Implantable Wireless Neural Interface for Multichannel Neural Recording and Optogenetic Neuromodulation

This paper presents a low cost, light-weight, and low power consuming wireless neural interface for multichannel neural recording and optogenetic neuromodulation with 470 and 589 nm light sources and a customizable pulse generator. To enhance the light coupling efficiency between the light emitting diode (LED) and 4 x 4 array of optical fibers, microlens array is used. Measured light intensity at the tip of the fiber array is 2.812 and 1.765 mW/mm2 for 470 and 589 nm light sources, respectively. Optical fibers are assembled with 4 x 4 microlens array on a silicon die, which enables the illumination of relatively large area in the brain. To record the neural signal, two zero-drift operational amplifiers and 12-bit ADC (analog-to-digital converter) were used. The sampling frequency on each channel is 16 kHz. A ± 160 μV, 100 Hz sine wave in saline solution was successfully measured and wirelessly transmitted with the fabricated device.