Sensors are devices that detect and measure physical phenomena such as temperature, pressure, force, or acceleration, and convert them into electrical signals that can be processed and interpreted by other components of the vehicle. Sensors are used in various systems of a car, including the engine control system, the transmission, the suspension, the brakes, the safety systems, and the infotainment system. They allow the vehicle to respond to its environment, monitor its own performance, and communicate with other devices.
With advances in micromachinery and easy-to-use microcontroller platforms, sensors have expanded beyond the more traditional fields of temperature, pressure, or flow measurement, for example, into MARG sensors. Moreover, analog sensors such as potentiometers and force-sensing resistors are still widely used.
Applications include manufacturing and machinery, airplanes and aerospace, cars, medicine, and robotics. A sensor’s sensitivity indicates how much the sensor’s output changes when the input quantity being measured changes. For instance, if the mercury in a thermometer moves 1 cm when the temperature changes by one °C, the sensitivity is 1 cm/°C (the slope Dy/Dx assuming a linear characteristic).
Some sensors can also impact what they measure; for instance, a room-temperature thermometer inserted into a hot cup of liquid cools the liquid while the liquid heats the thermometer. Sensors need to be designed to have a negligible effect on what is measured; making the sensor smaller often improves this and may introduce other advantages.
Technological progress allows more and more sensors to be manufactured on a microscopic scale as microsensors using MEMS technology. A microsensor usually reaches a significantly higher speed and sensitivity than macroscopic approaches.