Fluid pulsation detection in presence of induced motion artifacts using speckle techniques

The importance of regular health monitoring has led to a large variety of medical products being available in the market. Motion artifact is still a limitation in portable optical devices which can provide accurate results. We will address the possibility of measuring a pulsatile flow in a noisy environment using an approach based on speckle dynamics. In specific case we measure pulsation or the heart rate in presence of motion between the illumination and the in-vitro or in-vivo sample. The main motion induced artifact in the signal being measured arises from changing the light penetration depth at various positions being illuminated. These measurements have been compared for different settings and multiple-exposure time of the camera. We compare the result for each measurement based on two techniques of speckle contrast and correlation. Under several parameters of the measurement, different analysis techniques were successful but in general correlation approach shows to be more robust for larger motion induced artifacts. Shorter exposure times provide a more detailed spectrum and more successful for extracting the signal from the induced motion artifact, in case of correlation analysis. The in-vivo measurement results agreed fairly with in-vitro case.