Motion artefact minimization from photoplethysmography based non-invasive hemoglobin sensor based on an envelope filtering algorithm

An envelope-filtered method of enhancement of non-invasive Hemoglobin (Hb) monitoring is described. Results using a four-wavelength two-wavelength Photoplethysmography (PPG) probe gathered from five randomly selected healthy subjects demonstrate that the measurement of Hb coefficient, based on the novel envelope method filtered PPG, has a superior performance on minimization of the motion artefact than that from band-pass filtered PPG data in both stationary and non-stationary scenarios. Hemodynamic pressure variation near the sensor probe is also induced from a vertical height difference (VHD) between the finger sensor probe and the heart level. Results of this study show that the Hb coefficients determined using the proposed filtering method based on the envelope algorithm are also capable of minimization of VHD variations similar to the traditional band-pass filter method.