An Experimental and Numerical Investigation of Phase Change Electrodes for Therapeutic Irreversible Electroporation

2013 ◽  
Vol 135 (11) ◽  
Author(s):  
Christopher B. Arena ◽  
Roop L. Mahajan ◽  
Marissa Nichole Rylander ◽  
Rafael V. Davalos
Keyword(s):  
Phase Change ◽  
Electric Fields ◽  
Heat Dissipation ◽  
Transfer Problem ◽  
New Technology ◽  
Irreversible Electroporation ◽  
Surrounding Tissue ◽  
High Dose ◽  
Target Tissue ◽  
Ablation Volume

Irreversible electroporation (IRE) is a new technology for ablating aberrant tissue that utilizes pulsed electric fields (PEFs) to kill cells by destabilizing their plasma membrane. When treatments are planned correctly, the pulse parameters and location of the electrodes for delivering the pulses are selected to permit destruction of the target tissue without causing thermal damage to the surrounding structures. This allows for the treatment of surgically inoperable masses that are located near major blood vessels and nerves. In select cases of high-dose IRE, where a large ablation volume is desired without increasing the number of electrode insertions, it can become challenging to design a pulse protocol that is inherently nonthermal. To solve this problem we have developed a new electrosurgical device that requires no external equipment or protocol modifications. The design incorporates a phase change material (PCM) into the electrode core that melts during treatment and absorbs heat out of the surrounding tissue. Here, this idea is reduced to practice by testing hollow electrodes filled with gallium on tissue phantoms and monitoring temperature in real time. Additionally, the experimental data generated are used to validate a numerical model of the heat transfer problem, which is then applied to investigate the cooling performance of other classes of PCMs. The results indicate that metallic PCMs, such as gallium, are better suited than organics or salt hydrates for thermal management, because their comparatively higher thermal conductivity aids in heat dissipation. However, the melting point of the metallic PCM must be properly adjusted to ensure that the phase transition is not completed before the end of treatment. When translated clinically, phase change electrodes have the potential to continue to allow IRE to be performed safely near critical structures, even in high-dose cases.

Phase Change Electrodes for Reducing Joule Heating During Irreversible Electroporation

2012 ◽  
Author(s):  
Christopher B. Arena ◽  
Roop L. Mahajan ◽  
Marissa Nichole Rylander ◽  
Rafael V. Davalos
Keyword(s):  
Cell Death ◽  
Electric Fields ◽  
Electric Field Distribution ◽  
Irreversible Electroporation ◽  
Tissue Ablation ◽  
Thermal Processes ◽  
Ablation Volume ◽  
Extracellular Matrix Components ◽  
Membrane Defects ◽  
Viable Treatment

Irreversible electroporation (IRE) is a non-thermal tissue ablation modality that is gaining momentum as a viable treatment option for tumors and other non-cancerous pathologies [1]. The protocol consists of delivering a series of short (∼ 100 μs) and intense (∼ 1000 V/cm) pulsed electric fields through electrodes inserted directly into or around a targeted tissue. The pulses induce a rapid buildup of charge across the plasma membrane of cells comprising the tissue that results in the creation of permanent membrane defects, ultimately leading to cell death. Because the extent of cell death relies predominately on the extent of charge buildup and not thermal processes, extracellular matrix components are spared, including major nerve and blood vessel architecture. Additionally, the ablation volume is predictable based on the electric field distribution and visible in real-time via MRI, CT, and ultrasound.

scholarly journals Concept for parallel placement of flexible needles for Irreversible Electroporation

2021 ◽  
Vol 7 (2) ◽  
pp. 219-222
Author(s):  
Hanbal Arif ◽  
Uwe Bernd Liehr ◽  
Johann Jakob Wendler ◽  
Michael Friebe ◽  
Axel Boese
Keyword(s):  
Prostate Cancer ◽  
Cancer Cells ◽  
Electric Fields ◽  
High Speed ◽  
Irreversible Electroporation ◽  
The Body ◽  
Target Tissue ◽  
Needle Placement ◽  
Prostate Cancer Treatment ◽  
Electrical Pulses

Abstract Irreversible Electroporation (IRE) is a non-thermal tumor ablation treatment applicable for prostate cancer. IRE uses ultra-short but strong electrical pulses to destroy cancer cells nonthermally [1]. Clinically available IRE therapy requires two or more needle electrodes placed around the target tissue to apply the electric fields. A pre-requirement to achieve successful and effective ablation is an accurate and parallel needle placement to cover the tumor zone. Differences in tissue density, organ surface curvature as well as organ and patient motion in combination with long and highly flexible needle electrodes causes’ difficulties to achieve the desired target accuracy during needle placement process. We propose a concept of a shooting mechanism in combination with a grid template support to improve the parallel needle placement process for prostate cancer treatment. Instead of conventionally inserting the needle in the body by hand, it can be placed with high speed using a shooting device setup, that works similar like a biopsy gun.

scholarly journals Numerical Study of a Cooling System Using Phase Change of a Refrigerant in a Thermosyphon

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3634
Author(s):  
Grzegorz Czerwiński ◽  
Jerzy Wołoszyn
Keyword(s):  
Mass Transfer ◽  
Phase Change ◽  
Heat Dissipation ◽  
Cooling System ◽  
Numerical Study ◽  
Relaxation Parameter ◽  
Phase Changes ◽  
Transfer Time ◽  
Two Phase ◽  
Time Relaxation

With the increasing trend toward the miniaturization of electronic devices, the issue of heat dissipation becomes essential. The use of phase changes in a two-phase closed thermosyphon (TPCT) enables a significant reduction in the heat generated even at high temperatures. In this paper, we propose a modification of the evaporation–condensation model implemented in ANSYS Fluent. The modification was to manipulate the value of the mass transfer time relaxation parameter for evaporation and condensation. The developed model in the form of a UDF script allowed the introduction of additional source equations, and the obtained solution is compared with the results available in the literature. The variable value of the mass transfer time relaxation parameter during condensation rc depending on the density of the liquid and vapour phase was taken into account in the calculations. However, compared to previous numerical studies, more accurate modelling of the phase change phenomenon of the medium in the thermosyphon was possible by adopting a mass transfer time relaxation parameter during evaporation re = 1. The assumption of ten-fold higher values resulted in overestimated temperature values in all sections of the thermosyphon. Hence, the coefficient re should be selected individually depending on the case under study. A too large value may cause difficulties in obtaining the convergence of solutions, which, in the case of numerical grids with many elements (especially three-dimensional), significantly increases the computation time.

scholarly journals High-Dose Vincristine Sulfate Liposome Injection for Advanced, Relapsed, and Refractory Adult Philadelphia Chromosome–Negative Acute Lymphoblastic Leukemia

2013 ◽  
Vol 31 (6) ◽  
pp. 676-683 ◽  
Author(s):  
Susan O'Brien ◽  
Gary Schiller ◽  
John Lister ◽  
Lloyd Damon ◽  
Stuart Goldberg ◽  
...  
Keyword(s):  
Acute Lymphoblastic Leukemia ◽  
Hematopoietic Cell Transplantation ◽  
Lymphoblastic Leukemia ◽  
Philadelphia Chromosome ◽  
Chemotherapy Resistance ◽  
High Dose ◽  
Rapid Progression ◽  
Target Tissue ◽  
Vincristine Sulfate ◽  
Pivotal Phase

Purpose Relapsed adult acute lymphoblastic leukemia (ALL) is associated with high reinduction mortality, chemotherapy resistance, and rapid progression leading to death. Vincristine sulfate liposome injection (VSLI), sphingomyelin and cholesterol nanoparticle vincristine (VCR), facilitates VCR dose-intensification and densification plus enhances target tissue delivery. We evaluated high-dose VSLI monotherapy in adults with Philadelphia chromosome (Ph) –negative ALL that was multiply relapsed, relapsed and refractory to reinduction, and/or relapsed after hematopoietic cell transplantation (HCT). Patients and Methods Sixty-five adults with Ph-negative ALL in second or greater relapse or whose disease had progressed following two or more leukemia therapies were treated in this pivotal phase II, multinational trial. Intravenous VSLI 2.25 mg/m2, without dose capping, was administered once per week until response, progression, toxicity, or pursuit of HCT. The primary end point was achievement of complete response (CR) or CR with incomplete hematologic recovery (CRi). Results The CR/CRi rate was 20% and overall response rate was 35%. VSLI monotherapy was effective as third-, fourth-, and fifth-line therapy and in patients refractory to other single- and multiagent reinduction therapies. Median CR/CRi duration was 23 weeks (range, 5 to 66 weeks); 12 patients bridged to a post-VSLI HCT, and five patients were long-term survivors. VSLI was generally well tolerated and associated with a low 30-day mortality rate (12%). Conclusion High-dose VSLI monotherapy resulted in meaningful clinical outcomes including durable responses and bridging to HCT in advanced ALL settings. The toxicity profile of VSLI was predictable, manageable, and comparable to standard VCR despite the delivery of large, normally unachievable, individual and cumulative doses of VCR.

Ceramic-Based Planar Heat Pipe (Plate) for Passive Electronics Cooling

2011 ◽  
Vol 2011 (CICMT) ◽  
pp. 000159-000165
Author(s):  
M. Wilson ◽  
H. Anderson ◽  
J. Fellows ◽  
C. Lewinsohn
Keyword(s):  
Integrated Circuits ◽  
Phase Change ◽  
Heat Dissipation ◽  
Thermal Contact ◽  
Three Dimensional ◽  
Electronics Cooling ◽  
Ceramic Materials ◽  
Back Side ◽  
Dimensional Network ◽  
Internal Networks

Heat dissipation has become a major hurdle for the electronics industry, especially as higher performance integrated circuits are being developed for the power industry. Two of the primary hurdles in dissipating this heat are:The thermal contact resistance between the IC and the cooling device.The ability to effectively spread the heat, such that traditional cooling technologies can be effective.By selecting ceramic materials that are thermo-mechanically matched (CTE) to IC materials, the proposed heat plate can be directly bonded by typical solder or braze techniques to the back-side of the IC. This eliminates thermal resistances due to contact and thermal interface materials. Within these heat plates, a three dimensional network of gas channels and fluid wicks spread the high-flux heat loads from localized hot spots to the surrounding regions via phase change fluids and mass transport. Like traditional heat pipes, these heat plates operate at nearly uniform temperature due to the phase change. The internal networks provide for multidimensional heat and mass flow, increasing their dissipating capability. By using matched ceramic materials, and the inclusion of a heat plate, these primary hurdles for heat dissipation can be mitigated. The performance of prototypical planar heat plates will be presented.

scholarly journals A Study on Nonthermal Irreversible Electroporation of the Thyroid

2019 ◽  
Vol 18 ◽  
pp. 153303381987630
Author(s):  
Yanpeng Lv ◽  
Yanfang Zhang ◽  
Jianwei Huang ◽  
Yunlong Wang ◽  
Boris Rubinsky
Keyword(s):  
Electric Fields ◽  
Thermal Damage ◽  
Irreversible Electroporation ◽  
Pulse Sequences ◽  
Cell Swelling ◽  
Tissue Type ◽  
Heterogeneous Structure ◽  
Treatment Protocols ◽  
Thyroid Ablation ◽  
Nonthermal Irreversible Electroporation

Background: Nonthermal irreversible electroporation is a minimally invasive surgery technology that employs high and brief electric fields to ablate undesirable tissues. Nonthermal irreversible electroporation can ablate only cells while preserving intact functional properties of the extracellular structures. Therefore, nonthermal irreversible electroporation can be used to ablate tissues safely near large blood vessels, the esophagus, or nerves. This suggests that it could be used for thyroid ablation abutting the esophagus. This study examines the feasibility of using nonthermal irreversible electroporation for thyroid ablation. Methods: Rats were used to evaluate the effects of nonthermal irreversible electroporation on the thyroid. The procedure entails the delivery of high electric field pulses (1-3 kV/cm, 100 microseconds) between 2 surface electrodes bracing the thyroid. The right lobe was treated with various nonthermal irreversible electroporation pulse sequences, and the left was the control. After 24 hours of the nonthermal irreversible electroporation treatment, the thyroid was examined with hemotoxylin and eosin histological analysis. Mathematical models of electric fields and the Joule heating-induced temperature raise in the thyroid were developed to examine the experimental results. Results: Treatment with nonthermal irreversible electroporation leads to follicular cells damage, associated with cell swelling, inflammatory cell infiltration, and cell ablation. Nonthermal irreversible electroporation spares the trachea structure. Unusually high electric fields, for these types of tissue, 3000 V/cm, are needed for thyroid ablation. The mathematical model suggests that this may be related to the heterogeneous structure of the thyroid-induced distortion of local electric fields. Moreover, most of the tissue does not experience thermal damage inducing temperature elevation. However, the heterogeneous structure of the thyroid may cause local hot spots with the potential for local thermal damage. Conclusion: Nonthermal irreversible electroporation with 3000 V/cm can be used for thyroid ablation. Possible applications are treatment of hyperthyroidism and thyroid cancer. The highly heterogeneous structure of the thyroid distorts the electric fields and temperature distribution in the thyroid must be considered when designing treatment protocols for this tissue type.

Effect of a High Electric Field on the Thermal and Phase Change Characteristics of an Impacting Drop

2019 ◽  
Author(s):  
Abhishek Basavanna ◽  
Prajakta Khapekar ◽  
Navdeep Singh Dhillon
Keyword(s):  
Heat Transfer ◽  
Electric Field ◽  
Phase Change ◽  
Electric Fields ◽  
High Speed ◽  
Impact Behavior ◽  
Liquid Drops ◽  
Active Interest ◽  
Post Impact ◽  
High Electric Fields

Abstract The effect of applied electric fields on the behavior of liquids and their interaction with solid surfaces has been a topic of active interest for many decades. This has important implications in phase change heat transfer processes such as evaporation, boiling, and condensation. Although the effect of low to moderate voltages has been studied, there is a need to explore the interaction of high electric fields with liquid drops and bubbles, and their effect on heat transfer and phase change. In this study, we employ a high speed optical camera to study the dynamics of a liquid drop impacting a hot substrate under the application of high electric fields. Experimental results indicate a significant change in the pre- and post-impact behavior of the drop. Prior to impact, the applied electric field elongates the drop in the direction of the electric field. Post-impact, the recoil phase of the drop is significantly affected by charging effects. Further, a significant amount of micro-droplet ejection is observed with an increase in the applied voltage.

scholarly journals Precise nanoscale temperature mapping in operational microelectronic devices by use of a phase change material

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Qilong Cheng ◽  
Sukumar Rajauria ◽  
Erhard Schreck ◽  
Robert Smith ◽  
Na Wang ◽  
...  
Keyword(s):  
Thin Film ◽  
Phase Change ◽  
Phase Change Material ◽  
Heat Dissipation ◽  
Radiation Thermometry ◽  
High Vacuum ◽  
Operating Conditions ◽  
Ultra High Vacuum ◽  
Scanning Thermal Microscopy ◽  
Change Material

AbstractThe microelectronics industry is pushing the fundamental limit on the physical size of individual elements to produce faster and more powerful integrated chips. These chips have nanoscale features that dissipate power resulting in nanoscale hotspots leading to device failures. To understand the reliability impact of the hotspots, the device needs to be tested under the actual operating conditions. Therefore, the development of high-resolution thermometry techniques is required to understand the heat dissipation processes during the device operation. Recently, several thermometry techniques have been proposed, such as radiation thermometry, thermocouple based contact thermometry, scanning thermal microscopy, scanning transmission electron microscopy and transition based threshold thermometers. However, most of these techniques have limitations including the need for extensive calibration, perturbation of the actual device temperature, low throughput, and the use of ultra-high vacuum. Here, we present a facile technique, which uses a thin film contact thermometer based on the phase change material $$Ge_2 Sb_2 Te_5$$ G e 2 S b 2 T e 5 , to precisely map thermal contours from the nanoscale to the microscale. $$Ge_2 Sb_2 Te_5$$ G e 2 S b 2 T e 5 undergoes a crystalline transition at $$\hbox {T}_{{g}}$$ T g with large changes in its electric conductivity, optical reflectivity and density. Using this approach, we map the surface temperature of a nanowire and an embedded micro-heater on the same chip where the scales of the temperature contours differ by three orders of magnitude. The spatial resolution can be as high as 20 nanometers thanks to the continuous nature of the thin film.

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