1. Classification by Measured Physical Quantity: Mechanical: length, thickness, displacement, speed, acceleration, rotation speed, mass, weight, force, pressure, torque; Acoustic: sound pressure, noise; Magnetic: magnetic flux, magnetic field; Thermal: temperature, heat, specific heat; Optical: brightness, color.

2. Classification by Physical Principle: Mechanical, electrical, optical, fluidic, etc.

Below are 20 common sensors that are widely used in our daily lives:

Temperature Sensor: Used to measure temperature, such as in thermostats and thermometers.

Humidity Sensor: Used to measure air moisture, common in weather stations and HVAC systems.

Light Sensor: Detects light intensity, used in automatic lighting systems.

Sound Sensor: Used to detect sound intensity, common in audio equipment and security systems.

Pressure Sensor: Measures liquid or gas pressure, used in automotive manufacturing and meteorology.

Position Sensor: Used to measure the displacement or position of objects, such as in robotic arms and vehicles.

Accelerometer: Measures acceleration, widely used in smartphones and motion tracking devices.

Magnetic Sensor: Detects magnetic fields, such as for compasses and magnetometers.

Proximity Sensor: Detects the presence of nearby objects, common in touchscreens and automatic switches.

Capacitive Sensor: Measures changes in capacitance, often used in touchscreens.

Gas Sensor: Used to detect specific gases, such as carbon monoxide and carbon dioxide sensors.

Color Sensor: Detects the color of objects, widely used in printing and packaging industries.

Biological Sensor: Used to monitor biological parameters, such as heart rate and blood glucose levels.

Speed Sensor: Measures object speed, used in vehicle speedometers and speed cameras.

Weight Sensor: Measures object weight, used for weighing and load control.

Infrared Sensor: Detects infrared radiation, used in remotes and human body detection.

Pressure-sensitive Sensor: Detects contact based on applied pressure, such as on touchscreens.

Radio Frequency Identification (RFID) Sensor: Used to identify and track objects, common in logistics and inventory management.

Photodetector: Detects light signals, widely used in cameras and scanners.

Angular Position Sensor: Measures the angle or orientation of objects, used in aviation navigation and robotics.

These sensors form the foundation of modern technology, improving life quality, production efficiency, and safety across various industries.