Heart Beats May Soon Power Pacemakers, Implanted Defibrillators
Would save many seniors worry of surgical battery replacement
March 5, 2012 – For thousands of senior citizens a cardiac pacemaker and an implanted defibrillator are wonderful
inventions, but there is the worry about batteries to keep them going and the stress of having them surgically replaced. Scientist think,
however, they are making progress on a solution – a way of using vibrations from heartbeats to power the devices.
Engineering researchers at the University of Michigan designed a device that harvests energy from the reverberation of
heartbeats through the chest and converts it to electricity to run a pacemaker or an implanted defibrillator.
These mini-medical machines send electrical signals to the heart to keep it beating in a healthy rhythm. By taking the
place of the batteries that power them today, the new energy harvester could save patients from repeated surgeries. That's the only way today
to replace the batteries, which last five to 10 years.
Large study in
New England Journal of Medicine says cardiac resynchronization
therapy can boost a fading heart beat - new hope for many senior
citizens - Nov. 14, 2010
"The idea is to use ambient vibrations that are typically wasted and convert them to electrical energy," said Amin Karami,
a research fellow in the U-M Department of Aerospace Engineering. "If you put your hand on top of your heart, you can feel these vibrations
all over your torso."
The researchers haven't built a prototype yet, but they've made detailed blueprints and run simulations demonstrating
that the concept would work.
Here's how: A hundredth-of-an-inch thin slice of a special "piezoelectric" ceramic material would essentially catch
heartbeat vibrations and briefly expand in response. Piezoelectric materials' claim to fame is that they can convert mechanical stress (which
causes them to expand) into an electric voltage.
Karami and his colleague Daniel Inman, chair of Aerospace Engineering at U-M, have precisely engineered the ceramic layer
to a shape that can harvest vibrations across a broad range of frequencies. They also incorporated magnets, whose additional force field can
drastically boost the electric signal that results from the vibrations.
The new device could generate 10 microwatts of power, which is about eight times the amount a pacemaker needs to operate,
Karami said. It always generates more energy than the pacemaker requires, and it performs at heart rates from 7 to 700 beats per minute.
That's well below and above the normal range.
Karami and Inman originally designed the harvester for light unmanned airplanes, where it could generate power from wing
vibrations.
A paper on the research, titled "Powering pacemakers from heartbeat vibrations using linear and nonlinear energy
harvesters," is published in the current print edition of Applied Physics Letters.
The research is funded by the National Institute of Standards and Technology and the Institute for Critical Technology
and Applied Science at Virginia Tech.
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March 5, 2012 – For thousands of senior citizens a cardiac pacemaker and an implanted defibrillator are wonderful
inventions, but there is the worry about batteries to keep them going and the stress of having them surgically replaced. Scientist think,
however, they are making progress on a solution – a way of using vibrations from heartbeats to power the devices.