A novel low-cost electronic tongue system for sugar content determination in sugar solutions is proposed. The system consists of a sine wave generator, a resistor, and an interdigital capacitor sensor forming a first-order electronic high-pass filter circuit. The interdigital capacitor sensor has the planar interdigital structure and the consecutive fingers are connected to positive and negative electrodes. The system has been assembled and the experiments were conducted. The experimental results show that the proposed system has a great potential to determine the sugar content in sugar solutions. It also provides an opportunity for the development of a microcontroller-based low-cost sensing system as an electronic tongue system.

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We report a metamaterial with optically isotropic negative refraction index, n, and small loss factor, k = |Im (n)/Re (n)| ≤ 0.4, that occurs near the visible/UV line. The metamaterial presented consists of two media. One medium (randomly distributed gold spherical nanoparticles with Drude‐like permittivity, in free space) ensures negative permittivity, and another medium (spherical SiC nanoparticles) ensures negative permeability via the Mie resonance within the same frequency range. We have found, self‐consistently, in the framework of both the effective medium approach and rigorous first‐principles based Finite Difference Time Domain (FDTD) simulations, that the metamaterial exhibits negative refraction index behavior. This result stands for both the random distribution of the SiC particles, and the regular simple‐cubic lattice of the same particles. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A detection system for water adulteration in honey is proposed. It consists of a modified SMA-connector sensor and a vector network analyzer. A modified SMA-connector sensor is applied to measure complex relative permittivity, electrical conductivity, and phase constant of honey samples with the open-ended method. The system is tested in the frequency range of 0.5–4.0 GHz at the sample temperature of 25 °C. The relationships between the complex relative permittivity, electrical conductivity, the phase constant, and the honey samples with different concentrations (0–30%w/w) are determined. The experimental results show that the real part of the complex relative permittivity is significantly proportional in honey samples with adulteration of water in the range of 0–30%w/w. The frequency of 0.6 GHz is a suitable frequency for detection with a real part of complex relative permittivity as an indicator. The frequency of 3.74 GHz is an appropriate frequency for detection with electrical conductivity as in indicator while the frequency of 4.0 GHz is suitable for detection with phase constant as an indicator. In addition, the data are analyzed with regression analysis. This technique is also performed on natural latex samples to determine the dry rubber content. The frequency of 0.5 GHz is a suitable frequency with a real part of complex relative permittivity as an indicator while the frequency of 4.0 GHz is a suitable frequency with an imaginary part of complex relative permittivity, electrical conductivity, and phase constant as the indicators. The results demonstrate that it is possible to apply this technique to determine the dry rubber content in the natural latex samples as well.

This paper deals with an investigation of the dielectric properties of concretes that includes rice husk ash using a planar coaxial probe. The planar coaxial probe has a planar structure with a microstrip and coaxial features. The measurement was performed over the frequency range of 0.5-3.5 GHz, and concrete specimens with different percentages of rice husk ash were tested. The results indicated that the dielectric constant of the concretes was inversely proportional to the frequency, while the conductivity was proportional to the frequency. The dielectric constant decreased with the increasing age of the concrete at the frequency of 1 GHz. The conductivity of the concrete decreased with the increasing age of the concrete at the frequency of 3.2 GHz. In addition, the dielectric constant and the conductivity decreased when the compressive strength increased. It was also shown that the obtained dielectric properties of the concrete could be used to investigate the relationship between the compressive strength and age of the concrete. Moreover, there is an opportunity to apply the proposed probe to determine the dielectric properties of other materials.