Disclosed are systems and methods for utilizing a plurality of RFID readers as proximity sensors to detect one or more RFID tagged assets. In one embodiment, an array of RFID readers provides a coverage area and polls one or more tagged assets at a predetermined interval. If a tagged asset is removed from the coverage area, it will not be able to respond to the next RFID-reader poll, thereby indicating that it has been removed from the coverage area. One or more of the RFID readers may then provide a notification of this fact. In another embodiment, one or more RFID readers operating in combination with one or more RFID tags can be used to detect whether expendable items should be replaced, or whether a device should be allowed to be activated.