Implant gets energy from sound waves

Stanford researchers have developed an implant that can be supplied with energy using ultrasonic sound waves. Their prototype is a few millimeters in size, but with future incarnations, the implants should be reduced to ‘smart chips’.

The prototype of the Stanford University staff is about eight by four millimeters in size and 2.5 millimeters thick. It has not yet been implanted in humans, but chicken breast has been used as tissue. The device is powered by ultrasound, similar to the ultrasound sources used for echoes. Sound waves set a piezoelectric receiver in motion, which generates electricity. A circuit regulates that energy, delivering a maximum of 100 microwatts, with an efficiency of 54 percent. The researchers opted for an external energy source, because batteries often make implants too large.

That energy can be used for medical applications: for example, the implantable smart chips could deliver localized electrical pulses to combat pain. Of course, the chips can also be used to monitor bodily functions. The readings can then be sent to an external device via a built-in transmitter, so that immediate feedback on treatments can be gathered. To enable further miniaturization, the researchers have already experimented with smaller antennas for the piezoelectric receiver: a 0.7mm by 0.7mm version also worked.