Zwitterionic Eutectogel-Based Wearable Strain Sensor with Superior Stretchability, Self-Healing, Self-Adhesion, and Wide Temperature Tolerance

Ionic conductive eutectogels have great application prospects in wearable strain sensors owing to their temperature tolerance, simplicity, and low cost. Eutectogels prepared by cross-linking polymers have good tensile properties, strong self-healing capacities, and excellent surface-adaptive adhesion. Herein, we emphasize for the first time the potential of zwitterionic deep eutectic solvents (DESs), in which betaine is a hydrogen bond acceptor. Polymeric zwitterionic eutectogels were prepared by directly polymerizing acrylamide in zwitterionic DESs. The obtained eutectogels owned excellent ionic conductivity (0.23 mS cm–1), superior stretchability (approximately 1400% elongation), self-healing (82.01%), self-adhesion, and wide temperature tolerance. Accordingly, the zwitterionic eutectogel was successfully applied in wearable self-adhesive strain sensors, which can adhere to skins and monitor body motions with high sensitivity and excellent cyclic stability over a wide temperature range (−80 to 80 °C). Moreover, this strain sensor owned an appealing sensing function on bidirectional monitoring. The findings in this work can pave the way for the design of soft materials with versatility and environmental adaptation.