Ultra-Sensitive and Ultra-Stretchable Strain Sensors Based on Emulsion Gels with Broad Operating Temperature

Graphical High stretchability (more than 1000 %) and conductivity (0.67 S/m) emulsion gels were fabricated from emulsions and the introduction of glycerol endowed them with broad operating temperature (−20 to 90 °C). The emulsion gel based strain sensors showed high sensitivity (gauge factor=6.240), fatigue resistance, self-healing and adhesion properties, realizing the repeatable and accurate detection of full-range human motions. Hydrogels with mechanical elasticity and conductivity are ideal materials in wearable devices. However, traditional hydrogels are fragile upon mechanical loading and lose functions in climate change because the internal water undergoes freeze and dehydration. Herein, we synthesize stable emulsions at high and low temperatures by introducing glycerol into the W/W emulsions. Then the high-stable emulsions are used as templates to produce the freestanding emulsion gels with enhanced mechanical strength and conductivity. The introduction of glycerol endows emulsions and emulsion gels with high and low temperature resistance (−20 to 90 °C). The fabricated strain sensors based on emulsion gels show high sensitivity (gauge factor=6.240), high stretchability (1081 %), fatigue resistance, self-healing and adhesion properties, realizing the repeatable and accurate detection of various human motions. These high-performance and eco-friendly emulsion gels can be promising candidates for next-generation artificial skin and human-machine interface.