A Miniaturized, Wirelessly-Powered, Reflector-Coupled Single Channel Opto Neurostimulator

We report a free-floating, wirelessly-powered, single channel opto neurostimulator consisting of a reflector coupled microscale light emitting diode (mu LED) and a mm sized receiver (Rx) coil for untethered optogenetics neuromodulation. An optimized two-coil inductive link delivers over 4 mW instantaneous power at a low operating frequency to continuously drive the mu LED while minimizing device invasiveness and tissue exposure to electromagnetic radiation. The reflector-coupled mu LED enables significantly enhanced light intensity compared to a bare mu LED. The temperature increase of the activated stimulators is <1 degrees C, well below the safety limit of biomedical implants. In vivo experiment and histological analysis verify the efficacy of wireless optical stimulation in the rat cortex, using c-Fos as a report of light-evoked neuronal activity.