A Self-Healing, Adhesive, and Anti-Freezing PAA/PEDOT:PSS/Nb2CTX Hydrogel for Flexible Pressure Sensors and Photothermal Therapy

The conductive hydrogels used for fabricating flexible piezoresistive sensors encounter challenges related to diminished sensing performance due to limited mechanical properties. This study presents the development of a PAA/PEDOT:PSS/Nb₂CT_X hydrogel through a straightforward polymerization method. The hydrogel features a cross-linked dual network structure abundant in hydrogen bonds, which imparts exceptional mechanical properties, including stable stretchability, good compressibility, strong adhesion, superior self-healing capabilities, and antifreezing characteristics. With a high conductivity of 165.54 S m^–1, the piezoresistive sensor based on this hydrogel demonstrates remarkable compressive sensing capabilities, including a low detection limit, a high sensitivity of 9.81, a rapid response/recovery time of merely 200 ms, a wide sensing range, and cyclic stability exceeding 2000 cycles. This sensor effectively detects a variety of human physiological activities, ranging from large joint movements to subtle finger bending and swallowing. Notably, the integration of Nb₂CT_X nanosheets, which possess photothermal conversion characteristics, allows the hydrogel to heat up quickly in response to near-infrared light, rendering it suitable for photothermal therapy. The combination of enhanced sensing performance and photothermal treatment potential in this sensor indicates promising applications in human health monitoring and adjunct therapy.