UWB Characteristics of RF Propagation for Body Mounted and Implanted Sensors

Body Area Network (BAN) technology is related to many applications inside, on and around the human body. The basic configuration of a BAN is a set of sensors, which are wearable or are placed inside the human body, transmitting signals to a terminal situated in a doctor’s office, in order to assess or monitor some aspect of a patient’s physical condition. Additionally, in many BAN applications the information about the sensor location is very important, since without knowing a sensor’s location, the transmitted data may be of limited value. As an example, Wireless Video Capsule Endoscopy (VCE) can benefit greatly from the addition of location information. The capsule transmits an RF signal from inside the human body to another sensor on the body surface or external. From the image data provided by the capsule, taken together with the location information, the doctor can locate the infection or lesion and initiate appropriate medical care. In this way, the treatment can be more effective and accurate. In this thesis we investigate the characteristics of Ultra-Wide Band (UWB) RF propagation for BAN devices placed around and inside the human body. We have made measurements around the human body and around a water-filled phantom using an E8363B Vector Network Analyzer (VNA), specifically measuring the S21 signal, which gives the transfer function. Based on these measurement results, we discuss the channel propagation for cases where the transmitter and the receiver are on the surface of the body and analyze the UWB propagation characteristics for RF localization. Because it is impractical or even impossible to make measurements inside the human body, we chose to apply the measurements using a simulation model of homogenous tissue, which serves as an approximation of the signal propagation environment inside the body. First, by comparing the multipath situation in free space and within a model of homogenous tissue, we are able to analyze the multipath effects inside human body. Then, because of the different characteristics of RF propagation in different bandwidths, we have made measurements at UWB (3GHz to 10GHz), and narrowband (402MHz) frequencies

Increasing the robustness of active upper limb prostheses

This thesis is based on my work done at the Institute for Neurorehabilitation Systems at the University Medical Center Goettingen. My work has been partially founded by German Ministry for Education and Research (BMBF) via the Bernstein Focus Neurotechnology (BFNT) Göttingen under grant number 1GQ0810 The local ethics committee approved all studies involving human subjects, and all subjects signed informed consents prior to their participation in the studies. The entire thesis has been originally written by me. Part of the materials used in this thesis have also been published in journals or conferences, where I am the first or corresponding author. All rights for re-use of previously published material were obtained. Reused figures and tables of IEEE publications are marked with © [Year] IEEE. Hereby I declare that I have written this thesis independently and with no other aids and sources than quoted

Bounds on RF cooperative localization for video capsule endoscopy

Wireless video capsule endoscopy has been in use for over a decade and it uses radio frequency (RF) signals to transmit approximately fifty five thousands clear pictures of inside the GI tract to the body-mounted sensor array. However, physician has no clue on the exact location of the capsule inside the GI tract to associate it with the pictures showing abnormalities such as bleeding or tumors. It is desirable to use the same RF signal for localization of the VCE as it passes through the human GI tract. In this thesis, we address the accuracy limits of RF localization techniques for VCE localization applications. We present an assessment of the accuracy of cooperative localization of VCE using radio frequency (RF) signals with particular emphasis on localization inside the small intestine. We derive the Cramer-Rao Lower Bound (CRLB) for cooperative location estimators using the received signal strength(RSS) or the time of arrival (TOA) of the RF signal. Our derivations are based on a three-dimension human body model, an existing model for RSS propagation from implant organs to body surface and a TOA ranging error model for the effects of non-homogenity of the human body on TOA of the RF signals. Using models for RSS and TOA errors, we first calculate the 3D CRLB bounds for cooperative localization of the VCE in three major digestive organs in the path of GI tract: the stomach, the small intestine and the large intestine. Then we analyze the performance of localization techniques on a typical path inside the small intestine. Our analysis includes the effects of number of external sensors, the external sensor array topology, number of VCE in cooperation and the random variations in transmit power from the capsule

Brain Tumour Classification Using Deep Features from Structural MRI

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Antenna Systems

This book offers an up-to-date and comprehensive review of modern antenna systems and their applications in the fields of contemporary wireless systems. It constitutes a useful resource of new material, including stochastic versus ray tracing wireless channel modeling for 5G and V2X applications and implantable devices. Chapters discuss modern metalens antennas in microwaves, terahertz, and optical domain. Moreover, the book presents new material on antenna arrays for 5G massive MIMO beamforming. Finally, it discusses new methods, devices, and technologies to enhance the performance of antenna systems

Estimation and control of the pump pressure rise and flow from intrinsic parameters for a magnetically-levitated axial blood pump

An increase in the number of cardiac patients and a decrease in number of heart donors has triggered the development of artificial heart pump to support the proper functioning of the heart. There is also an increase in demand for smaller sized pumps with long term application. All these factors have stimulated the use of a magnetically-levitated rotary blood pump as Left Ventricular Assistant Devices. The demand of volume and pressure of blood varies from person to person. Moreover, the prevention of cannular ventricle collapse at suction, dependence of pump performance on its inlet, and outlet conditions has necessitated control of the pump. Also, the available invasive pressure and flow transducers limit the use, due to their low reliability, periodic calibration, and assembling problem. In this work, three independent and quantitative non-invasive measurement methods for the estimation of pump parameters from intrinsic parameters were developed, substantiated, and compared. The first method used DC motor current and the motor speed as the inputs to the system. In this method, behavior of brushless DC motor was studied using its working model. Pump speed and bearing current were the inputs for the second estimation technique. In this method, pump performance and impeller behavior were continuously monitored in three axes (X,Y, ). The third method is conceptualized on the output of the Hall Effect sensors, which were used for sensing the position of impeller, and the pump speed. The behavior of the sensor output with the impeller position in four axes (X,Y,Z, ) was developed using a real impeller in model housing. The data were analyzed in Microsoft Excel 2007 and MATLAB using least square estimation techniques and Fourier series expansion. An algorithm for each technique was developed. In addition, the propagation of errors and uncertainties at each step of estimation method were accounted and calculated, with the results for each method compared

Development of multi-material phantoms and implanted monopole antennas for bone fracture monitoring

This thesis presents a novel method for monitoring the healing of severe bone fractures. This would be particularly useful during the first two to four weeks after trauma where x-ray and computerised tomography scanning cannot provide an accurate indication regarding the healing status of the fractured bone. The technique involves measuring the radiofrequency transmission from one bone-implanted monopole to another, each one located on either side of the bone fracture. Throughout this thesis, it is envisaged that the monopoles will also act as the screws of an external fixation implanted into patients for the stabilization and alignment of the bone fragments. To replicate a simplified version of a human limb, several multi-material semi-solid phantoms were developed to represent bone marrow, bone cortical, blood and muscle. Medical literature indicates that the amount of blood found at the initial stage of a bone fracture decreases as bone regeneration takes place towards the healed state. The rate of change of the 21 of the implanted monopoles over time was shown to provide a tool that allowed the estimation of the amount of blood (hematoma) inside any bone fracture. In this thesis it has been shown that as the effective dielectric properties of the investigated fractured area shifted from the dielectric properties of blood towards the properties of bone, the 21 of the monopoles increased, thus, this technique can be used to indicate bone healing. The simulated results were validated in measurements using several multi-material phantoms and a real lamb joint. Finally, an analytical model on the approximation of the 21 of the monopoles in the near field inside the multi-material phantoms was developed. The results showed good agreement over the frequency spectrum of 1 to 4GHz and reasonable agreement over the parametric investigation of separation distance between them for the range of 1 to 7cm. This will potentially allow the application of the proposed technique for special types of fractures where the screws of the external fixation are separated by different distances

Modern Telemetry

Telemetry is based on knowledge of various disciplines like Electronics, Measurement, Control and Communication along with their combination. This fact leads to a need of studying and understanding of these principles before the usage of Telemetry on selected problem solving. Spending time is however many times returned in form of obtained data or knowledge which telemetry system can provide. Usage of telemetry can be found in many areas from military through biomedical to real medical applications. Modern way to create a wireless sensors remotely connected to central system with artificial intelligence provide many new, sometimes unusual ways to get a knowledge about remote objects behaviour. This book is intended to present some new up to date accesses to telemetry problems solving by use of new sensors conceptions, new wireless transfer or communication techniques, data collection or processing techniques as well as several real use case scenarios describing model examples. Most of book chapters deals with many real cases of telemetry issues which can be used as a cookbooks for your own telemetry related problems