MRS Bulletin

Materials for Neural Interfaces

Materials for Neural Interfaces

Thin films and microelectrode arrays for neuroprosthetics

Juan Ordoneza1, Martin Schuettlera2, Christian Boehlera3, Tim Boretiusa4 and Thomas Stieglitza5

a1 Department of Microsystems Engineering, Laboratory for Biomedical Microtechnology, University of Freiburg, Germany; ordonez@imtek.de

a2 Department of Microsystems Engineering, Laboratory for Biomedical Microtechnology, University of Freiburg, Germany; schuettler@ieee.org

a3 Department of Microsystems Engineering, Laboratory for Biomedical Microtechnology, University of Freiburg, Germany; christian.boehler@gmx.de

a4 Department of Microsystems Engineering, Laboratory for Biomedical Microtechnology, University of Freiburg, Germany; boretius@imtek.de

a5 Department of Microsystems Engineering, Laboratory for Biomedical Microtechnology, University of Freiburg, Germany; stieglitz@imtek.de

Abstract

Complex prosthetic limbs, the bionic eye, or brain-computer interfaces implement microelectrode arrays to connect the nervous system to an electronic device. The aim is to partly restore lost body functions or to gather bioelectrical activity from the nervous system. Microelectrode arrays are fabricated to have specific electrical and mechanical properties to match the biological requirements of the intended application. Polyimide and parylene-C are favorable polymers for substrate and insulation layers in thin-film applications. This article reviews the materials and the mechanical and electrical properties of electrode arrays. It emphasizes the often ignored but crucial influence of adhesion of the thin-film layers on the device’s longevity and reliability. Adhesion promotion techniques using layers of silicon carbide (SiC) are also discussed. Even though the main focus is on thin-film devices fabricated using traditional methods of micromachining based on lithography, an alternative to thin films, laser-patterned silicone/metal foil microelectrode arrays, is also presented. Characterization as well as application examples of these devices are also presented.

(Online publication June 08 2012)

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