Date of Award

Summer 8-2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Mechanical & Aerospace Engineering

Program/Concentration

Mechanical Engineering

Committee Director

Julie Z. Hao

Committee Member

Venkat Maruthamuthu

Committee Member

Orlando Ayala

Committee Member

Krishnanand Kaipa

Abstract

Cardiovascular diseases (CVDs) are the leading cause of morbidity and premature death worldwide. The arterial pulse waveform (APW) is a vital diagnostic tool for assessing cardiovascular health and detecting vascular pathology, yet diagnostic accuracy is highly susceptible to numerous factors that affect the fidelity of non-invasive pulse measurements. Over the years, research on the impact of these factors has also faced challenges in quantifying the results. Therefore, to overcome these limitations, a comprehensive understanding is crucial for accurately interpreting APW data in clinical diagnostics. Given the unreliability of arterial pulse measurements, a coupled string-SDOF framework is developed to study how pulse measurement affects the true and measured pulse signals in an artery.

In this dissertation, the analytical framework was developed based on two distinct physiological cases: a baseline uniform-artery model and a realistic tapered-artery model. In both cases, the artery is modeled as a vibrating string, with the string's displacement representing the arterial wall's displacement. A tissue-contact sensor (TCS) stack, consisting of overlying tissue and a sensor, transmitted the true arterial pulse signal to the sensor as a measured pulse signal, and the stack was modeled as a single-degree-of-freedom (SDOF) system. As a local disturbance, this SDOF system interacted with the vibrating string, yielding a coupled string-SDOF model.

The related numerical calculations were conducted in MATLAB, across diverse sensing modalities: tactile sensors, accelerometers, photoplethysmography (PPG) sensors, and ultrasound. The analytical models revealed that the interaction introduces localized mechanical loading, altering key hemodynamic parameters and causing frequency-dependent harmonic distortion in the arterial pulse waveform (APW). The tapered model further demonstrated that arterial tapering amplifies wave reflection and alters local compliance, making tapered segments more sensitive to sensor-induced distortion than uniform segments.

Thus, this coupled string-SDOF model provides a foundational mathematical framework for quantifying artery-sensor interactions in the future. Ultimately, this work is crucial in compensating for measurement effects and accurately reconstructing the uncorrupted arterial pulse signal, thereby enhancing the clinical utility of APW analysis.

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DOI

10.25777/y5jy-2085

ISBN

9798193214496

ORCID

0009-0008-2229-1183

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Available for download on Tuesday, October 05, 2027

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