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‘Pop-Up’ 3D structures can mimic brain circuits

pop-up-3d-structures

A 3D silicon microstructure. (J. Rogers, University of Illinois)

By mimicking children’s pop-up books, scientists can now make complex microscopic 3D shapes that model brain circuitry and blood vessels, researchers say.

These intricate structures, which could resemble tiny flowers and peacocks, may one day help scientists electronically control living tissue, the researchers added.

Naturally curved, thin and flexible 3D structures are common in biology; examples include the circuits of brain cells and networks of veins. Materials scientist John Rogers, at the University of Illinois at Urbana-Champaign, and his colleagues want to create similarly complex devices that can wrap around these biological structures, potentially supporting or improving their function. [5 Crazy Technologies That Are Revolutionizing Biotech]

“Our focus has been on the brain, heart and skin,” Rogers said.

Devices that mimic the complex structures found in nature are very difficult to manufacture on microscopic scales. But now, Rogers and his colleagues have developed a simple strategy for such manufacture that involves flat 2D structures that pop up into 3D shapes.

“The analogy would be children’s pop-up books,” Rogers told Live Science.

To manufacture these structures, the scientists fabricate 2D patterns of ribbons on stretched elastic silicone rubber. In experiments, the ribbons were as small as 100 nanometers wide, or about 1,000 times thinner than the average human hair, and could be made from a variety of materials, including silicon and nickel.

The 2D patterns are designed so that there are both strong and weak points of stickiness between the patterns and the silicone rubber they sit on. After the scientists fabricate the 2D designs, they release the tension on the silicone rubber. The weak points of stickiness break away, “and up pops a 3D structure,” study co-author Yonggang Huang, a professor of mechanical engineering at Northwestern University in Evanston, Illinois, said in a statement. “In just one shot, you get your structure.”

The researchers generated more than 40 different geometric designs, from single and multiple spirals and rings to spherical baskets, cubical boxes, peacocks, flowers, tents, tables and starfish. Scientists could even arrange patterns with multiple layers, a bit like multi-floor buildings.

This new pop-up technique has many advantages, the investigators said. The strategy is fast, inexpensive and can employ many different materials used in electronics today to build a wide variety of microscopic structures. Moreover, researchers can build many different structures at one time, and incorporate different materials into hybrid structures.

“We are excited about the fact that these simple ideas and schemes provide immediate paths to broad and previously inaccessible classes of 3D micro- and nano-structures in a way that is compatible with the highest-performance materials and processing techniques available,” Rogers said. “We feel that the findings have potential relevance to a wide range of microsystems technologies biomedical devices, optoelectronics, photovoltaics, 3D circuits, sensors and so on.”

The scientists said their pop-up assembly technique has many advantages over3D printers, which create 3D structures by depositing layers of material on top of one another. Although 3D printers are increasingly popular, they work slowly. In addition, it is difficult for 3D printers to build objects using more than one material, and it is nearly impossible for these printers to produce semiconductors or single crystalline metals, the researchers said.

Still, Rogers emphasized the team’s new strategy is complementary to 3D printing, and is not an attempt to replace that technique.

The scientists are currently using this pop-up assembly strategy to build electronic scaffolds that can monitor and control the growth of cells in lab experiments, Rogers said. “We are also using these ideas to form helical, springy metal interconnect coils and antennas for soft electronic devices designed to integrate with the human body,” he said.

The scientists detailed their findings online Jan. 8 in the journal Science.

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Snake robots! Slithering machines could aid search-and-rescue efforts

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The Carnegie Mellon snake robot has finally mastered the art of slithering up a sandy slope. (Nico Zevallos and Chaohui Gong)

One snake’s ability to shimmy up slippery sand dunes could inspire new technologies for robots that could perform search and rescue missions, carry out inspections of hazardous wastes and even explore ancient pyramids.

A new study looked at the North American desert-dwelling sidewinder rattlesnake (Crotalus cerastes), a creature better known for its venomous bite than its graceful movements. But this snake can climb up sandy slopes without sliding back down to the bottom a feat that few snake species can accomplish.

Snakelike, or limbless, robots are intriguing to scientists for several reasons. First, their lack of legs, wheels or tracks means they don’t often get stuck in ruts or held up by bumps in their path. They could also be used to access areas that other bots can’t get to, or to explore places that aren’t safe for humans. [Biomimicry: 7 Clever Technologies Inspired by Nature]

The sidewinder shimmy

To get a closer look at their live study subjects, the researchers headed to Zoo Atlanta, where they were able to examine six sidewinder rattlesnakes. They tested the snakes on a specially designed inclined table covered with loosely packed sand.

Fifty-four trials were conducted, with each of the six snakes slithering up the sandy table nine times, three times each at varying degrees of steepness. As the snakes worked their way up the makeshift sand dune, high-speed cameras tracked their movements, taking note of exactly where their bodies came into contact with the sand as they moved upward.

The researchers found that sidewinder snakes live up to their name. The slithery creatures moved up the sandy incline in a sideways motion, with their heads pointing toward the top of the incline and the rest of their bodies moving horizontally up the slope. The researchers then looked more carefully at how sidewinders carry out these complex movements.

“The snakes tended to increase the amount of body in contact with the surface at any instant in time when they were sidewinding up the slope and the incline angle increased,” said Daniel Goldman, co-author of the study and an associate professor of biomechanics at the Georgia Institute of Technology in Atlanta. Specifically, the snakes doubled the amount of their bodies touching the sand when navigating the slope, he added.

And the parts of the snake’s body that were touching the sand during the ascent never slipped back down the slope because the creature applied the right amount of force in its movements, keeping the sand under it from sliding, Goldman told Live Science.

Snake robots

To put their newfound understanding of sidewinding to good use, Goldman and his colleagues got in touch with Howie Choset, a professor at The Robotics Institute at Carnegie Mellon University in Pittsburgh. Choset, who has been developing limbless robots for years, already developed a snakelike bot that performs well both in the lab and in real-life situations. However, his slithering machine has run into one particular problem during field tests.

“These guys have been making a robot sidewind for years over a wide diversity of substrates, but they had a lot of trouble on sandy slopes,” Goldman said.

To get the robot moving over sandy dunes, the researchers applied what they now know about the sidewinding rattlesnake’s patterns of movement. They programmed the robot so that more of its body would come into contact with the ground as it slides up the slope. They also applied what they had learned about force, which enables the robot to move its weight in such a way that it keeps moving upward over the sand without rolling back down the slope.

Now that Choset’s snake robot can move over tough terrain, it’ll be better equipped to handle the tasks that it was built to tackle.

“Since these robots have a narrow cross section and they’re relatively smooth, they can fit into places that people and machinery can’t otherwise access,” Choset told Live Science.

For example, these limbless robots could be used during search-and-rescue missions, since the slithery machines can crawl into a collapsed building and search for people trapped inside without disturbing the compromised structure. The snake bot could also be sent into containers that may hold dangerous substances, such as nuclear waste, to take samples and report back to hazmat specialists.

Choset also said these robotic sidewinding abilities could come in handy on archaeological sites. For instance, the robots could one day be used to explore the insides of pyramids or tombs, he said.

The research represents a key collaboration between biologists and roboticists, said Auke Ijspeert, head of the Biorobotics Laboratory at the Swiss Federal Institute of Technology at Lausanne (EPFL), who was not involved in the new study.

“I think its a very exciting project which managed to contribute to the two objectives of biorobotics,” Ijspeert told Live Science.

“On one hand, they took inspiration from biology to design better control methods for the robot,” Ijspeert said. “By looking at how sidewinding takes place in a snake, especially with slopes, they found out the strategy that the animal uses and, when they tested it on the robot, it could really improve the climbing capabilities of the robot.”

The researchers also achieved the second goal of biorobotics, he said, which is to use a robot as a scientific tool. By testing the different speeds at which the robotic snake could successfully climb up the sand, the researchers were able to pinpoint exactly how fast real snakes make their way up these slippery slopes.

“It’s a nice example of how robots can help in biology and how biology can help in robotics.”

The study was published online Oct. 9 in the journal Science.

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Secret second code found hiding within human DNA

Secret second code found hiding within human DNA

Published December 13, 2013

news.com.au
  • dna molecules.jpg
    AP GRAPHICSBANK

Scientists have long believed that DNA tells the cells how to make proteins. But the discovery of a new, second DNA code overnight suggests the body speaks two different languages.

The findings in the journal Science may have big implications for how medical experts use the genomes of patients to interpret and diagnose diseases, researchers said.

The newfound genetic code within deoxyribonucleic acid, the hereditary material that exists in nearly every cell of the body, was written right on top of the DNA code scientists had already cracked.

‘A basic assumption about reading the human genome missed half of the picture.’

– John Stamatoyannopoulos, University of Washington associate professor of genome sciences and of medicine

Rather than concerning itself with proteins, this one instructs the cells on how genes are controlled.

Its discovery means DNA changes, or mutations that come with age or in response to viruses, may be doing more than what scientists previously thought, he said.

“For over 40 years we have assumed that DNA changes affecting the genetic code solely impact how proteins are made,” said lead author John Stamatoyannopoulos, University of Washington associate professor of genome sciences and of medicine.

“Now we know that this basic assumption about reading the human genome missed half of the picture,” he said.

“Many DNA changes that appear to alter protein sequences may actually cause disease by disrupting gene control programs or even both mechanisms simultaneously.”

Scientists already knew that the genetic code uses a 64-letter alphabet called codons.

But now researchers have figured out that some of these codons have two meanings. Coined duons, these new elements of DNA language have one meaning related to protein sequence and another that is related to gene control.

The latter instructions “appear to stabilise certain beneficial features of proteins and how they are made,” the study said.

The discovery was made as part of the international collaboration of research groups known as the Encyclopedia of DNA Elements Project, or ENCODE.

It is funded by the US National Human Genome Research Institute with the goal of finding out where and how the directions for biological functions are stored in the human genome.

Get more science and technology news at news.com.au.

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