All About Cryometer

 All About Cryometer

In this article, we will discuss about cryometer, a scientific instrument for measuring temperatures of low degrees.

A cryometer is a category of thermometer used to detect low-range temperatures of different objects like solids, liquids, etc. It is specifically used to measure significant low temperatures of any object. In some thermometers, instead of mercury, ethanol filling is used, which can be used in meteorological measurements of low temperatures to the range of -70 degrees celsius (-94 degrees Fahrenheit). These thermometers  behave like cryometer devices. 

Types of cryometer

Different types of instruments may behave like a cryometer if they can be used to detect low temperatures of objects. 

Some of the different types of cryometer instruments are discussed below:


A thermocouple is an electrical device used to measure temperature. The working of thermocouples is dependent on two opposite types of electrical conductors present inside the device. The conductors form an electrical junction, which produces temperature-dependent voltage. So that the produced voltage is used to measure the required temperature of the objects. 

The main use of this thermometer is to measure a temperature value of about 1 Kelvin.

Vapour pressure thermometers

Vapour pressure thermometers are thermometers that use fluctuating saturation vapour pressure of a volatile liquid to measure temperature. They have the advantage of being error-free as it uses a very small bulb, which can avoid the errors caused by bulb expansion in other types of thermometers. 

The working of this thermometer depends on the equilibrium phase obtained between the liquid phase, which is filled in some volume in the thermometer, and the gas phase, which is obtained by the steam of filled volatile liquid. The major use of this thermometer is to measure a temperature value of about 0.5 Kelvin.

Resistance thermometers

Resistance thermometers, also known as Resistance Temperature Detectors (RTDs), are a kind of sensor used to measure temperature. The structure of these thermometers is made by using resistance temperature detector elements, in which pure RTD wire of generally platinum, nickel, or copper of fine length is wrapped around a core of glass or ceramic material. The main use of this thermometer is to measure a temperature value of about 0.01 Kelvin.

Melting curve thermometers

One of the most commonly used melting curve thermometers is a helium melting curve thermometer, which can be used to measure temperature in the range of 0.001 Kelvin to 0.5 Kelvin.

Resistance noise thermometers 

A resistance noise thermometer is also known as a Johnson noise thermometer. In this type of thermometer, the temperature can be directly estimated by monitoring tiny electrical fluctuations associated with random thermal migration of charge carriers (Johnson noise). This thermometer is used to measure a temperature of about 0.001 Kelvin.

Magnetic thermometers

A magnetic thermometer is a device which works on the principle of Curie’s Law. According to this law, the magnetic susceptibility of a paramagnetic substance is inversely proportional to the absolute temperature of the substance. This thermometer is used to measure a temperature of about 0.001 Kelvin.

Nuclear resonance thermometer

A nuclear resonance thermometer is generally used to measure a very low temperature of about 0.0000001 Kelvin. This thermometer is based on a temperature variation of Cl35 nucleus’s pure quadrupole resonance frequency (v0) using NQR absorption of KCLO3.

Limitations of Cryometer

Cryometers are generally used significantly to detect very low temperatures of objects. Cryometers will not work if any object has a high temperature. To measure high temperatures a clinical or laboratory thermometer is required, which can measure temperatures up to 200 degrees Celsius or 473 Kelvin. 


From the above discussion, it is clear that cryometers belong to the category of thermometers, which are particularly used to measure low temperatures. And the only range of the temperature which the cryometer can measure is the low range temperature which can not be detected by the normal medical or clinical thermometers.