Don't insult the sonic! [For a split second he does seem rather offended.] It's very effective. Not so much against wood. But I can work on that.

I'll just point it at you and it'll scan for the chip frequency that it's sending out. [And to demonstrate, he points it at himself. It doesn't seem like much is happening at first but then the probe's LED screen lights up showing a chip at the back of the Doctor's head.] See? Harmless.