In this modern age of information, the demands on data transmission networks for greater capacity, and mobile accessibility are increasing drastically. The increasing demand for mobile access is evidenced by the proliferation of wireless systems such as mobile phone networks and wireless local area networks (WLANs). The frequency range over which an oxygen resonance occurs in the atmosphere (~58-62 GHz) has received recent attention as a possible candidate for secure high-speed wireless data networks with a potentially high degree of frequency reuse. A significant challenge in implementing data networks at 60 GHz is the manufacture of low-cost RF transceivers capable of satisfying the system requirements. In order to produce transceivers that meet the additional demands of high-volume, mobility, and compactness, monolithic millimeter wave integrated circuits (MMICs) offer the most practical solution. In the design of radio tranceivers with a high degree of integration, the receiver front-end is typically the most critical component to overall system performance. High-performance low-noise amplifiers (LNAs) are now realizable at frequencies in excess of 100 GHz, and a wide variety of mixer topologies are available that are capable of downconversion from 60 GHz. However, local oscillators (LOs) capable of providing adequate output power at mm-wave frequencies remain bulky and expensive. There are several techniques that allow the use of a lower frequency microwave LO to achieve the same RF downconversion. One of these is to employ a subharmonic mixer. In this case, a lower frequency LO is applied and the RF mixes with a harmonic multiple of the LO signal to produce the desired intermediate frequency (IF). The work presented in this thesis will focus on the development of a GaAs MMIC 4-X subharmonic mixer in Finite Ground Coplanar (FGC) technology for operation at 60 GHz. The mixer topology is based on an antiparallel Schottky diode pair. A discussion of the mechanisms behind the operation of this circuit and the methods of practical implementation is presented. The FGC transmission lines and passive tuning structures used in mixer implementation are characterized with full-wave electromagnetic simulation software and 2-port vector network analyzer measurements. A characterization of mixer performance is obtained through simulations and measurement. The viability of this circuit as an alternative to other high-frequency downconversion schemes is discussed. The performance of the actual fabricated MMIC is presented and compared to currently available 60 GHz mixers. One particular MMIC design exhibits an 11.3 dB conversion loss at an RF of 58.5 GHz, an LO frequency of 14.0 GHz, and an IF of 2.5 GHz. This represents excellent performance for a 4X Schottky diode mixer at these frequencies. Finally, recommendations toward future research directions in this area are made. / Master of Science

This thesis aims to investigate the acoustic properties of ultrasound contrast agents (UCAs) at high ultrasound frequencies. In recent years, there has been increasing development in the use of high frequency ultrasound in the fields of preclinical, intravascular, ophthalmology and superficial tissue imaging. Although research studying the acoustic response of UCAs at low diagnostic ultrasonic frequencies has been well documented, quantitative information on the acoustical properties of UCAs at high ultrasonic frequencies is limited. In this thesis, acoustical characterisation of three UCAs was performed using a preclinical ultrasound scanner (Vevo 770, VisualSonics Inc., Canada). Initially the acoustical characterisation of five high frequency transducers was measured using a membrane hydrophone with an active element of 0.2 mm in diameter to quantify the transmitting frequencies, pressures and spatial beam profiles of each of the transducers. Using these transducers and development of appropriate software, high frequency acoustical characterisation (speed and attenuation) of an agar-based tissue mimicking material (TMM) was performed using a broadband substitution technique. The results from this study showed that the acoustical attenuation of TMM varied nonlinearly with frequency and the speed of sound was approximately constant 1548m·s-1 in the frequency range 12-47MHz. The acoustical properties of three commercially available lipid encapsulated UCAs including two clinical UCAs Definity (Lantheus Medical Imaging, USA) and SonoVue (Bracco, Italy) and one preclinical UCAs MicroMarker (untargeted) (VisualSonics, Canada) were studied using the software and techniques developed for TMM characterisation. Attenuation, contrast-to-tissue ratio (CTR) and subharmonic to fundamental ratio were measured at low acoustic pressures. The results showed that large off-resonance and resonant MBs predominantly contributed to the fundamental response and MBs which resonated at half of the driven frequency predominantly contributed to subharmonic response. The effect of needle gauge, temperature and injection rate on the size distribution and acoustic properties of Definity and SonoVue was measured and was found to have significant impacts. Acoustic characterisations of both TMM and UCAs in this thesis extend our understanding from low frequency to high frequency ultrasound and will enable the further development of ultrasound imaging techniques and UCAs design specifically for high frequency ultrasound applications.

Depuis leur introduction, les agents de contraste ont révolutionné l'imagerie échographique. Ils sont composés de microbulles gazeuses, qui injectés par voie intraveineuse dans le sang, ils améliorent l'image échographique. Une autre application pour laquelle les caractéristiques physiques des agents de contraste sont exploitées est l'imagerie ciblée. Une approche basée sur l'utilisation de ligands intégrés à la paroi des microbulles, celles-ci adhérent aux facteurs de surfaces moléculaires surexprimés par les cellules endothéliales qui tapissent la paroi interne des vaisseaux sanguins. Pour pouvoir distinguer ces microbulles de celles qui circulent librement, elles doivent réfléchir un signal acoustique suffisamment intense. Cependant, le faible taux d'adhérence des microbulles engendre une réduction du signal acoustique. Pour résoudre ce problème, il est important de déterminer l'effet des parois sur leurs dynamiques acoustiques. Dans cette thèse, nous avons étudié l’effet des parois élastiques sur le comportement dynamique des microbulles constituant les agents de contraste. Dans un premier temps, un modèle théorique représentant une paroi avec une épaisseur finie a été développé. Il a été démontré que l’amplitude de l’écho rétrodiffusé par une microbulle proche d’une paroi avec une épaisseur finie est inférieure à celui d’une microbulle se trouvant dans un fluide infini. D'autres parts, pour représenter la paroi d’un vaisseau sanguin, les propriétés mécaniques de la paroi élastique ont été intégrées au modèle. Il a été observé que la fréquence de résonance d’une microbulle proche d’une paroi est supérieure à celle dans un fluide infini. Par la suite, nous avons étudié l’effet de trois types de parois sur le comportement d’une microbulle parmi lesquelles la paroi d'OptiCell communément utilisée en expérimentations ultrasonores. Les résultats ont montré que la microbulle proche de la paroi d’OptiCell diffuse un écho supérieur à celui de la microbulle éloignée de la paroi, lorsque la fréquence d’excitation est au-dessus de sa fréquence de résonance. Nous avons constaté aussi que les petites bulles sont plus sensibles à la proximité de la paroi. Par la suite, nous avons développé un modèle décrivant une microbulle attachée à une paroi élastique. Nous avons montré que le contact direct de la bulle avec la paroi induit une diminution de l'écho par rapport à la même bulle dans un liquide infini. Le contact direct de la bulle avec la paroi engendre une augmentation de la fréquence de résonance part rapport à une bulle sans contact direct. Enfin, une étude expérimentale a montré l'avantage de l'imagerie sous-harmonique pour différencier les microbulles attachées des microbulles libres. / Since they were introducted, contrast agents have revolutionized the ultrasound imaging. They are composed of tiny gaseous microbubbles and when injected intravenously into the blood, they improve the ultrasound image. Targeted imaging is another application based on the physical characteristics of contrast agents. This approach is based on the ligands incorporation into the microbubbles shell. The microbubble attach to the molecular factors overexpressed by endothelial cells, covering the inner wall of blood vessels. To distinguish these microbubbles from those freely circulating, attached microbubble have to produce an acoustic signal that is sufficiently strong. However, the low microbubbles adhesion induces a decrease of the acoustic signal. To make it possible, it is important to determine the effect of the elastic wall on their acoustic response. This thesis aimed to study the effect of elastic walls on the ultrasonic behavior of targeted microbubbles. First, a theoretical model describing a wall with finite thickness was developed. It has been shown that the scattered echo amplitude by a microbubble near a wall with finite thickness is small in comparison to the echo from a microbubble located in an infinite fluid. Furthermore, and in order to account for the effect of blood vessel wall, the mechanical properties of the wall have been incorporated into the model. The results showed that the resonane frequency of a microbubble near the wall is higher than the resonanace of the same microbubble in an infinite medium. Subsequently, we studied the effect of three types of walls on the microbubble behavior including the wall of OptiCell chamber which is commonly used in ultrasonic experiments. We have shown that microbubbles near the OptiCell wall diffuses a higher echo than those far from the wall when the excitation frequency is above the microbubble resonance frequency. On the other side, we observed that small microbubbles to the presence of the wall. Afterward, we developed a model describing a microbubble attached to the wall. We have shown that the microbubble in direct contact with the wall induces a decrease of the echo amplitude compared to the same bubble in infinite liquid. Moreover, the direct contact of the bubble with the wall generates an increase of the resonance frequency relative to a bubble without direct contact. Finally, an experimental study has shown the advantage of the subharmonic imaging to differentiate attached microbubbles from the free ones.

This thesis presents the results of studies on the problem of subharmonic oscillations in nonlinear Paul trap mass spectrometry. The objective of this thesis is to determine whether the subharmonic oscillations of ions in the trap could in any way affect the quality of mass spectrum in resonance ejection experiments. This is accomplished by studying the existence and stability criteria of these oscillations. This study is done for two casesone in which the auxiliary excitation frequency is close to thrice the ion axial secular frequency and other in which it is close to twice the ion axial secular frequency. Initially, the equations describing the ion motion in the presence of auxiliary excitation are derived. The equations describing the ion motion are then brought into a form easily amenable to analysis by techniques of perturbation theory. The necessary background and definitions to understand the basis for the thesis, along with a survey of results obtained in relevant areas in mass spectrometry and nonlinear dynamics is then developed. The first problem is the study of subharmonic oscillations when the auxiliary excitation frequency is in the vicinity of thrice the ion axial secular frequencies taken up. The application of the multiple time scales technique to the equations describing ion motion gives the slow flow equations, that describe the evolution of amplitudes of axial and radial oscillations. The expression for the steady state amplitudes of these oscillations are then derived. From these expressions the conditions for the existence of the oscillations are obtained in terms of the auxiliary amplitude and the frequency detuning. This is then followed by a detailed stability analysis for the subharmonic oscillation with a given amplitude and phase. The study ends with the discussion of the results obtained, the pertinent numerical studies and the relevance of this study to mass spectrometry. The second study is regarding the problem of subharmonic oscillations when the auxiliary excitation frequency is close to twice the ion axial secular frequency is analyzed. When PoincareLindstedt’s method is applied to the ion motion equations, the amplitude frequency relationship that describes the relation between the steady state subharmonic oscillation amplitude and the frequency detuning is obtained. The variation of the oscillation amplitude with the frequency detuning is then studied. Then follows the analysis of stability. The stability of subharmonic oscillation is analyzed using the results from the standard analysis of Hill’s equation of fourth order. This study ends with the discussion of the results obtained in the context of mass spectrometry. Finally, a summary of the results obtained is discussed.

The task of this master’s thesis is design and implementation subharmonic mixer for the microwave band. Subharmonic mixer is based on the principle of antiparallel diode. In the first two parts are theoretically described mixers (subharmonic mixer) and topology suitable for implementation. Another work describes the design subharmonic mixer. The proposal is implemented in the program Ansoft designer. DPS is created in Eagle or in Ansoft Designer. The mixer is designed and implemented first on the lower frequency and consequently at higher frequencies (24,048 GHz and 47,088 GHz). Work also includes the measurement results of the mixer.

The task of this master’s thesis is design and implementation subharmonic mixer for the microwave band. Subharmonic mixer is based on the principle of antiparallel diode. In the first two parts are theoretically described mixers (subharmonic mixer) and topology suitable for implementation. Another work describes the design subharmonic mixer. The proposal is implemented in the program Ansoft designer. DPS is created in Eagle or in Ansoft Designer. The mixers are designed and implemented first on the lower frequency and consequently at higher frequencies (24,048 GHz and 47,088 GHz). Work also includes the measurement results of the mixers.

Ultrasound has been established as one of the most widely used imaging modalities for diagnostic purposes, due to the several advantages it provides in comparison with other techniques. Hence, ways to further improve the confidence in diagnoses provided by ultrasound are constantly being investigated. One of them is the introduction of Ultrasound Contrast Agents, which can enhance the weak echoes produced by the small vessels, improving the imaging performance. In this study, a setup was created and six ultrasound imaging techniques were implemented by using the Verasonics Research System®, in order to take advantage of the different behavior between the tissue and the Polyvinyl-Alcohol microbubbles, when exposed to ultrasound. These were: Fundamental B-mode, Ultraharmonic, PulseInversion, Subharmonic Pulse Inversion, Ultraharmonic Pulse Inversion, Combination of the Sub- and Ultraharmonic Pulse Inversion. For the assessment of the bubbles’ response, the amplitude spectra were used, which showed a limited detection around the ultraharmonic region. For the evaluation of the imaging performance of the techniques, the Contrast-to-Tissue (CTR) and Contrast-to-Noise Ratios (CNR) were calculated. The Combination of the Sub- and Ultraharmonic Pulse Inversion reported the highest imaging performance among all the techniques. A comparison with previous articles provided a similar pattern in terms of CTR. / Technology

The natural dynamics are not ideal or linear. To understand their complex behavior, we needs to study the nonlinear dynamics in more simple models. This thesis is consist of two main setups. Both setups are simplified models for the behavior occurs in the complex systems. We studied in both systems the same nonlinear dynamics such as higher-harmonics, sub-harmonics, solitary waves,...etc. In Chapter (2), the propagation of nonlinear waves in a lattice of repelling particles is studied theoretically and experimentally. A simple experimental setup is proposed, consisting in an array of coupled magnetic dipoles. By driving harmonically the lattice at one boundary, we excite propagating waves and demonstrate different regimes of mode conversion into higher harmonics, strongly in influenced by dispersion. The phenomenon of acoustic dilatation of the chain is also predicted and discussed. The results are compared with the theoretical predictions of FPU equation, describing a chain of masses connected by nonlinear quadratic springs. The results can be extrapolated to other systems described by this equation. We studied theoretically and experimentally the generation and propagation of kinks in the system. We excite pulses at one boundary of the system and demonstrate the existence of kinks, whose properties are in very good agreement with the theoretical predictions, that is the equation that approaches, under the conditions of our experiments, the one corresponding to full model describing a chain of masses connected by magnetic forces. The results can be extrapolated to other systems described by this equation. Also, In the case of a lattice of finite length, where standing waves are formed, we report the observation of subharmonics of the driving wave. In chapter (3), we studied the propagation of intense acoustic waves in a multilayer crystal. The medium consists in a structured fluid, formed by a periodic array of fluid layerswith alternating linear acoustic properties and quadratic nonlinearity coefficient. We presents the results for different mathematicalmodels (NonlinearWave Equation,Westervelt Equation and Constitutive equations). We show that the interplay between strong dispersion and nonlinearity leads to new scenarios of wave propagation. The classical waveform distortion process typical of intense acoustic waves in homogeneous media can be strongly altered when nonlinearly generated harmonics lie inside or close to band gaps. This allows the possibility of engineer a medium in order to get a particular waveform. Examples of this include the design of media with effective (e.g. cubic) nonlinearities, or extremely linear media. In chapter (4), the oscillatory behavior of a microbubble is investigated through an acousto-mechanical analogy based on a ring-shaped chain of coupled pendula. Observation of parametric vibration modes of the pendula ring excited at frequencies between 1 and 5 Hz is considered. Simulations have been carried out and show spatial mode, mixing and localization phenomena. The relevance of the analogy between a microbubble and the macroscopic acousto-mechanical setup is discussed and suggested as an alternative way to investigate the complexity of microbubble dynamics. / La dinámica natural no es ideal ni lineal. Para entender su comportamiento complejo, necesitamos estudiar la dinámica no lineal en modelos más simples. Esta tesis consta de dos configuraciones principales. Ambas configuraciones son modelos simplificados de el comportamiento que se produce en los sistemas complejos. Estudiamos en ambos sistemas la misma dinámica no lineal como son la generación de armónicos superiores, los sub-armónicos, las ondas solitarias, etc. En elCapítulo (2), se estudia, tanto teórica comoexperimentalmente, la propagación de ondas no lineales en sistemas periodicos de partículas acopladas mediante fuerzas repulsivas. Se propone una configuración experimental simple, que consiste en una matriz de dipolos magnéticos acoplados. Inyectando armónicamente la señal en un extremo, excitamos ondas de propagación y demostramos diferentes regímenes de conversión de modos en armónicos, fuertemente influenciados por la dispersión. También se predice y se discute el fenómeno de dilatación acústica de la cadena. Los resultados se comparan con las predicciones teóricas de la ecuación FPU, describiendo una cadena de masas conectadas por muelles cuadráticos no lineales. Los resultados pueden ser extrapolados a otros sistemas descritos por esta ecuación. Estudiamos también teórica y experimentalmente la generación y propagación de kinks. Excitamos pulsos en la frontera del sistema y demostramos la existencia de kinks cuyas propiedades están en muy buen acuerdo con las predicciones teóricas, es decir, con la ecuación que aproxima bajo las condiciones de nuestros experimentos la correspondiente al modelo completo que describe un cadena de masas conectadas por fuerzas magnéticas. Los resultados pueden ser extrapolados a otros sistemas descritos por esta ecuación. Además, en el caso de una red finita, donde se forman ondas estacionarias, describimos la observación de subarmónicos del armónico principal. En el capítulo (3), estudiamos la propagación de ondas acústicas intensas en un cristal multicapa. El medio consiste en un fluido estructurado, formado por un conjunto periódico de capas fluidas con propiedades acústicas lineales alternas y coeficiente de no linealidad cuadrática. Presentamos los resultados de diferentes modelos matemáticos (ecuación de ondas no lineal, ecuación de Westervelt y ecuaciones constitutivas). Mostramos que la interacción entre la fuerte dispersión y la no linealidad conduce a nuevos escenarios de propagaciónde ondas. El proceso de distorsión de la onda clásica, típico de las ondas acústicas intensas en medios homogéneos, puede ser alterado de forma importante cuando los armónicos generados no linealmente se encuentran dentro o cerca del gap. Esto permite la posibilidad de diseñar un medio con el fin de obtener una forma de onda en particular. Ejemplos de esto incluyen el diseño demedios con no linealidad efectiva (por ejemplo, cúbica) o medios extremadamente lineales. En el capítulo (4), el comportamiento oscilatorio de una microburbuja se investiga a través de una analogía acusto-mecánica basada en una cadena en forma de anillo de péndulos acoplados. Se estudian los modos de vibración paramétrica del anillo pendular excitado a frecuencias entre 1 y 5 Hz. Se han llevado a cabo simulaciones que muestran la presencia de modos espaciales, mixtos y fenómenos de localización. Se discute la relevancia de la analogía entre una microburbuja y la configuración macroscópica acústico-mecánica y se sugiere como una vía alternativa para investigar la complejidad de la dinàmica de microburbujas. / La dinàmica natural no és ideal ni tampoc lineal. Per entendre el seu comportament complex, es necessita estudiar la dinàmica no lineal dels models més simples. Aquesta tesi consisteix en l'estudi de dues configuracions principals, que són models simplificats del comportament que es produeix en els sistemes complexos. Estudiem en ambdós sistemes la mateixa dinàmica no lineal, com és la generació d'harmònics superiors, sub-harmònics, ones solitàries, etc. En el capítol (2), estudiem, tant teòrica com experimentalment, la propagació de les ones no lineals en sistemes periòdics de partícules acoblades mitjançant forces repulsives. Es proposa una configuració experimental simple, que consisteixen en una matriu de dipols magnètics acoblats. En conduint harmònicament la xarxa en un límit, excitemla propagació de les ones i demostrem diferents règims de conversió de modes en harmònics més alts, força influenciada per la dispersió. El fenomen de la dilatació acústica de la cadena també es prediu i es discuteix. Els resultats es comparen amb les prediccions teòriques que descriu una cadena de masses conectades per molls quadràtics no lineals. Els resultats es poden extrapolar a altres sistemes descrits per aquesta equació. Hem estudiat teòrica i experimentalment la generació i propagació de Kinks. Excitem polsos a la frontera del sistema i demostrem l'existència d'Kinks, les propietats desl quals estan en molt bon acord amb les prediccions teòriques, és a dir, de l'equació que aproxima sota les condicions dels nostres experiments la corresponent al model complet que descriu un cadena demasses connectades per forcesmagnètiques. Els resultats es poden extrapolar a altres sistemes descrits per aquesta equació. A més, en el cas d'una xarxa finita, on es formen ones estacionàries, descrivim l'observació de subarmónicos de l'harmònic principal. En el capítol (3), s'estudia la propagació d'ones acústiques intenses en un medi multicapa. El medi consisteix en un fluid estructurat, format per una matriu periòdica de capes de fluid amb l'alternança de propietats acústiques lineals i coeficient de no linealitat de segon grau. Es presenten els resultats per a diferents models matemàtics no lineals (equació d'ones no lineal, equació de Westervelt i les equacions constitutives). Es demostra que la interacciò entre la forta dispersió i no linealitat condueix a nous escenaris de propagació de l'ona. El procés de distorsió en formad'ona clàssica, típica de les ones acústiques intenses en medis homogenis, es pot alterar de manera significativa quan els harmònics generats de forma no lineal es troben dins o a prop del gap. Això obri la possibilitat de dissenyar unmedi per tal d'obtenir una forma d'ona particular. Exemples d'això inclouen el disseny delsmedis amb una no linealitat efectiva (per exemple cúbica), o medis extremadament lineals. En el capítol (4), el comportament oscilatori d'una micro-bombolla és investigat a través d' una analogia acústica-mecànica basada en una cadena en forma d'anell de pèndols acoblats. Es considera l'observació dels modes de vibració paramètriques de l'anell pendular excitat amb freqüències entre 1 i 5 Hz. S'han dut a terme simulacions que mostren la presència de moes espacilas, mixtes i fenòmens de localització. Es discuteix la relevància de l'analogia entre les microbambolles i la configuració macroscòpica acústica-mecànica i es suggereix una formaalternativa per a investigar la complexitat de la dinàmica demicrobombolles. / Mehrem Issa Mohamed Mehrem, A. (2017). Nonlinear acoustics in periodic media: from fundamental effects to applications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/80289

The complexity of vehicular communication and radar sensing becomes increasingly complex with the growing demand for advanced driver-assistant systems in the automotive industry. Researchers are currently looking into combining communication and sensing by utilizing traditional communication waveforms in the mmWave radar bands to mitigate congestion and inter-radar interference. This thesis investigates a local-oscillator (LO) phase-shifting architecture to simplify the implementation of D-band (110–170 GHz) phased arrays for such applications. The constructed signal chain includes four 8–12-GHz voltage-controlled analog phase shifters, each mounted on the LO feed of a quadrature subharmonic upconverter, and a four-channel slot antenna. Through careful calibration of the analog control voltages, the 100-MHz baseband feed, and the LO distribution, antenna measurements in an anechoic chamber resulted in a beambook with antenna diagrams at seven angles from −30° to +30°. The gain was between 10.78 dB and 12.80 dB relative to the gain of one element, and the sidelobe levels were less than 8.9 dB. / Fordononsindustrins ökade efterfrågan på avancerade assistansystem gör framtidens kommunikation och radaravkänning allt mer komplex. Forskare undersöker just nu möjligheten att integrera kommunikation och radar genom att använda traditionella vågformer på millimetervågsfrekvenser för att förhindra nätverksträngsel och interferens mellan närliggande sensorer. Detta examensarbete undersöker möjligheten att fasstyra en radarantenn genom att skifta fasen på sändarens lokaloscillator (LO) och på så sätt förenkla konstruktionen av fasade gruppantenner på D-bandet (110–170 GHz). Signalkedjan bestod av fyra spänningsstyrda 8–12 GHz-fasskiftare, var och en monterade på LO-matningen till en subharmonisk mixer, samt en fyrkanals slitsantenn. Genom noggrann kalibrering av kontrollspänningar, 100 MHz-basbandsmatning och LO-distribution kunde antennmätningar i en ekofri kammare påvisa de önskade antenndiagramen för sju vinklar mellan −30° och +30°. Förstärkningen i förhållande till ett antennelement var mellan 10.78 dB och 12.80 dB och sidlobsnivåerna var lägre än 8.9 dB.

Dans l’objectif de limiter les effets destructeurs de l’implosion de bulles de cavitation ultrasonore, un régime d’oscillations stables de bulles doit potentiellement être visé pour des applications thérapeutiques sensibles comme l’ouverture de la barrière hémato-encéphalique. Cependant, garantir une activité d’oscillations stables est difficile de par le caractère stochastique de la cavitation ultrasonore, et de la coexistence de bulles oscillantes (cavitation stable) et implosantes (cavitation inertielle) au sein d’un nuage de bulles. Il est donc nécessaire de contrôler spatialement et temporellement le phénomène de cavitation en discriminant les régimes de cavitation stable ou inertielle, au cours de la durée d’un tir ultrasonore, et ce en régime pulsé. Dans une première étude, la dynamique d’un nuage de bulles monodisperses et uniformément réparties dans l’espace met en évidence l’effet de l’interaction entre bulles sur le seuil de cavitation stable : il s’abaisse en pression et la fréquence de résonance des bulles se décale en fonction de la densité de bulle. Il est ainsi montré qu’il existe une densité de bulle optimale pour l’émission de la composante sous-harmonique. Ensuite, une stratégie de contrôle est développée, basée sur une boucle de rétroaction régulant la signature acoustique d’un régime donné de cavitation. L’utilisation de la stratégie d’asservissement permet de discriminer les régimes de cavitation stable et inertielle au cours du temps, mais aussi de garantir une activité de cavitation plus stable temporellement, plus reproductible, et ce pour des énergies acoustiques moyennes délivrées inférieures. Enfin, le processus de contrôle est utilisé expérimentalement pour des applications in-vitro de sonoporation cellulaire. Tout d’abord, une étude de sonoporation en cavitation inertielle régulée met en évidence l’amélioration de la reproductibilité des taux de sonoporation obtenus, et la possibilité de s’affranchir de l’utilisation d’agents de contraste comme agents de nucléation. Ensuite, une étude en cavitation stable régulée met en évidence la possibilité de sonoporer des cellules en limitant les activités de cavitation inertielle, et donc potentiellement en limitant la lyse cellulaire / In the aim of limiting the destructive behavior of collapsing cavitation bubbles, an exclusively stable cavitation state is targeted for sensitive therapeutics applications like blood-brain barrier opening. Ensuring a stable cavitation regime is complex because of (i) the coexistence of stably oscillating bubbles and collapsing bubbles in the same bubble cloud, and (ii) the stochastic behavior of the phenomenon during time. Therefore, it is necessary to control spatially and temporally the cavitation activity, by discriminating the stable from the inertial regime. Firstly, the theoretical study of the dynamics of a monodisperse and homogeneous cloud shows a modification of the stable cavitation threshold as a function of the bubble density: the subharmonics emission threshold is lowered and the resonance frequency is shifted. The study leads also to the expression of a particular microbubbles density leading to optimized subharmonics emission. Secondly, a real-time control strategy based on a feedback loop process on subharmonics emission is designed. The use of this strategy allows discriminating the two cavitation states during time, and ensures a better reproducibility, time-stability and an acoustic energy gain. The control device is used for cells sonoporation in-vitro. In a first study, the sonoporation by inertial cavitation control is performed in a stationary ultrasonic field configuration. This leads to high sonoporation efficiency coupled to the possibility of counterbalancing the use of supplementary nuclei (encapsulated microbubbles). In a second one, the stable cavitation control applied in a focused ultrasound configuration field pinpoints the possibility of sonoporating cells without inertial cavitation, and then to limit cell lysis