Research And Development In Reflectance Oxygen Saturation Detecting System

Oxygen is the key material to human's life, and oxygen saturation is one of the important indexes reflecting organic oxygen delivery status. Determining oxygen saturation in human blood by transmittance oxymetry is well developed as a monitoring technique, which is applied widely in clinical diagnosis or house health care. However, reflectance detecting is necessary in many circumstances, such as cerebral oxygen saturation, muscle oxygen saturation, or fetal oxygen saturation monitoring. 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 employed in transmittance oxymetry is analyzed. The Lambert-Beer Law and the difference in extinction coefficient of components in tissues relate to different light wavelength is applicable in reflectance oximetry as well as in transmittance oximetry, as both are relate to near-infrared spectroscopy. However, a new method is brought forward when dealing with alternating components of emitting light in reflectance detection, which entirely reflect the concentration of oxy-hemoglobin and deoxy-hemoglobin in blood, to improve the system sensitivity on oxygen saturation alternation. The new method is an innovative reference to reflectance oxygen saturation detection.Secondly, the wavelength of light source and the distance between the source and detector, two key parameters in reflectance sensor design, are determined according to theory in light transmitting and experiments in lab. Thus the sensitivity anddependability in reflectance monitoring is improved as much as possible.This paper also includes the software and hardware design and implementation of this reflectance oximeter which is made and used in my lab.At the last, the reflectance detecting system is tested to verify its sensitivity to oxygen saturation alteration in blood and its consistence to transmittance detecting results. At the same time, the new method put forward in previous is proved to be an effective parameter to determine oxygen saturation in reflectance detection.