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Proceedings Paper

A compact integrated device for spatially selective optogenetic neural stimulation based on the Utah Optrode Array
Author(s): Robert Scharf; Christopher F. Reiche; Niall McAlinden; Yunzhou Cheng; Enyuan Xie; Rohit Sharma; Prashant Tathireddy; Loren Rieth; Keith Mathieson; Steve Blair
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Paper Abstract

Optogenetics is a powerful tool for neural control, but controlled light delivery beyond the superficial structures of the brain remains a challenge. For this, we have developed an optrode array, which can be used for optogenetic stimulation of the deep layers of the cortex. The device consists of a 10×10 array of penetrating optical waveguides, which are predefined using BOROFLOAT® wafer dicing. A wet etch step is then used to achieve the desired final optrode dimensions, followed by heat treatment to smoothen the edges and the surface. The major challenge that we have addressed is delivering light through individual waveguides in a controlled and efficient fashion. Simply coupling the waveguides in the optrode array to a separately-fabricated μLED array leads to low coupling efficiency and significant light scattering in the optrode backplane and crosstalk to adjacent optrodes due to the large mismatch between the μLED and waveguide numerical aperture and the working distance between them. We mitigate stray light by reducing the thickness of the glass backplane and adding a silicon interposer layer with optical vias connecting the μLEDs to the optrodes. The interposer additionally provides mechanical stability required by very thin backplanes, while restricting the unwanted spread of light. Initial testing of light output from the optrodes confirms intensity levels sufficient for optogenetic neural activation. These results pave the way for future work, which will focus on optimization of light coupling and adding recording electrodes to each optrode shank to create a bidirectional optoelectronic interface.

Paper Details

Date Published: 14 February 2018
PDF: 9 pages
Proc. SPIE 10482, Optogenetics and Optical Manipulation 2018, 104820M (14 February 2018); doi: 10.1117/12.2299296
Show Author Affiliations
Robert Scharf, The Univ. of Utah (United States)
Christopher F. Reiche, The Univ. of Utah (United States)
Niall McAlinden, Univ. of Strathclyde (United Kingdom)
Yunzhou Cheng, Univ. of Strathclyde (United Kingdom)
Enyuan Xie, Univ. of Strathclyde (United Kingdom)
Rohit Sharma, The Univ. of Utah (United States)
Prashant Tathireddy, The Univ. of Utah (United States)
Loren Rieth, The Univ. of Utah (United States)
Keith Mathieson, Univ. of Strathclyde (United Kingdom)
Steve Blair, The Univ. of Utah (United States)

Published in SPIE Proceedings Vol. 10482:
Optogenetics and Optical Manipulation 2018
Samarendra K. Mohanty; Nitish V. Thakor; E. Duco Jansen, Editor(s)

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