8 Pressure Sensors

Pressure Sensors

Pressure sensors are an important category among the types of load sensors. They play a critical role in various industries by measuring the force exerted by fluids (liquids or gases) on a surface. This chapter delves into how they function and the different types commonly used.

• Working Principles of Pressure Sensors

A pressure sensor (Figure 1) converts the force exerted by a fluid into a measurable electrical signal. There are three main working principles employed in pressure sensors:

• • Mechanical Deformation: This principle utilizes a component that physically deforms under pressure. The extent of deformation is then translated into an electrical signal. Examples include Bourdon tubes and bellows.
  • Piezoelectric Effect: Certain materials, like quartz crystals, exhibit the piezoelectric effect. When pressure is applied, these materials generate a corresponding electrical charge, proportional to the applied pressure.
  • Strain Gauge Technology: This approach utilizes strain gauges, which are tiny resistors that change their resistance when physically stretched or compressed due to applied pressure. This change in resistance is then converted into an electrical signal.

Figure 1: Pressure sensor (“Foam pressure sensor matrix” by Plusea is licensed under CC BY 2.0.)

• Different Types of Pressure Sensors

Here’s a closer look at some prevalent pressure sensor types:

• • Bourdon Tubes: These iconic C-shaped tubes bend slightly in response to pressure. The degree of bending is measured and converted into an electrical signal. They are commonly used for measuring moderate to high pressure in industrial applications.
  • Bellows: These consist of flexible, corrugated metal chambers that expand or contract under pressure. The displacement is then converted into an electrical signal. Bellows are well-suited for measuring high pressure and offer excellent sensitivity.
  • Semiconductor Pressure Sensors: These utilize a microscopic diaphragm etched onto a silicon chip. Pressure applied to the diaphragm causes a minute deflection, altering the electrical properties of the chip, which is then measured electronically. They offer high accuracy and a compact size, making them ideal for diverse applications.

• Applications of Pressure Sensors

The applications of pressure sensors are vast and encompass various industries:

• • Industrial Automation: Pressure sensors are used in monitoring and controlling fluid pressure in hydraulic and pneumatic systems, ensuring proper operation of machinery.
  • Automotive Industry: They play a crucial role in monitoring engine performance (oil pressure), tire pressure monitoring systems (TPMS), and controlling fuel injection systems.
  • HVAC Systems: Pressure sensors are essential for regulating air pressure in heating, ventilation, and air conditioning systems.
  • Medical Devices: They are used in blood pressure monitors, respiratory equipment, and other medical devices requiring precise pressure measurement.
  • Aerospace Industry: Pressure sensors are vital for monitoring fuel pressure, cabin pressure, and other critical parameters in aircraft.

For a more in-depth exploration of pressure sensors, a video lecture is available following this chapter. This lecture will provide further explanations and demonstrations of the concepts discussed.