Dissertations / Theses on the topic 'Magnetostrictive transducers'

Thesis (M.S.)--University of Missouri-Columbia, 2008.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 12, 2008) Includes bibliographical references.

Magnetostrictive transducers have been used for many years by dentists for the removal of deposits on teeth that contribute to tooth decay. A study of current commercial magnetostrictive scalers has been undertaken so that potentially beneficial modifications to the present designs could be identified and investigated. This has resulted in suggestions for upgrades to the drive coil design and changes to the frequency of the applied dynamic magnetic field (which produces magnetostriction) that could improve system performance. In addition, a 'capacitance compensation system' has been produced and tested that significantly reduces the power requirements for current and future dental scalers by compensating for dynamic losses in a resonant transducer. Magnetostrictive materials are identified as replacement for those currently used in dental scalers. It is demonstrated that although they possess some of the qualities that could offer advantages for new types of dental scalers, they are unable to produce satisfactory results when compared to extant nickel-based systems if based on current device geometries. Finite element modelling has been used to investigate the mode-shapes associated with resonant magnetostrictive dental scaler components. The modelling indicates that flexural modes can be generated and the resultant flexing of 'tips' are equivalent to those measured in real devices. In addition, it is shown that coupled longitudinal-flexural resonant modes must be stimulated to produce the required tip vibrations for dental scaling. Suggestions are also made for future work that includes the development of more advanced finite element models, improved dental scaler designs and new transducer measurement techniques.

No presente trabalho, foi construído um transdutor para medir as variações da indução magnética (B) e magnetostricção (?) de materiais ferromagnéticos macios em função de campo magnético aplicado (H) (voltagem V) e tensões mecânicas (?). O transdutor possui duas bobinas de excitação ligadas a uma fonte de corrente/voltagem (para aplicar o campo magnético no elemento magnetostrictivo) e um núcleo magnético, para concentrar o fluxo magnético no material ferromagnético. A magnetostricção é medida por extensômetria, a tensão mecânica é aplicada por uma máquina de ensaios universal (EMIC), a indução magnética é medida utilizando uma bobina de captura conectada a um fluxímetro e a aquisição dos dados foi realizada por um programa em Labview. O sistema mede curvas de M vs V e ? vs V para ? constante e também M vs ? e ? vs ? para V constante. A partir dessas curvas, é possível adquirir a sensibilidade do material e analisar a sua viabilidade em aplicações como sensores e atuadores. Utilizando este transdutor, foi possível caracterizar uma liga de FeAlB e comparar com uma amostra de GALFENOL, que é o material mais usado desta classe. As ligas apresentam sensibilidades (acima de 10 MPa) da ordem de 0,020 T/MPa para o GALFENOL e 0,012 T/MPa para a liga de FeAlB. Considerando que a liga de FeAlB não apresenta a melhor composição química, há muitas coisas para estudar ainda, como diferentes composições químicas e o processamento adequado para obter a textura desejada.
In the present research, a transducer was built to measure the changes of magnetic induction (B) and magnetostriction (?) for soft ferromagnetic materials in function of applied magnetic field (H) (voltage V) and mechanical stress (?).The transducer comprises two excitation coils connected at a current/voltage supply (to apply the magnetic field in the magnetostrictive element) and a magnetic core, to concentrate the magnetic flux in the ferromagnetic material. The magnetostriction is measured by strain gauges, the mechanical stress is applied by a material test system (EMIC), the magnetic induction is measured using a pick-up coil connected to a fluxmeter and the acquisition of the data was measured by a Labview software. These systems measure the curve B vs. V and ? vs. V for constant ? and B vs. ? e ? vs. ? for constant V. From this curves, it is possible to acquire the material´s sensibility and analyse the feasibility of then in application like sensor and actuators. Using this transducer, it was possible to characterize a FeAlB alloy and to compare it with a GALFENOL sample, which is the most used material of this class. The alloys show sensibility (up to 10 MPa) about 0,020 T/MPa to the GALFENOL and 0,012 T/MPa to FeAlB alloy. If we consider that the FeAlB alloy does not have the best chemical composition to reach the higher magnetostriction, there is a lot o thing to study, like different composition and the appropriate processing to obtain the desired texture.

Дисертація на здобуття наукового ступеня кандидата технічних наук (доктора філософії) за спеціальністю 05.11.13 – прилади і методи контролю та визначення складу речовин. – Східноукраїнський національний університет ім. В. Даля, Сєвєродонецьк. Захист відбудеться на засіданні спеціалізованої вченої ради Д 64.050.09 у Національному технічному університеті "Харківський політехнічний інститут", Харків, 2018. Дисертація присвячена вирішенню важливої науково-прикладної задачі – розробці магнітострикційного рівнеміра рідинних середовищ, який дозволяє підвищити ефективність використання ємностей за рахунок зменшення зони нечутливості, розширення діапазону та зменшення похибок вимірювання. На основі теорії реологічних перетворень досліджені електромеханічні процеси в магнітострикційному перетворювачі. Перетворювачі описуються нелінійними диференціальними рівняннями, що дало можливість вивчити вплив нелінійності на метрологічні характеристики рівнеміра та розробити заходи щодо їх покращення. Отримано математичні моделі запропонованого рівнеміра в аналітичній формі. Виконано дослідження похибок вимірювання методом інтегрального функціоналу. Запропоновано структурну схему магнітострикційного рівнеміра з багатократним відбиттям ультразвукового торсійного імпульсу та розроблені алгоритми обробки вимірювальної інформації і програмне забезпечення для мікропроцесора.
Candidate of Engineering Science (PhD) thesis in speciality 05.11.13 "Devices and Methods of Control and Determination of Substance Composition" – Volodymyr Dahl East Ukrainian National University, Severodonetsk, 2017. Defence will be held at the meeting of the Specialized Scientific Council D 64.050.09 at the National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2018. The thesis is devoted to solving an important scientific and applied problem – development of the magnetostrictive level sensor of liquid media, which allows to increase efficiency of using capacities by reducing the dead zone, expanding the range and reducing the measurement errors. On the basis of the rheological transformations theory, the electromechanical processes in the magnetostrictive transducer have been researched. Transducers are described by nonlinear differential equations, allowing to study the influence of nonlinearity on the metrological characteristics of the level sensor and to develop measures for their improvement. The mathematical models of the proposed level sensor have been obtained in the analytical form. The study of measurement errors has been performed by the integral-type functional method. The structural scheme of the magnetostrictive level sensor with multiple reflection of the ultrasonic torsional pulse has been proposed, and the algorithms for the measuring information processing and the software for the microprocessor have been developed.

Дисертація на здобуття наукового ступеня кандидата технічних наук (доктора філософії) за спеціальністю 05.11.13 – прилади і методи контролю та визначення складу речовин. – Східноукраїнський національний університет ім. В. Даля, Сєвєродонецьк. Захист відбудеться на засіданні спеціалізованої вченої ради Д 64.050.09 у Національному технічному університеті "Харківський політехнічний інститут", Харків, 2018. Дисертація присвячена вирішенню важливої науково-прикладної задачі – розробці магнітострикційного рівнеміра рідинних середовищ, який дозволяє підвищити ефективність використання ємностей за рахунок зменшення зони нечутливості, розширення діапазону та зменшення похибок вимірювання. На основі теорії реологічних перетворень досліджені електромеханічні процеси в магнітострикційному перетворювачі. Перетворювачі описуються нелінійними диференціальними рівняннями, що дало можливість вивчити вплив нелінійності на метрологічні характеристики рівнеміра та розробити заходи щодо їх покращення. Отримано математичні моделі запропонованого рівнеміра в аналітичній формі. Виконано дослідження похибок вимірювання методом інтегрального функціоналу. Запропоновано структурну схему магнітострикційного рівнеміра з багатократним відбиттям ультразвукового торсійного імпульсу та розроблені алгоритми обробки вимірювальної інформації і програмне забезпечення для мікропроцесора.
Candidate of Engineering Science (PhD) thesis in speciality 05.11.13 "Devices and Methods of Control and Determination of Substance Composition" – Volodymyr Dahl East Ukrainian National University, Severodonetsk, 2017. Defence will be held at the meeting of the Specialized Scientific Council D 64.050.09 at the National Technical University "Kharkiv Polytechnic Institute", Kharkiv, 2018. The thesis is devoted to solving an important scientific and applied problem – development of the magnetostrictive level sensor of liquid media, which allows to increase efficiency of using capacities by reducing the dead zone, expanding the range and reducing the measurement errors. On the basis of the rheological transformations theory, the electromechanical processes in the magnetostrictive transducer have been researched. Transducers are described by nonlinear differential equations, allowing to study the influence of nonlinearity on the metrological characteristics of the level sensor and to develop measures for their improvement. The mathematical models of the proposed level sensor have been obtained in the analytical form. The study of measurement errors has been performed by the integral-type functional method. The structural scheme of the magnetostrictive level sensor with multiple reflection of the ultrasonic torsional pulse has been proposed, and the algorithms for the measuring information processing and the software for the microprocessor have been developed.

Actuellement, le marché des implants offre milliers de dispositifs différents pour diagnostiquer, traiter et suivre le patient. Dans la dernière décennie, d'importants travaux de recherche ont permis de rendre les dispositifs implantés plus durables et moins invasifs. La source d'énergie la plus utilisée reste néanmoins la pile électrochimique à usage unique. Pour un implant à long terme, il est nécessaire de remplacer la pile déchargée, ce qui nécessite une intervention chirurgicale coûteuse et invasive. Pour résoudre ces problèmes, deux approches ont été récemment proposées, la première consiste à utiliser l'énergie biomécanique du corps, et la deuxième consiste à transmettre de l'énergie depuis l'extérieur du corps humain. Dans le premier cas, par exemple, il est possible d'alimenter la nouvelle génération de pacemaker avec un MEMS piézoélectrique en utilisant l’énergie mécanique fournie par les battements cardiaques. Dans le deuxième cas, la télé-alimentation par induction entre deux bobines (l'une dans l'implant, l'autre à l'extérieur du corps) est une technologie de plus en plus répandue dans le secteur biomédical. Une différence importante entre ces deux techniques concerne les niveaux de puissance atteints : quelques µW pour la récupération d'énergie, et de quelques mW au W pour la télé-alimentation. Durant cette thèse, une nouvelle technologie de télé-alimentation a été développée. Le système considéré est constitué de deux blocs principaux, l'émetteur (situé à l’extérieur du corps) et le récepteur (situé dans l'implant). L'émetteur est constitué d’une bobine, sur laquelle il y a peu de contraintes en termes de taille et de position sur le corps. Le récepteur est un transducteur magnétoélectrique (ME). L’utilisation de ce système ME est notamment motivée par la possibilité de s’affranchir -au moins en partie- des contraintes d'alignement du système classique de bobine-bobine, alignement difficile à assurer dans le cas des dispositifs implantables. Le transducteur ME considéré est un composite constitué de matériaux piézoélectriques et magnétostrictifs. L’élément magnétostrictif a la propriété de se déformer mécaniquement, lorsqu'il est exposé à un champ magnétique. L’élément piézoélectrique se polarise et crée un champ électrique sous l’effet d’une contrainte mécanique. Ainsi, lorsque la bobine émettrice génère un champ magnétique, à la résonance, elle crée une déformation élastique du matériau magnétostrictif. Cette déformation mécanique est transmise à la couche piézoélectrique, dans laquelle apparaît un champ électrique, générant ainsi une tension électrique. Grâce à cette conversion magnéto-mécano-électrique, l'implant médical peut être alimenté ou rechargé. Pendant cette thèse, des transducteurs de différentes dimensions ont été réalisés et testés : 10mm et 16mm de diamètre, et de 2 à 5 mm d’épaisseur. Parmi de nombreux résultats de caractérisation, un résultat très intéressant montre qu’à diamètre égal les transducteurs les plus minces avec une fraction volumique de matériau magnétostrictif plus importante permettent d’atteindre des puissances plus importantes qu’avec des échantillons plus épais et dont la fraction volumique de matériau magnétostrictif plus faible. Ce résultat ouvre d’intéressantes perspectives pour la miniaturisation de transducteurs ME tout en conservant une efficacité satisfaisante dans le transfert d'énergie. Concernant les tests in vitro, les résultats obtenus sont très prometteurs, montrant des puissances suffisantes pour recharger un implant jusqu'à 20 mm de distance de la bobine émettrice, dans l'orientation la plus défavorable. Un tel résultat est impossible à obtenir dans le cas d’un système bobine-bobine dans la position la plus défavorable (bobines perpendiculaires).En conclusion, les résultats obtenus présentent des perspectives très intéressantes pour la télé-alimentation, en termes de dispositifs miniaturisés et d'adaptabilité à la localisation des dispositifs médicaux implantés
Nowadays, the market of implantable medical devices is very large and heterogeneous: of the order of 4,000 different device types tracked by the FDA in 2018 that can diagnose, monitor, and treat patients. Over the past decades, significant research has made to develop implanted systems more durable and less invasive. Despite dramatic progress in all directions, energy autonomy remains the Achilles heel of active implants. The most employed energy source remains today the single-use battery. For long-lasting implants such as pacemakers, the replacement of depleted batteries is necessary and requires a costly and invasive surgical procedure. To overcome these issues, different techniques have been investigated. The first approach consists in using the biomechanical energy available inside of the body, and the second is to transmit energy from outside of the human body. In the first case, it is possible, for example, to power the new generations of pacemakers using MEMS energy harvesting devices supplied by the heartbeat. In the second case, the wireless power transmission by induction between two coils (one in the implant, the other outside the body) is an increasingly widespread technology in the biomedical sector and in everyday life. The main difference between these two approaches is their power range: typically, a few microwatts for biomechanical energy harvesters, and milliwatts to watts for wireless power transmission. As part of this thesis, a new wireless power transmission technology has been developed. The considered system consists of two main blocks: the transmitter (out-body) and the receiver (located in the implant). The transmitter is a coil with no major constraints in terms of size and on-body position. The receiver is a magnetoelectric (ME) transducer. Investigating the use of a ME receiver, instead of the classical coil receiver, was in particular motivated by the willingness to reduce the alignment constraints of the classical coil-coil system, which is difficult to manage for implantable medical devices. The considered ME transducer is a composite made of piezoelectric and magnetostrictive layers. A magnetostrictive material has the property of mechanically deforming its structure, when exposed to a magnetic field. A piezoelectric material can be polarized and create an electric field under mechanical stress (direct effect). Therefore, the magnetic field, generated by the transmitter coil, induces an elastic deformation of the magnetostrictive material. This mechanical deformation is transmitted to the piezoelectric material, in which an electric field appears, generating an electric voltage across its electrodes. Thanks to the magnetic-mechanical-electrical energy conversion, achieved by the ME transducer, the medical implant can be wirelessly supplied or recharged. In this thesis, receivers with different sizes have been tested: 10 mm or 16 mm in diameter, and thickness comprised between 2 mm and 5 mm. Amongst numerous interesting experimental results, it was observed that thinner ME transducers with higher magnetostrictive volume ratio could generate higher electrical power than thicker samples with smaller magnetostrictive volume ratio. This result opens good prospects for the possibility of miniaturizing the ME transducer without losing efficiency in wireless power transfer. Concerning the in-vitro and phantom tests, the ME transducer exhibited very promising performances, converting enough power to recharge an implant up to 20 mm away from the transmitter coil, in the most unfavourable orientation. Such results are impossible to get using a coil-coil energy transmission system is the most unfavourable position (receiver perpendicular to the transmitter).In conclusion, the obtained results present very promising prospects for wireless energy transmission, in terms of miniaturised devices and adaptability to the localization of the implanted medical devices

Afin d'éviter une opération de remplacement de la batterie d'un dispositif biomédical, nous proposons d'utiliser une technique innovante de rechargement sans fils utilisant des matériaux magnétoélectriques. L'effet magnétoélectrique extrinsèque est principalement issu de la combinaison de deux phénomènes : piézoélectricité et magnétostriction. L'idée est de réaliser une transmission d'énergie sans fils basée sur les techniques d'induction en champ proche : on applique un champ magnétique, le récepteur qui servira de transducteur d'énergie sera composé d'un matériau magnétostrictif, qui, sous l'effet du champ magnétique va se déformer, les contraintes mécaniques sont transmises au matériau piézoélectrique qui se polarise. On mesure alors une tension électrique aux bornes du piézoélectrique qui peut ensuite servir à alimenter ou recharger un dispositif électronique. Cette thèse contribue au développement de cette technique en proposant des pistes d'améliorations de la puissance transmissible afin de pouvoir alimenter des capteurs avec un transducteur le plus petit possible. Pour ce faire, une modélisation par éléments finis 2D est présentée ainsi que des mesures de puissance et le développement du banc de caractérisation associé
In order to avoid surgery for battery replacement or recharge, we propose to use an innovative technique to wirelessly recharge the battery using magnetoelectric materials. The magnetoelectric effect is issued of two combined phenomena: piezoelectricity and magnetostriction. The idea is to achieve a wireless power transmission based on the near magnetic field techniques: the source energy is emitted via a magnetic field and the receptor which will transduce the energy is a magnetoelectric material. The magnetostrictive part of the magnetoelectric transducer is subjected to a stress due to the magnetic field. The stress is transmitted to the piezoelectric part which will produce an electric field. The electric voltage collected from the electrodes of the piezoelectric material will be used to power or recharge electronic devices. This thesis contributes to the development of this technique by proposing improving ways for energy transmission to powering sensors with the smallest transducer possible. An 2D finite element model his presented with power measurements and the characterizing bench associated

博士
國立清華大學
動力機械工程學系
104
This study presents a magnetostrictive type inductive sensing transducer which consisted of a planar coil, magnetic films, and a force supporting structure. As the force supporting structure deformed by an external load, the inverse magnetostriction effect would cause permeability changes of the magnetic films. Thus, the permeability changes as well as the external load can be detected by the inductance change of a planar inductor. To demonstrate the feasibility of the proposed transducer, pressure sensor designs which include the pressure supporting diaphragm, the planar coil and the patterns of magnetic films are fabricated and tested. Preliminary measurements show that the pressure sensor with 6 coil turns has sensitivities of 0.079%/kPa. In addition, based on the pattern design of the magnetic films, the gauge factor could be tuned from 55 to 852. Moreover, the wireless sensing capability of the magnetostrictive type inductive sensing CMOS-MEMS pressure transducers are also demonstrated using the post CMOS process. Metal and dielectric layers of CMOS process are employed to form the planar coil and the pressure supporting diaphragm, respectively. An additional magnetostrictive film was patterned by the post CMOS process. This study further proposes a new process scheme to fabricate a polymer structure with embedded metal on the silicon substrate. Based on the proposed scheme, a magnetostrictive type flexible tactile transducer consisting of a polymer structure with embedded Ni coil winding is successfully exploited.