Resonant Based Light Amplification for a High Resolution Optical Retinal Prosthesis

Optogenetics based retinal prostheses, which rely on the activation of light gated channels such as ChR2, have been introduced as a means for sight restoration in patients with retinal degeneration. However, current technologies are based on projecting high-power blue light, which may damage the intraocular tissue. Here, we present two models of devices designed for local enhancement of light field on the neuron membrane, aimed at significantly decreasing light-threshold for neural activation. The first design is based on 2D array of local plasmone resonance (LPR), created by noble metal nanoparticles and the second is a micro-mirror resonator. A combined numerical simulation tool based on CST MW and COMSOL Multiphysics softwares was developed to calculate the local amplification of light-field in the neuronal membrane and the induced increase in membrane potential biophysical model in response to light activation. Results show that light intensity was amplified by up to two orders of magnitude, allowing a decrease of one order of magnitude in the neural threshold intensity-duration curve. This approach opens novel opportunities for future application of neural prostheses in general and for the retinal in particular.