A Primary Study On Near Infrared Pulse Noninvasive Detection

Near-infrared nondestructive detection and analysis technology have been applied to the measurement of tissue oxygenation and microcirculation, and gratifying achievements have been presented over the last few decades. The motivation behind such studies is to provide improved patient outcome by using the data obtained to better understand a disease process and clinical observation.Theoretical basis and key technologies of non invasive detection of oxygen saturation of blood of NIRS are systematically illustrated. Current research status and application of the detector are also presented. The detection technologies of Near-infrared transmittance spectroscopy and reflectance spectroscopy are discussed in detail. Finally, the factors that affect detection accuracy of the technology of NIRS in Non Invasive Detection of Oxygen Saturation of Blood are analyzed. In conclusion, the technology of NIRS still has broad prospects and wide developing foreground.In recent years, considerable research studies were carried out on the near-infrared pulse determination. Along with the availability of short-pulsed lasers in the near infrared, it was soon realized that the information content of a time-resolved measurement in a uniform scattering medium was sufficient to separate the contribution of scattering and absorption to the light attenuation in tissue. In fact, duty ratio is one of the important parameters of near-infrared square-wave pulse, and it would affect the precision of adjustment about energy and propagation distance range of NIRSP directly. However, little attention has been devoted to the application of duty ratio on near-infrared nondestructive detection. It is hoped that this situation will be improved with our proposed approach.In order to understand the transmission mechanism at human tissue of near-infrared square-wave pulse (NIRSP), an experimental study of the duty ratio threshold for regular transmission at the fingertip and palm of human hand by NIRSP was carried out by using a couple of simple transmitting and receiving device with tunable duty ratios, and also the light emitting diodes (LED) both at the wavelengths of850nm and940nm. The thresholds were determined by measuring the waveforms of the changed voltages of NIRSP receiving system as a measurement of the transmission at human tissue. When the receiving waveforms were taken on the certain behavior as the emitting waveforms, the duty ratio threshold for regular transmission at human tissue of NIRSP was observed.The experimental results show that the duty ratio is an important index for the transmission at human tissue of NIRSP. And the duty ratio thresholds for regular transmission both at the fingertip and palm of NIRSP at the wavelength of850nm and940nm have been given. We investigated the changed voltage waveforms transmitted through the human tissue of NIRSP receiving system with tunable duty ratios and at different wavelengths, and the duty ratio thresholds for regular transmission at human tissue have been recorded. On the basis of this study, we tentatively put forward a new opinion on improving the detection accuracy of near-infrared nondestructive detection and analysis technology at human.