LabVIEW-based Wireless Monitoring System For Oxygen Saturation

Oxygen saturation is one of the most important parameters reflecting oxygen delivery ability in human blood. The measurement of oxygen saturation has great significance in clinical and daily health care. Cable is used to transmit detected data in traditional oxygen saturation measure system, which not only limits the freedom of patients, but also brings cumbersome wiring and maintenance to the hospital. This system overcomes the disadvantages of the cable system by combining oxygen saturation measure system and wireless transmission technology, and the wireless module interface of the systems is more simple and easy to maintain. The traditional oxygen saturation measurement is based on signal processing chip. But the chip limits the signal processing speed and accuracy. In order to obtain high-quality pulse signal and to process it efficiently, LabVIEW graphical programming technology for pulse signal processing methods are used in this thesis for depth research. It improves the signal processing capabilities and reduces the difficulty of programming greatly. The main work is as follow:(1) By analyzing the error caused by the traditional theory of pulse oximetry measurement, a new method is proposed to eliminate the error in theory which can increase the accuracy of oxygen saturation measure system.(2) According to the principle of pulse oximetry sensor design, the lights wavelength is chosen suitably, a stable light source is designed to drive circuit..(3) Because the traditional pulse oximetry system uses complex analog circuits which may make the system instability, an optimized hardware acquisition circuit is designed. Both red and infrared signals are transmitted in one channel and spread into two separate signal channels in PC, which greatly simplifies the hardware structure, improves the system reliability and reduces the cost.(4)The wireless transmission system based on nRF905 is designed, which uses frequency division multiple access technology to achieve master-slave communication. This system which breaks the space limitation can monitor multiple patients with continuous changes of blood oxygen saturation in real-time.(5) LabVIEW is used to process the pulse signal. In the pretreatment process of denoising, wavelet denoising removes broadband noise effectively. Linear fitting method is used to remove the trend, and the result is great. Differential threshold algorithm is employed, which greatly identifies the first data of the single-period waveform, even under severe disturbance of baseline drift, this method can also identify accurately. Finally, the detection and calculation of characteristic values are executed. The warning is given when oxygen saturation value is lower than 90%.The experiment results show that, the system can achieve stable, reliable and effective real-time signal transmission and processing. It can be considered to apply to hospitals, communities and home care and other fields.