A Wireless Subdural Optical Cortical Interface Device with 768 Co-Packaged Micro-LEDs for Fluorescence Imaging and Optogenetic Stimulation

One of the goals of neuroengineering is to establish high-bandwidth, fully implantable, and minimally invasive wireless neural interfaces that help interrogate neural circuits in freely moving and socially behaving animals. Optical interfaces offer advantages over electrophysiological techniques such as cell-type specificity, low cross-talk bidirectionality, and wide field-of-view (FoV). While most optical interfaces to-date have taken the form of bulky “mini-scopes”, recent advances in optical interfaces have shown promise in achieving high-resolution, volume-efficient brain interfacing over large FoVs with devices accommodated entirely within the subdural space [1], [2]. These devices, however, still require wired connection through the skull, negating advantages of their volumetric efficiency. We introduce a fully wireless, 12x12 mm
²
subdural optical interface with a 5.76x7.68 mm
²
FoV for lens-less imaging and optogenetic stimulation. The FoV can span multiple brain regions in non-human primates, enabling brain coordination studies with unprecedented detail. The device features monolithically integrated single-photon avalanche diodes (SPADs) in a 192x256 array with a pitch of 30μm for fluorescence imaging, complemented by an integrated array of 24x32 micro-LEDs (μLEDs) with 240μm pitch for fluorescent excitation and optogenetic stimulation. A hybrid emission filter, an excitation filter, and a computational imaging mask complete the packaging stack-up as shown in Fig. 1. The CMOS die is thinned to approximately 15μm; the entire device is approximately 150μm thick and mechanically flexible to a radius of curvature of 12.5mm. On-chip antennas support wireless powering and bidirectional ultra-wide-band (UWB) radio link. The implant communicates with and is powered by a wearable “relay station” positioned directly outside the skull as shown in Fig. 1.