introduction

Sensors, as an important part of modern science and technology, are widely used in many fields such as industry, agriculture, medical, aerospace, and consumer electronics. They are like tentacles in the information world, which can capture and convert various signals from the physical world to provide a basis for intelligent control and decision-making. This article will delve into the fundamentals and classification of sensors to help readers better understand this key technology.

The basic principle of the sensor

The basic principle of the sensor is to convert the specific measured signal (such as force, temperature, light, sound, chemical composition and other physical quantities) into a certain usable signal (such as voltage, current and other electrical quantities) according to a certain law through sensitive elements and conversion elements, and output them to meet the requirements of information transmission, processing, recording, display and control. This conversion process makes it easy to measure, analyze, and utilize non-electrical quantities.

Specifically, a sensor usually consists of two parts: a sensitive element and a conversion circuit. The sensitive element is responsible for sensing the signal under test, and its characteristics (such as resistance, capacitance, inductance, etc.) will change with the change of the signal under test; The conversion circuit converts these changes into electrical signals, and through the signal processing circuit, it is amplified, filtered, linearized, etc., and finally outputs a standard signal that can be used by subsequent circuits or systems.

Classification of sensors

There are many ways to classify sensors, but here are two main dimensions:

1. Categorize by input

Physical sensor: A sensor that converts physical quantities (such as force, pressure, displacement, velocity, acceleration, temperature, light, sound, etc.) into electrical signals. For example, a temperature sensor outputs an electrical signal by sensing a temperature change to change the resistance value or the electromotive force generated by a thermocouple.

Chemical Sensor: A sensor that converts chemical quantities (such as gas concentration, humidity, pH, etc.) into electrical signals. These sensors typically use principles such as chemical reactions or chemisorption to detect and measure chemical quantities and convert them into electrical signals.

Biosensors: Sensors that use biomolecules or biological tissues to detect and measure biomass or chemical mass. Biosensors are highly selective and sensitive, enabling rapid and accurate detection of changes in biomolecules or biological tissues.

2. Categorized by working principle

Resistive Sensors: Sensors that use changes in resistance values to detect and measure physical or chemical quantities. For example, the resistance value of a thermistor changes with temperature, enabling temperature measurements.

Capacitive Sensors: Sensors that use the principle of capacitance to detect and measure physical or chemical quantities. The sensing element of this type of sensor usually consists of two metal plates, and the capacitance value of the sensor also changes when the distance or relative area between the two metal plates changes due to a change in the measured area.

Inductive sensors: Sensors that use the principle of electromagnetic induction to detect and measure physical or chemical quantities. The sensing element of an inductive sensor usually consists of a coil and an iron core, and the inductance value of the sensor changes when the change in the magnetic flux in the coil is caused by a change in the measured sensor.

Piezoelectric sensors: Sensors that use the piezoelectric effect to detect and measure physical or chemical quantities. The sensing element of a piezoelectric sensor is usually made of piezoelectric material, and when the change being measured causes the deformation of the sensitive element, an electric charge or voltage is generated inside it.

Photoelectric sensors: Sensors that use the photoelectric effect to detect and measure physical or chemical quantities. The sensing element of a photoelectric sensor is usually made of a light-sensitive material, and when the change in the measured light causes a change in light, the photocurrent of the sensor also changes.

conclusion

As a bridge between the physical and digital worlds, sensors have a variety of basic principles and classifications. Through an in-depth understanding of the basic principles of sensors and an understanding of different types of sensors, we can better apply this key technology and promote the intelligent development of various fields. In the future, with the continuous progress and innovation of science and technology, sensor technology will continue to develop and grow, bringing more convenience and well-being to human society.