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Intracortical Visual Prosthesis: The Clinical Trial The ICVP Project

Microprobes is honored to be one of the seven team members of the IntraCortical Visual Prosthesis (ICVP) project which received NIH funding to proceed with the first human clinical trial of the implantation of miniature wireless 16-channel stimulation modules into the occipital lobe for the purpose of providing visual perception to people with blindness.

Team Partner Institutions.jpg
ICVP Project
The ICVP system: Neurons in dorso-lateral region of occipital lobe are stimulated by electrodes contained within Wireless Floating Microelectrode Arrays (WFMA) electronic modules.
WFMA next to US penny
Photograph of WFMA next to US penny as viewed from the top. Visible are the ASIC and power/telemetry coil.

WFMA PHYSICAL FEATURES

WFMA from the Intracortical Visual Prosthesis System
Internal structure of the WFMA
Typical Iridium electrode exposed by laser
Using microfabrication technology at Microprobes for Life Science, the WFMA can be custom-configured with user-specified electrode lengths and shapes.

  Left   WFMA from the Intracortical Visual Prosthesis System (ICVP) using 1.5mm electrodes and longer guide pins.   Center   Internal structure of the WFMA.   Right   Typical Iridium electrode exposed by laser.

IIT Intracortical

IIT Intracortical Visual Prosthesis Module

Design of the Intracortical wireless stimulator module. The position of 16 AIROF electrodes, plus Pt-Ir counter and reference electrodes, are maintained within the ceramic substrate superstructure. The electrode shafts are insulated with Parylene-C and the tips of the Ir electrodes are exposed with a solid state laser.

The transcutaneous-link coil is fabricated from 25-micron heat-fusible polyimide Au wire, and is used to provide power and bi-directional telemetry. The ASIC chip contains all needed circuitry with no external components. Packaging of the module is accomplished by vacuum molding of the plasma-cleaned assembly using a strongly adherent addition-cure PDMS.. Final module is 5mm diameter, and ~0.5-mm thick.

Activated Iridium Oxide Electrode design

Activated Iridium Oxide Electrode design

  • Parylene-C insulated iridium shaft with AIROF tip.
  • 2000 sq. micron laser-exposed surface area.
  • Activation of iridium performed over the wireless link.
  • “Goldilocks” blunt-tip electrode displaces blood vessels upon insertion.
  Top   Before activation;   Down   After activation
CAD drawing of the ASIC for the wireless module

CAD drawing of the ASIC for the wireless module

  • Each of the 16 electrodes is driven by a dedicated compliance-supply-limited constant-current driver.
  • Power Link Frequency: 4.8MHz; FSK modulation – 1.2Mbits/sec.
  • Power Supply: 5V; 2.5nF on-chip capacitance.
  • Electrode Drivers: 16 independent drivers; constant current cathodic-first with subsequent recharge and biasing of the electrodes.
  • Stimulus Pulse amplitude: 64 uA maximum in 0.5 uA steps.
  • Pulsewidth: 750 usec maximum in 50 usec steps.
  • Arbitrary Waveshape possible.
  • Outward Telemetry: 150kHz carrier; Pulse duration modulation; power supply and electrode voltage monitoring.
  • Intrinsic Capability for Activation of AIROF Electrodes over Wireless Link.
  • Fabrication Technology: Xfab CX08.

SURGICAL IMPLANTATION

WFMA zoom
WFMA view
Photographs taken immediately following implantation of the WFMA devices in NHP brain for two animals. WFMAs were implanted in motor cortex near the central sulcus. No surface blood vessel bleeding was observed during surgery, despite the insertion of the WFMAs directly over blood vessels. Devices have been implanted for 10 months without functional deterioration (test on-going).
Before Implant
After Implant
WFMA collage
Photographs taken immediately following implantation of the WFMA devices in Human Cadaver. Devices can be implanted with as close as 0.1mm spacing. Note conformance with surface of gyri. Nine WFMAs were implanted in less than 10 minutes.   Far right  WFMAs after extraction from cadaver showing no damage to electrodes.

Insertion Tool Technology

Array Collet System

WFMA setup
  A   WFMA loaded in collet;   B   Tool tip prior to loading;   C   Collet loaded into tool;   D   Empty collect following insertion, prior to ejection.
WFMAs are preloaded into protective collets.
WFMAs are preloaded into protective collets. The collets easily load into the tool tip just prior to implantation. The WFMA is inserted via rapid acceleration at 1m/sec. The collect is ejected from the tool, and the next WFMA/collect is then loaded. readying the tool for another implantation.

* The ICVP project is supported by the National Institute Of Neurological Disorders And Stroke of the National Institutes of Health under Award Number UG3NS09555. The content here is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

For more information about the ICVP project please call: (312) 567-5304.