Experimental Study On Non-invasive Reflectance Oxygen Saturation Measurement

Oxygen is the key material to human's life , and oxygen saturation is one of the important parameters reflecting oxygen delivery ability in human's blood. The non-invasive detecting oxygen saturation provides quickly, directly, efficiently physiological parameters to doctors. Transmittance oximetry is well developed as a monitoring technique. However, the using scope of the transmittance sensor is limited, reflectance oximetry is necessary in some circumstances(eg: forehead, chest etc), moreover, the level of study on reflectance oxygen saturation detecting is the primary phrase in our country, how to get an exact and dependable reflectance oxygen saturation value by non-invasive and economic means is always concerned by researchers in biomedical engineering.At first, the principle and technique of transmittance oxygen saturation measurement is analyzed deeply in this paper, and oxygen saturation formula applying reflectance sensor is deduced by means of the diffuse transport theory. Based on this theory, through the MSP430 as the experimental platform, on the research of hardware system, we applied the technique of the modulated light in order to eliminate background light and the inherent noise of system; developed the auto-gain control circuit in order to make the baseline of signal to be steady; applied the adjustable integrating amplifier to make the photoelectric plethysmography signal to be amplified uniformly; developed the adjustable control intercept circuit to solve...