Tungsten Bipolar Electrodes, Standard Tip

(MicroProbes)

Description

Tungsten is a versatile and widely-used microelectrode material that offers a good balance between performance and cost.

Advantages

Disadvantages

Extremely strong and stiff metal provides probes with exceptional rigidity.
Great for acute and chronic recording due to biocompatibility and lower cost.
High corrosion resistance offers consistent long-term performance.

Does not provide the same degree of electrochemical performance or stability as platinum-iridium alloy, making it a poor alternative for microstimulation.
Lower charge transfer capacity of tungsten will result in larger, potentially unsafe interfacial potentials when applying the same stimulation current as to a platinum-iridium electrode.
Certain pH or stimulation conditions can lead to tungsten corrosion.

These bipolar microelectrodes of MicroProbes are also available in Platinum-Iridium and Elgiloy (an alloy similar to stainless steel). Each electrode is etched to a fine taper and tipped using a proprietary process to a specific impedance value. We offer a variety of different tip alternatives for those that prefer a specialized electrode profile for their research. There are four different tip profiles are also available to further fine-tune your electrode selection to your particular application. The tip selection can provide subtle yet important changes to the performance of the electrode, as described below. It is recommended that first time users consider experimenting with different tip profiles to determine which works best for their recording or stimulation protocols.

Stereotrodes are excellent for bipolar stimulation studies where the current injection needs to be confined to a small localized part of the neural tissue. They have also been used for enhanced isolation of single neural elements by simultaneous recordings of multiple units on two closely spaced microelectrodes. The tip spacing is typically equal to the diameter of the electrode shaft, however, they can be specified to greater separations in most instances.

As an alternative you may consider choosing monopolar electrodes with a thin Paryclene-C coating or with Polymide tubing for insulation, or concentric electrodes.

Stereotrodes (Bipolar Electrodes), Tungsten, Standard Tip
(75 µm × 3")

Item	Length	Outside Diameter	Tip Separation	Impedance	Applications	Pkg of 10
WE3ST30.1A3	76 mm	0.216 mm	75 µm	0.1 MΩ	Multi Unit record. & Stim.
WE3ST30.5A3	76 mm	0.216 mm	75 µm	0.5 MΩ	Single & multiunit rec. & stim.
WE3ST31.0A3	76 mm	0.216 mm	75 µm	1.0 MΩ	Single & multiunit rec. & stim.
WE3ST31.5A3	76 mm	0.216 mm	75 µm	1.5 MΩ	Single & multiunit rec. & stim.
WE3ST32.0A3	76 mm	0.216 mm	75 µm	2.0 MΩ	Greater Selectivity & Micro. Stim.

Stereotrodes - Tungsten - Standard Tip
(125 µm × 3")

Item	Length	Outside Diameter	Tip Separation	Impedance	Applications	Pkg of 10
WE3ST30.1A5	76 mm	0.356 mm	125 µm	0.1 MΩ	Multi Unit record. & Stim.
WE3ST30.5A5	76 mm	0.356 mm	125 µm	0.5 MΩ	Single & multiunit rec. & stim.
WE3ST31.0A5	76 mm	0.356 mm	125 µm	1.0 MΩ	Single & multiunit rec. & stim.
WE3ST31.5A5	76 mm	0.356 mm	125 µm	1.5 MΩ	Single & multiunit rec. & stim.
WE3ST32.0A5	76 mm	0.356 mm	125 µm	2.0 MΩ	Greater Selectivity & Micro. Stim.

Stereotrodes - Tungsten - Standard Tip
(125 µm × 5")

Item	Length	Outside Diameter	Tip Separation	Impedance	Applications	Pkg of 10
WE5ST30.1A5	127 mm	0.356 mm	125 µm	0.1 MΩ	Multi Unit record. & Stim.
WE5ST30.5A5	127 mm	0.356 mm	125 µm	0.5 MΩ	Single & multiunit rec. & stim.
WE5ST31.0A5	127 mm	0.356 mm	125 µm	1.0 MΩ	Single & multiunit rec. & stim.
WE5ST31.5A5	127 mm	0.356 mm	125 µm	1.5 MΩ	Single & multiunit rec. & stim.
WE5ST32.0A5	127 mm	0.356 mm	125 µm	2.0 MΩ	Greater Selectivity & Micro. Stim.

Stereotrodes - Tungsten - Standard Tip
(250 µm × 3")

Item	Length	Outside Diameter	Tip Separation	Impedance	Applications	Pkg of 10
WE3ST30.1A10	76 mm	0.610 mm	250 µm	0.1 MΩ	Multi Unit record. & Stim.
WE3ST30.5A10	76 mm	0.610 mm	250 µm	0.5 MΩ	Single & multiunit rec. & stim.
WE3ST31.0A10	76 mm	0.610 mm	250 µm	1.0 MΩ	Single & multiunit rec. & stim.
WE3ST31.5A10	76 mm	0.610 mm	250 µm	1.5 MΩ	Single & multiunit rec. & stim.
WE3ST32.0A10	76 mm	0.610 mm	250 µm	2.0 MΩ	Greater Selectivity & Micro. Stim.

Stereotrodes - Tungsten - Standard Tip
(250 µm × 5")

Item	Length	Outside Diameter	Tip Separation	Impedance	Applications	Pkg of 10
WE5ST30.1A10	127 mm	0.610 mm	250 µm	0.1 MΩ	Multi Unit record. & Stim.
WE5ST30.5A10	127 mm	0.610 mm	250 µm	0.5 MΩ	Single & multiunit rec. & stim.
WE5ST31.0A10	127 mm	0.610 mm	250 µm	1.0 MΩ	Single & multiunit rec. & stim.
WE5ST31.5A10	127 mm	0.610 mm	250 µm	1.5 MΩ	Single & multiunit rec. & stim.
WE5ST32.0A10	127 mm	0.610 mm	250 µm	2.0 MΩ	Greater Selectivity & Micro. Stim.

Common Tip Profiles:

Schematic of Standard Tip — **A - STANDARD TIP PROFILE**
The standard tip profile features a sharp yet robust point that offers versatile performance and an effective balance between penetration and durability.

Schematic of Blunted Tip — **B - BLUNTED TIP PROFILE**
The blunted electrodes are engineered to have a more rounded, bullet-shaped tip. For many applications the blunted tip can offer superior stimulation performance.

Schematic of Heat Treated Tapered Tip — **H - HEAT TREATED TAPERED TIP PROFILE**
The heat-treated electrodes are intended for those investigators who must penetrate their probes through tough membranes, such as the dura mater of larger mammals.

Schematic of Extra Fine Tip — **F - EXTRA FINE TIP PROFILE**
The extra-fine tip profile features a significantly sharper taper as well as a thinner insulation layer.

Also see:

Selecting the Optimum Electrode Configuration