• Journal of the Korea Convergence Society
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• v.8 no.9
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• pp.9-16
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• 2017

In this paper, sub-microwave oscillator sensor is proposed to non-invasively monitor the glucose concentration level of the human biological tissue by oscillation frequency variation. Inductive slot in the ground plane of the microstrip line is combined with the biological tissue, to realize the resonator as a part of the oscillator sensor. The phantom box mimicking the human tissue is introduced for simulation of the resonator which resonance frequency correspondingly shifts up on three step glucose concentration levels(0, 400, 800 mg/dL). Oscillator sensor circuit is fabricated as a prototype. Pig tissues instead of human is used. Oscillation frequency shift of about 14 MHz per glucose level of 400 mg/dL has been successfully measured around 1,100 MHz. This proves that the proposed sensor is applicable to a blood glucose sensor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.4
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• pp.279-285
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• 2017

In this paper, the resonator with a parallel plate capacitor is newly proposed around sub-microwave frequency band and applied to earlobe for non-invasive glucose monitoring the human biological tissue. The capacitor including the earlobe as dielectric material is connected to inductive slot in the ground plane of the microstrip line. Based on the simulation, one port resonator circuit is designed and fabricated as a prototype. Three step glucose concentration levels(0, 250, 500 mg/dL) was tested, and its reflection coefficients($S_{11}$) were measured. Owing to high Q resonator more than 100, resonant frequency shift of about 9 MHz per glucose level of 250 mg/dL has been successfully measured. This proves that the proposed sensor is applicable to a blood glucose sensor.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.247-255
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• 2018

In this work, glucose solution and sodium chloride solution were distinguished noninvasively using a microwave complementary split-ring resonator (CSRR). Based on the electrical properties of the two solutions measured using a open-ended coaxial probe, a CSRR was designed and fabricated for operation at a specific frequency that facilitates differentiating the two solutions. Furthermore, a polydimethylsiloxane mold was fabricated to concentrate the solution at a region where the electric field of the resonator was strongest, and a laminating film was used to prevent contact between the solution and resonator. Experiments were performed by dropping $50{\mu}L$ of the solution in steps of 100 mg/dL up to a maximum human blood glucose level of 400 mg/dL. Our experiments confirmed that the transmission coefficients ($S_{21}$) of glucose solution and sodium chloride solution exhibit variations of -0.06 dB and 0.14 dB, respectively, per 100 mg/dL concentration change at the resonance frequency. Thus, the opposite trends in the variation of $S_{21}$ with change in the concentration of the two solutions can be used to distinguish between them.

• Journal of the Korean Society for Nondestructive Testing
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• v.27 no.1
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• pp.23-30
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• 2007

We observed the NaCl concentration of solutions using a near-field microwave microprobe(NFMM). Instead of the usual technique, we take advantage of the noncontact evaluation capabilities of a NFMM. A NFMM with a high Q dielectric resonator allows observation of small variations of the permittivity due to changes in the NaCl concentration. The changes of NaCl concentration due to a change of permittivity of the NaCl solution were investigated by measuring the microwave reflection coefficient $S_{11}$ of the resonator. The NaCl sensor consisted of a dielectric resonator coupled to a probe tip at an operating frequency of about f=4 GHz. The change of the NaCl concentration is directly related to the change of the reflection coefficient due to a near field electromagnetic interaction between the probe tip and the NaCl solution. In order to determine the probe selectivity, we measured a mixture solution of NaCl and glucose.