Wireless Material Identification in the Recycling Chain Using Chipless RFID Tags

Abstract

The utility of chipless RFID technology for the identification of 8 materials (7 plastic types and glass) in the recycling chain is examined. We first demonstrate how the frequency response of 8 Circular Ring Resonators (CRR), designed to operate in the 1.5 - 6 GHz band, is used to encode 8 unique material IDs. Tagged items are inserted one at a time in front of a chipless RFID reader and the speed and accuracy of material identification, based on the ability to decode the tag’s frequency response, is determined. We demonstrate the ability to correctly identify material type using a random forest classifier with up to 93% accuracy while being 3-16X faster than other methods reported in the literature. A technique to further improve detection speed, taking measurements with lower resolution, at the cost of accuracy is then presented. Finally, future directions of exploration are discussed.