New Approaches For Augmented UHF RFID Textile Yarn

International audienc

New Approaches For Augmented UHF RFID Textile Yarn

International audienc

UHF RFID Elastic Textile Yarn

International audienceOver the last decade, the wearable electronics has greatly improved and the wearables market is expected to increase exponentially in the next years. UHF (Ultra High Frequencies) RFID (Radio Frequency IDentification) textile yarns represent one of the most relevant solutions for adding smart functionality into clothes and more generally for any object integrating a textile tag. Among the existing textile yarn solutions, the E-Thread® technology consists on electronics embedded into textile yarn using a micro-encapsulation method. This technology is the starting point of the work presented in this paper. One of the hardest constraints that the RFID yarn should overcome is the robustness against stretching. Thus, the antenna has to be tolerant to the deformation of the associated textile yarn. Unlike the half-wave dipole antenna used in the current E-Thread® yarn, the proposed solution is based on helical dipole antenna topology because its geometry naturally makes feasible an axial stretching. This study details the manufacturing process as well as the design methodology of the antenna taking into account the RFID context as well as the constraints imposed by the manufacturing process. The impact of the antenna's physical parameters is highlighted in order to provide design guidelines. The helical dipole antenna enables until 16% of axial elongation while the dipole antenna would tear apart

Lightweight and Flexible Textile Metasurfaces and Array Antennas via Flat-Knitting

Metasurfaces are a class of electromagnetic devices that shape an outgoing wavefront to realize desired device functionalities. The predominant majority of current generation metasurfaces are compact, planar rigid devices that aim to replace traditional bulk optical components and radio-frequency antennae. The development of lightweight and flexible metasurfaces could enable new classes of conformal metasurfaces that can be used to cover non-planar surfaces in applications such as wearable antennas or carpet cloaks and also help further reduce the weight of existing planar rigid devices and enable easy stowage of very large aperture devices, possibly leading to a new class of lightweight, easily stowable and deployable devices, useful in both terrestrial and space-based communications and sensing applications. Textiles represent an interesting platform for lightweight and flexible metasurfaces. Leveraging highly-established fabric production techniques such as knitting, weaving, and embroidery could enable the production of relatively cheap, flexible devices on an industrial scale. Knitting, in particular, represents a highly-established and highly-flexible fabric production technique capable of engineering the shape and mechanical properties of the fabric alongside the fabric's electromagnetic response via patterning the fabric with metallic antenna archetypes. The works presented in this thesis aim to demonstrate novel designs and means to fabricate flexible, lightweight metasurfaces and array antennas that rely on scalable, established production techniques and commercially available materials. Further aims of this thesis are to provide a detailed account of the fabrication, design, and performance of textile metasurfaces and array antennas and provide limited commentary on the commercial prospects, limitations, and fabrication demands of the works presented herein. The first works detailed in this thesis concern a novel type of lightweight and flexible metasurface produced via flat-knitting using float-jacquard colorwork knitting to pattern the fabric with an array of antenna archetypes. This includes novel demonstrations of a textile metalens and textile metasurface vortex beam generator capable of producing, respectively, focused or collimated Gaussian and vortex beams, albeit with low efficiency. Detailed modeling and analysis of the structure of the float-jacquard knit flexible metasurfaces identify a key cause of the degraded performance of these devices, the irregular float geometry, in particular contact between metallic floats that give rise to a strong specular reflection, offering insight into future avenues for further optimization. The second work detailed in this thesis concerns a flat-knit flexible array antenna consisting of four Yagi-Uda antennas. A different colorwork knitting approach, intarsia knitting, is used to pattern the antenna elements into the fabric. The intarsia knit flexible array antenna performs comparably to other flexible end-fire antennas with a gain of 6.94 dB and forward-to-backward power ratio of 9.25 dB, offering a compelling platform for small arrays of flexible antennas, which can be integrated into wearable garments and textiles. The final work detailed in this thesis concerns another flat-knit flexible metasurface, a metalens, knit using intarsia colorwork. The intarsia knit metasurface has a peak focusing efficiency of 47.46%, and, when oriented as reflectarray, a peak gain of 24.71 dB. The large aperture intarsia knit flexible metasurfaces demonstrate comparable performance to existing flexible metasurfaces, making them far more suitable for commercial applications, albeit with higher fabrication demands than float-jacquard knit devices

Printed Spiral Coil Design, Implementation, And Optimization For 13.56 MHz Near-Field Wireless Resistive Analog Passive (WRAP) Sensors

Noroozi, Babak. Ph.D. The University of Memphis. June 2020. Printed Spiral Coil Design, Implementation, and Optimization for 13.56 MHz Near-Field Wireless Resistive Analog Passive (WRAP) Sensors. Major Professor: Dr. Bashir I. Morshed.Monitoring the bio-signals in the regular daily activities for a long time can embrace many benefits for the patients, caregivers, and healthcare system. Early diagnosis of diseases prior to the onset of serious symptoms gives more time to take some preventive action and to begin effective treatment with lower cost. These health and economy benefits are achievable with a user-friendly, low-cost, and unobtrusive wearable sensor that can easily be carried by a patient with no interference with the normal life. The easy application of such sensor brings the smart and connected community (SCC) idea to existence. The spread of a designated disease, like COVID-19, can be studied by collecting the physiological signals transmitted from the wearable sensors in conjunction with a mobile app interface. Moreover, such a comfortable wearable sensor can help to monitor the vital signals during fitness activities for workout concerns. The desire of such wearable sensor has been responded in many researches and commercial products such as smart watch and Fitbit. Wireless connection between the sensor on the body and the scanner is the key and common factor of all convenient wearables. This essential feature has been currently addressed by the costly techniques which is the main impediment to be widely applicable. The existing wireless methods including WiFi, Bluetooth, RFID, and NFC impose cost, complexity, weight, and extra maintenance including battery replacement or recharging, which drove us to propose a low-cost, convenient, and simple technique for wireless connection suitable for battery-less fully-passive sensors. Using a pair of coils connected by the near-field magnetic induction has been copiously used in wireless power transfer (WPT) for medical and industrial applications. However, near field RFID and NFC rely on this technique with active circuits. In contrast, we have proposed a wireless resistive analog passive (WRAP) sensor in which a resistive transducer at the secondary side, affects the primary quality factor (Q) through the inductive connection between a pair of square-shaped Printed Spiral Coils (PSC). The primary 13.56 MHz (ISM band) signal is modulated in response to the continuous change of bio-signal and the amount of response to the unit change in transducer resistance is defined as sensitivity. A higher sensitivity enables the system to respond to the smaller bio-signals and increases the coils maximum relative mobilities. The PSCs specifications and circuit components determine the sensitivity and its tolerance to the coils displacements. We first define and formulize the objective function for coil and components optimization to achieve the maximum sensitivity. Although the optimization methods do not show much different results, due to the speed and simplicity, the Genetic Algorithm (GA) technique is chosen as an advanced method. Then in second optimization stage, the axial and lateral distances that affect the mutual inductance are introduced to the optimization process. The results as a pair of PSCs profiles and the associated circuit components are obtained and fabricated that produced the maximum sensitivity and misalignment tolerance. For the sake of patient comfort, the secondary coil size is fixed at 20 mm and the primary coil is optimized at 60 mm with the maximum (normalized) sensitivity 1.3 m for 16 mm axial distance. If the Read-Zone is defined as the space in which the center of secondary coil can move and the sensitivity keeps at least half of its maximum value, the best Read-Zone has a conical shape with the base radius 22.5 mm and height 14 mm. The analytical results are verified by the measurement results on the fabricated coils and circuits

Evaluation of conductive threads for optimizing performance of embroidered RFID antennas

Radio frequency identification (RFID) refers to a technology that utilizes radio signals for identifying objects automatically. This technology consists of a reader that detects the objects and a transponder that gets attached to the object and it is called tag. The tag is an enclosure that houses the antenna and an IC that stores the necessary information on that object. This thesis focuses tag antennas made for embroidered RFID. Embroidered antennas are made by sewing antenna using conductive thread onto a fabric using a computerized sewing machine. This enables us to extend the field of RFID technologies to textiles. Conventional RFID systems that use metal conductors are easy to model but the same cannot be said for embroidered RFID. The reason being conductive threads and embroidered antennas don’t have definite conductivity. The conductivity of an embroidered antenna depends multiple factors like thread conductivity, thread density, stitch density, sewing pattern etc. The target of this thesis is experimenting with conductive threads physically and for their conductivity followed by eval-uating them for the use of embroidered RFID antenna fabrication for optimizing the perfor-mance. In this thesis, using same antenna pattern and technique, tags were fabricated from 6 differ-ent conductive threads onto the same cotton fabric. The conductive threads were investigated for their conductivity, thread thickness and their strength. The antennas were tested for their read range and the effect of different threads on the antenna were analysed. The threads with the highest conductive nature gave the highest read range of 6.2 meters. The threads were also evaluated for their usability for embroidery. Some threads were too thick, some had exposed structures leading to malfunction in the sewing machine and others were too thin and ripped easily during sewing. The selected thread should not only have great performance, but also it needs to be practical. It is seen that the conductivity of antenna and hence the performance is easily improved with using high conductive thread. After taking all the factors into account, finally a thread was selected that can be used to make high performance embroidered RFID antennas and also highly suitable for embroidery process. In the future, the same work can be revisited or extended to other more versatile and higher conductivity threads. Also, the advancement is embroidery techniques will allow for more con-ductive threads to be compatible for embroidery opening more options for optimization

The Design, Fabrication and Practical Evaluation of Body-centric Passive RFID Platforms

Passive ultra-high-frequency (UHF) radio-frequency identification (RFID) technology is increasingly being recognized as a compelling approach to utilizing energy- and costefficient wireless platforms for a wireless body area network (WBAN). The development of WBANs has stimulated a lot of research over recent years, as they can offer remarkable benefits for the healthcare and welfare sectors, as well as having innovative sportsrelated applications.This thesis is to evaluate and develop the RFID tags used in an integrated wearable RFID platform working in a realistic environment. Each of the wearable antennas were specifically designed for a target part of the body, such as the back or the hand. The antennas were manufactured in different ways, using copper tape, electro-textiles (Etextile) and embroidered conductive threads. After they had been produced, the tags were subjected to on-body measurement and reliability tests. The reliability tests were performed under tough conditions in which the tags were stretched, for instance, or exposed to high humidity and washing. Our results show that the tags can perform well when worn on-body in a harsh environment.This thesis provides several integrated solutions for wireless wearable devices. By different RFID antenna design and fabrication methods, the RFID tag can be used as the moisture and strain sensor with lightweight, small size, flexible pattern and great dailyuse reliability

Integration of conductive materials with textile structures : an overview

In the last three decades, the development of new kinds of textiles, so-called smart and interactive textiles, has continued unabated. Smart textile materials and their applications are set to drastically boom as the demand for these textiles has been increasing by the emergence of new fibers, new fabrics, and innovative processing technologies. Moreover, people are eagerly demanding washable, flexible, lightweight, and robust e-textiles. These features depend on the properties of the starting material, the post-treatment, and the integration techniques. In this work, a comprehensive review has been conducted on the integration techniques of conductive materials in and onto a textile structure. The review showed that an e-textile can be developed by applying a conductive component on the surface of a textile substrate via plating, printing, coating, and other surface techniques, or by producing a textile substrate from metals and inherently conductive polymers via the creation of fibers and construction of yarns and fabrics with these. In addition, conductive filament fibers or yarns can be also integrated into conventional textile substrates during the fabrication like braiding, weaving, and knitting or as a post-fabrication of the textile fabric via embroidering. Additionally, layer-by-layer 3D printing of the entire smart textile components is possible, and the concept of 4D could play a significant role in advancing the status of smart textiles to a new level