Fabricating High-density Microarrays for Retinal Recording

Mathieson, K., Cunningham, W. , Marchal, J., Melone, J., Horn, M., O'Shea, V. , Smith, K.M., Litke, A., Chichilnisky, E.J. and Rahman, M. (2003) Fabricating High-density Microarrays for Retinal Recording. In: 28th International Conference on Micro and Nanoengineering, Lugano, Switzerland, 16-19 September 2002, 520 -527. (doi:10.1016/S0167-9317(03)00109-6)

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Publisher's URL: http://dx.doi.org/10.1016/S0167-9317(03)00109-6

Abstract

Understanding how the retina encodes the visual scene is a problem, which requires large area, high-density microelectrode arrays to solve. The correlated signals that emerge from the output (ganglion) cells of the retina form a code, which is not well understood. We use a combination of electron beam lithography, photolithography and dry-etch pattern transfer to realise a 519-electrode array in the transparent conductor indium tin oxide (ITO). The electrodes are spaced at 60 mum in a hexagonal close-packed geometry. A mix and match lithography procedure is utilised, whereby the high-density inner region is fabricated using electron beam lithography whilst the outer sections are realised by photolithography. Reactive ion etching (RIE), using CH4/H-2, of the ITO forms the array structure and SF6 RIE allows resist removal and patterning of vias through a plasma deposited Si3N4 protective layer. The electrical properties of the ITO layer are unaffected by the etching procedures. A reliable method for achieving low-impedance electroplated platinum electrodes has been employed to yield electrode impedances of similar to 20 kOmega. An array fabricated using these dry-etch techniques is shown to record action potentials from live retinal tissue in neurophysiological experiments.

Item Type:Conference Proceedings
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Smith, Professor Kenway and O'Shea, Professor Val and Cunningham, Dr Liam and Mathieson, Dr Keith and Melone, Mr John
Authors: Mathieson, K., Cunningham, W., Marchal, J., Melone, J., Horn, M., O'Shea, V., Smith, K.M., Litke, A., Chichilnisky, E.J., and Rahman, M.
Subjects:Q Science > QC Physics
Q Science > QP Physiology
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Microelectronic Engineering Proceedings 28th Int.Conf. Micro - and Nano-Engineering Lugano, Switzerland Sept 2002
ISSN:0167-9317

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