Patients could one day be fitted with pacemakers that run on body heat.
Pacemakers have been used for 40 years
Scientists at Biophan Technologies in New York are developing a "biothermal battery" that turns the body's own heat into electricity.
According to New Scientist magazine, the device could be used to power small medical implants like pacemakers.
If successful, it could enable patients with pacemakers and other implants to go much longer without having to undergo surgery to replace batteries.
At the moment, most patients who have been fitted with pacemakers need to have surgery to replace the battery that powers the device every few years.
The scientists who are developing this new type of battery say it is designed to last as long as 30 years.
The battery uses thermoelectric materials, which are special types of semiconductors that produce electricity when one side of the material is heated and the other is cooled.
These materials have been used to generate electricity on spacecraft that are too far away from the sun for solar cells to operate.
Recent advances in nanotechnology have now made it possible to use these materials to power small devices, like medical implants.
"With the nanotechnology revolution under way, the ability to now put thousands and thousands of these small semi-conductor nodes that convert heat to electricity in the small space, perhaps the size of one or two postage stamps, has become feasible," said Michael Weiner, the company's chief executive.
Scientists believe the battery can be implanted under the skin, where there can be a
temperature difference of up to five degrees Celsius.
The company says the device could be used to power pacemakers and other devices, such as the tiny neurotransmitters that are implanted in the brains of some people with Parkinson's disease.
The British Heart Foundation backed the project.
"More than 26,000 people in the UK had a pacemaker implanted last year," said Dr Tim Bowker, its associate medical director.
"They can transform the treatment and lives of people with a slow or weakened heart beat, by helping to control the heart beat at an appropriate rate.
"However, the pacemaker battery must be replaced every few years by a surgical procedure.
"We would welcome any advance in technology which could prolong the pacemaker's battery life, and which was safe and acceptable to the patient.
"If the battery could be replaced less frequently, patients would need fewer surgical procedures, which are both stressful and carry a risk of infection."