Plexon U-Probe

U-Probes* are Plexon’s most popular and fastest growing product in the electrodes, probes and arrays category.  They are exceptionally customizable and robust, multi-use, multi-site linear electrodes most often used for acute recordings in medium to large animals.

Flexibility in the manufacturing process allows for different electrode site arrangements and spacing, as well as optional fluid delivery channels for precise drug delivery or fiber optic lines for optogenetic stimulation intermixed within the recording sites. The precise linear arrangement of the electrode sites enables current source density analysis of the field potential signals as recorded from laminar neural structures.

The platinum/iridium electrode recording sites are available in 15, 20, 25 and 40µm diameter options. The small electrode site diameter (15µm) enables effective single-unit recording, while a unique etching process of the electrode surface results in lowered impedances without significantly changing the overall surface area of the exposed recording site. The result is a small site suitable for resolving single units coupled with low impedance for a better signal-to-noise ratio.

U-Probes are conveniently available in single, stereotrode and tetrode configurations, each with a choice of 8, 16, 24, or 32 channels.

Below are all three 16 channel configurations illustrated with four fluid capillaries or optic fibers:

U-Probes are well known for their robustness due in part to their stainless steel construction (as opposed to silicon), and ability to penetrate deep within the brain. When used according to proper procedures, U-Probes will support many penetrations over a long period of time.

You may also wish to explore other options in Plexon’s family of specialty electrodes, probes and arrays including our V-Probes and Thumbtack Probe the latter one for chronic use.

U-Probes are Plexon’s most popular and fastest growing product in the electrodes, probes and arrays category. U-Probes are expertly handcrafted and made to order with many finished options available. As a result, please expect a six week manufacturing lead time for standard specifications. Some specifications or configurations, such as tetrodes, can take an additional two to three weeks. Your Plexon Sales Engineer is happy to provide additional information and to assist you in determining what might be the most advantageous U-Probe configuration.

See the illustration under the Technical Specs tab to view the anatomy of a standard U-Probe by front and top (connector) view.

The illustration below depicts the anatomy of a standard U-Probe by front and top (connector) view. The 8 channel, single electrode configuration is featured as the example (see page 8 of the U-Probe Technical Guide located in the Resources tab for more details on this particular channel count). Electrode sites are numbered from connector to tip.

U-Probes are customizable, as can be seen from the table below. It may also be possible to produce probes beyond the specifications below. As a result, it is recommended that you discuss your needs with a Plexon Sales Engineer to determine the best configuration and if your unique request can be accommodated.

FeatureSpecifications and OptionsRemarks
ApplicationIn vivo; acute
Channel counts8, 16 24, or 32
Total probe length30 to 150mmLength is customizable within range provided; however, the most typical request is 100mm. Total probe length is measured from tip to the connector. The difference between the total probe length and the reinforcement tube length is a minimum of 25mm.
Probe OD185 to 360μmProbe diameters vary based on the number of electrodes, fluid channels and optic fibers. See the U-Probe diameter tables found in the U-Probe Technical Guide under Technical Specifications.
Reinforcement tube length5 to 125mmLength is customizable within range provided
Reinforcement tube outer diameters460 or 640μmProbe diameters of 236μm and greater require a 640μm reinforcement tube
Electrode construction15μm Pt/Ir electrode site diameter, circular shape, HML insulated (polyimide), and secured in medical-grade epoxy
Electrode configurationsSingle, stereotrode or tetrodeSingle configuration is most typical; stereotrodes and tetrodes tend to be used in areas with an especially high density of neurons (i.e. hippocampus).
Inter-electrode spacing50μm, 75μm, 100μm, 150μm, or 200μm along length of probe;
50μm within stereotrode or tetrode group
Distance from tip to the closest electrode site
Dependant on probe diameter (See table below):
185 probe diameter: 320μm
210 probe diameter: 360μm
236 probe diameter: 410μm
260 probe diameter: 450μm
300 probe diameter: 520μm
320 probe diameter: 560μm
360 probe diameter: 620μm
The numbering of the electrode sites is such that channel #1 is closest to the connector. Conversely, the electrode site closest to the tip is the largest channel # on the probe.
Stimulation optionsSingle: Up to four fluid capillaries and/or optic fibers

Stereotrode or Tetrode: Up to two fluid capillaries and optic fibers

Single: Able to accomodate any combination of up to four additional fluid capillaries/optic fibers. Examples: four fluid capillaries; or four optic fibers; or one fluid capillary with three optic fibers. The total count of fluid capillaries plus optic fibers may not exceed four.

Stereotrode or Tetrode: Able to accomodate any combination of up to two additional fluid capillaries/optic fibers. The same examples that apply for the single configuration above apply here, however, the total count of fluid capillaries plus optic fibers may not exceed two.

Fluid capillary ID40μmFluid capillaries are slightly offset from the center line of the electrodes.
Fluid capillary OD60μm
Optic fiber OD50μmOptic fibers are slightly offset from the center line of the electrodes.
Connector interfaces
8 channel: CON/8o50m-10P
16 channel: 2x CON/8o50m-10P, CON/16m-V or CON/16o25m-18P
24 channel: 3x CON/8o50 or CON/32m-V
32 channel: CON/32m-V
All are Omnetics connectors.
LifespanRobust and reusable with a minimum of thirty penetrations, likely many more

The two U-Probe diameter tables below provide the minimum diameters for all electrode, fluid capillary and optic fiber combinations.

Single Electrode Configuration:

ChannelsFluid Capillaries or Optic FibersMinimum Probe Diameter (μm)^Minimum distance from tip to 1st electrode (μm)Reinforcement tube diameter (μm)^
80, 1185320460 or 640
82210360460 or 640
83260450640
84300520640
160185320460 or 640
161210360460 or 640
162236410640
163300520640
164320560640
240210360460 or 640
241236410640
242
300
520640
243320560640
244360620640
320260450640
321260450640
322300520640
323320560640
324360620640

^Batch variation in wire inner diameter may require a larger probe diameter or larger reinforcement tube

Stereotrode/Tetrode Configurations:

ChannelsFluid Capillaries or Optic FibersMinimum Probe Diameter (μm)^Minimum distance from tip to 1st electrode (μm)Reinforcement tube diameter (μm)^
80-1185320460 or 640
82210360460 or 640
160185320460 or 640
161, 2236410640
240210360460 or 640
241,2260450640
320260450640
321,2300520640

*U-Probes are manufactured by Neuronelektród.

^Batch variation in wire inner diameter may require a larger probe diameter or larger reinforcement tube.

Guides and How To Papers

Technical Specs and Data Sheets