Near-field RFID sensor-sheets to detect objects and persons with No RFID tags attached

We have developed presence sensor-sheets using near-field radio-frequency identification (RFID) systems to detect objects and persons with no RFID tags attached. The sheet is composed of ordinary passive RFID tags and a near-field traveling-wave antenna as a reader antenna. The tags operate as proximity sensors utilizing the dependencies of tag antenna operations on their surroundings. Prototyping the sensor-sheets, we successfully demonstrated beverage bottle detection and human footprint recognition. We expect that this technology is applicable to the practical usage such as managing items on the store shelves, and monitoring people while protecting their privacy.