High density optrode-electrode neural probe using SixNy photonics for in vivo optogenetics.

Luis Hoffman, Marleen Welkenhuysen, Alexandra Andrei, Silke Musa, Zhenxiang Luo, Sarah Libbrecht, Simone Severi, Philippe Soussan, Veerle Baekelandt, Sebastian Haesler, Georges Gielen, Robert Puers, Dries Braeken
IEEE International Electron Devices Meeting 2015, 2015

Moore’s law in neural sciences: we present an optical neural probe (optoprobe) with the highest integration density of optrodes-electrodes using a CMOS process platform in 193nm lithography. We designed, developed, and packaged an ultrathin (30 µm) optical neural probe, co-integrating silicon nitride (SixNy) photonics and biocompatible titanium nitride (TiN) electrodes (1). Functionality was verified in vivo by optically evoking and electrically recording neuronal activity in a mouse brain. Our design takes advantage of CMOS technology and incorporates 12 miniaturized optical outputs (optrodes) placed symmetrically next to 24 recording electrodes on a narrow 100-µm wide shank. We achieved an unprecedented optrode density by integrating grating couplers (GCs) instead of traditional end-butt coupling. The size of each optrode and electrode is 6 x 20 µm2 and 10 x 10 µm2 respectively, which is the typical size of a neuron. The system was capable of local excitation and recording of transduced neurons, a breakthrough achieved by the high-density integration.

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