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