Heart-powered pacemaker could one day eliminate battery-replacement surgery

Mar 02, 2012

A new power scheme for cardiac pacemakers turns to an unlikely source: vibrations from heartbeats themselves.

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 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.

"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 . "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 (which causes them to expand) into an .

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 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.

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More information: Paper: apl.aip.org/resource/1/applab/v100/i4/p042901_s1?bypassSSO=1

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DGBEACH
2 / 5 (1) Mar 03, 2012
"By taking the place of the batteries that power them today, the new energy harvester could save patients from repeated surgeries."
but...
"It always generates more energy than the pacemaker requires, and it performs at heart rates from 7 to 700 beats per minute"

Did I miss something...if it only performs above 7 BPM but has NO BATTERY BACKUP...then the poor guy who gets this thing is pretty much toast if his heart stops! ???
antialias_physorg
not rated yet Mar 03, 2012
The idea is to harvesd the energy, store it, and use it when it's neded (i.e. when the heart stops or it goes into fibrillation) - not to harvest it while the patient is in trouble.

Pacemaker don't need to work all the time. They are adaptive enough to recognize when 'input' is needed. This has, to date, been the strategy for saving battery life.
(If pacemakers needed to work with every beat then you'd probably be in line for a heart transplant or an artificial pump)
dschlink
not rated yet Mar 03, 2012
Energy storage will probably shift to small ultra-capacitors, which can easily store enough energy for several minutes of operation; but do not require replacement.

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