Design Optimization of Scaffold Microstructures Using Wall Shear Stress Criterion Towards Regulated Flow-Induced Erosion

2011 ◽  
Vol 133 (8) ◽  
Author(s):  
Yuhang Chen ◽  
Michiel Schellekens ◽  
Shiwei Zhou ◽  
Joseph Cadman ◽  
Wei Li ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Design Optimization ◽  
Cellular Response ◽  
Polymer Scaffold ◽  
Erosion Process ◽  
Stress Criterion ◽  
A Cell ◽  
Wall Shear ◽  
Biomechanical Features

Tissue scaffolds aim to provide a cell-friendly biomechanical environment for facilitating cell growth. Existing studies have shown significant demands for generating a certain level of wall shear stress (WSS) on scaffold microstructural surfaces for promoting cellular response and attachment efficacy. Recently, its role in shear-induced erosion of polymer scaffold has also drawn increasing attention. This paper proposes a bi-directional evolutionary structural optimization (BESO) approach for design of scaffold microstructure in terms of the WSS uniformity criterion, by downgrading highly-stressed solid elements into fluidic elements and/or upgrading lowly-stressed fluidic elements into solid elements. In addition to this, a computational model is presented to simulate shear-induced erosion process. The effective stiffness and permeability of initial and optimized scaffold microstructures are characterized by the finite element based homogenization technique to quantify the variations of mechanical properties of scaffold during erosion. The illustrative examples show that a uniform WSS is achieved within the optimized scaffold microstructures, and their architectural and biomechanical features are maintained for a longer lifetime during shear-induced erosion process. This study provides a mathematical means to the design optimization of cellular biomaterials in terms of the WSS criterion towards controllable shear-induced erosion.

Multi-Axial Mechanical Stimulation of HUVECs Demonstrates That Combined Loading is not Equivalent to the Superposition of Individual Wall Shear Stress and Tensile Hoop Stress Components

2009 ◽  
Vol 131 (8) ◽  
Author(s):  
Liam T. Breen ◽  
Peter E. McHugh ◽  
Bruce P. Murphy
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Cellular Response ◽  
Umbilical Vein ◽  
Combined Loading ◽  
Hoop Strain ◽  
Hemodynamic Forces ◽  
Testing Period ◽  
Wall Shear

Over the past 25 years, many laboratory based bioreactors have been used to study the cellular response to hemodynamic forces. The vast majority of these studies have focused on the effect of a single isolated hemodynamic force, generally consisting of a wall shear stress (WSS) or a tensile hoop strain (THS). However, investigating the cellular response to a single isolated force does not accurately represent the true in vivo situation, where a number of forces are acting simultaneously. This study used a novel bioreactor to investigate the cellular response of human umbilical vein endothelial cells (HUVECs) exposed to a combination of steady WSS and a range of cyclic THS. HUVECs exposed to a range of cyclic THS (0–12%), over a 12 h testing period, expressed an upregulation of both ICAM-1 and VCAM-1. HUVECs exposed to a steady WSS (0 dynes/cm2 and 25 dynes/cm2), over a 12 h testing period, also exhibited an ICAM-1 upregulation but a VCAM-1 downregulation, where the greatest level of WSS stimulus resulted in the largest upregulation and downregulation of ICAM-1 and VCAM-1, respectively. A number of HUVEC samples were exposed to a high steady WSS (25 dynes/cm2) combined with a range of cyclic THS (0–4%, 0–8%, and 0–12%) for a 12 h testing period. The initial ICAM-1 upregulation, due to the WSS alone, was downregulated with the addition of a cyclic THS. It was observed that the largest THS (0–12%) had the greatest reducing effect on the ICAM-1 upregulation. Similarly, the initial VCAM-1 downregulation, due to the high steady WSS alone, was further downregulated with the addition of a cyclic THS. A similar outcome was observed when HUVEC samples were exposed to a low steady WSS combined with a range of cyclic THS. However, the addition of a THS to the low WSS did not result in an expected ICAM-1 downregulation. In fact, it resulted in a trend of unexpected ICAM-1 upregulation. The unexpected cellular response to the combination of a steady WSS and a cyclic THS demonstrates that such a response could not be determined by simply superimposing the cellular responses exhibited by ECs exposed to a steady WSS and a cyclic THS that were applied in isolation.

scholarly journals Design Optimization of Vena Cava Filters: An Application to Dual Filtration Devices

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
Michael A. Singer ◽  
Stephen L. Wang ◽  
Darin P. Diachin
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Inferior Vena Cava ◽  
Objective Function ◽  
Design Optimization ◽  
Inferior Vena ◽  
Vena Cava ◽  
Shear Stresses ◽  
Vena Cava Filters ◽  
Wall Shear

Pulmonary embolism (PE) is a significant medical problem that results in over 300,000 fatalities per year. A common preventative treatment for PE is the insertion of a metallic filter into the inferior vena cava that traps thrombi before they reach the lungs. The goal of this work is to use methods of mathematical modeling and design optimization to determine the configuration of trapped thrombi that minimizes the hemodynamic disruption. The resulting configuration has implications for constructing an optimally designed vena cava filter. Computational fluid dynamics is coupled with a nonlinear optimization algorithm to determine the optimal configuration of a trapped model thrombus in the inferior vena cava. The location and shape of the thrombus are parametrized, and an objective function, based on wall shear stresses, determines the worthiness of a given configuration. The methods are fully automated and demonstrate the capabilities of a design optimization framework that is broadly applicable. Changes to thrombus location and shape alter the velocity contours and wall shear stress profiles significantly. For vena cava filters that trap two thrombi simultaneously, the undesirable flow dynamics past one thrombus can be mitigated by leveraging the flow past the other thrombus. Streamlining the shape of the thrombus trapped along the cava wall reduces the disruption to the flow but increases the area exposed to low wall shear stress. Computer-based design optimization is a useful tool for developing vena cava filters. Characterizing and parametrizing the design requirements and constraints is essential for constructing devices that address clinical complications. In addition, formulating a well-defined objective function that quantifies clinical risks and benefits is needed for designing devices that are clinically viable.

Design of cellular porous biomaterials for wall shear stress criterion

2010 ◽  
Vol 107 (4) ◽  
pp. 737-746 ◽  
Author(s):  
Yuhang Chen ◽  
Shiwei Zhou ◽  
Joseph Cadman ◽  
Qing Li
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Stress Criterion ◽  
Wall Shear ◽  
Porous Biomaterials

Correction: Development of a Two-Dimensional Wall Shear Stress Sensor for Wind Tunnel Applications

2019 ◽  
Author(s):  
Brett Freidkes ◽  
David A. Mills ◽  
Casey Keane ◽  
Lawrence S. Ukeiley ◽  
Mark Sheplak
Keyword(s):  
Shear Stress ◽  
Wind Tunnel ◽  
Wall Shear Stress ◽  
Two Dimensional ◽  
Stress Sensor ◽  
Shear Stress Sensor ◽  
Wall Shear

Basic study on estimation method of wall shear stress in common carotid artery using blood flow imaging

2020 ◽  
Vol 59 (SK) ◽  
pp. SKKE16 ◽  
Author(s):  
Ryo Nagaoka ◽  
Kazuma Ishikawa ◽  
Michiya Mozumi ◽  
Magnus Cinthio ◽  
Hideyuki Hasegawa
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Carotid Artery ◽  
Wall Shear Stress ◽  
Common Carotid Artery ◽  
Estimation Method ◽  
Flow Imaging ◽  
Basic Study ◽  
Blood Flow Imaging ◽  
Wall Shear
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