MXene-Reinforced Antifreezing Conductive Eutectogel with Enhanced Sensing Sensitivity for Low-Temperature Wearable Sensors.

Conductive hydrogels have been widely used in bioelectronics due to their excellent flexibility, electrical conductivity, and biocompatibility. However, the water in hydrogels is prone to freezing at low temperatures, decreasing flexibility and sensing performance. In this work, a dual-network eutectogel composed of poly(vinyl alcohol) and poly(acrylic acid) is prepared by using deep eutectic solvent (DES) and MXene as the antifreezing medium and conductive component, respectively. The molecular dynamics simulations analyze the interaction of DES and HO in the networks to verify the effect of DES in eutectogel. Then the ratio of DES and HO in the networks is optimized by the mechanical properties, water loss resistance, and antifreezing properties. The eutectogel has good tensile properties (a strain of 570%), reliable repeatability, and excellent antifreezing performance (it can work at -80 °C). The introduction of MXene effectively enhances the sensitivity of the eutectogel sensor to 12.25, which is 6.5 times higher than that without MXene. The eutectogel-based strain sensor allows motion monitoring and encrypted information transmission at -30 °C. Combining the sensor with a soft gripper can also enable object grasping and size recognition. The eutectogel holds promise for the application of flexible sensors in extreme environments.