Piezo-resistive pressure transducers from Variohm EuroSensor

04 June, 2021

Pressure transducers, also known as pressure sensors or pressure transmitters, accurately sense pressure in gases and liquids and output the value as an analogue or digital signal in real time. The pressure, measured as the applied force by a fluid (liquid or gas) on a surface area, can be either an absolute value referenced to zero pressure, or a gauge value relative to ambient pressure, or a differential value between two independent pressure sources. Normally measured in units and sub-units of a bar, the output values can be a positive or a negative vacuum pressure.

Using the latest technology sensing and electronics elements, Variohm uses three main methods of building pressure transducers which are all piezo resistive approaches. The most used technology for the company’s product range is a resistive bridge printed onto a steel membrane with thin film measuring cells that are fully sealed in hermitically welded housings with no O-rings. According to Variohm EuroSensor, these products provide excellent performance characteristics in terms of stability, sensitivity, performance over temperature and handling of higher frequency applications.

The second technology has similar design characteristics but with a methodology where resistors are bonded onto the pressure transmitter membrane. This affords more freedom in the selection of the material for wetted parts and can therefore be used on applications that demand more stringent media compatibility requirements.

The third technology the company employs is based around a silicon chip which measures the applied pressure. This technology is the least robust against media and pressure peaks as it has internal O-Rings. However, due to the higher integration of the chip on the sensor’s PCB the cost of this technology allows more cost-effective products if the application is suitable.

A wide choice of industry compatible voltage or current outputs are available, as well as signal 1/3output options such as CANopen, J1939 (SAE-J1939) and HART. The same technology can also be employed as part of a pressure switch that will trigger a relay output when a pre-set pressure level is reached.

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