Why is this important? - Liquid crystals: living cells and flat screen TVs
Look around you. How many things do you think contain liquid crystals?
You may be surprised by the answer. Liquid crystals are a multi-billion dollar industry and these fascinating materials are used as displays in a range of products including flat screen TVs, mobile phones, and laptops.
The special properties of liquid crystals - having their molecules arranged in order, but still being able to flow like a liquid - means that they have specific optical effects, which are perfect for showing images in electronic devices.
In liquid crystal displays, an electric field changes the orientation of the liquid crystal molecules. This affects the polarisation of the light waves that are transmitted by the liquid crystal. Red, green and blue colour filters can be placed on each pixel of the display, and colour images are produced, like in LCD TVs or laptops, in contrast to the simple black and white displays of pocket calculators.
Where else can you see liquid crystals?
Liquid crystals can form different types of modern materials. There is a polymer called Kevlar® which is made from the liquid crystalline state, giving a strong fibre - as strong as steel at only 1/5th of the weight! This type of polymer is used to create bulletproof vests, firemen’s protective gear, sails on boats and the ropes used in climbing.
Special sheets made from liquid crystals are also used in industry to look for hot spots in machinery (which might be a signal that an electrical device has failed), to map heat flow and to measure stress distribution patterns. This is because the liquid crystals will change colour with temperature, and the temperature depends on material failure or infections or tumours.
In your home, liquid crystals are not only in electronic devices, they are also in your washing up bowl! Liquid crystals are in soap and detergent. The slimey stuff that collects in the bottom of soap dishes is soap in a liquid crystal phase.
Liquid crystals and life
Liquid crystals are also fundamentally important to life. DNA and cell membranes have liquid crystal phases. Our brains are around 70% liquid crystal, and liquid crystals are also found in muscles, the amazing iridescent colours of some insects, and also slug slime!
Science for you to try!
Go to main page of Teacher's Resource - Liquid crystals: living cells and flat screen TVs
View this information in printable format.