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The proposed WOENI device is potentially a versatile tool in the studies that involve long-term optogenetic neuromodulation.

Optogenetics is a fast growing neuromodulation method, which can remotely manipulate the specific activities of genetically-targeted neural cells and associated biological behaviors with millisecond temporal precision through light illumination. Application of optogenetics in neuroscience studies has created an increased need for the development of light sources and the instruments for light delivery. This paper presents a micro-lens-coupled LED neural stimulator which includes a backside reflector and a frontside microlens for light collection and collimation. The device structure has been optimized using optical simulation and the optimized device is able to increase the volume of excitable tissues by 70.4%. Device prototypes have been fabricated and integrated based on an optimization of the device structure. The measurement results show that the light power increases by 99% at an effective penetration depth of 5 000 [Formula: see text] by the fabricated device under various voltages of 2.4-3.2 V.

We introduce a single channel neuro-stimulator consisting of a reflector-coupled microscale light emitting diode (µLED) 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 µLED provides significant light intensity enhancement compared to a bare µLED. Our activated stimulators have an operational temperature increase of <1 °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.

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