Application of a Coaxial-Like Sensor for Impedance Spectroscopy Measurements of Selected Low-Conductivity Liquids

Szypłowska, Agnieszka; Nakonieczna, Anna; Wilczek, Andrzej; Paszkowski, Bartosz; Solecki, Grzegorz; Skierucha, Wojciech

doi:10.3390/s131013301

Cited by 22 publications

(10 citation statements)

References 30 publications

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“…These results are in good agreement with those showed in Figure 2 , at low frequencies. Several researches have reported a similar behavior [ 9 , 10 , 12 – 14 ], where the constant phase is explained by the creation of a strong electric field on the alignment layers. Therefore, a constant phase element (CPE) has been included to model the phenomenon.…”

Section: Electrical Equivalent Circuit Proposalmentioning

confidence: 75%

Frequency and Temperature Dependence of Fabrication Parameters in Polymer Dispersed Liquid Crystal Devices

et al. 2014

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A series of polymer dispersed liquid crystal devices using glass substrates have been fabricated and investigated focusing on their electrical properties. The devices have been studied in terms of impedance as a function of frequency. An electric equivalent circuit has been proposed, including the influence of the temperature on the elements into it. In addition, a relevant effect of temperature on electrical measurements has been observed.

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Section: Electrical Equivalent Circuit Proposalmentioning

confidence: 75%

Frequency and Temperature Dependence of Fabrication Parameters in Polymer Dispersed Liquid Crystal Devices

et al. 2014

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“…The system, shown in Figure 1a, is characterized by small size (11 cm × 15 cm × 5 cm), light weight (350 g), quick measurement response (30 s) and can be powered by a USB port or batteries (3 AAA alkaline batteries). The system measurement working principle is based on electrical impedance spectroscopy (EIS) [24], a popular technique used in different fields of application, such as bacterial concentration detection [25,26], food quality screening [27,28], human body analysis [29,30], detection of chemical compounds [31][32][33] and measurement of the corrosion rate of metallic structures in direct contact with acid electrolytes [34,35].…”

Section: Portable Sensor Systemmentioning

confidence: 99%

A Portable Battery-Operated Sensor System for Simple and Rapid Assessment of Virgin Olive Oil Quality Grade

et al. 2022

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Virgin olive oil quality is assessed by chemical as well as sensory analysis. Two of the most important parameters that define the quality of virgin olive oils are the free acidity and the peroxide index. These chemical parameters are usually determined by manual titration procedures that must be carried out in a laboratory by trained personnel. In this paper, a portable sensor system to support the quality grade assessment of virgin olive oil is presented. The system is battery operated and characterized by small dimensions, light weight and quick measurement response (about 30 s). The working principle is based on the measurement of the electrical conductance of an emulsion between a chemical reagent and the olive oil sample. Two different chemical reagents have been investigated: (1) a hydro-alcoholic solution (HAS), made of 60% ethanol and 40% distilled water; (2) 100% distilled water (DW). Tests have been carried out on a set of 40 olive oil samples. The results have shown how, for most of the fresh virgin olive oil samples (31 samples out of 40), the free acidity can be estimated with good accuracy from the electrical conductance of the emulsion using HAS as the reagent. In the case of the full set of samples, the emulsion electrical conductance, using HAS as the reagent, is a function of both the sample free acidity as well as the compounds produced by oil oxidation, and a compensation method based on the measured electrical conductance, using DW as the reagent, has been introduced to improve the accuracy in the estimated free acidity. Tests have also been carried out on the full set of samples, using a k-nearest neighbors algorithm, to demonstrate the feasibility of olive oil classification according to the quality grade. The results have shown how measurements carried out using only the HAS reagent provide better classification accuracy than measurements carried out using both the HAS and DW reagents. The proposed system can be a low-cost alternative to standard laboratory analyses to evaluate the quality grade of virgin olive oil.

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“…Direct determination of these properties of agricultural products is either difficult, laborious, expensive, or destructive to the samples [ 2 ]. Dielectric measurements that can be performed using a variety of time- and frequency-domain techniques proved to be fast, relatively inexpensive in comparison to chemical analyses, easily adaptable to automatic monitoring applications, and non-destructive or minimally invasive to the tested material [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. Especially, water content is an example of a vital property that is easily measured using dielectric sensors [ 4 , 6 , 11 ].…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Apple Maturity with Two Types of Dielectric Probes

Kafarski

Wilczek

Szypłowska

et al. 2018

Sensors

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The observed dielectric spectrum of ripe apples in the last period of shelf-life was analyzed using a multipole dielectric relaxation model, which assumes three active relaxation processes: primary α-process (water relaxation) and two secondary processes caused by solid-water-ion interactions α’ (bound water relaxations), as well as β’ (Maxwell-Wagner effect). The performance of two designs of the dielectric probe was compared: a classical coaxial open-ended probe (OE probe) and an open-ended probe with a prolonged central conductor in a form of an antenna (OE-A-probe). The OE-A probe increases the measurement volume and consequently extends the range of applications to other materials, like granulated agricultural products, soils, or liquid suspensions. However, its measurement frequency range is limited as compared to the OE probe because, above 1.5 GHz, the probe with the antenna generates higher propagation modes and the applied calibrations and calculations are not sufficient. It was shown that data from measurements using the OE-A probe gave slightly stronger correlations with apples’ quality parameters than using the typical OE probe. Additionally, we have compared twelve multipole fitting models with different combinations of poles (eight three-pole and four two-pole models). It was shown that the best fit is obtained using a two-pole model for data collected for the OE-A probe and a three-pole model for the OE probe, using only Cole-Cole poles in both cases.

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Application of a Coaxial-Like Sensor for Impedance Spectroscopy Measurements of Selected Low-Conductivity Liquids

Cited by 22 publications

References 30 publications

Frequency and Temperature Dependence of Fabrication Parameters in Polymer Dispersed Liquid Crystal Devices

Frequency and Temperature Dependence of Fabrication Parameters in Polymer Dispersed Liquid Crystal Devices

A Portable Battery-Operated Sensor System for Simple and Rapid Assessment of Virgin Olive Oil Quality Grade

Evaluation of Apple Maturity with Two Types of Dielectric Probes

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