Switchable Privacy Glass

[SouthsideX]

I have read about 'UMU' Switchable Privacy Glass - which can be changed from a solid colour to a clear (see through) glass by feeding an electrical current through it - How does this work and/or how is this made?

[woolley]

UMU glass is made by laminating a liquid crystal interlayer sheet between two sheets of glass. In clear mode, an electrical current is passed through the interlayer which aligns the microscopic crystals along a number of parallel axes, allowing you to see through it. When the current is switched off, the crystals scatter into a random formation which prevents you seeing through it. The liquid crystal interlayer is similar to the one used in calculators, watches, clocks, and laptop computers. The main difference is the method of control. In these electronic devices, the graphics are made by controlling individual pixels within the display area. UMU works by controlling the whole panel as one pixel.