As anyone owning an Apple Watch will tell you, it can be a hassle to have to recharge the device’s battery to maintain its capabilities. Yet there’s a whole future of small and highly capable body monitoring technologies coming our way that will need a power source that’s better than conventional batteries.
At North Carolina State University researchers have been working on perfecting thermoelectric generators to make them powerful enough to energize all kinds of body-worm devices.
Thermoelectric generators rely on a temperature gradient between one side of their surface and another, in this case the skin of the body and the air around. In order to quickly dissipate the heat coming from the body and cool the side facing the air previous designs relied on metallic heat sinks, the kind that sit over the CPU inside most computers. But this makes the generators heavy, bulky, and uncomfortable to wear.
The NC State team instead used a thermally conductive material to channel the heat into a thermoelectric generator in the center of the patch-like device, producing more energy this way than spreading the generator over the entire body of the generator.
Their approach is able to generate up to 20 µW of electricity for every square centimeter of the patch, so it can be scaled to provide the necessary power depending on the application.
The team also identified that the upper arm may be the best location to harvest heat energy as it’s easily accessible, produces a good deal of heat, is fairly smooth, and is often left exposed to ambient air.
Study in journal Applied Energy: Wearable thermoelectric generators for human body heat harvesting…
Source: NC State…
