Noninvasive Tissue Oxygen Saturation Detection System Based On Continuous Wave Near Infrared Spectroscopy

Near Infrared Spectroscopy is especially suitable for the real-time monitoring of human body, owing to its obvious advantages such as high sensitivity, noninvasive characteristic, rapid response and so on. So detecting the haemoglobin oxygen supply of the people's tissue and real-time monitoring the tissue oxygen saturation, plays a significant role in medical diagnose and clinical treatment. In this article, a NIR continuous wave reflectance measurement system is built, which can conveniently realize the human tissue detection. For the measuring human tissue optical parameters and developing NIR topography, the system has a great application perspective.Main achievements of this thesis include:(1) The thesis primarily summarizes the existing measurement methodologies of the near-infrared spectroscopy technology. Then several method of NIRS technology is compared to detect the characteristics of human tissue, and analyzed the feasibility of them. Finally, tissue detecting system with near-infrared continuous wave is determined as the design plan.(2) In the dissertation, two schemes are used to measure the oxygen saturation. One is to estimate the differential pathlength factor with time-resolved spectroscopy and then account the tissue oxygen saturation based on the Modified Beer-Lambert Law; the other is to measure the tissue oxygen saturation with the spatial-resolved spectroscopy, which is deduced from the photon diffusion equation theory.(3) The noninvasive NIRS continuous wave tissue detection system has been designed and founded. Based on the reflectance measurement with double wavelengths and double source-detector separations, the system can detect tissue optical parameters and the tissue oxygen saturation. In order to realize the measurement of double source-detector separations, the plan is proposed, which changes the light path with MEMS mechanical optical switch. It can also reduce the cost and realize the miniaturization. Under the LabVIEW software interface, the controlling program is written for the detection system.(4) At last, the experiments are studied on the human forearm with the noninvasive NIRS oxygen saturation detection system. The results show that the system can measure the tissue oxygen saturation conveniently, directly and rapidly to satisfied the clinical demand.