Thermal and optical characterization of micro-LED probes for in vivo optogenetic neural stimulation

McAlinden, Niall and Massoubre, David and Richardson, Elliot and Gu, Erdan and Sakata, Shuzo and Dawson, Martin D and Mathieson, Keith (2013) Thermal and optical characterization of micro-LED probes for in vivo optogenetic neural stimulation. Optics Letters, 38 (6). pp. 992-994. (https://doi.org/10.1364/OL.38.000992)

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Abstract

Within optogenetics there is a need for compact light sources that are capable of delivering light with excellent spatial, temporal, and spectral resolution to deep brain structures. Here, we demonstrate a custom GaN-based LED probe for such applications and the electrical, optical, and thermal properties are analyzed. The output power density and emission spectrum were found to be suitable for stimulating channelrhodopsin-2, one of the most common light-sensitive proteins currently used in optogenetics. The LED device produced high light intensities, far in excess of those required to stimulate the light-sensitive proteins within the neurons. Thermal performance was also investigated, illustrating that a broad range of operating regimes in pulsed mode are accessible while keeping a minimum increase in temperature for the brain (0.5°C). This type of custom device represents a significant step forward for the optogenetics community, allowing multiple bright excitation sites along the length of a minimally invasive neural probe.