Related Clues:

• Light detectors
• Burglar alarm features
• Items on space probes
• Electric eyes, e.g.
• Detection devices
• They detect heat or motion
• Taste buds, essentially
• Security system components
• Motion detectors, e.g.
• They feel for you
• They pick up things
• Eyes and ears
• Radar guns, e.g.
• Photocells
• Motion detectors