A-Series Probes (Polytrode & Tetrode)
Hardware
A polytrode or tetrode silicon probe has closely spaced sets of sites arranged in several columns or in clusters of four along the shank, so a neuron is recorded on several sites at once for single-unit isolation and current-source density analysis.
Polytrode designs place sites in columns along the shank, so the dense sampling still covers depth. Tetrode designs group sites in fours at intervals along the shank, giving isolation at each cluster and no sites between them. Catalog designs have 16 to 256 sites on 1 to 9 shanks, 3 to 10 mm long, with sites usually 177 µm² and 160 and 121 µm² options, at a within-cluster pitch of about 20 to 25 µm; iridium is the standard site metal, with Z-coat (PEDOT) as an option. The Q-Trode series is the single-tetrode version; spike sorting and current-source density are the analyses the layouts serve.
Records and stimulates. Research use only.
Typical values
| Catalog designs | 39 |
|---|---|
| Sites | 16 to 256 |
| Shanks | 1 to 9 |
| Shank length | 3 to 10 mm |
| Site area | 97 to 220 µm² |
| Cluster pitch | about 20 to 25 µm |