Displacement sensors are generally categorised by the design of the assembly which also impacts whether or not it is suitable for a particular application. It is vital to understand these different design principles used in manufacturing displacement sensors to guide engineers in their sensor selection. This article takes a closer look at the advantages and disadvantages of each type of sensor design.

Inductive sensors 

Inductive sensors are often defined as a contactless switch that does not have any moving parts; thus, virtually not impacted by environmental conditions. Many sensors that are designed as inductive also follow the same underlying technology but improve on the durability and robustness. Inductive sensors are commonly used in industrial machines, food and beverage production, and sophisticated assemblies in aerospace engineering. Perhaps one of the most notable advantages of inductive sensors is that the technology is robust and reliable. Other benefits of inductive sensors include:

  • No mechanical wear and tear
  • Non-contact technology does not produce false positive signals
  • High-frequency range
  • Resistant to stress, and other environmental factors

Inductive sensor technology applies to different types of sensors such as a linear sensor, tilt sensor, and an angle sensor. Although inductive sensors are highly robust, some of the disadvantages of this design are low sensitivity and the dependence on the frequency of the input voltage.

Contact sensors 

The simplest type of sensor is a contact sensor or resistor which functions by converting the movement of an object using the resistance change of an electronic circuit. Contact sensor technologies such as potentiometers are low cost and easy to install. The downside of a contact sensor is the limited life cycle due to susceptibility to wear and tear. Other advantages of contact potentiometers include:

  • Small and compact assembly
  • Simple design
  • High linearity
  • Compatibility with AC and DC voltages

Apart from susceptibility to wear and tear, potentiometers are also subject to:

  • Damage to the sliding mechanism
  • High sensitivity
  • Susceptibility to noise
  • Small conversion

Despite these concerns, potentiometers remain one of the most widely used types of position sensors in applications that do not involve exposure to harsh working conditions.

Thermocouples 

A thermocouple is a type of contacting sensor that measures temperature. It functions using the thermoelectric effect principle. The primary advantage of using a thermocouple is its capability to measure a wide range of temperature values. Thermocouples are also simple to use, durable, and economical.

Digital semiconductor temperature sensors 

Sensors that use digital technology are usually more sophisticated. This type of digital temperature sensor only uses a single line to connect the sensor to the power source. Since the output is digital, the device is also compatible with computer software. Despite the sophistication, this type of sensor remains an economical choice for various industries that use them. One of the disadvantages of this type of sensor is low accuracy and relatively weak immunity. It also does not have an extensive measurement range and is not suitable when the application is related to heat transfer and subject to extremely high temperatures.

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