Gathering Water from Fog and Condensation.

• Position: MECHANICAL ENGINEERING

Humans can get by in the most basic of shelters and can scratch together a meal from the most humble of ingredients, but they cannot survive without clean water--and, in places where water is scarce, getting water to people requires feats of engineering and irrigation that can be cumbersome and expensive.

A possible solution is inspired by nature. "We thought, 'How can we gather water from the ambient air around us?'" says Bharat Bhushan, professor of mechanical engineering at Ohio State University, Columbus. "So, we looked to the things in nature that already do that: beetles, desert grasses, and cactus."

All three 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-repellent bumps on a beetle's back, then slide toward its mouth on the flat surface between the bumps. Desert grasses collect water at their tips, then channel the liquid toward their root systems via grooves in each blade. A cactus collects water on its barbed tips before guiding droplets down conical spines to the base of the plant.

Bhushan's team studied each of these living things and realized they could build a...