PVA/Sodium Alginate/PEDOT:PSS-Based Multifunctional Hydrogels with Rapid Self-Healing, High Stretchability, and Touch-Sensing Capability

Abstract

The development of stretchable, self-healing, conducting hydrogels is crucial in wearable electronic devices, health monitoring, strain sensing, biosensing, etc. In this study, we developed a highly stretchable, rapid self-healing, adhesive, conductive hydrogel composite containing polyvinyl alcohol (PVA), natural polymer sodium alginate (SA), poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) conductive polymer, and crosslinking agent boric acid (BA), which induces rapid gelation at the nanoscale. PVA (8 wt %)/Alg (2 wt %)/PEDOT:PSS (0.1 wt %) hydrogels show high mechanical strength and stretchability with more than 30-fold elongation (3000% without breaking) when stretched manually. The studied hydrogel shows a rapid self-healing response, which is attributed to reversible and dynamic crosslinking boron-ester (B−O−C) bonds between boric acid and PVA. The hydrogel exhibits a very high constant (e′) of the order of 109, originating from interfacial polarization arising from a highly crosslinked porous polymer nano-network. The electrical conductivity of the hydrogel is evidenced by the LED lights turning after connection. Changes in LED brightness during stretching, twisting, and release demonstrate the strain sensitivity of the PVA/Alg/PEDOT:PSS hydrogel. The hydrogel’s electrical resistance responded reversibly to applied weights, showing cyclic resistance/conductivity changes of 20%, 55%, 65%, and 80% under 50, 100, 200, and 500 g loads, respectively. These results confirm the material’s piezoresistive behavior and its potential as a pressure sensor for flexible electronic devices. By integrating electrical impedance tomography (EIT), the hydrogel was also able to distinguish between light touch and press stimuli, enabling detection of both pressure intensity and spatial distribution for applications in soft robotics and wearable electronics.