A sensor is a device or device that can sense a specified physical quantity and convert it into an available input signal according to a certain rule. Simply put, a sensor is a device that converts non-electricity into electricity.
The sensor usually consists of three parts: a sensitive component, a conversion component, and a measurement circuit.
1) A sensitive component is a component that can directly sense (or respond to) the measured component, ie, the sensitive component that is measured through the sensor is converted into a non-electrical quantity or other quantity that has a certain relationship with the measured.
2) The conversion component converts the above non-electric quantity into an electrical parameter.
3) The function of the measuring circuit is to convert the electrical parameters input by the converting component into measurable electric quantities such as voltage, current or frequency for display, recording, control and processing.