Chronic Array Assemblies

The challenge in designing a chronic array assembly is to minimize the footprint of the skull-mounted connector and to minimize the mating and un-mating forces of the connector and the plug on the external cable to the amplifier. We are now offering a variety of chronic microelectrode systems ranging from a 32-electrode connector system designed for small animals such as rats, to a high-end 96-electrode high-density connector system. We also have durable 96-electrode chronic assembly designed specifically for large animals, such as monkeys.

Coming Soon in Summer, 2007

Cyberkinetics iridium tip microelectrode array for chronic neural stimulation & recording - Cortical long term microstimulation has the potential to revolutionize the field of neuroprostheses. Electrical stimulation of various cortical regions has been employed for many years for purposes ranging from mapping of brain regions to manipulating behavioral decisions. Initial studies of surface electrical stimulation involved activating large regions of the brain in order to test perception in sensory areas and gross movement in motor regions. However, the field of intra-cortical microstimulation can provide an understanding of the underlying effects of forcing current into the brain beyond activating very large volumes of neurons surrounding the electrode site.

Key Features for All the Chronic Array Assemblies

• Up to 100 penetrating microelectrodes per array.
• Electrodes 1.0 or 1.5 mm in length with a 400 µm pitch
• Diameter of electrode at base is approximately 80 µm.
• Radius of electrode tip is approx. 3-5 µm.
• Active electrode region is platinum, approx. 35-75 µm long.
• Electrode impedance is approximately 100-800 kOhm.
• Substrate is 4.2 mm x 4.2 mm x 0.25 mm silicon (for the 100 electrode array).
• Applications in sensory cortex, visual cortex, motor cortex, spinal cord, association areas and peripheral nerve fibers.
• Primates, felines, rats.
• Exceptional recording stability
• Also capable of stimulating neurons.

Ordering information required

1. Length of electrodes: 1.0 mm or 1.5 mm.
2. The type of connector you want (see below).
3. Total number of electrodes in the array: e.g. 10x10, 6x6, 5x5. (Multiple electrode arrays are also possible.)
4. Length of wire bundle between array and chronic connector.(We recommend adding about 15% to the geometric distance between the implant site and the connector position so you can incorporate a curve in the wire bundle to act as a stress relief as the brain moves with respect to the skull.)

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CerePort™: 96-Electrode Chronic Microelectrode Array Assembly

The CerePort™ is a 96-pin chronic high-density percutaneous connector system designed for a wide range of experiments.

Electrodes:

• 100 electrodes per array (or custom).
• 96 Active electrodes

Lead Wires:

• 96 insulated, 1.0-mil Au/Pd wire bonded to 96 electrodes.
• Lead wire length can be from 2 cm to 13cm.
• Lead wires are bonded to bond pads on the rear surface of the array and potted with medical grade silicone elastomer.

Percutaneous Connectors:

• Twin connectors, each comprising a 38-lead edge connector mounted in a titanium pedestal (19 mm dia base, 11 mm dia body, 4.5 g).
• Lead wires potted in base of pedestal with silicone elastomer.

The pedestal was designed for long-term implantation. The low-profile design allows for protection from damage during and after experimental recordings. A protective cap provides protection from animal interference and prevents body fluids from entering the connector. The CerePort™ plug is fitted on the animal during experiments and recording sessions with zero insertion force.

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MultiPort™: 96-Electrode Chronic Microelectrode Array Assembly

The MultiPort™ is a 96-pin chronic high-density percutaneous connector system designed for a wide range of experiments that require multiple arrays to implant in different cortical areas with the convenience of a single connector.

Electrodes:

• Up to 4 microelectrode arrays per connector.
• Up to 96 Active electrodes

Lead Wires:

• 96 insulated, 1.0-mil Au/Pd wire bonded to 96 electrodes.
• Lead wire length can be from 2 cm to 13cm.
• Lead wires are bonded to bond pads on the rear surface of the array and potted with medical grade silicone elastomer.

Percutaneous Connectors:

• Twin connectors, each comprising a 38-lead edge connector mounted in a titanium pedestal (19 mm dia base, 11 mm dia body, 4.5 g).
• Lead wires potted in base of pedestal with silicone elastomer.

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Rat Connector: 32-Electrode Chronic Microelectrode Array Assembly

The Rat Connector is a 36-pin chronic percutaneous connector that measures 13mm x 7mm x 10mm and was designed for use in small animals such as rats.

Electrodes:

• Suggested 36 electrodes per array. (32 active electrodes.)

Lead Wires:

• 32 insulated, 1.0-mil Au/Pd wires, bonded to 32 electrodes.
• Lead wire length is specified by the customer (recommended between 20 and 80 mm).
• Wiring patterns of active electrodes customized to customer requirements.
• Lead wires are bonded to bond pads on the rear surface of array and potted with medical grade silicone elastomer.

Percutaneous Connectors:

• Printed circuit board connected to 36-pin connector (Omnetics Nanoconnector).
• Lead wires bonded to connector board and potted with medical grade silicone elastomer.

The chronic rat connector mates with a VLSI 2X amplifier headstage. This headstage minimizes noise and plugs into a flexible cable that transfers data to your amplifier.

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ICS-96: 96-Electrode Chronic Microelectrode Array Assembly

The ICS-96, a 108-pin chronic percutaneous connector that measures 37mm x 17mm x 8mm, was designed for use in large animals such as monkeys.

Electrodes:

• 100 electrodes per array.
• 96 active electrodes

Lead Wires:

• 96 insulated, 1.0-mil Au/Pd wires, bonded to 96 electrodes.
• Lead wire length is specified by the customer (recommended between 20 and 70 mm).
• Wiring patterns of active electrodes customized to customer requirements.
• Lead wires are bonded to bond pads on the rear surface of the array and potted with medical grade silicone elastomer.

Percutaneous Connectors:

• Three 36-pin connectors (Samtec FTSH series) mounted on a ceramic printed circuit board, surrounded by a polycarbonate shroud.
• Lead wires bonded to the connector board and potted with medical grade silicone elastomer.

The connector base is a ceramic printed circuit board, soldered to three 36-pin connectors that mate with three 1X amplifier headstages. These headstages minimize noise and plug into 0.050" cable strips to transfer data to your amplifier. The connectors are surrounded by a polycarbonate shroud that provides durability and strength. A protective hermetic cap prevents water, food and other particles from entering the connector, and provides protection from animal interference when the connector is not recording.

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General Description

The Cyberkinetics microelectrode arrays have been developed to record on a long-term chronic basis with multi-unit and single-unit responses of sensory, visual, and motor neurons in freely behaving animals. (They are also intended to be used to stimulate small groups of neurons in short term chronic applications.) The microelectrode arrays have been evaluated in dozens of implantations in rat visual / motor cortex / spinal cord, and feline sensory cortex, visual cortex, peripheral nerve, and in primate motor cortex, and visual cortex. The very large surface area of the array of penetrating electrodes, coupled with the array's very thin substrate, provides unusual chronic recording stability. Multiunit recordings have been made for periods of over three years (the longest periods studied).

The Cyberkinetics Microelectrode Arrays have a very large surface area that permits excellent, long term recording stability, but the high density electrode spacing makes it difficult to implant the arrays in neural tissues in a conventional manner. Trying to push the array into tissue 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 implant the arrays with a high-velocity insertion technique. Our pneumatically-actuated impulse inserter has been designed to use a momentum transfer technique to insert the 100-electrode arrays into feline and primate cerebral cortical tissues in under 300 microseconds. This high velocity insertion has been used in scores of array implantations and produces complete insertions of the array 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.

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