Self-assembling nanoparticles turn this window into a mirror and back

Chances are that you’re familiar with one-way glass, which looks like a mirror from one side, but is completely transparent from the other. Researchers from the United Kingdom’s Imperial College London have taken this tech to the next level, courtesy of a material that’s capable of transitioning between a mirror and a window with the press of a button. And all it requires is a layer of tiny nanoparticles, an electrical current, and a whole lot of cutting-edge chemistry.

“Put simply, we have developed a system which can change from being transparent to a mirror and back to being transparent by applying an electrical voltage,” Anthony Kucernak, a professor in Imperial’s Department of Chemistry, told Digital Trends. “This voltage drives nanoparticles to an interface, where they congregate and form a mirror. When we switch the system to a different voltage, the particles move away from the interface and the mirror disappears.”

To make their electronically switchable windows, Imperial College researchers created a layer of evenly spaced gold nanoparticles, thousands of times tinier than the width of a single human hair. This layer is formed when gold nanoparticles self-assemble between two liquids which don’t mix. These nanoparticles are then made to change configuration through the use of a small voltage. When they’re closer together, they act as a mirror; when further away, they offer window-like transparency.

Imperial College London isn’t the first place to explore this territory, but the researchers’ work is unusual in the sense that it describes a reversible process, capable of transitioning back and forth between mirror and transparent surfaces as many times as required. As to what’s next, Anthony Kucernak says that, “We are considering the possibility of commercialization. Our future work is looking into ways of increasing the speed of response.”

It’s definitely nifty tech — and something we’d love to see in the smart home of the future, alongside similar research into dimmable windows. We guess that in this case you just need to remember which mirrors it’s safe to undress in front of!

A paper describing the work, titled “Electrotuneable Nanoplasmonic Liquid Mirror,” was recently published in the journal Nature Materials.