If you're consenting it's, by definition, not battery. In the United States a generic definition of battery is "the use of force against another, resulting in harmful or offensive contact." Therefore, if you've consented you do not find such conduct offensive. Take a person punching another for example. If you were to walk up to me and punch me in the face and I found that harmful or offensive it would be battery. However, if we were in a boxing ring and we were both consenting, it was not illegal, harmful or offensive then it would not be.

Regarding implied consent, I'd have to say that knowingly entering the screening area would be considered implied consent. You don't HAVE to give consent, but if you don't you don't pass through the area and you don't fly. Same same with the explosive residue swabs. Once when I was asked if it was ok for them to do the test I asked "What if I say no?" The response was "That's within your rights but if you choose to exercise those rights you can't pass beyond this point."

Yeah... RIGHT...