Bulletin of the American Physical Society
69th Annual Meeting of the APS Division of Fluid Dynamics
Volume 61, Number 20
Sunday–Tuesday, November 20–22, 2016; Portland, Oregon
Session E39: Bio: Medical Devices |
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Chair: On Shun Pak, Santa Clara University Room: Portland Ballroom 256 |
Sunday, November 20, 2016 5:37PM - 5:50PM |
E39.00001: Influence of Slippery Pacemaker Leads on Lead-Induced Venous Occlusion Weiguang Yang, Sagar Bhatia, Dayna Obenauf, Max Resse, Mahdi Esmaily-Moghadam, Jeffrey Feinstein, On Shun Pak The use of medical devices such as pacemakers and implantable cardiac defibrillators have become commonplace to treat arrhythmias. Pacing leads with electrodes are used to send electrical pulses to the heart to treat either abnormally slow heart rates, or abnormal rhythms. Lead induced vessel occlusion, which is commonly seen after placement of pacemaker or ICD leads, may result in lead malfunction and/or SVC syndrome, and makes lead extraction difficult. The association between the anatomic locations at risk for thrombosis and regions of venous stasis have been reported previously. The computational studies reveal obvious flow stasis in the proximity of the leads, due to the no-slip boundary condition imposed on the lead surface. With the advent of recent technologies capable of creating slippery surfaces that can repel complex fluids including blood, we explore computationally how local flow structures may be altered in the regions around the leads when the no-slip boundary condition on the lead surface is relaxed using various slip lengths. The findings evaluate the possibility of mitigating risks of lead-induced thrombosis and occlusion by implementing novel surface conditions (i.e. theoretical coatings) on the leads. [Preview Abstract] |
Sunday, November 20, 2016 5:50PM - 6:03PM |
E39.00002: Computational device design: measuring esophageal distensibility using EndoFLIP Shashank Acharya, Wenjun Kou, Peter J. Kahrilas, John E. Pandolfino, Neelesh A. Patankar Characterizing the strength of sphincters in the human body is valuable from a diagnostic and surgical standpoint. We develop a numerical model for the EndoFLIP device (Endolumenal Functional Lumen Imaging Probe) that is crucial to the biomechanical study of the Lower Esophageal Sphincter (LES). The simulations demonstrate how the device operates \emph{in vivo}. From this model, we suggest additional use cases for the device that can give insight into the state of the esophageal wall. Currently, the device measures a single steady quantity (distensibility) that is calculated from pressure and area. Our analysis shows that by capturing and analyzing spatio-temporal pressure variations during peristalsis, the effectiveness of the contractions and health of the surrounding tissue can be quantified. Furthermore, there is an opportunity to validate tissue models by comparing dilation results with clinical data from the device. [Preview Abstract] |
Sunday, November 20, 2016 6:03PM - 6:16PM |
E39.00003: Prediction and optimization of the recovery rate in centrifugal separation of platelet-rich plasma (PRP). Linfeng Piao, Hyungmin Park, Chris Jo We present a theoretical model of the recovery rate of platelet and white blood cell in the process of centrifugal separation of platelet-rich plasma (PRP). For the practically used conditions in the field, the separation process is modeled as a one-dimensional particle sedimentation; a quasi-linear partial differential equation is derived based on the kinematic-wave theory. This is solved to determine the interface positions between supernatant-suspension and suspension-sediment, used to estimate the recovery rate of the plasma. While correcting the Brown's hypothesis (1989) claiming that the platelet recovery is linearly proportional to that of plasma, we propose a new correlation model for prediction of the platelet recovery, which is a function of the volume of whole blood, centrifugal acceleration and time. For a range of practical parameters, such as hematocrit, volume of whole blood and centrifugation (time and acceleration), the predicted recovery rate shows a good agreement with available clinical data. We propose that this model is further used to optimize the preparation method of PRP that satisfies the customized case. [Preview Abstract] |
Sunday, November 20, 2016 6:16PM - 6:29PM |
E39.00004: Multiscale modeling of a Chemofilter device for filtering chemotherapy toxins from blood Nazanin Maani, Saman Beyhaghi, Daryl Yee, Micheal Nosonovsky, Julia Greer, Steven Hetts, Vitaliy Rayz \textbf{Purpose}: Chemotherapy drugs injected intra-arterially to treat cancer can cause systemic toxic effects. A catheter-based Chemofilter device, temporarily deployed in a vein during the procedure can filter excessive drug from the blood thus reducing chemotherapy side-effects. CFD modeling is used to design the membrane of the Chemofilter in order to optimize its hemodynamic performance. \textbf{Methods}: Multiscale approach is used to model blood flow through the Chemofilter. The toxins bind to the Chemofilter's membrane formed by a lattice of numerous micro cells deployed in a blood vessel of much larger size. A detailed model of the flow through a 2x2 microcell matrix with periodic boundary conditions is used to determine the permeability of the membrane. The results are used to simulate the flow through the whole device modeled as a uniform porous membrane. The finite-volume solver Fluent is used to obtain the numerical solution. \textbf{Results}: The micro cell matrix has a porosity of 0.92. The pressure drop across the resolved microcells was found to be 630 Pa, resulting in the permeability of 6.21 x10$^{\mathrm{-11}}$ m$^{\mathrm{2}}$ in the normal direction. These values were used to optimize the device geometry in order to increase the contact area of the membrane, while minimizing its obstruction to the flow. [Preview Abstract] |
Sunday, November 20, 2016 6:29PM - 6:42PM |
E39.00005: Stochastic Model of Clogging in a Microfluidic Cell Sorter Thomas Fai, Chris Rycroft Microfluidic devices for sorting cells by deformability show promise for various medical purposes, e.g. detecting sickle cell anemia and circulating tumor cells. One class of such devices consists of a two-dimensional array of narrow channels, each column containing several identical channels in parallel. Cells are driven through the device by an applied pressure or flow rate. Such devices allows for many cells to be sorted simultaneously, but cells eventually clog individual channels and change the device properties in an unpredictable manner. In this talk, we propose a stochastic model for the failure of such microfluidic devices by clogging and present preliminary theoretical and computational results. The model can be recast as an ODE that exhibits finite time blow-up under certain conditions. The failure time distribution is investigated analytically in certain limiting cases, and more realistic versions of the model are solved by computer simulation. [Preview Abstract] |
Sunday, November 20, 2016 6:42PM - 6:55PM |
E39.00006: An application of the focused liquid jet: needle free drug injection system Akihito Kiyama, Chihiro Katsuta, Sennosuke Kawamoto, Nanami Endo, Akane Tanaka, Yoshiyuki Tagawa Recently, a focused liquid jet draws great attention since it can be applied to various applications (e. g. Ink jet printing, medical devices). In our research, in order to discuss its applicability for a needle-free drug injection system, we shoot a focused liquid jet (Tagawa, et al., Phys. Rev. X, 2012) to an animal skin with very high-speed. Previously, the penetration of this jet into a gelatin and an artificial skin has been performed in order to model of the jet penetration process (Tagawa, et al., Lab. Chip., 2013). However, experiment for jet injection into the animal skin has not been conducted yet. In this presentation, we inject ink as the liquid jet into the skin of the hairless rat. We observe the top/back view and the cross-sectional view of the injected (ink-stained) skin. We capture the stained area of the skin in order to find characteristics of the jet penetration. We discuss the criteria for the jet penetration into the skin. [Preview Abstract] |
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