Microfluidic Probes for Targeted Drug Delivery
Drug-delivery probes put a fluidic channel and 16 sites on one shank: a compound is infused and its effect recorded at one place. Designs and constraints.
4 min read
Updated September 23, 2026
A stainless-steel fluidic channel runs alongside the electrode array on the same shank, so a compound is infused and its effect recorded at the same place on one insertion. That co-location is the point: it is what lets you attribute a change in firing to the compound rather than to a second penetration somewhere nearby. The family is explained once in Drug-Delivery Series.
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#
Three catalog probe designs, all 16 sites on a single shank, on 15 µm silicon with 177 µm² iridium sites:
| design | shank length | site pitch |
|---|---|---|
| E16-10mm-25 | 10 mm | 25 µm |
| E16-10mm-50 | 10 mm | 50 µm |
| E16-20mm-100 | 20 mm | 100 µm |
Delivery packages are D16, DM16 and EIB64, at 16 and 64 channels. Channel termination options — at the tip, at a standard 90° angle, or at chosen positions along the array — and the Luer fitting are catalog data.
⚠ Fluidic channel dimensions are not in the product records. The inner and outer diameters quoted elsewhere come from the printed catalogs, which have been wrong before. Confirm them with an application scientist before designing an infusion protocol around a volume.
The constraint that decides the experiment#
Infusate volume displaces tissue, and the displaced tissue is the tissue you are recording. Rate and volume are therefore experimental variables rather than settings: infuse too fast or too much and the mechanical effect arrives before the pharmacological one, on the same electrodes, and the two are not separable afterwards.
Plan the rate against the structure's size, record a baseline long enough to see the mechanical transient resolve, and treat the first minutes after infusion as suspect unless you have shown otherwise.
Site pitch sets what you can resolve about spread. The 25 µm design samples a compact volume densely; the 100 µm design on a 20 mm shank trades that for reach. If the question is how far the effect travels, pitch is the specification that answers it.
Which experiments a drug-delivery probe is for#
The design exists for one question: what does this compound do to these neurons? Pharmacology in a behaving or anaesthetised animal has always had a spatial problem — an infusion cannula and a recording electrode are two objects in two places, and a change in firing after infusion can be the drug, the volume, or the distance between them. Putting the channel and the sixteen sites on one shank removes the distance: the recorded neurons are the infused neurons, and the effect is measured where it is applied, with a baseline from the same sites minutes before. That makes the probe the choice for local receptor pharmacology, for testing a compound's effect on a circuit before a systemic study, for delivering a viral vector or tracer at a recorded site, and for sampling as well as delivery where the channel is used to draw fluid.
It is not a general-purpose recording probe. The channel adds cross-section to the shank, the site count is fixed at 16, and the three designs are single-shank; a study whose primary need is coverage or unit yield uses a standard design and a separate cannula, accepting the distance.
How a drug-delivery probe is ordered and used#
The probe is one of the three catalog designs — E16-10mm-25, E16-10mm-50 or E16-20mm-100 — on a drug-delivery package: D16 and DM16 at 16 channels, with an optrode build (OD16LP) that adds a fibre for optical stimulation on the same trajectory. Every design has 177 µm² iridium sites on a 15 µm silicon substrate, so impedance, noise and stimulation behave as on any A-Series probe, and the setup and cleaning procedure is the same with one addition: flush the channel with sterile saline before and after every session, because a dried channel is a blocked channel. Choose the design by pitch — 25 µm to resolve the spread of an effect across a compact volume, 100 µm on the 20 mm shank for reach — and confirm the channel dimensions, the termination position and the Luer fitting on the quotation, since the fluidic specification is not in the product record. The package decision is in Choosing a Probe Package.