Modeling brain tissue scattering for optical neural interfaces

The possibility to optically control and monitor neural activity with optogenetic methods has generated the need for new implantable devices to deliver and collect light from neural tissues. This is being accompanied by a set of methods that allow to numerically predict and experimentally test how light emitted by implanted optoelectronic devices, semiconductor waveguides and optical fibers behave in a highly scattering medium like the brain tissue. After discussing the most common scattering models, this work focuses on how emission and collection properties of optical fibers implanted the brain can be estimated. To assess photometry efficiency fields of an optical fiber implanted in a turbid medium, we combine numerically evaluated light emission and collection fields in presence of scattering. This approach can help to complement current knowledge on the influence of tissue scattering on the optical properties of implanted photonics devices, providing additional information for the design of optical bidirectional neural interfaces.