Medical implants, particularly of the active and smart variety, typically require a source of electricity to power their sensors and other components. Lithium-ion batteries have been the most common option, particularly for cardiac devices, but they don’t last forever and often have to be replaced or recharged somehow. Inductive charging has been around for a while now, but its efficiency is lacking and it can cause dangerous heat build-up around the object being charged. Moreover, even having a battery on-board can make a device considerably larger than its core components. Researchers from at Stanford University have now developed a new way to harness the energy delivered using an ultrasound probe to power tiny implants deep within the body and even send them commands the same way.
The technology can power devices smaller than 1 mm on a side, which can be developed to analyze all sorts of aspects of the body’s biochemical and electrical processes. It uses the concept of piezoelectricity, which allows certain materials to turn mechanical stress into an electric current, to apply pressure onto a tiny spring using ultrasound waves. The electricity coming out of the spring can power the implant and, by modulating it via the ultrasound probe, can be used as a signal transmitter to send instructions to the implant. The implant also has a radio antenna that can be used to send readings and messages to an external wireless receiver.
The researchers are now working on minimizing the implants even further to be able to safely implant the brains of laboratory animals and maybe come up with devices that can track various neurological conditions.
White paper: A mm-Sized Implantable Device with Ultrasonic Energy Transfer and RF Data Uplink for High-Power Applications (.pdf)
Press release: Stanford engineers develop tiny, sound-powered chip to serve as medical device…
