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Collecting clean water from air, inspired by desert life (DECEMBER 26, 2018 )

Titre : Collecting clean water from air, inspired by desert life

Humans can get by in the most basic of shelters, can scratch together a meal from the most humble of ingredients. But we can’t survive without clean water. And in places where water is scarce—the world’s deserts, for example—getting water to people requires feats of engineering and irrigation that can be cumbersome and expensive

The cactus, beetle and desert grasses all collect water condensed from nighttime fog, gathering droplets from the air and filtering them to roots or reservoirs, providing enough hydration to survive.

Drops of water collect on wax-free, water-repellant bumps on a beetle’s back, then slide toward the beetle’s mouth on the flat surface between the bumps. Desert grasses collect water at their tips, then channel the water toward their root systems via channels in each blade. A cactus collects water on its barbed tips before guiding droplets down conical spines to the base of the plant. They started studying the ways by which different surfaces might collect water, and which surfaces might be the most efficient. Using 3-D printers, they built surfaces with bumps and barbs, then created enclosed, foggy environments using a commercial humidifier to see which system gathered the most water.

They learned that conical shapes gather more water than do cylindrical shapes—"which made sense, given what we know about the cactus," Bhushan said. The reason that happens, he said, is because of a physics phenomenon called the Laplace pressure gradient. Water gathers at the tip of the cone, then flows down the cone’s slope to the bottom, where a reservoir is waiting.

Source  : Laura Arenschield, The Ohio State University

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Page publiée le 29 juin 2021