Energy News  
TECH SPACE
3-D-printed structures 'remember' their shapes
by Staff Writers
Boston MA (SPX) Aug 29, 2016


In this series, a 3-D printed multimaterial shape-memory minigripper, consisting of shape-memory hinges and adaptive touching tips, grasps a cap screw. Image courtesy Qi (Kevin) Ge. For a larger version of this image please go here.

Engineers from MIT and Singapore University of Technology and Design (SUTD) are using light to print three-dimensional structures that "remember" their original shapes. Even after being stretched, twisted, and bent at extreme angles, the structures - from small coils and multimaterial flowers, to an inch-tall replica of the Eiffel tower - sprang back to their original forms within seconds of being heated to a certain temperature "sweet spot."

For some structures, the researchers were able to print micron-scale features as small as the diameter of a human hair - dimensions that are at least one-tenth as big as what others have been able to achieve with printable shape-memory materials. The team's results were published earlier this month in the online journal Scientific Reports.

Nicholas X. Fang, associate professor of mechanical engineering at MIT, says shape-memory polymers that can predictably morph in response to temperature can be useful for a number of applications, from soft actuators that turn solar panels toward the sun, to tiny drug capsules that open upon early signs of infection.

"We ultimately want to use body temperature as a trigger," Fang says. "If we can design these polymers properly, we may be able to form a drug delivery device that will only release medicine at the sign of a fever."

Fang's coauthors include former MIT-SUTD research fellow Qi "Kevin" Ge, now an assistant professor at SUTD; former MIT research associate Howon Lee, now an assistant professor at Rutgers University; and others from SUTD and Georgia Institute of Technology.

Ge says the process of 3-D printing shape-memory materials can also be thought of as 4-D printing, as the structures are designed to change over the fourth dimension - time.

"Our method not only enables 4-D printing at the micron-scale, but also suggests recipes to print shape-memory polymers that can be stretched 10 times larger than those printed by commercial 3-D printers," Ge says. "This will advance 4-D printing into a wide variety of practical applications, including biomedical devices, deployable aerospace structures, and shape-changing photovoltaic solar cells."

Need for speed
Fang and others have been exploring the use of soft, active materials as reliable, pliable tools. These new and emerging materials, which include shape-memory polymers, can stretch and deform dramatically in response to environmental stimuli such as heat, light, and electricity - properties that researchers have been investigating for use in biomedical devices, soft robotics, wearable sensors, and artificial muscles.

Shape-memory polymers are particularly intriguing: These materials can switch between two states - a harder, low-temperature, amorphous state, and a soft, high-temperature, rubbery state. The bent and stretched shapes can be "frozen" at room temperature, and when heated the materials will "remember" and snap back to their original sturdy form.

To fabricate shape-memory structures, some researchers have looked to 3-D printing, as the technology allows them to custom-design structures with relatively fine detail. However, using conventional 3-D printers, researchers have only been able to design structures with details no smaller than a few millimeters. Fang says this size restriction also limits how fast the material can recover its original shape.

"The reality is that, if you're able to make it to much smaller dimensions, these materials can actually respond very quickly, within seconds," Fang says. "For example, a flower can release pollen in milliseconds. It can only do that because its actuation mechanisms are at the micron scale."

Printing with light
To print shape-memory structures with even finer details, Fang and his colleagues used a 3-D printing process they have pioneered, called microstereolithography, in which they use light from a projector to print patterns on successive layers of resin.

The researchers first create a model of a structure using computer-aided design (CAD) software, then divide the model into hundreds of slices, each of which they send through the projector as a bitmap - an image file format that represents each layer as an arrangement of very fine pixels. The projector then shines light in the pattern of the bitmap, onto a liquid resin, or polymer solution, etching the pattern into the resin, which then solidifies.

"We're printing with light, layer by layer," Fang says. "It's almost like how dentists form replicas of teeth and fill cavities, except that we're doing it with high-resolution lenses that come from the semiconductor industry, which give us intricate parts, with dimensions comparable to the diameter of a human hair."

The researchers then looked through the scientific literature to identify an ideal mix of polymers to create a shape-memory material on which to print their light patterns. They picked two polymers, one composed of long-chain polymers, or spaghetti-like strands, and the other resembling more of a stiff scaffold. When mixed together and cured, the material can be stretched and twisted dramatically without breaking.

What's more, the material can bounce back to its original printed form, within a specific temperature range - in this case, between 40 and 180 degrees Celsius (104 to 356 degrees Fahrenheit).

The team printed a variety of structures, including coils, flowers, and the miniature Eiffel tower, whose full-size counterpart is known for its intricate steel and beam patterns. Fang found that the structures could be stretched to three times their original length without breaking. When they were exposed to heat within the range of 40 C to 180 C, they snapped back to their original shapes within seconds.

"Because we're using our own printers that offer much smaller pixel size, we're seeing much faster response, on the order of seconds," Fang says. "If we can push to even smaller dimensions, we may also be able to push their response time, to milliseconds."

Soft grip
To demonstrate a simple application for the shape-memory structures, Fang and his colleagues printed a small, rubbery, claw-like gripper. They attached a thin handle to the base of the gripper, then stretched the gripper's claws open. When they cranked the temperature of the surrounding air to at least 40 C, the gripper closed around whatever the engineers placed beneath it.

"The grippers are a nice example of how manipulation can be done with soft materials," Fang says. "We showed that it is possible to pick up a small bolt, and also even fish eggs and soft tofu. That type of soft grip is probably very unique and beneficial."

Going forward, he hopes to find combinations of polymers to make shape-memory materials that react to slightly lower temperatures, approaching the range of human body temperatures, to design soft, active, controllable drug delivery capsules. He says the material may also be printed as soft, responsive hinges to help solar panels track the sun.

"Very often, excessive heat will build up on the back side of the solar cell, so you could use [shape-memory materials] as an actuation mechanism to tune the inclination angle of the solar cell," Fang says. "So we think there will probably be more applications that we can demonstrate."


Thanks for being here;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Contributor
$5 Billed Once


credit card or paypal
SpaceDaily Monthly Supporter
$5 Billed Monthly


paypal only


.


Related Links
Massachusetts Institute of Technology
Space Technology News - Applications and Research






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Previous Report
TECH SPACE
New approach doubles 3-D resolution of fluorescence microscopy
Washington DC (SPX) Aug 15, 2016
Researchers have developed a new fluorescence microscopy approach that significantly improves image resolution by acquiring three views of a sample at the same time. Their new method is particularly useful for watching the dynamics of biological processes, which can provide insights into how healthy cells work and what goes wrong when diseases occur. In The Optical Society's journal for hi ... read more


TECH SPACE
Chinese giant to buy Pakistani power company for $1.6 bn

Economy of energy-hungry India may face headwinds

Summer spells cold showers for Russians as hot water cut

Foreigners barred from buying Australia's largest energy grid

TECH SPACE
Extending battery life for mobile devices

Fusion facilities at PPPL and Culham, England, could provide path to limitless energy

New class of fuel cells offer increased flexibility, lower cost

Stretchy supercapacitors power wearable electronics

TECH SPACE
Annual wind report confirms tech advancements, improved performance, and low energy prices

OX2 wins EPC contract for 112 MW wind power in Norway

Wind power fiercer than expected

E.ON starts new wind farm in Texas

TECH SPACE
Solar cell is more efficient, costs less than its counterparts

U.S. capital comes up short on solar power

An effective and low-cost solution for storing solar energy

Bubble-wrapped sponge creates steam using sunlight

TECH SPACE
EDF board members sue to overturn Hinkley Point plan

Philippines eyes reviving mothballed nuclear plant

Iran to build two nuclear plants with Russia: official

French state, EDF strike deal to close nuclear plant

TECH SPACE
Scientists solve puzzle of converting gaseous carbon dioxide to fuel

Biofuels not as 'green' as many think

Biofuels could increase rather than decrease C02 emissions

Biochemists describe light-driven conversion of greenhouse gas to fuel

TECH SPACE
China unveils Mars probe, rover for ambitious 2020 mission

China Ends Preparatory Work on Long March 5 Next-Generation Rocket Engine

China launches hi-res SAR imaging satellite

China launches world first quantum satellite

TECH SPACE
Plants less thirsty as climate warms: study

Humans have caused climate change for 180 years

Global climate models do not easily downscale for regional predictions

'Baby, it's hot outside': Why birds sing to eggs









The content herein, unless otherwise known to be public domain, are Copyright 1995-2024 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. General Data Protection Regulation (GDPR) Statement Our advertisers use various cookies and the like to deliver the best ad banner available at one time. All network advertising suppliers have GDPR policies (Legitimate Interest) that conform with EU regulations for data collection. By using our websites you consent to cookie based advertising. If you do not agree with this then you must stop using the websites from May 25, 2018. Privacy Statement. Additional information can be found here at About Us.