gms | German Medical Science

Objective: We describe a modular electronic system for the rapid development and testing of high-density penetrating microelectrode arrays. The system is designed for electrical recording and stimulation at cellular resolution in three-dimensional neural structures. This penetrating electrode technology may be useful for future retinal and cortical implants for vision restoration.

Materials and Methods: The modular system consists of the following. An interchangeable custom-fabricated 256-channel electrode array with variable pitch is fabricated using two-photon polymerization-based 3D printing on a borosilicate glass substrate. This array mates with an underlying printed circuit board via two 128-channel connectors for recording and stimulation. This system is contained in a wet lab-friendly aluminum housing in which small pieces of neural tissue will be pressed against the penetrating electrodes for ex vivo experiments. The modular design makes it possible to test electrode arrays of variable specifications such as height (<130 μm), diameter (>5 μm), pitch (>20 μm), and sharpness.

Results: Prior work suggests that this system will permit ex-vivo retinal recording and stimulation at cellular resolution. This work includes a proof-of-principle recording of spontaneous activity from rat retinal ganglion cells (RGCs) with electrodes fabricated directly on a planar silicon-based microelectrode array. In addition, electrode penetration into the primate retina with and without removal of the internal limiting membrane was assessed using two-photon microscopy.

Discussion: Future work with this modular system will focus on 3D recording and stimulation of RGCs in both the peripheral and central retina with the goal of developing high resolution epiretinal devices for vision restoration.

Acknowledgment: Supported by the Wu Tsai Neurosciences Institute, NIH NEI R01-EY021271 and R01-EY032900.

* C, Baum and P.Vasireddy contributed equally to the publication.