Bioinspired Microstructured Conductive Adhesive Hydrogel with Electronic–Ionic Dual Networks for Robust Health Monitoring on Dry/Wet Skin

Hydrogels with an electronic–ionic dual conductive network, excellent dry/wet adhesion, and superior biocompatibility are favorable in the fields of bioengineering and health monitoring. Although various conductive and adhesive hydrogels have been developed, single adhesion strategies face limitations in complex environments. Here, we propose a surface-microstructured conductive and adhesive hydrogel (MSCAH) that combines the material-inherent chemical adhesion with physical adhesion introduced by the biomimetic microstructures, achieving an adhesive strength of 10.39 kPa at wet surface. An electronic–ionic dual conductive network is formed by uniformly distributing PEDOT:PSS in the PDA–PAM hydrogel, improving the conductivity to 2.27 S/m. The synergistic adhesion mechanism studies show that chemical adhesion dominates the adhesion strength on dry surfaces; on wet surfaces, liquid self-splitting and self-sucking introduced by the microstructures are the main reasons for enhanced adhesions. The enhancement effect is dependent on the surface conditions and microstructure size. Finally, the application of MSCAH in ECG signal monitoring on both dry and wet human skin is studied. Compared with commercial gel electrodes, MSCAH exhibits more stable and accurate signals on watery and oily skins. The MSCAH with improved adhesion strength and signal stability on wet skin provides an effective strategy for bioelectronics and portable health monitoring devices.