Publications
1.
Kang, Sung Hoon; Wu, Ning; Grinthal, Alison; Aizenberg, Joanna
Meniscus Lithography: Evaporation-Induced Self-Organization of Pillar Arrays into Moiré Patterns Journal Article
In: Physical Review Letters, vol. 107, pp. 177802, 2011, (Selected as Physical Review Letters Editors’ Suggestion and Highlighted in Physics Today and Physics Synopsis. ).
@article{Kang2011,
title = {Meniscus Lithography: Evaporation-Induced Self-Organization of Pillar Arrays into Moiré Patterns},
author = {Sung Hoon Kang and Ning Wu and Alison Grinthal and Joanna Aizenberg},
url = {http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.107.177802},
year = {2011},
date = {2011-10-20},
journal = {Physical Review Letters},
volume = {107},
pages = {177802},
abstract = {We demonstrate a self-organizing system that generates patterns by dynamic feedback: two periodic surfaces collectively structure an intervening liquid sandwiched between them, which then reconfigures the original surface features into moiré patterns as it evaporates. Like the conventional moiré phenomenon, the patterns are deterministic and tunable by mismatch angle, yet additional behaviors—chirality from achiral starting motifs and preservation of the patterns after the surfaces are separated—emerge uniquely from the feedback process. Patterning menisci based on this principle provides a simple, scalable approach for making a series of complex, long-range-ordered structures.},
note = {Selected as Physical Review Letters Editors’ Suggestion and Highlighted in Physics Today and Physics Synopsis. },
keywords = {},
pubstate = {published},
tppubtype = {article}
}
We demonstrate a self-organizing system that generates patterns by dynamic feedback: two periodic surfaces collectively structure an intervening liquid sandwiched between them, which then reconfigures the original surface features into moiré patterns as it evaporates. Like the conventional moiré phenomenon, the patterns are deterministic and tunable by mismatch angle, yet additional behaviors—chirality from achiral starting motifs and preservation of the patterns after the surfaces are separated—emerge uniquely from the feedback process. Patterning menisci based on this principle provides a simple, scalable approach for making a series of complex, long-range-ordered structures.
2.
Seminara, Agnese; Pokroy, Boaz; Kang, Sung Hoon; Brenner, Michael P.; Aizenberg, Joanna
On the Mechanism of Nanostructure Movement under Electron Beam and Its Application in Patterning Journal Article
In: Physical Review B, vol. 83, pp. 235438, 2011.
@article{Seminara2011,
title = {On the Mechanism of Nanostructure Movement under Electron Beam and Its Application in Patterning},
author = {Agnese Seminara and Boaz Pokroy and Sung Hoon Kang and Michael P. Brenner and Joanna Aizenberg},
url = {http://journals.aps.org/prb/abstract/10.1103/PhysRevB.83.235438},
year = {2011},
date = {2011-06-30},
journal = {Physical Review B},
volume = {83},
pages = {235438},
abstract = {In electron microscopy, the motion of the sample features due to the interaction with the electron beam has been traditionally regarded as a detrimental effect. Uncontrolled feature displacement produces artifacts both in imaging and patterning, limiting the resolution and distorting precise nanoscale patterns. The mechanism of such motion remains largely unclear. We present an experimental study of e-beam-induced nanopost movement and offer a mechanistic theoretical model that quantitatively explains the physical phenomenon. We propose that e-beam bombardment produces an uneven distribution of electrons in the sample, and the resulting electrostatic interactions provide forces and torques sufficient to bend the nanoposts. We compare the theoretical predictions with a series of controlled experiments that support our model. We take advantage of this theoretical understanding to demonstrate how this generally undesirable effect can be turned into an unconventional e-beam writing technique to generate pseudo-three-dimensional structures.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
In electron microscopy, the motion of the sample features due to the interaction with the electron beam has been traditionally regarded as a detrimental effect. Uncontrolled feature displacement produces artifacts both in imaging and patterning, limiting the resolution and distorting precise nanoscale patterns. The mechanism of such motion remains largely unclear. We present an experimental study of e-beam-induced nanopost movement and offer a mechanistic theoretical model that quantitatively explains the physical phenomenon. We propose that e-beam bombardment produces an uneven distribution of electrons in the sample, and the resulting electrostatic interactions provide forces and torques sufficient to bend the nanoposts. We compare the theoretical predictions with a series of controlled experiments that support our model. We take advantage of this theoretical understanding to demonstrate how this generally undesirable effect can be turned into an unconventional e-beam writing technique to generate pseudo-three-dimensional structures.
3.
Kang, Sung Hoon; Pokroy, Boaz; Mahadevan, L.; Aizenberg, Joanna
Control of Shape and Size of Nanopillar Assembly by Adhesion-Mediated Elastocapillary Interaction Journal Article
In: ACS Nano, vol. 4, pp. 6323–6331, 2010, (Featured on the cover and highlighted in the issue.).
@article{Kang2010,
title = {Control of Shape and Size of Nanopillar Assembly by Adhesion-Mediated Elastocapillary Interaction},
author = {Sung Hoon Kang and Boaz Pokroy and L. Mahadevan and Joanna Aizenberg},
url = {http://pubs.acs.org/doi/abs/10.1021/nn102260t},
year = {2010},
date = {2010-11-01},
journal = {ACS Nano},
volume = {4},
pages = {6323–6331},
abstract = {Control of self-organization of nanofibers into regular clusters upon evaporation-induced assembly is receiving increasing attention due to the potential importance of this process in a range of applications including particle trapping, adhesives, and structural color. Here we present a comprehensive study of this phenomenon using a periodic array of polymeric nanopillars with tunable parameters as a model system to study how geometry, mechanical properties, as well as surface properties influence capillary-induced self-organization. In particular, we show that varying the parameters of the building blocks of self-assembly provides us with a simple means of controlling the size, chirality, and anisotropy of complex structures. We observe that chiral assemblies can be generated within a narrow window for each parameter even in the absence of chiral building blocks or a chiral environment. Furthermore, introducing anisotropy in the building blocks provides a way to control both the chirality and the size of the assembly. While capillary-induced self-assembly has been studied and modeled as a quasi-static process involving the competition between only capillary and elastic forces, our results unequivocally show that both adhesion and kinetics are equally important in determining the final assembly. Our findings provide insight into how multiple parameters work together in capillary-induced self-assembly and provide us with a diverse set of options for fabricating a variety of nanostructures by self-assembly.},
note = {Featured on the cover and highlighted in the issue.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Control of self-organization of nanofibers into regular clusters upon evaporation-induced assembly is receiving increasing attention due to the potential importance of this process in a range of applications including particle trapping, adhesives, and structural color. Here we present a comprehensive study of this phenomenon using a periodic array of polymeric nanopillars with tunable parameters as a model system to study how geometry, mechanical properties, as well as surface properties influence capillary-induced self-organization. In particular, we show that varying the parameters of the building blocks of self-assembly provides us with a simple means of controlling the size, chirality, and anisotropy of complex structures. We observe that chiral assemblies can be generated within a narrow window for each parameter even in the absence of chiral building blocks or a chiral environment. Furthermore, introducing anisotropy in the building blocks provides a way to control both the chirality and the size of the assembly. While capillary-induced self-assembly has been studied and modeled as a quasi-static process involving the competition between only capillary and elastic forces, our results unequivocally show that both adhesion and kinetics are equally important in determining the final assembly. Our findings provide insight into how multiple parameters work together in capillary-induced self-assembly and provide us with a diverse set of options for fabricating a variety of nanostructures by self-assembly.
4.
Pokroy, Boaz; Kang, Sung Hoon; Mahadevan, L.; Aizenberg, Joanna
Self-Organization of a Mesoscale Bristle into Ordered, Hierarchical Helical Assemblies Journal Article
In: Science, vol. 323, pp. 237-240, 2009, (Highlighted in the issue, and various media including New York Times, NPR, Discovery, AAAS EurekAlert, C&EN, Technology Review, IEEE Spectrum, Science Daily, and New Scientist. ).
@article{Pokroy2009,
title = {Self-Organization of a Mesoscale Bristle into Ordered, Hierarchical Helical Assemblies},
author = {Boaz Pokroy and Sung Hoon Kang and L. Mahadevan and Joanna Aizenberg
},
url = {http://www.sciencemag.org/content/323/5911/237.short},
year = {2009},
date = {2009-01-09},
journal = {Science},
volume = {323},
pages = {237-240},
abstract = {Mesoscale hierarchical helical structures with diverse functions are abundant in nature. Here we show how spontaneous helicity can be induced in a synthetic polymeric nanobristle assembling in an evaporating liquid. We use a simple theoretical model to characterize the geometry, stiffness, and surface properties of the pillars that favor the adhesive self-organization of bundles with pillars wound around each other. The process can be controlled to yield highly ordered helical clusters with a unique structural hierarchy that arises from the sequential assembly of self-similar coiled building blocks over multiple length scales. We demonstrate their function in the context of self-assembly into previously unseen structures with uniform, periodic patterns and controlled handedness and as an efficient particle-trapping and adhesive system. },
note = {Highlighted in the issue, and various media including New York Times, NPR, Discovery, AAAS EurekAlert, C&EN, Technology Review, IEEE Spectrum, Science Daily, and New Scientist. },
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Mesoscale hierarchical helical structures with diverse functions are abundant in nature. Here we show how spontaneous helicity can be induced in a synthetic polymeric nanobristle assembling in an evaporating liquid. We use a simple theoretical model to characterize the geometry, stiffness, and surface properties of the pillars that favor the adhesive self-organization of bundles with pillars wound around each other. The process can be controlled to yield highly ordered helical clusters with a unique structural hierarchy that arises from the sequential assembly of self-similar coiled building blocks over multiple length scales. We demonstrate their function in the context of self-assembly into previously unseen structures with uniform, periodic patterns and controlled handedness and as an efficient particle-trapping and adhesive system.
Note: Send e-mail to Prof. Kang at [email protected] if you need a pdf file of the papers below.
2011
Kang, Sung Hoon; Wu, Ning; Grinthal, Alison; Aizenberg, Joanna
Meniscus Lithography: Evaporation-Induced Self-Organization of Pillar Arrays into Moiré Patterns Journal Article
In: Physical Review Letters, vol. 107, pp. 177802, 2011, (Selected as Physical Review Letters Editors’ Suggestion and Highlighted in Physics Today and Physics Synopsis. ).
Abstract | Links | BibTeX | Tags: Evaporation, Moire, Nanopillar, Self-Organization
@article{Kang2011,
title = {Meniscus Lithography: Evaporation-Induced Self-Organization of Pillar Arrays into Moiré Patterns},
author = {Sung Hoon Kang and Ning Wu and Alison Grinthal and Joanna Aizenberg},
url = {http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.107.177802},
year = {2011},
date = {2011-10-20},
journal = {Physical Review Letters},
volume = {107},
pages = {177802},
abstract = {We demonstrate a self-organizing system that generates patterns by dynamic feedback: two periodic surfaces collectively structure an intervening liquid sandwiched between them, which then reconfigures the original surface features into moiré patterns as it evaporates. Like the conventional moiré phenomenon, the patterns are deterministic and tunable by mismatch angle, yet additional behaviors—chirality from achiral starting motifs and preservation of the patterns after the surfaces are separated—emerge uniquely from the feedback process. Patterning menisci based on this principle provides a simple, scalable approach for making a series of complex, long-range-ordered structures.},
note = {Selected as Physical Review Letters Editors’ Suggestion and Highlighted in Physics Today and Physics Synopsis. },
keywords = {Evaporation, Moire, Nanopillar, Self-Organization},
pubstate = {published},
tppubtype = {article}
}
We demonstrate a self-organizing system that generates patterns by dynamic feedback: two periodic surfaces collectively structure an intervening liquid sandwiched between them, which then reconfigures the original surface features into moiré patterns as it evaporates. Like the conventional moiré phenomenon, the patterns are deterministic and tunable by mismatch angle, yet additional behaviors—chirality from achiral starting motifs and preservation of the patterns after the surfaces are separated—emerge uniquely from the feedback process. Patterning menisci based on this principle provides a simple, scalable approach for making a series of complex, long-range-ordered structures.
Seminara, Agnese; Pokroy, Boaz; Kang, Sung Hoon; Brenner, Michael P.; Aizenberg, Joanna
On the Mechanism of Nanostructure Movement under Electron Beam and Its Application in Patterning Journal Article
In: Physical Review B, vol. 83, pp. 235438, 2011.
Abstract | Links | BibTeX | Tags: Actuation, Electron Beam, Electrostatic, Nanopillar, Patterning
@article{Seminara2011,
title = {On the Mechanism of Nanostructure Movement under Electron Beam and Its Application in Patterning},
author = {Agnese Seminara and Boaz Pokroy and Sung Hoon Kang and Michael P. Brenner and Joanna Aizenberg},
url = {http://journals.aps.org/prb/abstract/10.1103/PhysRevB.83.235438},
year = {2011},
date = {2011-06-30},
journal = {Physical Review B},
volume = {83},
pages = {235438},
abstract = {In electron microscopy, the motion of the sample features due to the interaction with the electron beam has been traditionally regarded as a detrimental effect. Uncontrolled feature displacement produces artifacts both in imaging and patterning, limiting the resolution and distorting precise nanoscale patterns. The mechanism of such motion remains largely unclear. We present an experimental study of e-beam-induced nanopost movement and offer a mechanistic theoretical model that quantitatively explains the physical phenomenon. We propose that e-beam bombardment produces an uneven distribution of electrons in the sample, and the resulting electrostatic interactions provide forces and torques sufficient to bend the nanoposts. We compare the theoretical predictions with a series of controlled experiments that support our model. We take advantage of this theoretical understanding to demonstrate how this generally undesirable effect can be turned into an unconventional e-beam writing technique to generate pseudo-three-dimensional structures.},
keywords = {Actuation, Electron Beam, Electrostatic, Nanopillar, Patterning},
pubstate = {published},
tppubtype = {article}
}
In electron microscopy, the motion of the sample features due to the interaction with the electron beam has been traditionally regarded as a detrimental effect. Uncontrolled feature displacement produces artifacts both in imaging and patterning, limiting the resolution and distorting precise nanoscale patterns. The mechanism of such motion remains largely unclear. We present an experimental study of e-beam-induced nanopost movement and offer a mechanistic theoretical model that quantitatively explains the physical phenomenon. We propose that e-beam bombardment produces an uneven distribution of electrons in the sample, and the resulting electrostatic interactions provide forces and torques sufficient to bend the nanoposts. We compare the theoretical predictions with a series of controlled experiments that support our model. We take advantage of this theoretical understanding to demonstrate how this generally undesirable effect can be turned into an unconventional e-beam writing technique to generate pseudo-three-dimensional structures.
2010
Kang, Sung Hoon; Pokroy, Boaz; Mahadevan, L.; Aizenberg, Joanna
Control of Shape and Size of Nanopillar Assembly by Adhesion-Mediated Elastocapillary Interaction Journal Article
In: ACS Nano, vol. 4, pp. 6323–6331, 2010, (Featured on the cover and highlighted in the issue.).
Abstract | Links | BibTeX | Tags: Adhesion, bio-inspired science and engineering, Elastocapillary, Evaporation, Nanopillar, Patterning, Self-Organization
@article{Kang2010,
title = {Control of Shape and Size of Nanopillar Assembly by Adhesion-Mediated Elastocapillary Interaction},
author = {Sung Hoon Kang and Boaz Pokroy and L. Mahadevan and Joanna Aizenberg},
url = {http://pubs.acs.org/doi/abs/10.1021/nn102260t},
year = {2010},
date = {2010-11-01},
journal = {ACS Nano},
volume = {4},
pages = {6323–6331},
abstract = {Control of self-organization of nanofibers into regular clusters upon evaporation-induced assembly is receiving increasing attention due to the potential importance of this process in a range of applications including particle trapping, adhesives, and structural color. Here we present a comprehensive study of this phenomenon using a periodic array of polymeric nanopillars with tunable parameters as a model system to study how geometry, mechanical properties, as well as surface properties influence capillary-induced self-organization. In particular, we show that varying the parameters of the building blocks of self-assembly provides us with a simple means of controlling the size, chirality, and anisotropy of complex structures. We observe that chiral assemblies can be generated within a narrow window for each parameter even in the absence of chiral building blocks or a chiral environment. Furthermore, introducing anisotropy in the building blocks provides a way to control both the chirality and the size of the assembly. While capillary-induced self-assembly has been studied and modeled as a quasi-static process involving the competition between only capillary and elastic forces, our results unequivocally show that both adhesion and kinetics are equally important in determining the final assembly. Our findings provide insight into how multiple parameters work together in capillary-induced self-assembly and provide us with a diverse set of options for fabricating a variety of nanostructures by self-assembly.},
note = {Featured on the cover and highlighted in the issue.},
keywords = {Adhesion, bio-inspired science and engineering, Elastocapillary, Evaporation, Nanopillar, Patterning, Self-Organization},
pubstate = {published},
tppubtype = {article}
}
Control of self-organization of nanofibers into regular clusters upon evaporation-induced assembly is receiving increasing attention due to the potential importance of this process in a range of applications including particle trapping, adhesives, and structural color. Here we present a comprehensive study of this phenomenon using a periodic array of polymeric nanopillars with tunable parameters as a model system to study how geometry, mechanical properties, as well as surface properties influence capillary-induced self-organization. In particular, we show that varying the parameters of the building blocks of self-assembly provides us with a simple means of controlling the size, chirality, and anisotropy of complex structures. We observe that chiral assemblies can be generated within a narrow window for each parameter even in the absence of chiral building blocks or a chiral environment. Furthermore, introducing anisotropy in the building blocks provides a way to control both the chirality and the size of the assembly. While capillary-induced self-assembly has been studied and modeled as a quasi-static process involving the competition between only capillary and elastic forces, our results unequivocally show that both adhesion and kinetics are equally important in determining the final assembly. Our findings provide insight into how multiple parameters work together in capillary-induced self-assembly and provide us with a diverse set of options for fabricating a variety of nanostructures by self-assembly.
2009
Pokroy, Boaz; Kang, Sung Hoon; Mahadevan, L.; Aizenberg, Joanna
Self-Organization of a Mesoscale Bristle into Ordered, Hierarchical Helical Assemblies Journal Article
In: Science, vol. 323, pp. 237-240, 2009, (Highlighted in the issue, and various media including New York Times, NPR, Discovery, AAAS EurekAlert, C&EN, Technology Review, IEEE Spectrum, Science Daily, and New Scientist. ).
Abstract | Links | BibTeX | Tags: bio-inspired science and engineering, Helical, Hierarchical, Mesoscale, Nanopillar, Order, Self-Organization
@article{Pokroy2009,
title = {Self-Organization of a Mesoscale Bristle into Ordered, Hierarchical Helical Assemblies},
author = {Boaz Pokroy and Sung Hoon Kang and L. Mahadevan and Joanna Aizenberg
},
url = {http://www.sciencemag.org/content/323/5911/237.short},
year = {2009},
date = {2009-01-09},
journal = {Science},
volume = {323},
pages = {237-240},
abstract = {Mesoscale hierarchical helical structures with diverse functions are abundant in nature. Here we show how spontaneous helicity can be induced in a synthetic polymeric nanobristle assembling in an evaporating liquid. We use a simple theoretical model to characterize the geometry, stiffness, and surface properties of the pillars that favor the adhesive self-organization of bundles with pillars wound around each other. The process can be controlled to yield highly ordered helical clusters with a unique structural hierarchy that arises from the sequential assembly of self-similar coiled building blocks over multiple length scales. We demonstrate their function in the context of self-assembly into previously unseen structures with uniform, periodic patterns and controlled handedness and as an efficient particle-trapping and adhesive system. },
note = {Highlighted in the issue, and various media including New York Times, NPR, Discovery, AAAS EurekAlert, C&EN, Technology Review, IEEE Spectrum, Science Daily, and New Scientist. },
keywords = {bio-inspired science and engineering, Helical, Hierarchical, Mesoscale, Nanopillar, Order, Self-Organization},
pubstate = {published},
tppubtype = {article}
}
Mesoscale hierarchical helical structures with diverse functions are abundant in nature. Here we show how spontaneous helicity can be induced in a synthetic polymeric nanobristle assembling in an evaporating liquid. We use a simple theoretical model to characterize the geometry, stiffness, and surface properties of the pillars that favor the adhesive self-organization of bundles with pillars wound around each other. The process can be controlled to yield highly ordered helical clusters with a unique structural hierarchy that arises from the sequential assembly of self-similar coiled building blocks over multiple length scales. We demonstrate their function in the context of self-assembly into previously unseen structures with uniform, periodic patterns and controlled handedness and as an efficient particle-trapping and adhesive system.