Fig. 1. (a) Block diagram of the blood glucose photoacoustic measurement system used by Kinnunen's group; (b) relationship between the blood glucose photoacoustic value and the concentration in pig whole blood at wavelength of 1064 nm; (c) relationship between the blood glucose photoacoustic value and the concentration in pig whole blood at wavelength of 532 nm

Fig. 2. (a) Photoacoustic blood glucose determination system designed by Zhao's group; (b) experiment result of the glucose concentration from 0 to 100 mg/dL; (c) ultrasonic velocity versus temperature at different solution concentrations

Fig. 3. (a) Schematic of our research group's photoacoustic noninvasive detection unit; (b) time-resolved photoacoustic signal of glucose solutions with different mass concentrations; (c) predicted mass concentration of glucose solutions at characteristic wavelengths of 1410 nm and 1510 nm

Fig. 4. (a) Diagram of the photoacoustic blood glucose detection apparatus used by Zhao's group; (b) relative photoacoustic change of glucose solution with different concentrations; (c) relationship between photoacoustic signal change and glucose mass concentration in the fresh blood sample

Fig. 5. (a) Block diagram of experimental setup used by Pai's group; (b) Clarke error grid analysis plot showing a comparison of predicted blood glucose values and reference values from 30 subjects

Fig. 6. (a) Schematic of blood glucose photoacoustic noninvasive detection system used by Kottmann's group; (b) photoacoustic signal dependence on glucose concentration between 0 and 2000 mg/dL; (c) photoacoustic spectra of a human epidermal skin sample in contact with water, 2 g/dL and 10 g/dL glucose solutions; (d) schematic diagram of the fiber-coupled photoacoustic cell; (e) photoacoustic spectra of human skin measured at the finger tip and the forearm

Fig. 7. (a) Schematic of the photoacoustic measurement system of skin glucose used by Pleitez's group[25]; (b) diagram showing the photoacoustic cell for human skin blood glucose photoacoustic measurement; (c) photoacoustic spectra of a diabetic volunteer as a result of the variation of blood glucose concentrations; (d) Clarke error grid between measured blood glucose and predicted blood glucose