Highly Stretchable Eutectogel for Strain Sensors and Bioelectrodes Under Extreme Environments

Eutectogels have garnered attractive interest for applications in electrochemistry, environmental science, energy storage, and flexible sensing. Emerging flexible temperature sensors demand materials with high environmental stability, robust adhesion, superior mechanical properties, certain self-healing capacities, and good transparency. Herein, deep eutectic solvent (DES), composed of acrylic acid and guanidine hydrochloride, is combined with catechol and mesoporous molecular sieves to construct a dynamic network of multiple hydrogen bonds, resulting in multifunctional gels. The eutectogel demonstrated exceptional stretchability (1680.4%, 178.12 kPa), compressive strength (70%, 760.9 kPa), fatigue resistance (no significant deviation for 10 cycles), adhesion strength (35.8 kPa), transparency (92.41%), and UV-blocking capabilities. The non-volatile nature of the DES and the formation of hydrogen bonds during crosslinking preserved the DES within the gel, enhancing its moisture retention (weight change ratio of ≈2% after 6 days). Additionally, the freezing point of gel is effectively lowered, improving its environmental stability (-70-50 °C). Based on the aforementioned characteristics, the eutectogel is applied in the field of electrocardiogram detection. This bioelectrode is capable of monitoring changes in human heart rate under extreme conditions and can be assembled with wearable devices to provide a promising solution for the diagnosis and prediction of cardiovascular disease.