Water-triggered self-wrapping and immobilization of an all-organic hydrogel-based cuff electrode

A cuff-type electrode that curls and self-immobilizes upon exposure to moisture was developed entirely from organic materials. The device consists of polyvinyl alcohol hydrogel sheets and a sandwiched carbonized knit electrode, with one hydrogel layer pre-stretched. In its dry, flat state, the electrode allows easy insertion beneath tissue structures and curls within 30 s upon application of saline, thereby improving the safety and efficiency of electrode placement during surgery. By tuning the osmotic pressure, thickness, and pre-strain of the hydrogel layer, the curled inner diameter was reduced to as small as 0.4 mm. The swelling-induced folding force ensured secure fixation while accommodating dynamic changes in tissue size. In vivo experiments in porcine and mouse models demonstrated successful vagus nerve and muscle stimulation, confirming the viability and functional performance of the proposed electrode design.