Study Of Real-time Wireless Pulse Oximetry System Based On Cortex-M3

Oxygen indicators reflect the important parameters physiological status. The oxygen content of blood can be characterized by oxygenated hemoglobin concentration and reduced hemoglobin concentration. It is an important indicator for monitoring the vital signs. The traditional method to detect oxygen is to take blood, measure the arterial oxygen within minutes, and calculate the arterial oxygen saturation. Although the results of invasive detection method is accurate, this method has to be arterial puncture or intubation, the patient has pain, and can not be monitored continuously, especially for critically ill patients or newborns. To take blood from them is unrealistic in many occasions. Noninvasive arterial oxygen saturation detection method is based on the principle of photoelectric detection. This method detects the fluctuations in blood volume due to changes in the amount of light absorbed, and eliminates the impact of non-blood tissue oxygen saturation degree (SpO2). The advantages of this method is safe, reliable, continuous, real-time, fast and without damage, etc. It has been widely welcomed and applied in clinical practices. It has become one of the basic monitoring means used in the operating room, intensive care unit. Also, it has been applied in clinical research, treatment and diagnostic checks and other fields. This method has made a significant contribution to the clinical medicine. This article aims to design a non-invasive blood oxygen saturation measuring instrument which has STM32F103of ARM-cortex M3as processing core,. Use the wireless transceiver chip nRF24L01the module ptr6100M to build a wireless monitoring platform. The whole system is divided into three modules:(1) signal extraction module;(2) the signal processing module;(3) wireless transmission module and the PC software module. Signal extraction and signal processing use the STM32F103as processing core, STM32F103generating timing control signals, are driven alternately in red (660nm) and infrared light (940nm) diode. Photodiode converts the received optical signal into a voltage signal. After conducting amplification, separation, filter, trapped wave, the pulse wave signal from red and infrared light was obtained. Next, send the signal to the A/D channels of STM32F103to process the sample and computing the body’s oxygen saturation values. Next, send it into the wireless sensor network through the wireless module. The wireless network nodes of monitoring station transmits the data to the host computer through the serial. After further processing by the host computer, the data of oximeter waveform and pulse oximetry can be displayed and the data then was stored in the database.Finally, pulse oximetry testing system debugging and testing laboratories, experiments show that the pulse oximetry measurement instrument designed to eliminate noise interference better, higher measurement accuracy. In this paper, the design of wireless monitoring platform, in the actual test, The results indicate that the normal transmission of data, a good running. The entire system can quickly monitor multiple patients continuous oxygen saturation changes, break through the measurement of space limitations, expand the measurement range to achieve the design requirements of this article.