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A special issue of Sensors (ISSN 1424-8220). This special issue belongs to the section "Physical Sensors".

Deadline for manuscript submissions: closed (20 February 2022) | Viewed by 25610

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Dr. Ahmet Can Sabuncu

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Guest Editor

Worcester Polytechnic Institute, Worcester, MA, 01609
Interests: Dielectric Spectroscopy of Cells and Tissues, Dielectric Relaxation Models and Computer Simulation of Dielectric Response, Thermal and Fluidic Engineering, Aero and hydro acoustics, Novel Teaching Techniques: Teaching for Entrepreneurial Mindset Learning, Vygotsky Cycle for Engineering Design Education

Special Issue Information

Dear Colleagues,

We cordially invite you to conribute to the special issue on dielectric spectroscopy sensors. Since its inception over 100 years ago, dielectric spectroscopy has found numerous applications from biomedical sciences to material science. Developing sensor systems for unmet needs in engineering sciences and understanding the polarization of materials to deduce dielectric relaxation mechanisms are compelling problems for many investigators.

We solicit original research papers and review articles in the special issue. This special issue aims to highlight the recent advances in the theory and the practice of dielectric spectroscopy. The topics include, but they are not limited to,

Dielectric spectroscopy of interfaces, complex materials, (bio)macromolecules, lipid vesicles, cell suspensions, and tissues. Applications in biomedical science, agriculture, and material science. Applications in fields such as cancer diagnosis, wearable biometric sensors and others. Novel applications of DS are considered.
Dielectric relaxation models for cells, tissues, and for other composite materials, solutions, suspensions. Computer simulations of dielectric response of materials. Theoretical advancements. Treatise of complex and multiscale problems, such as dielectric response of aggregating blood, cells connected with gap junctions, and low frequency (alpha) dispersion.
Studies at the interface of DS and microfluidic technologies. Use of DS to determine the dielectrophoretic response of cells: Measurement of Clausius-Mossotti factor of cells and biomacromolecules. Studies that investigate single cell dielectric cytometer designs. Other miniaturized impedance-based sensor systems.
Measurement systems for dielectric spectroscopy. Use of integrated circuits for multi-frequency impedance measurements. Analog front ends for such circuits. Resonant circuits.
Measurements at the microwave range, biomedical imaging with impedance measurements, measurements with arrays of electrodes, impedance tomography techniques.

Dr. Ahmet Can Sabuncu
Guest Editor

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Keywords

dielectric spectroscopy
bioimpedance sensors
dielectric relaxation
impedance imaging

Published Papers (7 papers)

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Research

15 pages, 7801 KiB

Open AccessArticle

Experimental Verification of Dielectric Models with a Capacitive Wheatstone Bridge Biosensor for Living Cells: E. coli

by Faezeh Zarrinkhat, Luís Jofre-Roca, Marc Jofre, Juan M. Rius and Jordi Romeu

Sensors 2022, 22(7), 2441; https://doi.org/10.3390/s22072441 - 22 Mar 2022

Cited by 4 | Viewed by 2228

Abstract

Detection of bioparticles is of great importance in electrophoresis, identification of biomass sources, food and water safety, and other areas. It requires a proper model to describe bioparticles’ electromagnetic characteristics. A numerical study of Escherichia coli bacteria during their functional activity was carried out by using two different geometrical models for the cells that considered the bacteria as layered ellipsoids and layered spheres. It was concluded that during cell duplication, the change in the dielectric permittivity of the cell is high enough to be measured at radio frequencies of the order of 50 kHz. An experimental setup based on the capacitive Wheatstone bridge was designed to measure relative changes in permittivity during cell division. In this way, the theoretical model was validated by measuring the dielectric permittivity changes in a cell culture of Escherichia coli ATTC 8739 from WDCM 00012 Vitroids. The spheroidal model was confirmed to be more accurate. Full article

(This article belongs to the Special Issue Dielectric Spectroscopy Sensors)

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13 pages, 2806 KiB

Open AccessArticle

Dielectric Dispersion Modulated Sensing of Yeast Suspension Electroporation

by Guilherme B. Pintarelli, Jessica R. da Silva, Wuqiang Yang and Daniela O. H. Suzuki

Sensors 2022, 22(5), 1811; https://doi.org/10.3390/s22051811 - 25 Feb 2022

Cited by 4 | Viewed by 2131

Abstract

A specific pulsed electric field protocol can be used to induce electroporation. This is used in the food industry for yeast pasteurization, in laboratories for generic transfer and the medical field for cancer treatment. The sensing of electroporation can be done with simple ‘instantaneous’ voltage-current analysis. However, there are some intrinsic low-frequency phenomena superposing the electroporation current, such as electrode polarization. The biological media are non-homogeneous, giving them specific characterization in the broad frequency spectrum. For example, the cell barrier, i.e., cell membrane, causes so called β-dispersion in the frequency range of tens to thousands of kHz. Electroporation is a dynamic phenomenon characterized by altering the cell membrane permeability. In this work, we show that the impedance measurement at certain frequencies could be used to detect the occurrence of electroporation, i.e., dielectric dispersion modulated sensing. This approach may be used for the design and implementation of electroporation systems. Yeast suspension electroporation is simulated to show changes in the frequency spectrum. Moreover, the alteration depends on characteristics of the system. Three types of external buffers and their characteristics are evaluated. Full article

(This article belongs to the Special Issue Dielectric Spectroscopy Sensors)

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11 pages, 1993 KiB

Open AccessArticle

A Microfluidic Dielectric Spectroscopy System for Characterization of Biological Cells in Physiological Media

by Shide Bakhtiari, Mohammad K. D. Manshadi, Amin Mansoorifar and Ali Beskok

Sensors 2022, 22(2), 463; https://doi.org/10.3390/s22020463 - 8 Jan 2022

Cited by 4 | Viewed by 2519

Abstract

Dielectric spectroscopy (DS) is a promising cell screening method that can be used for diagnostic and drug discovery purposes. The primary challenge of using DS in physiological buffers is the electrode polarization (EP) that overwhelms the impedance signal within a large frequency range. These effects further amplify with the miniaturization of the measurement electrodes. In this study, we present a microfluidic system and the associated equivalent circuit models for real-time measurements of cell membrane capacitance and cytoplasm resistance in physiological buffers with 10 s increments. The current device captures several hundreds of biological cells in individual microwells through gravitational settling and measures the system’s impedance using microelectrodes covered with dendritic gold nanostructures. Using PC-3 cells (a highly metastatic prostate cancer cell line) suspended in cell growth media (CGM), we demonstrate stable measurements of cell membrane capacitance and cytoplasm resistance in the device for over 15 min. We also describe a consistent application of the equivalent circuit model, starting from the reference measurements used to determine the system parameters. The circuit model is tested using devices with varying dimensions, and the obtained cell parameters between different devices are nearly identical. Further analyses of the impedance data have shown that accurate cell membrane capacitance and cytoplasm resistance can be extracted using a limited number of measurements in the 5 MHz to 10 MHz range. This will potentially reduce the timescale required for real-time DS measurements below 1 s. Overall, the new microfluidic device can be used for the dielectric characterization of biological cells in physiological buffers for various cell screening applications. Full article

(This article belongs to the Special Issue Dielectric Spectroscopy Sensors)

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17 pages, 4756 KiB

Open AccessArticle

Interdigitated Electrode for Electrical Characterization of Commercial Pseudo-Binary Biodiesel–Diesel Blends

by Inocêncio Sanches dos Santos-Neto, Christian Diniz Carvalho, Gilberto Balby Araújo Filho, Cassio Daniel Salomão Silva Andrade, Giselle Cutrim de Oliveira Santos, Allan Kardec Barros, João Viana da Fonseca Neto, Vicente Leonardo Paucar Casas, Luciana Magalhães Rebelo Alencar, Alberto Jorge Oliveira Lopes, Fernando Carvalho Silva and Francisco Sávio Mendes Sinfrônio

Sensors 2021, 21(21), 7288; https://doi.org/10.3390/s21217288 - 1 Nov 2021

Cited by 11 | Viewed by 8302

Abstract

Non-standard diesel blends can be harmful to the environment and human health. In this context, a simple analytical method to estimate the biodiesel mixture ratio in diesel was developed based on impedance spectroscopy (IS) associated with interdigitated sensors. In this article, four different interdigitated sensors with varied comb spacing (G) were simulated using the COMSOL Multiphysics software. Based on finite element simulations, four interdigitated electrode architectures were manufactured and evaluated. The best geometry was chosen according to theoretical data simulations, and its interdigitated electrodes were manufactured for the compositional evaluation of pseudo-binary biodiesel–diesel mixtures. According to the X-ray powder diffraction technique, the deposition of the conductive layer (Au⁰) over the surface of the dielectric substrate (SiO₂) did not alter its phase composition. In the analysis of AFM and SEM, it was possible to observe irregular edges on the electrodes, possibly related to the manufacturing process of the thin layers and mechanical stability. Another characteristic observed in the AFM images was the height of the step of the gold layer of the sensor. Several cross sections were obtained, and the mean step value was 225.71 ± 0.0032 nm. Although there were differences in the roughness, the whole sensor had nanometric roughness. Based on the finite element method simulation performed, it can be assumed that the geometric parameters more suitable for the manufacturing of the electrode are W = 20 µm, L = 1000 µm, G = 50 µm, and N = 40 digits. The electrical characterization performed by impedance spectroscopy showed that we could differentiate between biodiesel and diesel fuels and their pseudo-binary mixtures in the low-frequency region. Full article

(This article belongs to the Special Issue Dielectric Spectroscopy Sensors)

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15 pages, 4224 KiB

Open AccessArticle

New Sensor to Measure the Microencapsulated Active Compounds Released in an Aqueous Liquid Media Based in Dielectric Properties in Radiofrequency Range

by Juan Angel Tomas-Egea, Pedro J. Fito, Ricardo J. Colom and Marta Castro-Giraldez

Sensors 2021, 21(17), 5781; https://doi.org/10.3390/s21175781 - 27 Aug 2021

Viewed by 1683

Abstract

In recent years, the general and scientific interest in nutrition, digestion, and what role they play in our body has increased, and there is still much work to be carried out in the field of developing sensors and techniques that are capable of identifying and quantifying the chemical species involved in these processes. Iron deficiency is the most common and widespread nutritional disorder that mainly affects the health of children and women. Iron from the diet may be available as heme or organic iron, or as non-heme or inorganic iron. The absorption of non-heme iron requires its solubilization and reduction in the ferric state to ferrous that begins in the gastric acid environment, because iron in the ferric state is very poorly absorbable. There are chemical species with reducing capacity (antioxidants) that also have the ability to reduce iron, such as ascorbic acid. This paper aims to develop a sensor for measuring the release of encapsulated active compounds, in different media, based on dielectric properties measurement in the radio frequency range. An impedance sensor able to measure the release of microencapsulated active compounds was developed. The sensor was tested with calcium alginate beads encapsulating iron ions and ascorbic acid as active compounds. The prediction and measurement potential of this sensor was improved by developing a thermodynamic model that allows obtaining kinetic parameters that will allow suitable encapsulation design for subsequent release. Full article

(This article belongs to the Special Issue Dielectric Spectroscopy Sensors)

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15 pages, 1367 KiB

Open AccessArticle

Modeling Stratum Corneum Swelling for the Optimization of Electrode-Based Skin Hydration Sensors

by Claudio Malnati, Daniel Fehr, Fabrizio Spano and Mathias Bonmarin

Sensors 2021, 21(12), 3986; https://doi.org/10.3390/s21123986 - 9 Jun 2021

Viewed by 4903

Abstract

We present a novel computational model of the human skin designed to investigate dielectric spectroscopy electrodes for stratum corneum hydration monitoring. The multilayer skin model allows for the swelling of the stratum corneum, as well as the variations of the dielectric properties under several hydration levels. According to the results, the stratum corneum thickness variations should not be neglected. For high hydration levels, swelling reduces the skin capacitance in comparison to a fixed stratum corneum thickness model. In addition, different fringing-field electrodes are evaluated in terms of sensitivity to the stratum corneum hydration level. As expected, both conductance and capacitance types of electrodes are influenced by the electrode geometry and dimension. However, the sensitivity of the conductance electrodes is more affected by dimension changes than the capacitance electrode leading to potential design optimization. Full article

(This article belongs to the Special Issue Dielectric Spectroscopy Sensors)

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24 pages, 2028 KiB

Open AccessArticle

Dielectric Spectroscopy Based Detection of Specific and Nonspecific Cellular Mechanisms

by Michael R. Stoneman and Valerică Raicu

Sensors 2021, 21(9), 3177; https://doi.org/10.3390/s21093177 - 3 May 2021

Cited by 3 | Viewed by 2514

Abstract

Using radiofrequency dielectric spectroscopy, we have investigated the impact of the interaction between a G protein-coupled receptor (GPCR), the sterile2 α-factor receptor protein (Ste2), and its cognate agonist ligand, the α-factor pheromone, on the dielectric properties of the plasma membrane in living yeast cells (Saccharomyces cerevisiae). The dielectric properties of a cell suspension containing a saturating concentration of α-factor were measured over the frequency range 40Hz–110 MHz and compared to the behavior of a similarly prepared suspension of cells in the absence of α-factor. A spherical three-shell model was used to determine the electrical phase parameters for the yeast cells in both types of suspensions. The relative permittivity of the plasma membrane showed a significant increase after exposure to α-factor (by 0.06

\pm

0.05). The equivalent experiment performed on yeast cells lacking the ability to express Ste2 showed no change in plasma membrane permittivity. Interestingly, a large change also occurred to the electrical properties of the cellular interior after the addition of α-factor to the cell suspending medium, whether or not the cells were expressing Ste2. We present a number of different complementary experiments performed on the yeast to support these dielectric data and interpret the results in terms of specific cellular reactions to the presence of α-factor. Full article

(This article belongs to the Special Issue Dielectric Spectroscopy Sensors)

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