Publications
1.
Orrego, Santiago; Chen, Zhezhi; Krekora, Urszula; Hou, Decheng; Jeon, Seung‐Yeol; Pittman, Matthew; Montoya, Carolina; Chen, Yun; Kang, Sung Hoon
Bioinspired Materials with Self‐Adaptable Mechanical Properties Journal Article
In: Advanced Materials, 2020.
@article{Orrego2020,
title = {Bioinspired Materials with Self‐Adaptable Mechanical Properties},
author = {Santiago Orrego and Zhezhi Chen and Urszula Krekora and Decheng Hou and Seung‐Yeol Jeon and Matthew Pittman and Carolina Montoya and Yun Chen and Sung Hoon Kang},
url = {https://onlinelibrary.wiley.com/doi/full/10.1002/adma.201906970},
doi = {https://doi.org/10.1002/adma.201906970},
year = {2020},
date = {2020-04-17},
journal = {Advanced Materials},
abstract = {Natural structural materials, such as bone, can autonomously modulate their mechanical properties in response to external loading to prevent failure. These material systems smartly control the addition/removal of material in locations of high/low mechanical stress by utilizing local resources guided by biological signals. On the contrary, synthetic structural materials have unchanging mechanical properties limiting their mechanical performance and service life. Inspired by the mineralization process of bone, a material system that adapts its mechanical properties in response to external mechanical loading is reported. It is found that charges from piezoelectric scaffolds can induce mineralization from surrounding media. It is shown that the material system can adapt to external mechanical loading by inducing mineral deposition in proportion to the magnitude of the stress and the resulting piezoelectric charges. Moreover, the mineralization mechanism allows a simple one‐step route for fabricating functionally graded materials by controlling the stress distribution along the scaffold. The findings can pave the way for a new class of self‐regenerating materials that reinforce regions of high stress or induce deposition of minerals on the damaged areas from the increase in mechanical stress to prevent/mitigate failure. It is envisioned that the findings can contribute to addressing the current challenges of synthetic materials for load‐bearing applications from self‐adaptive capabilities.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Natural structural materials, such as bone, can autonomously modulate their mechanical properties in response to external loading to prevent failure. These material systems smartly control the addition/removal of material in locations of high/low mechanical stress by utilizing local resources guided by biological signals. On the contrary, synthetic structural materials have unchanging mechanical properties limiting their mechanical performance and service life. Inspired by the mineralization process of bone, a material system that adapts its mechanical properties in response to external mechanical loading is reported. It is found that charges from piezoelectric scaffolds can induce mineralization from surrounding media. It is shown that the material system can adapt to external mechanical loading by inducing mineral deposition in proportion to the magnitude of the stress and the resulting piezoelectric charges. Moreover, the mineralization mechanism allows a simple one‐step route for fabricating functionally graded materials by controlling the stress distribution along the scaffold. The findings can pave the way for a new class of self‐regenerating materials that reinforce regions of high stress or induce deposition of minerals on the damaged areas from the increase in mechanical stress to prevent/mitigate failure. It is envisioned that the findings can contribute to addressing the current challenges of synthetic materials for load‐bearing applications from self‐adaptive capabilities.
2.
Chen, Shuyang; Li, Jing; Fang, Lichen; Zhu, Zeyu; Kang, Sung Hoon
Simple Triple-State Polymer Actuators with Controllable Folding Characteristics Journal Article
In: Applied Physics Letters, vol. 110, pp. 133506, 2017.
@article{Chen2017,
title = {Simple Triple-State Polymer Actuators with Controllable Folding Characteristics},
author = {Shuyang Chen and Jing Li and Lichen Fang and Zeyu Zhu and Sung Hoon Kang},
url = {http://aip.scitation.org/doi/pdf/10.1063/1.4979560},
doi = {10.1063/1.4979560},
year = {2017},
date = {2017-03-30},
journal = {Applied Physics Letters},
volume = {110},
pages = {133506},
abstract = {Driven by the interests in self-folding, there have been studies developing artificial self-folding structures at different length scales based on various polymer actuators that can realize dual-state actuation. However, their unidirectional nature limits the applicability of the actuators for a wide range of multi-state self-folding behaviors. In addition, complex fabrication and programming procedures hinder broad applications of existing polymer actuators. Moreover, few of the exiting polymer actuators are able to show the self-folding behaviors with precise control of curvature and force. To address these issues, we report an easy-to-fabricate triple-state actuator with controllable folding behaviors based on bilayer polymer composites with different glass transition temperatures. Initially, the fabricated actuator is in flat state, and it can sequentially self-fold to angled folding states of opposite directions as it is heated up. Based on an analytical model and measured partial recovery behaviors of polymers, we can accurately control the folding characteristics (curvature and force) for rational design. To demonstrate an application of our triple-state actuator, we have developed a self-folding transformer robot which self-folds from a two-dimensional sheet into a three-dimensional boat-like configuration and transforms from the boat shape to a car shape with the increase of the temperature applied to the actuator. Our findings offer a simple approach to generate multiple configurations from a single system by harnessing behaviors of polymers with rational design.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Driven by the interests in self-folding, there have been studies developing artificial self-folding structures at different length scales based on various polymer actuators that can realize dual-state actuation. However, their unidirectional nature limits the applicability of the actuators for a wide range of multi-state self-folding behaviors. In addition, complex fabrication and programming procedures hinder broad applications of existing polymer actuators. Moreover, few of the exiting polymer actuators are able to show the self-folding behaviors with precise control of curvature and force. To address these issues, we report an easy-to-fabricate triple-state actuator with controllable folding behaviors based on bilayer polymer composites with different glass transition temperatures. Initially, the fabricated actuator is in flat state, and it can sequentially self-fold to angled folding states of opposite directions as it is heated up. Based on an analytical model and measured partial recovery behaviors of polymers, we can accurately control the folding characteristics (curvature and force) for rational design. To demonstrate an application of our triple-state actuator, we have developed a self-folding transformer robot which self-folds from a two-dimensional sheet into a three-dimensional boat-like configuration and transforms from the boat shape to a car shape with the increase of the temperature applied to the actuator. Our findings offer a simple approach to generate multiple configurations from a single system by harnessing behaviors of polymers with rational design.
3.
Grinthal, Alison; Kang, Sung Hoon; Epstein, Alexander K.; Aizenberg, Michael; Khan, Mughees; Aizenberg, Joanna
Steering Nanofibers: An Integrative Approach to Bio-Inspired Fiber Fabrication and Assembly Journal Article
In: Nano Today, vol. 7, pp. 35-52, 2012, (Invited Review).
@article{Grinthal2012,
title = {Steering Nanofibers: An Integrative Approach to Bio-Inspired Fiber Fabrication and Assembly},
author = {Alison Grinthal and Sung Hoon Kang and Alexander K. Epstein and Michael Aizenberg and Mughees Khan and Joanna Aizenberg},
url = {http://www.sciencedirect.com/science/article/pii/S1748013211001411},
year = {2012},
date = {2012-02-01},
journal = {Nano Today},
volume = {7},
pages = {35-52},
abstract = {As seen throughout the natural world, nanoscale fibers exhibit a unique combination of mechanical and surface properties that enable them to wind and bend around each other into an immense diversity of complex forms. In this review, we discuss how this versatility can be harnessed to transform a simple array of anchored nanofibers into a variety of complex, hierarchically organized dynamic functional surfaces. We describe a set of recently developed benchtop techniques that provide a straightforward way to generate libraries of fibrous surfaces with a wide range of finely tuned, nearly arbitrary geometric, mechanical, material, and surface characteristics starting from a single master array. These simple systematic controls can be used to program the fibers to bundle together, twist around each other into chiral swirls, and assemble into patterned arrays of complex hierarchical architectures. The delicate balance between fiber elasticity and surface adhesion plays a critical role in determining the shape, chirality, and higher order of the assembled structures, as does the dynamic evolution of the geometric, mechanical, and surface parameters throughout the assembly process. Hierarchical assembly can also be programmed to run backwards, enabling a wide range of reversible, responsive behaviors to be encoded through rationally chosen surface chemistry. These strategies provide a foundation for designing a vast assortment of functional surfaces with anti-fouling, adhesive, optical, water and ice repellent, memory storage, microfluidic, capture and release, and many more capabilities with the structural and dynamic sophistication of their biological counterparts.},
note = {Invited Review},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
As seen throughout the natural world, nanoscale fibers exhibit a unique combination of mechanical and surface properties that enable them to wind and bend around each other into an immense diversity of complex forms. In this review, we discuss how this versatility can be harnessed to transform a simple array of anchored nanofibers into a variety of complex, hierarchically organized dynamic functional surfaces. We describe a set of recently developed benchtop techniques that provide a straightforward way to generate libraries of fibrous surfaces with a wide range of finely tuned, nearly arbitrary geometric, mechanical, material, and surface characteristics starting from a single master array. These simple systematic controls can be used to program the fibers to bundle together, twist around each other into chiral swirls, and assemble into patterned arrays of complex hierarchical architectures. The delicate balance between fiber elasticity and surface adhesion plays a critical role in determining the shape, chirality, and higher order of the assembled structures, as does the dynamic evolution of the geometric, mechanical, and surface parameters throughout the assembly process. Hierarchical assembly can also be programmed to run backwards, enabling a wide range of reversible, responsive behaviors to be encoded through rationally chosen surface chemistry. These strategies provide a foundation for designing a vast assortment of functional surfaces with anti-fouling, adhesive, optical, water and ice repellent, memory storage, microfluidic, capture and release, and many more capabilities with the structural and dynamic sophistication of their biological counterparts.
4.
Wong, Tak-Sing; Kang, Sung Hoon; Tang, Sindy. K. Y.; Smythe, Elizabeth J.; Hatton, Benjamin D.; Grinthal, Alison; Aizenberg, Joanna
Bioinspired Self-Repairing Slippery Surfaces with Pressure-Stable Omniphobicity Journal Article
In: Nature, vol. 477, pp. 443–447, 2011, (Image Credits: James C. Weaver and Peter Allen. Selected for 2012 R&D 100 Award. Featured on News & Views, highlighted in the issue of Nature and various media worldwide including BBC, the Times, Daily Mail, ABC (Australia & Spain), Discovery, Financial Times, Yahoo News (UK), Agence France-Presse, Sina (China), the Statesman (India), Nature Chemistry, Hot Topic Article in Nature Asia-Pacific, C&EN, AAAS EurekAlert, Chemistry World, Physics World, Spektrum Der Wissenschaft, New Scientist, and the Engineer).
@article{Wong2011,
title = {Bioinspired Self-Repairing Slippery Surfaces with Pressure-Stable Omniphobicity},
author = {Tak-Sing Wong and Sung Hoon Kang and Sindy. K. Y. Tang and Elizabeth J. Smythe and Benjamin D. Hatton and Alison Grinthal and Joanna Aizenberg},
url = {http://www.nature.com/nature/journal/v477/n7365/full/nature10447.html},
year = {2011},
date = {2011-09-22},
journal = {Nature},
volume = {477},
pages = {443–447},
abstract = {Creating a robust synthetic surface that repels various liquids would have broad technological implications for areas ranging from biomedical devices and fuel transport to architecture but has proved extremely challenging1. Inspirations from natural nonwetting structures2, 3, 4, 5, 6, particularly the leaves of the lotus, have led to the development of liquid-repellent microtextured surfaces that rely on the formation of a stable air–liquid interface7, 8, 9. Despite over a decade of intense research, these surfaces are, however, still plagued with problems that restrict their practical applications: limited oleophobicity with high contact angle hysteresis9, failure under pressure10, 11, 12 and upon physical damage1, 7, 11, inability to self-heal and high production cost1, 11. To address these challenges, here we report a strategy to create self-healing, slippery liquid-infused porous surface(s) (SLIPS) with exceptional liquid- and ice-repellency, pressure stability and enhanced optical transparency. Our approach—inspired by Nepenthes pitcher plants13—is conceptually different from the lotus effect, because we use nano/microstructured substrates to lock in place the infused lubricating fluid. We define the requirements for which the lubricant forms a stable, defect-free and inert ‘slippery’ interface. This surface outperforms its natural counterparts2, 3, 4, 5, 6 and state-of-the-art synthetic liquid-repellent surfaces8, 9, 14, 15, 16 in its capability to repel various simple and complex liquids (water, hydrocarbons, crude oil and blood), maintain low contact angle hysteresis (<2.5°), quickly restore liquid-repellency after physical damage (within 0.1–1 s), resist ice adhesion, and function at high pressures (up to about 680 atm). We show that these properties are insensitive to the precise geometry of the underlying substrate, making our approach applicable to various inexpensive, low-surface-energy structured materials (such as porous Teflon membrane). We envision that these slippery surfaces will be useful in fluid handling and transportation, optical sensing, medicine, and as self-cleaning and anti-fouling materials operating in extreme environments.},
note = {Image Credits: James C. Weaver and Peter Allen.
Selected for 2012 R&D 100 Award.
Featured on News & Views, highlighted in the issue of Nature and various media worldwide including BBC, the Times, Daily Mail, ABC (Australia & Spain), Discovery, Financial Times, Yahoo News (UK), Agence France-Presse, Sina (China), the Statesman (India), Nature Chemistry, Hot Topic Article in Nature Asia-Pacific, C&EN, AAAS EurekAlert, Chemistry World, Physics World, Spektrum Der Wissenschaft, New Scientist, and the Engineer},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Creating a robust synthetic surface that repels various liquids would have broad technological implications for areas ranging from biomedical devices and fuel transport to architecture but has proved extremely challenging1. Inspirations from natural nonwetting structures2, 3, 4, 5, 6, particularly the leaves of the lotus, have led to the development of liquid-repellent microtextured surfaces that rely on the formation of a stable air–liquid interface7, 8, 9. Despite over a decade of intense research, these surfaces are, however, still plagued with problems that restrict their practical applications: limited oleophobicity with high contact angle hysteresis9, failure under pressure10, 11, 12 and upon physical damage1, 7, 11, inability to self-heal and high production cost1, 11. To address these challenges, here we report a strategy to create self-healing, slippery liquid-infused porous surface(s) (SLIPS) with exceptional liquid- and ice-repellency, pressure stability and enhanced optical transparency. Our approach—inspired by Nepenthes pitcher plants13—is conceptually different from the lotus effect, because we use nano/microstructured substrates to lock in place the infused lubricating fluid. We define the requirements for which the lubricant forms a stable, defect-free and inert ‘slippery’ interface. This surface outperforms its natural counterparts2, 3, 4, 5, 6 and state-of-the-art synthetic liquid-repellent surfaces8, 9, 14, 15, 16 in its capability to repel various simple and complex liquids (water, hydrocarbons, crude oil and blood), maintain low contact angle hysteresis (<2.5°), quickly restore liquid-repellency after physical damage (within 0.1–1 s), resist ice adhesion, and function at high pressures (up to about 680 atm). We show that these properties are insensitive to the precise geometry of the underlying substrate, making our approach applicable to various inexpensive, low-surface-energy structured materials (such as porous Teflon membrane). We envision that these slippery surfaces will be useful in fluid handling and transportation, optical sensing, medicine, and as self-cleaning and anti-fouling materials operating in extreme environments.
Note: Send e-mail to Prof. Kang at [email protected] if you need a pdf file of the papers below.
2020
Orrego, Santiago; Chen, Zhezhi; Krekora, Urszula; Hou, Decheng; Jeon, Seung‐Yeol; Pittman, Matthew; Montoya, Carolina; Chen, Yun; Kang, Sung Hoon
Bioinspired Materials with Self‐Adaptable Mechanical Properties Journal Article
In: Advanced Materials, 2020.
Abstract | Links | BibTeX | Tags: adaptive, Bio-Inspired, bio-inspired science and engineering, biomaterial, mechanics of soft materials and structures, mineral, multifunctional material, piezoelectric, porous structure, regeneration
@article{Orrego2020,
title = {Bioinspired Materials with Self‐Adaptable Mechanical Properties},
author = {Santiago Orrego and Zhezhi Chen and Urszula Krekora and Decheng Hou and Seung‐Yeol Jeon and Matthew Pittman and Carolina Montoya and Yun Chen and Sung Hoon Kang},
url = {https://onlinelibrary.wiley.com/doi/full/10.1002/adma.201906970},
doi = {https://doi.org/10.1002/adma.201906970},
year = {2020},
date = {2020-04-17},
journal = {Advanced Materials},
abstract = {Natural structural materials, such as bone, can autonomously modulate their mechanical properties in response to external loading to prevent failure. These material systems smartly control the addition/removal of material in locations of high/low mechanical stress by utilizing local resources guided by biological signals. On the contrary, synthetic structural materials have unchanging mechanical properties limiting their mechanical performance and service life. Inspired by the mineralization process of bone, a material system that adapts its mechanical properties in response to external mechanical loading is reported. It is found that charges from piezoelectric scaffolds can induce mineralization from surrounding media. It is shown that the material system can adapt to external mechanical loading by inducing mineral deposition in proportion to the magnitude of the stress and the resulting piezoelectric charges. Moreover, the mineralization mechanism allows a simple one‐step route for fabricating functionally graded materials by controlling the stress distribution along the scaffold. The findings can pave the way for a new class of self‐regenerating materials that reinforce regions of high stress or induce deposition of minerals on the damaged areas from the increase in mechanical stress to prevent/mitigate failure. It is envisioned that the findings can contribute to addressing the current challenges of synthetic materials for load‐bearing applications from self‐adaptive capabilities.},
keywords = {adaptive, Bio-Inspired, bio-inspired science and engineering, biomaterial, mechanics of soft materials and structures, mineral, multifunctional material, piezoelectric, porous structure, regeneration},
pubstate = {published},
tppubtype = {article}
}
Natural structural materials, such as bone, can autonomously modulate their mechanical properties in response to external loading to prevent failure. These material systems smartly control the addition/removal of material in locations of high/low mechanical stress by utilizing local resources guided by biological signals. On the contrary, synthetic structural materials have unchanging mechanical properties limiting their mechanical performance and service life. Inspired by the mineralization process of bone, a material system that adapts its mechanical properties in response to external mechanical loading is reported. It is found that charges from piezoelectric scaffolds can induce mineralization from surrounding media. It is shown that the material system can adapt to external mechanical loading by inducing mineral deposition in proportion to the magnitude of the stress and the resulting piezoelectric charges. Moreover, the mineralization mechanism allows a simple one‐step route for fabricating functionally graded materials by controlling the stress distribution along the scaffold. The findings can pave the way for a new class of self‐regenerating materials that reinforce regions of high stress or induce deposition of minerals on the damaged areas from the increase in mechanical stress to prevent/mitigate failure. It is envisioned that the findings can contribute to addressing the current challenges of synthetic materials for load‐bearing applications from self‐adaptive capabilities.
2017
Chen, Shuyang; Li, Jing; Fang, Lichen; Zhu, Zeyu; Kang, Sung Hoon
Simple Triple-State Polymer Actuators with Controllable Folding Characteristics Journal Article
In: Applied Physics Letters, vol. 110, pp. 133506, 2017.
Abstract | Links | BibTeX | Tags: Bio-Inspired, mechanics of soft materials and structures, polymer, programmable material, Self-Folding, transformer
@article{Chen2017,
title = {Simple Triple-State Polymer Actuators with Controllable Folding Characteristics},
author = {Shuyang Chen and Jing Li and Lichen Fang and Zeyu Zhu and Sung Hoon Kang},
url = {http://aip.scitation.org/doi/pdf/10.1063/1.4979560},
doi = {10.1063/1.4979560},
year = {2017},
date = {2017-03-30},
journal = {Applied Physics Letters},
volume = {110},
pages = {133506},
abstract = {Driven by the interests in self-folding, there have been studies developing artificial self-folding structures at different length scales based on various polymer actuators that can realize dual-state actuation. However, their unidirectional nature limits the applicability of the actuators for a wide range of multi-state self-folding behaviors. In addition, complex fabrication and programming procedures hinder broad applications of existing polymer actuators. Moreover, few of the exiting polymer actuators are able to show the self-folding behaviors with precise control of curvature and force. To address these issues, we report an easy-to-fabricate triple-state actuator with controllable folding behaviors based on bilayer polymer composites with different glass transition temperatures. Initially, the fabricated actuator is in flat state, and it can sequentially self-fold to angled folding states of opposite directions as it is heated up. Based on an analytical model and measured partial recovery behaviors of polymers, we can accurately control the folding characteristics (curvature and force) for rational design. To demonstrate an application of our triple-state actuator, we have developed a self-folding transformer robot which self-folds from a two-dimensional sheet into a three-dimensional boat-like configuration and transforms from the boat shape to a car shape with the increase of the temperature applied to the actuator. Our findings offer a simple approach to generate multiple configurations from a single system by harnessing behaviors of polymers with rational design.},
keywords = {Bio-Inspired, mechanics of soft materials and structures, polymer, programmable material, Self-Folding, transformer},
pubstate = {published},
tppubtype = {article}
}
Driven by the interests in self-folding, there have been studies developing artificial self-folding structures at different length scales based on various polymer actuators that can realize dual-state actuation. However, their unidirectional nature limits the applicability of the actuators for a wide range of multi-state self-folding behaviors. In addition, complex fabrication and programming procedures hinder broad applications of existing polymer actuators. Moreover, few of the exiting polymer actuators are able to show the self-folding behaviors with precise control of curvature and force. To address these issues, we report an easy-to-fabricate triple-state actuator with controllable folding behaviors based on bilayer polymer composites with different glass transition temperatures. Initially, the fabricated actuator is in flat state, and it can sequentially self-fold to angled folding states of opposite directions as it is heated up. Based on an analytical model and measured partial recovery behaviors of polymers, we can accurately control the folding characteristics (curvature and force) for rational design. To demonstrate an application of our triple-state actuator, we have developed a self-folding transformer robot which self-folds from a two-dimensional sheet into a three-dimensional boat-like configuration and transforms from the boat shape to a car shape with the increase of the temperature applied to the actuator. Our findings offer a simple approach to generate multiple configurations from a single system by harnessing behaviors of polymers with rational design.
2012
Grinthal, Alison; Kang, Sung Hoon; Epstein, Alexander K.; Aizenberg, Michael; Khan, Mughees; Aizenberg, Joanna
Steering Nanofibers: An Integrative Approach to Bio-Inspired Fiber Fabrication and Assembly Journal Article
In: Nano Today, vol. 7, pp. 35-52, 2012, (Invited Review).
Abstract | Links | BibTeX | Tags: Assembly, Bio-Inspired, bio-inspired science and engineering, Chemistry, Fabrication, Geometry, Hierarchical, Mechanics, Nanofiber, Symmetry
@article{Grinthal2012,
title = {Steering Nanofibers: An Integrative Approach to Bio-Inspired Fiber Fabrication and Assembly},
author = {Alison Grinthal and Sung Hoon Kang and Alexander K. Epstein and Michael Aizenberg and Mughees Khan and Joanna Aizenberg},
url = {http://www.sciencedirect.com/science/article/pii/S1748013211001411},
year = {2012},
date = {2012-02-01},
journal = {Nano Today},
volume = {7},
pages = {35-52},
abstract = {As seen throughout the natural world, nanoscale fibers exhibit a unique combination of mechanical and surface properties that enable them to wind and bend around each other into an immense diversity of complex forms. In this review, we discuss how this versatility can be harnessed to transform a simple array of anchored nanofibers into a variety of complex, hierarchically organized dynamic functional surfaces. We describe a set of recently developed benchtop techniques that provide a straightforward way to generate libraries of fibrous surfaces with a wide range of finely tuned, nearly arbitrary geometric, mechanical, material, and surface characteristics starting from a single master array. These simple systematic controls can be used to program the fibers to bundle together, twist around each other into chiral swirls, and assemble into patterned arrays of complex hierarchical architectures. The delicate balance between fiber elasticity and surface adhesion plays a critical role in determining the shape, chirality, and higher order of the assembled structures, as does the dynamic evolution of the geometric, mechanical, and surface parameters throughout the assembly process. Hierarchical assembly can also be programmed to run backwards, enabling a wide range of reversible, responsive behaviors to be encoded through rationally chosen surface chemistry. These strategies provide a foundation for designing a vast assortment of functional surfaces with anti-fouling, adhesive, optical, water and ice repellent, memory storage, microfluidic, capture and release, and many more capabilities with the structural and dynamic sophistication of their biological counterparts.},
note = {Invited Review},
keywords = {Assembly, Bio-Inspired, bio-inspired science and engineering, Chemistry, Fabrication, Geometry, Hierarchical, Mechanics, Nanofiber, Symmetry},
pubstate = {published},
tppubtype = {article}
}
As seen throughout the natural world, nanoscale fibers exhibit a unique combination of mechanical and surface properties that enable them to wind and bend around each other into an immense diversity of complex forms. In this review, we discuss how this versatility can be harnessed to transform a simple array of anchored nanofibers into a variety of complex, hierarchically organized dynamic functional surfaces. We describe a set of recently developed benchtop techniques that provide a straightforward way to generate libraries of fibrous surfaces with a wide range of finely tuned, nearly arbitrary geometric, mechanical, material, and surface characteristics starting from a single master array. These simple systematic controls can be used to program the fibers to bundle together, twist around each other into chiral swirls, and assemble into patterned arrays of complex hierarchical architectures. The delicate balance between fiber elasticity and surface adhesion plays a critical role in determining the shape, chirality, and higher order of the assembled structures, as does the dynamic evolution of the geometric, mechanical, and surface parameters throughout the assembly process. Hierarchical assembly can also be programmed to run backwards, enabling a wide range of reversible, responsive behaviors to be encoded through rationally chosen surface chemistry. These strategies provide a foundation for designing a vast assortment of functional surfaces with anti-fouling, adhesive, optical, water and ice repellent, memory storage, microfluidic, capture and release, and many more capabilities with the structural and dynamic sophistication of their biological counterparts.
2011
Wong, Tak-Sing; Kang, Sung Hoon; Tang, Sindy. K. Y.; Smythe, Elizabeth J.; Hatton, Benjamin D.; Grinthal, Alison; Aizenberg, Joanna
Bioinspired Self-Repairing Slippery Surfaces with Pressure-Stable Omniphobicity Journal Article
In: Nature, vol. 477, pp. 443–447, 2011, (Image Credits: James C. Weaver and Peter Allen. Selected for 2012 R&D 100 Award. Featured on News & Views, highlighted in the issue of Nature and various media worldwide including BBC, the Times, Daily Mail, ABC (Australia & Spain), Discovery, Financial Times, Yahoo News (UK), Agence France-Presse, Sina (China), the Statesman (India), Nature Chemistry, Hot Topic Article in Nature Asia-Pacific, C&EN, AAAS EurekAlert, Chemistry World, Physics World, Spektrum Der Wissenschaft, New Scientist, and the Engineer).
Abstract | Links | BibTeX | Tags: Bio-Inspired, Omniphobic, Pressure-Stable, Self-Repair, Slippery, Surface
@article{Wong2011,
title = {Bioinspired Self-Repairing Slippery Surfaces with Pressure-Stable Omniphobicity},
author = {Tak-Sing Wong and Sung Hoon Kang and Sindy. K. Y. Tang and Elizabeth J. Smythe and Benjamin D. Hatton and Alison Grinthal and Joanna Aizenberg},
url = {http://www.nature.com/nature/journal/v477/n7365/full/nature10447.html},
year = {2011},
date = {2011-09-22},
journal = {Nature},
volume = {477},
pages = {443–447},
abstract = {Creating a robust synthetic surface that repels various liquids would have broad technological implications for areas ranging from biomedical devices and fuel transport to architecture but has proved extremely challenging1. Inspirations from natural nonwetting structures2, 3, 4, 5, 6, particularly the leaves of the lotus, have led to the development of liquid-repellent microtextured surfaces that rely on the formation of a stable air–liquid interface7, 8, 9. Despite over a decade of intense research, these surfaces are, however, still plagued with problems that restrict their practical applications: limited oleophobicity with high contact angle hysteresis9, failure under pressure10, 11, 12 and upon physical damage1, 7, 11, inability to self-heal and high production cost1, 11. To address these challenges, here we report a strategy to create self-healing, slippery liquid-infused porous surface(s) (SLIPS) with exceptional liquid- and ice-repellency, pressure stability and enhanced optical transparency. Our approach—inspired by Nepenthes pitcher plants13—is conceptually different from the lotus effect, because we use nano/microstructured substrates to lock in place the infused lubricating fluid. We define the requirements for which the lubricant forms a stable, defect-free and inert ‘slippery’ interface. This surface outperforms its natural counterparts2, 3, 4, 5, 6 and state-of-the-art synthetic liquid-repellent surfaces8, 9, 14, 15, 16 in its capability to repel various simple and complex liquids (water, hydrocarbons, crude oil and blood), maintain low contact angle hysteresis (<2.5°), quickly restore liquid-repellency after physical damage (within 0.1–1 s), resist ice adhesion, and function at high pressures (up to about 680 atm). We show that these properties are insensitive to the precise geometry of the underlying substrate, making our approach applicable to various inexpensive, low-surface-energy structured materials (such as porous Teflon membrane). We envision that these slippery surfaces will be useful in fluid handling and transportation, optical sensing, medicine, and as self-cleaning and anti-fouling materials operating in extreme environments.},
note = {Image Credits: James C. Weaver and Peter Allen.
Selected for 2012 R&D 100 Award.
Featured on News & Views, highlighted in the issue of Nature and various media worldwide including BBC, the Times, Daily Mail, ABC (Australia & Spain), Discovery, Financial Times, Yahoo News (UK), Agence France-Presse, Sina (China), the Statesman (India), Nature Chemistry, Hot Topic Article in Nature Asia-Pacific, C&EN, AAAS EurekAlert, Chemistry World, Physics World, Spektrum Der Wissenschaft, New Scientist, and the Engineer},
keywords = {Bio-Inspired, Omniphobic, Pressure-Stable, Self-Repair, Slippery, Surface},
pubstate = {published},
tppubtype = {article}
}
Creating a robust synthetic surface that repels various liquids would have broad technological implications for areas ranging from biomedical devices and fuel transport to architecture but has proved extremely challenging1. Inspirations from natural nonwetting structures2, 3, 4, 5, 6, particularly the leaves of the lotus, have led to the development of liquid-repellent microtextured surfaces that rely on the formation of a stable air–liquid interface7, 8, 9. Despite over a decade of intense research, these surfaces are, however, still plagued with problems that restrict their practical applications: limited oleophobicity with high contact angle hysteresis9, failure under pressure10, 11, 12 and upon physical damage1, 7, 11, inability to self-heal and high production cost1, 11. To address these challenges, here we report a strategy to create self-healing, slippery liquid-infused porous surface(s) (SLIPS) with exceptional liquid- and ice-repellency, pressure stability and enhanced optical transparency. Our approach—inspired by Nepenthes pitcher plants13—is conceptually different from the lotus effect, because we use nano/microstructured substrates to lock in place the infused lubricating fluid. We define the requirements for which the lubricant forms a stable, defect-free and inert ‘slippery’ interface. This surface outperforms its natural counterparts2, 3, 4, 5, 6 and state-of-the-art synthetic liquid-repellent surfaces8, 9, 14, 15, 16 in its capability to repel various simple and complex liquids (water, hydrocarbons, crude oil and blood), maintain low contact angle hysteresis (<2.5°), quickly restore liquid-repellency after physical damage (within 0.1–1 s), resist ice adhesion, and function at high pressures (up to about 680 atm). We show that these properties are insensitive to the precise geometry of the underlying substrate, making our approach applicable to various inexpensive, low-surface-energy structured materials (such as porous Teflon membrane). We envision that these slippery surfaces will be useful in fluid handling and transportation, optical sensing, medicine, and as self-cleaning and anti-fouling materials operating in extreme environments.