Fully Implantable 192x256 SPAD Sensor with Global-Shutter and Micro-LEDs for Bidirectional Subdural Optical Brain-Computer Interfaces

We demonstrate a fully implantable optoelectronic neural interface device featuring an array of single-photon avalanche photodiode (SPAD) detectors with a global shutter and monolithically integrated with an array of flip-chip bonded micro-LEDs (REED) for fluorescence excitation and optogenetic stimulation. The device is integrated with optical filters and a lensless computation mask to create a 200-mu m-thick implantable device. To enable the global shutter, an area-efficient 10b roll-over counter is used in-pixel. With a phase unwrapping algorithm, these counters can be used in a "modulo" fashion providing high dynamic range extension. Our SPAD sensor architecture achieves a better noise . power figure-of-merit (FoM) than comparable photodiode image sensors.