Available at: https://digitalcommons.calpoly.edu/theses/2826
Date of Award
6-2024
Degree Name
MS in Biomedical Engineering
Department/Program
Biomedical Engineering
College
College of Engineering
Advisor
Michael D Whitt
Advisor Department
Biomedical Engineering
Advisor College
College of Engineering
Abstract
The purpose of this study is to develop a test method to non-invasively measure the development of subclinical atherosclerosis through acoustic sound wave analysis. This test method involves the manufacturing and use of silicone arteries with varying relative roughness values in their inner diameters to mimic arterial plaque buildup, a flow model, and a physiological microphone. A flow model that can generate both steady and oscillatory flow to mimic the pulsatile flow of a heartbeat was developed to successfully test and analyze fluid flow through the varying arteries. The first finding in this study was that confocal microscopy is an effective method is quantifying the surface roughness of the inner diameter the silicone artery phantoms. Results of this study found that the surface roughness of the arteries reflects the increase of surface roughness hypothesized when manufacturing the artery molds. The gravitational flow model experimental design proved to be effective in collecting steady flow data that was used to verify the experimental relative roughness and friction factor values. Additionally, the results indicated that pressure drop and friction factor (both experimental and theoretical) increased as the surface roughness of the artery increased. Furthermore, the pulsatile flow model was unsuccessful in generating a consistent frequency that was greater than 2.0 Hz. Because of this, many of the Womersley’s numbers remained undefined or frequency dependent. No concrete conclusions can be drawn regarding the relationship between Womersley’s number and surface roughness during pulsatile flow. A key finding in this study was that the signal power of an FFT of the audio data vs. relative roughness for both steady and pulsatile flow conditions experienced a slightly positive linear association. Meaning that there could be a relationship between the increase of surface roughness and the increase of signal power in an FFT of the audio data. Based on the findings in this study, this demonstrates that there could be a method to correlate the values of signal power to a specific relative roughness value.