Lightweight, Wearable Tech Efficiently Converts Body Heat to Electricity
September 14, 2016 | North Carolina State UniversityEstimated reading time: 2 minutes
Researchers at North Carolina State University have developed a new design for harvesting body heat and converting it into electricity for use in wearable electronics. The experimental prototypes are lightweight, conform to the shape of the body, and can generate far more electricity than previous lightweight heat harvesting technologies.
The researchers also identified the optimal site on the body for heat harvesting.
“Wearable thermoelectric generators (TEGs) generate electricity by making use of the temperature differential between your body and the ambient air,” says Daryoosh Vashaee, an associate professor of electrical and computer engineering at NC State and corresponding author of a paper on the work. “Previous approaches either made use of heat sinks – which are heavy, stiff and bulky – or were able to generate only one microwatt or less of power per centimeter squared (µW/cm2). Our technology generates up to 20 µW/cm2 and doesn’t use a heat sink, making it lighter and much more comfortable.”
The new design begins with a layer of thermally conductive material that rests on the skin and spreads out the heat. The conductive material is topped with a polymer layer that prevents the heat from dissipating through to the outside air. This forces the body heat to pass through a centrally-located TEG that is one cm2. Heat that is not converted into electricity passes through the TEG into an outer layer of thermally conductive material, which rapidly dissipates the heat. The entire system is thin – only 2 millimeters – and flexible.
“In this prototype, the TEG is only one centimeter squared, but we can easily make it larger, depending on a device’s power needs,” says Vashaee, who worked on the project as part of the National Science Foundation’s Nanosystems Engineering Research Center for Advanced Self-Powered Systems of Integrated Sensors and Technologies (ASSIST) at NC State.
The researchers also found that the upper arm was the optimal location for heat harvesting. While the skin temperature is higher around the wrist, the irregular contour of the wrist limited the surface area of contact between the TEG band and the skin. Meanwhile, wearing the band on the chest limited air flow – limiting heat dissipation – since the chest is normally covered by a shirt.
In addition, the researchers incorporated the TEG into T-shirts. The researchers found that the T-shirt TEGs were still capable of generating 6 µW/cm2 – or as much as 16 µW/cm2 if a person is running.
“T-shirt TEGs are certainly viable for powering wearable technologies, but they’re just not as efficient as the upper arm bands,” Vashaee says.
“The goal of ASSIST is to make wearable technologies that can be used for long-term health monitoring, such as devices that track heart health or monitor physical and environmental variables to predict and prevent asthma attacks,” he says.
“To do that, we want to make devices that don’t rely on batteries. And we think this design and prototype moves us much closer to making that a reality.”
Suggested Items
Real Time with… IPC APEX EXPO 2024: Ventec Discusses New Pro-bond Family of Advanced Products
05/01/2024 | Real Time with...IPC APEX EXPOChris Hanson, Ventec's Global Head of IMS Technology, outlines the launch of four pro-bond formulas that deliver an outstanding combination of low dissipation factor (Df) with a dielectric constant (Dk) range to maximize the design window for critical PCB parameters. As Chris points out, Pro-bond is designed for low-loss, high-speed applications, while thermal-bond dissipates heat from a component through the board to a heat sink.
Designing Electronics for High Thermal Loads
04/16/2024 | Akber Roy, Rush PCB Inc.Developing proactive thermal management strategies is important in the early stages of the PCB design cycle to minimize costly redesign iterations. Here, I delve into key aspects of electronic design that hold particular relevance for managing heat in electronic systems. Each of these considerations plays a pivotal role in enhancing the reliability and performance of the overall system.
IPC Design Competition: On Your Mark, Get Set, Go!
04/10/2024 | Andy Shaughnessy, Design007 MagazineI recently spoke with IPC’s Patrick Crawford, manager of design standards and related industry programs, and Kris Moyer, certified IPC master instructor, about this year’s IPC Design Competition. Now in its third year, the preliminary heat began in January, and the winners will compete in the final heat at IPC APEX EXPO in Anaheim.
Argonne Develops Plans to be Sure Nuclear Power Plants Stay Cool
04/05/2024 | BUSINESS WIREClimate scientists and nuclear science and engineering experts at the U.S. Department of Energy’s (DOE) Argonne National Laboratory are joining forces to develop a plan B for nuclear power in Richland, Washington.
Apollo Seiko Presents the Next Frontier in Non-Contact Soldering at 2024 IPC APEX EXPO
03/12/2024 | Apollo SeikoApollo Seiko, a leading innovator in soldering technology, is pleased to announce plans to showcase its latest advancements at Booth 1408 during the 2024 IPC APEX EXPO, taking place April 9-11, 2024 at the Anaheim Convention Center in California.