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The effect of central frequency of ultrasonic transducer on the glucose detection based on photoacoustic spectroscopy

The non-invasive detection of blood glucose based on photoacoustic spectroscopy is a very popular method used to monitor the diabetes mellitus in recent years. The basic mechanism of photoacoustic spectroscopy is the effect of photo-induced ultrasonic. The detection accuracy of blood glucose can be improved due to the captured ultrasonic rather than the photons. The properties of ultrasonic transducer is one of the important influence factors on the detection accuracy of glucose. To study the effect of detection frequency for ultrasonic transducer on the glucose detection based on photoacoustic spectroscopy, a set of photoacoustic detection system was established. The optical parameters oscillator (OPO) pulsed laser pumped with 532nm was used as the excitation light source. Three kinds of ultrasonic transducers with different central echo frequencies (1MHz, 2.5MHz, and 30MHz) were respectively used to capture the photoacoustic signal of test blood phantoms with different concentrations of glucose. The time-resolved photoacoustic signal and peak-to-peak values of test blood phantoms were obtained. The results show that with the increase of glucose concentration, the photoacoustic amplitudes and peak-to-peak values of phantoms increase. Moreover, the time of photoacoustic signal shifts left with the increase of concentration. The prediction models based on linear fitting method were established for three kinds of ultrasonic transducers. Prediction results show that for the ultrasonic transducer with central frequency of 1MHz, the correction coefficient is 0.8681, the root-mean-square error (RMSE) of glucose concentration is about 13.3%. For the ultrasonic transducer with central frequency of 2.5MHz, the correction coefficient is 0.83127, the RMSE of glucose concentration is about 1.8149%. For the ultrasonic transducer with central frequency of 30MHz, the correction coefficient is 0.99598, the RMSE of glucose concentration is about 0.3808%. Therefore, the detection effect of the ultrasonic transducer with central frequency of 30MHz is best compared with the two others.