From smart watches to external artificial kidneys, wearable technology is the new thing in science. Usually, these are powered by charging their battery’s when not in use. However, scientists have been trying to come up with more independent options for wearables.
Recently, researchers have turned to the human body to power one’s wearable devices. However, such “bioenergy harvesters” require the human to exert a lot of energy through vigorous exercise, a plan that is not very sustainable.
As sweat is so useful, a team of scientists from the University of California, San Diego, have designed a small collecting device that captures the sweat from fingertips. It wraps around the fingertip like a flexible bandage and contains a hydrogel that captures sweat during sleep. As the fingertips have the largest amount of sweat glands in the body, the harvester can collect a lot.
ROOZBEH GHAFFARI, A BIOMEDICAL ENGINEER AT NORTHWESTERN UNIVERSITY
“The ability to harvest tiny amounts of sweat from the fingertips is really unique,”
This sweat contains lactic acid, a by-product of anaerobic respiration. After the hydrogel collects the sweat, two foam electrodes break down its lactase using the lactase enzyme and take out its electrons. These electrons are then used by a third electrode containing platinum to convert oxygen into water. This flow of electrons between the electrodes helps the device generate 300 MJ/cm2 of energy in only 10 hours. Pressing the finger while wearing the harvester can generate a further 30 MJ per burst. To put that into perspective, a 10 hour sleep stint would be enough to power a wristwatch for a day. Quite a powerful little device indeed!
According to medical engineer Wei Gao from the California Institute of Technology (CALTECH):
“It allows the user to continuously harvest energy from the human body. From a power point of view, this makes wearable sensors more practical.”
In the future, the team plans to perfect the harvester’s sweat collection system and also create synergy with other harvesters. They also want to make sure that the hydrogel is long lasting. They believe that their device will work well to power future wearable devices.
Source: Science Magazine