The white line sensor is a critical component in the micro-mouse project . It contains two essential components which are the Light Emitting Diode and a Light Dependant Resistor .These two components work together to differentiate between a black and white surface .

The figure above shows basic design and layout of the white line sensor onto the micro-mouse.

Over a black surface the LDR has a high resistance leading to high values of V out , likewise over a white surface the resistance is low leading to lower values of V out. The V out is then used to determine whether the micro-mouse is on an white hence the white line following.