Originally Published MPMN January/February 2002

INDUSTRY NEWS

Energy-Efficient Battery Runs on Body Heat

A wafer-thin, fingernail-sized thermoelectric generator converts low-gradient body-heat flow into electrical power that can be used to run embedded or attachable medical devices. The ½ x ½-in. ceramic battery does not contain any chemicals and requires no replenishment, giving it potential applications in wireless medical equipment.

Peter Zhou is vice president and chief scientist at Applied Digital Solutions Inc. (ADS; Palm Beach, FL; www.adsx.com), the company that developed the battery. He explains that while the technology behind the device is not itself new, the fact that it is miniaturized to this scale is a breakthrough. "The technology underlying the generator has its roots in space exploration, where satellite applications require long-lived batteries in a small package," says Zhou, a physicist who was educated at the fabled Max Planck Institute in Stuttgart, Germany.

"Our new approach has [produced] a fingernail-sized battery that generates 1.5 V of electricity at 10 µA, based on a 5°–10°F temperature gradient," he says, adding that the company will soon be able to produce a 3-V model that uses the same technique.

ADS originally developed the battery as a component for the company's Digital Angel technology platform. The Digital Angel product series is described by the company as a "combination of advanced biosensor technology and Web-enabled wireless telecommunications linked to Global Positioning Systems (GPS)." The products are based on portable devices that monitor patient vital signs and transmit these data, along with a GPS signal, to remote monitoring centers. According to Zhou, the miniature battery created so much interest that the company decided to introduce it as a stand-alone product.

The continuous body-heat battery has a range of applications in implantable and attachable medical devices, as well as wristwatches. Its small size makes it an attractive power source in such products. It is also a solid-state capacitor, so it poses no danger of contamination or harmful interaction with the body. And its dependence on body heat gives it the further advantage of reliability, since it effectively eliminates the need to periodically replace power sources. Or, as Zhou puts it: "As long as you're alive, it's always on."

Because of its low power output, the battery is best suited for noncontinuous operation in devices such as alarms, where energy can be stored and released intermittently. Nerve stimulation and other applications relying on "standby" devices are also expected to benefit from the technology.

ADS is interested in licensing the battery to OEMs and is already in discussion with medical manufacturers. Richard Sullivan, the company's chairman and CEO, says, "We're looking forward to working with the medical community, battery manufacturers, and other potential partners."

Benjamin Lichtman

Copyright ©2002 Medical Product Manufacturing News