Sensor bars are just emitting infrared light from 2 points bout a foot apart, and your device sees those to track movement. A candle will make more than enough IR to be seen.
Wanna have a bit of fun? Turn on a Wii sensor bar and point your phones camera at it.
*PSA* Wii Redump collector's can now unscrub ISO files. So scrubbed games can now be verified. You can find the program to do this here