The precise control of neural activity afforded by the use of light sensitive ion channels such as Channel Rhodopsin
(ChR2) offers neuroscientists the means to devise new experiments. In this paper we present the Optogenetic Neural
Stimulation (ONS) platform which enables complex in-vitro or ex-vivo investigation of neural activity. The platform is
based on micro-meter sized Light Emitting Diodes (LEDs) integrated onto a single Gallium Nitrite chip. Mounted onto a
microscope system, this system can be used to carry out experiments on networks of cells, or on sub-cellular regions of a
neuron with millisecond timing and micrometer resolution.
This paper highlights how the genetic incorporation of artificial opsins into the retina can lead to a new class of retinal prosthesis. We demonstrate the efficacy of incorporating channelrhodopsin into neuron cells in-vitro and show how that can be scaled to in-vivo. We show that we need typically 100mW/cm<sup>2</sup> of instantaneous light intensity on the neuron in order to stimulate action potentials which results in 10W/cm<sup>2</sup> required from the light source. We thus use GaN LED arrays to provide spatially controlled stimulation which is of sufficient brightness to stimulate the cells.