A 1024-channel 6 mW/mm² optical stimulator for in-vitro neuroscience experiments

Abstract

Recent optical stimulation technologies allow improved selectivity and have been widely used in neuroscience research. This paper presents an optical stimulator based on high power LEDs. It has 1024 channels and can produce flexible stimulation patterns in each frame, refreshed at above 20 Hz. To increase the light intensity, each LED has an optical package that directs the light into a small angle. To ensure the light of each LED can reach the lens, the LEDs have been specially placed and oriented to the lens. With these efforts, the achieved power efficiency (defined as the mount of LED light power passing through the lens divided by the LED total power consumption) is 5 × 10(-5). In our current prototype, an individual LED unit can source 60 mW electrical power, where the induced irradiance on neural tissues is 6 mW/mm(2) integrating from 460 nm to 480 nm. The light spot is tunable in size from 18 μm to 40 μm with an extra 5-10 μm separation for isolating two adjacent spots. Through both bench-top measurement and finite element simulation, we found the cross channel interference is below 10%. A customized software interface has been developed to control and program the stimulator operation.

Neurophotonics: a comprehensive review, current challenges and future trends

“…With this method, retinal ganglion cells expressing ChR2-eYFP were stimulated in vivo with a temporal precision in the millisecond timescale, with high cellular resolution through parallel multi-point stimulation delivered by the complex pattern. Another approach presents a patterned stimulation strategy based on high-power LEDs, where each frame can display flexible stimulation patterns (Cai et al, 2014). The 1,024 channels optical stimulation platform offers the possibility to manipulate the light delivery angle in each individual LED, producing flexible stimulation patterns refreshed at above 20 Hz.…”