Photonic sensor design evaluation for measuring the photoplethysmogram

Recently noninvasive cuffless and continuous measurement techniques of photoplethysmogram (PPG) signals get lots of attention in medical diagnosis for 24/7 monitoring. Moreover, the strive towards low cost, portability, simple construction and simple analysis techniques paves the way for mobile health care. Several research papers have been published on PPG sensors to extract the PPG signal which consider only one specific source, either a LED or a Laser diode. Besides, earlier work show limited work considering the size of the sensor with respect to distance between the light sources and the detector used. In this paper, we build a simple cuffless and wearable PPG sensor. Various parameters such as: source types, light's wavelength, source-sample and source-detector distances and sensor configuration (reflection and transmission) are considered. The combination of image processing and signal processing technology is used to extract the PPG signal out of the PPG sensor. Finally, the PPG sensor is validated by measuring the blood pressure and compared the result with an oscillometric device.