Digital Sensors and Their Principles

Piezoelectric Accelerometer

• Measures acceleration by converting mechanical vibrations into electrical signals
• Based on the piezoelectric effect: material produces voltage when subjected to mechanical stress

Digital Sensor

• Produces digital output signals
• Typically employs an analog-to-digital converter (ADC) to convert analog readings to digital values

Metallization in Piezoelectric Quartz Sensor

• Provides electrical contacts for the quartz crystal
• Enhances the sensor's sensitivity by concentrating the electric field

Active vs. Passive Sensors

• Active sensors: require external power source to operate and generate their own signals
• Passive sensors: don't need external power, they rely on changes in their environment to produce a signal

Power-Meter Application

• Measures power in electrical circuits and systems
• Used in various applications like home energy monitoring, industrial control, and research

Piezoelectric Material Characteristic

• Produces an electric charge when subjected to mechanical stress or strain
• Can be used to sense vibrations, pressure, and acceleration

Sensors Requiring External Power

• Active sensors, such as light-emitting diodes (LEDs) and laser sensors, need external power for operation

LVDT Principle of Operation

• Linear Variable Differential Transformer (LVDT) measures displacement by detecting variations in the magnetic field produced by a moving core inside a coil assembly

Accelerometer Sensor Type

• An accelerometer is an inertial sensor, meaning it measures acceleration relative to an inertial frame of reference

LVDT Advantage

• Offers high accuracy, repeatability, and resolution in displacement measurements
• LVDTs are also resistant to environmental factors like temperature and humidity

Proof Mass and Sensing Plates in MEMS Accelerometer

• Proof mass: a tiny weight inside the sensor that moves in response to acceleration
• Sensing plates: detect the movement of the proof mass and convert it into an electrical signal

MEMS Accelerometer System Type

• Micro-Electro-Mechanical Systems (MEMS)

Active Sensor Principle

• Generates its own signal to interact with the environment and obtain information

Passive Sensor Output

• Produces a change in its electrical characteristics, such as resistance, capacitance, or inductance, due to the environment's influence

Digital Sensor Example

• A digital temperature sensor that outputs a digital value representing the measured temperature

Inductive Measurement Principle

• Based on the principle of electromagnetic induction
• Uses changes in the magnetic field to sense position, displacement, or other physical quantities

Passive Sensor Geometry

• The geometric structure of a passive sensor plays a crucial role in its sensitivity to environmental changes

Resistive Sensor Principle

• Relies on changes in electrical resistance in response to a physical stimulus
• Commonly used in pressure sensors and strain gauges