Session: 16-01-01: Government Agency Student Poster Competition

Paper Number: 150677

150677 - Leaf Wetness Measurement Using Uhf Chip-Based Rfid Sensor Through Impedance Mapping 

This research presents an innovative approach to sensing leaf moisture using chip-based UHF RFID tags, which involves fabricating the tag using additive manufacturing technology. Leveraging the recent acquisition of a DragonFly IV 3-D printer funded by NSF major research instrumentation (MRI) grant, this study aims to explore advanced manufacturing techniques in developing RFID sensors optimized for agricultural applications. Currently, the project is in the simulation stage, focusing on designing RFID sensors that operate at 915 MHz with an input impedance of 18-j164 ohms, tested on a model leaf to assess moisture levels. The moisture level in leaves is a critical indicator of a plant's health and the condition of the surrounding soil or land. As such, accurately measuring leaf wetness is essential, with wireless sensing technology playing a key role in this area of research. This study establishes a clear correlation between impedance and moisture content, aided by calibration curves that facilitate the determination of moisture content through real and imaginary impedance values. Furthermore, the research undertakes a practical approach by introducing a reader antenna to communicate with the tag, establishing a link between the Received Signal Strength Indicator (RSSI) and impedance variations. Simulation results are presented using Smith Chart analysis, displaying impedance values at different moisture contents due to change in dielectric properties. As moisture content increases, the impedance changes, indicating a direct relationship with dielectric properties. From the simulated results, initially, a reference impedance of 2.17 + j275.23 is set for 0% moisture content (MC). As MC increases, impedance also rises. This rise is due to changes in dielectric parameters, which correlate directly with MC. A correlation is observed, showing real impedance values ranging from 2.17 to 3.14 and imaginary impedance values from 275.23 to 277.11 across different MC levels. Preliminary simulation results have shown promising correlations between moisture levels and impedance variations, indicating the potential effectiveness of the proposed method. To validate the simulated result, we have fabricated the RFID tag using additive manufacturing technology with the help of DragonFly IV 3-D printing system. After fabrication, we have integrated the RFID tag with a reader antenna. To measure RSSI for each level of moisture of our leaf of interest, we have initiated by measuring the different levels of moisture following measuring dielectric parameters for each moisture level.  The leaf of interest is then attached with the tag to measure RSSI. We are determining mpedance for measured RSSI to establish the link between RSSI and impedances. We have initiated the experimental analysis with the fabricated tag to validated our simulated results. This work is particularly important in precision agriculture, where accurate monitoring of plant health and soil conditions is crucial for optimizing resource use and improving crop yields.

Presenting Author: Md Mirazur Rahman North Dakota State University

Presenting Author Biography: MD MIRAZUR RAHMAN received the B.S. degree in electrical, electronic and communication engineering from Military Institute of Science and Technology, Bangladesh in 2007 and the M.S. degree in wireless networks from Queen Mary University of London, UK in 2009. He is currently pursuing the Ph.D. degree in electrical and computer engineering at North Dakota State University, Fargo, ND, USA. Since 2022, he is a Research Assistant with the RF Connect Lab, Department of Electrical and Electronic Engineering, North Dakota State University, ND, USA. His research interest includes the development of metamaterial assisted phased array antennas for Satellite based IoT applications, chipless and chip-based RFID sensors for healthcare and precision agriculture. Mr. Rahman’s awards and honors include Fellowship from North Dakota Water Resources Research Institute (NDWRRI), and research grant from United States Department of Agriculture (USDA).

Authors:

Md Mirazur Rahman North Dakota State University
Shuvashis Dey North Dakota State University