme environments and various aqueous conditions. To enable the application of conductive hydrogels across a wide temperature range and in multiple environments, it is necessary to consider comprehensive properties such as anti-swelling ability, flexibility, self-adhesiveness, stable linear sensing, and certain durability. This paper proposes the preparation of conductive hydrogels using 2-methoxyethyl acrylate, N-allylthiourea monomers, and polyrotaxane based cross-linkers. The synergistic effect of multiple hydrogen bond interactions within the hydrogel networks ensures its stability in various environments, while the polyrotaxane based sliding ring structure effectively alleviates stress concentration. The introduction of phytic acid endows the hydrogel with water retention capabilities. Notably, this hydrogel exhibits good linear stability, and the abundant hydrogen bonding allows it to maintain stability and usability at high temperatures (50 °C) and low temperatures (-42 °C). The strong hydrogen bonding between thiourea, ether groups, and water molecules enables it to function normally underwater, particularly in a seawater environment at 2 °C for winter swimming application. Therefore, the designed hydrogel shows great potential for wearable flexible sensors in extreme and diverse environments.