Electrical impedance spectroscopy of plant cells in aqueous buffer media over a wide frequency range of 4 Hz to 20 GHz

The physicochemical characterization of pharmaceutical materials is essential for drug discovery, development and evaluation, and for understanding and predicting their interaction with physiological systems. Amongst many measurement techniques for spectroscopic characterization of pharmaceutical materials, Electrical Impedance Spectroscopy (EIS) is powerful as it can be used to model the electrical properties of pure substances and compounds in correlation with specific chemical composition. In particular, the accurate measurement of specific properties of drugs is important for evaluating physiological interaction. The electrochemical modelling of compounds is usually carried out using spectral impedance data over a wide frequency range, to fit a predetermined model of an equivalent electrochemical cell. This paper presents experimental results by EIS analysis of four drug formulations (trimethoprim/sulfamethoxazole C14H18N4O3-C10H11N3O3, ambroxol C13H18Br2N2O.HCl, metamizole sodium C13H16N3NaO4S, and ranitidine C13H22N4O3S.HCl). A wide frequency range from 20 Hz to 30 MHz is used to evaluate system identification techniques using EIS data and to obtain process models. The results suggest that arrays of linear R-C models derived using system identification techniques in the frequency domain can be used to identify different compounds.

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Design of Reconfigurable Time-to-Digital Converter Based on Cascaded Time Interpolators for Electrical Impedance Spectroscopy

Sensors ◽

10.3390/s20071889 ◽

2020 ◽

Vol 20 (7) ◽

pp. 1889

Author(s):

Sounghun Shin ◽

Yoontae Jung ◽

Soon-Jae Kweon ◽

Eunseok Lee ◽

Jeong-Ho Park ◽

...

Keyword(s):

Impedance Spectroscopy ◽

High Frequency ◽

Electrical Impedance ◽

Phase Error ◽

Electrical Impedance Spectroscopy ◽

Time Range ◽

Digital Converter ◽

Frequency Range ◽

Input Time ◽

Interpolation Factor

This paper presents a reconfigurable time-to-digital converter (TDC) used to quantize the phase of the impedance in electrical impedance spectroscopy (EIS). The TDC in the EIS system must handle a wide input-time range for analysis in the low-frequency range and have a high resolution for analysis in the high-frequency range. The proposed TDC adopts a coarse counter to support a wide input-time range and cascaded time interpolators to improve the time resolution in the high-frequency analysis without increasing the counting clock speed. When the same large interpolation factor is adopted, the cascaded time interpolators have shorter measurement time and smaller chip area than a single-stage time interpolator. A reconfigurable time interpolation factor is adopted to maintain the phase resolution with reasonable measurement time. The fabricated TDC has a peak-to-peak phase error of less than 0.72° over the input frequency range from 1 kHz to 512 kHz and the phase error of less than 2.70° when the range is extended to 2.048 MHz, which demonstrates a competitive performance when compared with previously reported designs.

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Fish quality investigations using electrical impedance spectroscopy: preliminary results

Journal of Physics Conference Series ◽

10.1088/1742-6596/2008/1/012008 ◽

2021 ◽

Vol 2008 (1) ◽

pp. 012008

Author(s):

L G Teixeira ◽

P Bertemes-Filho ◽

M. Keith Cox

Keyword(s):

Quality Control ◽

Impedance Spectroscopy ◽

Predictive Models ◽

Oreochromis Niloticus ◽

Electrical Impedance ◽

Electrical Impedance Spectroscopy ◽

Frequency Range ◽

Long Period ◽

Capacitive Reactance ◽

Over Time

Abstract The consumption of seafood has increased over the last 10 years. This article analyses impedance changes of tilapia (Oreochromis niloticus) sample measured over 36 hours by using electrical impedance spectroscopy (EIS). It was also investigated the correlations between variables in order to predictive models to degradation studies. Measurements were collected every 12 hours in order to verify any change due to deterioration. The results show that measurements in both longitudinal and transverse axes are equivalent and that the sample undergoes gradual variations in the impedance. The first set of data collected in the frequency range from 0.1 to 1,000 kHz showed that resistance varied from 310.9 (@ 0.1 kHz) to 86.8 Ω (@1 MHz) and capacitive reactance varied from -8.6 to 11.5 Ω, respectively. The forth set of data showed a decrease of 79.3% (@0.1 kHz) in the resistance part of the impedance, whereas 98.8% in capacitive reactance at 0.1 kHz. These results might suggest that there was a nutritional loss of the sample over time. Further experiments must be done over a long period of time in order to fully understand the process. EIS might be pointed out as a potential technique for fish shelf live quality control.

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Determination of Leaf Nitrogen Concentrations Using Electrical Impedance Spectroscopy in Multiple Crops

Remote Sensing ◽

10.3390/rs12030566 ◽

2020 ◽

Vol 12 (3) ◽

pp. 566 ◽

Cited By ~ 4

Author(s):

Rinku Basak ◽

Khan Wahid ◽

Anh Dinh

Keyword(s):

Impedance Spectroscopy ◽

Correlation Coefficient ◽

Regression Models ◽

Electrical Impedance ◽

Leaf Nitrogen ◽

Electrical Impedance Spectroscopy ◽

Coefficient Of Determination ◽

Frequency Range ◽

Nitrogen Concentrations

In this work, crop leaf nitrogen concentration (LNC) is predicted by leaf impedance measurements made by electrical impedance spectroscopy (EIS). This method uses portable equipment and is noninvasive, as are other available nondestructive methods, such as hyperspectral imaging, near-infrared spectroscopy, and soil-plant analyses development (SPAD). An EVAL-AD5933EBZ evaluation board is used to measure the impedances of four different crop leaves, i.e., canola, wheat, soybeans, and corn, in the frequency range of 5 to 15 kHz. Multiple linear regression using the least square method is employed to obtain a correlation between leaf nitrogen concentrations and leaf impedances. A strong correlation is found between nitrogen concentrations and measured impedances for multiple features using EIS. The results are obtained by PrimaXL Data Analysis ToolPak and validated by analysis of variance (ANOVA) tests. Optimized regression models are determined by selecting features using the backward elimination method. After a comparative analysis among the four different crops, the best multiple regression results are found for canola with an overall correlation coefficient (R) of 0.99, a coefficient of determination (R2) of 0.98, and root mean square (RMSE) of 0.54% in the frequency range of 8.7–12 kHz. The performance of EIS is also compared with an available SPAD reading which is moderately correlated with LNC. A high correlation coefficient of 0.94, a coefficient of determination of 0.89, and RMSE of 1.12% are obtained using EIS, whereas a maximum correlation coefficient of 0.72, a coefficient of determination of 0.53, and RMSE of 1.52% are obtained using SPAD for the same number of combined observations. The proposed multiple linear regression models based on EIS measurements sensitive to LNC can be used on a very local scale to develop a simple, rapid, inexpensive, and effective instrument for determining the leaf nitrogen concentrations in crops.

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Study of stilbene and resin acid content of Scots pine heartwood by electrical impedance spectroscopy (EIS)

Holzforschung ◽

10.1515/hf.2011.111 ◽

2011 ◽

Vol 65 (5) ◽

Cited By ~ 7

Author(s):

Laura Tomppo ◽

Markku Tiitta ◽

Tapio Laakso ◽

Anni Harju ◽

Martti Venäläinen ◽

...

Keyword(s):

Impedance Spectroscopy ◽

Phase Angle ◽

Scots Pine ◽

Acid Content ◽

Electrical Impedance ◽

Resin Acid ◽

Complex Impedance ◽

Electrical Impedance Spectroscopy ◽

Model Parameters ◽

Frequency Range

Abstract Scots pine (Pinus sylvestris L.) heartwood samples were measured with electrical impedance spectroscopy (EIS) at frequency range 1 Hz–10 MHz in green and relative humidity (RH) 65% conditioned moisture content (MC) after oven-drying. Complex impedance parameters were studied in relation to the density, moisture, resin acid and stilbene contents. The measurements were conducted in tangential (T) and longitudinal (L) directions with 36 samples in each analysis. For green MC, there were significant correlations between impedance phase angle and contents of stilbenes and resin acids at frequencies below 400 Hz. For the resin acid content, the strongest correlation with phase-angleT was -0.45 (P<0.01) at 100 Hz. Impedance magnitude correlated significantly with MC throughout the frequency range, e.g., at 10 kHz, r was -0.71 (P<0.001) for L-direction. In moisture conditioned state, the correlation between stilbenes and T-measured phase angle was strongest at 250 Hz, (r=-0.56, P<0.001). Equivalent circuit model of two ZARC-Cole elements in series was fitted for the measurements in green MC. Several model parameters correlated with MC (e.g., R1, L r=-0.64, P<0.001), but only one parameter correlated weakly with stilbene content (R2, T r=0.35, P<0.05). The study shows that EIS has a potential for independent determination of resin acid or stilbene contents and MC for green pine heartwood.

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Towards optimization of plant cell detection in suspensions using impedance-based analyses and the unified equivalent circuit model

Scientific Reports ◽

10.1038/s41598-021-98901-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kian Kadan-Jamal ◽

Aakash Jog ◽

Marios Sophocleous ◽

Julius Georgiou ◽

Adi Avni ◽

...

Keyword(s):

Impedance Spectroscopy ◽

Equivalent Circuit ◽

Cell Lines ◽

Electrical Impedance ◽

Equivalent Circuit Model ◽

Plant Cells ◽

Circuit Model ◽

Electrical Impedance Spectroscopy ◽

Impedance Spectra

AbstractAn improved approach for comparative study of plant cells for long term and continuous monitoring using electrical impedance spectroscopy is demonstrated for tomato and tobacco plant cells (MSK8 and BY2) in suspensions. This approach is based on the locations and magnitudes of defining features in the impedance spectra of the recently reported unified equivalent circuit model. The ultra-wide range (4 Hz to 20 GHz) impedance spectra of the cell lines were measured using custom probes, and were analyzed using the unified equivalent circuit model, highlighting significant negative phase peaks in the ~ 1 kHz to ~ 10 MHz range. These peaks differ between the tomato and tobacco cells, and since they can be easily defined, they can potentially be used as the signal for differentiating between different cell cultures or monitoring them over time. These findings were further analysed, showing that ratios relating the resistances of the media and the resistance of the cells define the sensitivity of the method, thus affecting its selectivity. It was further shown that cell agglomeration is also an important factor in the impedance modeling in addition to the overall cell concentration. These results can be used for optimizing and calibrating electrical impedance spectroscopy-based sensors for long term monitoring of cell lines in suspension for a given specific cell and media types.

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A Graphical Approach for Human Skin Moisture Evaluation by Electrical Impedance Spectroscopy

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.336-338.319 ◽

2013 ◽

Vol 336-338 ◽

pp. 319-326 ◽

Cited By ~ 4

Author(s):

Yu Xing He ◽

Yong Gui Dong

Keyword(s):

Impedance Spectroscopy ◽

Stratum Corneum ◽

Human Skin ◽

Electrical Impedance ◽

Skin Surface ◽

Electrical Impedance Spectroscopy ◽

Frequency Range ◽

Arc Model ◽

Quantitative Calculation ◽

Skin Moisture

A pair of concentrically placed gold electrodes is utilized in contact with human skin surface for moisture evaluation. The electrical impedance spectroscopy is measured within a frequency range of 100Hz to 5MHz. It is showed that, in case of relatively dried stratum corneum, reproducibility of measured impedances will decrease significantly in lower frequency range. The integrality of impedance frequency locus is correspondingly dependent on skin moist state. On the other hand, in case of relatively wetted stratum corneum, an integral locus can be obtained and Cole-Cole arc model can be applied for quantitative calculation. The integrality of the locus is introduced as a supplemental parameter. Experimental results with moistened filter paper as well as human skin indicate that, the skin moisture can be better represented both graphically and quantitatively.

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