Multifunctional Photoplethysmography Sensor Design for Respiratory and Cardiovascular Diagnosis

Photoplethysmography (PPG) is a transcutaneous optical signal acquisition method to monitor blood volume variations to assess cardiovascular health. Using a light source and a photodetector, PPG signals can be acquired and used in a vast application area. For the estimation of vital parameters like respiratory and heart rate, different properties of this pulsatile wave need to be further analyzed. This demands the utilization of different sensor techniques to be used like motion sensors, skin temperature monitoring and different wavelengths of light sources. This paper represents the proposed multipurpose PPG sensor design, called SmartPPG, which is able to measure multi-wavelength PPG from different skin penetration depths as well as skin temperature while providing motion tracking via an accelerometer. The manufactured prototype was tested for different PPG techniques to evaluate its applicability for arterial, venous and respiratory diagnosis.