336 research outputs found

    3-D printed UWB microwave bodyscope for biomedical measurements

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    © 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, 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 component of this work in other works.In this letter, a three-dimensional (3-D) printed compact ultrawideband (UWB) extended gap ridge horn (EGRH) antenna designed to be used for biological measurements of the human body is described. The operational frequency covers the microwave band of interest from 0.5 to 3.0 GHz (for an S 11 under -7 dB). The 3-D printed EGRH antenna is dielectrically matched to the permittivity of the human body, and because of its compactness, it can be visualized as a general-purpose microwave probe among the RF biomedical community. The probe has proven its capability as a pass-through propagation sensor for different parts of the human body and as a sensor detecting a 1 cm diameter object placed inside an artificial head phantom.Peer ReviewedPostprint (author's final draft

    Experimental Analysis on Effectiveness of Confocal Algorithm for Radar Based Breast Cancer Detection

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    Breast cancer is one of the most commonly diagnosed cancers in females in UK [1]. Early breast cancer detection which has recently been gaining a lot of consideration within the research community and the most important for a quick and effective treatment of the cancer is early detection. UWB radar based microwave imaging for early breast cancer detection is one of the most promising and attractive screening techniques currently under research. This technique offers several advantages such as low cost, better patient comfort, non-ionising and non-invasive radiation compared to X-Ray mammography. In this technique the breast is illuminated from various points with short UWB microwave pulse(s) and the collected backscattered energy is then processed to identify the presence and location of the tumour. In this thesis experimental measurement of the reflection coefficient in complex frequency domain is obtained from Vector Network Analyzer (VNA E5071) when the antenna is exposed to the environment and when the antenna is exposed to breast phantom. The tumor is simulated with different materials to investigate the effectiveness of the Confocal Microwave Imaging Algorithm for breast cancer detection. In addition, we used the materials at different depths to determine the effect of antenna distance to that of the tumor response. The Confocal Microwave Imaging (CMI) Algorithm for breast cancer detection is an easy and robust technique for tumor detection, which is used to approximate the precise location of the tumor. CMI is based on illuminating the breast with the UWB pulse from different antenna locations. The relative arrival times & amplitudes of the backscatter signals is used to estimate the location of the tumor. We applied the Confocal Algorithm in this study to the numerical data generated with the VNA and analyzed the results with different material(s) as tumor at different depth to verify its ability to estimate a tumor response

    High-performance wireless interface for implant-to-air communications

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    Nous élaborons une interface cerveau-machine (ICM) entièrement sans fil afin de fournir un système de liaison directe entre le cerveau et les périphériques externes, permettant l’enregistrement et la stimulation du cerveau pour une utilisation permanente. Au cours de cette thèse, nous explorons la modélisation de canal, les antennes implantées et portables en tant que propagateurs appropriés pour cette application, la conception du nouveau système d’un émetteur-récepteur UWB implantable, la conception niveau système du circuit et sa mise en oeuvre par un procédé CMOS TSMC 0.18 um. En plus, en collaboration avec Université McGill, nous avons conçu un réseau de seize antennes pour une détection du cancer du sein à l’aide d’hyperfréquences. Notre première contribution calcule la caractérisation de canal de liaison sans fil UWB d’implant à l’air, l’absorption spécifique moyennée (ASAR), et les lignes directrices de la FCC sur la densité spectrale de puissance UWB transmis. La connaissance du comportement du canal est nécessaire pour déterminer la puissance maximale permise à 1) respecter les lignes directrices ANSI pour éviter des dommages aux tissus et 2) respecter les lignes directrices de la FCC sur les transmissions non autorisées. Nous avons recours à un modèle réaliste du canal biologique afin de concevoir les antennes pour l’émetteur implanté et le récepteur externe. Le placement des antennes est examiné avec deux scénarios contrastés ayant des contraintés de puissance. La performance du système au sein des tissus biologiques est examinée par l’intermédiaire des simulations et des expériences. Notre deuxième contribution est dédiée à la conception des antennes simples et à double polarisation pour les systèmes d’enregistrement neural sans fil à bande ultra-large en utilisant un modèle multicouches inhomogène de la tête humaine. Les antennes fabriquées à partir de matériaux flexibles sont plus facilement adaptées à l’implantation ; nous étudions des matériaux à la fois flexibles et rigides et examinons des compromis de performance. Les antennes proposées sont conçues pour fonctionner dans une plage de fréquence de 2-11 GHz (ayant S11-dessous de -10 dB) couvrant à la fois la bande 2.45 GHz (ISM) et la bande UWB 3.1-10.6 GHz. Des mesures confirment les résultats de simulation et montrent que les antennes flexibles ont peu de dégradation des performances en raison des effets de flexion (en termes de correspondance d’impédance). Finalement, une comparaison est réalisée entre quatre antennes implantables, couvrant la gamme 2-11 GHz : 1) une rigide, à la polarisation simple, 2) une rigide, à double polarisation, 3) une flexible, à simple polarisation et 4) une flexible, à double polarisation. Dans tous les cas une antenne rigide est utilisée à l’extérieur du corps, avec une polarisation appropriée. Plusieurs avantages ont été confirmés pour les antennes à la polarisation double : 1) une taille plus petite, 2) la sensibilité plus faible aux désalignements angulaires, et 3) une plus grande fidélité. Notre troisième contribution fournit la conception niveau système de l’architecture de communication sans fil pour les systèmes implantés qui stimulent simultanément les neurones et enregistrent les réponses de neurones. Cette architecture prend en charge un grand nombre d’électrodes (> 500), fournissant 100 Mb/s pour des signaux de stimulation de liaison descendante, et Gb/s pour les enregistrements de neurones de liaison montante. Nous proposons une architecture d’émetteur-récepteur qui partage une antenne ultra large bande, un émetteur-récepteur simplifié, travaillant en duplex intégral sur les deux bandes, et un nouveau formeur d’impulsions pour la liaison montante du Gb/s soutenant plusieurs formats de modulation. Nous présentons une démonstration expérimentale d’ex vivo de l’architecture en utilisant des composants discrets pour la réalisation les taux Gb/s en liaison montante. Une bonne performance de taux d’erreur de bit sur un canal biologique à 0,5, 1 et 2 Gb/s des débits de données pour la télémétrie de liaison montante (UWB) et 100 Mb/s pour la télémétrie en liaison descendante (bande 2.45 GHz) est atteinte. Notre quatrième contribution présente la conception au niveau du circuit d’un dispositif d’émission en duplex total qui est présentée dans notre troisième contribution. Ce dispositif d’émission en duplex total soutient les applications d’interfaçage neural multimodal et en haute densité (les canaux de stimulant et d’enregistrement) avec des débits de données asymétriques. L’émetteur (TX) et le récepteur (RX) partagent une seule antenne pour réduire la taille de l’implant. Le TX utilise impulse radio ultra-wide band (IR-UWB) basé sur une approche alliant des bords, et le RX utilise un nouveau 2.4 GHz récepteur on-off keying (OOK).Une bonne isolation (> 20 dB) entre le trajet TX et RX est mis en oeuvre 1) par mise en forme des impulsions transmises pour tomber dans le spectre UWB non réglementé (3.1-7 GHz), et 2) par un filtrage espace-efficace du spectre de liaison descendante OOK dans un amplificateur à faible bruit RX. L’émetteur UWB 3.1-7 GHz peut utiliser soit OOK soit la modulation numérique binaire à déplacement de phase (BPSK). Le FDT proposé offre une double bande avec un taux de données de liaison montante de 500 Mbps TX et un taux de données de liaison descendante de 100 Mb/s RX, et il est entièrement en conformité avec les standards TSMC 0.18 um CMOS dans un volume total de 0,8 mm2. Ainsi, la mesure de consommation d’énergie totale en mode full duplex est de 10,4 mW (5 mW à 100 Mb/s pour RX, et de 5,4 mW à 500 Mb/s ou 10,8 PJ / bits pour TX). Notre cinquième contribution est une collaboration avec l’Université McGill dans laquelle nous concevons des antennes simples et à double polarisation pour les systèmes de détection du cancer du sein à l’aide d’hyperfréquences sans fil en utilisant un modèle multi-couche et inhomogène du sein humain. Les antennes fabriquées à partir de matériaux flexibles sont plus facilement adaptées à des applications portables. Les antennes flexibles miniaturisées monopôles et spirales sur un 50 um Kapton polyimide sont conçus, en utilisant high frequency structure simulator (HFSS), à être en contact avec des tissus biologiques du sein. Les antennes proposées sont conçues pour fonctionner dans une gamme de fréquences de 2 à 4 GHz. Les mesures montrent que les antennes flexibles ont une bonne adaptation d’impédance dans les différentes positions sur le sein. De Plus, deux antennes à bande ultralarge flexibles 4 × 4 (simple et à double polarisation), dans un format similaire à celui d’un soutien-gorge, ont été développés pour un système de détection du cancer du sein basé sur le radar.We are working on a fully wireless brain-machine-interface to provide a communication link between the brain and external devices, enabling recording and stimulating the brain for permanent usage. In this thesis we explore channel modeling, implanted and wearable antennas as suitable propagators for this application, system level design of an implantable UWB transceiver, and circuit level design and implementing it by TSMC 0.18 um CMOS process. Also, in a collaboration project with McGill University, we designed a flexible sixteen antenna array for microwave breast cancer detection. Our first contribution calculates channel characteristics of implant-to-air UWB wireless link, average specific absorption rate (ASAR), and FCC guidelines on transmitted UWB power spectral density. Knowledge of channel behavior is required to determine the maximum allowable power to 1) respect ANSI guidelines for avoiding tissue damage and 2) respect FCC guidelines on unlicensed transmissions. We utilize a realistic model of the biological channel to inform the design of antennas for the implanted transmitter and the external receiver. Antennas placement is examined under two scenarios having contrasting power constraints. Performance of the system within the biological tissues is examined via simulations and experiments. Our second contribution deals with designing single and dual-polarization antennas for wireless ultra-wideband neural recording systems using an inhomogeneous multi-layer model of the human head. Antennas made from flexible materials are more easily adapted to implantation; we investigate both flexible and rigid materials and examine performance trade-offs. The proposed antennas are designed to operate in a frequency range of 2–11 GHz (having S11 below -10 dB) covering both the 2.45 GHz (ISM) band and the 3.1–10.6 GHz UWB band. Measurements confirm simulation results showing flexible antennas have little performance degradation due to bending effects (in terms of impedance matching). Finally, a comparison is made of four implantable antennas covering the 2-11 GHz range: 1) rigid, single polarization, 2) rigid, dual polarization, 3) flexible, single polarization and 4) flexible, dual polarization. In all cases a rigid antenna is used outside the body, with an appropriate polarization. Several advantages were confirmed for dual polarization antennas: 1) smaller size, 2) lower sensitivity to angular misalignments, and 3) higher fidelity. Our third contribution provides system level design of wireless communication architecture for implanted systems that simultaneously stimulate neurons and record neural responses. This architecture supports large numbers of electrodes (> 500), providing 100 Mb/s for the downlink of stimulation signals, and Gb/s for the uplink neural recordings. We propose a transceiver architecture that shares one ultra-wideband antenna, a streamlined transceiver working at full-duplex on both bands, and a novel pulse shaper for the Gb/s uplink supporting several modulation formats. We present an ex-vivo experimental demonstration of the architecture using discrete components achieving Gb/s uplink rates. Good bit error rate performance over a biological channel at 0.5, 1, and 2 Gbps data rates for uplink telemetry (UWB) and 100 Mbps for downlink telemetry (2.45 GHz band) is achieved. Our fourth contribution presents circuit level design of the novel full-duplex transceiver (FDT) which is presented in our third contribution. This full-duplex transceiver supports high-density and multimodal neural interfacing applications (high-channel count stimulating and recording) with asymmetric data rates. The transmitter (TX) and receiver (RX) share a single antenna to reduce implant size. The TX uses impulse radio ultra-wide band (IR-UWB) based on an edge combining approach, and the RX uses a novel 2.4-GHz on-off keying (OOK) receiver. Proper isolation (> 20 dB) between the TX and RX path is implemented 1) by shaping the transmitted pulses to fall within the unregulated UWB spectrum (3.1-7 GHz), and 2) by spaceefficient filtering (avoiding a circulator or diplexer) of the downlink OOK spectrum in the RX low-noise amplifier. The UWB 3.1-7 GHz transmitter can use either OOK or binary phase shift keying (BPSK) modulation schemes. The proposed FDT provides dual band 500-Mbps TX uplink data rate and 100 Mbps RX downlink data rate, and it is fully integrated into standard TSMC 0.18 um CMOS within a total size of 0.8 mm2. The total measured power consumption is 10.4 mW in full duplex mode (5 mW at 100 Mbps for RX, and 5.4 mW at 500 Mbps or 10.8 pJ/bit for TX). Our fifth contribution is a collaboration project with McGill University which we design single and dual-polarization antennas for wireless ultra-wideband breast cancer detection systems using an inhomogeneous multi-layer model of the human breast. Antennas made from flexible materials are more easily adapted to wearable applications. Miniaturized flexible monopole and spiral antennas on a 50 um Kapton polyimide are designed, using a high frequency structure simulator (HFSS), to be in contact with biological breast tissues. The proposed antennas are designed to operate in a frequency range of 2–4 GHz (with reflection coefficient (S11) below -10 dB). Measurements show that the flexible antennas have good impedance matching while in different positions with different curvature around the breast. Furthermore, two flexible conformal 4×4 ultra-wideband antenna arrays (single and dual polarization), in a format similar to that of a bra, were developed for a radar-based breast cancer detection system

    Toward 3D UWB tomographie imaging system for breast tumor detection

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    A novel 3D tomographic algorithm for short range cylindrical geometries using UWB frequency range is presented. The algorithm has been applied to breast tumor detection, nevertheless, its non application-specific character permits the use in other applications. The detection capability of the tomographic algorithm is proved through numerical simulations and experimental measurements of canonical and more realistic bodyattached breast phantoms. For the acquisition of the experimental data, a virtual array-based cylindrical measurement setup has been built. At the current stage of development 3 degrees of freedom are available allowing the scanning of bodies with revolution symmetry.Peer ReviewedPostprint (published version

    Design and test of an imaging system for UWB breast cancer detection

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    Electromagnetic ultra-wideband (UWB) sensing and imaging provide perspectives for early-stage breast cancer detection. This paper deals with practical challenges of real measurements. We present an experimental setup for breast phantom trials based on M-sequence radar technology and short active dipole antennas. It combines short impulse responses, appropriate fidelity and very small antenna dimension and allows array construction with sufficient number of antennas around the breast. The basic approach and obtained imaging results are presented. Furthermore, in this extended paper version continuative development steps are described and measurement results reflecting specific performance aspects are discussed

    Differential ultra-wideband microwave imaging for medical applications

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    Elektromagnetische Ultrabreitband-Sensorik und -Bildgebung bieten vielversprechende Perspektiven für verschiedene biomedizinische Anwendungen, da diese Wellen biologisches Gewebe durchdringen können. Dabei stellt der Einsatz von leistungsarmen und nichtionisierenden Mikrowellen eine gesundheitlich unbedenkliche Untersuchungsmethode dar. Eine der Herausforderungen im Bereich der ultrabreitbandigen Mikrowellensensorik ist dabei die Extraktion der diagnostisch relevanten Informationen aus den Messdaten, da aufgrund der komplexen Wellenausbreitung im Gewebe meist rechenaufwändige Methoden notwendig sind. Dieses Problem wird wesentlich vereinfacht, wenn sich die Streueigenschaften des zu untersuchenden Objektes zeitlich ändern. Diese zeitliche Varianz der Streueigenschaften kann mit Hilfe einer Differenzmessung über ein bestimmtes Zeitintervall ausgenutzt werden. Im Rahmen dieser Arbeit wird der differentielle Ansatz mittels Ultrabreitband-Sensorik für zwei medizinische Anwendungsszenarien betrachtet. Die dabei genutzten Messsysteme basieren auf dem M-Sequenzverfahren, welches an der Technischen Universität Ilmenau entwickelt wurde. Die erste Anwendung bezieht sich auf das nicht-invasive Temperaturmonitoring mittels Ultrabreitband-Technologie während einer Hyperthermiebehandlung. Hyperthermie ist eine Wärmetherapie zur Unterstützung onkologischer Behandlungen (z. B. Chemo- oder Strahlentherapie). Während einer solchen Behandlung wird das Tumorgewebe um 4 °C bis 8 °C erhöht. Dabei ist es wichtig, dass die Temperatur die obere Grenze von 45 °C nicht überschreitet. In diesem Zusammenhang bietet das differentielle Ultrabreitband-Monitoring eine vielversprechende Technik zur kontinuierlichen und nicht-invasiven Messung der Temperatur im Körperinneren. Der Ansatz basiert auf den temperaturabhängigen dielektrischen Eigenschaften von biologischem Gewebe. Dabei werden elektromagnetische Wellen mit einer geringen Leistung in das Untersuchungsmedium eingebracht, die sich gemäß den dielektrischen Eigenschaften von Gewebe ausbreiten. Wird eine Zielregion (bspw. Tumor) erwärmt, so ändern sich dessen dielektrische Eigenschaften, was zu einem sich ändernden Streuverhalten der elektromagnetischen Welle führt. Diese Änderungen können mittels Ultrabreitband-Sensorik erfasst werden. Für die Evaluierung der gemessenen Änderungen im Radarsignal ist es notwendig, die temperaturabhängigen dielektrischen Eigenschaften von Gewebe im Mikrowellenfrequenzbereich zu kennen. Aufgrund der wenigen in der Literatur vorhandenen temperaturabhängigen dielektrischen Eigenschaften von Gewebe über einen breiten Mikrowellenfrequenzbereich werden in dieser Arbeit die dielektrischen Eigenschaften für Leber, Muskel, Fett und Blut im Temperaturbereich zwischen 30 °C und 50 °C von 500 MHz bis 7 GHz erfasst. Hierzu wird zunächst ein Messaufbau für die temperaturabhängige dielektrische Spektroskopie von Gewebe, Gewebeersatz und Flüssigkeiten vorgestellt und die wesentlichen Einflussfaktoren auf die Messungen analysiert. Die Messdaten werden mit Hilfe eines temperaturabhängigen Cole-Cole Models modelliert, um die dielektrischen Eigenschaften für beliebige Werte im untersuchten Temperatur- und Frequenzbereich berechnen zu können. In einem weiteren Experiment wird die nicht-invasive Erfassung von Temperaturänderungen mittels Ultrabreitband-Technologie in einem experimentellen Messaufbau nachgewiesen. Die Ergebnisse zeigen, dass eine Temperaturänderung von 1 °C zu Differenzsignalen führt, welche mit der genutzten Ultrabreitband-Sensorik (M-Sequenz) detektierbar sind. Die zweite Anwendung befasst sich mit der kontrastbasierten Mikrowellen-Brustkrebsbildgebung. Aufgrund des physiologisch gegebenen geringen dielektrischen Kontrastes zwischen Drüsen- und Tumorgewebe kann durch den Einsatz von Kontrastmitteln, im Speziellen magnetischen Nanopartikeln, die Zuverlässigkeit einer Diagnose verbessert werden. Der Ansatz beruht darauf, dass funktionalisierte magnetische Nanopartikel in der Lage sind, sich selektiv im Tumorgewebe zu akkumulieren, nachdem diese intravenös verabreicht wurden. Unter der Bedingung, dass sich eine ausreichende Menge der Nanopartikel im Tumor angesammelt hat, können diese durch ein äußeres polarisierendes Magnetfeld moduliert werden. Aufgrund der Modulation ändert sich das Streuverhalten der magnetischen Nanopartikel, was wiederum zu einem sich ändernden Rückstreuverhalten führt. Diese Änderungen können mittels leistungsarmen elektromagnetischen Wellen detektiert werden. In dieser Arbeit wird die Detektierbarkeit und Bildgebung von magnetischen Nanopartikeln mittels Ultrabreitband-Sensorik im Mikrowellenfrequenzbereich in Hinblick auf die Brustkrebsdetektion betrachtet. Dabei werden zunächst verschiedene Einflussfaktoren, wie die Abhängigkeit der Masse der magnetischen Nanopartikel, die Magnetfeldstärke des äußeren Magnetfeldes sowie die Viskosität des Umgebungsmediums, in das die Nanopartikel eingebettet sind, auf die Detektierbarkeit der magnetischen Nanopartikel untersucht. Die Ergebnisse zeigen eine lineare Abhängigkeit zwischen dem gemessenen Radarsignal und der Masse der magnetischen Nanopartikel sowie einen nichtlinearen Zusammenhang zwischen der Antwort der magnetischen Nanopartikel und der Feldstärke des äußeren Magnetfeldes. Darüber hinaus konnten die magnetischen Nanopartikel für alle untersuchten Viskositäten erfolgreich detektiert werden. Basierend auf diesen Voruntersuchungen wird ein realistischer Messaufbau für die kontrastbasierte Brustkrebsbildgebung vorgestellt. Die Evaluierung des Messaufbaus erfolgt mittels Phantommessungen, wobei die verwendeten Phantommaterialien die dielektrischen Eigenschaften von biologischem Gewebe imitieren, um eine möglichst hohe Aussagekraft der Ergebnisse hinsichtlich eines praktischen Messszenarios zu erhalten. Dabei wird die Detektierbarkeit und Bildgebung der magnetischen Nanopartikel in Abhängigkeit der Tumortiefe analysiert. Die Ergebnisse zeigen, dass die magnetischen Nanopartikel erfolgreich detektiert werden können. Dabei hängt im dreidimensionalen Bild die Intensität des Messsignals, hervorgerufen durch die magnetischen Nanopartikel, von deren Position ab. Die Ursachen hierfür sind die pfadabhängige Dämpfung der elektromagnetischen Wellen, die inhomogene Ausleuchtung des Mediums mittels Mikrowellen, da eine gleichmäßige Anordnung der Antennen aufgrund der Magnetpole des Elektromagneten nicht möglich ist, sowie das inhomogene polarisierende Magnetfeld innerhalb des Untersuchungsmediums. In Bezug auf den letzten Aspekt wird das Magnetfeld im Untersuchungsbereich ausgemessen und ein Ansatz präsentiert, mit dem die Inhomogenität des Magnetfeldes kompensiert werden kann. Weiterhin wurden die Störeinflüsse des polarisierenden Magnetfeldes auf das Messsystem untersucht. In diesem Zusammenhang werden zwei verschiedene Modulationsarten (eine Modulation mit den zwei Zuständen AN/AUS und eine periodische Modulation) des äußeren polarisierenden Magnetfeldes analysiert. Es wird gezeigt, dass mit beiden Modulationen die magnetischen Nanopartikel bildgebend dargestellt werden können. Abschließend werden die Ergebnisse in Hinblick auf die Störeinflüsse sowie ein praktisches Anwendungsszenario diskutiert.Electromagnetic ultra-wideband sensing and imaging provide promising perspectives in various biomedical applications as these waves can penetrate biological tissue. The use of low-power and nonionizing electromagnetic waves in the microwave frequency range offers an examination method that is harmless to health. One of the challenges in the field of ultra-wideband microwave sensor technology is the extraction of diagnostically relevant information from the measurement data, since the complex wave propagation in tissue usually requires computationally intensive methods. This problem is simplified when the scattering properties of the object under observation change with time. Such a time variance of the scattering properties can be exploited by means of a differential measurement over a certain time interval. In this work, a differential approach using ultra-wideband sensing is considered for two medical applications. The measurement systems used in this work are based on the M-sequence technology developed at the Technische Universität Ilmenau. The first application relates to noninvasive temperature monitoring using ultra-wideband technology during hyperthermia treatment. Hyperthermia is a thermal therapy to support oncological treatments (e.g. chemotherapy or radiotherapy). During such a treatment, the tumor tissue is heated by 4 °C to 8 °C, whereby it is important that the temperature does not exceed the upper limit of 45 °C. In this context, differential ultra-wideband monitoring offers a promising technique for continuous and noninvasive temperature monitoring inside the body. The approach is based on the temperature-dependent dielectric properties of biological tissue. In this method, low power electromagnetic waves are emitted into the medium under investigation. These waves propagate according to the dielectric properties of tissue. If a target region (e.g. tumor) is heated, its dielectric properties will change, which leads to a changing scattering behavior of the electromagnetic wave. These changes can be detected in the measured reflection signals using ultra-wideband microwave technology. To evaluate the measured changes in the radar signal, it is necessary to know the temperature-dependent dielectric properties of tissue in the microwave frequency range. Due to the lack of knowledge of temperature-dependent dielectric properties of tissues over a wide microwave frequency range, the dielectric properties for liver, muscle, fat and blood in the temperature range between 30 °C and 50 °C from 500 MHz to 7 GHz are acquired in this work. For this purpose, a measurement setup for the temperature-dependent dielectric spectroscopy of tissue, tissue substitutes and fluids is presented. Furthermore, the main influences on measuring the temperature-dependent dielectric properties are analyzed. The measured data are modeled using a temperature-dependent Cole-Cole model in order to calculate the dielectric properties for arbitrary values in the investigated temperature and frequency range. In a further experiment, the noninvasive detection of temperature changes using ultra-wideband microwave technology is demonstrated in an experimental measurement setup. The results show that a temperature change of 1 °C results in differential signals that are detectable by means of ultra-wideband pseudo-noise sensing (M-sequence). The second application is dealing with contrast enhanced microwave breast cancer imaging. Due to the physiologically given low dielectric contrast between glandular and tumor tissue, the use of contrast agents, specifically magnetic nanoparticles, can improve the diagnostic reliability. The approach is based on the assumption that functionalized magnetic nanoparticles are able to selectively accumulate in tumor tissue after intravenous administration. Provided that a sufficient amount of nanoparticles has accumulated in the tumor, they can be modulated by an external polarizing magnetic field. Due to the modulation, the scattering behavior of the magnetic nanoparticles changes, which results a changing backscattering behavior. This change can be detected using low-power electromagnetic waves. In this work, the detectability and imaging of magnetic nanoparticles by means of ultra-wideband pseudo-noise sensing in the microwave frequency range is considered with respect to breast cancer detection. First, various influencing factors on the detectability of the magnetic nanoparticles are investigated, such as the mass of the magnetic nanoparticles, the magnetic field strength of the external polarizing magnetic field and the viscosity of the surrounding medium in which the nanoparticles are embedded. The results reveal a linear dependence between the measured radar signal and the mass of the magnetic nanoparticles as well as a nonlinear relationship between the response signal of the magnetic nanoparticles and the magnetic field intensity of the external magnetic field. Furthermore, the magnetic nanoparticles can be successfully detected in all investigated viscosities of the surrounding medium. Based on these preliminary investigations, a realistic measurement setup for contrast enhanced microwave breast cancer imaging is presented. The evaluation of the measurement setup is performed by phantom measurements, where the used phantom materials mimic the dielectric properties of biological tissue to obtain significance of the results with respect to a practical measurement scenario. In this context, the detectability and imaging of the magnetic nanoparticles are analyzed depending on the tumor position and penetration depth, respectively. The results show that the magnetic nanoparticles can be successfully detected. However, the magnetic poles of the electromagnet limit the space for the transmitting and receiving antennas, resulting in an inhomogeneous microwave illumination of the medium under test, which leads to a location-dependent magnetic nanoparticle response. Furthermore, the intensity of the response signal caused by the magnetic nanoparticles in the three-dimensional image depends on their position due to the path-dependent attenuation and the inhomogeneous magnetic field within the investigated medium. Regarding the last point, the external polarizing magnetic field is measured in the investigation area and an approach to compensate for the inhomogeneity of the magnetic field is presented. In addition, the disturbing influences of the polarizing magnetic field on the measurement setup are analyzed. In this context, two different modulation types (a two-state and a periodic modulation) of the external polarizing magnetic field are investigated. It is shown that both modulations can be used to image the magnetic nanoparticles. Finally, the results are discussed with respect to the spurious effects as well as a practical application scenario

    UWB Pulse Radar for Human Imaging and Doppler Detection Applications

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    We were motivated to develop new technologies capable of identifying human life through walls. Our goal is to pinpoint multiple people at a time, which could pay dividends during military operations, disaster rescue efforts, or assisted-living. Such system requires the combination of two features in one platform: seeing-through wall localization and vital signs Doppler detection. Ultra-wideband (UWB) radar technology has been used due to its distinct advantages, such as ultra-low power, fine imaging resolution, good penetrating through wall characteristics, and high performance in noisy environment. Not only being widely used in imaging systems and ground penetrating detection, UWB radar also targets Doppler sensing, precise positioning and tracking, communications and measurement, and etc. A robust UWB pulse radar prototype has been developed and is presented here. The UWB pulse radar prototype integrates seeing-through imaging and Doppler detection features in one platform. Many challenges existing in implementing such a radar have been addressed extensively in this dissertation. Two Vivaldi antenna arrays have been designed and fabricated to cover 1.5-4.5 GHz and 1.5-10 GHz, respectively. A carrier-based pulse radar transceiver has been implemented to achieve a high dynamic range of 65dB. A 100 GSPS data acquisition module is prototyped using the off-the-shelf field-programmable gate array (FPGA) and analog-to-digital converter (ADC) based on a low cost solution: equivalent time sampling scheme. Ptolemy and transient simulation tools are used to accurately emulate the linear and nonlinear components in the comprehensive simulation platform, incorporated with electromagnetic theory to account for through wall effect and radar scattering. Imaging and Doppler detection examples have been given to demonstrate that such a “Biometrics-at-a-glance” would have a great impact on the security, rescuing, and biomedical applications in the future

    Application-Specific Broadband Antennas for Microwave Medical Imaging

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    The goal of this work is the introduction of efficient antenna structures on the basis of the requirement of different microwave imaging methods; i.e. quantitative and qualitative microwave imaging techniques. Several criteria are proposed for the evaluation of single element antenna structures for application in microwave imaging systems. The performance of the proposed antennas are evaluated in simulation and measurement scenarios

    Evaluating a breast tumor monitoring vest with flexible UWB antennas and realistic phantoms:a proof-of-concept study

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    Abstract. The introduction provides an overview of the global significance of breast cancer as a health concern and the limitations of existing breast cancer screening methods. It introduces the concept of microwave-based breast cancer monitoring and highlights the promising findings from a previous research paper. The objective of the master thesis is presented, which is to develop and evaluate a self-monitoring vest equipped with UWB antennas and channel analysis to overcome the limitations of current screening methods and enable regular breast cancer monitoring from home. The "Background and Literature Review," provides a comprehensive overview of the relevant topics related to microwave techniques for breast cancer detection. It starts by discussing the anatomy of the female breast, highlighting the importance of understanding its structure for effective tumor detection. The section then delves into the microwave properties of the human breast, elucidating the interactions between microwaves and breast tissue. The basic principle of microwave channel analysis is explained, emphasizing its significance in detecting breast tumors. Furthermore, the advantages of microwave-based tumor detection methods are explored, showcasing their potential for improved breast cancer screening. Various microwave techniques used in breast cancer detection, including microwave tomography and radar-based UWB microwave imaging, are discussed, along with different self-monitoring vests integrated with UWB antennas. This section serves as a foundation for the subsequent chapters of the thesis, providing a comprehensive background and literature review to support the research and development of the practical self-monitoring vest for early detection of small-sized breast tumors. The "Preparation of Tissue Phantoms" section in the master’s thesis explores the comprehensive methodology for creating tissue phantoms that replicate the dielectric properties of various human tissues. While the section primarily focuses on fat tissue, it also acknowledges the existence of other phantom types. The outlined approach involves careful ingredient selection, formulation development, fabrication techniques, and stability evaluation for the creation of skin, muscle, fat, tumor, and gland tissue phantoms. By following these procedures, researchers can successfully produce tissue phantoms that closely mimic the properties of real human tissues. These phantoms serve as essential tools for investigating microwave-based applications in medical diagnostics and provide a reliable and versatile platform for further research in the field. The third section discusses the assembly of heterogeneous breast phantoms used for evaluating the performance of the tumor detection vest. The phantoms consisted of outer and inner molds, with the outer molds resembling the shape of a prone human breast. Two breast density types, representing very dense and less dense breasts, were used. For the dense breast phantoms, liquid fat material was solidified in the outer molds, and a glandular liquid was poured into the inner mold, with tumors inserted and covered with additional glandular liquid. For the less dense breast phantoms, fat liquid was solidified in the outer molds, and cylindrical glandular molds were inserted. A skin layer and muscle layer were added to complete the assembly, accurately simulating the composition and structure of a breast. This realistic breast phantom assembly allowed for accurate measurements and evaluation of the vest’s performance under different breast density conditions, contributing to breast imaging research and development. The "Monitoring Vest" section discusses the antennas used in the tumor detection vest and the design of two different vest versions. Antenna1 is a UWB monopole antenna with a flexible laminate substrate, while Antenna2 is a textile-based version of Antenna1. Antenna3 has a Kapton-based substrate and larger dimensions. The combination of these antennas ensures accurate tumor detection in various breast conditions. The section also highlights the measurement and comparison of the S11 parameter for the PCB antenna in free space and when placed on the skin, emphasizing the impact of the skin on antenna performance. The section concludes by describing the design of the vests, including the arrangement of pockets and the use of RF cables for connection. The careful design and implementation of the vests and antenna placement ensure accurate measurements and reliable performance evaluation. The results section of the study shows that the presence of tumors in breast tissue leads to a noticeable decrease in channel attenuation. The higher dielectric properties of tumors cause additional reflections and diffraction, affecting signal propagation within the breast. These changes in channel characteristics are influenced by factors such as tumor size, breast density, and antenna configuration. The study demonstrates the detectability of tumors and provides valuable insights for developing effective tumor detection systems in different breast tissue scenarios. In this master thesis, a prototype of a breast tumor monitoring vest utilizing UWB flexible antennas was developed and evaluated. The research demonstrated the effectiveness of the vest in detecting breast tumors, even as small as 1cm, by leveraging the distinct characteristics of radio channels among multiple on-body antennas embedded in the vest. Higher frequencies in the 7–8 GHz range showed improved resolution and contrast in relative permittivity, enhancing the accuracy of tumor detection. The development of tissue phantoms played a crucial role, enabling reliable experiments to mimic human tissues. Integration of advanced AI algorithms and 6G technology holds promise for enhancing diagnostic capabilities and revolutionizing healthcare. Overall, the breast tumor monitoring vest shows potential for widespread implementation in breast health checks, home monitoring, and wireless healthcare systems
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