I was looking at a BBC news article about the recent security alerts at airports when a thought occurred to me. One of the big challenges with electronic items is to ensure that they have not been modified to contain explosives. My thought is that explosives must add weight to a unit. If a list of known weights for particular devices could be published then equipment presented at airports could be weighed and the weight matched against a list provided by manufacturers.
If the weight didn’t match a known weight (within some margin of error) the device could be selected for further screening. Proof that the unit was operational would also be required obviously to prevent hollowing out the insides and replacing with explosives. However assuming a device worked and the weight hadn’t increased noticably above the standard set, then it would go some way to suggesting the item wasn’t harmful.
There are obviously some issues that this doesn’t cover, but it might be a useful and simple tool as part of a security screening procedure.