Chipless RFID based multi-sensor tag for printed electronics

This research presents the design and implementation of a chipless Radio Frequency Identification (RFID) multi-sensor tag on a flexible laminate. Along with the tag's primary function of data encoding for object identification purposes, the tag also incorporates moisture and temperature sensing functionalities within a compact size measuring a mere 15 x 16 mm2. The tag structure comprises of a total 29 resonators, with each resonator corresponding to one bit in the microwave response. The initial design utilized the bendable Rogers RT/duroid (R) 5880 within a frequency band of 5.48-28.87 GHz. To conduct a comprehensive comparative analysis, the tag design is optimized for two distinct substrates including Kapton (R) HN and PET. The optimization process involves exploring the utilization of both silver nanoparticle-based ink and Aluminum as radiators. The sensing feature was incorporated by deploying a thin film of Kapton (R) HN over the longest slot of the tag which acts as a moisture sensor. Temperature sensing feature was achieved by combining Stanyl (R) polyamide, a temperature dependent polymer, with Rogers RT/ duroid (R) 5880 which served as a fused substrate. The tag showcases a high code density of 12.08 bits/cm2 enabling it to efficiently label 229 unique items. Its unique features include flexibility, miniaturized design, printability, cost-effectiveness and multi sensing property.