Many implanted medical devices get energy from batteries, which eventually run down. Beaming energy through the skin is a useful alternative, especially for supplying cochlear implants, which require about 70 mW of power. Here the issue is whether to go with energy in the form of radio waves (RF) or ultrasound. For both methods about 10-12 percent of the beamed energy gets lost on the way as it moves through several millimeters of tissue, usually by being scattered rather than being absorbed. In both systems the overall energy efficiency is about 40-50 percent.
Rob Adamson, a researcher at Dalhousie University in Halifax, Canada, prefers the ultrasound approach, since the power source is much smaller: the RF coils are typically 5 cm in diameter, compared to 5 mm for the ultrasound source. Furthermore, the RF setup often requires an extra magnet (to keep the coils aligned), and this precludes the patient having an MRI scan performed without having the implant removed.
Adamson's ultrasound beaming device is not yet in clinical trials, but his lab is affiliated with an ear surgeon.
"We are reporting successful experiments in delivering power across a water bath using ultrasound with 38 percent efficiency," says Adamson.
The ultrasound approach might be useful for supplying energy to other such as artificial hearts.
The talk "A miniature, ultrasonic transcutaneous energy transmission system for powering implantable medical devices (1pBB9)" by Rob Adamson is at 3:50 p.m. on Monday, November 15.
8) Repelling Divers with the Sound of Their Breath
At the Stevens Institute of Technology in Hoboken, New Jersey, Alexander Sutin is developing a non-lethal weapon for protecting ports from underwater divers with malicious intentions -- an ac
|Contact: Jason S. Bardi|
American Institute of Physics