Imagine changing the windows in your home from transparent to opaque at the flip of a switch, allowing you to keep your home warm and well-lit, or dark and cool, depending on your preference. That ability might be here sooner than you think - researchers at the University of Cambridge have developed a new smart glass that allows users to do just that. Smart glass like this isn't new, but earlier versions have required a constant stream of electric power. This one, on the other hand, only requires energy when you flip the switch. This new smart glass uses less energy because of how it becomes opaque: liquid crystals. Popular Mechanics explains, here:
"When you run a voltage through a panel full of LCD crystals, also know as nematic crystals, it produces an electric field. Normally, these crystals all point every which way, but when the crystals are in this field, they rearrange themselves so that they all face the same direction. In LCD TVs, this sort of electric manipulation lets crystals form a filter the colors the light behind them, depending on how the field has them pointing. With the smectic liquid crystals used in this new smart glass, an electrical voltage has a different result. Not only do the crystals line up in the same direction when there's a field, they also arrange in stacked layers. So instead of just forming filters that affects light as it flows through—likes single sheets of crystal—these stacks can be coerced to criss-cross in such a way that they actually become opaque."
The change occurs in the blink of an eye and, most importantly, the crystals stay that way until you flip the switch to change them. This limited need for energy to what makes the new smart glass so compelling; other smart glass options have worked more like lightbulbs, needing power when to stay on, but none to stay off. This smart glass, termed smectic windows, acts more like blinds, requiring energy to open or close, but none in the interim. Smectic windows could just be cost-effective enough to become widely used in everything from energy-efficient buildings to a sunroof in a car.
Where would you want this kind of smart glass?