A sensor is a detection device that measures a physical property and transforms the sensed information into electrical signals or other required forms of information output. The information detected could be light, heat, magnetism, sound, motion, moisture, pressure, or any other physical stimulus.
A sensor is generally composed of four parts: a sensitive component, a conversion component, a conversion circuit, and an auxiliary power supply. The sensitive component detects the measured object and outputs a physical quantity signal that has a definite relationship with the measured object while the conversion component converts the physical quantity signal into electrical signals that will be amplified and modulated by the conversion circuit. The conversion component and the conversion circuit require auxiliary power supply in some cases.
The advancement of sensors allows an object to see, feel, hear, smell, and even taste. With the characteristics of miniaturization, digitization, intelligence, and multi-function, sensors have been applied in various filed such as medical equipment, home appliances, consumer electronics, transportation industry, etc.