Browsing by Subject "Biomedical"
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Item Admittance measurement for assessment of cardiac hemodynamics in clinical and research applications(2012-05) Larson, Erik Rist; Pearce, John A., 1946-The admittance method is an important tool for the indirect determination of cardiac hemodynamics in animal research and has clinical potential as a hemodynamic monitor for implantable cardioverter-defibrillators (ICDs). Animal studies use a conductance catheter to determine left-ventricular (LV) volume, but ICDs must make use of existing pacing leads to perform an admittance measurement. This work aims to further the use of the admittance method by extending its use to multi-segment conductance catheters, determining parasitic circuit element's effects on electric property measurements, using biventricular pacing leads to determine cardiac hemodynamics, and analysis of spatial sensitivity using finite element models in various configurations. Experimental results show the admittance method can be used to determine LV stroke volume with biventricular pacing leads. Modeling results show removal of the muscle component focuses the measurement's spatial sensitivity towards the left-ventricular blood pool.Item Experimentally characterized embedded Mckibben muscle as a nastic material for biomedical applications(2009-06-02) Ewumi, Omotayo F.This study presents the experimental results that characterize a nastic sheet material?s performance. We defined nastic sheet as a McKibben muscle designed from a foundation that would be embedded as an array in an elastomer matrix. The goal is to be able to utilize the embedded McKibben sheets in the biomedical industry as an improvement to the synthetic devices and/or processes. One mechanism that might produce these improvements is to mimic the biological materials that form functional organs, biological structures, and active tissues. Linking human technology and natural structures is and will continue to be important to society for several reasons. It would improve: (1) the lifestyle of humans in regards to artificial parts that mimic human parts (which will allow us to live longer), (2) artificial limb functionality, and (3) comfort and aesthetics. The objective is focused on characterizing and evaluating McKibben muscles as an embedded muscle sheet by building McKibben muscles and testing them alone and in sheets with one, two, three, and five muscles. The sheets would be known as a single, double, triple and quintuple embedded sheet. Another objective is to determine the performance penalty that embedding puts on the material. The experiments performed used several different approaches, such as analytical models, tensile test analysis, and prototype construction of the specimens. All specimens were designed to have a constant final length of 120mm, being embedded in a polyurethane matrix. We characterized the fundamental performance of a McKibben muscle and each specific embedded sheet. We measured the specimens? work-density and quantified the inactive matrix?s impact on work-density. Based on the results, several improvements were suggested on the fabrication of the specimens. The experiment shows positive potential outcome that could be utilized in the biomedical field, but the results would improve with the suggestions provided in the study. A sample of the results - the actual work-density for both the single and doubleembedded sheets showed an increase to 7.82% and 2.96% consecutively. Once the specimens are removed from the mold, the McKibben muscle automatically tries to retract to its initial state while the polyurethane matrix tries to stay at its initial state.Item Redesign of the total wrist prosthesis to address wrist rotation(2013-05) Mehta, Jay Ravi; Crawford, Richard H.The human wrist is a vital joint in daily life, and it is subject to injuries and disease. Currently, severe wrist disease is normally treated with wrist arthrodesis, which is normally reliable but results in a fixed wrist incapable of allowing wrist motion. Another method of treating a nonfunctional or severely painful wrist is wrist arthroplasty where the wrist joint is replaced with an implant that allows wrist movement. As of yet, a suitable wrist implant has not been developed, especially for the case of the post-traumatic, young male wrist, and most current wrist implants fail from failure of the bone-implant interface. Through simulation and literature review, it is concluded that implants that restrict axial rotation are bound to fail overtime. With this conclusion, a new wrist implant prototype is designed that incorporates state of the art materials, fluid film lubrication, proper kinematics, a suitable range of motion, and more. This implant contributes several improvements to the field of wrist arthroplasty.