Optogenetic Stimulator with µLED-Coupled Optical Fiber on Flexible Substrate via 3D Printed Mount

Abstract

This paper presents the design, fabrication, and characterization of an optogenetic neural modulator using optical fiber on a flexible substrate. The optical fiber is coupled with a micro-sized light-emitting diode (µLED) by using a 3D-printed fiber mount. The optical fiber mount is 3D-printed by using direct laser writing (DLW) technology with a commercial resin, which can be used to print sub-millimeter-sized shapes with high printing speed and precision. The size of the fiber mount is 800×800×800 µm3, and the optical fiber has a diameter of 230 µm diameter and a length of 5 mm. The substrate based on polyimide (PI) ribbon cable offers biocompatibility with flexibility and mechanical properties. Under the µLED, a reflecting layer is added, further helping more light to couple to the fiber. The µLED emits blue light at 460-nm wavelength, which can excite the channelrhodopsin (ChR2) for optogenetic neural stimulation.