Stretchable anti-freeze deep eutectic solvent (DES) gels for low-temperature wearable soft sensors

Abstract

Deep eutectic solvents (DES) exhibit comparable thermal and chemical stability to ionic liquids, coupled with excellent ionic conductivity. Moreover, they boast a higher degree of safety owing to lower toxicity and increased accessibility. Hence, the utilization of DES in gel preparation emerges as an effective solution to address the challenges associated with the inadequate stability of traditional hydrogels and the heightened toxicity of gels composed of ionic liquids. In this paper, eutectogels with excellent low-temperature sensing properties were prepared by using methacrylic acid (MAA) and pyrrole (Py) as monomers and DES as solvent. The eutectogel exhibits excellent sensing capability, with a gauge factor reaching 5.21. Additionally, DES prepared using choline chloride and urea endows the eutectogel with good freeze resistance, enabling sensing at −20 °C while maintaining stability. Moreover, the eutectogel accurately monitors changes in environmental temperature, providing a promising material for temperature-measuring flexible wearable sensor applications.