Fabrication and application of multifunctional conductive hydrogel film for wearable sensors via efficient freeze-thaw cycling and annealing process

Conductive hydrogel films, as integral elements of flexible sensors, hold promising applications across diverse fields. However, their cost-effective and straightforward production, ensuring both excellent mechanical properties and conductivity, remains a formidable challenge. In our research, we developed a multifunctional conductive hydrogel film using a freeze-thaw cycling-annealing method. That process applied freeze-thaw cycling to reorganize the hydrogel 's cross-linking structure and improve the polyvinyl alcohol molecules ' crystallinity through annealing. The thickness of the fabricated film was approximately 100 mu m, and the limit of detection and sensitivity for glucose were 2.82 mu M and 117.6 mu A /mM*cm 2 respectively, and the sensitivity factor during the bending process was 2.61, which demonstrated excellent biocompatibility, mechanical properties, and electrochemical properties. It also facilitates wireless, real-time electrophysiological signal monitoring and sweat glucose tracking in the human body. In summary, the freeze-thaw cycling/annealing approach simplified and accelerated hydrogel film preparation. This development is poised to resolve the intricacies of existing hydrogel film production methods and broaden the application scope of such films in wearable devices.