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Wearable microgrids: Powered by sweat

Researchers are capitalizing on human movement to power wearable devices.

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Quantumrun Foresight
January 4, 2023

Insight summary

Wearable technology applications include human health monitoring, robotics, human-machine interfacing, and more. The progress of these applications has led to increased research on wearables that can power themselves without additional devices.

Wearable microgrids context

Researchers are exploring how wearable devices can profit from a personalized microgrid of sweat energy to extend their capabilities. A wearable microgrid is a collection of energy-harvesting and storage components that allow electronics to function independently from batteries. The personal microgrid is controlled by a system for sensing, displaying, data transferring, and interface management. The concept of the wearable microgrid was derived from the “island-mode” version. This isolated microgrid comprises a small network of power generation units, hierarchical control systems, and loads that can operate independently from the primary power grid.

When developing wearable microgrids, researchers must consider the power rating and the type of application. The size of the energy harvester will be based on how much power is required by the application. For example, medical implantables are limited in size and space because they require large batteries. However, by using sweat power, implantables would have the potential to be smaller and more versatile.

Disruptive impact

In 2022, a team of nanoengineers from the University of San Diego, California, created a “wearable microgrid” that stores energy from sweat and movement, providing power for tiny electronics. The device comprises biofuel cells, triboelectric generators (nanogenerators), and supercapacitors. All parts are flexible and machine-washable, making it ideal for a shirt.

The group first identified sweat-harvesting devices in 2013, but the technology has since grown more powerful to accommodate small electronics. The microgrid could keep an LCD (liquid crystal display) wristwatch operating for 30 minutes during a 10-minute run and a 20-minute rest session. Unlike triboelectric generators, which provide electricity before the user can move, biofuel cells are activated by sweat.

All the parts are sewn into a shirt and connected by thin, flexible silver wires printed on the fabric and coated for insulation with waterproof material. If the shirt is not washed with detergent, the components will not break down through repeated bending, folding, crumpling, or soaking in water.

The biofuel cells are located inside the shirt and collect energy from sweat. Meanwhile, the triboelectric generators are placed near the waist and sides of the torso to convert motion into electricity. Both these components capture energy while the wearer is walking or running, after which supercapacitors on the outside of the shirt store energy temporarily to provide power for small electronics. Researchers are interested in further testing future designs to generate power when a person is inactive or stationary, such as sitting inside an office.

Applications of wearable microgrids

Some applications of wearable microgrids may include:

Smartwatches and Bluetooth earphones being charged during an exercise, jogging, or cycling session.
Medical wearables such as biochips being powered by the wearer’s movements or body heat.
Wireless charge clothing storing energy after being worn. This development may allow clothing to transmit power to personal electronics like smartphones and tablets.
Lower carbon emissions and lower energy consumption as people can charge their gadgets simultaneously while using them.
Increased research on other potential form factors of wearable microgrids, such as shoes, apparel, and other accessories like wristbands.