UD engineers are building ‘smart glass’ that could make window blinds obsolete

Someday, the average home will be outfitted with smart glass windows — eco-friendly panels that can go from transparent to opaque, making inefficient (and flat-out dangerous) window blinds a thing of the past.

Keith Goossen, associate professor of electrical and computer engineering at the University of Delaware, and Daniel Wolfe, who earned a doctoral degree from UD in 2017, have been perfecting “smart glass” technology, including making it more affordable. Their smart glass creation is both more transparent than previous smart glass, and it’s about ten times less expensive to produce, Julie Stewart of UDaily reports:

The principles behind this smart glass technology are surprisingly simple. It starts with two sheets of plastic separated by a thin cavity. The plastic contains tiny cube-shaped structures that make the material retroreflective, meaning that it bounces light back to its source, like a bicycle reflector does.

Then the chamber is filled with a fluid called methyl salicylate—an inexpensive wintergreen extract that happens to be the active ingredient in some over-the-counter pain relief creams. This liquid has optical properties, or interaction with visible light, that match the optical properties of the retroreflective plastic. When combined, the light can pass through, and the system becomes transparent. This is called refractive index matching.

Goossen’s smart glass system can switch from transparent to reflective a thousand times without degrading, as shown in a paper published late last year in the journal Optics Express.

Goossen shared his latest smart glass prototype at the SPIE Smart Structures + Nondestructive Evaluation conference in Denver on March 5.