Design and experimental test of a pulse oximeter system to acquire vital parameters.

Photoplethysmography is spectrophotometric technique used to calculate vital parameters. It is a promising technology due to its simplicity, low cost, and noninvasiveness and it has the potential for early screening for various atherosclerotic and cardiac pathologies. Although this technology has been used in pulse oximetry for the past 40 years, much research and innovation are still related to this topic. This is due to the recent widespread use of wearable devices that constantly monitor vital parameters. Particularly in the last two years, the use of these devices has increased significantly, especially for home applications, due to the Covid-19 pandemic. It is because of the growing interest in learning more about this technology and acquiring more knowledge about the world of biomedical instrumentation, which involves an inevitable combination of electronics and biomedicine, that this thesis project was born. It aims to develop a transmittance pulse oximetry device for calculating vital parameters such as pulse rate, arterial oxygen saturation, and pulse rate variability. Both the design part of the electronic circuit and the management and implementation of software algorithms to control the switching on off the LEDs and calculate the vital parameters are completely developed ex-Novo. The management of the circuit is handled via the Arduino Due board. A PCB was created for the designed circuit to facilitate the use of the device and reduce signal noise. Since it is often heard about telemedicine nowadays and how technology has made significant progress in this area, the idea arose to develop a web application that could be shared with the end-user (medical personnel) to allow real-time patient monitoring. The advantage of this option is that it facilitates the work of the doctor (e.g., in the case of a patient with covid) and of patients who perhaps have limited travel possibilities. Finally, an experimental analysis is carried out, collecting data from twelve subjects (eight males and four females) and comparing them with a commercial pulse oximeter used as a reference. In addition to the analysis of measurement error, it is also shown how important health indices can be derived from a PPG signal, such as the relationship between large artery stiffness and age.