sensor
noun /ˈsensə(r)/
  /ˈsensər/
 - a device that can react to light, heat, pressure, etc. in order to make a machine, etc. do something or show something- security lights with an infrared sensor (= that come on when a person is near them)
 Oxford Collocations DictionarySensor is used after these nouns:- motion
- pressure
- temperature
- …
 Word Origin1950s: from sensory, on the pattern of motor.