Theoretical Analyses And Experimental Verification On Joint Use Of Transmittance And Reflectance For Non-invasive Blood Glucose Sensing With Near Infrared Spectroscopy

Routine blood glucose monitoring is a pain for patients,which makes the development of a fast and convenient way to detect blood glucose concentration has become the focus.Near-infrared spectroscopy(NIRS)is one of the most promising noninvasive detection technologies for blood glucose measurement by analyzing blood glucose information from spectral signals.The damage of Near-infrared light for human body is small,but its light energy is weak,and thus to make full use of available useful optical information.The diffused reflectance spectrum and transmission spectrum generally can be obtained,hoping to find a way to joint use of the two spectra to enhance the spectral signal.The purpose of this paper is to find out the rules of diffused reflectance and transmittance in biological tissue with different structures and thicknesses,and to provide theoretical reference for the following the joint use of diffused reflectance and transmittance.In this thesis,we first introduce the derivation process of Boltzmann radiation equation and the meaning of formula.According to the extrapolation boundary condition and the mirror source dipole theory,we first analyze the propagation law of photon in semi-infinite medium.It is necessary to analyze the law of photon transmission in medium with limited thickness.Therefore,the law of photon transmission in single-layer slab structure is mainly analyzed,and the law of diffused reflectance and transmittance of photon in slab structure is discussed.The formula of reflection and transmission in slab structure is deduced.At last,the propagation law of multi-layer organization is carried out,which is instructive for human experiment.Then,based on the Monte Carlo simulation method,the simulation of photon propagation in semi-infinite media is carried out.Monte Carlo simulation of 1-6 mm thickness of the monolayer skin model like the slab structure model described above,compares the results of the theoretical analyses with the simulation results,and the two results are consistent as a whole.This shows that the theoretical analysis results are feasible of.So we can find the relationship between diffused reflectance and transmittance by using the formula deduced from the theory.This is of great significance to the study of joint use of the two spectra.In the end,the five-layer structure model of the skin is introduced,and the simulation analysis is carried out.Finally,based on the theoretical analyses and Monte Carlo simulation,a NIR spectroscopy detection system was set up in the laboratory.1-6mm thickness of the imitation was tested.And research transmission law of near-infrared light,and compare the experimental and simulated data.It can be found that the intensity of reflected light intensity increases with the increase of the thickness of the tissue,and the transmitted light intensity decreases gradually,which is consistent with the theoretical analyses and simulation results,which shows that the formula of reflectance and transmittance is correct,for the follow-up joint use of diffused reflectance and transmittance provides a strong theoretical support.