Skin-Adhesive Conductive Hydrogel With Potential for Flexible Wearable Sensor Associated With Sarcopenia

An adhesive conductive hydrogel (ACH) is developed based on a polyacrylamide–poly(ethylene glycol) diacrylate (AAm@PEGDA) matrix functionalized with polydopamine (PDA) and poly(3,4-ethylenedioxythiophene):polystyrenesulfonate (PEDOT:PSS), aiming for application as a flexible electronic bio-interface (EBI). ACH features a porous structure with a swelling ratio of approximately 300% in artificial sweat and maintains breathability approximately 2.5 times longer than conventional PEDOT:PSS-based conductive hydrogels (CHs). It exhibits tunable mechanical properties (2.5–10 MPa), excellent elasticity, and strong skin adhesion (~1 mN). Electrical conductivity is significantly enhanced through post-treatment in deionized water, reaching 3.66 × 10⁻⁵ S/m—about 345 times higher than the commercial adhesive conductive hydrogel sample. This aqueous treatment provides a more biocompatible alternative to organic solvents such as dimethyl sulfoxide. Surface electromyography (sEMG) measurements demonstrate a signal amplitude of 0.2836 V and a signal-to-noise ratio (SNR) of 12.46 dB, showing comparable performance to PEDOT:PSS hydrogels (11.4 dB) despite the incorporation of PDA for enhanced adhesion. The ACH shows no cytotoxicity or sensitization responses in biological evaluations. Its high moisture retention supports ionic transport during long-term wear and offers potential for sweat-based biomarker sensing. These properties suggest ACH is well-suited for use as an EBI and holds strong potential for next-generation wearable electronics and sEMG monitoring applications.