Highly Transparent, Adhesive, and Mechanically Robust Eutectogel via Metal-coordination Physical Crosslinking for Reliable Flexible Strain Sensors

Eutectogels are considered to have immense application potential in the field of flexible wearable ionotronic devices because of their excellent ionic conductivity, thermal and electrochemical stability, and non-volatility. However, most existing technologies still struggle to achieve synergistic optimization of key performance indicators, such as high mechanical strength and ionic conductivity. To address this challenge, this study successfully prepared a green eutectogel material with outstanding comprehensive properties by leveraging the high solubility of glycerol in a polymerizable deep eutectic solvent (DES) composed of acrylic acid and choline chloride. The resulting eutectogels exhibited a high transparency (89%), high mechanical strength (up to 2.8 MPa), and exceptional tensile performance (up to 1385%). The fabricated flexible sensor demonstrated ideal linear sensitivity (gauge factor: 0.88), a broad response range (1%–100%), and reliable stability (over 1000 cycles), enabling the precise monitoring of human motion (e.g., finger bending and wrist rotation). The flexible strain sensor based on this eutectogel is expected to show promising prospects for medical monitoring, human-machine interaction, and industrial sensing applications.