Towards Accurate Dielectric Property Retrieval of Biological Tissues for Blood Glucose Monitoring

(c) 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.This post-acceptance version of the paper is essentially complete, but may differ from the official copy of record, which can be found at the following web location (subscription required to access full paper): http://dx.doi.org/10/1109/TMTT.2014.2365019

A Recent Approach towards Fluidic Microstrip Devices and Gas Sensors: A Review

This paper aims to review some of the available tunable devices with emphasis on the techniques employed, fabrications, merits, and demerits of each technique. In the era of fluidic microstrip communication devices, versatility and stability have become key features of microfluidic devices. These fluidic devices allow advanced fabrication techniques such as 3D printing, spraying, or injecting the conductive fluid on the flexible/rigid substrate. Fluidic techniques are used either in the form of loading components, switching, or as the radiating/conducting path of a microwave component such as liquid metals. The major benefits and drawbacks of each technology are also emphasized. In this review, there is a brief discussion of the most widely used microfluidic materials, their novel fabrication/patterning methods

Analysis and design of antennas and radiometers for radio astronomy applications in microwave, Mm-wave, and THz Bands

Mención Internacional en el título de doctorWe are living in interesting times for astronomy science, since the birth of the radio astronomy field in the 20th century by Karl Jansky, the availability of new and better radio astronomy receivers is in increasing demand to push the human understanding of the universe. In this thesis, various components (antennas, baluns, antenna-arrays, and radiometers) are proposed for radio astronomy receivers. The proposed designs are belonging to three receiver topologies (direct detection, down-conversion, and up-conversion) that operate at different frequency bands from MHz up to a few of THz. Also, to demonstrate that the same proposed design is capable of working efficiently at different operating frequencies, multiple adjusted designs are presented for several practical radio astronomy and space applications. Firstly, a receiver based on the direct detection of the Electromagnetic (EM) radiation through a radio telescope working on cryogenic cooling conditions. In this part, the focus is on designing conical log-spiral antennas and baluns (balanced to unbalanced transformers) to be used as feeds for VLBI Global Observing System (VGOS) ground-based radio telescopes. The feeds cover the Ultrawideband (UWB) from 2 GHz to 14 GHz with Circular Polarization (CP) radiation and stable radiation patterns. After integration of the feeds to the radio telescope, the whole system operates with high aperture efficiency and high System Equivalent Flux Density (SEFD) over the whole required wide range. The fabrication, assembly, and measurements for single-element and four-elements array are provided for achieving the requirements for single CP and dual CP operation. Also, in the same first part, the proposed single-element feed (antenna + balun) is readjusted for being used for CryoRad spaceborne Earth observations. This feed has a single CP over low-frequency UWB from 400MHz to 2 GHz with low weight and physical size compared to standard horn feeds. The second part of the thesis is dedicated to a THz source to be used as a local oscillator for heterodyne radio astronomy THz receivers in which the down-conversion of the THz radiation to a lower frequency occurs. The source is based on an array of self-complementary bow-tie antennas and photomixers that lies on a dielectric lens. The source can be scaled easily to cover different UWB ranges, three ranges are analyzed from 200 GHz to 2 THz, 100 GHz to 1 THz, and 50 GHz to 0.5 THz. Additionally, in this part, a complete study for the effects of metal losses on such THz planar antennas is performed which are not well-investigated in literature yet, the physical explanations behind such effects are also provided. Although these proposed THz sources themselves can work at room temperature, the receiver probably still needs the cooling for the other receiver components (such as the mixer) to work efficiently at such high frequencies. This is the motivation for the third part of this thesis which presents a different type of radio astronomy receiver that is completely able to work without cooling. The third receiver is based on the nonlinear up-converting of the microwave radiation into the optical domain using Whispering Gallery Mode (WGM) resonators which can work at room temperature efficiently. For such advantage and since this concept is naturally narrow-band, it can be a proper candidate for Cosmic Microwave Background (CMB) spectroscopy and space applications. The system design and its performance are analyzed for Ku band at 12 GHz with proposing a novel microwave coupling scheme for enhancing the up-conversion photonic efficiency which is the main limitation for such upconversion systems. Likewise, several high gain 3D-printed Dielectric Resonator Antenna (DRA)s are proposed in both isolated and array configurations to have a direct coupling of the microwave radiation to the proposed scheme. Another practical application for such receiver is presented for CubeSat missions at the mm-wave band (183 GHz) for climate change forecasting. It is clear here that removing the cryogenic cooling conditions decreases satellite weight and cost, which in turn significantly increases its lifetime. Also, it is worth noting that besides the radio astronomy applications, the proposed receivers (and/or their antenna/components) can be used for many other applications. For example, the UWB antennas in the first part can be used as wideband scalable probes for EM compatibility testing or other wireless systems that require single or dual CP such as radar and military applications. This is because the solutions provide constant beam characteristics with good CP polarization purity and stable performance over the operating UWB. In the same way, the proposed THz source in the second part can be used in several THz applications such as very high-speed wireless communications, highresolution imaging for medical and security purposes. This is because of its key benefits as decade bandwidth, compact size, low noise, low power demand, high tunability, and the ability to work at room temperature. For the up-conversion scheme proposed in the third part, due to its high photonic efficiency, low noise level which enables it to work at room temperature, and its scalability from a few GHz up to several THz, it is suitable for low-cost and high sensitivity applications. Specifically, the ones that need to get rid of the hard cryogenic cooling conditions, or at least, relax them and allow the system to work efficiently at higher temperatures. For instance, portable mm-wave and THz systems for quality control, security, and biochemistry. Finally, in this part, the proposed DRA elements and arrays, due to their low cost, high gain, and low losses, can be used for sensing applications and 5G base station antennas.Programa de Doctorado en Multimedia y Comunicaciones por la Universidad Carlos III de Madrid y la Universidad Rey Juan CarlosPresidente: Raed Shubair.- Secretario: Adrián Amor Martín.- Vocal: José Manuel Fernández Gonzále

Metamaterials Application in Sensing

Metamaterials are artificial media structured on a size scale smaller than wavelength of external stimuli, and they can exhibit a strong localization and enhancement of fields, which may provide novel tools to significantly enhance the sensitivity and resolution of sensors, and open new degrees of freedom in sensing design aspect. This paper mainly presents the recent progress concerning metamaterials-based sensing, and detailedly reviews the principle, detecting process and sensitivity of three distinct types of sensors based on metamaterials, as well as their challenges and prospects. Moreover, the design guidelines for each sensor and its performance are compared and summarized

Wideband and UWB antennas for wireless applications. A comprehensive review

A comprehensive review concerning the geometry, the manufacturing technologies, the materials, and the numerical techniques, adopted for the analysis and design of wideband and ultrawideband (UWB) antennas for wireless applications, is presented. Planar, printed, dielectric, and wearable antennas, achievable on laminate (rigid and flexible), and textile dielectric substrates are taken into account. The performances of small, low-profile, and dielectric resonator antennas are illustrated paying particular attention to the application areas concerning portable devices (mobile phones, tablets, glasses, laptops, wearable computers, etc.) and radio base stations. This information provides a guidance to the selection of the different antenna geometries in terms of bandwidth, gain, field polarization, time-domain response, dimensions, and materials useful for their realization and integration in modern communication systems

Design de circuitos RFID multi-ressonantes sem chip como substitutos dos códigos de barras

The chipless RFID technology , appears from an e ort to design low-cost RFID tags without the use of traditional silicone Application Specific Integrated Circuits (ASICs) that are the price bottleneck of the typicall RFID technology. In this way, tags become fully passive and without any active processing unit, thus the Chipless RFID system have more similarities with the Radio Detection And Ranging (RADAR) systems than with the common RFID systems. This dissertation sheds light on the problems and challenges that the RFID technology has as replacement of the optical barcode labels, discuss the state of the art of the chipless RFID technology and presents a model to describe the relationship between the multi-resonant circuit resonant frequency and the resonant spirals length. Finally, a chipless RFID system is simulated making use of the fractional Fourier Transform as means to separate linear frequency modulated signals that collide in both time and frequency domain. The results achieved with dissertation not only aid designers with the synthesis of multi-resonant circuits but also prove the reliability of the use of the fractional Fourier Transform as a means of manipulating the time-frequency domain and successfully recovering individual tags' ID from a signal containing more than one collided backscattered signal.A tecnologia de RFID sem chip, surgiu de um esforço para obter etiquetas RFID de baixo custo sem o uso de circuitos integrados de aplicação especifica (ASICs) que são a restrição à diminuição dos preço dos tipicos sistemas RFID. Desta forma, as tags tornam-se totalmente passivas e sem nenhuma unidade de processamento ativa, passando, os sistemas RFID sem chip a ter mais semelhanças com os sistemas de Radio Detection And Ranging (RADAR) do que com os sistemas RFID comuns. Esta dissertação esclarece os problemas e desafios que a tecnologia RFID enfrenta enquanto substituta das etiquetas de código de barras apresentando também o estado da arte da tecnologia RFID sem chip. Também apresenta e propõe um modelo para descrever a relação entre a frequência de ressonância do circuito multi-ressonante e o comprimento das espirais ressonantes. Finalmente, um sistema RFID sem chip é simulado usando a transformada fracionária de Fourier como meio de separar sinais modulados linearmente em frequência que colidem simultaneamente no domínio do tempo e da frequência. Os resultados alcançados com esta dissertação por um lado ajudam os projetistas com a síntese de circuitos multi-ressonantes e por outro provam a confiabilidade do uso da transformada fracionária de Fourier como um meio de manipular o domínio tempo-frequência para recuperar com sucesso informa ção individual de ID a partir de um sinal que contém mais de um sinal transmistido de uma etiqueta sem chip.Mestrado em Engenharia Eletrónica e Telecomunicaçõe

A Novel Power-Efficient Wireless Multi-channel Recording System for the Telemonitoring of Electroencephalography (EEG)

This research introduces the development of a novel EEG recording system that is modular, batteryless, and wireless (untethered) with the supporting theoretical foundation in wireless communications and related design elements and circuitry. Its modular construct overcomes the EEG scaling problem and makes it easier for reconfiguring the hardware design in terms of the number and placement of electrodes and type of standard EEG system contemplated for use. In this development, portability, lightweight, and applicability to other clinical applications that rely on EEG data are sought. Due to printer tolerance, the 3D printed cap consists of 61 electrode placements. This recording capacity can however extend from 21 (as in the international 10-20 systems) up to 61 EEG channels at sample rates ranging from 250 to 1000 Hz and the transfer of the raw EEG signal using a standard allocated frequency as a data carrier. The main objectives of this dissertation are to (1) eliminate the need for heavy mounted batteries, (2) overcome the requirement for bulky power systems, and (3) avoid the use of data cables to untether the EEG system from the subject for a more practical and less restrictive setting. Unpredictability and temporal variations of the EEG input make developing a battery-free and cable-free EEG reading device challenging. Professional high-quality and high-resolution analog front ends are required to capture non-stationary EEG signals at microvolt levels. The primary components of the proposed setup are the wireless power transmission unit, which consists of a power amplifier, highly efficient resonant-inductive link, rectification, regulation, and power management units, as well as the analog front end, which consists of an analog to digital converter, pre-amplification unit, filtering unit, host microprocessor, and the wireless communication unit. These must all be compatible with the rest of the system and must use the least amount of power possible while minimizing the presence of noise and the attenuation of the recorded signal A highly efficient resonant-inductive coupling link is developed to decrease power transmission dissipation. Magnetized materials were utilized to steer electromagnetic flux and decrease route and medium loss while transmitting the required energy with low dissipation. Signal pre-amplification is handled by the front-end active electrodes. Standard bio-amplifier design approaches are combined to accomplish this purpose, and a thorough investigation of the optimum ADC, microcontroller, and transceiver units has been carried out. We can minimize overall system weight and power consumption by employing battery-less and cable-free EEG readout system designs, consequently giving patients more comfort and freedom of movement. Similarly, the solutions are designed to match the performance of medical-grade equipment. The captured electrical impulses using the proposed setup can be stored for various uses, including classification, prediction, 3D source localization, and for monitoring and diagnosing different brain disorders. All the proposed designs and supporting mathematical derivations were validated through empirical and software-simulated experiments. Many of the proposed designs, including the 3D head cap, the wireless power transmission unit, and the pre-amplification unit, are already fabricated, and the schematic circuits and simulation results were based on Spice, Altium, and high-frequency structure simulator (HFSS) software. The fully integrated head cap to be fabricated would require embedding the active electrodes into the 3D headset and applying current technological advances to miniaturize some of the design elements developed in this dissertation

Ultra Wideband

Ultra wideband (UWB) has advanced and merged as a technology, and many more people are aware of the potential for this exciting technology. The current UWB field is changing rapidly with new techniques and ideas where several issues are involved in developing the systems. Among UWB system design, the UWB RF transceiver and UWB antenna are the key components. Recently, a considerable amount of researches has been devoted to the development of the UWB RF transceiver and antenna for its enabling high data transmission rates and low power consumption. Our book attempts to present current and emerging trends in-research and development of UWB systems as well as future expectations

Wearable RF sensors for non-invasive detection of blood-glucose levels

PhDRadio frequency (RF) techniques have the potential to provide blood glucose readings through sensing the glucose dependent change in dielectric properties of the biological tissue. Such technique can enable much desired non-invasive and continuous monitoring of blood glucose level. In this work, we present realistic glucose dependence of dielectric properties as well as basic understanding of resonator behaviour while radiating towards the lossy biological tissue. To investigate the potential of RF techniques, two resonators, operating at microwave frequencies when placed radiating towards the biological tissue, are designed and fabricated. The spiral resonator is tested with liquid and semi-solid phantoms containing different amounts of sugar. An analytical formulation to retrieve the dielectric properties of the biological tissues is improved. In order to perform realistic tests, novel tissue mimicking materials for an extremely wide frequency range are proposed. Glucose dependance of the blood mimicking material dielectric properties are further investigated by adding realistic glucose amounts to the blood mimicking material and dielectric spectroscopy is performed. Next, a single pole Cole-Cole model is fitted to the median of the dielectric property measurements. In addition, a patch resonator is simulated with four-layered digital phantom and tested with the four-layered physical tissue mimicking phantom. Finally, a double parameter measurement platform is constructed by combining the patch resonator and a commercial force sensor to perform controlled experiments with humans. Also, the force dependant response of the patch resonator is quantified. Soda tests is performed on five subjects with the platform, all subjects were asked to apply the same level of force. Spiral resonator is also applied to examine the glucose changes of two human subjects during the soda test. The results suggests that, although the glucose-dependance of the dielectric properties is relatively small, the input impedance of a microwave resonator is still sensitive to such small alterations

Foldable all-textile cavity-backed slot antennas for personal UWB localization

An all-textile multimoded cavity-backed slot antenna has been designed and fabricated for body-worn impulse radio ultra-wideband (IR-UWB) operation in the 3,744-4,742.4 MHz frequency band, thereby covering Channels 2 and 3 of the IEEE 802.15.4a standard. Its light weight, mechanical flexibility, and small footprint of 35 mm x 56 mm facilitate integration into textile for radio communication equipment for first aid responders, personal locator beacons, and equipment for localization and medical monitoring of children or the elderly. The antenna features a stable radiation pattern and reflection coefficient in diverse operating conditions such as in free space, when subject to diverse bending radii and when deployed on the torso or upper right arm of a test person. The high isolation toward the wearer's body originates from the antenna's hemispherical radiation pattern with a -3 dB beamwidth of 120 degrees and a front-to-back ratio higher than 11 dB over the entire band. Moreover, the antenna exhibits a measured maximum gain higher than 6.3 dBi and a radiation efficiency over 75%. In addition, orientation-specific pulse distortion introduced by the antenna element is analyzed by means of the System Fidelity Factor (SFF). The SFF of the communication link between two instances of this antenna is higher than 94% for all directions within the antenna's -3 dB beamwidth. This easily wearable and deployable antenna is suitable to support IR-UWB localization with an accuracy in the order of 5 cm