Research On Reduction Of Motion Artifact In PPG Signal

Photoplethysmography signal(PPG signal)is a kind of periodic waveform representing pulse variation and containing lots of blood vessel related physiological informations.PPG signal records absorbed light changes with photoelectric sensor technology when biological tissues are penetrated by specific light.Light absorption by tissues,such as skin,muscles,or bones,is relatively constant,however periodic pulses of heart cause periodic volume changes in artery.The periodic change of light path makes absorbed light change periodically,the signal recorded by photoelectric sensor on the remaining light's change is PPG signal.While it is inevitable that motion artifacts(MAs)will be a part of PPG signal when measurement condition is non-static,which makes periodicity of PPG signal degenerate or causes loss of waveform characteristics.PPG signal applications,such as heart rate or blood oxygen estimation,may have error,even lose practical value totally at the existence of MA.This paper offers a method dealing with MAs and it's possibility is discussed.The main contents in the paper are as follows:1.Platform construction for PPG signalPPG signal is acquired by the hardware with integrated analog front-end chip AFE4400 and common dual-wavelength blood oxygen sensor,the function of the platform is to upload PPG signal data to PC for signal analysis and MAs removal.2.Application of optical model for fingertip and identification of source of MAsThe rationality of absorption of light scattering model in PPG application for fingertip is introduced.Tissue noise and vein noise,the sources of MAs,are identified in the optical model.3.MAs removal by adaptive filters with generated reference signalAfter identification of sources of MAs,MAs related reference signals are stepwise generated by data from dual-wavelength sensor and data in which tissue noise is removed,accordingly.Adaptive filters with these reference signals are used to remove tissue and vein noise.Experimental results show that the method can achieve good performance on MAs removal.