Plexon U-Probe

U-Probes* are exceptionally customizable and robust, multi-use, multi-site linear electrodes most often used for acute recordings in medium to large animals.

neural probes - u probe

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 40 µm diameter options. The small electrode site diameter (15 µm) 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, 32, or 64* channels.

neural probe channel configuration

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

fluid channel and optic fiber configuration - neural probes

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, these neural 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, neural probes and arrays including our V-Probes and Thumbtack Probe the latter one for chronic use.

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.

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

Neural probes can be purchased independently or operated in conjunction with the OmniPlex® Neural Data Acquisition System. Your Plexon Sales Engineer is happy to provide additional information and to assist you in determining what might be the most advantageous neural probe configuration.

*64 Channel neural probes are available in single and stereotrode configuration. 64 Channel probes with a single electrode configuration are available with 50, 75, or 100um inter-electrode spacing. 64 channel probes with stereotrode configuration require 100 µm or 150 µm interelectrode spacing.

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 neural 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, 32, or 64
Total probe length30 to 150mmLength is customizable within range provided; however, the most typical request is 100mm. Total neural 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 360 μmNeural probe 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 640 μmNeural probe diameters of 236 μm and greater require a 640 μm reinforcement tube
Electrode construction15 μm 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 spacing50 μm, 75 μm, 100 μm, 150 μm, or 200 μm along length of probe;
50 μm within stereotrode or tetrode group
64 Channel neural probes are available in single and stereotrode configuration. 64 Channel probes with a single electrode configuration are available with 50, 75, or 100um inter-electrode spacing. 64 channel probes with stereotrode configuration require 100um or 150um interelectrode spacing.
Distance from tip to the closest electrode site
Dependent on neural probe diameter (See table below):
185 probe diameter: 320 μm
210 probe diameter: 360 μm
236 probe diameter: 410 μm
260 probe diameter: 450 μm
300 probe diameter: 520 μm
320 probe diameter: 560 μm
360 probe diameter: 620 μm
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 accommodate 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 accommodate 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.

64 channel neural probes are able to accommodate 1 fluid capillary/optic fiber.

Fluid capillary ID40 μmFluid capillaries are slightly offset from the center line of the electrodes.
Fluid capillary OD60 μm
Optic fiber OD50 μmOptic 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
64 channel: 2x CON/32-mV or CON/64f-Samtec
Omnetics and Samtec 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
640320560640
641360620640

^Batch variation in tubing inner diameter may require a larger neural 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
64**0320560640
64**1360620640

*U-Probes are manufactured by Neuronelektród.

**Available in Stereotrode configuration with interelectrode spacing of 100um or 150um

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

Our linear probes are extremely customizable, some of our most popular custom options include:

Rotated connector:

Rotating the connector 90 degrees allows for the headstage to be plugged in from the top which can alleviate spacing issues.

Kinked/Angled Reinforcement Tube:

Probes can be made with a “kink” in the reinforcement tube. Customers specify the angle and the location of this bend. Changing the angle of the reinforcement tube can make it easier to plug in the headstage when recording from brain regions close together.

Fluid Channels:

Up to 4 fluid delivery channels for precise drug delivery can be added to S, U, and V-Probes. The placement of these fluid channels depends on the type of probe chosen. A connector steel tube (360um OD) is pulled over the fluid capillary (60um OD) and polyethylene or silicone tubing can be used to connect to the injection system.

Fiber Optics:

Up to 4 fiber optic lines for optogenetic stimulation can be added to S, U, and V-Probes and intermixed within the recording sites. The placement of these fiber optics depends on the type of probe chosen. Probes will be manufactured with a LC ferrule that can be used to connect to your light source.

Jumper Location:

You can have the location where the jumper cables connect moved to better fit your experimental designs. For example, jumpers can me moved so that they are accesible from the side.

“Pig-Tail” Connector Design:

The unique pig-tail connector design allows for greater flexibility with site orientation and easier movement of the probe while in the microdrive. The length of the cable between the reinforcement tube and the connector can be customized.