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News Article | September 27, 2016
Site: www.rdmag.com

With the help of camera-guided endoscopes, clinicians get a look inside the body's cavities to diagnose and treat many different conditions. In the United States alone, up to 20 million endoscopies are performed on patients every year. But even for the most seasoned endoscope users, the instruments can prove very challenging to use effectively; this is due to the fact that blood and other bodily fluids quite commonly obscure the camera lens in the midst of critical procedures. This problem inspired a team led by Joanna Aizenberg, Amy Smith Berylson Professor of Materials Science and Professor of Chemistry & Chemical Biology at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) and Core Faculty member of the Wyss Institute for Biologically Inspired Engineering at Harvard University, to engineer a transparent surface coating for an endoscope lens that could effortlessly keep blood and other fluids at bay. The idea took roots in conversations Aizenberg had with clinician collaborators, who were quick to lament the propensity for endoscopes to become clouded mid-procedure. Turning to the portfolio of SLIPS (Slippery Liquid-Infused Porous Surfaces) technologies already invented by Aizenberg, they set out to design a specialized SLIPS coating that could prevent bodily fluids from blocking the optical field of view of camera-guided endoscopes. The demonstrated results of their work are published online this week in the Proceedings of the National Academy of Sciences (PNAS) journal. "Endoscopes are used by many physicians around the world for a variety of procedures, and ironically, the moment when bleeding occurs and the optical field is blocked is also precisely when physicians most need to see what's happening," said Aizenberg, who is also the Co-Director of the Kavli Institute for Bionano Science and Technology. Aizenberg's SLIPS technology creates non-wetting and robust self-cleaning surfaces that can resist almost any fouling challenge a surface may face. But to develop the technology for endoscopic use, the team needed to adapt SLIPS specifically to weather the harsh environment of a living body's cavities. "In addition to being entirely transparent and able to coat the curvature of the glass camera lens on the endoscope, the coating also needs to withstand constant contact and abrasion with soft tissues and corrosive bodily fluids," said Steffi Sunny, a co-first author on the study and a graduate student at SEAS and researcher at the Wyss. To achieve this, the team deposited silica nanoparticles layer by layer onto an endoscope's glass camera lens. These silica layers create a porous surface that, at the nanoscale, would be considered "rough" and filled with caverns. They then functionalized this "rough" surface and infused it with a medical-grade silicone oil, filling in the porous cavities and creating a self-replenishing liquid layer. The end result, an entirely biocompatible coating, can endure many procedural uses and standard sterilization protocols, and can be even re-applied with silicone oil intermittently to maintain its extreme repellency. Working with co-first author George Cheng the team tested their antifouling endoscope in vivo, specifically in bronchoscopy. Bronchoscopy is one of the most commonly performed procedures on patients with pathological lung conditions. Cheng, who was an Interventional Pulmonary Fellow at Harvard Combined Training Program (Beth Israel Deaconess Medical Center and Massachusetts General Hospital) at the time of the study, performed bronchoscopy with the modified endoscope on an anesthetized pig to evaluate its effectiveness. "The proof of concept experiment in the pig lung worked beautifully," said Cheng, who today is Assistant Professor of Medicine in the Division of Pulmonary, Allergy and Critical Care at Duke University. "It very easily repelled blood and mucus and dramatically reduced the complexity of the procedure." Conventional scopes generally cause the procedure time to be longer than necessary, due to the need to repeatedly clean and wipe away fluids that obscure the optical field. An antifouling endoscope could, one day, not only improve ease and precision of endoscopies, but could also result in more positive patient outcomes due to a shortened procedural time, significantly reduced side-effects often associated with mid-procedure lens cleaning, less sedation needed, and decreased recovery time. SLIPS-coated endoscopes could even expand our view into new areas of the body that we have not yet been able to access with a camera. Today's endoscopes, which contain irrigation and suction channels to flush away build up from the lens mid-procedure, are limited in how small they can be made due to this important cleansing feature. But the super repellent coating on the lens could potentially eliminate the need for a wash port, leading to more miniaturized endoscopes, which would allow physicians to reach, observe and treat the areas of the body that are off-limits to endoscopes of current sizes. Looking ahead, the team also hopes that their slippery lens coating could have applications in other camera-guided instruments that operate in harsh, contaminated environments and rely on an unobstructed optical field, such as oil exploration, robotics, marine exploration, plumbing and sanitation and drain pipe maintenance.


News Article | January 27, 2016
Site: www.rdmag.com

What if you could make any object out of a flat sheet of paper? That future is on the horizon thanks to new research by L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, Organismic and Evolutionary Biology, and Physics at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). He is also a core faculty member of the Wyss Institute for Biologically Inspired Engineering, and member of the Kavli Institute for Bionano Science and Technology, at Harvard Univ.. Mahadevan and his team have characterized a fundamental origami fold, or tessellation, that could be used as a building block to create almost any three-dimensional shape, from nanostructures to buildings. The research is published in Nature Materials. The folding pattern, known as the Miura-ori, is a periodic way to tile the plane using the simplest mountain-valley fold in origami. It was used as a decorative item in clothing at least as long ago as the 15th century. A folded Miura can be packed into a flat, compact shape and unfolded in one continuous motion, making it ideal for packing rigid structures like solar panels. It also occurs in nature in a variety of situations, such as in insect wings and certain leaves. "Could this simple folding pattern serve as a template for more complicated shapes, such as saddles, spheres, cylinders, and helices?" asked Mahadevan. "We found an incredible amount of flexibility hidden inside the geometry of the Miura-ori," said Levi Dudte, graduate student in the Mahadevan lab and first author of the paper. "As it turns out, this fold is capable of creating many more shapes than we imagined." Think surgical stents that can be packed flat and pop-up into three-dimensional structures once inside the body or dining room tables that can lean flat against the wall until they are ready to be used. "The collapsibility, transportability and deployability of Miura-ori folded objects makes it a potentially attractive design for everything from space-bound payloads to small-space living to laparoscopic surgery and soft robotics," said Dudte. To explore the potential of the tessellation, the team developed an algorithm that can create certain shapes using the Miura-ori fold, repeated with small variations. Given the specifications of the target shape, the program lays out the folds needed to create the design, which can then be laser printed for folding. The program takes into account several factors, including the stiffness of the folded material and the trade-off between the accuracy of the pattern and the effort associated with creating finer folds - an important characterization because, as of now, these shapes are all folded by hand. "Essentially, we would like to be able to tailor any shape by using an appropriate folding pattern," said Mahadevan. "Starting with the basic mountain-valley fold, our algorithm determines how to vary it by gently tweaking it from one location to the other to make a vase, a hat, a saddle, or to stitch them together to make more and more complex structures." "This is a step in the direction of being able to solve the inverse problem - given a functional shape, how can we design the folds on a sheet to achieve it," Dudte said. "The really exciting thing about this fold is it is completely scalable," said Mahadevan. "You can do this with graphene, which is one atom thick, or you can do it on the architectural scale."


What if you could make any object out of a flat sheet of paper? That future is on the horizon thanks to new research by L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, Organismic and Evolutionary Biology, and Physics at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). He is also a core faculty member of the Wyss Institute for Biologically Inspired Engineering, and member of the Kavli Institute for Bionano Science and Technology, at Harvard University. Mahadevan and his team have characterized a fundamental origami fold, or tessellation, that could be used as a building block to create almost any three-dimensional shape, from nanostructures to buildings. The research is published in Nature Materials. The folding pattern, known as the Miura-ori, is a periodic way to tile the plane using the simplest mountain-valley fold in origami. It was used as a decorative item in clothing at least as long ago as the 15th century. A folded Miura can be packed into a flat, compact shape and unfolded in one continuous motion, making it ideal for packing rigid structures like solar panels. It also occurs in nature in a variety of situations, such as in insect wings and certain leaves. "Could this simple folding pattern serve as a template for more complicated shapes, such as saddles, spheres, cylinders, and helices?" asked Mahadevan. "We found an incredible amount of flexibility hidden inside the geometry of the Miura-ori," said Levi Dudte, graduate student in the Mahadevan lab and first author of the paper. "As it turns out, this fold is capable of creating many more shapes than we imagined." Think surgical stents that can be packed flat and pop-up into three-dimensional structures once inside the body or dining room tables that can lean flat against the wall until they are ready to be used. "The collapsibility, transportability and deployability of Miura-ori folded objects makes it a potentially attractive design for everything from space-bound payloads to small-space living to laparoscopic surgery and soft robotics," said Dudte. To explore the potential of the tessellation, the team developed an algorithm that can create certain shapes using the Miura-ori fold, repeated with small variations. Given the specifications of the target shape, the program lays out the folds needed to create the design, which can then be laser printed for folding. The program takes into account several factors, including the stiffness of the folded material and the trade-off between the accuracy of the pattern and the effort associated with creating finer folds - an important characterization because, as of now, these shapes are all folded by hand. "Essentially, we would like to be able to tailor any shape by using an appropriate folding pattern," said Mahadevan. "Starting with the basic mountain-valley fold, our algorithm determines how to vary it by gently tweaking it from one location to the other to make a vase, a hat, a saddle, or to stitch them together to make more and more complex structures." "This is a step in the direction of being able to solve the inverse problem - given a functional shape, how can we design the folds on a sheet to achieve it," Dudte said. "The really exciting thing about this fold is it is completely scalable," said Mahadevan. "You can do this with graphene, which is one atom thick, or you can do it on the architectural scale."


News Article | February 2, 2016
Site: www.biosciencetechnology.com

The distinctive troughs and crests of the human brain are not present in most animals; highly folded brains are seen only in a handful of species, including some primates, dolphins, elephants, and pigs. In humans, folding begins in fetal brains around the 20th week of gestation and is completed only when the child is about 18 months old. Why the brain is folded can be rationalized easily from an evolutionary perspective: Folded brains likely evolved to fit a large cortex into a small volume with the benefit of reducing neuronal wiring length and improving cognitive function. Less understood is how the brain folds. Several hypotheses have been proposed, but none have been directly used to make testable predictions. Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences, collaborating with scientists in Finland and France, have shown that while many molecular processes are important in determining cellular events, what ultimately causes the brain to fold is a simple mechanical instability associated with buckling. The research is published in Nature Physics. Understanding how the brain folds could help unlock the inner workings of the brain and unravel brain-related disorders, as function often follows form. “We found that we could mimic cortical folding using a very simple physical principle and get results qualitatively similar to what we see in real fetal brains,” said L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, Organismic and Evolutionary Biology, and Physics. The number, size, shape, and position of neuronal cells present during brain growth all lead to the expansion of the gray matter, known as the cortex, relative to the underlying white matter. This puts the cortex under compression, leading in turn to a mechanical instability that causes it to crease locally. “This simple evolutionary innovation, with iterations and variations, allows for a large cortex to be packed into a small volume, and is likely the dominant cause behind brain folding, known as gyrification,” said Mahadevan, who is also a core faculty member of the Wyss Institute for Biologically Inspired Engineering and a member of the Kavli Institute for Bionano Science and Technology, both at Harvard University. Mahadevan’s previous research found that the growth differential between the brain’s outer cortex and the soft tissue underneath explains the variations in the folding patterns across organisms in terms of just two parameters, the relative size of the brain and the relative expansion of the cortex. Building on this, the team collaborated with neuroanatomists and radiologists in France and directly tested this theory using data from human fetuses. The team made a 3-D, gel model of a smooth fetal brain based on MRI images. The model’s surface was coated with a thin layer of elastomer gel, as an analog of the cortex. To mimic cortical expansion, the gel brain was immersed in a solvent that is absorbed by the outer layer, causing it to swell relative to the deeper regions. Within minutes of being immersed in liquid solvent, the resulting compression led to the formation of folds similar in size and shape to real brains. The extent of the similarities surprised even the researchers. “When I put the model into the solvent, I knew there should be folding but I never expected that kind of close pattern compared to human brain,” said Jun Young Chung, a postdoctoral fellow and co-first author of the paper. “It looks like a real brain.” The key to those similarities lies in the unique shape of the human brain. “The geometry of the brain is really important because it serves to orient the folds in certain directions,” said Chung. “Our model, which has the same large-scale geometry and curvature as a human brain, leads to the formation of folds that matches those seen in real fetal brains quite well.” The largest folds seen in the model gel brain are similar in shape, size, and orientation to what is seen in the fetal brain, and can be replicated in multiple gel experiments. The smallest folds are not conserved, mirroring similar variations across human brains. “Brains are not exactly the same from one human to another, but we should all have the same major folds in order to be healthy,” said Chung. “Our research shows that if a part of the brain does not grow properly, or if the global geometry is disrupted, we may not have the major folds in the right place, which may cause dysfunction in the brain.”


News Article | February 1, 2016
Site: phys.org

Why the brain is folded can be rationalized easily from an evolutionary perspective; folded brains likely evolved to fit a large cortex into a small volume with the benefit of reducing neuronal wiring length and improving cognitive function. Less understood is how the brain folds. Several hypotheses have been proposed but none have been directly used to make testable predictions. Now, researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences collaborating with scientists in Finland and France have shown that while many molecular processes are important in determining cellular events, what ultimately causes the brain to fold is a simple mechanical instability associated with buckling. The research is published in Nature Physics. Understanding how the brain folds could help unlock the inner workings of the brain and unravel brain-related disorders, as function often follows form. "We found that we could mimic cortical folding using a very simple physical principle and get results qualitatively similar to what we see in real fetal brains," said L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, Organismic and Evolutionary Biology, and Physics. The number, size, shape and position of neuronal cells during brain growth all lead to the expansion of the gray matter, known as the cortex, relative to the underlying white matter. This puts the cortex under compression, leading to a mechanical instability that causes it to crease locally. "This simple evolutionary innovation, with iterations and variations, allows for a large cortex to be packed into a small volume, and is likely the dominant cause behind brain folding, known as gyrification," said Mahadevan, who is also a core faculty member of the Wyss Institute for Biologically Inspired Engineering, and member of the Kavli Institute for Bionano Science and Technology, at Harvard University. Mahadevan's previous research found that the growth differential between the brain's outer cortex and the soft tissue underneath explains the variations in the folding patterns across organisms in terms of just two parameters, the relative size of the brain, and the relative expansion of the cortex. Building on this, the team collaborated with neuroanatomists and radiologists in France and directly tested this theory using data from human fetuses. The team made a three-dimensional, gel model of a smooth fetal brain based on MRI images. The model's surface was coated with a thin layer of elastomer gel, as an analog of the cortex. To mimic cortical expansion, the gel brain was immersed in a solvent that is absorbed by the outer layer causing it to swell relative to the deeper regions. Within minutes of being immersed in liquid solvent, the resulting compression led to the formation of folds similar in size and shape to real brains. The extent of the similarities surprised even the researchers. "When I put the model into the solvent, I knew there should be folding but I never expected that kind of close pattern compared to human brain," said Jun Young Chung, post doctoral fellow and co-first author of the paper. "It looks like a real brain." The key to those similarities lies in the unique shape of the human brain. "The geometry of the brain is really important because it serves to orient the folds in certain directions," said Chung. "Our model, which has the same large scale geometry and curvature as a human brain, leads to the formation of folds that matches those seen in real fetal brains quite well." The largest folds seen in the model gel brain are similar in shape, size and orientation to what is seen in the fetal brain, and can be replicated in multiple gel experiments. The smallest folds are not conserved, mirroring similar variations across human brains. "Brains are not exactly the same from one human to another, but we should all have the same major folds in order to be healthy," said Chung. "Our research shows that if a part of the brain does not grow properly, or if the global geometry is disrupted, we may not have the major folds in the right place, which may cause dysfunction in the brain. " Explore further: Simple origami fold may hold the key to designing pop-up furniture, medical devices and scientific tools


Home > Press > Designing a pop-up future: Simple origami fold may hold the key to designing pop-up furniture, medical devices and scientific tools Abstract: What if you could make any object out of a flat sheet of paper? That future is on the horizon thanks to new research by L. Mahadevan, the Lola England de Valpine Professor of Applied Mathematics, Organismic and Evolutionary Biology, and Physics at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS). He is also a core faculty member of the Wyss Institute for Biologically Inspired Engineering, and member of the Kavli Institute for Bionano Science and Technology, at Harvard University. Mahadevan and his team have characterized a fundamental origami fold, or tessellation, that could be used as a building block to create almost any three-dimensional shape, from nanostructures to buildings. The research is published in Nature Materials. The folding pattern, known as the Miura-ori, is a periodic way to tile the plane using the simplest mountain-valley fold in origami. It was used as a decorative item in clothing at least as long ago as the 15th century. A folded Miura can be packed into a flat, compact shape and unfolded in one continuous motion, making it ideal for packing rigid structures like solar panels. It also occurs in nature in a variety of situations, such as in insect wings and certain leaves. "Could this simple folding pattern serve as a template for more complicated shapes, such as saddles, spheres, cylinders, and helices?" asked Mahadevan. "We found an incredible amount of flexibility hidden inside the geometry of the Miura-ori," said Levi Dudte, graduate student in the Mahadevan lab and first author of the paper. "As it turns out, this fold is capable of creating many more shapes than we imagined." Think surgical stents that can be packed flat and pop-up into three-dimensional structures once inside the body or dining room tables that can lean flat against the wall until they are ready to be used. "The collapsibility, transportability and deployability of Miura-ori folded objects makes it a potentially attractive design for everything from space-bound payloads to small-space living to laparoscopic surgery and soft robotics," said Dudte. To explore the potential of the tessellation, the team developed an algorithm that can create certain shapes using the Miura-ori fold, repeated with small variations. Given the specifications of the target shape, the program lays out the folds needed to create the design, which can then be laser printed for folding. The program takes into account several factors, including the stiffness of the folded material and the trade-off between the accuracy of the pattern and the effort associated with creating finer folds - an important characterization because, as of now, these shapes are all folded by hand. "Essentially, we would like to be able to tailor any shape by using an appropriate folding pattern," said Mahadevan. "Starting with the basic mountain-valley fold, our algorithm determines how to vary it by gently tweaking it from one location to the other to make a vase, a hat, a saddle, or to stitch them together to make more and more complex structures." "This is a step in the direction of being able to solve the inverse problem - given a functional shape, how can we design the folds on a sheet to achieve it," Dudte said. "The really exciting thing about this fold is it is completely scalable," said Mahadevan. "You can do this with graphene, which is one atom thick, or you can do it on the architectural scale." ### Co-authors on the study include Etienne Vouga, currently at the University of Texas at Austin, and Tomohiro Tachi from the University of Tokyo. The work was funded by the Wyss Institute for Bioinspired Engineering, the Kavli Institute for Bionano Science and Technology, and the Harvard MRSEC. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


Holmes-Cerfon M.,Kavli Institute for Bionano Science and Technology | Aziz M.J.,Kavli Institute for Bionano Science and Technology | Brenner M.P.,Kavli Institute for Bionano Science and Technology
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

Using a theoretical analysis of the ion beam sputtering dynamics, we demonstrate how ion bombardment on an initially sloped surface can create knife-edge-like ridges on the surface. These ridges arise as nonclassical shocklike solutions that are undercompressive on both sides and appear to control the dynamics over a large range of initial conditions. The slope of the ridges is selected uniquely by the dynamics and can be up to 30 or more depending on the orientation dependence of the sputtering yield. For 1 keV Ar + on Si(001), the scale of the ridge is 2 nm. This is much smaller than the most unstable length scale and suggests a method for creating very steep, very sharp features on a surface spontaneously, by prepatterning the surface to contain relatively modest slopes on the macroscale. © 2012 American Physical Society.


Ilievski F.,Harvard University | Mazzeo A.D.,Harvard University | Shepherd R.F.,Harvard University | Chen X.,Harvard University | And 2 more authors.
Angewandte Chemie - International Edition | Year: 2011

Soft robots: A methodology based on embedded pneumatic networks (PneuNets) is described that enables large-amplitude actuations in soft elastomers by pressurizing embedded channels. Examples include a structure that can change its curvature from convex to concave, and devices that act as compliant grippers for handling fragile objects (e.g., a chicken egg). © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Grinthal A.,Harvard University | Aizenberg J.,Harvard University | Aizenberg J.,Wyss Institute for Biologically Inspired Engineering | Aizenberg J.,Kavli Institute for Bionano Science and Technology
Chemical Society Reviews | Year: 2013

A living organism is a bundle of dynamic, integrated adaptive processes: not only does it continuously respond to constant changes in temperature, sunlight, nutrients, and other features of its environment, but it does so by coordinating hierarchies of feedback among cells, tissues, organs, and networks all continuously adapting to each other. At the root of it all is one of the most fundamental adaptive processes: the constant tug of war between chemistry and mechanics that interweaves chemical signals with endless reconfigurations of macromolecules, fibers, meshworks, and membranes. In this tutorial we explore how such chemomechanical feedback-as an inherently dynamic, iterative process connecting size and time scales-can and has been similarly evoked in synthetic materials to produce a fascinating diversity of complex multiscale responsive behaviors. We discuss how chemical kinetics and architecture can be designed to generate stimulus-induced 3D spatiotemporal waves and topographic patterns within a single bulk material, and how feedback between interior dynamics and surface-wide instabilities can further generate higher order buckling and wrinkling patterns. Building on these phenomena, we show how yet higher levels of feedback and spatiotemporal complexity can be programmed into hybrid materials, and how these mechanisms allow hybrid materials to be further integrated into multicompartmental systems capable of hierarchical chemo-mechano-chemical feedback responses. These responses no doubt represent only a small sample of the chemomechanical feedback behaviors waiting to be discovered in synthetic materials, and enable us to envision nearly limitless possibilities for designing multiresponsive, multifunctional, self-adapting materials and systems. © 2013 The Royal Society of Chemistry.


Grinthal A.,Harvard University | Kang S.H.,Harvard University | Kang S.H.,Wyss Institute for Biologically Inspired Engineering | Epstein A.K.,Harvard University | And 6 more authors.
Nano Today | Year: 2012

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. © 2012 Elsevier Ltd. All rights reserved.

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