Correction and Calibration of R Value Curve for Blood Oxygen Saturation Measurement Model Based on Lambert-Beer Law

The measurement of oxygen saturation in peripheral tissues is an important indicator of the oxygen supply to cells and tissues. However, with the emergence of a variety of new oximeters, the existing R value curve of oximetry simulation can no longer meet the current demand for metrological testing. To address this issue, a modified method of oxygen saturation measurement based on the Lambert-Beer law was proposed. This method involves the addition of an optical filter medium to the existing verification device to correct the R value curve and achieve a correction value added to the original measurement model. The experimental results demonstrate that by adding filter media to modify the R value curve, the oximeter can measure values that are close to the standard value under different R value curves. The indication repeatability is also small, meeting the requirements of national metrological verification regulation. The proposed method effectively solves the incompatibility problem between the simulator and the oximeter. The tests with the device also indicate that the correction factor could be quantitative for different kinds of pulse oximeters, if the calibration parameters can be achieved. The proposed correction method is simple to operate and suitable for the correction of different R value curves. It can provide certain technical support for the measurement verification of the blood oxygen module of the monitor of small brands. However, it should be noted that the attachment position, material, and thickness of the filter media will affect the correction effect. In conclusion, the proposed method of using an optical filter medium to modify the R value curve is a feasible correction method for the calibration of pulse oximeters. It has the potential to be applied to different kinds of pulse oximeters and could be of great value in the field of medical measurement.