Highly adhesive, anti-freezing and flexible eutectogel sensor for monitor human motions and gesture recognition

Conventional hydrogel-based flexible sensors have attracted considerable attention owing to their excellent biocompatibility and mechanical flexibility, but their insufficient environmental stability like freezing at subzero temperatures and solvent evaporation, will cause conductivity disruption and mechanical degradation. Herein, we employed a choline chloride–ethylene glycol deep eutectic solvent (DES) as the functional medium and utilized catechol-Fe³ ⁺ coordination to catalyze the rapid generation of free radicals from ammonium persulfate, thereby successfully fabricating a multifunctional DEAP eutectogel that integrates anti-freezing, water retention, high adhesion, and a broad sensing range. The resultant gel exhibits a wide strain-sensing window (fracture strain > 500%), high sensitivity (GF = 3.31), fast response-recovery characteristics (90 ms), and high conductivity (1.68 S/m). Meanwhile, the DES effectively confines free water within the network, imparting long-term water retention and strong adhesion to various substrates, with only an 18.79% decrease in adhesive strength after ten adhesion cycles. Low-temperature tests show that the gel has a glass transition temperature below −40 °C, and no ice crystals are formed even after storage at −20 °C for 24 h, preserving an intact conductive pathway for reliable strain sensing at cryogenic conditions. Practical application verifications confirm that the eutectogel can stably and repeatedly monitor multi-joint human motions and gesture recognition, indicating its great potential in wearable flexible sensing and flexible electronics even under low-temperature. Download: Download high-res image (249KB) Download: Download full-size image