A deterrent to long-term wearable use is having to remove devices to charge overnight. But what if the sweat you naturally produce could keep devices like smartwatches powered 24/7?
A team of engineers based out of the University of California San Diego have developed stretchable fuel cells that can extract energy from sweat and are capable of powering electronics.
The cells, which researchers say generate 10-times more power per surface area than any existing wearable biofuel cells, are currently being tested to power things such as LEDs and Bluetooth radios. But over time they could power “a range of wearable devices,” including much more power-intense ones, such as smartwatches.
This would be a huge win for the consumer-based health and fitness wearables market, where people are using devices to track sweat-inducing activities such as hiking, running and cycling, but also want to use the sleep tracking functionalities without having to remove devices at night.
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To test the epidermal biofuel cells, researchers connected them to a custom-made circuit board and demonstrated how the device was able to power an LED for four minutes while a person exercised on a stationary bike.
The cells are equipped with an enzyme that oxidizes the lactic acid in human sweat to generate a current, thus turning sweat into a source of power. The circuit board acts as a converter that ensures a consistent power source even as sweat production varies
As researchers design more powerful biofuel charging cells, they’ll be able to increase the energy density produced by each cell to charge more energy-intense devices. They’re also looking at ways to store the energy produced while the concentration of lactate in the sweat is higher, so that they can release it gradually and power devices for a longer period of time.
Generating high power density under practical conditions and powering conventional energy-intense electronic devices represents “a major step forward in the field of soft, stretchable, wearable energy harvesting devices,” the engineers said.
This research comes as consumer technology industry tracker IDC forecasts that wrist-worn devices, such as smartwatches and fitness trackers, will continue to grow in popularity.
According to its most recent quarterly report, IDC forecasts vendors will ship 121.7 million wearable devices this year, marking a 16.6% year-over-year increase from 2016. That pace of growth is expected to be maintained through 2021 with shipments reaching 229.5 million units.