One of the principal flaws with wearable electronics, such as fitness devices, smart wristwatches, and heart-rate monitors, is that they need batteries for power. It makes the tech bulky.
That bulk isn't conducive to consumers' acceptance of wearable electronics. People don't like it.
But you need power, and quite a lot of it. For wearables to be truly useful, they need to connect in some way to other devices—like smartphones and the Internet—for number-crunching and display.
That connectivity, though, is power-hungry. It takes a significant burst of power to broadcast data, particularly over Wi-Fi, and over distance.
Designers' choices thus far have been heavy and voluminous batteries, or puny ones that need frequent re-charging or replacement.
However, some scientists reckon they've come up with a new solution: get the garments themselves to create the power.
Researchers at the Massachusetts Institute of Technology and the University of British Columbia say that because you're only interested in short bursts of power, it's possible to use supercapacitors to supplement or replace batteries.
And you should be able to create supercapacitors in strong, thin yarns, which can be woven directly into the wearable textiles.
Supercapacitors are an alternative to battery technology. They use a kind of static charge instead of a chemical reaction. Applying voltage charges the capacitor.
One big advantage over batteries in general is that supercapacitors can handle frequent charging and discharging in short bursts, which is just what's needed in wearable tech.
A downside has been that capacitors have been heavy—heavier than batteries sometimes.
The scientists from the two universities suggest using nanowire yarns made out of the element niobium. Carbon nanotubes have been used as well, but the researchers say niobium is better.
Niobium yarns have higher capacitance and energy per volume "and are stronger and 100-times more conductive than similarly spun carbon and graphene yarns," one of the scientists, Seyed M. Mirvakili said in the associated research article published by the American Chemical Society's (ACS) Applied Materials and Interfaces journal.
Alternatives like "carbon nanotubes and graphene have shown promising results, but they suffer from relatively low electrical conductivity," Mirvakili says.
Batteries with capacitors
The team says one good option could be to combine batteries with the yarn-based capacitors. The battery would be used for the long-term low-power functions and the capacitor for the bursts of high power for communications.
That way, the tech either increases the device's range or reduces size, the team said in a separate MIT article published by Science Daily.
"Consumers are very sensitive to the size of wearable devices," Ian W. Hunter of MIT said in the article. This should solve that. The highly-flexible wires are about one-thousandth of the width of a human hair.
And an added bonus is that niobium has a high melting point of almost 2,500 degrees Celsius, so we could see it in future Internet-connected Personal Protective Equipment applications too.
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