Investigating advanced applications with photoplethysmography waveforms and sensor design.

• Main Author: Wong, Mark Kei Fong.
• Other Authors: Lee Kijoon
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Engineering::Bioengineering
• Online Access: http://hdl.handle.net/10356/50016
• Institution: Nanyang Technological University

The project consists of three major topics being studied. In the first objective, the usefulness and limitations of pulse oximetry and PPG, its implementation and operation principles are discussed. The promising potential beyond that of simple heart-rate (HR) and blood oxygenation (SpO2) measurements can be extracted with simple software and hardware modifications to a now-medically standard clinical tool is highlighted. In the second part of this thesis describes the processes, considerations and work done in the prototyping of a wearable wrist-mounted pulse oximeter using commercially available electronic components and EAGLE CAD and LabVIEW software. The benefits of reflectance mode pulse oximetry are argued to offer a smaller and more superior solution for integration into a wearable bio-monitoring sensor. The objectives and motivation described in detail in the report. The third section of this report explores in-depth experimental analysis of the PPG waveform both of the literature and experimentally. PPG signals of 14 healthy subjects were measured at four extremities at normal and forced respiratory states, the nature of the measured PPG signals are then related to the various states of the cardiovascular system. Signal processing algorithms and artifact reduction methodologies were studied. We are able to demonstrate that with further processing in MATLAB, further signals can be interpreted from the ubiquitous waveform such as HR, SpO2, respiration, pulse transit time (PTT), pulse wave velocity (PWV) and even fat content; these signals were then correlated to actual physiological parameters of the given subject.Results from the discoveries made conclude that robust PPG signals can be reliably obtained at the wrist, PTT, respiration and Valsalva effects on the waveform have been found to concur with current literature.