Fig. 2From: A comparison of commercial and custom-made electronic tracking systems to measure patient flow through an ambulatory clinicRadio frequency identification (RFID) system overview: (1) the patient is given an RFID tag. (2) The tag is swiped within a six-inch proximity of the radiofrequency card reader. (3) The reader LED light flashes confirming registration of the tag ID and swipe timeBack to article page