Digital Sensors and Their Principles

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Questions and Answers

What is the primary purpose of a piezoelectric accelerometer?

To detect changes in magnetic fields

To convert mechanical energy into electrical energy

To quantify acceleration and vibrations (correct)

To measure temperature variations

What is a characteristic of a digital sensor?

It is highly sensitive to temperature changes

It outputs binary coded digital information (correct)

It provides an analog output signal

It can only measure linear displacements

What is the function of metallization in a piezoelectric quartz sensor?

To measure the resonant frequency of the quartz

To filter out noise in the signal

To constitute a capacitor that charges based on applied stress (correct)

To amplify the output signal

What is a key difference between active and passive sensors?

Active sensors require an external power source, while passive sensors do not Signup and view all the answers

What is a common application of a power-meter?

To measure the power consumption of a device Signup and view all the answers

What is a characteristic of a piezoelectric material?

It produces an electric charge in response to applied stress Signup and view all the answers

What type of sensors require an external power source to operate?

Active sensors Signup and view all the answers

What is the principle of operation of LVDTs?

Mutual induction Signup and view all the answers

What type of sensor is an accelerometer?

Capacitive sensor Signup and view all the answers

What is the advantage of LVDTs?

No friction and fully submersible Signup and view all the answers

What is the function of the proof mass and sensing plates in a MEMS accelerometer?

To measure the change in capacitance Signup and view all the answers

What is the name of the type of systems that the MEMS accelerometer is an example of?

Microelectromechanical systems Signup and view all the answers

What is the fundamental principle of active sensors?

They require an excitation that is modified by the sensor to produce the output signal. Signup and view all the answers

What is the output of a passive sensor?

An impedance value Signup and view all the answers

Which of the following is an example of a digital sensor?

IMU (Inertial Measurement Unit) Signup and view all the answers

What is the principle of operation of inductive measurement?

Mobile core inductor Signup and view all the answers

What is the characteristic of a passive sensor's geometry?

It is deformable Signup and view all the answers

What is the principle of operation of a resistive sensor?

Variable resistivity Signup and view all the answers

Study Notes

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

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Description

Explore the world of digital sensors and their operating principles. Learn about the different types of sensors, including passive and active sensors, and how they respond to external stimuli. Discover the role of impedance and excitation in sensor output.