Wearable PPG Sensor Matrix for Cardiovascular Assessment

Wearable biomonitoring systems and smart textiles for healthcare are gaining more importance and significance in the R&D sphere due to their potentials in healthcare and sports. Such biomonitoring systems offer a number of advantages in comparison to the conventional equipment proving mobility of the wearer during a long-term monitoring of vital parameters. There are different options to set up the physiological monitoring using wireless and wearable technologies. One of the scenarios is addressing textiles as a carrier of electronics. Moreover, those differ by their functional applications, registered physiological parameters and technology solutions. Still, the most demanded biomonitoring smart systems focus on the examination of cardiovascular conditions due to the urgency of the problem in the public health. Furthermore, cardiovascular and haemodynamic parameters are initial physiologic criteria in sports physiology and in individual training. The common method for cardiovascular assessment is registration of heart electric potentials. Nevertheless, this research addresses photoplethmography (PPG) as an optional approach to acquire the information on cardiovascular and hemodynamic activity. The aim of the study is to develop a textile integrated optical sensor matrix for telemetric cardiovascular assessment. Two reflectance sensors with single and multiple photodiodes (PDs) based on a novel signal conversion were designed and adopted to textiles. Designed prototypes were evaluated for their technical parameters and biomonitoring performance in rest conditions. The acquired physiological data was analyzed by the custom developed software and compared to the reference data obtained by the medical ECG monitor. Overall, the textile adopted wearable systems with both types of PPG sensors have demonstrated high signal accuracy and potentials for wearable applications.