Hi there, is there a phidget sensor available that can detect a knock on a door? bearing in mind the door could be 3-4cm thick? Noise detection may not be a viable option as this is for a museum space.
You may have luck using an accelerometer, such as the MOT0100, to directly detect vibrations in the door. You would have to attach the sensor to the door near the hinges to prevent the sensor cable interfering with the operation of the door.
