A sensor or transducer is a component that converts a measured physical quantity or chemical effect into an analog electrical signal. Physical quantities can be pressure, weight, acceleration, light intensity, temperature, humidity, radiation, sound, magnetic flux, rotational speed, and many other physical quantities.
Conversion of physical quantities into electrical quantities
The sensor senses the physical quantities and uses inductive, capacitive, piezoelectric, magnetic, field strength, radioactive, charge, or photoelectric transducers to convert them into an electrical voltage, which the sensor places in a fixed relationship to the input quantity. Thus, a sensor scales the signals to make them interpretable for further processing.
Sensors are divided into mechanical and non-mechanical sensors. The first group includes those for position, inclination, proximity, vibration, force, and pressure; and the non-mechanical ones include temperature sensors, light sensors and humidity sensors, magnetic field sensors, capacitive sensors, and chemical sensors. Position measurements can again be made using strain gauges, capacitive distance measurement, inductive length measurement, or resistive potentiometers. Proximity measurements can relate to people and security devices and be performed via ultrasonic motion detectors, infrared sensors, ultrasonic sensors or camera differential images. And temperature sensors range from PTC thermistors to thermistors, RTD elements, thermocouples and pyro sensors.
Use of sensors
In optical networks, in CD drives, DVD drives and BD drives, in scanners, digital cameras and camcorders, optical-to-electrical conversion is performed with light-sensitive sensors and image sensors. These include photodiodes, APD diodes, PIN diodes, phototransistors, and also CMOS sensors and CCD sensors.
Sensors are used in studios, process control, robots, safety devices and remote control systems, optical networks, CD players, automobiles, airplanes, production facilities and in many other technical, medical and scientific facilities. Very small sensors of only a few millimeters in size are called microsensors.
A distinction is made between wired sensors and wireless sensors. In addition, sensors can be equipped with their own intelligence, for example with a microprocessor or microsystems. In this context, the term smart sensor is used. From the design, sensors can be discretely built components, but in addition increasingly in microsystem technology( MST), as MEMS sensors, such as inertial sensors with integrated microcontrollers, radio chips, preamplifiers and digitizers, as they are realized in analog front ends( AFE).