Highly stretchable and self-healable ionogels with multiple sensitivity towards compression, strain and moisture for skin-inspired ionic sensors

Ionic skin (I-skin) is an emerging skin-inspired sensor that has received increasing interest for the next-generation wearable electronics. However, profound challenges for I-skin remain in achieving multiple signal responses (e.g., strain, pressure, and humidity) and self-healability to fully mimic human skin. Herein, a Fe3+ ion-coordinated poly(acrylic acid) ionogel (PAIFe) with high stretchability, extreme temperature tolerance, and self-healing capability is prepared by a dynamic ionic cross-linking strategy. The ionic coordination in the PAIFe contributes to the formation of a highly dynamic network, achieving its high-efficient and reliable self-healing performance even at a low temperature of −20°C. Using of 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]) as the solvent achieves a wide-temperature tolerance of the PAIFe under low and high temperatures. More interestingly, a humidity sensing function is realized in the PAIFe by skillfully utilizing the hygroscopic properties of [BMIm][BF4]. The resultant PAIFe is proof-of-concept demonstrated as a deformation-tolerant ionic conductor in a skin-inspired ionic sensor, showing a variety of sensory capabilities towards compression, strain and humidity.