Temperature Elevation in the Human Eye Due To Intraocular Projection Prosthesis Device

2021 ◽  
Vol 13 (6) ◽  
Author(s):  
Dipika Gongal ◽  
Siddhant Thakur ◽  
Ashay Panse ◽  
John A. Stark ◽  
Charles Q. Yu ◽  
...  
Keyword(s):  
Power Dissipation ◽  
Corneal Transplantation ◽  
Blood Perfusion ◽  
Element Model ◽  
Corneal Opacity ◽  
Implantable Devices ◽  
Tissue Temperature ◽  
Eye Model ◽  
Bionic Eye ◽  
Transient Thermal

Abstract Corneal opacity is a leading cause of blindness worldwide. Corneal transplantation and keratoprosthesis can restore vision but have limitations due to the shortage of donor corneas and complications due to infection. A proposed alternative treatment using an intraocular projection prosthesis device can treat corneal disease. In this study, we perform a transient thermal analysis of the bionic eye model to determine the power the device can produce without elevating the eye tissue temperature above the 2°C limit imposed by the international standard for implantable devices. A 3D finite element model, including blood perfusion and natural convection fluid flow of the eye, was created. The device was placed 1.95 mm from the iris, which experienced less than 2°C rise in the tissue temperature at a maximum power dissipation of LED at 100 mW and microdisplay at 25 mW.

scholarly journals Analysis of the effect of external heating in the human tissue: A finite element approach

2020 ◽  
Vol 26 (4) ◽  
pp. 251-262
Author(s):  
Mridul Sannyal ◽  
Abul Mukid Mohammad Mukaddes ◽  
Md. Matiar Rahman ◽  
M. A. H. Mithu
Keyword(s):  
Finite Element ◽  
Human Tissue ◽  
Transfer Problem ◽  
Thermal Response ◽  
Blood Perfusion ◽  
Element Model ◽  
Bioheat Transfer ◽  
Tissue Temperature ◽  
Blood Temperature ◽  
External Heating

AbstractThermal therapy which involves either raising or lowering tissue temperature to treat malignant cells needs precise acknowledgment of thermal history inside the biological system to ensure effective treatment. For this purpose, this study presents a two-dimensional unsteady finite element model (FEM) of the bioheat transfer problem based on Pennes bio-heat equation to analyze the thermal response of tissue subject to external heating. Crank-Nikolson scheme was used for the unsteady solution. A finite element code was developed using C language to calculate results. The obtained numerical result was compared with the analytical and other numerical results available in the literature. A good agreement was found from the comparison. Temperature distribution inside the human body due to constant and sinusoidal spatial and surface heating were analyzed. Response to point heating was also investigated. Moreover, a sensitivity analysis was carried out to know the effect of various parameters, i.e. blood temperature, thermal conductivity, and blood perfusion rate on tissue temperature. The outcome of this study will be helpful for the researchers and physicians involved in the thermal treatment of human tissue.

Lumped Parameter Thermal Model for the Study of Vascular Reactivity in the Fingertip

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
O. Ley ◽  
C. Deshpande ◽  
B. Prapamcham ◽  
M. Naghavi
Keyword(s):  
Heat Flux ◽  
Blood Flow ◽  
Thermal Model ◽  
Vascular Reactivity ◽  
Arterial Occlusion ◽  
Blood Perfusion ◽  
Cost Effective ◽  
Venous Occlusion ◽  
Cardiovascular Complications ◽  
Tissue Temperature

Vascular reactivity (VR) denotes changes in volumetric blood flow in response to arterial occlusion. Current techniques to study VR rely on monitoring blood flow parameters and serve to predict the risk of future cardiovascular complications. Because tissue temperature is directly impacted by blood flow, a simplified thermal model was developed to study the alterations in fingertip temperature during arterial occlusion and subsequent reperfusion (hyperemia). This work shows that fingertip temperature variation during VR test can be used as a cost-effective alternative to blood perfusion monitoring. The model developed introduces a function to approximate the temporal alterations in blood volume during VR tests. Parametric studies are performed to analyze the effects of blood perfusion alterations, as well as any environmental contribution to fingertip temperature. Experiments were performed on eight healthy volunteers to study the thermal effect of 3min of arterial occlusion and subsequent reperfusion (hyperemia). Fingertip temperature and heat flux were measured at the occluded and control fingers, and the finger blood perfusion was determined using venous occlusion plethysmography (VOP). The model was able to phenomenologically reproduce the experimental measurements. Significant variability was observed in the starting fingertip temperature and heat flux measurements among subjects. Difficulty in achieving thermal equilibration was observed, which indicates the important effect of initial temperature and thermal trend (i.e., vasoconstriction, vasodilatation, and oscillations).

Bionic-EyE: Eye Model for Simulating Glaucoma Oparation

2018 ◽  
Vol 2018 (0) ◽  
pp. 1P1-L03
Author(s):  
Seiji Omata ◽  
Kazuki Ohashi ◽  
Mahmoud Gallab ◽  
Kanako Harada ◽  
Mamoru Mitsuishij ◽  
...  
Keyword(s):  
Eye Model ◽  
Bionic Eye

Temperature Profiles in a Finite Element Thermal Model of the Prostate Region Under Hyperthermia Treatment

1990 ◽  
Vol 189 ◽  
Author(s):  
Indira Chatterjee ◽  
Roy E. Adams ◽  
Namdar Saniei
Keyword(s):  
Finite Element ◽  
Phased Array ◽  
Blood Perfusion ◽  
Element Model ◽  
Bioheat Transfer ◽  
Transient Temperature ◽  
Temperature Profiles ◽  
Hyperthermia Treatment ◽  
Finite Element Software ◽  
Transient Temperature Distribution

ABSTRACTThe detailed transient temperature distribution in an inhomogeneous model of a cross section through the prostate region of the human body undergoing hyperthermia treatment forcancer has been calculated. The finite element method has been used to solve the bioheattransfer equation. A commercially available finite element software package called ANSYS® has been adapted to the present problem.The model consists of 523 triangular elements and incorporates a tumor in the prostate.The hyperthermia device under test is an Annular Phased Array consisting of dipole antennas. The model is surrounded by a bolus of deionized water. The calculated electromagnetic energy distribution is input into the bioheat transfer equation and the resulting temperature distributions calculated.The increase in blood perfusion rates due to heating is incorporated into the model. Detailed transient temperature profiles in the finite element model are presented for various values of blood perfusion rates in the tumor and surrounding tissues. It is observed that the Annular Phased Array is effective in raising the temperature of the tumor to therapeutic values.

scholarly journals Integration of temperature sensors in polyimide-based thin-film electrode arrays

2015 ◽  
Vol 1 (1) ◽  
pp. 529-533 ◽  
Author(s):  
M. F. Porto Cruz ◽  
E. Fiedler ◽  
O. F. Cota Monjarás ◽  
T. Stieglitz
Keyword(s):  
Thin Film ◽  
Continuous Monitoring ◽  
Complete System ◽  
Wheatstone Bridge ◽  
Temperature Sensors ◽  
Implantable Devices ◽  
Tissue Temperature ◽  
Film Electrode ◽  
Readout System ◽  
Electrode Arrays

AbstractContinuous monitoring of the tissue temperature surrounding implantable devices could be of great advantage. The degree and duration of the immune activation in response to the implant, which is responsible for signal deterioration, could be inferred from the associated temperature raise and the heating caused by electrical or optogenetical stimulation could be accurately controlled. Within this work, a thin-film platinum RTD embedded in polyimide and a readout system based on the Wheatstone bridge configuration are presented. The RTD offers a sensitivity of 8.5 Ω· °C−1 and a precision of 4.1 Ω. The accuracy of the complete system calibrated for temperatures ranging from 34 to 41 °C lies between the classes A and B defined by the standard IEC 751, which correspond to tolerances of ±0.22 and ±0.48 °C at 37 °C, respectively.

ANALYTICAL SOLUTIONS OF NON-FOURIER PENNES AND CHEN–HOLMES EQUATIONS

2012 ◽  
Vol 05 (04) ◽  
pp. 1250022 ◽  
Author(s):  
WEIPING ZHU ◽  
FANGBAO TIAN ◽  
PENG RAN
Keyword(s):  
Heat Transfer ◽  
Analytical Solutions ◽  
Laplace Transformation ◽  
Solution Method ◽  
Thermal Relaxation ◽  
Blood Perfusion ◽  
Good Alternative ◽  
Tissue Temperature ◽  
Particular Solution ◽  
Insight Into

The analytical solutions of non-Fourier Pennes and Chen–Holmes equations are obtained using the Laplace transformation and particular solution method in the present paper. As an application, the effects of the thermal relaxation time τ, the blood perfusion wb, and the blood flow velocity v on the biological skin and inner tissue temperature T are studied in detail. The results obtained in this study provide a good alternative method to study the bio-heat and a biophysical insight into the understanding of the heat transfer in the biotissue.

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