In the last decade, wearable electronics, particularly those designed for healthcare, have gained significant popularity. However, researchers are still working on the best ways to power them.
Traditional batteries are currently the most common solution, but they often need more flexibility and last only a short time with continuous use.
Wireless power transfer techniques provide an alternative solution, but these systems have limited range and portability.
As a solution, Binghamton University Professor Seokheun “Sean” Choi, Assistant Professor Anwar Elhadad, and PhD student Yang “Lexi” Gao have developed a new method to pull moisture from the air and turn that water into electricity.
Electricity generation through air
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In a recently published paper in the journal Small, the Binghamton team outlined their paper-based wearable device that would provide sustained high-efficiency power output through moisture capture.
“Wearable electronics will use energy-harvesting techniques in the future, but right now, the techniques are very irregular in time, random in location and inefficiently converted,” Choi said.
“I was interested in this topic because the moisture in our air is ubiquitous, and I realized that energy harvesting from moisture is very easy.
Adapting the knowledge that Choi’s Bioelectronics and Microsystems Lab has gained about biobatteries over the past 15 years, the generator uses bacterial spores as the “functional group” that breaks down the water molecules into positive and negative ions.
The paper’s capillaries absorb the spores, creating a gradient with more positive ions on top than on the bottom. That imbalance leads to an electric charge.
Adding a Janus paper layer that is hydrophobic on one side and hydrophilic on the other enhances moisture absorption.
This layer draws in water molecules and keeps them inside the device until they are processed.
Paper-based wearable device
The research continues Choi’s pursuit of papertronics, which involves making devices entirely out of paper that are flexible, wearable, scalable, and disposable without harming the environment.
He sees the moist-electric generator as revolutionary for low-power sensors, drug delivery, or electrical stimulation.
Potential improvements and refinements include increasing power output, developing a method for energy storage, and integrating it with other energy-harvesting techniques.
Choi also hopes to shrink the device to the same scale as micro-electromechanical systems (MEMS).
“The size of one device is too big for me. I’m a MEMS guy!” he said.
“By decreasing each unit and connecting more cells within a small footprint, we can improve the power density significantly. Also, because we use paper, we can try many other ideas, including origami techniques.”
While other researchers are developing long-term wearable devices, Choi’s instinct is to go the opposite direction by focusing on disposable devices that won’t clutter up landfills with electronic waste.
“I don’t want to wear something all day for four months,” he said.
“I want to use it for a short time and then throw it away — so in that way, paper is the best.”
However, this is not the first time a device has been made that generates electricity from moisture in the air.
In May, researchers at the University of New South Wales (UNSW) in Australia successfully engineered protein filaments produced by bacteria so that they can conduct electricity and even harness it using moisture from the air.
A university press release said this interdisciplinary research, comprising protein engineering and nanoelectronics, could one day help scientists develop ‘green electronics.’
According to Interesting Engineering