[ivconic]

Originally Posted by Esteban

Modern explosive detector can sniff a part of TNT in 200,000,000 part of air. The technique involved used xtal. and a organic sample glued in it. Some reptilian cells is the sample. Scientific discovered that certain animal cells react in presence of TNT. When the reaction between the small quantity of TNT in air and the sample is produced, the mass of xtal. suffers microchanges and oscillator suffers umbalancing.

Cool, but let's presume bomb is packed in several plastic layers and than hidden somewhere in the car...possibly covered with some usuall things.
So there are no TNT particles in air at all..
At crosses (usually controled by police) there are much people, cars, dust... heat...all other possible "particles" in air except TNT particles..
What than? Booooom!
Only possible way to locate DIY bomb is to search manually...even than is tough!