Inductively coupled, mm-sized, single channel optical neuro-stimulator with intensity enhancer

We introduce a single channel neuro-stimulator consisting of a reflector-coupled microscale light emitting diode (mu LED) with an integrated mm-sized wireless receiver (Rx) coil for free-floating, battery-free, untethered optogenetics neuromodulation. The system utilizes a two-coil inductive link to deliver instantaneous power at a low operating frequency (<100 MHz) for continuous optical stimulation with minimized invasiveness and tissue exposure to electromagnetic radiation. Coupling a microscale reflector to the mu LED provides significant light intensity enhancement compared to a bare mu LED. Our activated stimulators have an operational temperature increase of <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 primary visual cortex of rats, using c-Fos biomarker as a reporter of light-evoked neuronal activity.