Self-Adhesive Wearable Strain Sensors Based on Transparent, Tough, Antibacterial, Self-Healing Polymeric Eutectogels

The inherent limitations of hydrogels, including susceptibility to failure due to water loss or freezing, and the limitations of ionogels, including cost and environmental impact, restrict their applications in wearable sensor technologies. Eutectogels prepared using poly deep eutectic solvent (PDES) have emerged as the most promising candidates for wearable sensors due to their economical nature, environmentally friendly nature, and good temperature tolerance characteristics. The necessity for self-adhesion as a sensor property is highlighted by the occurrence of false signals caused by detached sensors under complex maneuvers. Herein, eutectogels were synthesized through the incorporation of gallic acid (GA) and hydroxyethyl methacrylate (HEMA) as multifunctional hydrogen bond donors in combination with choline chloride (ChCl) as hydrogen bond acceptors, referred to as the HEMA-ChCl-GA eutectogels. Their adhesive strength was up to 2.6 MPa for a variety of materials, including glass, polyvinyl chloride, wood, and pig skin, which could lift a 20 kg weight without separation. In addition, HEMA-ChCl-GA eutectogels exhibited exceptional mechanical properties, including remarkable stretchability (900%), high strength (4.18 MPa), high toughness (22.41 MJ/m3), and loading 4 kg weight (8000 times its own weight) without fracture. It demonstrated the capacity to recognize a range of human motions, which highlights its potential as a wearable sensor.