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Two prominent Stanford researchers, Ada Poon and Karl Deisseroth, recently teamed up to create a completely wireless optogenetic implant. Instead of relying on fiber optic tethers and bulky headset receivers, their tiny mouse stimulator generates light from LEDs that are powered with an ingenious technique: a 1.5 GHz RF cavity that couples energy to the implant by using the whole mouse as an efficiently matched receiver.

In contrast to more conventional inductive energy transfer systems that need to have direct coupling between two opposed coils, the animal is free to move about anywhere above the energizing lattice in the floor of its chamber. But this is not just some scaled-down version of a subsurface highway charger for electric vehicles. Instead, resonant excitation of a confined electromagnetic field pattern (i.e. its intrinsic mode) can be localized to the mouse independent of its position.

It’s all in a closed-access paper Poon previously published not so long ago. We are not yet sure how to scale this up to humans. But as long as our dielectric properties are similar, the main variable should just be physical dimension. Provided you get that right, and have a way to get a few opto-enabled ion channels — preferably the channelrhodopsin 2 (ChR2) variety — into select parts of your nervous system, the actual hardware to rectify sufficient power for the LEDs is fairly simple.

In fact, all you need to boost up the raw DC voltage is four Schottky diodes and four capacitors configured into a two-stage doubling circuit. Together with three small turns for the antenna receiver, everything should fit into 10 mm3 package that weighs under 20mg. As the researchers show in their actual experimental paper, that’s small enough to fit nearly anywhere in the central or peripheral nervous system, even just under the skin at sensory nerve endings.

Just to make sure everything is on the up and up, you may initially want to use a bit of exploratory fiber optics anyway. They make for a highly accurate and localized temperature probe. In the course of due diligence, the researchers demonstrated that any incidental temperature rises associated with the stimulation were limited to Deisserothfor several years now. The technological fruits now falling out of their mutual labor, while clearly awesome just to behold, are even more seductive when we can fully view them in their transparent simplicity with an eye to one day possess.

Read more http://www.extremetech.com/extreme/212448-stanford-researchers-build-fully-internal-optical-brain-interfaces