Fully 3D-Printed Cuff Electrode for Small Nerve Interfacing

Interfacing with the peripheral nervous system is a powerful method for diagnosing and treating several diseases, such as drug-resistant epilepsy and depression. In most clinical applications, large nerves such as the vagus and the hypoglossal nerve are targeted. Large nerves carry multiple nerve fibers, and maintaining selectivity of a specific target response demands complex stimulation strategies. As the large trunks bifurcate toward their distal ends, their diameter and number of comprised fibers reduce. Consequently, interfacing small nerves can provide increased fiber selectivity. However, their small size presents challenges to the fabrication and implantation of suitable electrodes due to their fragility and constrained environments. Here, a cuff electrode that combines two-photon stereolithography and 3D inkjet printing techniques for the selective interfacing of small nerves in vivo is introduced. The device is easy to implant, and its size can be tailored for specific nerve dimensions. Its capability to record and selectively stimulate is demonstrated by targeting a locust's hind leg nerve.