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In this study, the glucose was detected by using the photoacoustic spectroscopy method for the milk-glucose mixed solutions. To achieve the purpose, a kind of photoacoustic detection system of glucose was established by using the OPO pulsed laser. Meanwhile, a focused ultrasonic detector with central echo frequency of 2.5MHz was used to capture the photoacoustic signals of glucose. And a kind of custom-built cycling sub-system used to analogy the flow system of pure blood in the vessel of human being. In experiments, a series of mixed solutions with different concentrations of milk and glucose were prepared and excitated by the pulsed laser beam with the wavelength of 1064nm and the output energy about 1mJ. The time-resolved photoacoustic signals, the peak-to-peak values and peak-point times for the mixed solutions with different concentrations were all obtained. Experimental results show that with the increase of the concentration of milk and glucose, the peak times decrease, i.e., the ultrasonic velocity increases. For the mixed solutions with fixed concentration of milk but different concentrations of glucose, the photoacoustic peak-to-peak values of glucose increases with the increase of the glucose concentration. However, for the mixed solutions with fixed concentration of glucose but different concentrations of milk, the photoacoustic peak-to-peak value of glucose decreases with the increase of milk concentration. The results can be interpreted by the reason that the light absorbance of glucose is decreased by the increase of the milk concentration due to the increase of the light-scattering effect in the turbid solutions. The prediction models of glucose were built for the different mixed solution for the milk and glucose. Then, the prediction correlation coefficients and root-mean-square error (RMSE) values were also gotten. Results show the correlation coefficient can reach 0.986 in the milk-glucose mixed solutions, and the smallest RMSE value is about 18.24mg/dl .
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