Research On Paper-based Chipless RFID Humidity Sensor Based On Graphene Oxide

As an application of Radio Frequency Identification(RFID)technology,chipless RFID humidity sensors can detect ambient humidity in real time without contact in a variety of scenarios.The paper substrate has the advantages of low cost,moisture absorption,etc.,and is suitable for chipless RFID humidity sensors.Due to the high dielectric loss of paper-based and its own limited moisture absorption ability,paper-based RFID humidity sensors have the problem of poor quality factor and low sensitivity.This paper aims to improve the performance of paper-based chipless RFID humidity sensors,and conducts research from sensitive material selection and dielectric constant testing,sensor structure design,substrate selection,sensor moisture sensitivity testing,etc.,and the research content includes the following parts:To study the variation of dielectric parameters with humidity under radio frequency of graphene oxide(GO,Graphene Oxide)moisture-sensitive materials.Using HFSS RF simulation software,a dielectric constant detection resonator with an operating frequency of2.45 GHz and a microstrip line resonant structure is designed.The effects of loading mass concentrations on resonant characteristics of 1%,2% and 5% GO films under the condition of30%RH～99%RH humidity were experimentally tested,and compared with the simulation results,the data of the real and imaginary parts of the dielectric constant of the three concentrations of GO films at 2.45 GHz with the change of ambient humidity were extracted,which provided a basis for the optimization of the moisture sensitive material of the chipless RFID humidity sensor for the follow-up.A highly sensitive GO-based paper-based humidity sensor is designed,and the resonator structure is designed and optimized by HFSS,and a circular inductor-fork-referent capacitive structure with a high-quality factor with a resonant frequency of 2.45 GHz is obtained.Using the GO RF dielectric constant obtained above,the moisture sensitivity of paper-based and GO paper-based sensors is simulated.The resonance characteristics and moisture sensitivity characteristics of pure paper-based sensors based on A4,Kodak and double-sided coated paper were made and tested,and the effect of paper-based type on sensor performance was studied.Select the best resonance characteristics,the highest sensitivity of the double-sided coated paper as the substrate,the production of 1%,2%,5% GO sensitive film humidity sensor,the sensitivity of the three sensors and other indicators of testing,the results show that the good hygroscopic performance of the paper substrate and GO moisture sensitive material synergy,can significantly improve the sensor sensitivity,5% GO sensor sensitivity to 4.34 MHz / %RH.In order to broaden the application scenario of GO in the field of humidity sensors,a paperbased chipless RFID humidity sensing tag with both 8bit coding function and moisture sensing function was designed.Using the polarization characteristics of the elliptical ring resonator,the paper-based chipless RFID humidity sensing tag based on the nested elliptical ring structure was designed by HFSS,and its different code word and moisture sensitivity characteristics were simulated in the polarization direction of the two electric fields to verify its coding reliability and good sensitivity.