Scientists have developed a new battery-free pacemaker that takes energy from heartbeats, with pigs used to successfully test the devices.
A revolutionary battery-free pacemaker that harvests energy from heartbeats has been successfully tested in pigs.
The device, designed to correct an irregular heart rhythm, points the way forward to medical implants free of bulky power packs.
It works using a hi-tech "energy harvester" wrapped around the heart that generates electricity from movement.
With each beat of the heart, more electricity is produced to power the pacemaker.
Pigs were used in the tests, described in the journal Nature Communications, because their hearts are about the same size as those of humans.
The reciprocal way it operates within the body led to the device being dubbed a "symbiotic cardiac pacemaker" (SCP).
The team of American and Chinese scientists, led by Dr Zhong Lin Wang from the Georgia Institute of Technology in the US, wrote in the journal: "Millions of patients rely on implantable medical electronic devices (IMEDs) due to powerful diagnosis and treatment capabilities.
"For decades... circuits of IMEDs have evolved into ultra-lower power consumption, miniaturised and flexible devices under the synergy between academia and industry.
"However, batteries of IMEDs are generally bulky, rigid, and have short lifetimes... Power source has impeded the progress of IMEDs."
The tests showed that the harvested energy was higher than that needed for a human pacemaker.
However, it could be some years before symbiotic pacemakers are ready to be implanted safely into human patients.
British expert Tim Chico, professor of cardiovascular medicine at the University of Sheffield, said: "The study results are very encouraging but there is a lot of work to be done before it might be used in humans.
"The energy harvest device needed to be inserted around the heart in open heart surgery, which is a lot more invasive than is needed for current pacemakers and would greatly limit who could have this. However, the device could use movement from other muscles rather than the heart, so this should not be a problem.
"People who need the pacemaker to work a lot or all of the time, or to deliver defibrillation, use a lot more electricity and so it is important that any self-powering device has enough stored energy for these situations."