A 512-Pixel, 51-kHz-Frame-Rate, Dual-Shank, Lens-Less, Filter-Less Single-Photon Avalanche Diode CMOS Neural Imaging Probe

We present an implantable single-photon shank-based imager, monolithically integrated onto a single CMOS IC. The imager comprises of 512 single-photon avalanche diodes distributed along two shanks, with a 6-bit depth in-pixel memory and an on-chip digital-to-time converter. To scale down the system to a minimally invasive form factor, we substitute optical filtering and focusing elements with a time-gated, angle-sensitive detection system. The imager computationally reconstructs the position of fluorescent sources within a 3-D volume of 3.4 mm $\times $ 600 $\mathrm {\mu }\text{m}\,\,\times $ 400 $\mu \text{m}$ .