Battery-less device powers a pacemaker using heartbeats
By Ben Coxworth
September 2, 2014
Although cardiac pacemakers have saved countless lives, they do have at least one shortcoming – like other electronic devices, their batteries wear out. When this happens, of course, surgery is required in order to replace the pacemaker. While some researchers are looking into ideas such as drawing power from blood sugar, Swiss scientists from the University of Bern have taken another approach. They’ve developed a wristwatch-inspired device that can power a pacemaker via the beating of the patient’s own heart.
Bern cardiologist Prof. Rolf Vogel first came up with the idea four years ago, and it has been in development ever since. The resulting prototype device wasn’t just inspired by an auto-winding wristwatch, but actually incorporates the mechanism of a commercially-available model.
Such watches rely on the user’s arm movements to wind a mechanical spring. Once that spring is fully wound, it then unwinds to power a micro-generator inside the watch.
In the case of the Bern device, it’s sutured onto the heart’s myocardial muscle instead of being worn on the wrist, and its spring is wound by heart contractions instead of arm movements. When that spring unwinds, the resulting energy is buffered in a capacitor. That capacitor then powers a pacemaker, to which it is electrically wired.
According to the research team, the system has demonstrated a mean output power of 52 microwatts when implanted in a live 60-kg (132-lb) pig – that’s more than enough for most modern pacemakers, which consume about 10 microwatts.
They now hope to further miniaturize the technology, make it more sensitive to the motion of the heart, and build both its energy-harvesting and capacitor functions into a pacemaker. This all-in-one setup would do away with the need for electrical leads, which can fail in conventional pacemakers.
The research was presented this Sunday at the ESC (European Society of Cardiology) Congress, by PhD candidate and team member Adrian Zurbuchen.
A similar device is being developed at the University of Michigan.