Non-invasive blood glucose sensing by near-infrared spectroscopy is easily interrupted
by the strong background variations compared to the weak glucose signals. In this work,
according to the distribution of diffuse reflectance intensity at different source-detector
separations, a method based on a reference point and a measuring point, where the diffuse
reflectance intensity is insensitive and most sensitive to the variation of glucose
concentration, respectively, is applied. And the data processing method based on the
information of two points is investigated to improve the precision of glucose sensing.
Based on the Monte Carlo simulation in 5% intralipid solution model, the corresponding
optical probe is designed which includes two detecting points: a reference point located at
1.3-1.7mm and a measuring point located at 1.7-2.1mm. Using the probe, the in vitro
experiment with different glucose concentrations in the intralipid solution is conducted at
1100-1600nm. As a result, compared to the PLS model built by the signal of the
measuring point, the root mean square error of prediction (RMSEP) and root mean
square error of cross calibration (RMSEC) of the corrected model built by reference point
and measuring point reduces by 45.10%, and 32.15% respectively.