Glass technology :

As the name suggests, smart glass, switchable glass, or privacy glass can be changed from clear to translucent with an electrical switch. Smart Glass is made with polymer dispersed liquid crystal (PDLC) technology. PDLC is the most commonly used Smart Glass technology for providing privacy on demand, however, you might be familiar with other smart technologies like electrochromic or thermochroic glass used primarily for reducing solar heat gain due to its grey-tinted properties. Smart glass in its natural state blocks light from passing through appearing translucent but when a voltage is applied its state becomes transparent allowing light to flood through the glass.  Some of the examples I’ve seen contain optical fibers and reflector elements that form thin layers directly under the surface enabling direct imaging into objects while at rest without interference by external lighting sources or clothing! The material also allows your smartphone screen to remain unaffected as it remains completely visible even after being dimmed down so no one will notice if you take pictures during dinner parties nor do they interfere with their night sleep process too!          A couple of companies such VivoLabs have created several types – which are available according to not only plastic vs metal finish:      Clear: This type uses silicon beads embedded in polypropylene sheets rather than plastic