Hydrophobic Eutectogels for High‐Humidity Environment Sensing

ABSTRACT Gels with excellent ionic conductivity and high‐humidity resistance are highly desired in practical applications due to their potential to create wearable soft electronics that maintain reliable performance under humid conditions. Herein, we designed a fully hydrophobic eutectogel by one‐step copolymerization of glycidyl methacrylate and 2‐phenoxyethyl acrylate within a hydrophobic deep eutectic solvent (DES) composed of 1‐allyl‐3‐methylimidazolium chloride and methyl 4‐hydroxybenzoate. The optimized eutectogel exhibited exceptional moisture tolerance, featuring a water contact angle > 107° and humidity‐insensitive ionic conductivity (0.10 mS·cm −1 at 90% RH). Subsequently, we fabricated a strain sensor that demonstrated stable resistance responses to multi‐scale human motions, such as finger, wrist, and elbow joint bending, under both ambient and high‐humidity conditions. This stability arose from the covalently crosslinked hydrophobic polymer network and non‐hygroscopic DES, effectively mitigating water‐induced sensing instability. The hydrophobic eutectogel sensor establishes a transformative platform for next‐generation wearables in personalized healthcare and extreme‐condition sensing.