Nav: Home

'Peel-and-go' printable structures fold themselves

September 13, 2017

As 3-D printing has become a mainstream technology, industry and academic researchers have been investigating printable structures that will fold themselves into useful three-dimensional shapes when heated or immersed in water.

In a paper appearing in the American Chemical Society's journal Applied Materials and Interfaces, researchers from MIT's Computer Science and Artificial Intelligence Laboratory (CSAIL) and colleagues report something new: a printable structure that begins to fold itself up as soon as it's peeled off the printing platform.

One of the big advantages of devices that self-fold without any outside stimulus, the researchers say, is that they can involve a wider range of materials and more delicate structures.

"If you want to add printed electronics, you're generally going to be using some organic materials, because a majority of printed electronics rely on them," says Subramanian Sundaram, an MIT graduate student in electrical engineering and computer science and first author on the paper. "These materials are often very, very sensitive to moisture and temperature. So if you have these electronics and parts, and you want to initiate folds in them, you wouldn't want to dunk them in water or heat them, because then your electronics are going to degrade."

To illustrate this idea, the researchers built a prototype self-folding printable device that includes electrical leads and a polymer "pixel" that changes from transparent to opaque when a voltage is applied to it. The device, which is a variation on the "printable goldbug" that Sundaram and his colleagues announced earlier this year, starts out looking something like the letter "H." But each of the legs of the H folds itself in two different directions, producing a tabletop shape.

The researchers also built several different versions of the same basic hinge design, which show that they can control the precise angle at which a joint folds. In tests, they forcibly straightened the hinges by attaching them to a weight, but when the weight was removed, the hinges resumed their original folds.

In the short term, the technique could enable the custom manufacture of sensors, displays, or antennas whose functionality depends on their three-dimensional shape. Longer term, the researchers envision the possibility of printable robots.

Sundaram is joined on the paper by his advisor, Wojciech Matusik, an associate professor of electrical engineering and computer science (EECS) at MIT; Marc Baldo, also an associate professor of EECS, who specializes in organic electronics; David Kim, a technical assistant in Matusik's Computational Fabrication Group; and Ryan Hayward, a professor of polymer science and engineering at the University of Massachusetts at Amherst.

Stress relief

The key to the researchers' design is a new printer-ink material that expands after it solidifies, which is unusual. Most printer-ink materials contract slightly as they solidify, a technical limitation that designers frequently have to work around.

Printed devices are built up in layers, and in their prototypes the MIT researchers deposit their expanding material at precise locations in either the top or bottom few layers. The bottom layer adheres slightly to the printer platform, and that adhesion is enough to hold the device flat as the layers are built up. But as soon as the finished device is peeled off the platform, the joints made from the new material begin to expand, bending the device in the opposite direction.

Like many technological breakthroughs, the CSAIL researchers' discovery of the material was an accident. Most of the printer materials used by Matusik's Computational Fabrication Group are combinations of polymers, long molecules that consist of chainlike repetitions of single molecular components, or monomers. Mixing these components is one method for creating printer inks with specific physical properties.

While trying to develop an ink that yielded more flexible printed components, the CSAIL researchers inadvertently hit upon one that expanded slightly after it hardened. They immediately recognized the potential utility of expanding polymers and began experimenting with modifications of the mixture, until they arrived at a recipe that let them build joints that would expand enough to fold a printed device in half.

Whys and wherefores

Hayward's contribution to the paper was to help the MIT team explain the material's expansion. The ink that produces the most forceful expansion includes several long molecular chains and one much shorter chain, made up of the monomer isooctyl acrylate. When a layer of the ink is exposed to ultraviolet light -- or "cured," a process commonly used in 3-D printing to harden materials deposited as liquids -- the long chains connect to each other, producing a rigid thicket of tangled molecules.

When another layer of the material is deposited on top of the first, the small chains of isooctyl acrylate in the top, liquid layer sink down into the lower, more rigid layer. There, they interact with the longer chains to exert an expansive force, which the adhesion to the printing platform temporarily resists.

The researchers hope that a better theoretical understanding of the reason for the material's expansion will enable them to design material tailored to specific applications -- including materials that resist the 1-3 percent contraction typical of many printed polymers after curing.
-end-
Additional background

PAPER: 3D-printed self-folding electronics http://web.mit.edu/subras/www/ACS_AMI_17.pdf

ARCHIVE: Toward printable, sensor-laden "skin" for robots http://news.mit.edu/2017/goldbug-beetle-printable-sensor-laden-skin-robots-0323

ARCHIVE: Customizing 3-D printing http://news.mit.edu/2015/customizing-3-d-printing-0903

ARCHIVE: "MultiFab" 3-D prints a record 10 materials at once, no assembly required http://news.mit.edu/2015/multifab-3-d-print-10-materials-0824

ARCHIVE: Bake your own robot http://news.mit.edu/2014/bake-your-own-robot-0530

Massachusetts Institute of Technology

Related Polymer Articles:

World first: New polymer goes for a walk when illuminated
Scientists have developed a new material that can undulate and therefore propel itself forward under the influence of light.
Polymer-coated silicon nanosheets -- an alternative to graphene
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene.
New polymer additive could revolutionize plastics recycling
Only 2 percent of the 78 million tons of manufactured plastics are currently recycled into similar products because polyethylene (PE) and polypropylene (PP), which account for two-thirds of the world's plastics, have different chemical structures and cannot be efficiently repurposed together.
Responsive filtration membranes by polymer self-assembly
Polymer self-assembly is a crucial tool for manufacturing membranes using scalable methods, enabling easier commercialization.
Biodegradable polymer coating for implants
Medical implants often carry surface substrates that release active substances or to which biomolecules or cells can adhere better.
Praise for polymer science
Engineer Glenn Fredrickson receives the William H. Walker Award for Excellence in Contributions to Chemical Engineering Literature.
When it comes to polymer fragility, size does matter
By combining a number of tools and techniques, a team of researchers from the US, Italy and China was able to find a more complete picture of the glass transition phenomenon in polymers and to point out where the polymers differ from small molecular liquids.
Better, stronger: Polymer breakthrough to improve things we use everyday
Medicine, mobile phones, computers and clothes could all be enhanced using the process for making paint, according to research by the University of Warwick.
CWRU researcher scaling up knotty polymer research
Researchers at Case Western Reserve University developed a technique that produces a long chain molecule in the shape of a trefoil knot.
New 3-D printed polymer can convert methane to methanol
Lawrence Livermore National Laboratory scientists have combined biology and 3-D printing to create the first reactor that can continuously produce methanol from methane at room temperature and pressure.

Related Polymer Reading:

The Polymer Clay Techniques Book
by Sue Heaser (Author)

Everyone can achieve great results with polymer clay. With the 50+ techniques in this book, readers can create polymer clay buttons or boxes or anything in between. Starting with the very basics (such as rolling, baking and gluing), it then moves on to more advanced methods: marbling, texturing, millefiori, bead-making, faux-stone effects and more. Feature spreads show exciting ways to combine techniques. A comprehensive guide to the medium, complete with everything from a listing of necessary tools and materials to inspiring examples of polymer clay art. View Details


Introduction to Polymers, Third Edition
by Robert J. Young (Author), Peter A. Lovell (Author)

Thoroughly updated, Introduction to Polymers, Third Edition presents the science underpinning the synthesis, characterization and properties of polymers. The material has been completely reorganized and expanded to include important new topics and provide a coherent platform for teaching and learning the fundamental aspects of contemporary polymer science.

New to the Third Edition
Part I
This first part covers newer developments in polymer synthesis, including ‘living’ radical polymerization, catalytic chain transfer and... View Details


Getting Started with Polymer
by Arshak Khachatrian (Author)

Explore the whole new world of web development and create responsive web apps using Polymer

About This BookGet to grips with the principles of Material Design and Google Web componentsMake full use of the Polymer Designer Tool, Polymer Starter Kit, and Dart to create responsive web appsAn in-depth guide with real-life examples so you can learn everything you need to know about PolymerWho This Book Is For

If you are a beginner-level web developer who would like to learn the concepts of web development using the Polymer library, then this is the book for you. Knowledge of... View Details


Polymer Physics (Chemistry)
by M. Rubinstein (Author), Ralph H. Colby (Author)

Polymer Physics thoroughly details the fundamental concepts of polymer melts, solutions, and gels in terms of both static structure and dynamics. It goes beyond other introductory polymer texts, deriving the essential tools of the physical polymer chemist or engineer without skipping any steps.

The book is divided into four parts. Part One summarizes the necessary concepts of a first course on polymers and covers the conformations of single polymer chains. Part Two deals with the thermodynamics of polymer solutions and melts, including chain conformations in those states. Part... View Details


The Polymers
by Adam Dickinson (Author)

The Polymers is a bold and brilliant new work from one of our most ambitious poetic minds. Structured as an imaginary science project, the varied pieces in this collection investigate the intersection of poetry and chemicals, specifically plastics, attempting to understand their essential role in culture. Through various procedures, constraints, and formal mutations, the poems express the repeating structures fundamental to plastic molecules as they appear in cultural and linguistic behaviours such as arguments, anxieties, and trends. Adam Dickinson’s poems challenge our... View Details


Polymers (Oxford Chemistry Primers)
by David J. Walton (Author), J. Phillip Lorimer (Author)

Here is the definitive introduction to polymer chemistry. This lively book takes the reader through the historical beginnings of polymers, the development of high-tonnage materials in the early part of the twentieth century, and on to the most modern high-performance materials available today. The authors are both experience educators and practitioners within the polymer industry and are uniquely qualified to discuss basic academic principles of polymers as well as their commercial application. Unlike other texts in this area, it successfully describes the exciting principles and varied... View Details


Polymer Chemistry, Second Edition
by Paul C. Hiemenz (Author), Timothy P. Lodge (Author)

“Highly recommended!” – CHOICE

New Edition Offers Improved Framework for Understanding Polymers

Written by well-established professors in the field, Polymer Chemistry, Second Edition provides a well-rounded and articulate examination of polymer properties at the molecular level. It focuses on fundamental principles based on underlying chemical structures, polymer synthesis, characterization, and properties.

Consistent with the previous edition, the authors emphasize the logical progression of concepts, rather than presenting just a catalog of... View Details


Kawaii Polymer Clay Creations: 20 Super-Cute Miniature Projects
by Emily Chen (Author)

Learn to make super-cute polymer clay animals and food in Kawaii Polymer Clay Creations!

Emily Chen teaches you how to craft twenty adorable figures from basic shapes using easy polymer clay techniques and tools. Progress from a simple bunny to an elaborate unicorn, and learn now to make miniature cookies, bread and ice cream cones that look delicious enough to eat! Included are basic jewelry techniques for transforming your polymer clay masterpieces into wearable items. Try turning a cat into a charm, a pig into a bracelet, a cupcake into a pair of earrings or a stack of... View Details


Creating Lifelike Figures in Polymer Clay: Tools and Techniques for Sculpting Realistic Figures
by Katherine Dewey (Author)

Katherine Dewey’s expressive and elegantly detailed sculptures enchant all who see them. With the magical medium of polymer clay and this book, you can follow in her footsteps.
 
Thorough instructions supported by more than 400 step-by-step color photos and 200 detailed drawings cover the entire process of sculpting realistic figures. Easy-to-read maps of the figure illustrate the landmarks of the body, while scale diagrams indicate the simple shapes hidden within the human form, as well as how to combine and model those shapes.
 
For anyone who loves fantasy, romance,... View Details


Developing Web Components: UI from jQuery to Polymer
by Jarrod Overson (Author), Jason Strimpel (Author)

Although web components are still on the bleeding edge—barely supported in modern browsers—the technology is also moving extremely fast. This practical guide gets you up to speed on the concepts underlying W3C’s emerging standard and shows you how to build custom, reusable HTML5 Web Components.

Regardless of your experience with libraries such as jQuery and Polymer, this book teaches JavaScript developers the DOM manipulations these libraries perform. You’ll learn how to build a basic widget with vanilla JavaScript and then convert it into a web component that’s semantic,... View Details

Best Science Podcasts 2017

We have hand picked the best science podcasts for 2017. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Simple Solutions
Sometimes, the best solutions to complex problems are simple. But simple doesn't always mean easy. This hour, TED speakers describe the innovation and hard work that goes into achieving simplicity. Guests include designer Mileha Soneji, chef Sam Kass, sleep researcher Wendy Troxel, public health advocate Myriam Sidibe, and engineer Amos Winter.
Now Playing: Science for the People

#448 Pavlov (Rebroadcast)
This week, we're learning about the life and work of a groundbreaking physiologist whose work on learning and instinct is familiar worldwide, and almost universally misunderstood. We'll spend the hour with Daniel Todes, Ph.D, Professor of History of Medicine at The Johns Hopkins University, discussing his book "Ivan Pavlov: A Russian Life in Science."