I'm looking for a sensor that would activate at a certain distance from the magnet or whatever would be signaling the location. The distance would range from 2-30cm and there would be obstacles (fabric, human parts,...) in between so that sound and light sensors would probably not work. I would want to be able to change the distance that would activate it. So if I'd set it to 25cm it'd activate when the two parts would get closer than that.