传感器是一种检测装置，能感受到被测量的信息，并能将检测感受到的信息，按一定规律变换成为电信号或其他所需形式的信息输出，以满足信息的传输、处理、存储、显示、 记录和控制等要求。它是实现自动检测和自动控制的首要环节。国家标准GB7665-87对传感器下的定义是：“能感受规定的被测量并按照一定的规律转换成可用信号的器件或装置， 通常由敏感元件和转换元件组成”。

可以用不同的观点对传感器分类：它们的转换原理(传感器工作的基本物理或化学效应)；它们的用途；它们的输出信号类型以及制作它们的材料和工艺等。

根据传感器工作原理，传感器分类可分为物理传感器和化学传感器二大类 ：

传感器工作原理的分类物理传感器应用的是物理效应，诸如压电效应，磁致伸缩现象，离化、极化、热电、光电、磁电等效应。被测信号量的微小变化都将转换成电信号。

化学传感器包括那些以化学吸附、电化学反应等现象为因果关系的传感器，被测信号量的微小变化也将转换成电信号。

有些传感器既不能划分到物理类，也不能划分为化学类。大多数传感器是以物理原理为基础运作的。化学传感器技术问题较多，例如可靠性问题，规模生产的可能性，价格问题 等，解决了这类难题，化学传感器的应用将会有巨大增长。

A sensor is a detection device that can sense the measured information and convert the detected information into electrical signals or other required forms of information output according to certain rules to meet the requirements of information transmission, processing, storage, display, recording and control. It is the first link to realize automatic detection and automatic control. The definition of a sensor under the national standard GB7665-87 is: "A device or device that can sense the specified measured information and convert it into a usable signal according to certain rules, usually composed of sensitive elements and conversion elements".
Sensors can be classified from different perspectives: their conversion principle (the basic physical or chemical effect of the sensor's operation); their purpose; their type of output signal, and the materials and processes used to make them.
According to the working principle of sensors, sensors can be classified into two categories: physical sensors and chemical sensors.
The classification of the working principle of the sensor The physical sensor applies physical effects, such as piezoelectric effect, magnetostriction phenomenon, ionization, polarization, thermoelectric, photoelectric, magnetoelectric and other effects. Small changes in the measured signal amount will be converted into electrical signals.
Chemical sensors include those that are caused by phenomena such as chemisorption and electrochemical reactions, and small changes in the measured signal amount are also converted into electrical signals.
Some sensors can neither be classified as physical nor chemical. Most sensors operate on the basis of physical principles. Chemical sensors have many technical problems, such as reliability problems, the possibility of large-scale production, price problems, etc. If these problems are solved, the application of chemical sensors will see tremendous growth.