A sapphire based monolithic integrated optrode.

A novel kind of optrode fabricated on a sapphire substrate is proposed for optogenetic applications in neuroscience. Eight thin-film neural electrodes and a GaN-LED are monolithically integrated on the surface of a sapphire shank. The LED is used for optogenetic stimulation and the multiple electrodes are used for simultaneous recording of neural activities. The output power density of the LED is 1-19 mW/mm(2) at 468 nm, driving with a current from 0.7-10 mA. The mean electrochemical impedance of the eight recoding sites on the optrode at 1 kHz is 385 kΩ. The highest temperature-raise at tissue around the LED is almost 1 °C when the output power density is 3 mw/mm(2). The monolithic integrated structure will make it a powerful tool for optogenetics.