Invention turns fog into drinking water

A student has developed a bug-inspired fog-harvesting device for people who don't have access to clean water.
Written by Tuan Nguyen, Contributor

One of the strange conundrums of fog is that while it's comprised of clean water, it's way too dispersed to be of use to anyone.

However, there's one creature that's able to drink fog -- literally. The Namib Beetle, native to the Namib Desert in Africa, does this by collecting water droplets on its bumpy back, then lets the moisture roll down into its mouth.

Now a student at MIT named Shreerang Chhatre has developed a bug-inspired fog-harvesting device for people living in regions who don't have access to clean water. This is a problem that affects an estimated nearly 900 million people worldwide, according to the World Health Organization and UNICEF.

“As a middle-class person, I think it’s terrible that the poor have to spend hours a day walking just to obtain a basic necessity,” Chhatre says.

He wanted to model his device after the Namib beetle's shell because it relies entirely on the very simple principle of shape. For instance, the bumps attract water, while the troughs repel it. So when enough droplets accumulate on the bumps, it washes through the troughs (without being absorbed) and into the beetle’s mouth.

(To see more inventions that help developing regions check out the humanitarian tech image gallery.)

But to build an effective fog harvesters for people, the researchers used a mesh rather than a solid surface like a beetle’s shell. This is because early experiments showed that a completely impermeable object creates wind currents that divert water droplets away from it.

“We tried to replicate what the beetle has, but found this kind of open permeable surface is better,” Chhatre says. “The beetle only needs to drink a few micro-liters of water. We want to capture as large a quantity as possible.”

In field tests, the device captured one liter of water per square meter of mesh over the course of a day. His research team are conducting further tests to improve the water collecting capacity of current mesh designs.

But even so, one of the biggest challenges would be to develop a product that would be affordable enough to be available to the people who need it most.

“My consumer has little monetary power,” says Chhatre. “This is still a very open problem. It’s a work in progress.”

(via MIT)

Image: Patrick Gillooly/MIT

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