Evaluation Of Dielectric Properties Research Articles

Evaluation of dielectric properties of Au/TZO/n–Si structure depending on frequency and voltage

Evaluation of dielectric properties of Au/TZO/n–Si structure depending on frequency and voltage

Contactless Radio Frequency Monitoring of Dielectric Properties of Egg White During Gelation

The evaluation of dielectric properties in the radio frequency (RF) bandwidth is highly relevant to characterize the physical or physiological state of organic materials. This paper reports on the implementation of an easy-to-use and contactless RF dielectric sensing technique used for the monitoring of the heat-induced gelation of a white egg sample. The sensing technique basically consists in the distant monitoring of a high-quality factor inductive RF resonator operating at 98 MHz, which is electromagnetically coupled to the egg white sample. A lumped element modeling of the contactless RF probe interacting with the egg white is proposed. It is used to estimate both the conductivity and the permittivity of the sample during its gelation, starting from the impedance changes measured at the ends of the RF probe, and after probe calibration carried out using a reference NaCl solution. The results obtained during a 10 h monitoring experience allow the dynamics of the egg white gelation to be analyzed. These results open the way to the development of easy-to-implement and non-invasive dielectric monitoring of organic materials, with many prospects in agrifood as well as health monitoring applications.

Evaluation of Dielectric Properties of HTCC Alumina for Realization of Plasma Sources

The prospect of finding life outside Earth has fascinated mankind for ages, and new technology continuously pushes the boundary of how remote and how obscure evidence we can find. Employing smaller, or completely new, types of landers and robots, and equipping them with miniature instruments would indeed revolutionize exploration of other planets and moons.In this thesis, microsystems technology is used to create a miniature high-precision isotope-resolving molecular spectrometer utilizing the optogalvanic effect. The heart of the instrument, as well as this thesis, is a microplasma source.The plasma source is a split-ring resonator, chosen for its simplicity, pressure range and easily accessible plasma, and modified to fit the challenging application, e.g., by the adding of an additional ground plane for improved electromagnetic shielding, and the integration of microscopic plasma probes to extract the pristine optogalvanic signal.Plasma sources of this kind have been manufactured in both printed circuit board and alumina, the latter for its chemical inertness and for compatibility with other devices in a total analysis system. From previous studies, classical optogalvanic spectroscopy (OGS), although being very sensitive, is known to suffer from stability and reproducibility issues. In this thesis several studies were conducted to investigate and improve these shortcomings, and to improve the signal-to-noise ratio. Moreover, extensive work was put into understanding the underlying physics of the technique.The plasma sources developed here, are the first ever miniature devices to be used in OGS, and exhibits several benefits compared to traditional solutions. Furthermore, it has been confirmed that OGS scales well with miniaturization. For example, the signal strength does not decrease as the volume is reduced like in regular absorption spectroscopy. Moreover, the stability and reproducibility are greatly increased, in some cases as much as by two orders of magnitude, compared with recent studies made on a classical OGS setup. The signal-to-noise ratio has also been greatly improved, e.g., by enclosing the sample cell and by biasing the plasma. Another benefit of a miniature sample cell is the miniscule amount of sample it requires, which can be important in many applications where only small amounts of sample are available.To conclude: With this work, an important step toward a miniature, yet highly performing, instrument for detection of extraterrestrial life, has been taken.

Anionic Aliphatic Polyesteramide Copolymers: Evaluation of Dielectric Properties

This study looks at the effects on the dielectric behavior as result of the incorporation of ester sequences along the nylon 6 chains. The aliphatic polyesteramide copolymers and nylon 6 homopolymer were synthesized via anionic ring-opening copolymerization using the rotational molding technique by varying the ratio of the e-caprolactam (CLA) and e-caprolactone (CLO) comonomers. The ester units are correlated with biodegradable potential of polymers and the polar amide groups are able both to confer the polymer semicrystalline character and to be sensitive to the electric stimulus. The dielectric properties of the anionic nylon 6 and polyesteramides have been carried out as a function of frequency (100 Hz-106 Hz), at ambient temperature. Regarding to dielectric permittivity, e*(f), it was observed that the samples exhibit same behavior at increasing of the frequency. Experimental data revealed that the real part of electric modulus, M'(f) of the copolymers are many lower than those corresponding of the homopolymer. The presence of a single arc in the complex impedance plane plots confirms that, within the studied frequency range, the samples have a highly capacitive behavior. The results related to dielectric, crystalline and thermal properties of copolymers were compared with those obtained for homopolymer.

Dielectric properties of sawdust reinforced epoxy composites post-cured in microwaves

This study focuses on the measurement and evaluation of dielectric properties of composite materials with a view to benefiting these relevant industries. Previously published have been the mechanical and thermal properties of sawdust reinforced epoxy composites. The properties of a dielectric material can be controlled through the introduction of various fillers. This study was primarily undertaken to determine the effect of sawdust on the dielectric properties of the composites. The original contribution of this paper states that samples post-cured in microwaves have higher dielectric constant values but lower loss tangent values than their counterparts post-cured in an oven. For all percentages by weight of sawdust, the glass transition temperature for the microwave-cured samples was lower and the composite was softer; the opposite was true for the oven-cured sample. In addition, the storage modulus of all samples post-cured in microwaves is also lower than their counterparts. This is in line with the fact that it is a softer material and has lower storage modulus and lower glass transition temperature.

Uncertainty Estimation in Simultaneous Measurements of Levels and Permittivities of Liquids Using TDR Technique

Time-domain reflectometry (TDR) based on instruments are commonly used for several monitoring methods, particularly in soil moisture and volumetric water-content evaluation. Furthermore, significant advantages of TDR methodology, mostly related to the possible determination in real-time and to a nondestructive approach of the spatial location and nature of various objects, make this technique an appealing candidate for a variety of environmental and industrial applications. In this paper, we show that the suitable combination of TDR-detecting functionalities can lead to a joint quantitative and qualitative monitoring method for liquid-control purposes, so that, in one shot, the analysis of TDR data allow the measurement of liquid levels, the determination of multiple interfaces in layered media, as well as the evaluation of dielectric properties, thus opening challenging perspectives for several monitoring applications, particularly in fluid-processing-related industry. For such purposes, a detailed analysis of the uncertainty of the proposed measurement method is mandatory; hence, a metrological characterization of the method is carried out, demonstrating that the presented technique is definitely valid for simultaneously measuring levels and dielectric constants of liquids, with uncertainties under 2%. Results obtained for different liquid samples validate the approach on a wide range of dielectric materials and demonstrate the robustness and reliability of the proposed TDR technique.

Evaluation of Dielectric Properties of Printed Wiring Board Materials by Using a Microstrip-ring and Strip-line Ring Resonator Methods

In this article, the opportunities to apply microstrip and strip-line ring resonator methods for evaluating the performance of the PWB materials are discussed. The study consists of an evaluation of the effects of frequency, temperature, and moisture absorption on the dielectric properties of the PWB. The study is carried out mainly in the frequency range from 1 GHz to 10 GHZ that includes ally typical electronic and wireless consumer products. An experimental research for the study is carried out mainly using different FR-4 type materials due to the principal use of FR-4 in mass production

Simultaneous measurement of dielectric properties and levels of liquids using a TDR method

Several monitoring methods, in the recent years, involved microwave/radio frequency (RF) reflectometry techniques, particularly in remote sensing, environmental and industrial application fields. The main advantages using reflectometry are due to its relevant performance characteristics, in terms of high flexibility, high sensitivity and large application conditions. Furthermore, the time domain reflectometry (TDR) presents some attractive advantages, related to the possible determination of the spatial location and nature of various objects, in real-time and with a non-destructive approach. This makes the TDR technique an appealing candidate for a variety of environmental and industrial applications. Although TDR instruments are commonly used today, particularly for the above mentioned purposes, the state of the art is rather lacking in liquid monitoring applications. In this paper we demonstrate that a suitable combination of TDR detecting functionalities, in terms of spatial localization, dielectric properties estimation and coaxial probe performance characteristics, leads to an enhanced quantitative and qualitative monitoring method. Really, in one shot, the analysis of TDR data allows the measurement of liquid levels, the determination of multiple interfaces in layered media, as well as the evaluation of dielectric properties, such as dielectric permittivity or electrical conductivity. Moreover, some applications to real cases are proposed, referred to petrol–chemical mixtures or water-based liquids, thus validating the approach on a wide range of materials.

Dielectric properties of nano-crystalline BaTiO 3 synthesized by micro-emulsion method

Ferroelectricity of the thin films consisting of nano-crystalline BaTiO 3 by micro-emulsion (ME) method was investigated. Ultra-fine BaTiO 3 particle of 8 nm in diameter was obtained. A clear solution of the well-dispersed powder was spin-coated on Si/SiO 2/Al 2O 3/Pt substrate. The crystallinity and particle size were changed with post-annealing from 600 to 1000 °C. Dielectric properties of the films were measured as a function of biasing field, frequency and temperature. It was revealed from the evaluation of dielectric properties and microstructure that annealing at higher than 700 °C provided BaTiO 3 thin film with ferroelectricity. Typical ferroelectric D–E hysteresis was observed with thin films of 360 nm thick fired at 700 °C. The ceramic consists of the fine-grains of 18 nm in diameter. Dielectric constant and dissipation factor were 770 and 2.4%, respectively. The grain growth was taken place with elevating the heating temperature. But the grain growth was not as serious as expected. The sample fired at 1000 °C had still fine grain size of 67 nm. The insulation resistance was higher than 109 Ω cm, which is an acceptable vale for capacitor applications.

Theoretical evaluation of dielectric absorption of microwave energy at the scale of nucleic acids.

A theoretical model is proposed for the evaluation of dielectric properties of the cell nucleus between 0.3 and 3 GHz, as a function of its nucleic acids (NA) concentration (CNA). It is based on literature data on dielectric properties of DNA solutions and nucleoplasm. In skeletal muscle cells, the specific absorption rate (SAR) ratio between nucleoplasm and cytoplasm is found to be larger than one for CNA above 30 mg/ml. A nearly linear relationship is found between CNA and this nucleocytoplasmic SAR ratio. Considering the nanoscale of the layer of condensed counterions and bound water molecules at the NA-solution interface, the power absorption per unit volume is evaluated at this precise location. It is found to be between one and two orders of magnitude above that in muscle tissue as a whole. Under realistic microwave (MW) exposure conditions, however, these SAR inhomogeneities do not generate any significant thermal gradient at the scale considered here. Nevertheless, the question arises of a possible biological relevance of nonnegligible and preferential heat production at the location of the cell nucleus and of the NA molecules.

New approach for open resonator analysis for dielectric measurements at mm-wavelengths

Impedance transformation theory has been applied in order to describe a spherical Fabry-Perot resonator with monolithic dielectric samples at different positions along the resonator axis. The information due to different sample positioning in the resonator allows increasing accuracy in the evaluation of dielectric properties. Low loss materials like CVD-diamonds were taken as test specimens. The formalism can be extended to the case of sequences of dielectric layers. Experimental and modelling results are presented for two cases of sample geometry: resonant and anti-resonant. As an example the influence of additional surface loss on resonator parameters is quantified.