BACKGROUND: Inspired by the Namib Desert beetle that lives in one of the driest regions of the world, researchers at the Massachusetts Institute of Technology, in Cambridge, have developed a new material that can capture and control tiny amounts of water, just like the beetle does. Applications include its use for self-contaminating surfaces that could channel and collect harmful substances, such as germs, that could then be easily killed or deactivated. It could also be used for lab-on-a-chip diagnostics of DNA screening.
ABOUT DESERT BEETLES: The desert beetle has a built-in water collection system that allows it to survive where there is no water to be found, even when the humidity in the air is close to zero. This is important since normal condensation can't take place in the Namib Desert because the fog is too light. When fog blows across the surface of the beetle's back, water droplets begin to gather on top of the bumps on the insect's back These bumps attract water. They are also surrounded by waxy, water-repellent channels that pins the water drops on the beetle's back. Over time, the droplets get bigger, until they are large enough to roll down into the insect's mouth.
ABOUT THE MATERIAL: The new material developed by the MIT scientists can capture and control tiny amounts of water because its structure mimics that of the desert beetle. There are two surfaces, one water-repellant and another water attracting, that act together to separate and channel water drops. The researchers found they could control the surface texture of their material by repeatedly dipping glass or plastic substrates into charged polymer solutions. With every dip, another layer coats the surface, gradually making the material more porous so it easily attracts water. Adding silica nanoparticles -- particles only a few millions of a millimeter wide -- creates even more bumps to trap the collected water droplets. The final touch is a Teflon-like coating that makes the material super-water-repellent. And the scientists can create any pattern they want by adding more layers of charged polymers or nanoparticles in specific areas.
The Materials Research Society contributed to the information contained in the TV portion of this report.