Cardiovascular disease and sleep apnoea: A wearable device for PPG acquisition and research aims

Many scientific research try to relate PPG signals to other physiological parameters, such as breathing rate, blood pressure, blood vessel elasticity, blood viscosity and other cardiovascular compliances and diseases. The aim of this work is to develop a platform composed of a wearable device and a digital framework for continuous acquisition and processing of photoplethysmography (PPG) signals for scientific researches on cardiovascular disease (CVD) and sleep apnoea (SA). We developed a MATLAB-based framework for off-line algorithm research and a battery powered microcontroller-based, bluetooth enabled, wearable device for PPG signal acquisition. The first problem we had to face was the type of PPG sensor to use. The best solution we found was the new Nellcor SpO2 forehead reflectance sensor, called Max-Fast. Moreover, we improved the Max-Fast sensor with a MEMS three-axis accelerometer for motion artefacts detection. Thanks to the wireless communication link to a PC, the wearable device can be used in different scenarios such as clinical environments, dangerous situations, sport activity, during sleep, and also at home in telemedicine systems. At the same time, the digital signal processing framework allows new algorithms research on automatic analysis of PPG signals in the field of CVD and SA.