Active noise cancellation of motion artifacts in pulse oximetry using isobestic wavelength light source

The measurement of oxygen saturation using pulse oximeters requires clean photoplethysmograph (PPG) signals, as motion artifacts often lead to a significant degree of error in the computation. This paper proposes a method for reducing motion artifacts from corrupted PPG signals by applying a normalized least mean squares (NLMS) algorithm, using an isobestic point wavelength (800nm) as a noise reference signal for the adaptive filter. A finger ring type sensor was demonstrated to be more comfortable than a clip type sensor. Experimental results indicate that the proposed method is suitable for reconstructing PPG signals and improving the accuracy of measuring oxygen saturation in the blood.