One-Pot Ultrafast Fabricating of MXene-Based Conductive Hydrogel for Dual Strain-Temperature Sensors with Wide Temperature Tolerance

MXene-based conductive hydrogels are promising for flexible electronics. However, due to the oxidation susceptibility of MXene nanosheets and their weak interactions with the hydrogel matrix, fabricating stable, robust, and highly conductive hydrogels for multifunctional sensors remains challenging. In this work, lignosulfonate sodium (LS) is employed as a dispersant to effectively stabilize the oxidative state of Ti 3 C 2 T x MXene. By utilizing a low dosage of the ammonium persulfate (APS) initiator and the heat-insulating property of glycerol, radical polymerization of acrylic acid (AA) monomers is rapidly initiated, enabling the rapid preparation of conductive LS–MXene/polyacrylic acid (PAA) hydrogels within minutes. The as-prepared LS–MXene/PAA hydrogel exhibits outstanding mechanical flexibility, antifreezing capability, high electrical conductivity (0.23 ± 0.004 S/m), strain sensitivity, and photothermal characteristics. Leveraging this hydrogel, a high-performance strain sensor was developed, featuring excellent sensitivity (gauge factor = 3.64), a broad response range (10–700%), and a rapid response time (200 ms), enabling precise monitoring of resistive signals during human body movements. Furthermore, due to MXene’s superior photothermal conversion ability, the LS–MXene/PAA hydrogel demonstrates self-sensing functionality by tracking real-time resistance changes under simulated solar irradiation. Additionally, the flexible LS–MXene/PAA temperature sensor accurately detects temperature variations across a wide range, with thermal sensitivities of −2.27%/°C (10–25 °C), −0.92%/°C (25–60 °C), and −0.26%/°C (60–85 °C). Notably, it achieves a temperature resolution of 0.2 °C in the human body temperature range, making it an effective fever-monitoring tool. These attributes highlight the LS–MXene/PAA hydrogel’s potential for developing dual-function strain and temperature sensors in wearable electronics.