Dielectric coated conductive rod resonantly coupled with a cut transmission line as a tunable microwave bandstop filter and sensor.

The resonant interaction of a dielectric-coated conductive rod with the X-band microwave field is investigated. The magnetic field distribution of the Goubau standing radial surface waves was experimentally visualized by using a thermo-elastic optical indicator microscope, and the corresponding electric field distribution was determined via numerical simulations. These field distributions are characterized by a certain pattern of antinodes distinctive for standing waves.

Characterization of interaction phenomena of electromagnetic waves with metamaterials via microwave near-field visualization technique.

A new practical imaging technique was presented for metamaterial characterization and investigation by visualizations of the magnetic microwave near-field (H-MWNF) distributions on a metamaterial's surface using the method of thermo-elastic optical indicator microscopy (TEOIM). ITO-based transparent and ceramic-based opaque metamaterial structures were designed for magnetic near-field visualization. Depending on the incident microwave field polarization, the TEOIM system allows the characterization of the metamaterial properties and microwave interaction behavior.

3D visualization of microwave electric and magnetic fields by using a metasurface-based indicator.

Visualizations of the microwave electric and magnetic near-field distributions of radio-frequency (RF) filters were performed using the technique of thermoelastic optical indicator microscopy (TEOIM). New optical indicators based on periodic dielectric-metal structures were designed for electric field visualization. Depending on the structure orientation, such metasurface-based indicators allow separately visualization of the E and E components of the in-plane electric field.

Visualization of microwave near-field distribution in sodium chloride and glucose aqueous solutions by a thermo-elastic optical indicator microscope.

In this study, a new optical method is presented to determine the concentrations of NaCl and glucose aqueous solutions by using a thermo-elastic optical indicator microscope. By measuring the microwave near-field distribution intensity, concentration changes of NaCl and glucose aqueous solutions were detected in the 0-100 mg/ml range, when exposed to microwave irradiation at 12 GHz frequency. Microwave near-field distribution intensity decreased as the NaCl or glucose concentration increased due to the changes of the absorption properties of aqueous solution.

Real-Time Noninvasive Measurement of Glucose Concentration Using a Modified Hilbert Shaped Microwave Sensor.

We developed a microwave glucose sensor based on the modified first-order Hilbert curve design and measured glucose concentration in aqueous solutions by using a real-time microwave near-field electromagnetic interaction technique. We observed S transmission parameters of the sensor at resonant frequencies depend on the glucose concentration. We could determine the glucose concentration in the 0-250 mg/dL concentration range at an operating frequency of near 6 GHz.

Characteristics of light transfer in the connected conical waveguides with the same symmetry axis.

The propagation of the light trough dielectric-metal-dielectric conical waveguide is described by the coupling modes between internal and external waveguides. The energy pumping from internal to the external waveguide has a resonant behavior and is very sensitive to the variations of the system parameters. The simplified model of this process realization is the light flash at the end of the conical metal covered tip of the optical fiber that crosses the liquid-air interface.

Label-free DNA microarray bioassays using a near-field scanning microwave microscope.

A near-field scanning microwave microscope (NSMM) is used to readout and visualize homemade 10-mer oligonucleotide microarrays and an Agilent 60-mer DNA microarray as a realistic test of NSMM applicability to multiplexed sequence analysis. Sensitive characterization of DNA coverage and high resolution mapping of DNA spots in the microarray were realized by measuring the change of microwave reflection coefficient (S₁₁) at about 4 GHz operating frequency. Hybridization between target (free) and capture (immobilized) sequences leads to changes in the microwave reflection coefficient, which were measured by the NSMM.

Application of a sensitive near-field microwave microprobe to the nondestructive characterization of microbial rhodopsin.

We study the opto-electrical properties of Natronomonas pharaonis sensory rhodopsin II (NpSRII) by using a near-field microwave microprobe (NFMM) under external light illumination. To investigate the possibility of application of NFMM to biological macromolecules, we used time dependent properties of NPSRII before/after light activation which has three distinct states - ground-state, M-state, and O-state. The diagnostic ability of NFMM is demonstrated by measuring the microwave reflection coefficient (S(11)) spectrum of NpSRII under steady-state illumination in the wavelength range of 350-650 nm.

Noninvasive in vitro measurement of pig-blood d-glucose by using a microwave cavity sensor.

We have developed an electromagnetic microwave cavity sensor based on the resonant frequency shift for real time measurement of the glycemia in pig blood. We could determine the concentration of d-glucose in pig blood in the range of 150-550mg/dl at the resonance frequency near 4.75GHz with a bandwidth of 300MHz.

Non-invasive in vitro sensing of D-glucose in pig blood.

We have developed an electromagnetic resonant spiral sensor and have measured the glycemia in pig blood and the concentration of D-glucose in aqueous solution by using a real-time electromagnetic interaction phenomenon between the microwave sensor and the liquid. We could determine the concentration of glucose with a minimal resolution of 5 mg/dl in the 100-600 mg/dl concentration range at operating frequencies of about 7.65 GHz (for the glucose aqueous solution) and 7.

Detection of DNA-hybridization using a near-field scanning microwave microscope.

A near-field scanning microwave microscope (NSMM) is used to detect sequence-specific hybridization between surface-immobilized and free DNA single strands. Hybridization between target (free) and capture (immobilized) sequences leads to changes in the reflection coefficient (S11) which are measured by the NSMM. These changes are caused by hybridization-induced modification of the dielectric constant profile of the DNA film.

Visualization of magnetic domains by near-field scanning microwave microscope.

A near-field scanning microwave microscope (NSMM) system was used for the investigation of magnetic properties of a hard disk (HD) under an external magnetic field. To demonstrate local microwave characterization of magnetic domains by NSMM, we scanned the HD surface by measuring the microwave reflection coefficient S(11) of the NSMM at an operating frequency near 4.4GHz.

Microwave dielectric resonator biosensor for aqueous glucose solution.

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.

Investigation of CdS thin films by a near-field microwave microprobe.

Cadmium sulphide (CdS) thin films with different microstructures and morphologies were measured by using a near-field microwave microprobe (NFMM). The NFMM system was coupled to a dielectric resonator with a distance regulation system at an operating frequency f=4.1 GHz.

Characterization of Alq3 thin films by a near-field microwave microprobe.

We observed tris-8-hydroxyquinoline aluminum (Alq3) thin films dependence on substrate heating temperatures by using a near-field microwave microprobe (NFMM) and by optical absorption at wavelengths between 200 and 900 nm. The changes of absorption intensity at different substrate heating temperatures are correlated to the changes in the sheet resistance of Alq3 thin films.

Characterization of magnetic materials using a scanning microwave microprobe.

We investigated the electromagnetic properties of metals of iron, nickel, cobalt, aluminum, gold, copper, silver, and permalloy thin films on SiO2 substrates using a near-field microwave microprobe. The electromagnetic properties of metal sheets were estimated by measuring the microwave reflection coefficient S(11) and compared with the theoretical values. We observed the hysteresis behavior of permalloy thin films on SiO2 substrates using a near-field scanning microwave microprobes (NSMM) system.