scholarly journals Humidity-Sensing Chipless RFID Tag with Enhanced Sensitivity Using an Interdigital Capacitor Structure

Sensors ◽  
2021 ◽  
Vol 21 (19) ◽  
pp. 6550
Author(s):  
Junho Yeo ◽  
Jong-Ig Lee ◽  
Younghwan Kwon
Keyword(s):  
Radio Frequency Identification ◽  
Vertical Direction ◽  
Peak Frequency ◽  
Resonant Peak ◽  
Humidity Sensing ◽  
Interdigital Capacitor ◽  
Array Configuration ◽  
Enhanced Sensitivity ◽  
Chipless Rfid ◽  
Humidity Chamber

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.

scholarly journals High-Density 3D Printable Chipless RFID Tag with Structure of Passive Slot Rings

Sensors ◽  
2019 ◽  
Vol 19 (11) ◽  
pp. 2535 ◽  
Author(s):  
Zhonghua Ma ◽  
Yanfeng Jiang
Keyword(s):  
Radio Frequency Identification ◽  
Low Cost ◽  
Vertical Direction ◽  
High Sensitivity ◽  
High Density ◽  
Frequency Spectra ◽  
Rfid Tag ◽  
Rectangular Slot ◽  
Chipless Rfid ◽  
Electric Field Direction

A three-dimensional (3D) printable chipless radio frequency identification (RFID) tag, with high density and sensitivity, is proposed and fulfilled on insulator substrates. By printing a rectangular slot ring and designing specific geometry on the substrate, the printed structure shows high sensitivity in a resonant manner, with the benefits of high density and low cost. Considering the multiple rectangular rings with different sizes in a concentric distribution, a bit coding sequence can be observed in frequency spectra because of the corresponding different resonant frequencies aroused by the printed slots. In this way, the 3D printable chipless RFID tag can be fulfilled by adopting the structure of the rectangular slot ring on the insulated substrates. The main characteristics of the designed rectangular slot rings are verified on both flexible and solid substrates. A 12-bit chipless tag based on the slot ring structures is designed and implemented. The simulation and experiment results show good agreement on its characteristics. The frequency response reveals the fact that the 2th, 3th and 4th harmonic do not exist, which is a unique merit for improving the encoding capacity and the sensitivity of the corresponding reader. The electric field direction of the electromagnetic wave of the reader excitation tag is demonstrated to be wide, up to 90° on the tag horizontal plane, 30° on the vertical direction.

scholarly journals Interdigital Capacitor-Based Passive LC Resonant Sensor for Improved Moisture Sensing

Sensors ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 6306
Author(s):  
Kristian Chavdarov Dimitrov ◽  
Sanghun Song ◽  
Hyungjun Chang ◽  
Taejun Lim ◽  
Yongshik Lee ◽  
...  
Keyword(s):  
Radio Frequency Identification ◽  
Frequency Offset ◽  
Detection Distance ◽  
Moisture Sensor ◽  
Interdigital Capacitor ◽  
Enhanced Sensitivity ◽  
Low Profile ◽  
Frequency Identification ◽  
Fringing Capacitance ◽  
Moisture Sensing

Herein, a passive low-profile moisture sensor design based on radio frequency identification (RFID) technology is proposed. The sensor consists of an LC resonant loop, and the sensing mechanism is based on the fringing electric field generated by the capacitor in the circuit. A standard planar inductor and a two-layer interdigital capacitor (IDC) with a significantly higher fringing capacitance compared to that of a conventional parallel plate capacitor (PPC) are used, resulting in improved frequency offset and sensitivity of the sensor. Furthermore, a sensor tag was designed to operate at an 8.2 MHz electronic article surveillance (EAS) frequency range and the corresponding simulation results were experimentally verified. The IDC- and PPC-based capacitor designs were comprehensively compared. The proposed IDC sensor exhibits enhanced sensitivity of 10% in terms of frequency offset that is maintained over time, increased detection distance of 5%, and more than 20% increase in the quality factor compared to sensors based on PPC. The sensor’s performance as a urine detector was experimentally qualified. Additionally, it was shown experimentally that the proposed sensor shows a faster response to moisture. Both simulation and experimental data are presented and elucidated herein.

scholarly journals On the application of the EM-imaging for chipless RFID tags

2015 ◽  
Vol 2 (2) ◽  
pp. 86-96 ◽  
Author(s):  
M. Zomorrodi ◽  
N.C. Karmakar
Keyword(s):  
Radio Frequency Identification ◽  
Low Cost ◽  
60 Ghz ◽  
Rfid Tag ◽  
High Data ◽  
Data Encoding ◽  
Bending Effect ◽  
Chipless Rfid ◽  
Frequency Identification ◽  
Cost Item

The electromagnetic (EM) imaging technique at mm-band 60 GHz is proposed for data encoding purpose in the chipless Radio Frequency Identification (RFID) systems. The fully printable chipless RFID tag comprises tiny conductive EM polarizers to create high cross-polar radar cross-section. Synthetic aperture radar approach is applied for formation of the tag's EM-image and revealing the tag's content. The achieved high data encoding capacity of 2 bits/cm2in this technique based on a fully printable tag is very convincing for many applications. The system immunity to multipath interference, bending effect, and printing inaccuracy suggests huge potentials for low-cost item tagging. Tags are also readable through a tick paper envelop; hence secure identification is provided by the proposed technique.

A low-profile FSS-based high capacity chipless RFID tag for sensing and encoding applications

2021 ◽  
pp. 1-9
Author(s):  
Shahid Habib ◽  
Amjad Ali ◽  
Ghaffer Iqbal Kiani ◽  
Wagma Ayub ◽  
Syed Muzahir Abbas ◽  
...  
Keyword(s):  
Radio Frequency Identification ◽  
High Capacity ◽  
Frequency Selective Surface ◽  
Rfid Tag ◽  
Sensing Applications ◽  
Low Profile ◽  
Simple Geometry ◽  
Chipless Rfid ◽  
Frequency Identification ◽  
Good Agreement

Abstract This paper presents a polarization-independent 11-bit chipless RFID tag based on frequency-selective surface which has been designed for encoding and relative humidity (RH) sensing applications. The 10 exterior U-shaped resonators are used for item encoding whereas Kapton has been incorporated with the interior resonator for RH sensing. This radio-frequency identification (RFID) tag operates in S- and C-frequency bands. The proposed design offers enhanced fractional bandwidth up to 88% with the density of 4.46 bits/cm2. Both single- and dual-layer tags have been investigated. The simulated results are in good agreement with measured results and a comparison with existing literature is presented to show the performance. Simple geometry, high code density, large frequency signature bandwidth, high magnitude bit, high radar cross-section, and angular stability for more than 75° are the unique outcomes of the proposed design. In addition, RH sensing has been achieved by integrating the Kapton on the same RFID tag.

Design and characterization of novel fabric-based multi-resonators for wearable chipless RFID applications

2021 ◽  
pp. 004051752198978
Author(s):  
Huating Tu ◽  
Yaya Zhang ◽  
Hong Hong ◽  
Jiyong Hu ◽  
Xin Ding
Keyword(s):  
Radio Frequency ◽  
Radio Frequency Identification ◽  
Printed Circuit Boards ◽  
Signal Transmission ◽  
Circuit Boards ◽  
Cross Sectional ◽  
Rfid Tag ◽  
Response Characteristics ◽  
Chipless Rfid ◽  
Screen Printed

Nowadays, the chipless radio frequency identification (RFID) tag is attracting significant attention owing to its immense potential in tracking. However, most of the chipless tags are fabricated on hard printed circuit boards, and the wearable fabric-based chipless tag is still in the research stage. In this paper, a symmetrical 3rd L-shaped multi-resonator wearable chipless RFID tag is designed and screen-printed onto fabric. In order to investigate the influence of the non-uniform conductive layer on the signal transmission at high frequency, the surface and cross-sectional topographies of the printed conductive film are analyzed and the frequency response characteristics are simulated and measured. The obtained results show that the common fabric can be used as the substrate to screen print the L-shaped multi-resonators of the chipless RFID tag, and the quality of the screen printed line, especially a narrow line, significantly affects the radio frequency performance. For the screen-printed 3rd L-shaped stub resonators, the relative frequency shift compared with the simulation results are 0.99%, 0.88% and 2.26%, respectively. Generally, the surface morphology of fabric and screen-printed precision are critical in improving the performance of L-shaped multi-resonators.

scholarly journals Three-Dimensional Chipless RFID Tags: Fabrication through Additive Manufacturing

Sensors ◽  
2020 ◽  
Vol 20 (17) ◽  
pp. 4740
Author(s):  
Sergio Terranova ◽  
Filippo Costa ◽  
Giuliano Manara ◽  
Simone Genovesi
Keyword(s):  
Radio Frequency Identification ◽  
Low Cost ◽  
Three Dimensional ◽  
Rfid Tags ◽  
Metallic Surfaces ◽  
Data Encoding ◽  
Chipless Rfid ◽  
Frequency Identification ◽  
3D Printed ◽  
Promising Solution

A new class of Radio Frequency IDentification (RFID) tags, namely the three-dimensional (3D)-printed chipless RFID one, is proposed, and their performance is assessed. These tags can be realized by low-cost materials, inexpensive manufacturing processes and can be mounted on metallic surfaces. The tag consists of a solid dielectric cylinder, which externally appears as homogeneous. However, the information is hidden in the inner structure of the object, where voids are created to encrypt information in the object. The proposed chipless tag represents a promising solution for anti-counterfeiting or security applications, since it avoids an unwanted eavesdropping during the reading process or information retrieval from a visual inspection that may affect other chipless systems. The adopted data-encoding algorithm does not rely on On–Off or amplitude schemes that are commonly adopted in the chipless RFID implementations but it is based on the maximization of available states or the maximization of non-overlapping regions of uncertainty. The performance of such class of chipless RFID tags are finally assessed by measurements on real prototypes.

scholarly journals Current Progress towards the Integration of Thermocouple and Chipless RFID Technologies and the Sensing of a Dynamic Stimulus

Micromachines ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1019
Author(s):  
Kevin Mc Gee ◽  
Prince Anandarajah ◽  
David Collins
Keyword(s):  
Radio Frequency Identification ◽  
Extreme Environments ◽  
Proof Of Concept ◽  
Rfid Technology ◽  
Barium Strontium ◽  
Chipless Rfid ◽  
Dynamic Stimulus ◽  
Frequency Identification ◽  
Scattering Response

To date, no printable chipless Radio Frequency Identification (RFID) sensor-related publications in the current literature discuss the possibility of thermocouple integration, particularly for the use in extreme environments. Furthermore, the effects of a time-dependent stimulus on the scattering parameters of a chipless RFID have never been discussed in the known literature. This work includes a review of possible methods to achieve this goal and the design and characterization of a Barium Strontium Titanate (BST) based VHF/UHF voltage sensing circuit. Proof-of-concept thermocouple integration was attempted, and subsequent testing was performed using a signal generator. These subsequent tests involved applying ramp and sinusoid voltage waveforms to the circuit and the characteristics of these signals are largely extracted from the scattering response. Overall conclusions of this paper are that thermocouple integration into chipless RFID technology is still a significant challenge and further work is needed to identify methods of thermocouple integration. With that being said, the developed circuit shows promise as being capable of being configured into a conventional chipless RFID DC voltage sensor.

scholarly journals Frequency-Coded Chipless RFID Tags: Notch Model, Detection, Angular Orientation, and Coverage Measurements

Sensors ◽  
2020 ◽  
Vol 20 (7) ◽  
pp. 1843 ◽  
Author(s):  
Jahangir Alam ◽  
Maher Khaliel ◽  
Abdelfattah Fawky ◽  
Ahmed El-Awamry ◽  
Thomas Kaiser
Keyword(s):  
Cross Section ◽  
Radio Frequency Identification ◽  
Measurement Errors ◽  
Federal Communications Commission ◽  
Ultra Wideband ◽  
Mathematical Representation ◽  
Rfid Tags ◽  
Angular Orientation ◽  
Chipless Rfid ◽  
Frequency Identification

This paper focuses on the frequency coded chipless Radio Frequency Identification (RFID) wherein the tag’s information bits are physically encoded by the resonators’ notch position which has an effect on the frequency spectrum of the backscattered or retransmitted signal of the tag. In this regard, the notch analytical model is developed to consider the notch position and quality factor. Besides, the radar cross section (RCS) mathematical representation of the tag is introduced to consider the incident wave’s polarization and orientation angles. Hence, the influences of the incident wave’s orientation and polarization mismatches on the detection performance are quantified. After that, the tag measurement errors and limitations are comprehensively explained. Therefore, approaches to measureing RCS- and retransmission-based tags are introduced. Furthermore, the maximum reading range is theoretically calculated and practically verified considering the Federal Communications Commission (FCC) Ultra Wideband (UWB) regulations. In all simulations and experiments conducted, a mono-static configuration is considered, in which one antenna is utilized for transmission and reception.

scholarly journals Four-State Coupled-Line Resonator for Chipless RFID Tags Application

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 581 ◽  
Author(s):  
Wazie M. Abdulkawi ◽  
Abdel-Fattah A. Sheta
Keyword(s):  
Dielectric Constant ◽  
Radio Frequency Identification ◽  
Rfid Tags ◽  
Microstrip Resonator ◽  
Coupled Line ◽  
Chipless Rfid ◽  
Compact Size ◽  
Frequency Identification ◽  
The Cost ◽  
Good Agreement

A novel quad-state coupled-line microstrip resonator is proposed for compact chipless radio frequency identification (RFID) tags. The proposed resonator can be reconfigured to present one of four possible states: 00, 01, 10, and 11, representing, no resonance, resonance at f2, resonance at f1, and resonance at both f1 and f2, respectively. The frequency span between f2 and f1 can be easily controlled, thereby reducing the required spectrum. Moreover, the proposed technique allows the storage of a large amount of data in a compact size to reduce the cost per bit. A multi-resonator prototype consisting of six resonators is designed, analyzed, and experimentally characterized. This prototype is implemented on the RT Duroid 5880 substrate with a dielectric constant of 2.2, loss tangent of 0.0009, and thickness of 0.79 mm. The designed configuration can be reconfigured for 46 codes. Two complete the RFID tags, including the six resonators and two orthogonally polarized transmitting and receiving antennas, are implemented and tested. The first tag code is designed for all ones, 111111111111, and the second tag is designed as 101010101010 code. Experimental results show good agreement with the simulation.

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