sensor

A sensor is a device that detects and responds to some type of input from the physical environment. There are many different kinds of sensors, including temperature sensors, proximity sensors, pressure sensors, light sensors, motion sensors, ultrasonic sensors, etc.

When you hear of "sensor drift" that refers the low frequency change in a sensor with time. Drift generally decreases with the age of a sensor as the component parts mature.

Historical perspective: According to the Wall Street Journal in 2018, the revolution won't need batteries because a world covered in sensors is near at hand. The key to the next tech revolution will be small, battery-less computers that pull power from the air via a wireless base station. As small as a stack of three quarters, and always-on, the untethered sensors could replace many current machines. Today’s microchips still need too much power for this next wave of smart machines. But since the first computer was made, the energy efficiency of electronics has improved by more than a factor of a trillion. New microchips that use a minuscule amount of energy will power wearable tech, sensors, and smart cards. The downside? Surveillance and tracking devices whose emergence should give us all pause.