A Flexible Sensor Based on Double-Network Structure Hydrogel with High Conductivity and Versatility Can Be Used for Flexible Electronic Devices

Abstract To meet the growing demand for flexible wearable sensors, this paper constructs a highly conductive composite hydrogel with a dual-network structure using poly(vinyl alcohol) (PVA), polyacrylamide (PAM), borax, polypyrrole (PPy), and ferric chloride (FeCl3) as raw materials. Through the construction of an interpenetrating dual-network and various dynamic interactions, the mechanical and sensing properties are significantly optimized. The resulting hydrogel exhibits excellent tensile strength (0.12 MPa) and elongation at break (620%), along with a high conductivity of up to 6.56 S/m and a gauge factor (GF) reaching 13.65 within a wide strain range (0–400%). Beyond sensing, the hydrogel also functions as a solid-state supercapacitor (specific capacitance of 62.25 F/g) and a triboelectric nanogenerator (open-circuit voltage of 63.65 V, short-circuit current of 10.08 μA), demonstrating multifunctional applicability. The aforementioned performance metrics demonstrate excellent capabilities, proving that a single hydrogel formulation through a rational multicross-linked network design can meet the performance requirements of various flexible electronic devices, thereby offering a material design strategy for the miniaturization and integration of wearable devices.