Optoelectrodes: Silicon Probes for Optogenetics
Optoelectrodes integrate an optical fiber with the sites on one shank, so the neurons recorded are those stimulated. Builds, constraints, experiments, ordering.
5 min read
Updated October 12, 2026
One or more optical fibers are integrated with the recording sites on a single shank, so light is delivered and its effect recorded at the same place. That is what lets you claim the neurons you recorded are the neurons you stimulated — a claim a separate fiber and probe cannot support. The family is explained once in Optoelectrode Package ↗.
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.
What the catalog contains#
Twenty-nine catalog optoelectrode packages across nine package families. Each is a build of its base family rather than a family of its own:
| line | channels | notes |
|---|---|---|
Optoelectrode builds of the A-Series, CM, Hybrid, ZIF and Drug Delivery packages (pkg_acl, pkg_cmm, pkg_hyb, pkg_zif, pkg_drd) | 16, 32, 64, 128 | low-profile (LP) and chronic (OZ, OHZ) forms; every optoelectrode is tagged pkgseries:o |
Optoelectrode/Vector (pkg_vec) | 16, 32 | 70 and 110 mm cable options |
Optoelectrode/Q-Trode (pkg_qtr) | 4 | |
Optoelectrode/AVS build of Activus SiNAPS (pkg_avs) | 256, 1,024 | SiNAPS probes with a fiber |
Catalog record names evidence a 50 µm-core fiber and cable lengths of 60 and 100 mm.
⚠ Fiber specifications are not in the product records. No record in the catalog carries a core diameter, cladding diameter or numerical aperture field. An earlier version of this document listed eight core/cladding/NA combinations; none of them could be traced to a source, so they have been removed. Confirm the fiber configuration with an application scientist before ordering, and treat any fiber figure not on a quotation as unverified.
The constraint that decides the experiment#
Light and tissue are the variables, not the probe. Irradiance falls steeply with distance from the fiber tip, so which neurons are illuminated is set by the fiber's position relative to the sites and by the tissue's scattering — not by the power you set at the source. Two consequences:
- Sites near the fiber see a different stimulus from sites far from it. That gradient is across your own array, so it is part of every result and worth mapping before it is interpreted.
- Photoelectric artifact lands on the recording you are trying to read. It is an electrode response to light, not neural activity, and it scales with irradiance. Expect it, measure it in a non-expressing control, and design the pulse so it is separable in time from the response.
Fiber choice is a package decision made before ordering, because the fiber is integrated on the shank rather than positioned at surgery.
Which experiments an optoelectrode is for#
An optoelectrode is chosen when the claim is causal: that the neurons whose activity was recorded are the neurons whose activity was manipulated. Optogenetic tagging — identifying a recorded unit as a member of a genetically defined population by its short-latency response to light — needs the light and the site within a detection radius of each other, which is what a fiber integrated on the shank guarantees and a separately placed fiber does not. The same geometry serves closed-loop stimulation, where a recorded event triggers light at the recorded place, and circuit dissection, where a population is silenced and the effect on its neighbors read on the same array. The optoelectrode builds on the Q-Trode ↗ put the fiber at a single tetrode cluster, so the tagged cells are the separable ones; the Vector optoelectrode builds bring light to a deep target in a large animal on the same 70 or 110 mm trajectory as the array.
It is not the choice when the light and the recording are naturally separate — a wide-field manipulation read from a distant structure — because the fiber adds cross-section along the whole trajectory and a photoelectric artifact at every pulse, and a separate fiber costs nothing in that case.
How an optoelectrode is ordered and used#
The optoelectrode is a package build, not a probe: choose the design against the target first, then the package series the preparation needs, then its optoelectrode form — OA32LP on the A-Series, OCM16LP on CM for a chronic mouse, OH32LP on the Hybrid series, OV32 on Vector, OD16LP on drug delivery, the Optoelectrode/AVS build on SiNAPS. The fiber terminates in a standard fiber-optic connector for a separate laser or LED source, and the fiber configuration — core, cladding, numerical aperture, length — is confirmed on the quotation because it is not in the product record. Before the first session, record the photoelectric artifact in saline and in a non-expressing control at the irradiance you will use, so that the pulse can be designed to keep the artifact separable in time from the response; then treat the irradiance gradient across the array as part of the result. The package decision is in Choosing a Probe Package; the design in Choosing an Electrode for Your Experiment.