Can an electronic detector be developed for security purposes for a common man to be safe from explosives and weapons and is it possible to have this security detector along with the cell phone?

Answer 1

As "weapons" encompasses a vast array of items, I'm going to assume that the question refers to weapons which use some sort of explosive in them, e.g. guns or bombs.

The detection of explosives other than by direct inspection (e.g. using X-Rays or similar methods to actually "see" the item) is done by chemical "sniffing" - that is, detecting trace amounts of vapors that explosives give off constantly.

In the case of cartridges used in guns, there's no real way to have a portable explosives sniffer be sensitive enough to detect ordinary mass-produced cartridges for firearms. These cartridges are sealed quite well, and only give off exceedingly small amounts of gases - so small, that even very large static scanners have an extremely hard time detecting it. Even items such as military grenades are likely to be sealed well enough to avoid giving off enough gas to be detected except by extremely sensitive equipment.

In the case of attempting to detect residue and vapors from hand-assembled explosive devices (handmade bombs and I.E.D. and such), there are several hand-held "sniffers" available. However, they are generally at least the size of a 1990s-era cell phone themselves. Also, remember that these devices generally have a range of a couple of feet - much less if the explosive items are inside something, or have only just been placed in the location.

As a practical manner, there is no way to build an explosives detector small enough to fit into a cell phone.