Keywords

Seismocardiography (SCG); Portable respiratory monitoring; Biomedical signal processing; Phase delay; Spirometry; Cross-correlation analysis

Abstract

Seismocardiography (SCG) and respiratory signals are intricately linked, and accurate synchronization is crucial for understanding cardiopulmonary interactions. However, respiratory measurement techniques can introduce timing errors, resulting in phase delays that may affect signal interpretation. This study aims to characterize these timing differences and establish a methodology for evaluating phase delays between respiratory monitoring modalities. Benchmark pilot testing was first conducted using a shaker system as an idealized model of controlled chest wall movement to characterize the temporal relationship between an accelerometer, laser Doppler vibrometer, and linear displacement sensor. The laser Doppler vibrometer served as a gold standard reference due to its manufacturer-specified timing delay. Cross-correlation analysis was used to quantify time delays and phase differences between signals, demonstrating that both time and phase delays generally increased as excitation frequency decreased. Preliminary testing was then conducted using a ventilator as a potential idealized respiratory system to simulate chest wall movement while providing airflow measurements. Two sets of trials were performed by varying respiratory rate (frequency) and tidal volume. Similar to the shaker pilot testing, decreasing respiratory rate resulted in increased time and phase delays. However, varying tidal volume while maintaining a constant respiratory rate produced no notable differences in time or phase delay, suggesting that tidal volume is not a significant contributor to timing differences between measurement modalities. Finally, a multimodal human testing methodology was proposed to evaluate phase delay relationships under physiological conditions using a spirometer, respiratory belt, SCG, ECG, GSR, accelerometer, and laser Doppler vibrometer. This work provides insight into timing limitations between respiratory measurement techniques and establishes a foundation for future evaluation of portable respiratory monitoring systems.

Thesis Completion Year

2026

Thesis Completion Semester

Summer

Thesis Chair

Mansy, Hansen

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Thesis Discipline

Mechanical Engineering

Language

English

Access Status

Open Access

Length of Campus Access

None

Campus Location

Orlando (Main) Campus

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Available for download on Friday, July 30, 2027

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Rights Statement

In Copyright