Monthly Archives: November 2016

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See-Through Robot Grab a Live Goldfish

Squishy, nearly transparent robots that flap, squeeze and kick when pumped with water could be the next underwater spies, at least when it comes to sneaking up on aquatic life.

In a robotic test, one of these jelly-like machines was quick enough to grab and release a goldfish, a team at the Massachusetts Institute of Technology found.

The researchers, led by engineer Xuanhe Zhao and graduate student Hyunwoo Yuk, created a series of the transparent robots from a rubbery material called hydrogel, including a fin-like bot that can flap back and forth, a “limb” that can kick, and a hand-shaped structure that can squeeze and let go.

Because the material is composed mostly of water, the resulting robotscould also have biomedical applications, the researchers said.

“Hydrogels are soft, wet, biocompatible and can form more friendly interfaces with human organs,” Zhao, an associate professor of mechanical engineering and civil and environmental engineering, said in a statement. He added that the group is collaborating with medical scientists to create soft “hands,” which could aid in delicately manipulating tissues and organs during surgeries.

For five years, Zhao’s team worked to whip up various hydrogel mixes, made from polymers and water, to find one that was tough and stretchable. They also developed processes to attach, or glue, the hydrogels to an array of surfaces, such as glass, metal and rubber.

Zhao noted that others have tried to craft soft robotics from hydrogels, but their materials were brittle and not very flexible, resulting in cracks after repeated use.

When brainstorming ways to create soft robots from their hydrogels, the researchers looked to nature, particularly at glass eels; these tiny, transparent larvae are soft like hydrogels and manage to migrate unscathed over long distances to their riverine habitats.

“It is extremely long travel, and there is no means of protection,” Yuk said in the statement. “It seems they tried to evolve into a transparent form as an efficient camouflage tactic. And we wanted to achieve a similar level of transparency, force and speed.”

So the team got to work. They used 3D printing and laser-cutting techniques to create hollow components of robots. Then, they attached these units to small, rubbery tubes connected to pumps.

Depending on the overall shape of each robot, when water was pumped in, it would quickly produce forceful motions, such as curling up or stretching out.

In one test, Zhao’s team pumped water into and out of the “fingers” of a hand-like robot while submerging it in a goldfish tank. The grasper closed delicately around the fish, the researchers said.

“[The robot] is almost transparent, very hard to see,” Zhao said in the statement. “When you release the fish, it’s quite happy because [the robot] is soft and doesn’t damage the fish. Imagine a hard robotic hand would probably squash the fish.”

The team is now dreaming up various applications for the hydrogel robots, while also playing around with the hydrogel recipe to customize it for particular uses; a robot used in the medical field, for instance, may not need to be completely transparent, while another application might require a stiffer hydrogel, they said.

“We want to pinpoint a realistic application and optimize the material to achieve something impactful,” Yuk said. “To our best knowledge, this is the first demonstration of hydrogel pressure-based actuation. We are now tossing this concept out as an open question, to say, ‘Let’s play with this.'”

Their research — funded in part by the Office of Naval Research, the MIT Institute for Soldier Nanotechnologies and the National Science Foundation — was published online Feb. 1 in the journal Nature Communications.

Other co-authors of the paper included MIT scientists Shaoting Lin, Chu Ma and Mahdi Takaffoli, as well as Nicholas X. Fang, an associate professor of mechanical engineering at MIT.

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The Exosuit Fabric Could Boost Mobility

Knitting and weaving artificial muscles could help create soft exoskeletons that people with disabilities could wear under their clothes to help them walk, according to new research.

Textile processing is one of humanity’s oldest technologies, but in recent years there has been renewed interest in using it to create “smart” textiles that can do everything from harvest power from the environment to monitor our health.

Now, Swedish researchers have created actuators — devices that convert energy into motion — from cellulose yarn coated with a polymer that reacts to electricity. These fibers were then woven and knitted using standard industrial machines to create textile actuators, dubbed “textuators” by the researchers.

Exoskeletons can be used to boost humans’ weight-lifting abilities or help the disabled walk, but they rely on electric motors or pneumatic systems that are bulky, noisy and stiff. The researchers say their approach could one day help mass-produce soft and silent exoskeletons using textile-processing technology, as well as actuators for soft robotics.

“Our dream is suits you can wear under your clothing — hidden exoskeletons to help the elderly, help those recovering from injury, maybe one day make disabled people walk again,” said Edwin Jager, an associate professor in applied physics at Linköping University in Sweden, who led the research.

The team started with cellulose yarn, which is biocompatible and renewable, and knitted and weaved it into a variety of textiles. These textiles were then coated with a conducting polymer called polypyrrole (PPy) using a process similar to how commercial fabrics are dyed.

PPy has been widely used to create soft actuators because it changes its size when a low voltage is applied to it, thanks to ions and solvents moving in and out of the polymer matrix. As this material coats the fiber, it contracts when a positive voltage is applied and expands when a negative voltage is applied.

In a new study published online today (Jan. 25) in the journal Science Advances, the researchers found that weaving the fabric resulted in a textuator that produced high force, while knitting resulted in less force but an extremely stretchy material.

By varying the processing method and the weaving or knitting pattern, Jager told Live Science it should be possible to tailor the force and strain characteristics of a textuator to the specific application at hand. To demonstrate the capabilities of the approach, the scientists integrated a knitted fabric into a Lego lever arm and it was able to lift 0.07 ounces (2 grams) of weight.

Xing Fan, an associate professor of chemical engineering at Chongqing University in China, who also works on smart textiles, told Live Science the research was an interesting step toward commercially viable smart textile actuators, but added that there are still some issues to be overcome.

At present, the material still needs to be submerged in a liquid electrolyte, which serves as a source of ions for the PPy. The material also responds much more slowly than mammalian muscle, taking minutes to fully expand or contract.

“Nevertheless, I believe that after years of improvement, the day that a feasible smart textile actuator appears on the desk of a commercial investor is not far away,” Fan told Live Science.

Jager said his group is already designing a second generation of textuators that will address these issues. Decreasing response time is simply a matter of reducing the diameter of the yarn to a few micrometers he said, which commercially available textile-processing machines are capable of doing. The researchers are also working on ways to embed the electrolyte in the fabric so that it can operate in air.

The group chose to work with PPy because it was a material they were familiar with, but a limitation is that achieving high force requires thick yarns, which slows response times. Jager said a key innovation was demonstrating that organizing multiple yarns in parallel — just like muscle fibers — was able to increase force without increasing response times.

“We don’t see ourselves locked to this material, though; it’s more a way of showing that we can use textiles with smart materials to create textuators,” he said. “I’m not sure if ours is the best material, but hopefully, people who find better materials will be inspired and use this technique of ours as a starting point and improve from it.”

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Bat Bot Acrobatics Robots

Whether they’re swooping around to catch dinner or delicately hanging upside down to sleep, bats are known for their acrobatic prowess. Now, scientists have created a robot inspired by these flying creatures. Dubbed the “Bat Bot,” it can fly, turn and swoop like its real-life counterpart in the animal kingdom.

Since at least the time of Leonardo da Vinci, scientists have sought to mimic the acrobatic way in which bats maneuver the sky. Someday, robotic bats could help deliver packages or inspect areas ranging from disaster zones to construction sites, the researchers said.

“Bat flight is the Holy Grail of aerial robotics,” said study co-author Soon-Jo Chung, a robotics engineer at the California Institute of Technology and a research scientist at NASA’s Jet Propulsion Laboratory, both in Pasadena.

Bats may possess the most sophisticated wings in the animal kingdom, with more than 40 joints in their wings that enable unparalleled agility during flight, likely so that they can pursue equally nimble insect prey, the researchers said.

“Whenever I see bats make sharp turns or perch upside down with elegant wing movements, I get mesmerized,” Chung told Live Science.

Previous work has developed a variety of flying robots biologically inspired by insects and birds. However, attempts to build robots that mimic bats have been met with limited success because of the complexities of bats’ wings, such as their multitude of joints, the researchers said.

Now, Chung and his colleagues have developed the “Bat Bot,” or B2, a robot that can fly, turn and swoop like a bat. The aim is “to build a safe, energy-efficient, soft-winged robot,” Chung told Live Science.

The researchers said previous bat robots followed the skeletal anatomy of these flying creatures too closely, resulting in bots that were too bulky to fly. Instead, the scientists figured out which components were key to the beating of a bat’s wing — the shoulder, elbow and wrist joints, and the side-to-side swish of their thighs — and used only those in their robot.

Whereas conventional flapping-wing robots used rigid wings, the Bat Bot has thin, elastic wings. “When a bat flaps its wings, it’s like a rubber sheet — it fills up with air and deforms,” said study co-author Seth Hutchinson, a robotics engineer at the University of Illinois at Urbana-Champaign. During the downward stroke, “the flexible wing fills up with air, and at the bottom of the downstroke, it flexes back into place and expels the air, which generates extra lift,” he explained. “That gives us extra flight time.”

The Bat Bot’s wings are made of bones of carbon fiber and ball-and-socket joints composed of 3D-printed plastic, all covered with a soft, durable, ultrathin, silicone-based skin only 56 microns thick. (For comparison, the average human hair is about 100 microns thick.)

The robot flapped its wings up to 10 times per second using micro-motors in its backbone. The Bat Bot weighed only about 3.3 ounces (93 grams) and had a wingspan of about 18.5 inches (47 centimeters) — measurements similar to those of Egyptian fruit bats, Chung said.

In experiments, the Bat Bot could fly at speeds averaging 18.37 feet per second (5.6 meters per second). It could also carry out sharp turns and straight dives, reaching speeds of 45.9 feet per second (14 m/s) while swooping down.

The researchers said their robot’s softness and light weight make it safer for use around humans than, for example, the quadrotor drones that are popular commercially. For instance, the Bat Bot would cause little or no damage if it were to crash into humans or other obstacles in its environment, they said. In contrast, quadrotors spin their rotor blades at high speeds of up to 18,000 revolutions per minute, which could result in dangerous interactions, Chung said.

“The high-speed rotor blades of quadrotors and other craft are inherently unsafe for humans,” Chung said. “Our Bat Bot is considerably more safe.”

The safer, more agile nature of the Bat Bot could enable a wide range of applications. For instance, Bat Bots could serve as “aerial service robots at home or in hospitals to help the elderly or disabled by quickly fetching small objects, relaying audio and video from various distant locations without requiring hard-mounting of multiple cameras, and becoming fun, pet-like companions,” Hutchinson told Live Science.

Another potential application for Bat Bots would be “to supervise construction sites,” Hutchinson said. “The need for automation in construction through advances in computer science and robotics has been highlighted by the National Academy of Engineering as one of the grand challenges of engineering in the 21st century,” he noted.

The dynamic and complex nature of construction sites has prevented the deployment of fully, or even partially, robotic and automated solutions to monitor them. “Keeping track of whether a building is put together in the right way and at the right time is an important problem, and it’s not a trivial problem — a lot of money gets spent on that in the construction industry,” Hutchinson said. Instead, Bat Bots could “fly around, pay attention and compare the building information model to the actual building that’s being constructed,” he added.

Bat Bots could also help inspect disaster zones and other areas. “For example, an aerial robot equipped with a radiation detector, 3D camera system, and temperature and humidity sensors could inspect something like the Fukushima nuclear reactors [in Japan], where the radiation level is too high for humans, or fly into tight crawl spaces, such as mines or collapsed buildings,” Hutchinson said. “Such highly maneuverable aerial robots, with longer flight endurance and range than quadrotors have, will make revolutionary advances in monitoring and recovery of critical infrastructure such as nuclear reactors, power grids, bridges and borders.”

Moreover, the Bat Bot could shed light on some of the mysteries of bat flight. Currently, researchers analyze how bats fly with video, but with the Bat Bot, researchers could develop better models of the aerodynamic forces that bats experience “beyond what can be observed with just the eyes,” Hutchinson said.

The researchers noted that the Bat Bot cannot carry heavy objects yet, but future versions of the robotic bat could lead to “drone-enabled package delivery,” Chung said.

Future research could achieve other aspects of bat flight, such as hovering or perching right side up or even upside down, the researchers said. Perching is more energy-efficient than hovering, “since stationary hovering is difficult for quadrotors in the presence of even mild wind, which is common for construction sites,” Chung said.

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A RoboDragonfly

Scientists look to flying animals — birds, bats and insects — for inspiration when they design airborne drones. But researchers are also investigating how to use technology to interact with, and even guide, animals as they fly, enhancing the unique adaptations that allow them to take to the air.

To that end, engineers have fitted dragonflies with tiny, backpack-mounted controllers that issue commands directly to the neurons controlling the insects’ flight.

This project, known as DragonflEye, uses optogenetics, a technique that employs light to transmit signals to neurons. And researchers have genetically modified dragonfly neurons to make them more light-sensitive, and thereby easier to control through measured light pulses.

Dragonflies have large heads, long bodies and two pairs of wings that don’t always flap in sync, according to a 2007 study published in thejournal Physical Review Letters. The study authors found that dragonflies maximize their lift when they flap both sets of wings together, and they hover by flapping their wing pairs out of synch, though at the same rate.

Meanwhile, separate muscles controlling each of their four wings allow dragonflies to dart, hover and turn on a dime with exceptional precision, scientists found in 2014. Researchers used high-speed video footage to track dragonfly flight and build computer models to better understand the insects’ complex maneuvers, presenting their findings at the 67th Annual Division of Fluid Dynamics meeting, according to a statement released by the American Physical Society in November 2014.

DragonflEye sees these tiny flight masters as potentially controllable flyers that would be “smaller, lighter and stealthier than anything else that’s manmade,” Jesse Wheeler, a biomedical engineer at the Charles Stark Draper Laboratory (CSDL) in Massachusetts and principal investigator on the DragonflEye program, said in a statement.

A close-up of the backpack board and components before being folded and fitted to the dragonfly.
A close-up of the backpack board and components before being folded and fitted to the dragonfly.

Credit: Charles Stark Draper Laboratory

The project is a collaboration between the CSDL, which has been developing the backpack that controls the dragonfly, and the Howard Hughes Medical Institute (HHMI), where experts are identifying and enhancing “steering” neurons located in the dragonfly’s nerve cord, inserting genes that make it more responsive to light.

“This system pushes the boundaries of energy harvesting, motion sensing, algorithms, miniaturization and optogenetics, all in a system small enough for an insect to wear,” Wheeler said.

Even smaller than the dragonfly backpack are components created by CSDL called optrodes — optical fibers supple enough to wrap around the dragonfly’s nerve cord, so that engineers can target only the neurons related to flight, CSDL representatives explained in a statement.

And in addition to controlling insect flight, the tiny, flexible optrodes could have applications in human medicine, Wheeler added.

“Someday these same tools could advance medical treatments in humans, resulting in more effective therapies with fewer side effects,” Wheeler said. “Our flexible optrode technology provides a new solution to enable miniaturized diagnostics, safely access smaller neural targets and deliver higher precision therapies.”