Flexible optrode array: Parylene-film waveguide arrays with microelectrodes for optogenetics

We report a flexible thin-film device, which consists of an array of microelectrode/waveguide stacked `optrodes´ for optogenetic applications. Each electrode/waveguide-site enables simultaneous optical stimulation and electrical recording of neurons in the same alignment. Based on the calculations of the optical properties, we fabricated parylene-C(clad)/N(core)/C(clad) 18-μm-thick waveguides and confirmed the light propagation through the waveguides. The microelectrode embedded waveguide array shows the light propagation through the electrode exposed site, while the electrode exhibits the impedance of <; 2 kΩ at 1 kHz for neural recordings. These results indicate that the proposed flexible thin-film parylene-optrode array can be used for numerous biological tissues with a curvature, including brain and spinal cord.