Novel Inkjet-Printed Chipless Tags for Radio-Frequency-Identification Applications

Abstract

In radio-frequency-identification (RFID) systems, chipless tags, i.e., tags without microchips, are desirable in comparison to their more common counterparts involving microchips. This is not merely due to the extra costs of microchips but also due to relatively difficult mounting processes to attach microchips onto metallic antennas, which in fact becomes challenging if tags are produced via inkjet printing methods. In the context of paper-based inkjet printing, absence of microchips is also attractive for green technology, since tags that contain only paper and metallic prints may be easier to recycle. On the other hand, the resulting RFID systems need to operate in a range of frequencies (rather than operating at a single frequency) in order to encode bits based on frequency-dependent responses of tag structures. In addition, one must consider potential difficulties in accurate and reliable identification, especially due to typically low signal levels. These difficulties, together with other constraints, such as compactness and being easy to fabricate, make it an essential task to design suitable tag geometries for chipless RFID systems.