short to long-range detection thru surface

Does anyone have any idea how I could detect motion thru a surface say 1/2-2 inch pc of wood?

I was thinking something like a Proximity sensor or Ultra Sonic range sensor but could not find any information about if they could sense thru a surface?

I am trying to detect motion about 4 inch out from a wall with no visible sign of the device!

Hello! Detecting through a thick piece of wood is impossible with the ultrasonic range sensor or any IR based proximity sensor, since the wood would reflect and block any signal from getting through. A possible solution for detecting objects without any visible sensors is to use the ultrasonic sensor and a fine wire mesh to cover it; the ultrasonic pings might be able to get out and back through the mesh and the sensor itself would be hidden.


This looks like it is just what I need … fault.aspx
thanks franklin
I wonder how to use it with an arduino!