Site Count
Site count is the number of electrode sites on one design — the channels it can record or stimulate on at once.
On a silicon probe it is the product of shanks and sites per shank; on a thin-film grid it is the number of contacts on the film. It is the first field of a probe name — the 32 in A1x32-5mm-100-177 — and the number a package and headstage are matched to.
Count sets coverage, not quality. More sites reach more neurons only when the layout places them in new tissue; more sites in the same tissue give more views of the same neurons, which is what a tetrode or high-density layout is for. So the count is read with pitch and span: 32 sites at 100 µm profile 3 mm of depth, and 32 sites at 25 µm resolve units in 0.8 mm. The count also fixes what the probe can be used with — a 16- or 32-site design mates to a 16- or 32-channel connector and headstage, a 256-site design needs a high-density package — and it scales the data volume of every session. Each site itself is under electrode site.
Typical values
| Catalog silicon probes | 4 to 1,024 sites; 32 is the median |
|---|---|
| Catalog thin-film grids | 3 to 256 sites; 32 is the median |
| Design-space parameter | Site count (numSites) |