Choosing A Pressure Sensor

doctor taking blood pressure reading

A dozen or more factors influence the right sensor choice

When comparing pressure sensors, there are a number of physical and performance attributes to be considered.  

Range

Firstly, you’ll want to consider the pressure range each sensor is capable of measuring and how that compares to the pressures you want to measure. You may also wish to consider proof pressure, the maximum pressure the device can withstand and then retain functionality when the pressure returns to the operating range, and burst pressure, the pressure that breaks the component such that fluids can leak (which may be dangerous in some applications).

Accuracy

Pressure sensors’ accuracy is an important performance attribute, which is typically given as a percentage of full-scale pressure over a certain temperature range. Some sensors also exhibit hysteresis, non-repeatability and non-linearity, which should be described on the data sheet, if they apply. Linearity is generally expressed as a percentage of full scale pressure, but there are two methods of measurement (best fit straight line and terminal point) which are not equivalent, so be sure to compare like with like. Long-term stability of devices is also desirable – look for low drift over time as well as good stability over a wide temperature and humidity range – while short-term stability after soldering can also be an issue if the device needs to be used straight away (some sensor types can take hours, or even weeks to stabilize).

Integration time

You should also consider how long you have to spend on integrating the sensor into your system. If time is short, a transducer with integrated signal conditioning electronics, temperature compensation, self-calibration, internal diagnostic functions and a digital output may be the best choice. However, if your system has specialist needs and you are working with appropriate design resources, your own custom implementation of the electronics could be the right choice, especially if you are prepared to calibrate the sensor after assembly.

Environment

Next, consider the environment the sensor will be operating in. Mechanical robustness may be an issue – the sensor’s specification may give an idea of its expected cycle life. The ability to withstand liquids or contaminants may be attained by selecting a stainless steel part (note that most gauge pressure sensors have a hole or vent in the packaging for reading atmospheric pressure which can get clogged with dirt). Sensitivity to shock and vibration is also particularly important to automotive, transportation and industrial applications.

Other factors

Some other vital parameters are the sensor’s response time (vital if real time feedback is required), energy efficiency (check the current consumption figures, especially for transmitters), and physical size. For hard to reach areas or portable equipment, you’ll be looking for a compact solution.  Modern sensors come in a variety of package sizes and options that also need to be investigated. For example, does the sensor need to be surface mounted onto a PCB or does it need to be mounted in a specific orientation? Both obviously have implications for packaging choice.

 

There are of course many other factors that determine pressure sensor choice in specialist applications, such as heavy-duty sensors for industrial and transportation systems, highly accurate sensors for instrumentation and medical equipment, and low cost sensors for consumer devices, but this summary is a good starting point.

If you'd like to read about pressure sensor technology selection in more detail, download our pressure sensor white paper, or visit our sensors page to find out more about other sensor technologies.

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