Engineers at Stanford University are working on a new generation of medical devices that would be planted deep inside the body to monitor illness, deliver therapies and relieve pain. But in order to do so, they need to develop a way to provide electric power to those implants. Using wires or batteries to deliver power generally makes implants too big, too clumsy, or both, they say.

Stanford engineers can power this prototype medical implant chip without wires by using ultrasound.

Their solution is to develop a method to send power safely to “smart chips” programmed to perform medical tasks and report back the results. Their approach involves beaming ultrasound at a tiny implanted device designed to: convert the incoming sound waves into electricity; process and execute medical commands; and report the completed activity via a tiny built-in radio antenna.

To do so, they chose ultrasound to deliver wireless power to their medical implants because it has been safely used in many applications, and can provide sufficient power to implants a millimeter or less in size.

The Stanford chip is powered by “piezoelectricity,” or electricity caused by pressure. In a piezoelectric material, pressure compresses its molecular structure. When the pressure lessens, the material’s molecular structure pops back into shape.

Each time a piezoelectric structure is compressed and decompressed, a small electrical charge is created, functioning as the power delivery mechanism.

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