What is a pressure sensor?

A pressure sensor is an electronic device that detects, regulates, or monitors pressure, and converts perceived physical data into an electronic signal. Pressure is defined as the amount of force (exerted by a liquid or gas) applied to a unit of “area” (P=F/A), and the traditional unit of pressure is the Pascal (which is one Newton per square meter). Pressure sensors often utilize piezoelectric technology, as piezoelectric elements give off an electric charge proportional to the stress (brought on by pressure) they experience. 

There are three main types of pressure sensors, and they each measure different types of pressure. Gauge pressure sensors measure relative to the ambient atmospheric pressure. This means that the readings are entirely dependent on the pressure of the air around the sensor. It is also affected by variables such as weather and altitude. When the gauge sensor experiences a pressure greater than atmospheric pressure, it is said to have a positive pressure. If the pressure is lower than atmospheric pressure, it is a negative pressure. Gauge pressure sensors are commonly used in liquid-level detection in a tank.  

The second type, absolute pressure sensors, measure pressure in reference to absolute zero pressure (or a vacuum). This allows for extremely precise pressure measurements, as its readings are in reference to no pressure as opposed to a varying atmospheric pressure. Absolute pressure sensors are often used as altimeters and barometers to measure atmospheric pressure. They are also used for detecting leaks in sealed containers.  

Diagram of a differential pressure sensor.
Diagram of a differential pressure sensor.  Source: First Sensor

The third type of pressure sensor, differential sensors, use two different pressure ports and measure the difference in pressure in reference to each other. Differential pressure sensors are mainly used to detect differences in pressure in tubes and water mains and monitor filtration systems.

Pressure sensors are also found in automobiles (to detect tire pressure or combustion pressure in an engine, factories (to regulate steam or water in machinery), and aircraft (to determine altitude and atmospheric conditions).