A Planar Interdigital Sensor for Bio-impedance Measurement: Theoretical analysis, Optimization and Simulation

This paper proposes the design of a biosensor to characterize the dielectric and conductive properties of biological materials (for example blood or water) by impedance spectroscopy. Particularly, its design optimized the geometric structure interdigitated electrodes. This optimization allows extending the frequency range of measurement by reducing the polarization effect. Polarization effect is manifested by an interface capability (or double layer) from interaction between ions and molecules in the boundary between the surface of the electrolyte and the electrodes, it increases the measurement error at low frequencies. This paper recommends also a novel method to determine the parameters (relative permittivity, thickness and capacitance per unit area) of the double layer (DL) at the contact surface of the electrode with the solution. CoventorWare software was utilized to modelize of interdigital sensor structure in three dimensions (3D) to verify the analytical results and evaluate the influence of geometrical parameters and the dielectric properties of the medium on bioelectrical impedance. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3582

A Planar Interdigital Sensor for Bio-impedance Measurement: Theoretical analysis, Optimization and Simulation

This paper proposes the design of a biosensor to characterize the dielectric and conductive properties of biological materials (for example blood or water) by impedance spectroscopy. Particularly, its design optimized the geometric structure interdigitated electrodes. This optimization allows extending the frequency range of measurement by reducing the polarization effect. Polarization effect is manifested by an interface capability (or double layer) from interaction between ions and molecules in the boundary between the surface of the electrolyte and the electrodes, it increases the measurement error at low frequencies. This paper recommends also a novel method to determine the parameters (relative permittivity, thickness and capacitance per unit area) of the double layer (DL) at the contact surface of the electrode with the solution. CoventorWare software was utilized to modelize of interdigital sensor structure in three dimensions (3D) to verify the analytical results and evaluate the influence of geometrical parameters and the dielectric properties of the medium on bioelectrical impedance. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3443

Modélisation de systèmes ultrasonores avec VHDL-AMS (Application à la mesure du paramètre de non linéarité B/A)

Ce travail aborde la modélisation des systèmes ultrasonores avec VHDL-AMS. Le but recherché est la prédiction du comportement d'une cellule de mesure dédiée à la mesure des non linéarités ultrasonores. Afin de prévoir dans un futur proche la miniaturisation et la conception d'un système de mesure dont les performances seront estimables grâce à nos modèles, nous procédons par une décomposition du système de mesure en associant à chacun des éléments un modèle comportemental développé en langage VHDL-AMS. L'originalité de nos travaux repose sur la prise en compte du paramètre de non linéarité B/A dans la modélisation du milieu de propagation. Les résultats de simulation sont rigoureusement comparés avec les outils tels que Matlab ou PSPICE et ainsi que les mesures obtenues in-vitro. Ce travail se décompose en 4 parties : L'état de l'art de la modélisation des systèmes ultrasonores ; L'analyse théorique de la propagation non linéaire et les méthodes de mesure du paramètre B/A ; La modélisation des transducteurs piézocéramiques et du milieu de propagation non linéaire avec VHDL-AMS ; La modélisation et la conception d'une cellule de mesure des non linéarités ultrasonores en pulse-écho et transmission. Les résultats obtenus prédisent à priori qu'un milieu peut être caractérisé en fonction de la mesure du paramètre B/A estimé pour certains milieux liquides et biologiques. Les perspectives ouvertes par ce travail ont été soulignées par des membres de la communauté scientifiques à différents congrès internationaux.This thesis abords ultrasound modelling systems with VHDL-AMS. Goal is prediction of a measurement cell behaviour dedicated to ultrasound non linearity measurements. To preview in a near future miniaturisation and conception of a measurement system which performances could be estimated with ours models, we proceed by a decomposition of the measurement system with associating to each elements a behavioural model developed in VHDL-AMS language. Originality of ours works is the integration of the non linearity parameter B/A in the propagation medium modelling. Simulation results are rigorously compared to implantation in Matlab and PSPICE software and in vitro measurement. This work is divided in 4 parts : State of the art of the ultrasound modelling systems ; Theoretical analysis of the non linear propagation and measurement methods of the parameter B/A ; Piezoceramic transducers and non linear medium modelling with VHDL-AMS ; Modelling and conception of a non linearity measurement cell in pulse-echo and transmission mode. Results obtained show that a medium could be characterized as function to the B/A parameter estimated with different biological and liquid mediums. Perspectives open by this work has been highlighted by scientific community members at different international congress.NANCY1-SCD Sciences & Techniques (545782101) / SudocSudocFranceF

Théorie géométrique de la diffraction appliquée à la caractérisation expérimentale des propriétés acoustiques et dimensionnelles de la diaphyse osseuse

NANCY1-SCD Sciences & Techniques (545782101) / SudocSudocFranceF

Rays theory for experimental characterisation of acoustical and dimensional properties of bone diaphysis

Ultrasound, bone, diaphysis,International audienceThe aim of this study is to establish an instrumental approach allowing dimensional and acoustical characterization of the cortical thickness and of the medullar marrow constituting the bone diaphysis. This one is modeled by a hollow cylinder. The solution of the direct problem, which is required before the evaluation of the searched parameters, is done using the Theory of Rays. The parameters are evaluated from the delay phase of reflected and transmitted waves in the tube. The precision of the theoretical estimation of arrival times of echoes is then experimentally verified. The solution of the inverse problem is next approached and validated on test objects made of Plexiglas and Duraluminium as well as in vitro on bovine samples. The whole results are very satisfactory. The acoustical velocities reported are in keeping with reference data and the dimensional parameters evaluated follow the internal and external outlines of the bone diaphysis in a satisfactory way

Acoustical characterization of bone using a cylindrical model and time of flight method: edge reconstruction and ultrasound velocity determination in cortical bone and in medullar marrow

International audienceOur objective is to evaluate the external and internal dimensions of bone diaphysis and the speed of sound in cortical bone and in medullar marrow. The diaphysis is modelled by a cylindrical hollow tube. The theory of rays is used and an approximation allows us to break free from the data gained by ultrasonic field amplitude. Then, acoustical and dimensional parameters are only related to the time of flight of reflected and transmitted acoustic echoes in the tube. From the arrival time of particular echoes, the inverse problem resolution then allows us to experimentally determine the sought parameters. This method is validated in vitro on a bovine femur and gives satisfactory results