Design And Implementation Of A Portable Finger Ring Oximeter Based On CC430SCM

Blood oxygen saturation is an important parameter of the life signs. It reflects the blood’s ability to transport oxygen and the performance of human respiratory system efficiently. Especially with the population of aged people increasing, the morbidity rate of various cardiovascular diseases is becoming higher and higher. Monitoring blood oxygen saturation continuously is very important to prevent some potential diseases for humans.There are many kinds of oximeters in the current market. But with finger folder structure, their oxygen probes are mostly high power and inconvenient to carry. They can’t meet people’s requirements of portable and continuous medical devices. This paper designs a noninvasive and low power finger ring oximeter based on Lambert-beer’s law. It can monitor human’s blood oxygen saturation and pulse rate remotely.After researching the principle how to measure blood oxygen saturation, the paper puts forward the whole designing scheme for the finger ring oximeter. Firstly, the paper designs and implements the hardware for the system. CC430F5137is used as the system’s core processor. The oxygen sensor is designed as a ring, which is small and portable. Then the paper designs filter circuits and amplifier circuits to process the signals acquired by the ring sensor. Peripheral circuit of the RF module is completed by referring to the data sheet of CC430SCM. Secondly, this paper designs the software for the finger ring side. The system uses IAR Embedded Workbench as its development environment. A/D conversion, nine-order FIR low-pass filter, eight points moving average filter are finished in this part. The paper uses thresholds to extract features and eliminate motion artifact. Calibration is presented for the finger ring oximeter to get the blood oxygen saturation and pulse rate. The results can be sent to the receiver module through CC1101that embedded in CC430F5137. Then the receiver module sends them to the host computer via a serial port. Finally, in order to ensure that the system get clear pulse wave in low SNR environment, two kinds of denoising schemes are put forward for the host computer. The two denoising algorithms are wavelet transform algorithm based on lifting scheme and lifting wavelet algorithm based on LMS.Experiments prove that the finger ring oximeter can monitor blood oxygen saturation and pulse rate remotely. Besides, the size of this system is much smaller than other common oximeters in the market. It has the characteristics of low power consumption and portable.