Active-Pixel Probe

The pixel is the unit: one electrode site and the CMOS circuit beneath it that amplifies, filters and multiplexes its signal before it leaves the probe.

A passive silicon probe carries one metal trace from each site to the connector, and a headstage off the probe amplifies and digitizes the analog signals; its site count is bounded by the traces a shank can carry. An active-pixel probe moves that electronics onto the shank, which is what makes 1,024 sites on a 5 mm shank tractable: the cable carries data, not a thousand analog lines. Neuropixels probes take the same approach with the circuitry at the probe base (Jun et al. (2017)); SiNAPS puts the pixel under the site itself (Angotzi et al. (2019)). What the active design gives up is flexibility: sampling is fixed by the chip, and there is no stimulation path through a pixel array, so active-pixel probes record only.

NeuroNexus offers active-pixel probes as the HD Series SiNAPS designs, 256 to 1,024 sites on one to eight shanks with 196 µm² platinum sites at 29 µm pitch, digitized at 12 bits and 20 kS/s per pixel, in the Activus SiNAPS package with no headstage. The passive catalog covers recording and stimulation; the DAQ chip entry places the two architectures beside the Intan headstage chips. Research use only.