High-Yield Passive Si Photodiode Array Towards Optical Neural Recording

Emerging fluorescent protein-based sensors allow researchers to monitor neural activities via optical recording of the fluorescence signals. This optical method is able to monitor multiple cell signals with ease in identifying individual cells in dense neurocircuitry. To this end, we demonstrate a high-yield passive Si photodiode array, aiming to establish a miniaturized optical recording device toward in-vivo use. Our fabricated array features a high yield ( >90%), low detection limit (32 μW/cm
²
), and high speed (1000 frames per second for scanning up to 100 pixels). Using a fast I-V measurement setup, we examined the device performance in terms of detection limit and speed. A mapping of the light intensity on the entire array manifests its promise as an on-chip fluorescence imager for optical neural recording. The array routinely consumes sub-10μW power, which is suitable for chronic in vivo use.