Fabrication and Sensing Performance of Body Temperature Triggered In Situ Curing Deep Eutectic Gel Electrodes

Aiming at the critical limitations of commercial Ag/AgCl electrodes and conventional hydrophilic polymer networks, such as dehydration failure, freezing at low temperatures, and poor signal acquisition quality in open and complex physiological environments, this study proposes an innovative strategy utilizing a deep eutectic system to regulate in situ polymerization. A hydrophobic LA-Thymol deep eutectic matrix was constructed using lipoic acid (LA) as the hydrogen bond acceptor and thymol as the hydrogen bond donor, successfully reducing the melting point of LA within the eutectic system to approximately 33 ℃. A low viscosity precursor was prepared at room temperature by incorporating a small amount of ethanol, polyethylene glycol diacrylate (PEGDA), and PEDOT∶PSS aqueous dispersion. Upon application to the skin, this system requires no ultraviolet light or high temperature assistance; relying solely on the physiological body temperature of 37 ℃, it spontaneously triggers the in situ ring opening polymerization of LA, forming a highly conformal PP-DEG flexible sensing electrode. The results demonstrate that the deep eutectic gel achieves a high conductivity of 89.6 S/m and exhibits excellent mechanical and adhesive properties, along with outstanding anti freezing and long lasting moisturizing characteristics. In vitro cytotoxicity, antibacterial, and antioxidant evaluations confirm the exceptional biocompatibility and tissue safety of this electrode. In the verification of surface electromyography signal acquisition, the electrode exhibits extremely low contact impedance and a high static signal to noise ratio of 34.40 dB. Furthermore, it maintains excellent anti baseline drift capability under vigorous motion conditions, demonstrating broad application prospects in the field of long term flexible wearable physiological monitoring.