Batteryless pacemaker uses a watch and a buffer circuit

Adrian Zurbuchen, a PhD candidate in the University of Bern's Cardiovascular Engineering Group, said: "Batteries are a limiting factor in today's medical implants. Once they reach a critically low energy level, physicians see themselves forced to replace a correctly functioning medical device in a surgical intervention. This is an unpleasant scenario, which increases costs and the risk of complications for patients." Zurbuchen's paper follows on from Professor Rolf Vogel's idea of using an automatic wristwatch mechanism to harvest the energy of heart motion. Zurbuchen said: "The heart seems to be a promising energy source because its contractions are repetitive and present for 24 hours a day, 7 days a week. Furthermore, automatic clockwork has a good reputation as a reliable technology to scavenge energy from motion." The first prototype is based on a commercially available automatic wristwatch. All unnecessary parts have been removed to reduce weight and size, with the device sutured directly on to the myocardium. To test the prototype, the researchers developed an electronic circuit to transform and store the signal in a small buffer. They then connected the system to a custom made cardiac pacemaker. Zurbuchen said: "We have shown that it is possible to pace the heart using the power of its own motion. The next step is to integrate the electronic circuit for energy storage and the custom made pacemaker into the harvesting device. This will eliminate the need for leads."