Development of a reflective PPG signal sensor

PPG signal which reflects the changes of blood volume in the microvascular bed plays an important role in the cardiovascular disease diagnosis. It possesses high value to acquire the PPG signal accurately. Because the available measurement site of transmission mode PPG sensor is very limited, this paper presents a reflective PPG signal sensor which consists of a photodiode and four light sources surrounding the photodiode. The Monte Carlo simulation was performed to decide the distance between the light source and photodiode. To test the efficacy of the developed sensor, PPG signals were captured from five different measurement sites. The experiment results reveal that the proposed PPG signal sensor could acquire high quality PPG signals.