Non-invasive measurement of hemoglobin content in blood

A non-invasive method of ascertaining the hemoglobin content in blood is presented here. The method proposed here uses a couple of photo-plethysmo- graphic (PPG) signals obtained by illuminating an extremity such as a finger or earlobe with monochromatic light at two different wavelengths. An empirical equation for calculation of hemoglobin content in blood is derived using a model for attenuation of light through skin-bone-tissue-blood in that extremity, well known extinction coefficients of hemoglobin (with and without oxygen) and data collected from a clinical study. The availability of PPGs at two different wavelengths facilitates the computation of, apart from hemoglobin content, heart rate, heart rate variability and oxygen saturation in arterial blood (SpO 2) as well. © 2014 IEEE.