The sensor allows the pilot light to be automatically re-ignited if the flame is no longer present. The circuit is a surprisingly simple one, with a PNP transistor being turned on by the flame ...

Apple's patent application for "Organic light emitting diode having photodiodes" describes a setup that places photo sensors above, below, or in line with an OLED array to detect and compensate ...

A similar idea using arrays of light-emitting diodes as virtual sensors has also been explored in the internet of things community for skeleton posture and hand pose estimation.