An implantable optrode composed of fiber and flexible thin-film electrode

An implantable optrode composed of fiber and multi-channel flexible thin-film electrode is developed. The flexible recording electrode is made from polyimide and is wrapped around the optical fiber. The front end of the fiber is tapered by wet etching. With the tapered shape, the light can leak from the sidewall of the fiber, and the tapered tip makes it easy to be implanted. The flexible electrode is attached with its recording sites aligning to the tapered part on the fiber. With this method, the fiber acts as an optical waveguide, as well as a support probe for flexible thin-film electrode. This novel device simplifies the fabrication process and decreases the size of the optrode. The device works well in vivo and the optical caused spike can be recorded with signal-to-noise ratio of 6:1.