scholarly journals Effect of anisotropy in myocardial electrical conductivity on lesion characteristics during radiofrequency cardiac ablation: a numerical study

2022 ◽  
Vol 39 (1) ◽  
pp. 120-133
Author(s):  
Kaihao Gu ◽  
Shengjie Yan ◽  
Xiaomei Wu
Keyword(s):  
Electrical Conductivity ◽  
Numerical Study ◽  
Cardiac Ablation

NUMERICAL STUDY OF DIELECTROPHORESIS FORCE IN THE ISOLATED ELECTRODE: A COMPARATIVE APPROACH

2014 ◽  
Vol 26 (05) ◽  
pp. 1450062
Author(s):  
Mazdak Rad Malekshahi ◽  
Karim Ansaroudi ◽  
Hadi Veladi ◽  
Manouchehr Bahrami ◽  
Esmaeil Esmaeilzadeh
Keyword(s):  
Electrical Conductivity ◽  
Electric Field ◽  
Frequency Response ◽  
Dielectric Layer ◽  
Numerical Study ◽  
Particle Separation ◽  
Comparative Approach ◽  
Electrode Arrays ◽  
Pass Filter ◽  
Dielectric Thickness

One of the general methods for particle separation in lab-on-a-chips (LOCs) is dielectrophoresis (DEP). The effects of electrode isolation in DEP-based particle separation devices are discussed throughout this paper. One advantage of the electrode isolation is reducing electrode–electrolyte–sample mutual interactions. In this study, the conventional DEP forces using interdigitated electrode arrays is numerically investigated without and in the presence dielectric layer in the interface of electrode and electrolytic fluid. The study includes the effect of dielectric layer thickness when fluids of different electrical conductivity are involved. The results show that the electric field and also intra-channel gradient of electric field square depend on frequency and an isolating layer acts as high-pass filter, thus frequency response of conventional DEP force besides Clausius–Mossotti (CM) factor is depended on the electric field gradient. The results also show that in contactless model, the frequency response of the DEP forces can be engineered by dielectric thickness and electrical conductivity of the suspending medium. According to the obtained results, during particle separation with DEP method in the presence of insolated electrodes and considering the reduction in electric field intensity, an appropriate and optimal choice for working frequency, voltage of electrodes and thickness of dielectric layer should be considered. The particles and dielectric isolated layer under study is polystyrene beads and polydimethylsiloxane (PDMS) elastomeric polymer, respectively.

scholarly journals A mechanistic model for electrical conduction in soil–root continuum: a virtual rhizotron study

2018 ◽  
Author(s):  
Sathyanarayan Rao ◽  
Félicien Meunier ◽  
Solomon Ehosioke ◽  
Nolwenn Lesparre ◽  
Andreas Kemna ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electrical Properties ◽  
Root Growth ◽  
Water Content ◽  
Soil Water ◽  
Water Uptake ◽  
Numerical Study ◽  
Root Segments ◽  
Bulk Electrical Conductivity ◽  
The Impact

Abstract. Electrical Resistivity Tomography (ERT) has become an important tool to study soil water fluxes in cropped field. ERT results translates to water content via empirical pedophysical relations that take soil physical properties into account, usually ignoring the impact of roots. Studies shows high root dense soils behaves quite differently than less root dense soils in terms of bulk electrical conductivity. Yet, we do not completely understand the impact of root segments on the ERT measurements. In this numerical study, we coupled an electrical model with a plant-soil water flow model to investigate the impact of plant root growth and water uptake on the ERT virtual experiment. The electrical properties of roots were explicitly accounted in the finite element mesh and we obtained the electrical conductivities of root segments by conducting specific experiments on real maize plants. The contrast between electrical conductivity of roots and soil depends on factors such as root density, irrigation, root age, and root water uptake pattern. Root growth and water uptake processes thus affect this contrast together with the soil electrical properties. Model results indicate a non-negligible anisotropy in bulk electrical conductivity induced by root processes. We see a greater anisotropy in a sandy medium when compared to a loamy medium. We find that the water uptake process dominates the bulk electrical properties. The Gauss-Newton type ERT inversion of virtual rhizotron data demonstrate that, when root-soil electrical conductivity contrasts are high, it can lead to error in water content estimates since the electrical conductivity is partly due to root. Thus, incorporating the impact of root in the pedophysical relations is very important to interpret ERT results directly as water content.

Computational Modeling of Cardiac Ablation Incorporating Electrothermomechanical Interactions

2020 ◽  
Vol 3 (4) ◽  
Author(s):  
Sundeep Singh ◽  
Roderick Melnik
Keyword(s):  
Blood Flow ◽  
Computational Modeling ◽  
Radio Frequency ◽  
Treatment Outcomes ◽  
Cardiac Tissue ◽  
Numerical Study ◽  
Cardiac Ablation ◽  
Cardiac Chamber ◽  
Ablation Volume ◽  
Fully Coupled

Abstract The application of radio frequency ablation (RFA) has been widely explored in treating various types of cardiac arrhythmias. Computational modeling provides a safe and viable alternative to ex vivo and in vivo experimental studies for quantifying the effects of different variables efficiently and reliably, apart from providing a priori estimates of the ablation volume attained during cardiac ablation procedures. In this contribution, we report a fully coupled electrothermomechanical model for a more accurate prediction of the treatment outcomes during the radio frequency cardiac ablation. A numerical model comprising of cardiac tissue and the cardiac chamber has been developed in which an electrode has been inserted perpendicular to the cardiac tissue to simulate actual clinical procedures. Temperature-dependent heat capacity, electrical and thermal conductivities, and blood perfusion rate have been considered to model more realistic scenarios. The effects of blood flow and contact force of the electrode tip on the treatment outcomes of a fully coupled model of RFA have been systematically investigated. The numerical study demonstrates that the predicted ablation volume of RFA is significantly dependent on the blood flow rate in the cardiac chamber and also on the tissue deformation induced due to electrode insertion depth of 1.5 mm or higher.

Effect of FCI Electrical Conductivity on MHD Flow in Channels With Multi-Layer Inserts for Fusion Blanket

2013 ◽  
Author(s):  
Heng Zhang ◽  
Tao Zhou ◽  
Zi Meng ◽  
Hongli Chen
Keyword(s):  
Electrical Conductivity ◽  
Liquid Metal ◽  
Numerical Study ◽  
Electromagnetic Coupling ◽  
Mhd Flow ◽  
Flow Channel ◽  
Efficient Production ◽  
Outlet Temperature ◽  
High Efficient ◽  
Production Of Hydrogen

Fusion blanket is a key component for energy transformation and extraction in fusion reactor, in many kinds of blanket designs, the flow channel insert (FCI) made of a silicon carbide composite (SiCf/SiC) is a key element, which serves as electric and thermal insulator. In the high temperature liquid metal blanket (HTL) of fusion-based hydrogen production reactor (named FDS-III),. The multilayer flow channel inserts (MFCI) are put into the breeding zone to achieve the LiPb outlet temperature around 1000°C for high efficient production of hydrogen. However, the flow of liquid metal meandering through MFCI will cause strong magnetohydrodynamic (MHD) effect under the influence of the intense fusion magnetic field and the liquid metal in the neighboring channels will effect each other. When the FCI conductivity varies, the influence varies coresspondingly. So MHD effect of different FCI electrical conductivity is a key issue which should be concerned in HTL blanket. In this work, the numerical study aims at clarifying the MHD effect for liquid metal LiPb in the multi-layer flow channel inserts of different conductivity by using a code named MTC-H 2.0. The MHD flows with Special geometry of the HTL flow channels with MFCI were considered, velocity and FCI electrical conductivity’s effect on electromagnetic coupling are discussed.

scholarly journals Relation between denaturation time measured by optical coherence reflectometry and thermal lesion depth during radiofrequency cardiac ablation: Feasibility numerical study

2017 ◽  
Vol 50 (3) ◽  
pp. 222-229 ◽  
Author(s):  
Ana González-Suárez ◽  
David Herranz ◽  
Enrique Berjano ◽  
Jose L. Rubio-Guivernau ◽  
Eduardo Margallo-Balbás
Keyword(s):  
Numerical Study ◽  
Optical Coherence ◽  
Cardiac Ablation ◽  
Thermal Lesion ◽  
Lesion Depth

Computational Model of Radiofrequency Ablation of Cardiac Tissues Incorporating Thermo-Electro-Mechanical Interactions

2020 ◽  
Author(s):  
Sundeep Singh ◽  
Roderick Melnik
Keyword(s):  
Radiofrequency Ablation ◽  
Cardiac Tissue ◽  
A Priori Estimates ◽  
Ex Vivo ◽  
Numerical Study ◽  
Experimental Studies ◽  
Computational Modelling ◽  
Cardiac Ablation ◽  
Fully Coupled

Abstract The application of radiofrequency ablation (RFA) has been widely explored in treating various types of cardiac arrhythmias. Computational modelling provides a safe and viable alternative to ex vivo and in vivo experimental studies for quantifying the effects of different variables efficiently and reliably, apart from providing a priori estimates of the ablation volume attained during cardiac ablation procedures. In this contribution, we report a fully coupled thermo-electro-mechanical model for a more accurate prediction of the treatment outcomes during the radiofrequency cardiac ablation. A numerical model comprising of cardiac tissue and the cardiac chamber has been developed in which an electrode has been inserted perpendicular to the cardiac tissue to simulate actual clinical procedures. Temperature-dependent heat capacity, electrical and thermal conductivities, and blood perfusion rate have been considered to model more realistic scenarios. The effects of blood flow and contact force of the electrode tip on the efficacy of a fully coupled model of RFA have been systematically investigated. The numerical study predicts that the efficacy of RFA is significantly dependent on the thermo-electro-mechanical parameters of the cardiac tissue.

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