Dear all, The idea is to detect break down of a group of blades inside a pipe. It’s very difficult to install any type of sensors inside a pipe without having them damaged, given that the pipe is an air vacuum suction system. How about concentrating on the physical properties of the blade itself. i.e.: Current conductivity, internal wire detection, to tell whether the blade is broken or not. We cannot observe the change in material resistivity or conductivity and tell by that, because that would require external circuitry or connections around the blades. What we need is some internal wiring. Any ideas? Please reply as soon as possible.