Integrated Flexible Optitrode for Neural Stimulation and Recording

We present an integrated flexible probe for deep brain optical stimulation and electrical recording, termed as "Optitrode". This device features an annular light guide consisting of layered transparent polymer and silica, and is fabricated by a unique process we developed: V-groove guided capillary assembly (VGCA), by which a single or multiple microwires can be integrated inside the light guide with high precision. The Optitrode design promises an ultrahigh length-to-diameter ratio > 500 (5 cm long, < 100 mu m diameter), enabling minimally-invasive deep brain applications. Furthermore, the highly flexible nature of Optitrode could address a current barrier in rigid brain implants with limited life-time by conforming to the brain micromotion during long-term operation.