We report a near-field microwave biosensor based on a dielectric resonator to detect glucose concentration. A microwave biosensor with a high Q dielectric resonator allows observation of the small variation of the glucose concentration by measuring the shift of the resonance frequency and the microwave reflection coefficient S(11). We observed the concentration of glucose with a detectable resolution up to 5 mgml at an operating frequency of about f=1.68 GHz. The change in the glucose concentration is directly related to the change in the reflection coefficient due to the electromagnetic interaction between the dielectric resonator and the glucose solution.
A near-field scanning microwave microprobe (NSMM) technique has been used to investigate the photovoltaic effect in solar cells. As the photoconductivity of the n-type silicon layer in the solar cells was varied due to the incident light intensities and the wavelength, we could directly observe the photoconductivity changes inside the solar cells by measuring the change of reflection coefficient S11 of the NSMM at an operating frequency near 4.1 GHz. We also directly imaged the photoconductivity changes by NSMM. Photoconductivity in solar cells is determined from the visualized microwave reflection coefficient changes at the interfaces with high sensitivity.
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