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Types of sensors and their working principles: High Quality Notes

Types of Sensors and Their Working Principles

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Types of Sensors and Their Working Principles: High Quality Notes


1. Temperature Sensors

Types:

  • Thermocouples: Measure temperature using two different metals joined at one end. Voltage difference created correlates to temperature.
  • RTDs (Resistance Temperature Detectors): Change in resistance of metal with temperature.
  • Thermistors: Resistance decreases with increase in temperature.

Working Principle:

  • Thermocouples: Produce a voltage that varies with temperature.
  • RTDs: Use a material (often platinum) whose resistance changes predictably with temperature.
  • Thermistors: Use semiconductor materials with resistance inversely related to temperature.

Types of Sensors and Their Working Principles

2. Proximity Sensors

Types:

  • Inductive: Detect metal objects.
  • Capacitive: Detect any material that changes the dielectric constant.
  • Ultrasonic: Use sound waves to detect objects.
  • Photoelectric: Use light to detect objects.

Working Principle:

  • Inductive: Produce an electromagnetic field and detect changes when metal objects enter.
  • Capacitive: Measure changes in capacitance when objects approach.
  • Ultrasonic: Emit ultrasonic waves and measure reflection time.
  • Photoelectric: Emit a beam of light and detect reflection or interruption.

Types of Sensors and Their Working Principles

3. Pressure Sensors

Types:

  • Strain Gauge: Measures deformation.
  • Capacitive: Measures change in capacitance.
  • Piezoelectric: Measures electrical charge generated by pressure.

Working Principle:

  • Strain Gauge: Convert physical deformation into electrical resistance change.
  • Capacitive: Measure changes in capacitance caused by diaphragm movement.
  • Piezoelectric: Generate electrical charge when pressure is applied to a piezoelectric material.

4. Light Sensors

Types:

  • Photodiodes: Convert light into current.
  • Phototransistors: Similar to photodiodes but provide amplification.
  • LDRs (Light Dependent Resistors): Change resistance with light intensity.

Working Principle:

  • Photodiodes: Generate current proportional to light intensity.
  • Phototransistors: Provide amplified electrical response to light.
  • LDRs: Decrease resistance as light intensity increases.

5. Motion Sensors

Types:

  • PIR (Passive Infrared): Detects infrared light from warm objects.
  • Ultrasonic: Uses sound waves.
  • Microwave: Uses microwaves to detect motion.

Working Principle:

  • PIR: Detect infrared radiation changes.
  • Ultrasonic: Emit sound waves and measure reflection changes.
  • Microwave: Emit microwaves and detect changes in their reflection.
Types of Sensors and Their Working Principles

6. Humidity Sensors

Types:

  • Resistive: Measure resistance change with humidity.
  • Capacitive: Measure capacitance change with humidity.
  • Thermal Conductivity: Measure changes in thermal conductivity.

Working Principle:

  • Resistive: Use materials whose resistance changes with humidity.
  • Capacitive: Use materials whose dielectric constant changes with humidity.
  • Thermal Conductivity: Measure changes in the rate of thermal transfer.

7. Gas Sensors

Types:

  • Electrochemical: Generate current by chemical reaction.
  • Infrared: Measure absorption of infrared light.
  • Semiconductor: Measure changes in electrical conductivity.

Working Principle:

  • Electrochemical: React with target gas and produce electrical signal.
  • Infrared: Measure gas concentration by infrared light absorption.
  • Semiconductor: Change conductivity when gas interacts with sensor surface.

Summary | Types of Sensors and Their Working Principles

Types of Sensors and Their Working Principles

Understanding Sensors:

  • Sensors convert physical phenomena into readable electrical signals.
  • Each sensor type is designed for specific measurements and operates on distinct principles.

Applications:

  • Sensors are crucial in various applications including industrial automation, environmental monitoring, healthcare, and consumer electronics.

Importance:

  • Accurate sensor data is vital for control systems, safety, and efficient operation of devices and processes.

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