Non-linear dielectric spectroscopy of microbiological suspensions

Treo, Ernesto Federico; Felice, C.J.

doi:10.1186/1475-925x-8-19

Cited by 8 publications

(11 citation statements)

References 42 publications

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“…[6][7][8]. Fortunately, in our previous study, we performed measurements with different cells and obtained relevant results with the three-electrode cell [9]. Our results indicated that the changes in the third harmonic were due to the presence of microorganisms near the EEI [9], where they were consistent with Blake-Coleman's results [10].…”

Section: Introductionsupporting

confidence: 84%

“…Fortunately, in our previous study, we performed measurements with different cells and obtained relevant results with the three-electrode cell [9]. Our results indicated that the changes in the third harmonic were due to the presence of microorganisms near the EEI [9], where they were consistent with Blake-Coleman's results [10]. In all of these studies, it was not indicated whether the changes in the amplitude of the third harmonic originated in changes in the double-layer capacity or in charge transfer resistance.…”

Section: Introductionmentioning

confidence: 99%

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Isoconductivity method to study adhesion of yeast cells to gold electrode

Ruiz

Zamora

Felice

2014

Journal of Electrical Bioimpedance

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In this paper, we used impedance spectroscopy and gold electrodes to detect the presence of yeast cells and monitor the attachment of these cells to the electrodes. We analyzed the effect of conductivity changes of the medium and the attachment on the electrode-electrolyte interface impedance. A three-electrode cell was designed to produce a uniform electric field distribution on the working electrode and to minimize the counter electrode impedance. Moreover, we used a small AC overpotential (10 mV) to keep the system within the linear impedance limits of the electrode-electrolyte interface. This study proposes a new method to differentiate the impedance changes due to the attachment of yeast cells from those due to conductivity changes of the medium. The experiments showed that when the difference between the cell suspension and base solution conductivities is within the experimental error, the impedance changes are only due to the attachment of yeast cells to the electrodes. The experiments also showed a strong dependence (decrease) of the parallel capacity of the electrode electrolyte interface with the yeast cell concentration of suspension. We suggest that this decrease is due to an asymmetrical redistribution of surface charges on both sides of cell, which can be modeled as a biologic capacity connected in series with the double layer capacity of the interface. Our results could help to explain the rate of biofilm formation through the determination of the rate of cell adhesion.

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Section: Introductionsupporting

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Isoconductivity method to study adhesion of yeast cells to gold electrode

Ruiz

Zamora

Felice

2014

Journal of Electrical Bioimpedance

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“…It requires a measurement system with a robust feature to resist artificial and environmental noises, especially in cases of low sample cell concentrations. Among numerous methods, dielectric spectroscopy (DS) based on probes or electrodes has been a common choice for biomass measurement and monitoring due to its advantages of fast, simple, and low-cost features [24,25,26]. However, invasive or contact sensors in these DS systems could lead to serious measurement errors and even contaminate and damage samples under test.…”

Section: Introductionmentioning

confidence: 99%

Magnetic Induction Spectroscopy for Biomass Measurement: A Feasibility Study

Zhang¹,

Roula

Dinsdale

2019

Sensors

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Background: Biomass measurement and monitoring is a challenge in a number of biotechnology processes where fast, inexpensive, and non-contact measurement techniques would be of great benefit. Magnetic induction spectroscopy (MIS) is a novel non-destructive and contactless impedance measurement technique with many potential industrial and biomedical applications. The aim of this paper is to use computer modeling and experimental measurements to prove the suitability of the MIS system developed at the University of South Wales for controlled biomass measurements. Methods: The paper reports experimental measurements conducted on saline solutions and yeast suspensions at different concentrations to test the detection performance of the MIS system. The commercial electromagnetic simulation software CST was used to simulate the measurement outcomes with saline solutions and compare them with those of the actual measurements. We adopted two different ways for yeast suspension preparation to assess the system’s sensitivity and accuracy. Results: For saline solutions, the simulation results agree well with the measurement results, and the MIS system was able to distinguish saline solutions at different concentrations even in the small range of 0–1.6 g/L. For yeast suspensions, regardless of the preparation method, the MIS system can reliably distinguish yeast suspensions with lower concentrations 0–20 g/L. The conductivity spectrum of yeast suspensions present excellent separability between different concentrations and dielectric dispersion property at concentrations higher than 100 g/L. Conclusions: The South Wales MIS system can achieve controlled yeast measurements with high sensitivity and stability, and it shows promising potential applications, with further development, for cell biology research where contactless monitoring of cellular density is of relevance.

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“…Treo and co-workers did measurements with an improved nonlinear dielectric spectrometer and three different electrochemical cells (Treo et al, 2005;Treo and Felice, 2009). One of them was a replica of that used by Woodward and Kell, and the other two were three-and four-electrode cells respectively.…”

Section: Introductionmentioning

confidence: 99%