Next-Generation Raman tomography Instrument for Non-Invasive In Vivo Bone Imaging

Combining diffuse optical tomography methods with Raman spectroscopy of tissue provides the ability for in vivo measurements of chemical and molecular characteristics, which have the potential for being useful in diagnostic imaging. In this study a system for Raman tomography was developed and tested. A third generation microCT coupled system was developed to combine 10 detection fibers and 5 excitation fibers with laser line filtering and a Cytop reference signal. Phantom measurements of hydroxyapatite concentrations from 50 to 300 mg/ml had a linear response. Fiber placement and experiment design was optimized using cadaver animals with live animal measurements acquired to validate the systems capabilities. Promising results from the initial animal experiments presented here, pave the way for a study of longitudinal measurements during fracture healing and the scaling of the Raman tomography system towards human measurements

Robust spectroscopic quantification in turbid media

This thesis explores four methods for improving quantitative diffuse reflectance spectroscopy in light scattering media. In the introduction theories of light propagation in scattering media, relevant instrumentation for measuring light scattering properties, spectral data processing methods, and spectroscopically active bioanalytes are outlined. Next, two novel instruments for practical scattering measurements, and two novel data processing techniques are presented. Finally, directions for future research into diffuse reflectance spectroscopy are suggested. A novel photon time-of-flight instrument is used to measure scattering coefficients in tandem with a portable diode spectrometer. Measured scattering coefficients are used to correct co-measured near infrared spectra for scattering and for improving quantification. Reduced scattering coefficients were measured with coefficients of variation of 11.6% at 850 nm and 14.1% at 905 nm. This allows practical correction of light scattering in point-spectra. Using scattering-correction, estimates of dye concentration were improved by 35%. A novel device imaging annular patterns is presented. This imaging instrument is used to measure reduced scattering coefficients and absorption coefficients. Reduced scattering coefficients were measured with a coefficient of variation of 12.6%, and absorption coefficients were measured with a coefficient of variation 50% lower than using traditional imaging methods. A novel method for using parsimony in the development of data processing methods using genetic algorithms is presented. Genetic algorithms have been used to identify spectroscopic data processing methods for complex samples. ACette thèse explore quatre méthodes pour l'amélioration de la spectroscopie de réflectance diffuse quantitative dans des milieux qui diffusent la lumière. En introduction, une description des théories de la propagation de la lumière dans des médias qui diffusent celle-ci, des instruments pour mesurer les propriétés de diffusion, des méthodes de traitement des données spectrales, et des bioanalytes avec activité optique est donné. Un nouvel appareil à «temps de vol de photon» est présenté. Cet instrument portatif est utilisé pour mesurer le coefficient de dispersion en tandem avec un spectromètre à diode portable. Les coefficients de diffusion mesurés sont ensuite utilisés pour corriger la dispersion dans les spectres infrarouges co-mesurée, ainsi que l'amélioration de la quantification. Les coefficients de dispersion ont été mesurés avec une variation de 11,6% à 850 nm et 14,1% à 905 nm. En prenant en compte la dispersion, les estimations de la concentration de teinture ont été améliorées de 35%. Un nouvel appareil utilisant les modes d'imagerie annulaire pour mesurer les coefficients de dispersion et d'absorption est présenté. Les coefficients de dispersion ont été mesurés avec un coefficient de variation de 12,6%, et les coefficients d'absorption ont été mesurés avec un coefficient de variation amélioré de 50% par rapport aux méthodes d'imagerie traditionnelle. Une nouvelle méthode pour améliorer l'utilisation des mesures de simplicité dans le développement de méthodes de traitement des données via des algorithmes génétiques est présentée. Les algorithmes génétiques ont été utilisés pour identifier les mé

Microstress in Reactionâ Bonded SiC from Crystallization Expansion of Silicon

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134484/1/jace14398_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134484/2/jace14398.pd

Using Raman spectroscopy to characterize biological materials

Raman spectroscopy can be used to measure the chemical composition of a sample, which can in turn be used to extract biological information. Many materials have characteristic Raman spectra, which means that Raman spectroscopy has proven to be an effective analytical approach in geology, semiconductor, materials and polymer science fields. The application of Raman spectroscopy and microscopy within biology is rapidly increasing because it can provide chemical and compositional information, but it does not typically suffer from interference from water molecules. Analysis does not conventionally require extensive sample preparation; biochemical and structural information can usually be obtained without labeling. In this protocol, we aim to standardize and bring together multiple experimental approaches from key leaders in the field for obtaining Raman spectra using a microspectrometer. As examples of the range of biological samples that can be analyzed, we provide instructions for acquiring Raman spectra, maps and images for fresh plant tissue, formalin-fixed and fresh frozen mammalian tissue, fixed cells and biofluids. We explore a robust approach for sample preparation, instrumentation, acquisition parameters and data processing. By using this approach, we expect that a typical Raman experiment can be performed by a nonspecialist user to generate high-quality data for biological materials analysis