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

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.