A number of organic compounds and biological tissues behave as liquid crystals. Important practical applications are given below;
Liquid crystals are used in the display of electrical devices such as digital watches, calculators and computers. These liquid crystals devices take advantage of the fact that the weak bonds hold molecules together in a liquid crystal are easily affected by changes in pressure, temperature or electromagnetic fields.
The temperature dependent variation in the colour of cholesteric liquid crystals had led to the use of these substances in measurement of temperature and temperature gradients.
Cholesteric liquid-crystal substances, when applied to the surface of the skin, have been used to locate the veins, arteries, infections, tumours and the fetal placenta, which are warmer than the surrounding tissues.
Nematic liquid crystals are useful research tools in the application of magnetic resonance. Molecules that are dissolved in nematic liquid crystal solvents give a highly resolved NMR spectrum.
Some liquid crystals have been used in chromatographic separations, as solvents to direct the course of chemical reactions and to study molecular rearrangement and kinetics.
Oscillographic and TV displays using liquid crystal screens are also being developed. Other applications include radiation and pressure sensors, optical switches and shutters etc.