A Novel Calibration-Free Method of Measurement of Oxygen Saturation in Arterial Blood

In present-day pulse oximeters, oxygen saturation in arterial blood $( \hbox{SpO}_{2})$ is computed by utilizing an empirical relationship extracted from a calibration curve. The calibration curve is obtained by curve-fitting data acquired from volunteers. A novel method of computation of $\hbox{SpO}_{2}$ that does not require the use of a calibration curve is presented in this paper. Based on a model for the attenuation of light through skin, tissue, bone, and blood, suitable processing steps are identified so that the analytical expression derived for the estimation of $\hbox{SpO}_{2}$ becomes free of not only patient but sensor-dependent parameters as well. The experimental results presented in this paper establish the efficacy of the proposed method.