Multi-Part Implant

The Multi-Part Implant comprises Implanted Internal Electronics Unit and 1 or 2 ECoG electrodes plus one optional ground (GND) electrode contact.

Information

Electrodes

Similar to CorTec’s FDA cleared °AirRay Cortical Electrode all electrodes based on the °AirRay electrode technology are capable of recording and stimulating brain activity. Produced in a proprietary laser manufacturing process, °AirRay electrodes are very soft, thin and flexible. They adapt well to the brain‘s curvature.

According to your requirements, customized electrodes can be tailored to fit the needs of your specific system design.

In addition to the use of CorTec electrodes, the system can also be equipped with DBS electrodes. A validation of the interconnection of the Brain Interchange implant to a connection cable for market approved DBS electrodes can be executed upon request.

Implanted Internal Electronics Unit

The Implanted Internal Electronics Unit consists of a hermetically sealed ceramic encapsulation, electronics and firmware. It is powered wirelessly and communicates via a radio-frequency link.

The Implanted Internal Electronics Unit with hermetic package, inductive power receiving coil, and electrode interconnection area is placed underneath the scalp, partly embedded in the skull. The electrodes implanted on the surface of the brain are in direct contact with the central nervous system. When used as intended, the Internal Electronis Unit will be permanently implanted approximately 4 cm above the tragus of the mastoid cavity.

For long-term stability, the implant electronics are protected against body fluids by a hermetic encapsulation. Device safety is monitored by multiple sensors inside the hermetic package.

Materials

°AirRay electrodes are made from silicone and platinum-iridium (90:10). Other contact materials or coatings can be provided upon request. For some designs the use of a hybrid silicone-Parylene C substrate is the recommended solution.

The ground electrode consists of a ring made from platinum-iridium (90:10) located at the end of a medical-grade silicone tube. It is connected to the Implanted Internal Electronics Unit.

The Implanted Internal Electronics Unit is casted in medical-grade silicon rubber. It contains a hermetic ceramic encapsulation to protect the electronic circuits.

The °AirRay ECoG electrodes are made from platinum-iridium (90:10), medical-grade silicone rubber and Parylene C. Connection cables consist of individually insulated wires bundled in medical-grade silicone tubing.

Functionality

Recording and Stimulation

The System is able to record and stimulate with each of the 32 channels.

Stimulation is enabled by current controlled, biphasic, rectangular, asymetric stimulus pulses (cathodic amplitude I with pulsewidth followed by an anodic counter pulse of 1/4x amplitude and 4x  pulsewidth). One current source can be directed to any of the 32 electrodes. The current return path is any of the 32 electrodes or groups of electrodes or an additional counter electrode.

More detailed specifications are available upon request. Please use our contact form to send us you request.

Implanted Device Impedance Measurement

The Brain Interchange System measures the impedance of electrodes on user demand.

Amplifier input impedance
– 
AC Impedance: 15pF capacitance
– 0.1 Hz: 100 GOhm
– 1 Hz: 10 GOhm
– 10 Hz: 1 GOhm
– 100 Hz: 100 MOhm
– 450 Hz: 24 MOhm

Implanted Device Electrode Breakage Detection

The Brain Interchange System ensures patient safety even in case of a broken electrode contact.

Impedance testing identifies defect contacts which will be automacillay excluded from ongoing electrical stimulation treatment. The System requests the user to decide about how to go on for the blocked contacts.

Technical Specifications

Recording channels: 32

Sampling rate: 1 kHz

Sampling dynamic range: 16 bit (74 nV smallest increment)

High pass filter cut-off: 0.1 Hz

Low pass filter cut-off: 450 Hz

Amplifier band pass gain: 631

Band pass roll-off: 20 dB/dec

Stimulation channels: each of the 32
(concurrent stimulation at 4 channels: 3 predertermined channels, 1 switchable to any of the 32 electrode contacts)

Stimulation type: Current controlled stimulation

Current: Max. -6 mA / +1.5 mA within compliance voltage range of -11V to +5V

Shape: Biphasic, charge balanced

Pulse width: Negative phase: 10 µs – 2,500 µs, Positive phase: 4 times the duration of the negative phase, with 1/4 of the amplitude of the negative pulse

Implant max. power uptake: Typical: < 400 mW

Method of impedance test: Voltage response to current pulse

Thermal monitoring: Protection against overheating

Electrical Isolation of patient from electronics: DC-decoupled using blocking capacitors

Power supply: Wireless inductive, 120-140 kHz

Wireless data transmission: Bi-directional, radio frequency in 2400-2483.5 MHz band

Min. device lifetime: 2 years

Implant size (capsule with coil): 65 mm x 67 mm x 7 mm (max. dimensions)

Surface Area: 7600 mm2

Implant weight: 50-60 g (similar to pacemaker)

Contact

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R&D

Our research and development activities are based on a long-term cooperation of neuroscientists, engineers and physicians of the University of Freiburg.

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