5 min read
Updated September 9, 2025
A silicon shank long enough to reach a deep target in a large brain is too slender to get there straight. The Vector Array™ solves that by carrying a short silicon electrode array on a rigid stainless-steel support body. The silicon does the recording; the steel does the travelling.
Research use only. NeuroNexus products and the procedures described here are for non-clinical research use, and must not be used in human or veterinary medical procedures.
The hybrid design, and why it matters#
A conventional silicon probe deflects under axial load once its length exceeds a few millimetres. Deflection is not just a targeting error. It is an unmeasured targeting error, because the tip does not go where the stereotaxic coordinates say it went.
The Vector Array separates the two jobs. The support body resists buckling over the full trajectory. The silicon array sits at the working end, spanning the depth you intend to sample. The rest of the shank is structure, not electrode.
Two consequences for experimental design:
- Recording span is fixed and short relative to the trajectory. Position the array on the structure; you cannot profile the whole track.
- The support body sets the tract diameter, and it is wider than a silicon shank. Plan the approach so the tract avoids ventricles and vessels along its whole length, not only at the tip.
Targeting#
Verify the trajectory, not just the coordinates. Angular error scales with depth. An error that is invisible at 2 mm places the array outside a small nucleus at 15 mm, which is the deepest Vector shank. Use imaging where the model allows it, and confirm the track histologically afterwards.
Insert slowly and monitor as you go. Advancing under recording gives you the tissue's own landmarks: white matter silence, and the firing signatures of intervening nuclei. It is the only in-session check on depth you have.
Account for brain shift. Opening the dura and losing CSF moves deep structures. In large-brain models the shift is on the order of the structures you are targeting.
Configurations#
Vector Arrays are made in several forms, and the choice is set by the experiment rather than by channel count alone:
- Acute — repeated use across sessions, with cleaning between.
- Chronic — packaged for fixation and long-term cable management, in implantable lengths sized to the headcap and the mounting hardware.
- High-density variants — closer site spacing over a shorter span, for fine structure.
- Optical variants — an optical fibre bonded alongside the array for combined optogenetic stimulation and recording. Fibre core diameter and numerical aperture trade irradiance at the target against the size of the tract, and that trade is the selection criterion.
The shape of the catalog#
Four site layouts are offered, and the layout constrains the site count, the array length and the site pitch available to you. Measured across the 16 catalog Vector Array designs:
| Layout | Designs | Recording sites | Array length | Site pitch | Site area |
|---|---|---|---|---|---|
| Edge | 10 | 16 / 32 / 64 | 10, 12, 15 mm | 50-200 µm | 177 µm² |
| Poly2 | 3 | 16 / 32 / 64 | 10 mm | 50 µm | 177 µm² |
| Poly3 | 1 | 64 | 10 mm | 25 µm | 177 µm² |
| Tetrode | 2 | 16 / 32 | 15 mm | 300 µm (cluster pitch) | 121 µm² |
Every catalog Vector Array is single-shank with iridium sites on a silicon substrate. Read the table for the shape of the decision, not as an order form: site areas, support-body diameters and implantable lengths are per-design catalog data. Confirm the configuration against your mounting hardware before ordering.
Working with drives and chambers#
Vector Arrays are used with chronic primate microdrives and with third-party drives, and the drive usually decides the mechanical envelope. Check three things before ordering:
| Check | Why it bites | Confirm against |
|---|---|---|
| Does the drive grip the support body diameter you are ordering | The support body is wider than a silicon shank, and drive collets are sized for wire and for bare silicon | Drive vendor's collet specification, and the ordered support-body diameter |
| Does the assembled stack clear the chamber at the intended angle | Clearance is worst at the steepest approach angle, which is usually the one the anatomy forces on you | Chamber inner diameter and the connector-to-tip stack height |
| How far does the drive travel | Travel has to cover the depth uncertainty, not the depth | Stereotaxic depth error for your model, plus expected brain shift |
A drive that advances the array is also the answer to a lost unit in chronic work. Plan a travel budget at implant rather than after the first quiet week.
Reuse and care#
Acute Vector Arrays are built for repeated use. Lifetime depends on handling, not on a rated cycle count. Clean promptly after each session, never wipe the array face, and inspect the silicon under magnification before each surgery. Impedance measured across sessions is the earliest indicator that a site is failing.
Research applications#
- Basal ganglia and thalamus in large-brain models, where depth puts the target beyond a standard laminar probe.
- Brainstem nuclei, where the tract is long and the structures are small.
- Chronic behavioural work in non-human primates, recording during task performance across sessions.
- Combined optogenetics and recording at depth, using the optical variants.