A 3D-Printing-Based Optogenetic Neural Stimulator Integrated With Three Neural Recording Channels

This paper presents an optical neural modulation device integrated with neural recording channels. While most optogenetic devices are fabricated using microfabrication techniques, this device is produced primarily using 3D printing, eliminating the need for complex microfabrication processes. The device largely comprises two layers: one for placing and connecting a light-emitting diode (LED) and another for integrating recording channels, both of which are fabricated using 3D printing based on two-photon polymerization (2PP) technology. The LED is placed on the 3D-printed substrate with conductive material positioned underneath and electrically connected with solder balls. The recording-channel layer has grooves to accommodate three recording channels made of platinum wires. The LED and recording layers are aligned and assembled using 3D-printed holes and trenches on each substrate layer. The device properties are characterized, including electrochemical impedance spectroscopy (EIS) of each recording channel. Finally, the device is implanted into the brain of a mouse, and neural signals are recorded while being stimulated optically with the same device.