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Research Papers

Engineered Tissue Scaffolds With Variational Porous Architecture

[+] Author and Article Information
A. K. M. B. Khoda, Ibrahim T. Ozbolat

Department of Industrial Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260

Bahattin Koc

Faculty of Engineering and Natural Sciences, Sabanci University, Istanbul 34956, Turkey; Department of Industrial Engineering, University at Buffalo, State University of New York, Buffalo, NY 14260bahattinkoc@sabanciuniv.edu

J Biomech Eng 133(1), 011001 (Dec 22, 2010) (12 pages) doi:10.1115/1.4002933 History: Received January 14, 2010; Revised October 19, 2010; Posted November 02, 2010; Published December 22, 2010; Online December 22, 2010

This paper presents a novel computer-aided modeling of 3D tissue scaffolds with a controlled internal architecture. The complex internal architecture of scaffolds is biomimetically modeled with controlled micro-architecture to satisfy different and sometimes conflicting functional requirements. A functionally gradient porosity function is used to vary the porosity of the designed scaffolds spatially to mimic the functionality of tissues or organs. The three-dimensional porous structures of the scaffold are geometrically partition into functionally uniform porosity regions with a novel offsetting operation technique described in this paper. After determining the functionally uniform porous regions, an optimized deposition-path planning is presented to generate the variational internal porosity architecture with enhanced control of interconnected channel networks and continuous filament deposition. The presented methods are implemented, and illustrative examples are presented in this paper. Moreover, a sample optimized tool path for each example is fabricated layer-by-layer using a micronozzle biomaterial deposition system.

Copyright © 2011 by American Society of Mechanical Engineers
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Figures

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Figure 1

Roadmap of proposed approach for building a complex scaffold with tailored geometry

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Figure 2

(a) Porosity distribution and (b) top view of a slice and its related functionally uniform porous regions

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Figure 3

Offsetting surfaces by offsetting (a) the facet create intersection intersecting loop, (b) the vertices to inward direction by using the averaged normal vector method, (c) the facet create gaps and changing the original shape of objects, and (d) the vertices to outward direction by using the averaged normal vector method

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Figure 4

Self-intersections and loops forming and their elimination

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Figure 5

Sample fluid flow through an open channel for a random region with filaments at (a) aligned position with equal connectivity angles (α1=α2=θ) and at (b) misaligned position with different connectivity angles (α1>θ and α2<θ)

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Figure 6

Continuous filament deposition (a) with number of filaments in region k+1 is odd and (b) with number of filaments in region k+1 is even and an additional filament to make it odd

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Figure 7

Locating and assigning filaments to optimize connectivity between regions

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Figure 8

Solid model and the STL model of the vertebrae: (a) perspective view of STL and shaded model of vertebrae and (b) sliced contour along with three distinct porosity regions of vertebrae

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Figure 9

Loop detection and elimination

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Figure 10

Computer model of designed optimum tool path for two consecutive vertebra slices: (a) porosity function, (b) designed optimum tool path, and (c) zoomed section with defined porosity

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Figure 11

Solid model and the STL model of the aorta: (a) perspective view of STL model and (b) surface model of aorta (sliced contour along with three distinct porosity region)

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Figure 12

Computer model of designed optimum tool path for two consecutive aorta slices: (a) porosity function, (b) designed optimum tool path, and (c) zoomed section with defined porosity label

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Figure 13

Solid model and the STL model of the femur: (a) perspective view of STL and shaded model of vertebrae and (b) sliced contour along with three distinct porosity region of femur

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Figure 14

Computer model of designed optimum tool path for two consecutive femur slices: (a) porosity function, (b) designed optimum tool path, and (c) zoomed section with defined porosity

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Figure 15

Fabricated slices with the continuous and interconnected filament of 150 μm diameter: (a) two consecutive fabricated femur slices with five different porosity regions of 90%, 85.6%, 83.2%, 81.2%, and 76.4%; (b) zoomed view for continuous and interconnected tool path, (c) the 3D model of the femur with 16 slices; (d) two consecutive fabricated aorta slices with three different porosity region of 86.2, 82.1, and 78.6; (e) zoomed view for continuous and interconnected tool path; (f) the 3D model of the aorta with 16 slices; (g) two consecutive fabricated vertebra slices with five different porosity regions of 84.6%, 83.6%, 79.3%, 78.1%, and 76.2%; (h) zoomed view for continuous and interconnected tool path; and (i) the 3D model of the vertebra with 18 slices

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