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Non-Contact Sensors

Non-contact sensors - what are they, how do they work and why use them?

Sensors are all around us, we come into contact with them continuously throughout the day. There are many different types of technologies used in different sensors. 

Some sensors are non-contact. This means that the sensor is using a technology that uses non-touching parts. This term non-contact or non-contacting usually refers to a position sensor that can measure movement or displacement in a rotary or linear fashion.  

What is a Non-Contact Sensor

A non-contact sensor uses wear-free technology, the sensor contains no friction on the moving parts, this eliminates wear and tear and mechanical failure. 

In recent years there has been more demand for non-contact sensors, this is mainly down to the requirement for longer service life and because some applications require measurement in demanding environments where non-contact sensors are more suitable. 

Why Use a Non-Contact Sensor

Non-contact sensors have many benefits, many of these are due to the fact they have no wearing parts;

  • Long life 
  • Fast response
  • Highly reliable 
  • Dependable 
  • Consistent excellent performance (no wear and tear)
  • More resistant to dust and dirt (than contacting alternatives)
  • Suitable for a range of environments 

Because of these benefits, non-contact sensors are used in industries including; factory automation, process and control, manufacturing, engineering, automation and intrinsically safe applications to name a few. 

Non-Contact Sensor Technologies 

There are different non-contact sensor technologies, they have different principles and are suitable for different applications. 

A few of these technologies which Variohm can help supply are;

Hall Effect Sensors are a rotary or linear type of non-contacting sensor, most of our Hall effect sensors are rotary. The principle uses a piece of semiconductor material passing continuous current through itself, when placed in a magnetic field the magnetic flux will force the electrons to the edge of the semiconductor, this produces a different force and alters the voltage. In a rotary sensor the semiconductor is mounted in an X format to give continuous rotational movement. For more information on Hall Effect sensor take a look at our blog post “What is Hall Effect” 

Inductive sensors work on a transformer principle and use alternating currents to measure linear position. They are unaffected by magnetic fields so are often used in high dynamic positioning tasks within many different industries. Find out more about Inductive Sensors here. 

LVDTs (linear variable differential transformer) are a linear measuring device, they use metal coils and a metal core. LVDTs are able to measure movements which are as small as one millionth of an inch up to several inches and sometimes further depending on the range of the LVDT. Find out more about LVDTs here

RVDTs (rotary variable differential transformers) are the rotary version of the LVDT. They operate on a similar principle but take measurements on rotary movements. For more information on RVDTs please contact us. 

Positek PIPS is a patented technology from our sister company Positek, these are available as either rotary or linear devices. PIPS ( Positek Inductive Position Sensor Technology) is similar to the LVDT and RVDT principle but it only uses one coil which gives a better stroke to length ratio. Find out more about PIPS here. 

Eddy current is a type of inductive measuring method, it uses the extraction of energy from an oscillating circuit. Eddy current uses alternating magnetic currents to determine the position of the given object. Sensors which use Eddy current technology are generally small in size so this measuring method is suited for applications where space is limited. For more information on this type of non-contact linear sensor take a look at our sister company Ixthus Instrumentation. 

Non-Contact Sensors from Variohm 

Within our range of non-contact sensors we have our new range of micro rotary sensors




These are based on our Euro-X range 


Euro- XPK


Our inductive sensors come from our supplier Novotechnik, they can be found on our website. 

We have a range of LVDTs and RVDTs from our supplier TE. Take a look at these on our website 

Take a look at the Ixthus Instrumentation website for Eddy current sensors

The Positek website contains information on the PIPs operating principle and all of the Positek products can also be found here. For a quick overview take a look at the Positek line card. 

For more information on any of the technologies we have discussed above or for help selecting a non-contact sensor please contact us

Article published on: 03/03/2020

Article last updated on: 03/03/2020