The Research On Human Blood Glucose Detecting System By Mid-infrared Atr Spectroscopy

Diabetics is a serious disease which threaten human's health greatly. The traditional methods for detecting diabetics is by the biochemical analysis which has the disadvantages about invasive,reagent-consuming and uncomfortable for the patient. Using optical methods on diabetics detection is a new and promising field because of its quick,easy and real-time. It not only provides an economic way to avoid biochemical test methods, reduce material wastage and speed up measurement, but also it is the important base of non-invasive blood glucose measurement.According to the glucose absorption characteristics in mid-infrared region and the principle of ATR, we design a detecting system for human blood glucose.Firstly, the HeNe laser guidance system is planned to deal with the invisibility of mid-infrared light. Secondly, a beam expander system is used to change the divergence angle for the reason that the incident angle should have a certain divergence angle to satisfy sample cell's requirement. After that we design a single optical path detecting system which uses a multi-wavelength tunable pulse modulated CO₂ laser as the light source. Lock-in-amplifier is utilized to process and convert the original signal to a DC signal which reflects the concentration of glucose. Then we make a test and evaluate the SNR and stability of single optical path system and draw the conclusion that the SNR is between 0.004-0.02, the stability is between 3%-8%. Finally the modeling experiments of different concentrations of glucose in aqueous solution are accomplished using the system, and the result is not very good. After a large number of data verification, we conclude that the low accuracy of the concentration of glucose is resulted by its low absorbance and the instability of the laser's output power. Afterwards we plan to construct the duel optical paths system to aim to decrease even solve the instability of the laser's output power and make comparison of two schemes. We also analyze some influencing factors of the duel optical paths system and provide a appropriate conclusions.In brief, the detecting system provides a promising future to the human blood glucose detecting based on mid-infrared spectroscopy.