Liquid Crystal Thermometer And Its Classification

A plastic strip thermometer or liquid crystal thermometer is a type of thermometer which contains heat sensitive liquid crystals. The liquid crystals in the plastic strip changes colour to indicate the dissimilar temperatures. Liquid crystals have the mechanical properties of a fluid, but need the visual properties of a single crystal. Change in temperature can affect the colour of a liquid crystal. It is used for temperature measurement. The firmness of the liquid crystal sensors is in the 0.1 range. Non-refundable liquid thermometers have been developed for medical use and for home purpose. If the thermometer is black and it is put onto somebody’s forehead, based upon the temperature of the person the colour will be changed.


Liquid crystals are of two types they are

  • Hot nematic stage
  • Cold nematic stage

Hot nematic stage:

The hot nematic stage is near the liquid phase. The molecules are easily moved from place to another place in the in some measured order.

Cold nematic stage:

The cold nematic stage is near the solid phase. The molecules are align themselves into strongly curled chiral conditions.


Liquid crystal thermometers show the temperature as colours and can be used to follow the change in the temperature that is produced by heat flow. We can observe the flow of heat by convection, conduction and radiation.

In medical fields, the liquid crystal thermometer is used to read the body temperature by placing the thermometer against the forehead.

Compared to the mercury in glass thermometer, liquid crystal thermometer is safer. By using analytic liquid thermometer we can see the exact results of the temperature which is between the 35.5  and 40.5  (Celsius)

Liquid crystal thermometers are used in home brewing, aquariums and in mood rings.

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