Ce travail présente le développement de spectromètres photoacoustiques pour la mesure de traces de gaz avec des résonateurs de Helmholtz différentiels.La cuve représente le coeur de l'instrument, le laser qui la traverse va créer une onde de pression stationnaire qui sera mesurée par des microphones. Le signal photoacoustique est fonction de la concentration du gaz et la manière dont il sera amplifié va dépendre en grande partie de la géométrie de la cuve. Une méthode aux éléments finis est utilisée pour exprimer cette caractéristique selon les modes et les fréquences propres calculées de la cuve. Les paramètres clés de la cuve sont ainsi calculés, comme la fréquence de résonance, le facteur de qualité et la constante de la cuve. Contrairement à d'autres méthodes de spectroscopie infrarouge, la sensibilité des spectromètres photoacoustiques augmente alors que la cuve se miniaturise. Cette particularité est vérifiée expérimentalement avec un bon accord avec la simulation. La modélisation prouve une nouvelle fois être suffisamment robuste pour être utilisée dans un processus d'ingénierie du spectromètre. Cet outil va en effet permettre d'optimiser les dimensions du résonateur selon les besoins de l'application, soit en privilégiant le maximum de signal, la plus haute fréquence de travail ou encore le plus faible encombrement. De nombreuses cuves ont été développés avec l'aide de la simulation, l'écart observé avec les paramètres expérimentaux est de l'ordre de 15 %. Enfin, les applications actuelles en mesure de traces de gaz demandent de mesurer la concentration d'au moins deux gaz, de façon simultanée, avec des niveaux de détection proche du ppb. Un mode de résonance de Helmholtz particulier est trouvé afin de proposer une mesure multi-gaz. Enfin, la sensibilité est augmentée grâce à un système multi-passages. / This work presents the conception of a photoacoustic spectrometer dedicated to trace gas measurements using a differential Helmholtz resonator. The main component of the instrument is the cell, where a standing wave is produced by a laser excitation and is measured with microphones. The photoacoustic signal is proportional to the gas concentration and the cell shape mainly affects its amplification. A finite element method is used to find this characteristic by calculating the cell eigenmodes and eigenfrequencies.Key parameters of the cell are then calculated, including cell frequency, quality factor and cell constant. Unlike other infrared spectroscopy methods, sensitivity of photoacoustic spectrometers increases by miniaturization process. This particular phenomenon is experimentally verified and is in good agreement with the simulation.Modelization proves again its robustness to be used on an engineering process of the spectrometer. This tool allows to optimize resonator dimensions according to the application, favouring maximum signal, higher working frequency or reduced size. Many cells designed with the help of the simulation are presented, where the observed error with experiments is of the order of 15 %. Finally, today's trace gas applications need the measurement of at least two concentrations, simultaneously with detection limits down to the ppb level. A novel Helmholtz resonance mode is then found to allow multi-gas sensing.Finally, sensitivity is increased by multi-pass systems.

We consider the inverse source problem arising in thermo-and photoacoustic tomography. It consists in reconstructing the initial pressure from the boundary measurements of the acoustic wave. Our goal is to extend versatile time reversal techniques to the case when the boundary of the domain is perfectly reflecting, effectively turning the domain into a reverberant cavity. Standard time reversal works only if the solution of the direct problem decays in time, which does not happen in the setup we consider. We thus propose a novel time reversal technique with a nonstandard boundary condition. The error induced by this time reversal technique satisfies the wave equation with a dissipative boundary condition and, therefore, decays in time. For larger measurement times, this method yields a close approximation; for smaller times, the first approximation can be iteratively refined, resulting in a convergent Neumann series for the approximation.

Photoacoustic (PA) Imaging is an emerging biomedical imaging modality based on the laser-generated ultrasound. The method has unique advantages in providing microvessel structure visualization, neuroimaging, and functional imaging provided by its physical principle. Photoacoustic microscopy (PAM) is one of the PA imaging instruments which provides high resolution and contrast imaging of a near-field target. Relying on the acoustic focusing, Acoustic-resolution PAM (AR-PAM) is capable of reaching a sub-centimeter of penetration depth with sub-millimeter resolution and is optimized for tissue samples and small animals. However, the state-of-art AR-PAMs are large in size and expensive in cost, which hinders its democratization. There are previous researches conducted on reducing the cost by introducing a low-cost optical source or ultrasound acquisition device. Few research has investigated the possibility of modification on actuator design. The total system cost should be further reduced by substituting the translation stage while maintaining the imaging quality. In this research, a delta configuration actuation is introduced to the AR-PAM. The delta-configuration actuation adapted from a low-cost off-the-shelf 3D printer has been implemented in the design. An economical PAM system that integrates the combination of hardware and software enhancement is designed and tested in this research. With the software approach, advanced beamforming methods such as Delay-and-Sum with Coherence Factor (DAS+CF) and Delay-Multiply-and-Sum (DMAS) algorithms are applied to obtaining the high-resolution PA image through 3D reconstruction. The preliminary phantom study demonstrated the applicability of low-cost delta configuration actuators for AR-PAM imaging. The simulation study shows the beamforming algorithms has capability to remove the device precision error and increasing the tolerance. The research suggests that the 3D reconstruction algorithms significantly improve the resolution and contrast of the image quality.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22328号 / 医博第4569号 / 新制||医||1041(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 大森 孝一, 教授 椛島 健治, 教授 松田 秀一 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22460号 / 工博第4721号 / 新制||工||1737(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 近藤 輝幸, 教授 大江 浩一, 教授 中村 正治 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23215号 / 工博第4859号 / 新制||工||1758(附属図書館) / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 大江 浩一, 教授 近藤 輝幸, 教授 深澤 愛子 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18979号 / 工博第4021号 / 新制||工||1619(附属図書館) / 31930 / 京都大学大学院工学研究科マイクロエンジニアリング専攻 / (主査)教授 鈴木 基史, 教授 木村 健二, 教授 蓮尾 昌裕 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21684号 / 医博第4490号 / 新制||医||1036(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 松田 道行, 教授 松田 秀一, 教授 椛島 健治 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

Small molecule organic dyes with absorption and emission in the near infrared region (NIR) attracted much attention for various applications such as dye sensitized solar cells, fluorescent guided surgery, stimuli responsive bioimaging and photodynamic therapy. Dyes with high absorption and emission in the NIR region are beneficial for stimuli responsive bioimaging due to the deeper penetration of NIR light, less cell damage, high resolution, and low background autofluorescence from biomolecules. Of the many small molecule dyes, xanthene-based dyes exhibit outstanding photophysical properties and good stimuli response for use in bioimaging applications. However, absorption and emission of the xanthene dyes lie in the visible region, which limit their applications in cellular imaging. Many of the NIR dyes have very poor fluorescence; consequently, an alternative approach to fluorescent imaging is photoacoustic imaging that uses sound waves to generate pictures of deep tissues. In this dissertation, we discuss the utility of xanthene based NIR dyes as photoacoustic imaging contrast agents for multiplex imaging and deep tissue nitric oxide sensing in the drug-induced liver injury. Chapter I discuss the fundamentals of fluorescence and photoacoustic imaging, background of the xanthene dyes and other fluorescent dyes, and the design strategies to develop NIR xanthene-based dyes. Chapter II is based on our approach to the design and synthesis of NIR xanthene-based dyes by C-H bond functionalization, with the first example being Rhodindolizine, which absorb and emits in NIR II or short-wave infrared (SWIR) region. In chapter III, we describe the design and synthesis of thienylpiperidine xanthene-based NIR and shortwave-infrared (SWIR) dyes for the photoacoustic imaging. One dye in particular (XanthCR-880) boasts a strong PA signal at 880 nm with good biological compatibility and photostability, yields multiplexed imaging with an aza-BODIPY reference dye, and is detected at a depth of 4 cm. In chapter IV, we report a series of SWIR dyes based on a dibenzazepine donor conjugated to thiophene (SCR-1, SCR-4), thienothiophene (SCR-2, SCR-5), and bithiophene (SCR-3, SCR-6). We leverage the fact that SCR-1 undergoes a bathochromic shift when aggregated to develop a ratiometric nanoparticle for nitric oxide (NO) (rNP-NO). rNP-NO was used to successfully perform in vivo studies to visualize pathological levels of nitric oxide in a drug-induced liver injury model via deep tissue SWIR photoacoustic (PA) imaging. Chapter V describes another series of xanthene-based dyes with a thiophene ᴫ spacer and several different donors. UV-Vis absorption studies were performed after converting the dyes to the opened form with trifluoracetic acid. These novel XanthCR-TD dyes exhibit absorption maxima in NIR I region from 700 - 900 nm.

Orientador: Antonio Manoel Mansanares / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin / Made available in DSpace on 2018-09-26T13:53:30Z (GMT). No. of bitstreams: 1 Mesquita_RicksonCoelho_M.pdf: 13672557 bytes, checksum: bbf3df05cb82c513d1c69aa2b28b84da (MD5) Previous issue date: 2005 / Resumo: O nível de iluminação das plantas é determinante da estrutura das folhas, em particular no tocante à quantidade e distribuição dos cloroplastos. O objetivo deste projeto é utilizar a técnica fotoacústica para demonstrar as diferenças fisiológicas entre plantas adaptadas a diferentes condições de irradiância. Plantas de tabaco foram cultivadas em dois níveis distintos de irradiância. Plantas congenéricas, provenientes de habitats diferentes (cerrado e mata atlântica), crescidas sob o mesmo nível de exposição à luz, também foram estudadas. Como a técnica fotoacústica é sensível ao O2 produzido na fotossíntese, a resposta dos sistemas fotossintéticos das plantas de diferentes condições foi avaliada por meio de medidas fotoacústicas de indução fotossintética. A quantidade de energia armazenada também foi determinada nessas plantas. A partir da contribuição da evolução de O2 para o sinal fotoacústico, obtivemos espectros de ação para as diferentes amostras. Os resultados mostraram que plantas adaptadas a ambientes de sol são menos eficientes em armazenar energia para as reações fotoquímicas. As curvas de indução indicaram que essas plantas demoram um tempo maior para atingir um estado estacionário de produção de O2. Experimentos de fotoinibição mostraram que plantas adaptadas a baixas irradiâncias são mais sensíveis ao excesso de luz saturante. Foi observada uma absorção de O2 após a saturação fotossintética em plantas de tabaco de sol, associada a uma provável competição entre fotossíntese e fotorrespiração. Os espectros de ação, obtidos pela primeira vez a partir de medidas fotoacústicas de produção de O2, mostraram uma boa concordância com a literatura (valores obtidos por outras técnicas) / Abstract: Ilumination level of plants during its growth is determinant for structure of leaves, specially refering to quantity and distribution of chloroplasts. The aim of this project is to use the photoacoustic technique to show physiological differences among plants adapted to different light intensity conditions. Tobacco plants were grown up under two distint irradiance levels. Congeneric plants, coming from different habitats (cerrado and florest), grown up under the same light level, were also studied. Since photoacoustic technique is sensitive to O2 produced by photosynthesis, photosynthetic response of plants from different light conditions were studied through PA measurements of photosynthetic induction. The energy storage was also determined in these plants. From the oxygen component of the photoacoustic signal it was possible to obtain action spectra for all the samples. Results showed that plants adapted to sunlight present lower efficiency in storing energy to photochemical reactions. The induction curves indicated these plants also take a longer time to reach a steady state of O2 production, after remaining a period in the dark. Photoinhibition experiments showed that plants grown up under lower light are more susceptible to excess of saturating light. It was also observed O2 uptake after photoinhibition in plants grown under full sunlight, which was associated to a competition between photosynthesis and photorespiration. The action spectra, obtained for the first time with photoacoustic measurements of O2 production, showed a good agreement with literature / Mestrado / Física da Matéria Condensada / Mestre em Física