Pressure sensors are devices that sense the applied pressure of gases or liquids. The output of the measurement is then converted into an electrical signal which reflects the amount of pressure applied.
There are various technologies used within pressure sensors. Depending on the requirements, this can influence their sensing accuracy and reliability. When the mechanical displacement within the sensor is turned into an electrical output signal there are 5 ways this can happen.
Resistive - These types of sensors use the change in electrical resistance of a strain gauge connected to the diaphragm.
Capacitive - Are highly sensitive and are able to measure low pressure under 10 bar while still withstanding large overloads.
Piezoelectric - These sensors use substances like Quartz to generate a charge on the surface when pressure is applied. Piezoelectric pressure sensors are ideal for measuring fast changing pressures.
Optical - These use interferometry to measure pressure changes in optical fibre. They are not disturbed by EMI and can be used in noisy or medical environments.
MEMS - This stands for micro-electro-mechanical system and contains capacitive or piezo pressure sensing mechanisms on silicon at micron level resolution.
Types of Pressure Sensors
Within the sensors, there are various properties which can be used to classify them. This includes what pressure range they measure, their operating temperature range or the pressure type they measure.
Absolute Pressure Sensor - This type of sensor measures pressure relative to the perfect vacuum (zero reference point).
Gauge Pressure Sensors - These are often used to measure atmospheric pressure and are sometimes referred to as relative pressure sensors.
Sealed Gauge Pressure Sensor - Like a gauge pressure sensor except they measure pressure relative to a fixed pressure, not the current ambient atmospheric pressure which can vary.
Differential Pressure Sensors - These can be used to measure the difference between two different pressures (differential pressure) which can be connected to either side of the sensor. They are often used to measure pressure drops, fluid levels and flow rates.
Pressure Sensor Applications
Pressure sensors are used in many applications in a large range of industries. These include medical, aviation, automotive and marine.