Reversible electroadhesion induced through low ion concentration migration for biomedical applications

Reversible adhesions have exhibited a great potential in the biomedical field. Here, we designed a reversible electroadhesion between anionic κ-carrageeenan hydrogel and physiological saline-based nonionic polyacrylamide hydrogel through the low and controllable ion migration. A robust adhesion was obtained between the hydrogel pairs via a direct current (DC) of 10 V. Upon the application of a reverse voltage, the pair could be effortlessly and rapidly detached. We elucidated the mechanism of reversible electroadhesion through electrochemical analysis, attributing the adhesion to the formation of double ion layers between the adhesive interfaces under the electrical field and pH variation. When a reverse voltage was applied, the adhesion strength was dropped lower than 0.1 kPa and the detachment was occurred due to the disruption of the double ion layer by ionic migration and even diffusion. Moreover, the adhesion system demonstrated outstanding electrochemical stability, with less than a 7 % variation in charge storage capability after 1000 cycles. The proposed strategy paves the way for developing high-performance adhesion hydrogels with electrically controllable functions, which are indispensable for various emerging fields like tissue repair and soft biomedical applications.