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Research Papers

Modeling and Simulation of a Selective Laser Foaming Process for Fabrication of Microliter Tissue Engineering Scaffolds

[+] Author and Article Information
JinGyu Ock

Department of Mechanical Engineering,
The University of Texas at Austin,
Austin, TX 78712

Wei Li

Department of Mechanical Engineering,
The University of Texas at Austin,
Austin, TX 78712
e-mail: weiwli@austin.utexas.edu

1Corresponding author.

Manuscript received February 14, 2017; final manuscript received July 18, 2017; published online September 13, 2017. Assoc. Editor: Donggang Yao.

J. Manuf. Sci. Eng 139(11), 111016 (Sep 13, 2017) (8 pages) Paper No: MANU-17-1097; doi: 10.1115/1.4037425 History: Received February 14, 2017; Revised July 18, 2017

Selective laser foaming is a novel process that combines solid-state foaming and laser ablation to fabricate an array of microliter tissue engineering scaffolds on a polymeric chip for biomedical applications. In this study, a finite element analysis (FEA) model is developed to investigate the effect of laser processing parameters. Experimental results with biodegradable polylactic acid (PLA) were used for validation. It is found that foaming always occurs before ablation, and once it occurs, the temperature increases dramatically due to an enhanced laser absorption effect of the porous structure. The geometry of the fabricated scaffolds can be controlled by laser parameters. While the depth of scaffolds can be controlled by laser power and lasing time, the diameter is more effectively controlled by the laser power. The model developed in this study can be used to optimize and control the selective foaming process.

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Figures

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Fig. 1

A schematic of the selective laser foaming process: (a) gas saturation and (b) laser irradiation [1]

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Fig. 2

Geometry and meshing of the FEA model. (1)(4) denote the model boundaries.

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Fig. 3

Solution procedure of the finite element model

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Fig. 4

Comparison between experimental data and modeling results: (a) cross-sectional SEM image of laser ablated and unfoamed sample, (b) simulation result of the unfoamed sample, (c) cross-sectional SEM image of laser foamed and ablated sample, and (d) predicted temperature distribution of the foamed sample

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Fig. 5

Comparison of predicted and experimental results. Ablation and foaming profiles are shown by the upper and lower curves, respectively. Scale bars are all 1 mm.

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Fig. 6

The volume of foamed region as a function of laser energy. Each graph has different laser power setup: (a) 2.0 W, (b) 4.6 W, (c) 7.7 W, and (d) 10.3 W.

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Fig. 7

Temperature distribution on the top surface of a saturated sample at a laser power of 7.7 W

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Fig. 8

Depth of ablated region as a function of lasing time at different laser powers. Hundred percentage indicates the maximum laser power.

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Fig. 9

Diameter of ablated region as a function of lasing time with different laser powers

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Fig. 10

Depth of foamed region as a function of lasing time at different laser powers

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Fig. 11

Diameter of foamed region as a function of lasing time at different laser powers

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Fig. 12

Normalized laser power density along with radial direction of the laser beam

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