Gizmorama - March 28, 2018
A new "water-harvesting device" has been proven successful when it extracted water from the dry, desert air Tempe, Arizona. This could be huge to humankind's survival in harsh climates. Let the harvest begin!
Learn about this and more interesting stories from the scientific community in today's issue.
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*-- New device can harvest water from arid desert air --*
In field tests, a new water-harvesting device successfully pulled water from the desert air in Tempe, Arizona. The new technology could allow humans to survive in some of the most inhospitable regions on Earth.
The new device -- described this week in the journal Nature -- is an improved version of the initial iteration, first described last year. When researchers at MIT first unveiled the device in 2017, skeptics voice a number of criticisms.
"All of the questions that were raised from last time were explicitly demonstrated in this paper," Evelyn Wang, a professor of mechanical engineering at MIT, said in a news release. "We've validated those points."
The device uses metal-organic frameworks, a unique material with an expansive internal surface area and molecule-trapping structures. Current water-harvesting devices require high humidity levels and are energy intensive.
The MOFs used in the device are made from water-attracting materials and painted black on top to encourage the absorption of sunlight. The water vapor is pulled into the material's tiny inner pores where the difference in temperature and concentration causes the vapor to condense and drip to the bottom.
Scientists field-tested their new device on the roof of an Arizona State University building -- "in a place that's representative of these arid areas, and showed that we can actually harvest the water, even in subzero dew points," Wang said.
The new device was powered only by sunlight. At present, the prototype is small, but researchers say it can easily be scaled up. Tests showed the device harvests a quarter-liter of water per day per kilogram of MOF material. Tests also showed the water is potable and free of impurities.
Because the device has no moving parts, scientists are confident that the technology is practical and can be deployed in the field.
By scaling up the technology and perfecting the metal-organic framework, scientists hope to triple the water output of their technology.
"We hope to have a system that's able to produce liters of water," Wang said. "We want to see water pouring out!"
*-- Earwig wings inspire scientists working on foldable device designs --*
When most people think of origami, they think of a swan or a butterfly. When a group of scientists in Switzerland think of origami, they think of an earwig.
Researchers at ETH Zurich say the wing of an earwig is the perfect example of origami's design principles.
When folded, the earwig's wing fits snuggly and compactly against its body, allowing it to tunnel into the soil. When it emerges from dirt, the wing expands, increasing its surface area by a factor of ten and allowing the insect to take flight.
What's more, the wing is so structurally sound that it doesn't require muscle activation for stability. It also folds into itself with a simple click -- a model of efficiency.
To better understand the wing's genius, scientists at ETH Zurich set out to recreate it. While traditional origami is limited to rigid, straight folds, the earwig's wing uses elastic folds.
The elastic folds provide either an extensional or rotational spring. Each fold's function is determined by the thickness of the wing's material, a unique biopolymer. Some joints combine extensional and rotational functions.
Scientists used a 3D printer to produce a simplified wing model. The first iteration of the 3D-printed wing featured four stiff plastic plates connected by elastic folds. Researchers then scaled up their model to more closely replicate the complexity of the earwig's wing.
Like the wing of the earwig, the new foldable 3D-printed wing is stable when open and folds into itself with a simple touch. The team of scientists described their experimentation and their wing prototype in a paper published this week in the journal Science.
Researchers believe the same design principles could be used to design foldable electronics, or to improve the functionality of tents and foldable maps.
"Once you've unfolded these things, it's often impossible to fold them back to their original shape," lead researcher Jakob Faber said in a news release. "If, on the other hand, they simply refolded automatically, this would save a lot of hassle."
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