The Experts below are selected from a list of 297 Experts worldwide ranked by ideXlab platform
Yong Huang - One of the best experts on this subject based on the ideXlab platform.
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Modeling of Thermoelastic Stress Wave in Laser-Assisted Cell Direct Writing
Journal of Manufacturing Science and Engineering, 2011Co-Authors: Wei Wang, Yafu Lin, Yong HuangAbstract:Laser-assisted cell direct-write technique has been a promising biomaterial direct-write method. For safe and reproducible cell direct writing, cell injury due to process-induced external stress must be understood in addition to biological property research. The objective of this study is to model the thermoelastic stress wave propagation inside the coating in laser-assisted cell direct writing when vaporization and/or optical breakdown of coating materials is/are not available. It is found that a bipolar pressure pair, with peak magnitudes on the order of 1 MPa or higher, has been developed within a finite thin coating medium. Shorter duration laser pulses lead to higher thermoelastic stresses. This study will help to understand the photomechanical stress and its relevance with biomaterial damage in laser-assisted cell direct writing.
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Laser-based direct-write techniques for cell printing
Biofabrication, 2010Co-Authors: Nathan R. Schiele, Yubing Xie, David T Corr, Nurazhani Abdul Raof, Yong Huang, Douglas B. ChriseyAbstract:Fabrication of cellular constructs with spatial control of cell location (+/-5 microm) is essential to the advancement of a wide range of applications including tissue engineering, stem cell and cancer research. Precise cell placement, especially of multiple cell types in co- or multi-cultures and in three dimensions, can enable research possibilities otherwise impossible, such as the cell-by-cell assembly of complex cellular constructs. Laser-based direct writing, a printing technique first utilized in electronics applications, has been adapted to transfer living cells and other biological materials (e.g., enzymes, proteins and bioceramics). Many different cell types have been printed using laser-based direct writing, and this technique offers significant improvements when compared to conventional cell patterning techniques. The predominance of work to date has not been in application of the technique, but rather focused on demonstrating the ability of direct writing to pattern living cells, in a spatially precise manner, while maintaining cellular viability. This paper reviews laser-based additive direct-write techniques for cell printing, and the various cell types successfully laser direct-written that have applications in tissue engineering, stem cell and cancer research are highlighted. A particular focus is paid to process dynamics modeling and process-induced cell injury during laser-based cell direct writing.
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Modeling of Bubble Expansion-Induced Cell Mechanical Profile in Laser-Assisted Cell Direct Writing
Journal of Manufacturing Science and Engineering, 2009Co-Authors: Wei Wang, Yong HuangAbstract:Cell damage due to the mechanical impact during laser-assisted cell direct writing has been observed and is a possible hurdle for broad applications of fragile cell direct writing. The objective of this study is to numerically investigate the bubble expansion-induced cell mechanical loading profile in laser-assisted cell direct writing. Some conclusions have been drawn as follows. The cell velocity increases initially and then smoothes out gradually with a constant ejection velocity. Both the cell acceleration and pressure can be very high at the beginning period of bubble expansion and then quickly approach zero in an oscillation manner. A high viscosity can lead to an observable velocity increment at the initial stage, but the ejection velocity decreases. The pressure magnitude decreases when the cell-bubble distance is large, and a larger initial pressure induces a larger cell pressure as expected. This study serves as a foundation to further investigate the cell damage mechanism in laser-assisted cell direct writing to improve the effectiveness and efficiency of cell direct writing techniques.
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Study of Impact-Induced Mechanical Effects in Cell Direct Writing Using Smooth Particle Hydrodynamic Method
Journal of Manufacturing Science and Engineering, 2008Co-Authors: Wei Wang, Yong Huang, Mica Grujicic, Douglas B. ChriseyAbstract:Biomaterial direct-write technologies have been receiving more and more attention as rapid prototyping innovations in the area of tissue engineering, regenerative medicine, and biosensor/actuator fabrication based on computer-aided designs. However, cell damage due to the mechanical impact during cell direct writing has been observed and is a possible hurdle for broad applications of fragile cell direct writing. The objective of this study is to investigate the impact-induced cell mechanical loading profile in cell landing in terms of stress, acceleration, and maximum shear strain component during cell direct writing using a mesh-free smooth particle hydrodynamic method. Such cell mechanical loading profile information can be used to understand and predict possible impact-induced cell damage. It is found that the cell membrane usually undergoes a relatively severe deformation and the cell mechanical loading profile is dependent on the cell droplet initial velocity and the substrate coating thickness. Two important impact processes may occur during cell direct writing: the first impact between the cell droplet and the substrate coating and the second impact between the cell and the substrate. It is concluded that the impact-induced cell damage depends not only on the magnitudes of stress, acceleration, and/or shear strain but also the loading history that a cell experiences.
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Modeling of Bubble Expansion-Induced Cell Mechanical Profile in Laser-Assisted Cell Direct Writing
ASME 2008 International Manufacturing Science and Engineering Conference Volume 2, 2008Co-Authors: Wei Wang, Yong HuangAbstract:Cell damage due to the mechanical impact during laser-assisted cell direct writing has been observed and is a possible hurdle for broad applications of fragile cell direct writing. The objective of this study is to numerically investigate the bubble expansion-induced cell mechanical loading profile in laser-assisted cell direct writing. Some conclusions have been drawn as follows. The cell velocity oscillates initially and then smoothes out gradually with a constant ejection velocity. Both the cell acceleration and pressure can be very high at the beginning period of bubble expansion and then quickly approaches zero in an oscillation manner. A high viscosity can lead to an observable velocity increment at the initial stage, but the ejection velocity decreases. The pressure magnitude decreases when the distance is large, and a larger initial pressure induces a larger cell pressure as expected. This study serves as a foundation to further investigate the cell damage mechanism in laser-assisted cell direct writing to improve the effectiveness and efficiency of cell direct writing techniques.Copyright © 2008 by ASME
J.a. Van Kan - One of the best experts on this subject based on the ideXlab platform.
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Proton beam writing
Materials Today, 2007Co-Authors: Frank Watt, Andrew A. Bettiol, Mark B. H. Breese, J.a. Van KanAbstract:Proton beam (p-beam) writing is a new Direct-Writing process that uses a focused beam of MeV protons to pattern resist material at nanodimensions. The process, although similar in many ways to direct writing using electrons, nevertheless offers some interesting and unique advantages. Protons, being more massive, have deeper penetration in materials while maintaining a straight path, enabling p-beam writing to fabricate three-dimensional, high aspect ratio structures with vertical, smooth sidewalls and low line-edge roughness. Calculations have also indicated that p-beam writing exhibits minimal proximity effects, since the secondary electrons induced in proton/electron collisions have low energy. A further advantage stems from the ability of protons to displace atoms while traversing material, thereby increasing localized damage especially at the end of range. P-beam writing produces resistive patterns at depth in Si, allowing patterning of selective regions with different optical properties as well as the removal of undamaged regions via electrochemical etching.
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Proton beam writing of passive polymer optical waveguides
Micromachining Technology for Micro-Optics and Nano-Optics II, 2004Co-Authors: Tze Chien Sum, J.a. Van Kan, Andrew A. Bettiol, Soma Venugopal Rao, A. Ramam, Frank WattAbstract:Proton beam writing is a new direct-write micromachining technique capable of producing 3-dimensional (3-D), high aspect ratio micro-structures with straight and smooth sidewalls. It uses a focused sub-micron beam of 2.0 MeV protons to direct-write on a suitable polymer, such as the photoresists: poly-methylmethacrylate (PMMA) and SU-8, a negative tone photoresist from MicroChem. In this paper, we report on the application of proton beam writing to fabricate low-loss passive polymer waveguide structures such as symmetric y-branching waveguides in SU-8. SU-8 channel waveguides are fabricated by first Direct-Writing the pattern using a proton beam and subsequently chemically developing the latent image formed. A UV-cured resin, Norland Optical Adhesive 88 (NOA-88) is used as the cladding layer. Being a direct-write technique, proton beam writing offers us great flexibility to fabricate waveguides of arbitrary patterns and this is an asset that can be applied to the rapid prototyping of optical circuits. With all its unique characteristics, proton beam writing is an excellent technique for waveguide fabrication.
Douglas B. Chrisey - One of the best experts on this subject based on the ideXlab platform.
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Laser-based direct-write techniques for cell printing
Biofabrication, 2010Co-Authors: Nathan R. Schiele, Yubing Xie, David T Corr, Nurazhani Abdul Raof, Yong Huang, Douglas B. ChriseyAbstract:Fabrication of cellular constructs with spatial control of cell location (+/-5 microm) is essential to the advancement of a wide range of applications including tissue engineering, stem cell and cancer research. Precise cell placement, especially of multiple cell types in co- or multi-cultures and in three dimensions, can enable research possibilities otherwise impossible, such as the cell-by-cell assembly of complex cellular constructs. Laser-based direct writing, a printing technique first utilized in electronics applications, has been adapted to transfer living cells and other biological materials (e.g., enzymes, proteins and bioceramics). Many different cell types have been printed using laser-based direct writing, and this technique offers significant improvements when compared to conventional cell patterning techniques. The predominance of work to date has not been in application of the technique, but rather focused on demonstrating the ability of direct writing to pattern living cells, in a spatially precise manner, while maintaining cellular viability. This paper reviews laser-based additive direct-write techniques for cell printing, and the various cell types successfully laser direct-written that have applications in tissue engineering, stem cell and cancer research are highlighted. A particular focus is paid to process dynamics modeling and process-induced cell injury during laser-based cell direct writing.
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Study of Impact-Induced Mechanical Effects in Cell Direct Writing Using Smooth Particle Hydrodynamic Method
Journal of Manufacturing Science and Engineering, 2008Co-Authors: Wei Wang, Yong Huang, Mica Grujicic, Douglas B. ChriseyAbstract:Biomaterial direct-write technologies have been receiving more and more attention as rapid prototyping innovations in the area of tissue engineering, regenerative medicine, and biosensor/actuator fabrication based on computer-aided designs. However, cell damage due to the mechanical impact during cell direct writing has been observed and is a possible hurdle for broad applications of fragile cell direct writing. The objective of this study is to investigate the impact-induced cell mechanical loading profile in cell landing in terms of stress, acceleration, and maximum shear strain component during cell direct writing using a mesh-free smooth particle hydrodynamic method. Such cell mechanical loading profile information can be used to understand and predict possible impact-induced cell damage. It is found that the cell membrane usually undergoes a relatively severe deformation and the cell mechanical loading profile is dependent on the cell droplet initial velocity and the substrate coating thickness. Two important impact processes may occur during cell direct writing: the first impact between the cell droplet and the substrate coating and the second impact between the cell and the substrate. It is concluded that the impact-induced cell damage depends not only on the magnitudes of stress, acceleration, and/or shear strain but also the loading history that a cell experiences.
Wei Wang - One of the best experts on this subject based on the ideXlab platform.
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Modeling of Thermoelastic Stress Wave in Laser-Assisted Cell Direct Writing
Journal of Manufacturing Science and Engineering, 2011Co-Authors: Wei Wang, Yafu Lin, Yong HuangAbstract:Laser-assisted cell direct-write technique has been a promising biomaterial direct-write method. For safe and reproducible cell direct writing, cell injury due to process-induced external stress must be understood in addition to biological property research. The objective of this study is to model the thermoelastic stress wave propagation inside the coating in laser-assisted cell direct writing when vaporization and/or optical breakdown of coating materials is/are not available. It is found that a bipolar pressure pair, with peak magnitudes on the order of 1 MPa or higher, has been developed within a finite thin coating medium. Shorter duration laser pulses lead to higher thermoelastic stresses. This study will help to understand the photomechanical stress and its relevance with biomaterial damage in laser-assisted cell direct writing.
-
Modeling of Bubble Expansion-Induced Cell Mechanical Profile in Laser-Assisted Cell Direct Writing
Journal of Manufacturing Science and Engineering, 2009Co-Authors: Wei Wang, Yong HuangAbstract:Cell damage due to the mechanical impact during laser-assisted cell direct writing has been observed and is a possible hurdle for broad applications of fragile cell direct writing. The objective of this study is to numerically investigate the bubble expansion-induced cell mechanical loading profile in laser-assisted cell direct writing. Some conclusions have been drawn as follows. The cell velocity increases initially and then smoothes out gradually with a constant ejection velocity. Both the cell acceleration and pressure can be very high at the beginning period of bubble expansion and then quickly approach zero in an oscillation manner. A high viscosity can lead to an observable velocity increment at the initial stage, but the ejection velocity decreases. The pressure magnitude decreases when the cell-bubble distance is large, and a larger initial pressure induces a larger cell pressure as expected. This study serves as a foundation to further investigate the cell damage mechanism in laser-assisted cell direct writing to improve the effectiveness and efficiency of cell direct writing techniques.
-
Study of Impact-Induced Mechanical Effects in Cell Direct Writing Using Smooth Particle Hydrodynamic Method
Journal of Manufacturing Science and Engineering, 2008Co-Authors: Wei Wang, Yong Huang, Mica Grujicic, Douglas B. ChriseyAbstract:Biomaterial direct-write technologies have been receiving more and more attention as rapid prototyping innovations in the area of tissue engineering, regenerative medicine, and biosensor/actuator fabrication based on computer-aided designs. However, cell damage due to the mechanical impact during cell direct writing has been observed and is a possible hurdle for broad applications of fragile cell direct writing. The objective of this study is to investigate the impact-induced cell mechanical loading profile in cell landing in terms of stress, acceleration, and maximum shear strain component during cell direct writing using a mesh-free smooth particle hydrodynamic method. Such cell mechanical loading profile information can be used to understand and predict possible impact-induced cell damage. It is found that the cell membrane usually undergoes a relatively severe deformation and the cell mechanical loading profile is dependent on the cell droplet initial velocity and the substrate coating thickness. Two important impact processes may occur during cell direct writing: the first impact between the cell droplet and the substrate coating and the second impact between the cell and the substrate. It is concluded that the impact-induced cell damage depends not only on the magnitudes of stress, acceleration, and/or shear strain but also the loading history that a cell experiences.
-
Modeling of Bubble Expansion-Induced Cell Mechanical Profile in Laser-Assisted Cell Direct Writing
ASME 2008 International Manufacturing Science and Engineering Conference Volume 2, 2008Co-Authors: Wei Wang, Yong HuangAbstract:Cell damage due to the mechanical impact during laser-assisted cell direct writing has been observed and is a possible hurdle for broad applications of fragile cell direct writing. The objective of this study is to numerically investigate the bubble expansion-induced cell mechanical loading profile in laser-assisted cell direct writing. Some conclusions have been drawn as follows. The cell velocity oscillates initially and then smoothes out gradually with a constant ejection velocity. Both the cell acceleration and pressure can be very high at the beginning period of bubble expansion and then quickly approaches zero in an oscillation manner. A high viscosity can lead to an observable velocity increment at the initial stage, but the ejection velocity decreases. The pressure magnitude decreases when the distance is large, and a larger initial pressure induces a larger cell pressure as expected. This study serves as a foundation to further investigate the cell damage mechanism in laser-assisted cell direct writing to improve the effectiveness and efficiency of cell direct writing techniques.Copyright © 2008 by ASME
Frank Watt - One of the best experts on this subject based on the ideXlab platform.
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Proton beam writing
Materials Today, 2007Co-Authors: Frank Watt, Andrew A. Bettiol, Mark B. H. Breese, J.a. Van KanAbstract:Proton beam (p-beam) writing is a new Direct-Writing process that uses a focused beam of MeV protons to pattern resist material at nanodimensions. The process, although similar in many ways to direct writing using electrons, nevertheless offers some interesting and unique advantages. Protons, being more massive, have deeper penetration in materials while maintaining a straight path, enabling p-beam writing to fabricate three-dimensional, high aspect ratio structures with vertical, smooth sidewalls and low line-edge roughness. Calculations have also indicated that p-beam writing exhibits minimal proximity effects, since the secondary electrons induced in proton/electron collisions have low energy. A further advantage stems from the ability of protons to displace atoms while traversing material, thereby increasing localized damage especially at the end of range. P-beam writing produces resistive patterns at depth in Si, allowing patterning of selective regions with different optical properties as well as the removal of undamaged regions via electrochemical etching.
-
Proton beam writing of passive polymer optical waveguides
Micromachining Technology for Micro-Optics and Nano-Optics II, 2004Co-Authors: Tze Chien Sum, J.a. Van Kan, Andrew A. Bettiol, Soma Venugopal Rao, A. Ramam, Frank WattAbstract:Proton beam writing is a new direct-write micromachining technique capable of producing 3-dimensional (3-D), high aspect ratio micro-structures with straight and smooth sidewalls. It uses a focused sub-micron beam of 2.0 MeV protons to direct-write on a suitable polymer, such as the photoresists: poly-methylmethacrylate (PMMA) and SU-8, a negative tone photoresist from MicroChem. In this paper, we report on the application of proton beam writing to fabricate low-loss passive polymer waveguide structures such as symmetric y-branching waveguides in SU-8. SU-8 channel waveguides are fabricated by first Direct-Writing the pattern using a proton beam and subsequently chemically developing the latent image formed. A UV-cured resin, Norland Optical Adhesive 88 (NOA-88) is used as the cladding layer. Being a direct-write technique, proton beam writing offers us great flexibility to fabricate waveguides of arbitrary patterns and this is an asset that can be applied to the rapid prototyping of optical circuits. With all its unique characteristics, proton beam writing is an excellent technique for waveguide fabrication.