Bi-directional Optrode for quantitative prediction of neural interface failure

An optical-electrical neural `Optrode' is developed for quantitative optical spectroscopic assessment of cortical tissue damage around a neural implant. In contrast to other Optrodes which illuminate tissue for neural activation, this work uses bi-directional waveguides to obtain spectroscopic information from the tissue. An optical assessment has the potential for providing a real-time histological assessment, by quantifying changes in absorption and scattering properties associated with oxygenation and tissue density around the neural probe, in contrast to impedance spectroscopy which provides limited insight. Optrode performance is characterized in optical tissue phantoms and a proof-of-concept chronic rat model is developed. Optrodes were chronically implanted in rat cerebral cortex. The pilot study demonstrates feasibility for chronic optical assessment. Future Optrodes may lead to high throughput and real-time assessments for studying the dynamic nature of the foreign body response in neural tissue.