Figure 4: (a) Measured microwave reflection coefficient 𝑆 1 1 plotted as a function of the temperature of the glucose solution in the range 32–42°C at 4.6 GHz for (a) DI water and glucose solution with concentration of (b) 10 mg/ml, (c) 100 mg/ml, and (d) 200 mg/ml. The inset shows the measured loss tangent t a n 𝛿 plotted as a function of the temperature for the DI water and the same concentrations of glucose. (b) The dependences of (a) real (left axis) and (b) imaginary (right axis) parts of the relative permittivity on the glucose solution temperature (32–42°C) as a function of operation frequency in the 4-5 GHz range. The glucose concentration was 100 mg/ml.