Graphene-based microwave coaxial antenna for microwave ablation: thermal analysis

2020 ◽  
pp. 1-9
Author(s):  
Burak Uzman ◽  
Adem Yilmaz ◽  
Hulusi Acikgoz ◽  
Raj Mittra
Keyword(s):  
Relaxation Time ◽  
Microwave Ablation ◽  
Graphene Layer ◽  
Heat Dissipation ◽  
Chemical Potential ◽  
Treatment Time ◽  
Slot Antenna ◽  
Necrotic Tissue ◽  
Cancerous Tissue ◽  
High Impedance

Abstract In this study, the problem of backward heating in microwave ablation technique is examined and an electromagnetic solution based on the use of high impedance graphene material is presented for its mitigation. In this context, a one-atom-thick graphene layer is added on the coaxial double slot antenna. In addition to the electromagnetic behavior, thermal effects caused by the graphene-covered antenna are emphasized. The graphene's conductivity being highly dependent on its chemical potential and the relaxation time, a parametric study is performed to determine a range of tolerances within which the graphene-coated antenna outperform a typical graphene-free antenna. The range of values is found to be 0 < μ c < 0.5 eV and τ < 0.4 ps, for the chemical potential and the relaxation time, respectively. The backward heating problem being prevented, the ablation region is ensured to be spherical around the tip of the antenna. Effects of the graphene layer to the heat dissipation in the tissue, the necrotic tissue ratio (damage to the cancerous tissue of the caused by electromagnetic energy), and the treatment time using the coaxial double slot antenna were examined. The results show that the heat dissipation is concentrated around the slots (region of cancerous tissue) and a higher necrotic tissue ratio can be achieved with a graphene-covered double slot antenna in a shorter time.

scholarly journals Coupling of waveguide mode and graphene plasmons

2021 ◽  
Vol 255 ◽  
pp. 07002
Author(s):  
Jiří Petráček ◽  
Jiří Čtyroký ◽  
Vladimír Kuzmiak ◽  
Pavel Kwiecien ◽  
Ivan Richter
Keyword(s):  
Low Power ◽  
Graphene Layer ◽  
Waveguide Mode ◽  
Chemical Potential ◽  
Temperature Sensing ◽  
Graphene Layers ◽  
Optical Wavelength ◽  
Electro Optic ◽  
Photonic Waveguides ◽  
Graphene Plasmons

Photonic waveguides with graphene layers have been recently studied for their potential as fast and low-power electro-optic modulators with small footprints. We show that in the optical wavelength range of 1.55 μm, surface plasmons supported by the graphene layer with the chemical potential exceeding ~0.5 eV can couple with the waveguide mode and affect its propagation. This effect might be possibly utilized in technical applications as a very low-power amplitude modulation, temperature sensing, etc.

scholarly journals Research on Perfect and Tunable Metamaterial Absorber Based on Crosshair-shaped Graphene

2021 ◽  
Vol 2109 (1) ◽  
pp. 012015
Author(s):  
Yiran Guo ◽  
Yunping Qi ◽  
Chuqin Liu ◽  
Weiming Liu ◽  
Xiangxian Wang
Keyword(s):  
Relaxation Time ◽  
Chemical Potential ◽  
Incident Angle ◽  
Fdtd Method ◽  
Reference Value ◽  
Metamaterial Absorber ◽  
Selective Absorption ◽  
Perfect Absorber ◽  
Wide Angle ◽  
Perfect Absorption

Abstract Graphene, as a new nano-material, according to the physical properties of electric field localization and selective absorption on light of surface plasmon resonance (SPR), a tunable, multi-band and wide-angle perfect absorber based on crosshair-shaped graphene is devised by using the Finite Difference in Time Domain (FDTD) method. In this paper, the effects of chemical potential, relaxation time, and incident angle of light on the absorptivity of graphene are systematically discussed. The simulation experiment shows that there are two absorption peaks with perfect absorption rate appeared in the study range, and the maximum modulation index can be obtained by changing the relaxation time. Finally, it proves that the absorber is insensitive to wide-angle of light. Thus, it is able to be concluded that the absorber has a great reference value to sensor, wireless communication, biomedical and other fields.

scholarly journals Engineered heat dissipation and current distribution boron nitride-graphene layer coated on polypropylene separator for high performance lithium metal battery

2021 ◽  
Vol 583 ◽  
pp. 362-370
Author(s):  
Jassiel R. Rodriguez ◽  
Patrick J. Kim ◽  
Kyungho Kim ◽  
Zhimin Qi ◽  
Haiyan Wang ◽  
...  
Keyword(s):  
Boron Nitride ◽  
Current Distribution ◽  
High Performance ◽  
Graphene Layer ◽  
Heat Dissipation ◽  
Lithium Metal ◽  
Lithium Metal Battery ◽  
Polypropylene Separator

scholarly journals Feasibility of Using a Novel 2.45 GHz Double Short Distance Slot Coaxial Antenna for Minimally Invasive Cancer Breast Microwave Ablation Therapy: Computational Model, Phantom, and In Vivo Swine Experimentation

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
R. Ortega-Palacios ◽  
C. J. Trujillo-Romero ◽  
M. F. J. Cepeda Rubio ◽  
A. Vera ◽  
L. Leija ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Minimally Invasive ◽  
Computational Model ◽  
Short Distance ◽  
Microwave Ablation ◽  
Slot Antenna ◽  
Invasive Treatment ◽  
Promising Alternative ◽  
Ablation Therapy

Microwave ablation (MWA) by using coaxial antennas is a promising alternative for breast cancer treatment. A double short distance slot coaxial antenna as a newly optimized applicator for minimally invasive treatment of breast cancer is proposed. To validate and to analyze the feasibility of using this method in clinical treatment, a computational model, phantom, and breast swine in vivo experimentation were carried out, by using four microwave powers (50 W, 30 W, 20 W, and 10 W). The finite element method (FEM) was used to develop the computational model. Phantom experimentation was carried out in breast phantom. The in vivo experimentation was carried out in a 90 kg swine sow. Tissue damage was estimated by comparing control and treated micrographs of the porcine mammary gland samples. The coaxial slot antenna was inserted in swine breast glands by using image-guided ultrasound. In all cases, modeling, in vivo and phantom experimentation, and ablation temperatures (above 60°C) were reached. The in vivo experiments suggest that this new MWA applicator could be successfully used to eliminate precise and small areas of tissue (around 20–30 mm2). By modulating the power and time applied, it may be possible to increase/decrease the ablation area.

Microwave ablation to treat bone tumors by using a double slot antenna: A modelling study

2017 ◽  
Author(s):  
C.J. Trujillo-Romero ◽  
G. Rico-Martinez ◽  
L. Leija-Salas ◽  
A. Vera-Hernandez ◽  
J. Gutierrez-Martinez
Keyword(s):  
Microwave Ablation ◽  
Bone Tumors ◽  
Slot Antenna ◽  
Modelling Study

scholarly journals DIRECTIONAL DUAL-BAND SLOT ANTENNA WITH DUAL-BANDGAP HIGH-IMPEDANCE-SURFACE REFLECTOR

2009 ◽  
Vol 9 ◽  
pp. 1-11 ◽  
Author(s):  
Xiu Long Bao ◽  
Giuseppe Ruvio ◽  
Max J. Ammann
Keyword(s):  
Dual Band ◽  
Slot Antenna ◽  
Impédance Surface ◽  
Impedance Surface ◽  
High Impedance ◽  
High Impedance Surface

Interaction of hyperthermia and heart rate on stroke volume during prolonged exercise

2010 ◽  
Vol 109 (3) ◽  
pp. 745-751 ◽  
Author(s):  
Joel D. Trinity ◽  
Matthew D. Pahnke ◽  
Joshua F. Lee ◽  
Edward F. Coyle
Keyword(s):  
Heart Rate ◽  
Stroke Volume ◽  
Heat Dissipation ◽  
Low Dose ◽  
Prolonged Exercise ◽  
Treatment Time ◽  
Placebo Control ◽  
Experimental Conditions ◽  
Time Interaction ◽  
Ventricular Filling

People who become hyperthermic during exercise display large increases in heart rate (HR) and reductions in stroke volume (SV). It is not clear if the reduction in SV is due primarily to hyperthermia or if it is a secondary effect of an elevation in HR reducing ventricular filling. In the present study, the upward drift of HR during prolonged exercise was prevented by a very small dose of the β1-adrenoreceptor blocker (atenolol; βB), thus allowing SV to be compared at a given HR during normothermia and hyperthermia. Eleven men cycled for 60 min at 57% of peak O2 uptake after receiving placebo control (PL) or a low dose (0.2 mg/kg) of βB. Hyperthermia was induced by reducing heat dissipation during exercise. Four experimental conditions were studied: normothermia-PL, normothermia-βB, hyperthermia-PL, and hyperthermia-βB. Hyperthermia increased skin and core temperature by 4.3°C and 0.8°C ( P < 0.01), respectively. βB prevented HR elevation with hyperthermia: HR values were similar at minute 60 during normothermia-PL and hyperthermia-βB (155 ± 11 and 154 ± 13 beats/min, respectively, P = 0.82). However, SV was increased by 7% during the final 20 min of exercise during hyperthermia-βB compared with normothermia-PL (treatment × time interaction, P = 0.03). In conclusion, when matched for HR, mild hyperthermia increased SV during exercise. Furthermore, the reduction in SV throughout prolonged exercise under normothermic and mildly hyperthermic conditions appears to be due to the increase in HR.

scholarly journals THERMAL EVOLUTION OF A RADIATING ANISOTROPIC STAR WITH SHEAR

2006 ◽  
Vol 15 (07) ◽  
pp. 1053-1065 ◽  
Author(s):  
N. F. NAIDU ◽  
M. GOVENDER ◽  
K. S. GOVINDER
Keyword(s):  
Heat Flux ◽  
Relaxation Time ◽  
Heat Dissipation ◽  
Thermal Evolution ◽  
Spherically Symmetric ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Pressure Anisotropy ◽  
Radiating Star ◽  
Anisotropic Star

We study the effects of pressure anisotropy and heat dissipation in a spherically symmetric radiating star undergoing gravitational collapse. An exact solution of the Einstein field equations is presented in which the model has a Friedmann-like limit when the heat flux vanishes. The behavior of the temperature profile of the evolving star is investigated within the framework of causal thermodynamics. In particular, we show that there are significant differences between the relaxation time for the heat flux and the relaxation time for the shear stress.

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