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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 decice.

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.

• Pressure measurement range
• Media to be measured – the amplified pressure sensors are suitable for all media, whereas the modules are only suitable for use with non-corrosive gas
• Material – Titanium is lighter than stainless steel but is susceptible to attack by some cleaning solvents and by methanol.
• Operating Temperature – Make sure the operating temperature is appropriate for our installation.
• Connector – Certain models are available with integral connectors. Other types have a flying lead.
• Mounting – Flanged versions of certain models are available.

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