An Arduino can be connected to a little electronic gadget called the KY-031 Knock Sensor Module.
It resembles a miniature ear for your Arduino device!
The sensor can sense vibrations from taps and knocks, and it may communicate this information to the Arduino by sending it a signal.
It's utilized in a variety of entertaining tasks!
You could create a game where you have to knock on the sensor in order to get points, or you could design a doorbell that chimes when someone knocks on your door.
It's a neat method for adding touch sensitivity and interactivity to your Arduino projects.