Mechanically Compliant and Impedance Matching Hydrogel Bioelectronics for Low‐Voltage Peripheral Neuromodulation

Abstract In neural biointerfacing technologies, mitigating the mismatch in mechanical and impedance attributes between neural tissues and bioelectronics remains a central challenge for achieving high‐efficacy neuromodulation. Here, full‐hydrogel bioelectronics that demonstrate superior mechanical compliance and impedance matching with 3D peripheral nerves, allowing for low‐voltage vagus nerve stimulation, are reported. By precisely tuning the dimensional parameters through 3D printing, the hydrogel bioelectronics, initially in a 2D planar form in a dehydrated state, can curl spontaneously around nerves and form a seamless interface. During the hydration process, instant, and tough bioadhesion is achieved through a dry crosslinking mechanism, enabling a mechanically robust nerve‐electrode interface to resist dynamic yet vigorous deformations of the peripheral nerve systems. The as‐formed nerve‐electrode interface significantly mitigates the impedance mismatch, in favor of electrical stimulation at a threshold voltage of 10 mV, one order of magnitude lower than that of conventional metallic electrodes. The use of the hydrogel bioelectronics for successful stroke rehabilitation through low‐voltage vagus nerve stimulation in a rat model is also demonstrated.