Conductive and Robust Cellulose Hydrogel Generated by Liquid Metal for Biomedical Applications

The synthesis of cellulose hydrogels, renowned for their environmentally friendly and sustainable attributes, has gained considerable attention, especially when compared to the synthesis of polymer-based hydrogels. Here, we introduced a particle model of liquid metals into cellulose hydrogel matrices (LMCs) to provide a large surface area, facilitating the release of Ga ions. Through the release of gallium ions into the hydrogel nature, these liquid metal particles introduced additional ionic cross-linking. This enhanced cross-linking mechanism triggered a more substantial hydrogel frame, resulting in an 18-time increase in modulus and a 21-time enhancement in surface hardness compared to pristine cellulose hydrogel. In addition, the mechanical robustness of the LMC was evident as it sustained up to 80% compression and retained its structural integrity after performing 20 cycles of compression. The enhanced mechanical attributes of the LMC facilitated a unique compression-dominated contact among the liquid metal particles, thereby offering an improvement in the electrochemical properties. Also, the particles can promote the electrochemical properties due to intrinsic conductive behavior. The enhancement in the electrochemical properties allowed the LMC to be a biosensor for detecting glucose and maltose. Last, the mechanical responsiveness and enhanced electrochemical properties rendered the LMC proficient in accurately monitoring physiologic signals. This study opens up the versatile use of electrochemically conductive and robust cellulose hydrogels with the aid of liquid metal particles.