Pneumatically-actuated Impulse Microelectrode Array Inserter

Key Features

• Enables the insertion of high-density microelectrode arrays into neural tissues.
• Adjustible insertion depths, typically 0.5, 1.0 or 1.5 mm.
• Insertion temime less than 1 ms to insure complete implantation.
• Sterilizable insertion wand and electrical trigger.

General Description

The Cyberkinetics Microelectrode Array Inserter is a pneumatically-actuated system that permits the complete insertion of high density microelectrode arrays into cerebral cortical tissues with minimal tissue insult.

The very large surface area of the set of penetrating needles that make up the Cyberkinetics Microelectrode Array permits excellent, long term recording stability, but the high density of electrodes makes it difficult to implant them in neural tissues in a conventional manner. Trying to push the array into the tissues only mechanically depresses the surface of the tissue, resulting in incomplete insertion of the array and potential tissue trauma. However, the viscoelastic nature of neural tissues makes it possible to insert the array with a high velocity implantation technique. Our pneumatically-actuated inserter has been designed to use a momentum impulse technique to insert the 1.5-mm long 100-electrode arrays into feline and primate cerebral cortical tissues in about 3 ms.

The insertion system is composed of three components:

1. An insertion 'wand', about the size of a pencil, that implants the electrode array using a captive tip.
2. A control module containing a compressor/vacuum pump, valving, and electronics that is connected to the wand by flexible tubing.
3. A remote trigger that electrically actuates the control module and initiates array insertion. As a safeguard, the trigger is inoperative until the control module is armed.

The implantation procedure is as follows: The array is placed with its electrode tips resting on the tissue. The wand is positioned over the array with its tip just touching the back of the array and coaxially oriented with the electrodes. The precise location of the wand is achieved using standard clamping or stereotaxic systems.

When the wand is in position and the control module is armed, the trigger is depressed. A small piston inside the wand is accelerated pneumatically and impacts the tip, imparting a predetermined momentum which in turn is transferred to the array achieving implantation in the tissue. The travel of the captive tip is adjustable so that the electrodes are inserted to the correct depth. The momentum transferred to the array is also adjustable. Both the wand and the trigger can be sterilized with ethylene oxide or, in the case of the wand, by autoclaving.

The impulse inserter is housed in a portable attachÈ case that also contains the wand, trigger, control module and power cord for convenient storage.

This high velocity insertion technique has been used in scores of array implantations and produces complete array insertions with little bleeding and minimal tissue insult. The inserter has a number of variable parameters which allow the user to implant Cyberkinetics Electrode Arrays into a wide variety of neural tissues.

Specifications

Control Module

Pressure range: 0 to 30 PSI.
Controls: Insertion pressure, power, run/fill, trigger enable, trigger.
Inserter: 12" x 12" x 5"; carrying case: 18" x 13" x 5".
Weight: 16 lb.; Complete system in case = 22 lb.
Power: 110 VAC, 2 amp or 220 VAC, 1 amp

Wand

Length: 10.5"
Diameter: 5/16"
Weight: 2.5 oz.

Trigger

Dimensions: 3" long x 0.75" diameter
Cable: 6' long.

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