Magnetic Transceiver Beamforming for A 2 × 2 Magnetic Resonance Charging System
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The formulated problem is nonconvex and we propose an efficient iterative solution by solving a series of geometric programs that approximate the original problem. Both numerical results and simulation results in COMSOL model are provided to demonstrate the effectiveness of the proposed biomedical wearable system and optimization algorithm.
Transmission Line Model Of An Implemented Insulated Cable For Magnetic Resonance Imaging Radiofrequency Hazard Evaluation
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The equivalence between the models is shown through a finite difference model and a new analytical formula for the transfer function as a function of transmission line parameters. First, the possibility of modeling an insulated cable with a transmission line model was analyzed through full-wave numerical simulations. The assumption of a transmission line model underlying the transfer function model was shown to be right for a simple cable embedded in tissue imitating gel and the transmission line parameters extracted from this analysis were consistent with analytical formulas derived from the laws of physics. The transmission line model predictions were first compared to experimental and simulated data of the cable transfer function and then, to experimental and simulated data of the resonant behavior as a function of length of cables with different termination conditions. The measured and simulated transfer functions fit perfectly a transmission line model with an analytical expression of the propagating constant. The transmission line model extracted from the transfer function allows to predict the resonant behavior of two cables with different termination conditions
Magnetoresistive Biosensors for On-Chip Detection and Localisation of Paramagnetic Particles
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A new calibration and localisation algorithm has been coded and implemented. In order to generate the required homogenous magnetic field, a custom 3D printed Hallbach cylinder has been simulated and characterised. The system includes sensory and electronic boards to collect the data and to transfer them to a computing server. The experimental results are displayed in a visual interface. Ferrofluid is used to model and simulate the magnetic field change of the cell. This paper demonstrates a 4×4 sensors array and provides a step towards the miniaturised on-chip magnetoresistive based cell detection and localisation for portable diagnostics applications.
Characterisation of the Dielectric Properties of the Bladder over the Microwave Range
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A number of such technologies have been proposed to target the diagnosis or treatment of bladder conditions, including urinary incontinence and bladder cancer. However, available dielectric data for the bladder is extremely limited in scope and has not been updated in line with modern knowledge, including best practices in measurement procedures to reduce the impact of confounders, along with improved reporting of experimental metadata. For these reasons, in this work we present a study of dielectric measurements on the bladder of freshly excised bovine and porcine tissues over the microwave frequency range. We examine the properties of the inside and outside of the bladder wall, and carefully control and record confounders during the measurements. The obtained data is analysed in terms of confounders (temperature, time from excision, inter-species differences), and compared to data from the literature. The resulting dataset, composed of 52 measurements from 10 animals, provides a thorough and quantitative understanding of the dielectric properties of the bladder. The results of this study will benefit the development of related electromagnetic medical technologies, and thereby positively impact on patient care over the long-term.
A Miniaturized Four-Element MIMO Antenna with EBG for Implantable Medical Devices
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A cross-shaped slot etched in the radiator, a branch extending on the conductor ground, and a pair of electromagnetic band gaps (EBGs) are integrated to achieve high isolation. The proposed MIMO antenna has the compact dimensions of 18.5 mm × 18.5 mm × 1.27 mm. The simula-tion in the three-layer phantom indicates that the impedance matching is good with a bandwidth of 18.64% (2.14-2.58 GHz) and a maximum gain of -15.18 dBi and the mutual coupling is reduced to less than -15.99 dB at the ISM band. An ex-vivo test was implemented in a fresh pork slab and the measurement results are well matched with the simulation ones. Health safety considerations and link budget are discussed to validate the antenna’s availability in biomedical telemetry, and the envelope correlation coefficient is computed, illustrating the high independence between antenna elements.
Magnetic and Thermal Characterization of Core-Shell Fe-oxide@SiO2Nanoparticles for Hyperthermia Applications
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Their size remains therefore as small as possible, while still displaying significant hysteresis losses in dynamic conditions (electromagnetic fields up to 48 kA/m at 100 kHz). Static loops measured by vibrating sample magnetometry and dynamic loops measured by a custom B-H tracer are used to characterize the particles magnetic properties, as well as a custom-built, fully modelled, hyperthermia setup. The specific absorption rate is obtained either from static and dynamic loops areas, and from direct hyperthermia measurements. Dynamic loops are shown to be a good estimator of specific absorption rate values.
