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Tiny 'Innerspace' devices are small enough to power through your bloodstream

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Stanford researcher Ada Poon is demonstrating wirelessly-powered devices small enough to travel through the human bloodstream at ISSCC in San Francisco.

innerspace 1020
innerspace 1020

What doctor wouldn't want to implant a motorized device inside his or her patient’s vasculature? It would be perfect for delivering drugs or sensors, busting blood clots, or removing plaque, but it’s always been thought impossible because of the perceived difficulty in passing high-frequency radio waves through human tissues. Well, Stanford researcher Ada Poon not only made it happen (she showed off the new tech at ISSCC on Tuesday), she managed to upend conventional theory in the process.

To power an implanted device without bulky batteries you could use a magnet to induce a charge using the principle of inductive coupling. However, the device would need an antenna, and to get enough power, conventional models call for one a few centimeters in diameter; clearly too big to be traveling through anything but your biggest arteries. Poon re-evaluated some long-held beliefs about the human body's insulating properties and found that it actually functions as a dielectric — a kind of insulator. So while our tissues don’t conduct electricity so well, they’re pretty good at letting through high-frequency radio waves, meaning that an antenna only has to be about a hundredth as large as originally thought.


So far, Dr. Poon has developed devices (pictured above) using two kinds of propulsion — one passes a current through the fluid to move the device along, while the other switches current back and forth in a wire loop, creating a motion similar to "a kayaker paddling upstream." While the technology is still a long way off from any kind of medical application, Dr. Poon believes "we're closer than ever." Now we just need to take care of micronization.