Theses and Dissertations at Montana State University (MSU)
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/733
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Item Resistance temperature devices fabricated using micro electromechanical systems technology designed and characterized for low-temperature applications(Montana State University - Bozeman, College of Engineering, 2020) Thomae, Madelyn Ruth; Chairperson, Graduate Committee: Stephan WarnatResearch shows that microorganisms play a major role in climate change, but there is a lack of adequate understanding of microbial involvement in climate change and further research is needed for greater understanding. Temperature monitoring lends an insight into the current climatic shifts in Arctic and Antarctic regions. Currently, satellite monitoring is used to track temperature changes in those regions. To further the understanding of the role microorganisms play in the rising temperatures in those regions, in-situ temperature monitoring is needed. Commercially available temperature probes are high in cost and not well-suited for the harsh environment of Arctic and Antarctic regions. Utilizing micro electromechanical systems technology provides a solution for robust low-cost, low-power sensors that can be designed specifically to operate in harsh environments. Gold resistance temperature devices were designed and fabricated using micro electromechanical systems technology with a high spatial resolution capable of detecting microorganisms in subzero applications. The fabricated temperature sensors were calibrated for subzero use and freezing experiments were done to detect any changes due to impurities in the sample. The gold resistance temperature devices were able to withstand prolonged exposure to the harsh experimental environment and provide an accurate spatial temperature gradient throughout the media. The gold resistance temperature devices had negligible effects due to the self-heating phenomenon common in resistance temperature devices. Additionally, the sensors were able to detect variations in the freezing curve of the media with the inclusion of the bacterial isolate Flavobacterium sp. ANT 11 (accession number GU592435) in DI water samples. Future research should focus on (1) furthering the understanding of the microbial interactions in the cooling curves of different medias and (2) integrating electrical impedance spectroscopy sensors to provide knowledge of what impurities are in the sample that could be affecting the freezing curve of the media.Item Dynamic response of mini cantilever beams in viscous media(Montana State University - Bozeman, College of Engineering, 2010) Mishty, Anamika Sharmin; Chairperson, Graduate Committee: Ahsan MianIn concurrent engineering, viscosity and density of a fluid are two important parameters as they are the indicators of some predefined standards of the concerned fluids in some specified application. Arguably fluids play an important role in all major engineering applications starting from automobile to biofilm. In this work, we will demonstrate the use of mini cantilever beams for characterization of rheological properties of viscous materials such as lubricating oils. Further miniaturization of the test platform can lead to a MEMS device that can potentially be used for measuring the rheological properties of soft viscoelastic materials such as biofilm. Miniaturization of the measuring instrument is necessary so a small sample volume can be used to perform the test. In this study, the dynamic response of cantilever beams was measured experimentally in air and viscous fluids (e.g. water, and lube oils of three different grades) using a duel channel PolyTec scanning vibrometer. The changes in dynamic response of the beam such as resonant frequency, frequency amplitude, and the Q-factor were compared as functions of the rheological properties (density and viscosity) of fluid media. It may be mentioned here that we used two cantilever beam configurations, one was the plain small stainless steel beam and another was a small stainless steel beam with an aluminum mass attached to it. For both the configurations, the samples were excited by an external shaker at sweeping frequency modes and the beams' motions were recorded by the laser vibrometer focused at different locations of a beam's surface. The reflected signal is directed to a split photo detector whose output is sent to fast-Fourier Transform [FFT] spectrum analyzer.