Two essential aspects of any pressure sensing device are a force collector and transducer technology.
In the earliest pressure measurements, the transducer technique converted pressure into mechanical motion of a gauge or height of a liquid column. Aneroid cells, Bourdon tubes, bellows, diaphragms, deadweight testers and manometers provide the historical basis for the force collector in many pressure measurements. New semiconductor methods have been applied to previous vacuum sensing technology such as the Pirani gage (thermal conductivity) device.
Some of these technologies are used for high pressure measurements. Some are used for very low pressure measurements, such as the McLeod gauge or Pirani gauge which apply to vacuum measurements (i.e. ionization gauges). System engineers with applications in these areas should investigate these alternate technologies more closely.
Converting Pressure into an Electrical Signal
With sensing playing an active role in modern control systems, pressure sensors must provide more than a readout for monitoring.
The need for an electrical output that can provide feedback in a control system is solved by the following sensing techniques:
- Magnetic, such as a linear variable differential transformer (LVDT)
- Resonant frequency
Some of these techniques address specific applications such as sensing very high pressure (i.e., fiberoptic technology or the high precision and accuracy requirement of instrument grade sensors.