The sensing element in the Fido XT can be used for several hours, depending on the environment you are testing in. If you are testing and have not found any type of explosive substance then the sensing element will not 'clog' up as fast because there is not particulates that are attaching themselves to the side of the element; quenching the light.

Fido isn't for airport security. It's for small applications where you want to inspect explosive traces in particular situations. As far as I know it's single use, and you have to replace the polymeric/chemical sensor on each application.

Fido sensing elements are generally good for many hours of operation. The PaxPoint product is specifically intended for liquid screening in airports. The main limitation is that they need a focused target to work on. The holy grail is a walk-through chemical sensor, but the physics of that is challenging.