Optimizing the number of printed layers in a PET inkjet-printed chipless RFID sensor

This paper presents a preliminary optimization study of the performance of conductive resonators inkjet-printed on polyethylene terephthalate (PET) with an increasing number of printed layers in a range 1-20 layers. Samples were tested and the amplitude of the frequency response was demonstrated to follow a power function with the increasing number of layers. Results indicate that with only 2 printed layers the signal intensity approaches 70% of the maximum intensity obtained with the highest number of layers (20), and that with 5 printed layers the signal reaches 83%. This demonstrates that only few deposited layers can be considered a good compromise for the production of Radio-Frequency IDentification (RFID) resonators by inkjet-printing on PET. Finally, the selected sample was tested as a chipless humidity sensor in a configuration with a 150µm-thick Nafion 117 sensitive material.