At one end is an LED and at the other the LDR, and when attached to a glove it provides a finger sensor without the fuss ... a voltage can be read by an Arduino. You can see it in action in ...

This solar tracker system uses the Arduino UNO ... the LDR are connected as INPUTs and position the servo motor at 90° then wait for a 2 seconds before the code execution inside the loop(). In the ...