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The majority of pressure sensors do not measure the pressure directly. The sensor consists of a sensing element that takes a primary reading (most commonly deformation followed by displacement, force or strain) and translates it to another non-electric physical quantity. Another sensor then translates this into an electrical signal that represents the output of the pressure sensor.

1.  A change in pressure causes the diaphragm to deflect, a corresponding change in resistance is induced on the strain gauge.
2. This changes can be measured by DAQ system.
3.  A metal is strongly bonded in the nearby surface where the strain is being measured.
4.  Bonded foils have quick 1000 Hz response times to changes in pressure as well as their large operating temperature.

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Types of pressure sensors

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-       Sensors are of great use in underwater projects. They help to study the oxygen level and requirement.

What is a pressure sensor?

   Monitor the pressure of fluid, solid or gases.

  Most work based on piezoresistance.

  Level of electrical charges flow proportional to the level of pressure.

 Convert data into a form that can be displayed and understood by the user of another device.

Principle of Operation

The pressure sensing element is formed by diffusing semi-conductor strain gauges directly into the silicon diaphragm. Strain gauges are elements which change their resistance when they are deformed. The strain gauges are connected together to form a Wheatstone bridge circuit. When pressure is applied to the diaphragm, it deforms and stretches or compresses the strain gauges, which causes an imbalance in the bridge circuit, and a change in the output voltage.

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Selecting a Sensor

The easiest way to select a sensor is to choose the ones that will meet our technical requirements at the lowest cost.

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References

1. Ripka, P. and Tipek, A., 2007. Modern sensors handbook. 1st ed. Newport Beach, CA: ISTE USA.
2. Huddleston, C., 2007. Intelligent sensor design using the microchip dsPIC. 1st ed. Amsterdam: Elsevier/Newnes.
3. Engineers Garage. Available from: http://www.engineersgarage.com/articles/pressure-sensors-types-working

4. http://www.futek.com/pressure_sensor_selection.aspx