Yeo Junho, Lee Jong-Ig, Kwon Younghwan
School of ICT Convergence, Daegu University, 201 Daegudae-ro, Gyeongsan 38453, Gyeongbuk, Korea.
Department of Applied Electronics Engineering, Dongseo University, Busan 47011, Korea.
Sensors (Basel). 2021 Sep 30;21(19):6550. doi: 10.3390/s21196550.
An eight-bit chipless radio frequency identification tag providing humidity sensing and identification information is proposed. A compact, enhanced-sensitivity resonator based on an interdigital capacitor (IDC) structure is designed for humidity sensing, whereas seven electric-field-coupled inductor capacitor (ELC) resonators are used for identification information. These eight resonators are placed in a two-by-four array arrangement. A step-by-step investigation for the effect of varying the number of elements and array configuration on the resonant frequency and radar cross-section (RCS) magnitude of the IDC resonator is conducted. The RCS value of the resonant peak frequency for the IDC resonator increases as the number of array elements placed nearby increases due to the mutual coupling among the elements, and the increase in the RCS value becomes larger as the number of arrays increases in the vertical direction. Polyvinyl alcohol (PVA) is coated on the IDC-based resonator at a thickness of 0.02 mm. A non-reflective temperature and humidity chamber is fabricated using Styrofoam, and the relative humidity (RH) is varied from 50% to 80% in 10% intervals at 25 °C in order to measure a bistatic RCS of the proposed tag. The humidity sensing performance of the IDC resonator in the proposed tag is measured by the shift in the resonant peak frequency and the RCS value, and is compared with a single ELC resonator. Experiment results show that when RH increased from 50% to 80%, the sensitivities of both the resonant peak frequency and the RCS value of the IDC resonator were better than those of the ELC resonator. The variation in the RCS value is much larger compared to the resonant peak frequency for both IDC and ELC resonators. In addition, the resonant peak frequency and RCS value of the PVA-coated IDC-based resonator change, whereas those of the other seven resonators without a PVA coating do not change.
提出了一种提供湿度传感和识别信息的八位无芯片射频识别标签。设计了一种基于叉指电容器（IDC）结构的紧凑型、高灵敏度谐振器用于湿度传感，而七个电场耦合电感电容（ELC）谐振器用于识别信息。这八个谐振器以2×4阵列的形式排列。对改变元件数量和阵列配置对IDC谐振器的谐振频率和雷达散射截面（RCS）幅度的影响进行了逐步研究。由于元件之间的相互耦合，靠近放置的阵列元件数量增加时，IDC谐振器谐振峰值频率的RCS值会增加，并且随着阵列在垂直方向上数量的增加，RCS值的增加会变得更大。在基于IDC的谐振器上涂覆厚度为0.02 mm的聚乙烯醇（PVA）。使用聚苯乙烯泡沫塑料制作了一个无反射温湿度室，并在25℃下将相对湿度（RH）以10%的间隔从50%变化到80%，以测量所提出标签的双站RCS。通过谐振峰值频率的偏移和RCS值来测量所提出标签中IDC谐振器的湿度传感性能，并与单个ELC谐振器进行比较。实验结果表明，当RH从50%增加到80%时，IDC谐振器的谐振峰值频率和RCS值的灵敏度均优于ELC谐振器。对于IDC和ELC谐振器，RCS值的变化相比于谐振峰值频率要大得多。此外，涂覆PVA的基于IDC的谐振器的谐振峰值频率和RCS值会发生变化，而其他七个未涂覆PVA的谐振器的谐振峰值频率和RCS值则不会改变。
