Wireless Floating Microelectrode Array


The Wireless Floating Microelectrode Array (WFMA) is an implantable and fully tether-free 16-channel microelectrode array based upon the Microprobes for Life Science Floating Microelectrode Array (FMA), in which the wired percutaneous connector is replaced with a miniature integrated-circuit inductive telemetry unit resulting in a true wireless free-floating intracortical implant. The WFMA is by design intended to be implanted in large groups of up to 127 randomly addressable devices controlled and powered simultaneously by a single external command unit, creating a neuronal interface of up to 2,032 electrodes which can be carefully spread and positioned across a broad area of cortex. The WFMA can be configured in both purely-stimulating or hybrid stimulation/recording embodiments.

Wireless Floating Microelectrode Array


The WFMA was developed as an integral component of the IntraCortical Visual Prosthesis (or ICVP) Project, an over fifteen-year effort by eight institutions led by Philip R. Troyk (executive director of the Pritzker Institute of Biomedical Science and Engineering at the Illinois Institute of Technology), together with Rush University Medical Center, the Chicago Lighthouse, the Wilmer Eye Institute at Johns Hopkins, the University of Texas at Dallas, Sigenics Inc., the University of Chicago, and Microprobes for Life Science Inc. Envisioned as the culmination of over three decades of work at IIT and the NIH toward the development of a system capable of providing artificial sight to those with eye injury or disease-related blindness, the ICVP project reached a crucial milestone in February of 2022 when the system was surgically implanted into a human volunteer for the first time as part of a Phase I Feasibility Study of an Intracortical Visual Prosthesis for People With Blindness. 25 WFMA stimulation devices were chronically implanted into the visual cortex of the subject for a total of 400 electrodes.


Each WFMA is a miniature 16-channel device with its own command address. The device is essentially a hybrid ASIC/FMA, with a telemetry unit and transmission coil mounted directly to the backside of a floating array and thus eliminating the tether. The entire device is only 5mm in diameter with a low profile optimized for cortical implantation under dura. The system has several key advantages:

[list icon="licon: arrows-right-double-31"]
  • Extremely modular design, allowing the ASIC chip and each individual electrode in the array to be custom tailored for the application, subject, and implant location.
  • Each individual electrode can be customized with regard to length, metal, impedance, and tip shape.
  • Arrays can be uniform in length, or an infinite number of other configurations including slanted, staggered, clustered, or carefully contoured to match the anatomy of the target.
  • Metal options include platinum/iridium and activated pure iridium, insulated with Parylene-C.
  • The ICVP study WFMAs feature parylene-C insulated activated iridium electrodes laser exposed using a dual-beam excimer and shaped using the “goldilocks” process to achieve a precise and repeatable shape and exposure area.
  • Transcutaneous-link coil is made of 25-micron polyimide insulated gold wire, providing power and bi-directional telemetry.
  • Packaging is accomplished through vacuum-molding a strongly adherent addition-cure PDMS to encapsulate the device following extensive plasma cleaning. The ASIC chip contains all needed circuitry with no external components necessary.


[list icon="licon: arrows-right-double-31"]
  • Illinois Institute of Technology
  • Rush University Medical Center
  • The Chicago Lighthouse
  • The Wilmer Eye Institute at Johns Hopkins
  • The University of Texas at Dallas
  • The University of Chicago
  • MicroProbes for Life Science, Inc.
  • Sigenics, Inc.
[/list] Funding for this study was provided by the National Institutes of Health’s Brain Research through Advancing Innovative Neurotechnologies® (BRAIN) Initiative, the Department of Defense and from private donors. Research reported in this publication was supported by the NIH (BRAIN) Initiative under Award Number UH3NS095557. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.