In the microcontroller era today, Arduino is ... Here an LDR (Light Dependent Resistor) is used to measure the light level. The alarm system is triggered when a “Logic High (H)” level signal is ...

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 ...