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Browsing by Subject "atomic force microscopy"
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Item AFM-Based Fabrication of Nanofluidic Device for Medical Application(Office of the Vice Chancellor for Research, 2014-04-11) Promyoo, Rapeepan; El-Mounayri, Hazim; Karingula, Varun KumarRecent developments in science and engineering have advanced the atomic manufacture of nanoscale structures, allowing for improved high-performance technologies. Among them, AFM-based nanomachining is considered a potential manufacturing tool for operations including machining, patterning, and assembling with in situ metrology and visualization. In this work, atomic force microscope (AFM) is employed in the fabrication of nanofluidic device for DNA stretching application. Nanofluidic channels with various depths and widths are fabricated using AFM indentation and scratching techniques. To introduce the fluid inside the nanochannels, microchannels are made on both sides of the nanochannels. Photolithography technique is used to fabricate microfluidic channels on silicon wafers. A 3D Molecular Dynamics (MD) model is used to guide the design and fabrication of nanodevices through nanoscratching. The correlation between the scratching conditions, including applied force, scratching depth, and distant between any two scratched grooves and the defect mechanism in the substrate/workpiece is investigated. The MD model allows proper process parameter identification resulting in more accurate nanochannel size.Item Multi-scale Analysis of Bone Chemistry, Morphology and Mechanics in the oim Model of Osteogenesis Imperfecta(2014-08) Bart, Zachary R.; Hammond, Max A.; Wallace, Joseph M.Osteogenesis imperfecta is a congenital disease commonly characterized by brittle bones and caused by mutations in the genes encoding Type I collagen, the single most abundant protein produced by the body. The oim model has a natural collagen mutation, converting its heterotrimeric structure (two α1 and one α2 chains) into α1 homotrimers. This mutation in collagen may impact formation of the mineral, creating a brittle bone phenotype in animals. Femurs from male wild type (WT) and homozygous (oim/oim) mice, all at 12 weeks of age, were assessed using assays at multiple length scales with minimal sample processing to ensure a near-physiological state. Atomic force microscopy (AFM) demonstrated detectable differences in the organization of collagen at the nanoscale that may partially contribute to alterations in material and structural behavior obtained through mechanical testing and reference point indentation (RPI). Changes in geometric and chemical structure obtained from µ-Computed Tomography and Raman spectroscopy indicate a smaller bone with reduced trabecular architecture and altered chemical composition. Decreased tissue material properties in oim/oim mice are likely driven by changes in collagen fibril structure, decreasing space available for mineral nucleation and growth, as supported by a reduction in mineral crystallinity. Multi-scale analyses of this nature offer much in assessing how molecular changes compound to create a degraded, brittle bone phenotype.