Research And Development Of Multi-Wavelength Reflective Measuring Oxygen Saturation

Oxygen is an important substance to keep the normal life activity. Whether full oxygen is absorbed in the artery is an important condition for normal body metabolism. The development of effective detection techniques, real-time monitoring of human tissue oxygenation status, has important significance in life science research. As the transmitted sensor sites by the limitations, reflectance detecting have a better application prospects in cerebral oxygen saturation, muscle oxygen saturation, or fetal oxygen saturation monitoring. At present the theory research of reflective oximeter is still little, as the oxygen saturation changes in the human body, show worsening accuracy at lower saturation.In order to achieve accurate measurement of low blood oxygen, oxygen saturation formula applying reflectance sensor is deduced by means of the modified Lambert– Beer theory. This paper select the 735 nm, 805 nm, 890 nm wavelength of three kinds of light source, produced a reflex -type oxygen probe. Pulse oximeter signal extracted through the reflective oxygen probe into the system, after a pre-stage amplifier, the signal separation, filtering, gain adjustment circuit, etc., from A/D converter into a digital signal into the microprocessor. Due to its high performance computing power, low power and low cost advantages, ARM core embedded system wi11 be the main platform for pulse oxygen saturation measurement. The system based on ARM platform, completed the real-time detection of blood oxygen signal and storage, display and other functions. Article details the hardware circuit design and software development platform and design.As the pulse oximeter signal interference is large, we apply the moving average arithmetic to pretreatment oxygen saturation. Using an adaptive de-noising method that combines multiple wavelet transform removes high frequency electrosurgical unit and motion artifact interference effectively. Reflectance detecting system is calibrated when the system design and debugging was finished. The paper uses the pulse oximeter simulators for equipment calibration. In the end, the article finally analyzed the various kinds of interference factors that affect oxygen saturation measurement accuracy and preventive measures.