A nerve-adhesive stretchable electrode for stable neural signal recording and stimulation

Achieving long-term stable monitoring of neural signals and on-demand feedback electrical stimulation in a closed-loop manner is essential for personalized diagnosis and treatment of neurological disorders. In addition, stiffness of tissue-interfacing electrodes utilized during bidirectional signaling operations should be mechanically adaptive to the peripheral nerves for preventing undesired tissue compression. However, challenges remain associated with absence of tissue adhesion and cyclic stretching durability of the conventional soft electrodes, leading to unstable device–tissue interactions. Here, we developed a nerve-adhesive stretchable electrode (NSE) that is capable of stably monitoring sensory neural signals and electrical modulation. The NSE consists of a tough self-healing polymer substrate, an ultrathin stretchable polyimide-Au-polyimide electrode, and a mussel-inspired wet tissue-adhesive hydrogel layer (alginate conjugated with boronic acid, Alg-BA). The Alg-BA enabled the NSE to be reliably attached to the sciatic nerve of a rat, while significantly improving its signal-to-noise ratios. In addition, the dynamic stress relaxation of the NSE was highly beneficial for mechanical adaptation to the nerve, featuring the long-term tissue safety even after implantation for eight weeks. The synergistic use of tissue-adhesive materials coupled with the stretchable electronic devices would provide a great opportunity to develop the advanced neural prostheses.