No description available.

M.Ing. / The synchronous reluctance machine is a reasonably unknown type of machine. Recent developments have made it possible to deliver more power than an induction machine of similar size. It must, however, be noted that to accomplish this, the rotor profile design becomes complex and also expensive to manufacture. The aim of this project is to explore the possibility of controlling a synchronous reluctance machine `sensorlessly' (with no speed or position feedback sensors). The specific synchronous reluctance machine was made from an induction machine by machining a profile into the rotor cage of the induction machine. The required profile was designed using finite element analysis of the magnetic structure of the machine. A model of the machine was developed through using the direct and quadrature axis approach. With a model of the machine an estimator could be designed. This estimator was used to calculate the load angle of the machine by measuring the phase voltages and line currents and then estimating from these measurements the actual load angle. The estimator was designed for steady state conditions and gave sufficiently accurate values for the load angle under these conditions. The estimator was used as feedback in the torque control of the machine and it was shown that better results could be achieved with a better rotor profile. The partial cage of the induction machine present in the rotor made the machine more robust to changes in load. More research can be done on the modelling of the partial cage as well as the influence it has on the synchronous reluctance machine. Torque control and speed control were achieved with step changes in load of up to eighty percent of rated value. The performance of the machine was poor compared to an induction machine, but should improve with improvement in rotor profile design.

Recently discovered multiferroic nanoparticles (MFNs) known as magnetoelectric nanoparticles (MENs) promise to revolutionize next-generation biomedical diagnostic techniques and enable rapid and cost-effective screening of lethal diseases. Due to the quantum-mechanically caused intrinsic magnetoelectric (ME) effect, these nanoparticles display strongly coupled magnetic and electric moments and thus provide a unique pathway to monitor and optionally control intrinsic characteristics of bio organisms via application of external magnetic fields. Due to the ME effect, when placed in the microenvironment of a biomolecular sample, MENs’ magnetic properties change to reflect the molecular nature of the sample. Such an unprecedented intrinsic connection to cells and microorganism’s intrinsic characteristics can pave a way to a new diagnostic paradigm. A novel concept of portable biomolecular screening device based on continuous wave nuclear magnetic resonance is being studied to identify microorganisms like bacteria, virus and cancer cell lines. For the first time, MENs have been used to modify NMR spectra and thus enable identification of different cancer cell lines from each other as well as from their normal counterparts at the sub-cellular level. This approach can be used for both in vitro and in vivo diagnostics. In addition, blood samples of Pulmonary Arterial Hypertension (PAH) patients with severe heart and lung conditions were used to study the activity of MENs with prothrombin, the clotting factor of the blood. MENs has significant interaction with prothrombin. MENS can be used for diagnostics of several diseases associated with blood and cancer and it may be used as a therapeutic agent. The experiment proved that the MENs are safe and nontoxic carriers of therapeutic drugs.

Thesis (PhDEng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: The advent of new high energy product permanent magnet materials has opened great opportunities for novel electrical machine topologies with advantageous features such as high efficiency and high power/weight ratio. Amongst others, axial field permanent magnet (AFPM) machines with ironless stators are increasingly being used in power generation applications. Because of the absence of the core losses, a generator with this type of design can operate at a substantially high efficiency. Besides, the high compactness and disc-shaped profile make this type of machine particularly suitable for compact integrated power generation systems. Due to construction problems, the generator application of this type of machine has been limited to quite a low power range. There is a need to investigate the performance capability of this type of AFPM machine in the upper medium power level. The focus of this thesis is on the design optimisation of the air-cooled AFPM generator with an ironless stator. A design approach that directly incorporates the finite element field solution in a multi-dimensional optimisation procedure is developed and applied to the design optimisation of a 300 kW (at unity power factor) AFPM generator. To enable an overall design optimisation of the machine, different design aspects, such as the cooling capacity, the mechanical strength and eddy loss, are also studied in this research. To enable the free movement of the rotor mesh with respect to the stator mesh, the air-gap element originally proposed by Razek et. al. is derived for Cartesian coordinate systems. For minimising the large computation overhead associated with this macro element, a number of existing time-saving schemes have been utilised together with the derived Cartesian air-gap element. The developed finite element time-step model is applied to calculating the steadystate performance of the AFPM machine. Since the flux distribution in an AFPM machine is three dimensional by nature, calculating the eddy current loss by merely using a simple analytical method may be subject to a significant error. To overcome this problem, the two dimensional finite element field modelling is introduced to perform accurate field analysis. To exploit the full advantages of the twodimensional finite element modelling, a multi-layer approach is proposed, which takes into account the variation of the air-gap flux density in the conductors with regard to their relative positions in the air-gap. To account for the radial variation of the field, a multi-slice finite element modelling scheme is devised. The thermal analysis is an important aspect of the design optimisation of AFPM machines. From a design point of view, it is preferable to have a simple but effective method for cooling analysis and design, which can easily be adapted to a wide range of AFPM machines. In this thesis a thermofluid model of the AFPM machine is developed. The fluid flow model is needed for calculating the air flow rate, which is then used to find the convective heat transfer coefficients. These are important parameters in the subsequent thermal calculations. Experimental investigations have been carried out to verify each of the above-mentioned models/methods. With these models implemented, the design optimisation of an air-cooled ironless stator 300 kW (at unity power factor) AFPM generator is carried out. The performance measurements done on the fabricated prototype are compared in this thesis with predicted results. The study shows that the proposed design approach can be applied with success to optimise the design of the AFPM machine. The advantages of high power density, high efficiency, no cogging torque and good voltage regulation make this type of AFPM machine very suitable for power generator applications. The optimum steady-state performance of the AFPM machine shows that this machine with an ironless stator is an excellent candidate for high speed power generator applications, even in the upper medium power level. The good cooling capacity of this type of machine holds the promise of its being a self-cooled generator at high power ratings. / AFRIKAANSE OPSOMMING: Die uitvinding van nuwe hoë energiedigtheid permanent magneet materiale het groot geleenthede vir nuwe elektriese masjien topologië laat ontstaan met voordelige eienskappe soos hoë benuttingsgraad en hoë drywing/gewig verhouding. Onder andere word die aksiaalveld permanente magneet (AVPM) masjiene met kernlose stators toenemend gebruik vir elektriese generator toepassings. As gevolg van die afwesigheid van kernverliese kan 'n generator met hierdie tipe ontwerp teen 'n aansienlik hoë benuttingsgraad werk. Daarbenewens maak die hoë kompaktheid en skyfvorm-profiel die masjien in besonder geskik vir die ontwikkeling van kompak geïntegreerde drywing generator stelsels. As gevolg van konstruksie probleme is die toepassing van hierdie tipe masjien as generator beperk tot redelik lae drywingsgebiede. Dit is nodig om die werkverrigtingsvermoë van hierdie tipe AVPM masjien in die boonste medium drywingsgebied te ondersoek. Die fokus van hierdie tesis is op die ontwerp-optimering van 'n lugverkoelde AVPM generator met 'n kernlose stator. 'n Ontwerpsbenadering wat die eindige element veldoplossing in 'n multi-dimensionele optimeringsprosedure insluit, is ontwikkel en toegepas op die ontwerpsoptimering van 'n 300 kW (by eenheidsarbeidsfaktor) AVPM generator. Om 'n globale ontwerpsoptimering van die masjien te kan doen is verskillende ontwerpsaspekte soos die verkoelingskapasiteit, meganiese sterkte en werwelverliese ook in hierdie navorsing bestudeer. Om die vrye beweging van die rotormaas ten opsigte van die statormaas te verseker is die lugspleet-element, soos oorspronklik deur Razek et al voorgestel, afgelei vir Cartesiaanse koórdinaat stelsels. Om die lang berekeningstyd geassosieer met hierdie makro-element te minimaliseer is 'n aantal bestaande tydbesparende metodes saam met die ontwikkelde Cartesiaanse lugspleet-element gebruik. Die ontwikkelde eindige element tydstapmodel is toegepas om die bestendige werkverrigting van die AVPM masjien te bereken. Aangesien die vloedverspreiding in 'n AVPM masjien van nature drie-dimensioneel is, kan die berekening van die werwelstroomverliese tot aansienlike foute lei as eenvoudige analitiese metodes gebruik word. Om hierdie probleem te oorkom is twee-dimensionele eindige element modellering gebruik om akkurate veld-analise te doen. Om die volle voordele van die twee- dimensionele eindige element modellering te eksploiteer is 'n multi-laag benadering voorgestel wat die variasie van die lugspleetvloeddigtheid in die geleiers met betrekking tot hulle relatiewe lugspleetposisies in ag neem. Om voorsiening te maak vir die radiale variasie van die veld, is 'n multi-skyf eindige element modelleringstegniek ontwikkel. Die termiese analise is 'n belangrike aspek van die ontwerpsoptimering van AVPM masjiene. Vanuit 'n ontwerpsoogpunt is dit verkieslik om 'n eenvoudige maar tog effektiewe metode van verkoelingsanalise en -ontwerp te hê wat maklik toegepas kan word op 'n wye reeks van AVPM masjiene. In hierdie tesis word 'n termovloeimodel van die AVPM masjien ontwikkel. Hierdie vloeimodel is nodig vir die berekening van die lugvloeitempo, wat op sy beurt weer nodig is om die konveksie hitte-oordrag koëffisiënte te bepaal. Hierdie is belangrike parameters in die opvolgende termiese berekeninge. Eksperimentele ondersoek is uitgevoer om elkeen van die bogenoemde modelle en metodes te verifieer. Nadat hierdie modelle geïmplimenteer is, is die ontwerpsoptimering van 'n 300 kW (by eenheidsarbeidsfaktor) lugverkoelde kernlose stator AVPM generator uitgevoer. Die werkverrigtingmetings gedoen op 'n vervaardigde prototipe masjien, word in hierdie tesis vergelyk met voorspelde resultate. Daar word getoon dat die voorgestelde ontwerpsbenadering met sukses toegepas kan word om die ontwerp van die AVPM masjien te optimeer. Die voordele van hoë drywingsdigtheid, hoë benuttingsgraad, geen vertandingsdraaimomente en goeie spanningsregulasie maak hierdie masjien baie aantreklik vir generator toepassings. Die optimum bestendige werkverrigting van die AVPM masjien toon dat hierdie masjien met 'n kernlose stator 'n goeie kandidaat is vir hoë spoed generator toepassings, selfs in die boonste medium drywingsgebied. Die goeie verkoelingskapasiteit van hierdie tipe masjien hou die belofte in van'n selfverkoelde generator by hoë drywing aanslae.

No description available.

Thesis (PhDEng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: The advent of new high energy product permanent magnet materials has opened great opportunities for novel electrical machine topologies with advantageous features such as high efficiency and high power/weight ratio. Amongst others, axial field permanent magnet (AFPM) machines with ironless stators are increasingly being used in power generation applications. Because of the absence of the core losses, a generator with this type of design can operate at a substantially high efficiency. Besides, the high compactness and disc-shaped profile make this type of machine particularly suitable for compact integrated power generation systems. Due to construction problems, the generator application of this type of machine has been limited to quite a low power range. There is a need to investigate the performance capability of this type of AFPM machine in the upper medium power level. The focus of this thesis is on the design optimisation of the air-cooled AFPM generator with an ironless stator. A design approach that directly incorporates the finite element field solution in a multi-dimensional optimisation procedure is developed and applied to the design optimisation of a 300 kW (at unity power factor) AFPM generator. To enable an overall design optimisation of the machine, different design aspects, such as the cooling capacity, the mechanical strength and eddy loss, are also studied in this research. To enable the free movement of the rotor mesh with respect to the stator mesh, the air-gap element originally proposed by Razek et. al. is derived for Cartesian coordinate systems. For minimising the large computation overhead associated with this macro element, a number of existing time-saving schemes have been utilised together with the derived Cartesian air-gap element. The developed finite element time-step model is applied to calculating the steadystate performance of the AFPM machine. Since the flux distribution in an AFPM machine is three dimensional by nature, calculating the eddy current loss by merely using a simple analytical method may be subject to a significant error. To overcome this problem, the two dimensional finite element field modelling is introduced to perform accurate field analysis. To exploit the full advantages of the twodimensional finite element modelling, a multi-layer approach is proposed, which takes into account the variation of the air-gap flux density in the conductors with regard to their relative positions in the air-gap. To account for the radial variation of the field, a multi-slice finite element modelling scheme is devised. The thermal analysis is an important aspect of the design optimisation of AFPM machines. From a design point of view, it is preferable to have a simple but effective method for cooling analysis and design, which can easily be adapted to a wide range of AFPM machines. In this thesis a thermofluid model of the AFPM machine is developed. The fluid flow model is needed for calculating the air flow rate, which is then used to find the convective heat transfer coefficients. These are important parameters in the subsequent thermal calculations. Experimental investigations have been carried out to verify each of the above-mentioned models/methods. With these models implemented, the design optimisation of an air-cooled ironless stator 300 kW (at unity power factor) AFPM generator is carried out. The performance measurements done on the fabricated prototype are compared in this thesis with predicted results. The study shows that the proposed design approach can be applied with success to optimise the design of the AFPM machine. The advantages of high power density, high efficiency, no cogging torque and good voltage regulation make this type of AFPM machine very suitable for power generator applications. The optimum steady-state performance of the AFPM machine shows that this machine with an ironless stator is an excellent candidate for high speed power generator applications, even in the upper medium power level. The good cooling capacity of this type of machine holds the promise of its being a self-cooled generator at high power ratings. / AFRIKAANSE OPSOMMING: Die uitvinding van nuwe hoë energiedigtheid permanent magneet materiale het groot geleenthede vir nuwe elektriese masjien topologië laat ontstaan met voordelige eienskappe soos hoë benuttingsgraad en hoë drywing/gewig verhouding. Onder andere word die aksiaalveld permanente magneet (AVPM) masjiene met kernlose stators toenemend gebruik vir elektriese generator toepassings. As gevolg van die afwesigheid van kernverliese kan 'n generator met hierdie tipe ontwerp teen 'n aansienlik hoë benuttingsgraad werk. Daarbenewens maak die hoë kompaktheid en skyfvorm-profiel die masjien in besonder geskik vir die ontwikkeling van kompak geïntegreerde drywing generator stelsels. As gevolg van konstruksie probleme is die toepassing van hierdie tipe masjien as generator beperk tot redelik lae drywingsgebiede. Dit is nodig om die werkverrigtingsvermoë van hierdie tipe AVPM masjien in die boonste medium drywingsgebied te ondersoek. Die fokus van hierdie tesis is op die ontwerp-optimering van 'n lugverkoelde AVPM generator met 'n kernlose stator. 'n Ontwerpsbenadering wat die eindige element veldoplossing in 'n multi-dimensionele optimeringsprosedure insluit, is ontwikkel en toegepas op die ontwerpsoptimering van 'n 300 kW (by eenheidsarbeidsfaktor) AVPM generator. Om 'n globale ontwerpsoptimering van die masjien te kan doen is verskillende ontwerpsaspekte soos die verkoelingskapasiteit, meganiese sterkte en werwelverliese ook in hierdie navorsing bestudeer. Om die vrye beweging van die rotormaas ten opsigte van die statormaas te verseker is die lugspleet-element, soos oorspronklik deur Razek et al voorgestel, afgelei vir Cartesiaanse koórdinaat stelsels. Om die lang berekeningstyd geassosieer met hierdie makro-element te minimaliseer is 'n aantal bestaande tydbesparende metodes saam met die ontwikkelde Cartesiaanse lugspleet-element gebruik. Die ontwikkelde eindige element tydstapmodel is toegepas om die bestendige werkverrigting van die AVPM masjien te bereken. Aangesien die vloedverspreiding in 'n AVPM masjien van nature drie-dimensioneel is, kan die berekening van die werwelstroomverliese tot aansienlike foute lei as eenvoudige analitiese metodes gebruik word. Om hierdie probleem te oorkom is twee-dimensionele eindige element modellering gebruik om akkurate veld-analise te doen. Om die volle voordele van die twee- dimensionele eindige element modellering te eksploiteer is 'n multi-laag benadering voorgestel wat die variasie van die lugspleetvloeddigtheid in die geleiers met betrekking tot hulle relatiewe lugspleetposisies in ag neem. Om voorsiening te maak vir die radiale variasie van die veld, is 'n multi-skyf eindige element modelleringstegniek ontwikkel. Die termiese analise is 'n belangrike aspek van die ontwerpsoptimering van AVPM masjiene. Vanuit 'n ontwerpsoogpunt is dit verkieslik om 'n eenvoudige maar tog effektiewe metode van verkoelingsanalise en -ontwerp te hê wat maklik toegepas kan word op 'n wye reeks van AVPM masjiene. In hierdie tesis word 'n termovloeimodel van die AVPM masjien ontwikkel. Hierdie vloeimodel is nodig vir die berekening van die lugvloeitempo, wat op sy beurt weer nodig is om die konveksie hitte-oordrag koëffisiënte te bepaal. Hierdie is belangrike parameters in die opvolgende termiese berekeninge. Eksperimentele ondersoek is uitgevoer om elkeen van die bogenoemde modelle en metodes te verifieer. Nadat hierdie modelle geïmplimenteer is, is die ontwerpsoptimering van 'n 300 kW (by eenheidsarbeidsfaktor) lugverkoelde kernlose stator AVPM generator uitgevoer. Die werkverrigtingmetings gedoen op 'n vervaardigde prototipe masjien, word in hierdie tesis vergelyk met voorspelde resultate. Daar word getoon dat die voorgestelde ontwerpsbenadering met sukses toegepas kan word om die ontwerp van die AVPM masjien te optimeer. Die voordele van hoë drywingsdigtheid, hoë benuttingsgraad, geen vertandingsdraaimomente en goeie spanningsregulasie maak hierdie masjien baie aantreklik vir generator toepassings. Die optimum bestendige werkverrigting van die AVPM masjien toon dat hierdie masjien met 'n kernlose stator 'n goeie kandidaat is vir hoë spoed generator toepassings, selfs in die boonste medium drywingsgebied. Die goeie verkoelingskapasiteit van hierdie tipe masjien hou die belofte in van'n selfverkoelde generator by hoë drywing aanslae.

La série de RMn2O5 multiferroïques a été largement étudiée en raison de son fort couplagemagnéto-électrique. L’origine de la ferroélectricité a été clarifiée en tant que mécanisme de strictiond’échange. Comme les variations des distances interatomiques modifiées par la pression externe peuventgrandement affecter les propriétés multiferroïques, il est essentiel de comprendre l’origine microscopiquede cet effet.Nous avons déterminé la structure magnétique de la phase magnétique commensurable induite parla pression (PCM) et dessiné le diagramme de phase p − T. Sur la base d’un équilibre énergétique subtilentre l’interaction d’échange J1, l’interaction d’échange R-Mn J6 et l’anisotropie de la terre rare, nousavons proposé un mécanisme de stabilisation des différentes phases magnétiques en fonction de la pressionpour les différents composés avec R=Dy, Gd et Sm. L’augmentation de J1 sous pression à températureambiante obtenue grâce à l’étude par diffraction X confirme ce mécanisme. Une explication supplémentairea été proposée pour le cas particulier de PrMn2O5. Ces résultats ouvrent certainement la voie à unecompréhension complète de l’origine de l’influence de la pression dans la famille RMn2O5. / The series of multiferroic RMn2O5 has been extensively studied due to its strong magnetoelectriccoupling. The ferroelectricity origin has been clarified as the exchange striction mechanism. As thevariations of the interatomic distances modified by the external pressure can greatly affect the multiferroicproperties, it is essential to understand the microscopic origin of this effect.In this thesis, we have systematically studied the multiferroic properties of the RMn2O5 compounds byusing powder X-rays diffraction and powder neutron diffraction (PND) under pressure. We have determinedthe magnetic structure of the pressure induced commensurate magnetic (PCM) phase and drawn the p − Tphase diagram. Based on a subtle energy balance among the exchange interaction J1, the R-Mn exchangeinteraction J6 and the anisotropy of the rare earth, we have proposed a mechanism for stabilizing thedifferent magnetic phases as a function of the pressure for the different compounds with R = Dy, Gd andSm. The enhanced J1 under pressure at room temperature from the X-ray diffraction study further confirmsthis mechanism. An additional explanation has been proposed for the special case of the PrMn2O5. Theseresults certainly pave the way to fully understand the origin of the pressure influence in the RMn2O5 family

No description available.

Magnetoelectric (ME) interactions in matter correspond to the appearance of magnetization by means of an electric field (direct effect) or the appearance of electric polarization by means of a magnetic field (converse effect). The composite laminates which possess large ME coefficient, have attracted much attention in the field of sensors, modulators, switches and phase inverters. In this thesis, we report on the ME performances of the bi- and tri- layered composites. It is shown that their ME couplings can be achieved by combining magnetostrictive and piezoelectric layers. A model based on a driven damped oscillation is established for the piezoelectric/magnetostrictive laminated composite. It is used to simulate the mechanical coupling between the two layers. In addition, we report that the ME coupling can be achieved without magnetic phase but only with eddy current induced Lorentz forces in the metal electrodes of a piezoelectric material induced by ac magnetic field. The models based on the Lorentz effect inducing ME coupling in PZT unimorph bender, polyvinylidene fluoride (PVDF) film and PZT ceramic disc are thus established. The results show the good sensitivity and linear ME response versus dc magnetic field change. Thus, the room temperature magnetic field detection is achievable using the product property between magnetic forces and piezoelectricity. Besides, we report on the electrostrictive performance of cellular polypropylene electret after high-voltage corona poling. We use the Surface Potential test, Thermal Stimulated Depolarization Current experiment and Differential Scanning Calorimetry experiment to analyse its charge storage mechanism. The result show that the electrostrictive coefficient and relative permittivity of the charged samples increase. Last but not least, in order to explain this phenomenon, a mathematic model based on the charged sample has been established.

Les capteurs magnéto-électrique (ME) sont une alternative prometteuse pour mesurer de faibles signaux magnétiques. Précédemment le choix était généralement de déposer des couches minces magnétostrictives sur un matériau piézoélectrique massif conduisant à des systèmes macroscopiques de taille milllimétrique. L’intégration de ces systèmes dans des MEMS (micro-electro-mechanical systems) requiertà la fois de résoudre les problèmes d’intégration de matériaux actif sur silicium, et de mesurer des petits signaux étant donné l’importante réduction de la réponse du système lorsqu’il est miniaturisé.Dans cette optique, le premier objectif de ce travail de thèse a été d’intégrer un matériau piézoélectrique sur un substrat de silicium tout en conservant une excellente qualité cristalline. Pb(Zr ₀ , ₅ ₂Ti ₀ ,₄₈)O₃ (PZT) a été retenu pour ces excellente propriétés piézoélectriques. L’intégration de la couche mince ce fait sur silicium qui est le substrat de prédilection pour la fabrication de microsystèmes avec les procédés microélectroniques standards. La qualité cristalline des matériaux actifs est directement corrélée aux couches d'adaptation utilisées pour obtenir une bonne qualité cristalline sur silicium. Pour cel l'intégration d'une tricouche composée de zircone stabilisée à l'yttrium (YSZ), d'oxyde de cérium (CeO₂) et de SrTiO₃ permet ensuitela croissance des pérovskites d'intérêt pour le dispositif. Le choix de l’électrode conductrice inférieure (SrRuO₃ ou La ₀ ,₆₆Sr₀₃₃MnO₃ dans le cas présent) permet de contrôler l’orientation de la maille de PZT.Une première étude des propriétés piézoélectriques de la couche mince de PZT sous la forme d’une poutre libre pour son intégration dans un système magnétoélectrique a été réalisé. La mesure de la déformation de la poutre induite par l'application d'une tension électrique permet d'extraire un coefficient d₃₁ de -53pmV⁻¹, valeur inférieure au matériau massif mais à l'état de l'art dans ce type de dispositif. Dans une seconde étape, l’utilisation de la poutre comme résonateur à été étudiée. L’étude dynamique du système a permis d'obtenir la fréquence de résonance et le facteur de qualité. Le déplacement de la fréquence caractéristique du système en fonction d'une contrainte induite par une tension DC a été investigué. Enfin, l'ajout d'une couche de matériau magnétostrictif (TbFeCo) sur la poutre a finalisé la structure du capteur. Le capteur ainsi obtenu a été caractérisé et une sensibilité d’une dizaine de micro Tesla a été obtenue. / Magneto-electric (ME) sensors have been demonstrated as a promising alternative for the detection of weak magnetic signals with high sensitivity. To date, most applications focused on the use of bulk piezoelectric materials on which magnetostrictive thin films are deposited leading to millimeter-sized devices. The integration of such devices into micro-electro-mechanical systems (MEMS), bringing smaller size and lower power consumption, involves addressing several scientific issues ranging from the integration of active materials on silicon to the strong reduction in amplitude of generated signals related to the size reduction of the sensor.In this context, the first goal of this thesis work was to integrate high crystalline quality piezoelectric thin films on silicon.Pb(Zr ₓTi ₁ ₋₁)O₃ (PZT) with a morphotropic composition (x=0.52) having high electromechanical coupling factor was chosen. Silicon is a necessary template as it allows for the use of conventional clean room processes for the realization of the microsystem. The crystalline quality of the active films is directly linked to the buffer layers that promote the crystalline growth on silicon. For this purpose, Yttria-stabilized Zirconia (YSZ) was used in combination with CeO₂ and SrTiO₃ to allow further growth of epitaxial perovskites. The choice of the bottom electrode material (SrRuO₃ or La ₀ ,₆₆Sr₀₃₃MnO₃ in this work) further tunes the crystalline orientation of the PZT layer.To probe the potential of such PZT thin films for ME devices, the first step was to characterize the electromechanical properties of this material in a free standing cantilever structure. Under an applied electric field, the measured displacement of the epitaxial PZT-based cantilevers is characterized by a coefficient d₃₁ =-53pmV⁻¹ , a reduced value with respect to the bulk material but that can be enhanced by further optimizing the film growth. The second step consists in ascertaining the ability of the cantilever to be used as resonator. For that purpose, first characterizations of oscillators have been performed to extract the resonant frequencies and the associated quality factors. Then, the resonant frequency shift with DC bias-induced stress was measured. Finally, a magnetostrictive layer of TbFeCo was added on the PZT cantilevers to sense magnetic field based on the ME effect. The resulting resonant frequency shift with external applied magnetic field was characterized with a typical sensitivity of 10’s of µT.