New Stretchable Battery Converts Sweat Into 3.9mW of Power
Researchers have developed a small, stretchable "battery" capable of converting perspiration into power for future wearable devices.
As our collective reliance on wearable devices increases, scientists are facing more pressure than ever before to develop innovative ways to generate and store power. You already have to charge your laptop, phone, tablet, smartwatch, headphones, and everything else you carry around; the last thing you want is another device that you have to plug in every night. That's why a team from Singapore's Nanyang Technological University created this small, stretchable "battery" that converts sweat into 3.9mW of power.
3.9mW is a very small amount of power. For comparison, your Apple Watch consumes about 100 times that amount when the screen is off and you aren't actually using it—far more when you are. But 3.9mW is still enough to perform useful work. The team that created this battery says that it is enough to power a simple temperature sensor and to transmit that sensor's data continuously over Bluetooth. That is for a version of the battery worn around the wrist by an individual peddling on a stationary bicycle to work up a good sweat.
A single "cell" of this battery is as small as 2 x 2 cm, or a bit smaller than a postage stamp. The battery, which contains special electrodes made of silver flakes, is both flexible and stretchable, making it comfortable to wear. When sweat, or any similar solution, coats the electrodes, the battery produces a small voltage. In the stationary bike testing, the team found that it produces about 4.2V. As low-power sensors and microcontroller become more common, this sweat-harvesting technology could be indispensable for powering wearable devices. Best of all, these "batteries" are affordable and easy to fabricate. They're durable enough to stand up to some abuse and cheap enough for disposable patches.
