Deep-tissue light delivery via optrode arrays.

We establish performance characteristics of needle-type waveguides in three-dimensional array architectures as light delivery interfaces into deep tissue for applications, such as optogenetic and infrared (IR) neural stimulation. A single optrode waveguide achieves as high as 90% transmission efficiency, even at tissue depths >1  mm. Throughout the visible and near-IR spectrum, the effective light attenuation through the waveguide is ∼3 orders of magnitude smaller than attenuation in tissue/water, as confirmed by both simulation and experimental results.