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 193 nm lithography. We designed, developed, and packaged an ultrathin (30 μm) optical neural probe, co-integrating silicon nitride (Si_xN_y) 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 × 20 μm² and 10 × 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.