Naol Negassa

Date of Award


First Advisor

Michael Bergman

Second Advisor

Aaron Williams


The aim of my thesis is to investigate the instability in particle levitation through an apparatus I built. I wanted to look into trying to understand the behavior of the stability of the particle levitation. This is currently something that I believe, if properly understood, could prove to be a large step forward in innovative technology. To answer this question, I began by performing a literature review on some papers that involved different applications of acoustophoresis, while focusing more on what particular focus in the field they were observing. Then, by working on my own apparatus, I began to conduct my own investigation on the stability of the levitation. I worked on one model of an acoustic setup that created an acoustic trap, holding a particle in suspension.
After creating the setup, I conducted a small analysis on the stability of suspension by recording the suspension. I used tracking software to keep a record of the vibrations of the particle as it levitated, for every frame of the video. Looking at the results, I observed that the vibrations could be classified into either more chaotic regimes or as constant oscillations. When the vibrations became unstable past a certain point, the movement was more violent and less predictable.
While conducting the analysis, I worked on providing some possible hypotheses for the reason these varying regimes in the levitation occur. I gave some possible suggestions and insights for what could be adjusted, such as implementations to the apparatus that I strongly believe would provide a more stable levitation. Considering the fact that the majority of research in this field is in the applications of acoustophoresis given our current ability, my work would hopefully inch our current capabilities forward by looking at one of the roadblocks more carefully. I would like to think that I would be able to provide a little more insight into what would potentially cause instability, even if it is just in certain conditions. As a consequence, this could be used as a reference for future implementations or as a starting point for a more thorough investigation on levitation stability.

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