What is a Pressure Sensor?

Working Principles of Pressure Sensors

• Strain gauge based pressure sensors also use a pressure sensitive element where metal strain gauges are glued on or thin film gauges are applied on by sputtering. This measuring element can either be a diaphragm or for metal foil gauges measuring bodies in can-type can also be used. The big advantages of this monolithic can-type design are an improved rigidity and the capability to measure highest pressures of up to 15,000 bar. The electrical connection is normally done via a Wheatstone bridge which allows for a good amplification of the signal and precise and constant measuring results. See our offer of strain gauge based pressure sensors.
• Capacitive pressure sensors use a pressure cavity and diaphragm to produce a variable capacitor. The diaphragm is deformed when pressure is applied and capacitance decreases accordingly. This change in capacity can be measured electrically and is then set in relation to the applied pressure. These sensors are limited to low pressures of roughly 40 bar.
• Piezo-resistive pressure sensors consist of a diaphragm – mostly made of silicon – with integrated strain gauges to detect strain as a result of applied pressure. These strain gauges are typically configured in a Wheatstone bridge circuit to reduce sensitivity and increase the output. Due to the material being used the pressure limitation is at around 1,000 bar.
• Unlike the aforementioned technologies – which all use the deflection of a measuring body – resonant pressure sensors use the changes in resonance frequency in a sensing mechanism to measure stress caused by applied pressure. Depending on the design of these sensors, the resonating element can be exposed to the media, where the resonance frequency then depends on the density of the media. Sometimes these sensors are also sensitive to shocks and vibration.