The Measurement And Analysis Of Glucose Concentration Changes In Blood With Near-infrared Spectroscopy

With the current finger-pick technique, tight glucose monitoring is difficult, as it is painful, inconvenient and expensive. Among several optical methods, near-infrared adsorption spectroscopy has been widely explored for both in vitro and in vivo glucose measurements since the NIR region contains the overtone and combination bands of glucose absorption. It's glucose specificity, detection location and model calibration that need to be solved because of low glucose absorption, overlapped spectrum and individual differences. In this thesis, we measured and analyzed the absorption properties of blood glucose concentration changes with near-infrared spectroscopy by experiments in vitro.The human blood absorption characters were analyzed through the blood sample absorption spectrum firstly, and the results proved water absorption peaks and showed that water absorption from plasma was much stronger than blood cell which had no selective absorption in near-infrared overtone regions. Then the absorption spectrum representation with blood glucose concentration changes were analyzed with blood glucose model which was developed based on the blood absorption characters. According to the results, we proved that the absorption intensity became stronger at glucose absorption peak (1732nm, 2168nm) with the higher blood glucose concentration, in reverse absorption at water absorption peak (1452nm, 1948nm) became weaker due to the interaction of water and glucose molecules. The absorption intensity at glucose and water absorption peak which were dealt with by statistics method proved that the NIR spectra was sensitive to the glucose concentration.The preliminary study of optical characters and near-infrared absorption with cutaneous blood vessels model was made following the blood glucose model experiments in vitro. Based on the analysis of cutaneous blood vessel structure,the light transport property in skin and the optical parameters of skin tissue,an optical model for normal skin of different blood content in both upper blood plexus and deep blood plexus was developed.The simulation results indicated that the collected diffuse reflectance signal could reflect the information of blood content in upper blood plexus. Then the influences of optical parameters with blood glucose concentration changes were analyzed.The research indicates that blood glucose concentration changes in 100-500mg/dl could be distinguished in certain extent by measuring the absorption intensities at 1732nm, 2168nm and 1452nm, 1948nm, which may result in a practical detection of blood glucose concentration in vivo.