UHF Energy Harvesting and Power Management

As we are entering the era of Internet of Things (i.e. IoT), the physical devices become increasingly connected with each other than ever before. The connection between devices is achieved through wireless communication schemes, which unfortunately consume a significant amount of energy. This is undesirable for devices which are not directly connected to power. This is because these devices will essentially carry batteries to supply the needed energy for these operations and the batteries will eventually be depleted. This motivates the need to operate these devices off harvested energy. UHF energy harvesting, as an enabling technology for the UHF RFID, stands out amongst other energy harvesting approaches as it does not heavily rely on the natural surrounding environment and also offers a very good wireless operating range from its radiating energy source. Unlike the RFID, the power consumption and the operational range requirement of these IoT devices can vary significantly. Thus, the design of the RF energy harvesting front-end and the power management need to be re-thought for specific applications. To that end, in this thesis, discussions mainly evolve around the design of UHF energy harvesters and their associated power management units using lower power analog approaches. First, we present the background of the low power UHF energy harvesting, specially threshold-compensated rectifiers will be presented as a key technology in this area and this will be used as a build practical harvester for the UHF RFID application. Secondly, key issues with the threshold compensation will be identified and this is exploited either (i) to improve the dynamic power conversion efficiency of the harvester, (ii) to improve dynamic settling behaviour of the harvester. To exploit the ”left-over” harvested energy, an intelligent integrated power management solution has been proposed. Finally, the charge-burst approach is exploited to implement an energy harvester with -40 dBm input power sensitivity.Thesis (Ph.D.) -- University of Adelaide, School of Electrical & Electronic Engineering, 201

Radio Frequency Identification (RFID) based wireless manufacturing systems, a review

Radio frequency identification (RFID) is one of the most promising technological innovations in order to track and trace products as well as material flow in manufacturing systems. High Frequency (HF) and Ultra High Frequency (UHF) RFID systems can track a wide range of products in the part production process via radio waves with level of accuracy and reliability.   As a result, quality and transparency of data across the supply chain can be accurately obtained in order to decrease time and cost of part production. Also, process planning and part production scheduling can be modified using the advanced RFID systems in part manufacturing process. Moreover, to decrease the cost of produced parts, material handling systems in the advanced assembly lines can be analyzed and developed by using the RFID. Smart storage systems can increase efficiency in part production systems by providing accurate information from the stored raw materials and products for the production planning systems. To increase efficiency of energy consumption in production processes, energy management systems can be developed by using the RFID-sensor networks. Therefore, smart factories and intelligent manufacturing systems as industry 4.0 can be introduced by using the developed RFID systems in order to provide new generation of part production systems. In this paper, a review of RFID based wireless manufacturing systems is presented and future research works are also suggested. It has been observed that the research filed can be moved forward by reviewing and analyzing recent achievements in the published papers

Characterization and Design Methodologies for Wearable Passive UHF RFID Tag Antennas for Wireless Body-Centric Systems

Radio Frequency Identification (RFID) is a wireless automatic identification technology that utilizes electrically active tags – low-cost and low-power wireless communication devices that let themselves transparently and unobstructively be embedded into everyday objects to remotely track information of the object’s physical location, origin, and ownership. At ultra-high frequencies (UHF), this technology uses propagating electromagnetic waves for communication, which enables the fast identification of tags at large distances. A passive RFID tag includes two main components; a tag antenna and an RFID integrate circuit (tag IC). A passive tag relies solely on the external power harvested from an incident electromagnetic wave to run its circuitry and for data transmission. The passiveness makes the tag maintenance-free, simple, and low-cost, allowing large-scale commercial applications in the supply chain, ticketing, and asset tracking. The future of RFID, however, lies in the transition from traditional embedded applications to wearable intelligent systems, in which the tags are seamlessly integrated with everyday clothing. Augmented with various ambient and biochemical sensors, the tag is capable of detecting physical parameters of its environment and providing continuous monitoring of human vital signs. Tremendous amount of tagged entities establish an intelligent infrastructure that is personalized and tailored to the needs of each individual and ultimately, it recedes into the background of our daily life. Although wearable tags in intelligent systems have the enormous potential to revolutionize the quality of human life, the emerging wearable RFID applications introduce new challenges for designers developing efficient and sophisticated RFID systems. Traditional tag design parameters and solutions will no longer respond to the new requirements. Instead, the whole RF community must adopt new methods and unconventional approaches to achieve advanced wearable tags that are highly transparently integrated into our daily life. In this research work, an empirical as well as a theoretical approach is taken to address the above-mentioned wearable RFID tag challenges. Exploiting new analysis tools in combination with computational electromagnetics, a novel technique to model the human body in UHF applications for initiating the design of optimized wearable tags is developed. Further, fundamental unprecedented UHF characteristics of advanced wearable electronics materials – electro-textiles, are established. As an extremely important outcome of this research work, innovative optimization methodologies for the promotion of novel and advanced wearable UHF antennas are proposed. Particularly, it is evidenced that proper embroidery fabrication techniques have the great potential to realize wearable tag antennas exhibiting excellent RF performance and structural properties for the seamless integration with clothing. The kernel of this research work is the realization of a flexible and fully embroidered passive UHF RFID patch tag prototype achieving optimized performance in close vicinity of the high-permittivity and dissipative human body. Its performance may be considered as a benchmark for future wearable antenna designs. This shows that this research work outcome forms an important contribution to the state of the art and a milestone in the development towards wearable intelligence

Applications of Antenna Technology in Sensors

During the past few decades, information technologies have been evolving at a tremendous rate, causing profound changes to our world and to our ways of living. Emerging applications have opened u[ new routes and set new trends for antenna sensors. With the advent of the Internet of Things (IoT), the adaptation of antenna technologies for sensor and sensing applications has become more important. Now, the antennas must be reconfigurable, flexible, low profile, and low-cost, for applications from airborne and vehicles, to machine-to-machine, IoT, 5G, etc. This reprint aims to introduce and treat a series of advanced and emerging topics in the field of antenna sensors

Applications of Additive Manufacturing Technologies to Ambient Energy Harvesters for Microwave and Millimeter-Wave Autonomous Wireless Sensing Networks and 3D Packaging Integration

The objectives of my researches are developing new RF and mm-wave energy harvester topologies and realizing them with new additive manufacturing fabrication processes. The proposed energy harvester topologies are utilized to achieve energy-autonomous wireless sensing networks for 5G communication and IoT solutions. The developed additive manufacturing fabrication process is adopted to realize not only energy harvesters but also mm-wave IC packaging process. Ambient energy harvesting techniques collect ambient energy such as solar, RF, heat, and vibration and convert them into DC power sources to support the energy requirement of electronics. Since the energy is provided autonomously and constantly, maintenance or replacement for the batteries inside wireless electronics is not necessary resulting in enormous cost reduction. The researches of energy harvester focus on three categories, new topologies to enhance the performances, increased harvested power levels, and applied energy harvester to find new killer applications. This work proposes new designs and improvements in all three categories. Various proof-of-concept backscattered sensing systems with integrated RF energy harvesters for 5G and IoT applications are demonstrated. In this research, high-efficiency and broadband rectifiers are proposed to support high-performance rectifications as well as increase harvested energy. New topologies to utilize both DC and harmonics are demonstrated to increase the reading range of on-body wireless sensing networks. Furthermore, energy-autonomous microfluidic sensing systems are demonstrated to unleash the potential of microfluidic applications. 5G energy harvester is proposed and integrated inside the multi-layered additive manufacturing IC packages to achieve fully-functional SiP modules. While determining the fabrication methods, low-cost, fast-prototyping, and scalable methods with great material and structural flexibilities are preferable, and thus, additive manufacturing technologies including inkjet printing, 3D printing, and glass semi-additive patterning process are adopted. This research utilizes inkjet-printed masks, substrates, and metal traces to simplify the conventional fabrication process. The new low-loss inkjet-printable ink is developed to push the additive manufacturing technologies to mm-wave ranges. The flexible 3D-printed materials are characterized and used for wearable sensor designs, microfluidic channels, and flexible packaging topologies. The 3D features are included inside the IC packages to achieve high-performance multi-layer packaging structures with shorter lengths, lower loss, and smaller parasitics. The high-precision glass semi-additive patterning process is used to realized AiP and SiP designs with great performances. Furthermore, through combining inkjet and 3D printing, this work proposes a fast, cost-effective, scalable, and environmentally-friendly fabrication process for various high-performance and compact antenna designs, microwave/mm-wave components, microfluidic channels, RF energy harvesters, and SiP designs. In summary, this work utilizes additive manufacturing processes to realize various innovative topologies of energy harvesters to harvest more power and achieve higher rectification efficiency with smaller sizes. Additive manufacturing processes and energy harvesting techniques are also used to demonstrate new applications including the first on-body long-range sensing network, the first energy-autonomous long-range microfluidic sensing system, and the first fully-functional energy-autonomous 5G SiP module design. The proposed topologies are suitable for smart cities, smart skin, and IoT applications.Ph.D

Location and Map Awareness Technologies in Next Wireless Networks

In a future perspective, the need of mapping an unknown indoor environment, of localizing and retrieving information from objects with zero costs and efforts could be satisfied by the adoption of next 5G technologies. Thanks to the mix of mmW and massive arrays technologies, it will be possible to achieve a higher indoor localization accuracy without relying on a dedicated infrastructure for localization but exploiting that designed for communication purposes. Besides users localization and navigation objectives, mapping and thus, the capability of reconstructing indoor scenarios, will be an important field of research with the possibility of sharing environmental information via crowd-sourcing mechanisms between users. Finally, in the Internet of Things vision, it is expected that people, objects and devices will be interconnected to each other with the possibility of exchanging the acquired and estimated data including those regarding objects identification, positioning and mapping contents. To this end, the merge of RFID, WSN and UWB technologies has demonstrated to be a promising solution. Stimulated by this framework, this work describes different technological and signal processing approaches to ameliorate the localization capabilities and the user awareness about the environment. From one side, it has been focused on the study of the localization and mapping capabilities of multi-antenna systems based on 5G technologies considering different technological issues, as for example those related to the existing available massive arrays. From the other side, UWB-RFID systems relying on passive communication schemes have been investigated in terms of localization coverage and by developing different techniques to improve the accuracy even in presence of NLOS conditions

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

High-Efficiency Low-Voltage Rectifiers for Power Scavenging Systems

Abstract Rectifiers are commonly used in electrical energy conversion chains to transform the energy obtained from an AC signal source to a DC level. Conventional bridge and gate cross-coupled rectifier topologies are not sufficiently power efficient, particularly when input amplitudes are low. Depending on their rectifying element, their power efficiency is constrained by either the forward-bias voltage drop of a diode or the threshold voltage of a diode-connected MOS transistor. Advanced passive rectifiers use threshold cancellation techniques to effectively reduce the threshold voltage of MOS diodes. Active rectifiers use active circuits to control the conduction angle of low-loss MOS switches. In this thesis, an active rectifier with a gate cross-coupled topology is proposed, which replaces the diode-connected MOS transistors of a conventional rectifier with low-loss MOS switches. Using the inherent characteristics of MOS transistors as comparators, dynamic biasing of the bulks of main switches and small pull-up transistors, the proposed self-supplied active rectifier exhibits smaller voltage drop across the main switches leading to a higher power efficiency compared to conventional rectifier structures for a wide range of operating frequencies in the MHz range. Delivery of high load currents is another feature of the proposed rectifier. Using the bootstrapping technique, single- and double-reservoir based rectifiers are proposed. They present higher power and voltage conversion efficiencies compared to conventional rectifier structures. With a source amplitude of 3.3 V, when compared to the gate cross-coupled topology, the proposed active rectifier offers power and voltage conversion efficiencies improved by up to 10% and 16% respectively. The proposed rectifier using the bootstrap technique, including double- and single-reservoir schemes, are well suited for very low input amplitudes. They present power and voltage conversion efficiencies of 75% and 76% at input amplitude of 1.0 V and maintain their high efficiencies over input amplitudes greater than 1.0V. Single-reservoir bootstrap rectifier also reduces die area by 70% compared to its double-reservoir counterpart.---------Résumé Les redresseurs sont couramment utilisés dans de nombreux systèmes afin de transformer l'énergie électrique obtenue à partir d'une source alternative en une alimentation continue. Les topologies traditionnelles telles que les ponts de diodes et les redresseurs se servant de transistors à grilles croisées-couplées ne sont pas suffisamment efficaces en terme d’énergie, en particulier pour des signaux à faibles amplitudes. Dépendamment de leur élément de redressement, leur efficacité en termes de consommation d’énergie est limitée soit par la chute de tension de polarisation directe d'une diode, soit par la tension de seuil du transistor MOS. Les redresseurs passifs avancés utilisent une technique de conception pour réduire la tension de seuil des diodes MOS. Les redresseurs actifs utilisent des circuits actifs pour contrôler l'angle de conduction des commutateurs MOS à faible perte. Dans cette thèse, nous avons proposé un redresseur actif avec une topologie en grille croisée-couplée. Elle utilise des commutateurs MOS à faible perte à la place des transistors MOS connectés en diode comme redresseurs. Le circuit proposé utilise: des caractéristiques intrinsèques des transistors MOS pour les montages comparateurs et une polarisation dynamique des substrats des commutateurs principaux supportés par de petits transistors de rappel. Le redresseur proposé présente des faibles chutes de tension à travers le commutateur principal menant à une efficacité de puissance plus élevée par rapport aux structures d’un redresseur conventionnel pour une large gamme de fréquences de fonctionnement de l’ordre des MHz. La conduction des courants de charge élevée est une autre caractéristique du redresseur proposé. En utilisant la méthode de bootstrap, des redresseurs à simple et à double réservoir sont proposés. Ils présentent une efficacité de puissance et un rapport de conversion de tension élevés en comparaison avec les structures des redresseurs conventionnels. Avec une amplitude de source de 3,3 V, le redresseur proposé offre des efficacités de puissance et de conversion de tension améliorées par rapport au circuit à transistors croisés couplés. Ces améliorations atteignent 10% et 16% respectivement. Les redresseurs proposés utilisent la technique de bootstrap. Ils sont bien adaptés pour des amplitudes d'entrée très basses. À une amplitude d'entrée de 1,0 V, ces derniers redresseurs présentent des rendements de conversion de puissance et de tension de 75% et 76%. Le redresseur à simple réservoir réduit également l’aire de silicium requise de 70% par rapport à la version à double-réservoir

Efficient RF energy scavenging and ultra-low power management for powering wireless sensor nodes

As the demand for real-time information in engineering and health care systems keeps increasing, the need for wireless sensor nodes is also continuously increasing. As a result, the cost and effort involved in installing and maintaining batteries to power the numerous sensor nodes is growing exponentially. Providing a cost effective and maintenance free alternate energy source is the motivation behind the development of energy scavenging solutions for self-powered sensor networks. In this research, an energy scavenging system that extracts energy from ambient radio-frequency waves transmitted in the 2.4GHz ISM band is designed. The harvested energy is efficiently managed with an ultra low-power switched capacitor buck-boost DC-DC converter to wirelessly power the nodes in a wireless sensor network. Analysis and optimization of the number of rectifier stages required to achieve efficient power conversion is carried out. To improve far field conversion efficiency and extend the scavenger sensitivity, the threshold voltage of the diodes in the rectifiers are reduced to about 50mV by using the floating-gate programming technique.The active power consumption of the switched-capacitor DC-DC converter is around 1.2μW. A micro-power analog to digital converter for variable gain selection and a sub-threshold linear voltage regulator for providing the start-up, are designed. The integrated system provides a fully autonomous micro-energy scavenging solution for the sensor nodes. The simulated results suggest that the scavenger achieves a 10% higher con- version efficiency than the most recently reported work. The operational distance of this improved energy scavenging solution is 6 meters (in free space) from an intentional RF transmitter operating under FCC specifications at 2.4GHz. The targeted application of this research is to provide an alternate energy solution for low power devices, including wireless sensor nodes and bio-medical applications

Smart contract and web dapp for tracing sustainability indicators in the textile and clothing value chain

Mestrado em Engenharia Informática na Escola Superior de Tecnologia e Gestão do Instituto Politécnico de Viana do CasteloNa sociedade atual, o têxtil e vestuário é um dos maiores setores de mercado do mundo. O rápido crescimento desta indústria está a ter impactos sem precedentes na sustentabilidade do planeta, respondendo por consequências negativas ambientais, sociais e de saúde. As tendências da fast-fashion, juntamente com a falta de transparência na cadeia de valor têxtil global, somam-se a cenários desfavoráveis para o mundo, à medida que os níveis crescentes de poluição e consumo de recursos dentro da cadeia de valor atingem máximos históricos a cada ano que passa. O ciclo de vida de uma peça de roupa precisa de se adaptar a um modelo económico regenerativo em vez de linear, que acaba no equivalente a um caminhão de lixo de produtos têxteis sendo descartado num aterro sanitário a cada segundo [1]. Não só as indústrias precisam de reformular os seus processos para circularizar as suas cadeias de valor e promover ações sustentáveis, mas também os consumidores precisam de participar do processo de manter os produtos no círculo da cadeia de valor, pois cabe a eles decidir o destino final de um produto vestuário aquando o seu fim da vida útil. Com estas questões em mente, esta dissertação visa desenvolver duas soluções que possam mitigar os problemas a cima mencionados e promover ações sustentáveis rumo a uma economia circular na cadeia de valor do têxtil e vestuário. Uma solução business-to-business baseada em smart contracts do Hyperledger Fabric para gerir a cadeia de valor do têxtil e vestuário com funcionalidade de rastreabilidade foi desenvolvida como prova de conceito para apoiar as reivindicações de sustentabilidade dos participantes na cadeia de valor, da fibra à peça final de vestuário. A actual funcionabilidade de rastreabilidade desenvolvida no smart contract fornece aos operadores da cadeia de valor a capacidade de rastrear um lote até à sua origem, contudo, também limita a escalabilidade devido ao aumento exponencial do tamanho do bloco, especialmente se considerarmos uma cadeia de valor circular. Para os consumidores, foi proposta uma aplicação descentralizada business-to-consumer-to-consumer com elementos de eco-gamificação para promover o envolvimento e motivação do utilizador para a realização de tarefas que contribuam para a adoção de uma economia circular na cadeia de valor do têxtil e vestuário. Após testar a usabilidade da aplicação com o questionário AttrakDiff, concluiu-se que o sistema precisa de focar a sua usabilidade em prol de um produto orientado à tarefa em vez da orientação pessoal atual da aplicação a fim de promover ações que contribuam para a economia circular da cadeia de valor do têxtil e vestuário.In today’s society, Textile and Clothing (T&C) is one of the biggest market sectors world wide.The sheer size and fast growth of this industry is having unprecedented impacts on sustainability, accounting for negative environmental, social and health consequences. The fast-fashion trends along side the lack of transparency in the global T&C value chain add up to unfavorable scenarios for the world as the increas- ing levels of pollution and resource consumption within the value chain reach historic highs with every year that passes. The lifecycle of a clothing item needs to adapt to a regenerative economic model instead of a linear one that ends up in the equivalent of a garbage truck full of textiles being disposed into a landfill every second [1]. Not only do the industries need to revamp their processes to circularize their value chains and promote sustainable actions, but the consumers also need to partake in the process of keeping the products in the value chain loop as it is up to them to make the final decision upon the end-of-life of an item of clothing. With these issues in mind,this dissertation aims to develop two solutions that can mitigate the aforementioned problems and promote sustainable actions towards a circular economy in the T&C value chain. A Proof-of-Concept (PoC) Business-to-Business (B2B) T&C value chainmanagement smart contract solution builton Hyperledger Fabric with traceability features was developed to support the sustainability claims of participants in the value chain, from fiber to garment. The current traceability feature developed into the smart contract provides value chain operators the capabilities to trace a batch back to its origin, however, it also constraints scalability due to the exponential in crease in block size specially if considering a circular value chain. For the consumers, a Business-to-Consumer-to-Consumer (B2C2C) Decentralized Application (DApp) was proposed with eco-gamification elements fo rpromoting the user’s engagement and motivation to complete tasks that contribute for the adoption of a circular economy in the T&C value chain. After testing the consumer DApp’s usability with the AttrakDiff survey, it was concluded that the system needs to focus it susability towards a task-oriented product instead of the current self-oriented results in order to promote actions that contribute to the circular economy of the T&C value chain