Researchers at the Wyss Institute for Biologically Inspired Engineering have announced in a press release that they’ve developed a flexible material that can shed or retain moisture, and turn from opaque to transparent.
You can see how it works in the image below. The material is a liquid-repellent film that coats, and is infused in, an elastic porous backing. Normally the surface is flat and will shed water, but when the backing is stretched it changes the size of the pores, causing the surface to become rough and retain droplets.
In its normal state the material is transparent, but when stretched it becomes opaque. The material could be used to make a tent that blocks light on a dry and sunny day, and becomes transparent and water-repellent on a dim, rainy day.
The material may also be used in products as diverse as contact lenses and water pipes.
Researchers were inspired by the function of tears, which block materials from damaging the eye, and flush out these materials, yet remain transparent. Such inspiration is typical of work at the Wyss Institute, which looks to nature to find solutions to technological problems.