Amin Karami, an assistant professor of mechanical engineering at the University of Buffalo (
www.buffalo.edu), has come up with an idea for a piezoelectric-powered pacemaker that generates electricity in response to mechanical stress.
After working on two prototypes, he is talking to device makers about collaborating on a commercial product. Animal tests are scheduled to finish in two years; they will be followed by human tests.
Today’s typical pacemaker is a small flat device that fits easily in the palm of a hand, but Mr Karami believes that it could be smaller still. Only about 40% of a pacemaker consists of the pulse generator and related electronics, while about 60% is devoted to the battery; and because the battery eventually gives out, surgeons have to exchange the whole device every 7-10 years.
Doing away with the battery would do away with the inconvenience, medical risks and costs of those replacement surgeries.
Mr Karami’s first design is for an energy-harvesting module that could replace the batteries on a conventional pacemaker. His second idea takes the work a step further — to power a tiny lead-less pacemaker that nestles inside the heart itself.
To power a conventional pacemaker, Mr Karami designed a flat ceramic piezoelectric structure that oscillates in response to the vibrations in the chest cavity, which are generated with every heartbeat. He has tested his device with heartbeat rates ranging from 7 to 700 beats per min, and he found that there was more than enough power to keep a pacemaker running.
To design the piezoelectric power source for these tiny devices, he had to come up with a 3-D structure that would fit inside the lozenge-shaped device.
A lead-less pacemaker doesn’t require surgeons to open up the chest cavity, but can instead be delivered to the heart’s interior through a catheter in a vein.
Furthermore, getting rid of the wires also removes a potential point of failure (various cardiac leads have been recalled over the years when their insulation eroded or cracked).