scholarly journals Towards Accurate Microwave Characterization of Tissues: Sensing Depth Analysis of Open-Ended Coaxial Probes with Ex Vivo Rat Breast and Skin Tissues

Diagnostics ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 338
Author(s):  
Cemanur Aydinalp ◽  
Sulayman Joof ◽  
Tuba Yilmaz
Keyword(s):  
Dielectric Properties ◽  
Dielectric Property ◽  
Classification Accuracy ◽  
Ex Vivo ◽  
Error Source ◽  
Aperture Diameter ◽  
Depth Analysis ◽  
Coaxial Probes ◽  
Measurement Results ◽  
Destructive Measurement

Dielectric properties of biological materials are commonly characterized with open-ended coaxial probes due to the broadband and non-destructive measurement capabilities. Recently, potential diagnostics applications of the technique have been investigated. Although the technique can successfully classify the tissues with different dielectric properties, the classification accuracy can be improved for tissues with similar dielectric properties. Increase in classification accuracy can be achieved by addressing the error sources. One well-known error source contributing to low measurement accuracy is tissue heterogeneity. To mitigate this error source, there is a need define the probe sensing depth. Such knowledge can enable application-specific probe selection or design. The sensing depth can also be used as an input to the classification algorithms which can potentially improve the tissue classification accuracy. Towards this goal, this work investigates the sensing depth of a commercially available 2.2 mm aperture diameter probe with double-layered configurations using ex vivo rat breast and skin tissues. It was concluded that the dielectric property contrast between the heterogeneous tissue components has an effect on the sensing depth. Also, a membrane layer (between 0.4–0.8 mm thickness) on the rat wet skin tissue and breast tissue will potentially affect the dielectric property measurement results by 52% to 84%.

scholarly journals Towards Non-Invasive Diagnosis of Skin Cancer: Sensing Depth Investigation of Open-Ended Coaxial Probes

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1319
Author(s):  
Cemanur Aydinalp ◽  
Sulayman Joof ◽  
Tuba Yilmaz
Keyword(s):  
Dielectric Properties ◽  
Dielectric Property ◽  
Measurement Error ◽  
Skin Cancer ◽  
Rapid Change ◽  
Biological Tissues ◽  
Tissue Heterogeneity ◽  
Low Contrast ◽  
Practical Applications ◽  
Coaxial Probes

Dielectric properties of biological tissues are traditionally measured with open-ended coaxial probes. Despite being commercially available for laboratory use, the technique suffers from high measurement error. This prevents the practical applications of the open-ended coaxial probes. One such application is the utilization of the technique for skin cancer detection. To enable a diagnostic tool, there is a need to address the error sources. Among others, tissue heterogeneity is a major contributor to measurement error. The effect of tissue heterogeneity on measurement accuracy can be decreased by quantifying the probe sensing depth. To this end, this work (1) investigates the sensing depth of the 2.2 mm-diameter open-ended coaxial probe for skin mimicking material and (2) offers a simple experimental setup and protocol for sensing depth characterization of open-ended coaxial probes. The sensing depth characterized through simulation and experiments using two double-layered configurations composed to mimic the skin tissue heterogeneity. Three thresholds in percent increase of dielectric property measurements were chosen to determine the sensing depth. Based on the experiment results, it was concluded that the sensing depth was effected by the dielectric property contrast between the layers. That is, high contrast results in rapid change whereas low contrast results in a slower change in measured dielectric properties. It was also concluded that the sensing depth was independent of frequency between 0.5 to 6 GHz and was mostly determined by the material located immediately at the aperture of the probe.

scholarly journals Mechanical and Dielectric Properties of Aligned Electrospun Fibers

Fibers ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 4
Author(s):  
Blesson Isaac ◽  
Robert M. Taylor ◽  
Kenneth Reifsnider
Keyword(s):  
Dielectric Properties ◽  
Dielectric Property ◽  
Electrospun Nanofibers ◽  
Cold Drawing ◽  
General Interest ◽  
Electrospun Fibers ◽  
Energy Storage Devices ◽  
Electrospinning Technique ◽  
Specific Strength ◽  
Aligned Nanofibers

This review paper examines the current state-of-the-art in fabrication of aligned fibers via electrospinning techniques and the effects of these techniques on the mechanical and dielectric properties of electrospun fibers. Molecular orientation, system configuration to align fibers, and post-drawing treatment, like hot/cold drawing process, contribute to better specific strength and specific stiffness properties of nanofibers. The authors suggest that these improved, aligned nanofibers, when applied in composites, have better mechanical and dielectric properties for many structural and multifunctional applications, including advanced aerospace applications and energy storage devices. For these applications, most fiber alignment electrospinning research has focused on either mechanical property improvement or dielectric property improvement alone, but not both simultaneously. Relative to many other nanofiber formation techniques, the electrospinning technique exhibits superior nanofiber formation when considering cost and manufacturing complexity for many situations. Even though the dielectric property of pure nanofiber mat may not be of general interest, the analysis of the combined effect of mechanical and dielectric properties is relevant to the present analysis of improved and aligned nanofibers. A plethora of nanofibers, in particular, polyacrylonitrile (PAN) electrospun nanofibers, are discussed for their mechanical and dielectric properties. In addition, other types of electrospun nanofibers are explored for their mechanical and dielectric properties. An exploratory study by the author demonstrates the relationship between mechanical and dielectric properties for specimens obtained from a rotating mandrel horizontal setup.

Bone permittivity and its effect on using ground-penetrating radar

Geophysics ◽  
2018 ◽  
Vol 83 (1) ◽  
pp. H1-H11
Author(s):  
Blair B. Schneider ◽  
Georgios Tsoflias ◽  
Don W. Steeples ◽  
Rolfe Mandel ◽  
Jack Hofman
Keyword(s):  
Dielectric Properties ◽  
Dielectric Property ◽  
Ground Penetrating Radar ◽  
Relative Permittivity ◽  
Water Saturation ◽  
Mixing Models ◽  
Bone Properties ◽  
Animal Bone ◽  
Bone Minerals ◽  
Ground Penetrating

Ground-penetrating radar (GPR) is a powerful tool that is still being developed for archaeological investigations. We investigated the dielectric properties of mammoth bone and bone from modern bison, cow, deer, and elk as a proxy for applying GPR for detecting prehistoric animal remains. Sample dielectric properties (relative permittivity, loss factor, and loss-tangent values) were measured with an impedance analyzer over frequencies ranging from 10 MHz to 1 GHz. Bone-sample porosity, bulk density, water saturation, and volumetric water content of the specimens were also measured. The measured sample-relative permittivity values were then compared with modeled relative permittivity values using common dielectric-mixing models to determine which parameters control the best-fit predictions of relative permittivity of animal bone. We observe statistically significant dielectric-property differences among different animal fauna, as well as variation as a function of frequency. In addition, we determine that the relative permittivity values of 8–9 for similar minerals, such as apatite, are not suitable as a proxy for predicting animal bone properties. We estimate new relative permittivity values of 3–5 for dry animal bone minerals in the frequency range of 100–1000 MHz using these common dielectric-mixing models. We postulate that differences in bone microstructure contribute to dielectric-property variability.

scholarly journals In-Depth Analysis of the Impact of Different Serum-Free Media on the Production of Clinical Grade Dendritic Cells for Cancer Immunotherapy

2021 ◽  
Vol 11 ◽  
Author(s):  
João Calmeiro ◽  
Luís Mendes ◽  
Iola F. Duarte ◽  
Catarina Leitão ◽  
Adriana R. Tavares ◽  
...  
Keyword(s):  
T Cells ◽  
Nk Cells ◽  
Cancer Immunotherapy ◽  
Ex Vivo ◽  
Culture Conditions ◽  
Clinical Grade ◽  
Serum Free ◽  
Depth Analysis ◽  
Free Media ◽  
The Impact

Dendritic cell (DC)-based antitumor vaccines have proven to be a safe approach, but often fail to generate robust results between trials. Translation to the clinic has been hindered in part by the lack of standard operation procedures for vaccines production, namely the definition of optimal culture conditions during ex-vivo DC differentiation. Here we sought to compare the ability of three clinical grade serum-free media, DendriMACS, AIM-V, and X-VIVO 15, alongside with fetal bovine serum-supplemented Roswell Park Memorial Institute Medium (RPMI), to support the differentiation of monocyte-derived DCs (Mo-DCs). Under these different culture conditions, phenotype, cell metabolomic profiles, response to maturation stimuli, cytokines production, allogenic T cell stimulatory capacity, as well as priming of antigen-specific CD8+ T cells and activation of autologous natural killer (NK) cells were analyzed. Immature Mo-DCs differentiated in AIM-V or X-VIVO 15 presented lower levels of CD1c, CD1a, and higher expression of CD11c, when compared to cells obtained with DendriMACS. Upon stimulation, only AIM-V or X-VIVO 15 DCs acquired a full mature phenotype, which supports their enhanced capacity to polarize T helper cell type 1 subset, to prime antigen-specific CD8+ T cells and to activate NK cells. CD8+ T cells and NK cells resulting from co-culture with AIM-V or X-VIVO 15 DCs also showed superior cytolytic activity. 1H nuclear magnetic resonance-based metabolomic analysis revealed that superior DC immunostimulatory capacities correlate with an enhanced catabolism of amino acids and glucose. Overall, our data highlight the impact of critically defining the culture medium used in the production of DCs for clinical application in cancer immunotherapy. Moreover, the manipulation of metabolic state during differentiation could be envisaged as a strategy to enhance desired cell characteristics.

A study of the dielectric properties of biological tissues: Ex-vivo vs preserved samples

2017 ◽  
Author(s):  
Irina L. Alborova ◽  
Julian Bonello ◽  
Lourdes Farrugia ◽  
Charles V. Sammut ◽  
Lesya N. Anishchenko
Keyword(s):  
Dielectric Properties ◽  
Ex Vivo ◽  
Biological Tissues

Characterization of Dielectric Properties of Alkoxy-Derived (Y,Yb)MnO3 Ferroelectrics/Insulator Stacking Layers

2006 ◽  
Vol 301 ◽  
pp. 65-70 ◽  
Author(s):  
Kazuyuki Suzuki ◽  
Kiyotaka Tanaka ◽  
Tatsuo Kimura ◽  
Kaori Nishizawa ◽  
Takeshi Miki ◽  
...  
Keyword(s):  
Thin Films ◽  
Dielectric Properties ◽  
Dielectric Property ◽  
Surface Morphology ◽  
Insulator Layer ◽  
Surface Smoothness ◽  
Y2o3 Layer ◽  
Mno3 Film ◽  
Mfis Structure

The (Y,Yb)MnO3 films were crystallized on Y2O3 layers using alkoxy-derived precursor solutions. As a result of investigation of the effect of the Y2O3 layer on the dielectric properties of the (Y,Yb)MnO3/Y2O3/Si, the crystallographic properties such as the orientation and surface morphology of the (Y,Yb)MnO3 thin films depended on the crystallographic appearance of the insulator layer. Following that, the dielectric properties of the MFIS structures varied. For the construction of excellent MFIS structure, the improvement of the orientation, crystallinity, and surface smoothness of the (Y,Yb)MnO3 film by the optimization of the microstructure and dielectric property of the insulator is necessary.

scholarly journals Exploiting Tissue Dielectric Properties to Shape Microwave Thermal Ablation Zones

Sensors ◽  
2020 ◽  
Vol 20 (14) ◽  
pp. 3960
Author(s):  
Anna Bottiglieri ◽  
Giuseppe Ruvio ◽  
Martin O’Halloran ◽  
Laura Farina
Keyword(s):  
Adipose Tissue ◽  
Dielectric Properties ◽  
Thermal Ablation ◽  
Ex Vivo ◽  
Reference Scenario ◽  
Target Tissue ◽  
Ablation Zone ◽  
Dielectric Characterization ◽  
Clinical Scenarios ◽  
Tissue Target

The dielectric characterization of tissue targets of microwave thermal ablation (MTA) have improved the efficacy and pre-procedural planning of treatment. In some clinical scenarios, the tissue target lies at the interface with an external layer of fat. The aim of this work is to investigate the influence of the dielectric contrast between fat and target tissue on the shape and size of the ablation zone. A 2.45 GHz monopole antenna is placed parallel to an interface modelled by fat and a tissue characterized by higher dielectric properties and powered at 30 and 60 W for 60 s. The performances of MTA are numerically investigated considering different interface scenarios (i.e., different widths of fat layer, shifts in the antenna alignment) and a homogeneous reference scenario. Experiments (N = 10) are conducted on ex vivo porcine tissue to validate the numerical results. Asymmetric heating patterns are obtained in the interface scenario, the ablation zone in the target tissue is two-fold to ten-fold the size of the zone in the adipose tissue, and up to four times larger than the homogenous scenario. The adipose tissue reflects the electromagnetic energy into the adjacent tissue target, reducing the heating in the opposite direction.

Structure property relationships in core-shell BaTiO3–LiF ceramics

1993 ◽  
Vol 8 (4) ◽  
pp. 871-879 ◽  
Author(s):  
C.A. Randall ◽  
S.F. Wang ◽  
D. Laubscher ◽  
J.P. Dougherty ◽  
W. Huebner
Keyword(s):  
Experimental Data ◽  
Dielectric Properties ◽  
Dielectric Property ◽  
Potential Application ◽  
Microstructural Development ◽  
Core Shell ◽  
Structure Property ◽  
The Core ◽  
Structure Property Relationships ◽  
Multilayer Capacitors

A sintering, microstructural development and dielectric property study of BaTiO3–LiF ceramics was performed to assess the potential application of low-fired multilayer capacitors. Not only does LiF allow for sintering below 1000 °C, it also allows for the manipulation of dielectric properties and interfaces within BaTiO3–LiF ceramics. Using mixing laws, a model of the dielectric properties of the core-shell microstructures is presented that agrees well with the observed experimental data.

Dielectric Property of Cyanate Ester / Nano-TiO2 Particles or TiO2 Whiskers Encapsulated by Polyaniline

2007 ◽  
Vol 334-335 ◽  
pp. 845-848
Author(s):  
Jie Tao ◽  
Hui Zhou ◽  
Qi Qin ◽  
Yi Hua Cui
Keyword(s):  
Dielectric Properties ◽  
Dielectric Property ◽  
Dielectric Loss ◽  
Cyanate Ester ◽  
Nano Tio2 ◽  
Tio2 Particles ◽  
Mixing Method

Nano-TiO2 particles or TiO2 whiskers encapsulated by polyaniline/cyanate ester composites were fabricated by solution-mixing method. Then the dispersion of particles in cyanate ester was observed with the aid of TEM. The effect of the content of particles or whiskers on the dielectric properties of cyanate ester composites was investigated. As the content of the particles up to 3% or the whiskers up to 7%, the dielectric loss of the composites achieved its maximum.

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