A Self-Healing, Adhesive,\nand Anti-Freezing PAA/PEDOT:PSS/Nb<sub>2</sub>CT<sub>X</sub> Hydrogel\nfor Flexible Pressure Sensors and\nPhotothermal Therapy

The\nconductive hydrogels used for fabricating flexible\npiezoresistive\nsensors encounter challenges related to diminished sensing performance\ndue to limited mechanical properties. This study presents the development\nof a PAA/PEDOT:PSS/Nb<sub>2</sub>CT<sub>X</sub> hydrogel through a\nstraightforward polymerization method. The hydrogel features a cross-linked\ndual network structure abundant in hydrogen bonds, which imparts exceptional\nmechanical properties, including stable stretchability, good compressibility,\nstrong adhesion, superior self-healing capabilities, and antifreezing\ncharacteristics. With a high conductivity of 165.54 S m<sup>–1</sup>, the piezoresistive sensor based on this hydrogel demonstrates remarkable\ncompressive sensing capabilities, including a low detection limit,\na high sensitivity of 9.81, a rapid response/recovery time of merely\n200 ms, a wide sensing range, and cyclic stability exceeding 2000\ncycles. This sensor effectively detects a variety of human physiological\nactivities, ranging from large joint movements to subtle finger bending\nand swallowing. Notably, the integration of Nb<sub>2</sub>CT<sub>X</sub> nanosheets, which possess photothermal conversion characteristics,\nallows the hydrogel to heat up quickly in response to near-infrared\nlight, rendering it suitable for photothermal therapy. The combination\nof enhanced sensing performance and photothermal treatment potential\nin this sensor indicates promising applications in human health monitoring\nand adjunct therapy.