The prototype pacemaker developed by the Rice lab of electrical and computer engineering professor Aydin Babakhani harvests energy from an external battery pack and coil transmitted at 8 to 10GHz, storing the captured energy in a capacitor to provide power. The wireless operation avoids common problems with bleeding and infections from the leads and having to have minor surgery to replace a battery. It also allows multiple pacemakers to be fitted directly into different chambers of the heart.
A custom chip integrates a receiving antenna, AC-to-DC rectifier, power management unit and a pacing activation signal. This is combined with a capacitor and switch on a small circuit board.
A key element of the design is that the frequency of the signals produced by the pacemaker can be adjusted by increasing or decreasing power transmitted to the receiving antenna. The captured energy is stored until it reaches a predetermined threshold, and then releases the electrical charge, producing the required frequency.
“This technology brings into sharp focus the remarkable possibility of achieving the ‘Triple Crown’ of treatment of both the most common and most lethal cardiac arrhythmias: external powering, wireless pacing and — far and away most importantly — cardiac defibrillation that is not only painless but is actually imperceptible to the patient,” said Dr Mehdi Razavi, director of clinical arrhythmia research and innovation at the Texas Heart Institute and an associate professor at Baylor College of Medicine, who collaborated with Babakhani on the device.
The team successfully tested the device in a pig and demonstrated it could tune the animal’s heart rate from 100 to 172 beats per minute.
The team is further developing its technology in collaboration with Farshad Raissi, a cardiac electrophysiologist and assistant professor of medicine at UCSD, Rice’s Behnaam Aazhang, the J.S. Abercrombie Professor of Electrical and Computer Engineering, and Rice’s Joseph Cavallaro, professor of electrical and computer engineering and of computer science.