Effect of sensor configurations on indirect-contact photoplethysmogram measurement system

Indirect-contact photoplethysmography is a new approach to measure photoplethysmogrm over clothing for unconstrained and unconscious monitoring purpose. In this paper, the effect of sensor configurations on indirect-contact photoplehysmography was investigated. Sensor configuration was classified into two groups. One was multiple light sources with centered photo-detector configuration and the other was multiple photo-detectors with centered light source configuration. Total 8 kinds of sensors were tested. Experimental results showed that although both sensor groups have possibility to photoplethysmogram measurement over clothing, sensors with multiple light sources showed better performance when thick clothes were considered. Sensor configuration should be selected with regard to its application considerations such as power consumption or target subjects.