Highly Stretchable, Fatigue Resistant, Electrically Conductive and Temperature Tolerant Ionogels for High-performance Flexible Sensors.

Ionogels are ideal candidate materials for flexible sensors, but their stretchability and fatigue resistance are limited. Herein, highly stretchable, fatigue resistant, electrically conductive and temperature tolerant ionogels are investigated and further applied in fabricating high-performance flexible sensors. The ionogels consist of a poly(acrylic acid) (PAA) network and a commonly used room temperature ionic liquid (RTIL) named 1-ethyl-3-methylimidazolium dicyanamide ([EMIm][DCA]). Dually acrylated Pluronic F127 (F127DA) was utilized to crosslink PAA network and [EMIm][DCA] was physically confined in PAA network. Owing to their special crosslinking structure, the PAA ionogels are highly stretchable (>850 %), tough and fatigue resistant, and they are also conductive, transparent and temperature tolerant because of the existence of [EMIm][DCA]. On the basis of their integrated performances, the PAA ionogels were further utilized to fabricate strain sensors and pressure sensors. The ionogel-based strain sensors have high sensitivity, low response time (200 ms), wide strain sensing range (0-750%), excellent durability (>1400 cycles) and good temperature tolerance and can be applied to detect various human motions. The pressure sensors also have high response speed (256 ms) and excellent sensitivity (GF=0.73 kPa-1), which offers an opportunity to detect force generated by finger touching and water droplets.