The touch sensor is a type of sensor that detects the touch of the hand or finger. The module produce a signal output if the metal pike of the sensor was touched. there's a built-in potentiometer where you can adjust the touch sensitivity. Turning the trimmer of the potentiometer to right (clockwise), the touch sensitivity increases, and it decreases when you turn it counter-clockwise. There are two built-in leds in the module, to shows the sensor has power voltage, and the sensor detects the touch.
See the code below for testing the functionality of the metal touch sensor module.
Code sample for analog and digital output of metal touch sensor module
Upload the code to Arduino and test the module. When you touch the metal sensor, the new value will display to serial monitor for analog output, and HIGH value will be displayed for the digital output.