Skip to Content

A Window that Doubles as a Mirror

And it can switch modes in record speed.
February 12, 2013

Diginfo reports that AIST has developed a light-controlling sheet that can render a window into a mirror in a matter of seconds. You may be surprised to learn that these switch-hitting mirror/windows are nothing new, in a sense; a division of AIST was actually working on something similar a year ago. But by paring the technology down to a miniscule sheet that affixes to glass–rather than having the technology be embedded in the glass itself–AIST has dramatically scaled back amount of time it takes to toggle between loads.

“For example,” explains a spokesman in the Diginfo video below, “windows in the Boeing 787 take 30 seconds to switch, but with our system, windows of the same size switch in five seconds.”

Why would you want something that can do double duty as a mirror and a window? Putting the glass in mirror mode also serves as a way of tinting the windows. Once you toggle into the reflective mode, there’s plenty of light outside that is no longer getting in. By shutting out sunlight, you can keep a building cooler on a hot summer day, and reduce use of air conditioning and concomitant costs.

The AIST spokesman walks viewers through the anatomy of the window: “On the back, there’s an acrylic sheet,” he explains, “and the new sheet we’ve developed is attached at the corners using tape. There’s inevitably a gap of 0.1 mm between the glass and the sheet. We fill the gap with hydrogen, which is produced by the electrolysis of water. In this way, the sheet can be switched from the mirror state to transparent.

There’s a word for this kind of class: “electrochromic” (it’s also known as smart glass, “magic” glass, or switchable glass). In TR’s own pages, we’ve actually been covering this topic for over a decade. See, for instance, “Electronic Windows Shades” and “Let (Some) Sun Shine In”–that last article dating back to 1998. Of course, technology is more easily conceived than executed, and incremental gains can be the difference between a mere concept and a market reality. Which is why AIST’s latest development, though small, is exciting.

Keep Reading

Most Popular

AV2.0 autonomous vehicles adapt to unknown road conditions concept
AV2.0 autonomous vehicles adapt to unknown road conditions concept

The big new idea for making self-driving cars that can go anywhere

The mainstream approach to driverless cars is slow and difficult. These startups think going all-in on AI will get there faster.

biomass with Charm mobile unit in background
biomass with Charm mobile unit in background

Inside Charm Industrial’s big bet on corn stalks for carbon removal

The startup used plant matter and bio-oil to sequester thousands of tons of carbon. The question now is how reliable, scalable, and economical this approach will prove.

AGI is just chatter for now concept
AGI is just chatter for now concept

The hype around DeepMind’s new AI model misses what’s actually cool about it

Some worry that the chatter about these tools is doing the whole field a disservice.

images created by Google Imagen
images created by Google Imagen

The dark secret behind those cute AI-generated animal images

Google Brain has revealed its own image-making AI, called Imagen. But don't expect to see anything that isn't wholesome.

Stay connected

Illustration by Rose WongIllustration by Rose Wong

Get the latest updates from
MIT Technology Review

Discover special offers, top stories, upcoming events, and more.

Thank you for submitting your email!

Explore more newsletters

It looks like something went wrong.

We’re having trouble saving your preferences. Try refreshing this page and updating them one more time. If you continue to get this message, reach out to us at customer-service@technologyreview.com with a list of newsletters you’d like to receive.