September 28, 2022

Scientists invent ultra-thin battery-like device that generates electricity from moisture in the air, perfect for health monitors

Professor Tan Swee Ching

Imagine being able to generate electricity by harnessing the humidity in the air around you with just everyday items like sea salt and a piece of cloth.

This is exactly what a team of researchers from Singapore has shown, after developing a water-repellent battery made of a thin layer of fabric, sea salt, carbon ink and a special water-absorbing gel. .

Approximately 0.3 millimeters thick, the Moisture Electricity Generating Device, or MEG, is built on the ability of different materials to generate electricity from interaction with moisture in the air. air, and could potentially adapt to a wide range of real-world applications, including wearable electronics such as health monitors, electronic skin sensors, and information storage devices.

Such devices have already been developed, but face major challenges in balancing and maintaining moisture content between where it shouldn’t be and where it needs to be.

Now, a research team led by Assistant Professor Tan Swee Ching from the Department of Materials Science and Engineering at the National University of Singapore has designed a new MEG device that can perpetually maintain a difference in water content and generate a electrical power for hundreds of hours.

The team’s MEG device consists of a thin layer of fabric coated with carbon nanoparticles. In their study, the team used a commercially available fabric made of wood pulp and polyester.

A region of the fabric is coated with a hygroscopic ionic hydrogel, and this region is known as the moist region. Made from sea salt, the special water-absorbing gel can absorb more than six times its original weight, and it is used to harvest moisture from the air.

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“Sea salt was chosen as the water-absorbing compound because of its non-toxic properties and its potential to provide a sustainable option for desalination plants to remove the sea salt and brine generated,” explained the professor. Deputy Tan.

The other end of the fabric is the dry region which does not contain a hygroscopic ionic hydrogel layer. This is to ensure that this region is kept dry and water is confined to the wet region.

After the MEG device is assembled, electricity is generated when sea salt ions are separated as water is absorbed in the wet region. The positively charged free ions are absorbed by the negatively charged carbon nanoparticles. This causes changes on the surface of the tissue, generating an electric field across it.

By using a unique design of wet and dry regions, the team showed that they could maintain power generation even when the wet region was saturated with water. After being left in an open humid environment for 30 days, water was still maintained in the humid region demonstrating the effectiveness of the device in maintaining electrical output.

“With this unique asymmetrical structure, the electrical performance of our MEG device is significantly improved over previous MEG technologies, making it possible to power many common electronic devices, such as health monitors and wearable electronics,” explained Tan.

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The MEG device has immediate applications due to its ease of scalability and commercially available raw materials. One of the most immediate applications is use as a portable power source for portable powering of electronics directly from ambient humidity.

By connecting three pieces of the energy-generating fabric together and placing them inside a 3D-printed case the size of a standard AA battery, the voltage of the assembled device was tested to reach 1.96 V, which is more than a commercial AA battery. battery about 1.5V, and enough to power small electronic devices like an alarm clock.

The scalability of the NUS invention, the convenience of obtaining commercially available raw materials as well as the low manufacturing cost of approximately SIN$0.15 per square meter make the MEG device suitable for mass production.

“Our device has excellent scalability at a low manufacturing cost. Compared to other MEG structures and devices, our invention is simpler and easier for scaling integrations and connections. We think it has great promise for commercialization,” Tan said.

CHARGE your friends with this awesome innovation…