Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 33 for “"Micropillar"”.
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Capillary Force in High Aspect-Ratio Micropillar Arrays
High aspect-ratio (HAR) micropillar arrays are important for many applications including, mechanical sensors and actuators, tunable wetting surfaces and substrates for living cell studies. However, due to their mechanical compliance and large surface area, the micropillars are susceptible to …
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Comprehensive modeling of thin film evaporation in micropillar wicks
In the Information Age, society has become accustomed to continuous, rapid advances in electronics technology. As the power density of these devices increases, heat dissipation threatens to become the limiting factor for growth in the electronics industry. In order to sustain rapid growth, the …
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Biomimetic cytoskeleton assemblies and living cells on micropillar force sensor arrays
Micropillar force sensor arrays are produced for biophysical studies of cellular and intracellular mechanics and for the assembly of suspended biofilament networks. Three types of pillars are made: (1) gold capped silicon pillars, (2) epoxy pillars and (3) polydimethylsiloxane (PDMS) pillars. …
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Coherently-driven exciton polaritons and directional cQED effects in the quantum dot-micropillar system
… spatially-resolved studies of the QD-micropillar system in the both weak and strong coupling regime. For this purpose an advanced 90 degree excitation and detection scheme, suitable for efficient wavelength-independent driving of the coupled exciton (X) and cavity mode (C) system, was …
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Thin-film evaporation from well-defined silicon micropillar wicks for high-heat-flux thermal management
… capillary pumped thin-film evaporation from micropillar wicks has received significant attention owing to advances in micro/nano-fabrication and the potential to dissipate high heat fluxes by increasing the evaporative area. Yet, predictive tools to design various wicking structures are not …
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Modeling Droplet Impingement Dynamics on Micropillar-Arrayed Viscoelastic Substrates Through Microgeometry-Free and Multiscale Methods
The droplet impact dynamics on micropillar-arrayed viscoelastic substrates has been thoroughly investigated by two distinct modeling methods, i.e., microgeometry-free and multiscale modeling methods. The viscoelasticity of the micropillar-arrayed substrate is characterized by a five-parameter …
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Enhanced Heat Transfer Performance by Shape Optimization of a Non-axisymmetric Droplet Evaporating on a Heated Micropillar
… Non-axisymmetric Droplet Evaporating on a Heated Micropillar</p> <p>By</p> <p>Haotian Wu</p> <p>Department of Mechanical Engineering and Materials Science</p> <p>Washington University in St. Louis, 2019</p> <p>Research Advisor: Professor Damena Agonafer</p> <p>The stacked multilayer 3D IC …
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Bubble dynamics on structured surface in microchannel
… unclear. In this thesis, bubble dynamics on micropillar array surfaces were studied. A surface energy based model is presented to predict the bubble morphology on pillar array surfaces. The results showed that bubbles tend to stay on top surfaces of pillars at solid fractions greater than …
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Enhanced flow boiling heat transfer in microchannels with structured surfaces at varied mass flow rates
… heat transfer in microchannels with surface micropillar arrays. The motivation for this investigation was to determine the general trends of the optimal micropillar array geometry in terms of its heat transfer capabilities. The experiment was conducted with three microchannels: a flat surface …
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Evaporation-induced non-wetting droplets on superhydrophilic surfaces
… were used to fabricate well-defined silicon micropillar arrays with a square pattern with varying pillar diameter, height, and center-to-center spacing. Water droplets placed on these microstructured surfaces at room temperature demonstrated superhydrophilic behavior with liquid filling the …
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Micro and nanostructures for two-phase fluid and thermal transport
… numerical model for thin-film evaporation from micropillar array wick structures. The model can predict the dry-out heat flux on various micropillar structure geometries (diameter, pitch, and height) in the length scale range of 1-100 pm and capture the optimal geometries to maximize the dry-out …
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Surface structure enhanced microchannel flow boiling of low surface tension fluids
… wall of silicon test samples, with/without micropillars of two different heights (25 and 75 µm) and two different cylindrical pillar solid fractions (~ 5% and 20%). For methanol, a maximum CHF of 494 W/cm^2 was achieved with a structured surface, a 61% enhancement compared to smooth surface. …
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Coherent Interaction Between Laser Photons and Single Spins in InAs Quantum Dots
… InAs/GaAs quantum dots embedded in semiconductor micropillar cavities. In the first experiment, it is shown that a quantum dot spin can be used as a non-linearity to induce a photon phase shift. This is extended using spin-pumping techniques to create a single-photon phase switch, which is an …
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Deformation Localization in Constrained Layers of Metallic Glasses: A Parametric Modeling Analysis
… for experimental ob- servations based on the micropillar compression test. The deformation pattern in a multilayered metallic glass structure as well as the deformation pattern in a metallic glas beam subjected to four point bending are also examined.
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CELL GEOMETRIC CONSTRAINTS REGULATE NUCLEAR AND CHROMATIN PLASTICITY VIA ACTOMYOSIN CONTRACTILITY
… not well understood. In the first project, using micropillar substrates and correlation analysis techniques, we measured the time scale at which nuclear and chromatin dynamics respond to traction forces at cell periphery in unperturbed cells. In the second project, using nuclear envelope …
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Stick-slip behavior of liquid droplets on pillar-arrayed PDMS surfaces
… force over time when moving droplets over micropillar pattened surfaces. MATLAB programs were developed to analyze both force and image data. Four parameters are found to have strong correlation with a droplet’s stick-slip behavior: pillar array spacing, droplet moving velocity, liquid …
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Spatial Dynamics and the Mechanoresponse in CD4+ T Cell Activation
… forces is then investigated through use of micropillar arrays. This approach also enables the quantification of forces generated by T cells during cellular activation. The impact of CD28 costimulation on TCR-driven force generation is assessed and noted to increase cellular forces by 80% …
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Wetting and phase-change phenomena on micro/nanostructures for enhanced heat transfer
… resistance to predict the propagation rates in micropillar arrays with high aspect ratios. Our experimental results showed good agreement with the model, and design guidelines for optimal propagation rates were proposed. For micropillar arrays with low aspect ratio and large spacing between …
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High-throughput platforms for investigating bioadhesion and cell migration
… main focus of this thesis used a fabricated, micropillar based wound healing platform to conduct high throughput wound healing analyses. With this approach, I investigated the impact of genetic variations on endothelial wound healing relevant to acute lung injury.
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Droplet-based Two-phase Thermal Management
… by the bottom substrate and the side wall of the micropillar through numerical simulations and experimental investigation. We find that raising the micropillar height from 0 to 2R, 5R, and 20R led to 26%, 35%, and 42% enhancements, respectively, in the total evaporation rates of a hemispherical …
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