Conductive inkjet printed antennas on flexible low-cost paper-based substrates for RFID and WSN applications

This thesis investigates inkjet-printed flexible antennas fabricated on paper substrates as a system-level solution for ultra-low-cost and mass production of RF structures. These modules are designed for the UHF Radio Frequency Identification (RFID) Tags and Wireless Sensor Nodes (WSN); however the approach could be easily extended to other microwave and wireless applications. Chapter 1 serves as an introduction to RFID technology and its capabilities while listing the major challenges that could potentially hinder RFID practical implementation. Chapter 2 discusses the benefits of using paper as a substrate for high-frequency applications, reporting its very good electrical/dielectric performance up to at least 1 GHz. The dielectric properties are studied by using the microstrip ring resonator. Brief discussion on Liquid Crystal Polymer (LCP) is also given in this chapter. Chapter 3 gives details about the inkjet printing technology, including the characterization of the conductive ink, which consists of nano-silver-particles, while highlighting the importance of this technology as a fast and simple fabrication technique especially on flexible organic (e.g.LCP) or paper-based substrates. Chapter 4 focuses on antenna designs. Four examples are given to provide: i) matching techniques to complex IC impedance, ii) proof of concept of inkjet printing on paper substrate through measurement results, iii) demonstration of a fully-integrated wireless sensor modules on paper and show a 2D sensor integration with an RFID tag module on paper. Chapter 5 concludes the thesis by explaining the importance of this work in creating a first step towards an environmentally friendly generation of "green" RF electronics and modules.M.S.Committee Chair: Dr. Manos Tentzeris; Committee Member: Dr. Gregory Durgin; Committee Member: Dr. Joy Laska

The Silver Lining: A Novel, Inkjet-Printed Mesh Coplanar-Slot Antenna for the UHF Band

The Federal Communications Commission (FCC) is opening up frequencies within the television range (400MHz to 700MHz) of the Ultra High Frequency (UHF) band for use in emerging technologies, such as cognitive radio networks and machine-to-machine communication. In order for manufacturers to produce affordable antennas that can be used in these emerging technologies, inexpensive antennas are required that meet these new spectrum needs. This paper presents a mesh coplanar-slot bowtie patch antenna fabricated using commercially available inkjet-printing technology. Two antennas were fabricated: a 27x21cm copper FR4 antenna with .25mm lines and a 27x21cm silver antenna with 2mm lines fabricated using inkjet-printing. The copper antenna was iteratively designed in High Frequency Software Simulator (HFSS) and measured using a network analyzer. Simulations and measured results, which show good agreement, verify the viability of merging the mesh and coplanar-slot topologies. The silver antenna is a variation of the copper antenna that was iteratively altered in HFSS until the desired bandwidth was achieved. Simulations and measured results, which show good agreement, verify the viability of inkjet-printing as a fabrication method. The radioelectrical performance of the antennas were also compared to each other. Although there was slight variation between the resonant frequency and bandwidth, an adequate agreement was observed between the two antennas. This demonstrates the feasibility of using inkjet-printing as a quick, efficient method to fabricate UHF antennas that can take advantage of emerging spectrum and be used in applications such as cognitive-radio-networks and machine-to-machine communication.https://scholarscompass.vcu.edu/uresposters/1274/thumbnail.jp

Design and development of novel radio frequency identification (RFID) tag structures

The objective of the proposed research is to design and develop a series of radio frequency identification (RFID) tag structures that exhibit good performance characteristics with cost optimization and can be realized on flexible substrates such as liquid crystal polymer (LCP), paper-based substrate and magnetic composite material for conformal applications. The demand for flexible RFID tags has recently increased tremendously due to the requirements of automatic identification in various areas. Several major challenges existing in today's RFID technologies need to be addressed before RFID can eventually march into everyone's daily life, such as how to design high performance tag antennas with effective impedance matching for passive RFID IC chips to optimize the power performance, how to fabricate ultra-low-cost RFID tags in order to facilitate mass production, how to integrate sensors with passive RFID tags for pervasive sensing applications, and how to realize battery-free active RFID tags in which changing battery is not longer needed. In this research, different RFID tag designs are realized on flexible substrates. The design techniques presented set the framework for answering these technical challenges for which, the focus will be on RFID tag structure design, characterization and optimization from the perspectives of both costs involved and technical constraints.Ph.D.Committee Chair: Tentzeris, Manos; Committee Member: DeJean, Gerald; Committee Member: Ingram, Mary; Committee Member: Kavadias, Stylianos; Committee Member: Laskar, Jo

Novel Manufacturing Methods and Materials for UHF RFID Tags in Identification and Sensing Applications

The continuously increasing amount of radio frequency identification tags needed in our daily lives, not forgetting the broadly widening concept of the Internet of Things, sets high demands on the tag materials selection and manufacturing processes. The huge amount of needed tags requires environmentally sustainable material selection together with the requirement of very low cost. In addition, the manufacturing capacity needs to be very high, hence high-volume capable production methods are needed. In addition to identification applications, also sensing applications established with radio frequency identification tags are of great interest in many application fields.This thesis reports the possibilities of radio frequency identification tags manufactured on eco-friendly substrate materials using conductive inks and photonic sintering. The used manufacturing methods use raw materials efficiently. Especially brush-painting together with photonic sintering is capable for low-cost high-volume manufacturing. In addition, the possibilities of radio frequency identification tags for humidity sensing applications are studied.The results of this thesis confirmed that the materials and processes studied in this thesis are suitable for environmentally friendly low-cost radio frequency identification tag manufacturing. Especially brush-painting of regular screen printing conductive inks, both silver and copper oxide ink, on wood and cardboard substrates combined with photonic sintering confirmed to be a very good choice for the application area focused in this thesis. Furthermore, especially the use of screen printable copper oxide ink for identification applications is a very low-cost possibility. The results showed that humidity sensing with passive ultra-high frequency radio frequency identification tags, which were manufactured with regular screen printing silver ink on wood substrate without any coating on the tag, is a very promising approach

Inkjet Printing of Paper-Based Wideband and High Gain Antennas

This thesis represents a major contribution to wideband and high gain inkjet-printed antennas on paper. This work includes the complete characterization of the inkjet printing process for passive microwave devices on paper substrate as well as several ultra-wideband and high gain antenna designs. The characterization work includes the electrical characterization of the permittivity and loss tangent for paper substrate through 10 GHz, ink conductivity data for variable sintering conditions, and minimum feature sizes obtainable by today’s current inkjet processes for metallic nanoparticles. For the first time ever, inkjet-printed antennas are demonstrated that operate over the entire UWB band and demonstrate gains up to 8dB. This work also presents the first fractal-based inkjet-printed antennas with enhanced bandwidth and reduced production costs, and a novel slow wave log periodic dipole array which shows minimizations of 20% in width over conventional log periodic antennas

Definition, Characteristics and Determining Parameters of Antennas in Terms of Synthesizing the Interrogation Zone in RFID Systems

The radio frequency identification (RFID) systems are gaining in popularity in automated processes of object identification in various socioeconomic areas. However, despite the existing belief, there is no universal RFID system on the commercial market that could be used in all user applications. All components of a developed solution should be carefully selected or designed according to the specification of objects being recognized and characteristics of their environment. In order to determine parameters of propagation or inductively coupled system, especially when it is dedicated to uncommon applications, a multiaspect analysis has to be taken into consideration. Due to complexity, the problem is reduced to analytical or experimental determination of RFID system operation range and a “trial and error” method is mostly used in the industry practice. In order to cope with the barriers existing in the RFID technology, the authors give the review of latest achievements in this field. They focus on the definition, comprehensive characteristics and determination of the antenna parameters. They also pay attention to the 3D interrogation zone (IZ) that is the main parameter in which multitude technical aspects of the RFID systems are gathered simultaneously, as regards the theoretical synthesis as well as market needs

Wearable flexible lightweight modular RFID tag with integrated energy harvester

A novel wearable radio frequency identification (RFID) tag with sensing, processing, and decision-taking capability is presented for operation in the 2.45-GHz RFID superhigh frequency (SHF) band. The tag is powered by an integrated light harvester, with a flexible battery serving as an energy buffer. The proposed active tag features excellent wearability, very high read range, enhanced functionality, flexible interfacing with diverse low-power sensors, and extended system autonomy through an innovative holistic microwave system design paradigm that takes antenna design into consideration from the very early stages. Specifically, a dedicated textile shorted circular patch antenna with monopolar radiation pattern is designed and optimized for highly efficient and stable operation within the frequency band of operation. In this process, the textile antenna's functionality is augmented by reusing its surface as an integration platform for light-energy-harvesting, sensing, processing, and transceiver hardware, without sacrificing antenna performance or the wearer's comfort. The RFID tag is validated by measuring its stand-alone and on-body characteristics in free-space conditions. Moreover, measurements in a real-world scenario demonstrate an indoor read range up to 23 m in nonline-of-sight indoor propagation conditions, enabling interrogation by a reader situated in another room. In addition, the RFID platform only consumes 168.3 mu W, when sensing and processing are performed every 60 s

Desenho de antenas para sensores passivos em materiais não convencionais

Doutoramento em Engenharia EletrotécnicaMotivado pela larga expansão dos sistemas RFID e com o desenvolvimento do conceito de Internet das Coisas, a evolução no desenho e métodos de produção de antenas em suportes de materiais alternativos tem tido uma exploração intensiva nos últimos anos. Isto permitiu, não só o desenvolvimento de produtos no campo da interação homem-máquina, mas também tornar estes produtos mais pequenos e leves. A procura de novas técnicas e métodos para produzir eletrónica impressa e antenas em materiais alternativos e, portanto, uma porta aberta para o aparecimento de novas tecnologias. Isto aplica-se especialmente no mercado dos sensores, onde o peso, o tamanho, o consumo energético, e a adaptabilidade a diversos ambientes, têm grande relevância. Esta tese foca-se no desenvolvimento de antenas com suporte em materiais não convenvionais, como os já testados papel e têxteis, mas também na exploração de outros, desconhecidos do ponto de vista eléctrico, como a cortiça e polímeros biodegradáveis usados em impressão 3D. Estes materiais são portanto usados como substrato, ou material de suporte, para diversas antenas e, como tal, as propriedades electromagnéticas destes materiais têm de ser determinadas. Assim, e apresentado neste documento uma revisão de métodos de caracterização de materiais, bem como a proposta de um método baseado em linhas de trasmissão impressas, e a respectiva caracterização electromagnética de diversos materiais. Além disso, são propostos desenhos de antenas para diversos cenários e aplicações utilizando os materiais anteriormente mencionados. Com esta tese concluiu-se que a utilização de materiais alternativos e hoje uma realidade e os resultados obtidos são muito encorajodares para o desenvolvimento de um conjunto de sensores para aplicações RFID com uma grande capacidade de integração.The advancement of the design and fabrication of antennas using textiles or paper as substrates has rapidly grown motivated by the boom of RFID systems and the developing concept of the Internet of Things. These advancements have allowed, not only the development of products for manmachine interaction, but also to make these products smaller and lighter. The search for new techniques and methods to produce printed electronics and antennas in alternative materials is therefore an open door for new technologies to emerge. Especially in the sensors market, where weight, size, power consumption and the adaptability to the target application, are of great importance. This thesis focuses on the development of antenna design approaches with alternative materials, such as the already tested paper and textiles, but also others relatively unknown, such as cork and biodegradable polymers used in 3D printing. These materials are applied to act as substrates, or support structures for the antennas. Therefore, their electromagnetic properties need to be determined. Due to that, a review of electromagnetic characterization methods, as well as the proposal of a custom method based on printed transmission lines, is presented in this document. Besides, several antenna designs, for di erent application scenarios, using the previously mentioned materials, are proposed. With this thesis it was proved that it is possible to develop passive sensors in di erent alternative materials for RFID applications and others, which shows great promise in the use of these materials to achieve higher integration in sensing and identi cation applications

Inkjet-printed sensors and via-enabled structures for low-cost autonomous wireless platforms

Fundamental research to implement the printed autonomous wireless sensor platform is studied in three aspects: fabrication method, material selection, and novel applications for autonomous sensing/communication. Additive fabrication processes, such as inkjet printing technology and electroless electroplating, are discussed and the additively created metal layers are characterized. Fundamentals for material characterization utilizing resonators are presented and electrical properties of flexible low-cost substrates like synthetic Teslin paper and Poly(methyl methacrylate) (PMMA) are characterized. Widely used flexible substrates for printing, such as Liquid Crystal Polymer (LCP) and Kapton (polyimide), are summarized and tabulated as well. Novel antenna-based applications for efficient and autonomous operation of wireless sensor system, such as an antenna on Artificial Magnetic Conductor (AMC) for wearable applications, an active beacon oscillator for Wireless Power Transfer (WPT), and a multiband RF energy harvester, are designed and their performances are experimentally verified. The printed RFID-enabled sensor topologies with/without RFID chip are discussed as a new sensor platform for autonomous wireless operation. Fully inkjet-printed via topology for system miniaturization and integration is proposed for the first time. Challenges, circuit modeling and experimental data are presented. Future and remaining work to implement the novel low-cost autonomous wireless sensor platform are also discussed.Ph.D