You apparently don't travel with either a medical device or a service animal. In the past, it was the medical device or service animal which was swabbed. But, patient advocates protested to DHS (TSA) that this was problematic for a delicate device and disturbing to the service animal. From those complaints, the system of swabbing the pax's hands so that neither the Officer nor the swab device (simply a stick with a piece of cloth clipped to it) actually touch the device or the animal.

This generally takes 30-45 seconds.