A "sensor bar" is a device that helps a video game console or other electronic device sense or track the movement of a controller or other objects. Full definition
This part was almost identical to setting up a Wii — in fact, the Wii U uses a regular Wii sensor bar for the motion controllers. (zeboyd.com)
Do people really want the bother of sensor bars and alignment... (brutalgamer.com)
The Wii's sensor bar sits by the TV and gives out infrared lights that a camera in the remote picks up in order for the pointer to function. (techradar.com)