How do “tint-able” windows on airplanes work?


I was on a long flight this evening and the windows at each seat had a button which allowed the passenger to select how tinted they wanted the window to be. How does it work?

In: 2

Avgeek here (and first time answering ELI5). You probably set foot on a Boeing 787! One of its cool interior features is its electro-(electricity) chromatic (light) windows!

As the name suggests, electricity is used to change the opacity of a gel which is applied to the window. By default the window looks completely transparent. An electric current would activate (make opaque) the gel, and the lack of it returns it to its normal state.

Passengers can control the opacity by changing the amount of electric current applied.

~~Rear-view mirrors of some cars use this principle too.~~

Edit as the first time around i got it backwards. I believe that my initial explanation was used for a different type of electrochemical gel.