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Material Characterization Method Development: From Education to Design Optimization

C. Morgan[1], N. Kenkare[1], M. Williams[2], A. Peterson[2], and D. Williams[2]
[1]Alcon Eye Care Division of Novartis R&D, Duluth, GA
[2]Alcon Eye Care Division of Novartis R&D and Georgia Institute of Technology Co-op Program, GA

Introduction of silicone hydrogel contact lens materials provided products of unprecedented capability to deliver oxygen to the eye during wear. One additional material characteristic of interest is the material’s permeability to ions. This paper discusses descriptive tools and optimization of an impedance method of characterizing ion permeability. A physical model of conductive paper with ...

Modeling Inertial Focusing in Straight and Curved Microfluidic Channels

J. Martel[1], N. Elabbasi[2], D. Quinn[2], J. Bergstrom[2], M. Toner[1]
[1]BioMEMS Resource Center, Massachusetts General Hospital, Boston, MA, USA
[2]Veryst Engineering, Needham, MA, USA

Inertial focusing is a promising microfluidic technique for separating and concentrating cells of interest, processes routinely utilized in many medical procedures. This phenomenon is characterized by suspended particles in a flow spontaneously migrating across streamlines to equilibrium positions within a channel cross-section. We developed CFD models in COMSOL Multiphysics® to predict the ...

Numerical Prediction of Particle Dynamics Within a Cytometer. Application to Counting and Sizing by Impendance Measurement

D. Isèbe[1]
[1]HORIBA Medical, Montpellier, France

This paper describes how to numerically tackle the problem of counting and sizing particles by impedance measurement in an orifice–electrode system. The model simulate the particle dynamics submitted to strong hydrodynamic stresses through a microorifice and compute the voltage pulses generated by the modification of the inner dielectric medium. This FSI problem is solved on a moving mesh by ...

Multiphysics Model of the NovaSure Endometrial Ablation Procedure

G.T. Martin[1], and L. Angelone[2]
[1]Hologic, Inc., Bedford, Massachusetts, USA
[2]Massachusetts General Hospital, Harvard Medical School, Marlborough, Massachusetts, USA

The NovaSure Endometrial Ablation System® is designed to remove the endometrial lining in the uterine cavity of women who suffer from menorrhagia. The NovaSure disposable device consists of a 2-pole, 4 electrode array that is inserted into the uterine cavity and deployed. We have developed a COMSOL Multiphysics model of the NovaSure ablation process. The model utilized COMSOL Multiphysics ...

Finite Element Analysis of Muscular Contractions from DC Pulses in the Liver

G. Long, D. Plescia, and P. Shires
Ethicon Endo-Surgery, Cincinnati, OH, USA

Thermal ablation of malignant tumors has been conducted in patients who are not candidates for surgery for more than ten years. Recently it has been shown that low energy DC pulses can cause cell necrosis. An undesirable characteristic of DC pulses in-vivo is the stimulation of skeletal muscle. The intensity of the contraction depends in part on the duration and height of the pulse. Through the ...

Multiphysics Modeling of Cellular Arrays Using Periodic Minimal Surfaces – A Drug and Gene Delivery Application

J.I. Rey, A.J. Llewellyn, R.J. Connolly, J.P. Jimenez, A.M. Hoff, and R.A. Gilbert
University of South Florida, Tampa, FL, USA

Minimal surfaces are found in nature from crystalline structures to biological nano and micro structures such as biomembranes, and osseous formations in sea urchin. An application to electrically mediated drug and gene delivery is presented. Periodic level surfaces which approximate minimal surfaces are used to generate a geometric representation of tissue. A method to create such structures ...

Actively Controlled Ionic Current Gating In Nanopores

G. Zhang[1], S. Bearden[1]
[1]Clemson University, Clemson, SC, USA

It is necessary to understand and control nanopore behavior in order to develop biosensors for a variety of applications including DNA sequencing. The fluidics of nanopore devices we fabricated exhibits a range of interesting phenomena, such as enhanced conductance and current rectification. By electrically biasing nanopores, we were able to actively control the nanopore conductance in real time ...

Modeling Bacterial Transport and Removal in a Constructed Wetland System

E. Engström, B. Balfors, and R. Thunvik
Royal Institute of Technology, Stockholm, Sweden

In this study we evaluate transport, retention and subsistence of Escherichia coli (E. coli), a common fecal indicator bacteria, in a model (2x1m) of a constructed wetland. Transport occurs in the unsaturated and saturated zone. Inactivation is accounted for as a kinetic first-order process. Retention is assumed to be dominated by solid-air-water interface straining and is modeled with a kinetic ...

An Assessment of the Suitability of the Body and Adult Head Coils for Transmission during Paediatric Magnetic Resonance Imaging

G.R. Cook[1], M.J. Graves[1], F.J. Robb[2], D.J. Lomas[1]
[1]Department of Radiology, University of Cambridge, Cambridge, United Kingdom
[2]General Electric Healthcare Coils, Aurora, Ohio, USA

MRI offers many advantages over other modalities and its lack of ionizing radiation is important for children, but can be limited by the radio-frequency (RF) coils available. This work calculates Specific Absorption Rate (SAR) and homogeneity of the RF transmit field (B1+) when imaging infants in adult coils. Two birdcage-type coils were loaded by a tissue model and their B1+ homogeneities ...

Simulation of Transport of Lipophilic Compounds in Complex Cell Geometry

Q.A. Chaudhry[1], M. Hanke[1], and R. Morgenstern[2]
[1]School of Computer Science and Communication, Royal Institute of Technology, Stockholm, Sweden
[2]Karolinska Institutet, Stockholm, Sweden

The mathematical modeling of the diffusion and reaction of toxic compounds in mammalian cells is tough task due to their very complex geometry. The heterogeneity of the cell, particularly the cytoplasm, and the variation of the cellular architecture, greatly affects the behavior of these toxic compounds. Homogenization techniques have been implemented for the numerical treatment of the model. ...