Category Archives: Georgia Institute of Technology

Daydreaming is a sign you’re intelligent and creative

Daydreaming may indicate intelligence and creativity, according to new research.

“People with efficient brains may have too much brain capacity to stop their minds from wandering,” says Eric Schumacher, an associate psychology professor from Georgia Tech and coauthor of a new study.

“Our findings remind me of the absent-minded professor…”

Schumacher and his students and colleagues, including lead coauthor Christine Godwin, measured the brain patterns of more than 100 people while they lay in an MRI machine. The researchers instructed participants to focus on a stationary fixation point for five minutes. The team used the data to identify which parts of the brain worked in unison.

“The correlated brain regions gave us insight about which areas of the brain work together during an awake, resting state,” says Godwin, a Georgia Tech psychology PhD candidate.

“Interestingly, research has suggested that these same brain patterns measured during these states are related to different cognitive abilities.”

Once they figured out how the brain works together at rest, the team compared the data with tests the participants that measured their intellectual and creative ability. Participants also filled out a questionnaire about how much their mind wandered in daily life.

Those who reported more frequent daydreaming scored higher on intellectual and creative ability and had more efficient brain systems measured in the MRI machine.

“People tend to think of mind wandering as something that is bad. You try to pay attention and you can’t,” says Schumacher. “Our data are consistent with the idea that this isn’t always true. Some people have more efficient brains.”

Airline pilots admit their minds wander

Schumacher says higher efficiency means more capacity to think, and the brain may mind wander when performing easy tasks.

How can you tell if your brain is efficient? One clue is that you can zone in and out of conversations or tasks when appropriate, then naturally tune back in without missing important points or steps.

“Our findings remind me of the absent-minded professor—someone who’s brilliant, but off in his or her own world, sometimes oblivious to their own surroundings,” says Schumacher. “Or school children who are too intellectually advanced for their classes. While it may take five minutes for their friends to learn something new, they figure it out in a minute, then check out and start daydreaming.”

The researchers think their findings open the door for follow-up research to further understand when mind wandering is harmful, and when it may actually be helpful.

“There are important individual differences to consider as well, such as a person’s motivation or intent to stay focused on a particular task,” says Godwin.

Your brain should be a bit anxious and a bit ADHD

The researchers report their work in the journal Neuropsychologia.

The research is based on work supported by the Office of the Director of National Intelligence, Intelligence Advanced Research Projects Activity.

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation.

Source: Georgia Tech

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Flexible supercapacitor is made of paper

A new flexible, paper-based supercapacitor could power wearable electronics.

The device uses metallic nanoparticles to coat cellulose fibers in the paper, creating supercapacitor electrodes with high energy and power densities—and the best performance so far in a textile-based supercapacitor.

By implanting conductive and charge storage materials in the paper, the researchers’ layer-by-layer technique creates large surface areas that function as current collectors and nanoparticle reservoirs for the electrodes. Testing shows that devices fabricated with the technique can be folded thousands of times without affecting conductivity.

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The flexible metallized paper retains its conducting properties even when crumpled and folded. (Credit: Ko et al. via Nature Communications)

“This type of flexible energy storage device could provide unique opportunities for connectivity among wearable and internet of things devices,” says Seung Woo Lee, an assistant professor in the Woodruff School of Mechanical Engineering at the Georgia Institute of Technology. “We could support an evolution of the most advanced portable electronics. We also have an opportunity to combine this supercapacitor with energy-harvesting devices that could power biomedical sensors, consumer and military electronics, and similar applications.”

Energy storage devices are generally judged on three properties: their energy density, power density, and cycling stability. Supercapacitors often have high power density, but low energy density—the amount of energy that can be stored—compared to batteries, which often have the opposite attributes.

In developing their new technique, Lee and collaborators set out to boost energy density of the supercapacitors while maintaining their high power output.

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This image shows the difference between paper prior to metallization (left) and the paper coated with conductive nanoparticles. (Credit: Ko et al. via Nature Communications)

They began by dipping paper samples into a beaker of solution containing an amine surfactant material designed to bind the gold nanoparticles to the paper. Next, they dipped the paper into a solution containing gold nanoparticles. Because the fibers are porous, the surfactants and nanoparticles enter the fibers and become strongly attached, creating a conformal coating on each fiber.

By repeating the dipping steps, the researchers created a conductive paper on which they added alternating layers of metal oxide energy storage materials such as manganese oxide. The ligand-mediated layer-by-layer approach helped minimize the contact resistance between neighboring metal and/or metal oxide nanoparticles. Using the simple process done at room temperatures, researchers could build the layers up to provide the desired electrical properties.

“It’s basically a very simple process,” Lee says. “The layer-by-layer process, which we did in alternating beakers, provides a good conformal coating on the cellulose fibers. We can fold the resulting metallized paper and otherwise flex it without damage to the conductivity.”

Turning pine into graphene lets it carry electricity

Though the research involved small samples of paper, the solution-based technique could likely be scaled up using larger tanks or even a spray-on technique.

“There should be no limitation on the size of the samples that we could produce,” Lee says. “We just need to establish the optimal layer thickness that provides good conductivity while minimizing the use of the nanoparticles to optimize the tradeoff between cost and performance.”

The researchers demonstrated that their self-assembly technique improves several aspects of the paper supercapacitor, including its areal performance, an important factor for measuring flexible energy-storage electrodes. The maximum power and energy density of the metallic paper-based supercapacitors are estimated to be 15.1 mW/cm2 and 267.3 uW/cm2, respectively, substantially outperforming conventional paper or textile supercapacitors.

The next steps will include testing the technique on flexible fabrics and developing flexible batteries that could work with the supercapacitors. The researchers used gold nanoparticles because they are easy to work with, but plan to test less expensive metals such as silver and copper to reduce the cost.

During his PhD work, Lee developed the layer-by-layer self-assembly process for energy storage using different materials. With his collaborators, he saw a new opportunity to apply that to flexible and wearable devices with nanoparticles.

“We have nanoscale control over the coating applied to the paper,” he explains. “If we increase the number of layers, the performance continues to increase. And it’s all based on ordinary paper.”

Method could find ingredients for better batteries

The researchers report their work in the journal Nature Communications.

Additional researchers contributing to the work are from Korea University, the Photoelectronic Hybrids Research Center at the Korea Institute of Science and Technology, and Georgia Tech.

National Research Foundation (NRF) grants funded by the Korean government supported the research.

Source: Georgia Tech

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For emergency communication without power, use the ‘fog’

For natural disasters that knock out power—and therefore the internet—researchers have devised a new way of gathering and sharing information that doesn’t rely on electricity.

Using computing power built into mobile phones, routers, and other hardware, emergency managers and first responders will be able to share and act on information gathered from people affected by hurricanes, tornados, floods, and other disasters.

“Increasingly, data gathered from passive and active sensors that people carry with them, such as their mobile phones, is being used to inform situational awareness in a variety of settings,” says Kishore Ramachandran, a computer science professor at Georgia Tech.

“In this way, humans are providing beneficial social sensing services. However, current social sensing services depend on internet connectivity since the services are deployed on central cloud platforms.”

In a paper presented earlier this year at the 2nd International Workshop on Social Sensing, researchers detailed how it may be possible to access centralized services using a decentralized network that leverages the growing amount of computing power at the “edge” of the internet.

The ability will give first responders a huge advantage.

In a flooded area, for example, search and rescue personnel using a geo-distributed network would be able to continuously ping enabled phones, sensors, and other devices in an area to determine exact locations. The data is used to create density maps of people in that search region. The maps would then be used to prioritize and guide emergency response teams.

‘Fog’ or ‘edge’ computing

The proposal takes advantages of edge computing. Also known as fog computing, edge computing places more processing capabilities in sensing devices—like surveillance cameras, embedded pavement sensors, and others, as well as in consumer devices like cell phones, readers, and tablets—in order to improve network latency between sensors, apps, and users.

Rather than just being able to communicate through the internet with central cloud platforms, the researchers demonstrated that by harnessing edge computing resources, sensing devices can be enabled to identify and communicate with other sensors in an area.

‘Deep learning’ goes faster with organized data

“We believe fog computing can become a potent enabler of decentralized, local social sensing services that can operate when internet connectivity is constrained,” Ramachandran says.

“This capability will provide first responders and others with the level of situational awareness they need to make effective decisions in emergency situations.”

3 components

The team has proposed a generic software architecture for social sensing applications that is capable of exploiting the fog-enabled devices. The design has three components—a central management function that resides in the cloud, a data processing element placed in the fog infrastructure, and a sensing component on the user’s device.

It’s not enough to simply run a centralized social sensing service on a number of parallel fog nodes, the researchers say.

“Rather, the social sensing service has to become a distributed service capable of discovering available fog nodes and building a network that aggregates and shares information between social sensors that are connected to different fog nodes,” says computer science PhD student Harshit Gupta.

Beyond emergency response during natural disasters, the proposed fog architecture can also benefit communities with limited or no internet access. These include applications for public transportation management, job recruitment, and housing.

High-frequency chip makes fastest internet speeds look slow

Another possible application of the new approach is monitoring sensing devices in remote areas.

To monitor far-flung devices in areas with no internet access, a bus could be outfitted with fog-enabled sensing capabilities. As it travels in remote areas it would collect data from sensing devices. Once in range of internet connectivity, the “data mule” bus would upload the information to the centralized cloud-based platforms.

“In places that did not benefit from the first wave of cloud-based social sensing services, our hope is that these communities can leapfrog having to rely solely on the internet and directly use fog-based services,” Ramachandran says.

Source: Georgia Tech

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Try out your code on a swarm of real robots

Researchers from around the globe can write their own computer programs, upload them, then get the results as machines at Georgia Tech carry out the commands. The researchers will even send video evidence of the experiment.

This Robotarium opens this month. It’s a 725-square-foot facility that houses nearly 100 rolling and flying swarm robots.

The concept is easy, Magnus Egerstedt says: Robots for everyone.

“Building and maintaining a world-class, multi-robot lab is too expensive for a large number of current and budding roboticists. It creates a steep barrier for entry into our field,” says Egerstedt, a professor of electrical and computer engineering.

“Too many robot labs are hidden away behind closed doors.”

“We need to provide more access in order to continue creating the next generation of robots and robot-assisted technologies. The Robotarium will allow that at an unprecedented scale.”

In the facility, motion capture cameras cling from the ceiling and peer down at the lab’s centerpiece: a white, bowl-shaped arena that looks like a 12′ x 14′ hockey rink. That’s where up to 80 palm-sized, rolling robots scoot around the surface.

They automatically activate when given a program from someone in the room or a remote coder in a different state or country. Once it finishes the experiment, the swarm autonomously returns to wireless charging slots on the edge of the rink and waits to be activated for its next mission.

The lab is currently set up for the 3D-printed rolling machines. In a few weeks, autonomous quadcopters the size of small dinner plates will whiz through the air for remote flying experiments (a retractable net will keep them from slamming into walls or people if things unexpectedly get out of control). A large window allows curious onlookers to watch the organized chaos.

“The Robotarium is a terrarium for robots,” Egerstedt says. “We wanted to create a space where anyone, at any time of the day or night, can walk past the lab and see robots in action. Too many robot labs are hidden away behind closed doors.”

That’s exactly how Egerstedt’s team worked for the last year and a half. They experimented using a tabletop version of the Robotarium. The mini surface allowed them to iron out kinks and identify potential problems with open-access robotics. For instance, what if someone purposely uploaded code that would cause the bots to collide and demolish each other?

Toilet or chair? Robots that ‘see’ in 3D can tell

“That’s why we created algorithms that wrap a virtual barrier around each machine to prevent collisions,” says Siddharth Mayya, a PhD student in the lab. “We also had to worry about hackers.”

“I want to do for robotics what MOOCs have done for education—now anyone who knows how to code can work with robots.”

Part of the work included developing processes to protect the system from cyber threats.

Not everything always went smoothly. When PhD student Li Wang hit a button that sent his swarm of quadcopters shooting toward the ceiling, “It rained robots that day,” he recalls.

Another time, a rolling swarm descended on the same charging station at the same time. The robots literally fought for a spot until they reached the metal rail, which shorted them out and sprayed sparks across the room.

That’s why the Robotarium’s charging stations are now wireless.

To date, more than 100 research groups have logged on and used the mini-version.

Most are roboticists without access to swarm technology. Others are biologists. One team chose to use robots, instead of computer simulations, to better understand how ants interact with each other when choosing a new queen.

Telescoping design would make awesome robots

Egerstedt thinks the new facility will foster more collaboration within the robotics community, allowing scientists and engineers to share their findings more widely and build on successes. The open access setting will counter the lack of resources that sometime stands in the way of research.

“I want to do for robotics what MOOCs (massive open online courses) have done for education—now anyone who knows how to code can work with robots,” he says.

He already has a new recruit. This past April, a group of fifth graders stopped in for a tour. Egerstedt saw one of the 10-year-olds stuffing one of the robots into his pocket while turning to leave.

“I asked him why he took it,” Egerstedt remembers. “He said he wanted to make it better.”

How?

“By adding a flamethrower.”

The National Science Foundation and Office of Naval Research funded the lab.

Source: Georgia Tech

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3 ways to know if a 3D printer got hacked

Researchers have developed three new methods to detect cyberattacks on 3D printers.

“They will be attractive targets because 3D-printed objects and parts are used in critical infrastructures around the world, and cyberattacks may cause failures in health care, transportation, robotics, aviation, and space,” says Saman Aliari Zonouz, an associate professor in the electrical and computer engineering department at Rutgers University-New Brunswick.

3D printer cyberattack process chart
Engineers have devised three ways to combat cyberattacks on 3D printers: monitoring printer motion and sounds and using tiny gold nanoparticles. (Credit: Christian Bayens/Georgia Tech/Rutgers)

Zonouz coauthored the study describing the methods for protecting 3D printers from hackers, which was published at the 26th USENIX Security Symposium in Vancouver, Canada.

“Imagine outsourcing the manufacturing of an object to a 3D printing facility and you have no access to their printers and no way of verifying whether small defects, invisible to the naked eye, have been inserted into your object,” says Mehdi Javanmard, study coauthor and assistant professor in the electrical and computer engineering department at the university.

“The results could be devastating and you would have no way of tracing where the problem came from,” he says.

“You’ll see more types of attacks as well as proposed defenses in the 3D printing industry within about five years…”

3D printing, also called additive manufacturing, plays an increasingly important role in industrial manufacturing. But health- and safety-related products such as medical prostheses and aerospace and auto parts are being printed with no standard way to verify them for accuracy, the study says. Even houses and buildings are being manufactured by 3D printers, notes Javanmard.

Proving hacks are possible

Instead of spending up to $100,000 or more to buy a 3D printer, many companies and organizations send software-designed products to outside facilities for printing, Zonouz says. But the firmware in printers may be hacked.

For their study, the researchers bought several 3D printers and showed that it’s possible to hack into a computer’s firmware and print defective objects. The defects were undetectable on the outside but the objects had holes or fractures inside them.

Other researchers have shown in a YouTube video how hacking can lead to a defective propeller in a drone, causing it to crash, Zonouz notes.

While anti-hacking software is essential, it’s never 100 percent safe against cyberattacks. So the researchers looked at the physical aspects of 3D printers.

3D printing helps predict if new heart valves will leak

3 ways to keep 3D printing secure

The three methods researchers have developed to detect hacking attacks on 3D printers include:

  • Acoustic measurement of the 3D printer in operation. When compared to a reference recording of a correct print, this acoustic monitoring—done with an inexpensive microphone and filtering software—can detect changes in the printer’s sound that may indicate installation of malicious software.
  • Physical tracking of printer components. To create the desired object, the printer’s extruder and other components should follow a consistent mechanical path that can be observed with inexpensive sensors. Variations from the expected path could indicate an attack.
  • Detection of nanorods in finished components. Using Raman Spectroscopy and computed tomography (CT), the researchers were able to detect the location of gold nanorods that had been mixed with the filament material used in the 3D printer. Variations from the expected location of those particles could indicate a quality problem with the component. The variations could result from malicious activity, or from efforts to conserve printer materials.

In 3D printing, the software controls the printer, which fulfills the virtual design of an object. The physical part includes an extruder or “arm” through which filament (plastic, metal wire, or other material) is pushed to form an object.

The researchers observed the motion of the extruder, using sensors, and monitored sounds made by the printer via microphones.

“Just looking at the noise and the extruder’s motion, we can figure out if the print process is following the design or a malicious defect is being introduced,” Zonouz says.

The third method they developed involves examining an object to see if it was printed correctly. Tiny gold nanoparticles, acting as contrast agents, are injected into the filament and sent with the 3D print design to the printing facility. Once the object is printed and shipped back, high-tech scanning reveals whether the nanoparticles—a few microns in diameter—have shifted in the object or have holes or other defects.

“This idea is kind of similar to the way contrast agents or dyes are used for more accurate imaging of tumors as we see in MRIs or CT scans,” Javanmard says.

The next steps in their research include investigating other possible ways to attack 3D printers, proposing defenses, and transferring methods to industry, Zonouz says.

Among the challenges ahead will be obtaining good acoustic data in the noisy environments in which 3D printers typically operate. In the research, operation of other 3D printers near the one being observed cut the accuracy significantly, but Raheem Beyah, a professor and associate chair in Georgia Tech’s School of Electrical and Computer Engineering, believes that challenge can be addressed with additional signal processing.

“These 3D printed components will be going into people, aircraft, and critical infrastructure systems,” says Beyah. “Malicious software installed in the printer or control computer could compromise the production process. We need to make sure that these components are produced to specification and not affected by malicious actors or unscrupulous producers.”

Ink designed to 3D print bone implants for kids

“You’ll see more types of attacks as well as proposed defenses in the 3D printing industry within about five years,” Zonouz says.

Additional coauthors of this study are from the Georgia Institute of Technology and Rutgers University.

Source: Rutgers University, Georgia Tech

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Spring-loaded stairs spare knees and ankles

Researchers have built energy-recycling stairs that store a user’s energy during descent and return energy to the user during ascent, making the trip up easier.

The spring-loaded stairs compress when someone comes down the stairs, saving energy otherwise dissipated through impact and braking forces at the ankle by 26 percent. When going up, the stairs give people a boost by releasing the stored energy, making it 37 percent easier on the knee than using conventional stairs. The low-power device can be placed on existing staircases and doesn’t have to be permanent.

Each stair is tethered by springs and equipped with pressure sensors. When a person walks downstairs, each step slowly sinks until it locks into place and is level with the next step, storing energy generated by the user. It stays that way until someone walks upstairs. When a person ascending the stairs steps on the sensor on the next tread up, the latch on the lower step releases. The stored energy in the spring is also released, lifting up the back leg.

The paper appears in the journal PLOS ONE. The authors say the initial idea was to use energy-recycling prosthetic shoes to help people going up stairs.

“Unlike normal walking where each heel-strike dissipates energy that can be potentially restored, stair ascent is actually very energy efficient; most energy you put in goes into potential energy to lift you up,” says Karen Liu, an associate professor in Georgia Tech’s School of Interactive Computing. “But then I realized that going downstairs is quite wasteful. You dissipate energy to stop yourself from falling, and I thought it would be great if we could store the energy wasted during descent and return it to the user during ascent.”

Liu is a coauthor of the paper with colleague Lena Ting, a professor of biomedical engineering in the Wallace H. Coulter Department of Biomedical Engineering at Emory and Georgia Tech.

“Walking down stairs is like tapping the breaks of your car while revving the engine,” says Ting. “Your legs use a lot of energy bracing each step to avoid falling too fast. Our stairs store that energy rather than wasting it.”

The temporary stairs could also be helpful for those recovering from surgery or pregnant women.

The researchers didn’t expect, prior to designing the device, that the stairs would actually ease the impact of going downstairs.

“The spring in the stairs, instead of the ankle, acts as a cushion and brake,” says Yun Seong Song, who built the device as a postdoctoral researcher at Georgia Tech. He’s currently an assistant professor at Missouri University of Science and Technology. “The gentle downward movement alleviates work by the trailing ankle, which is what keeps you balanced and prevents you from falling too fast on normal stairs.”

Liu initially got the idea for the project when she attended a conference and saw an ankle brace that stored and released energy. Her 72-year-old mother has no problems walking but has difficulty climbing steps, and Liu knew she wouldn’t wear special sneakers just for stairs. So she decided to make smart stairs that act like the shoe.

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“Current solutions for people who need help aren’t very affordable. Elevators and stair-lifts are often impractical to install at home,” Liu says. “Low-cost, easily installed assistive stairs could be a way to allow people to retain their ability to use stairs and not move out of their homes.”

“Maintaining mobility is very much a use-it-or-lose-it thing. It’s important to keep people walking and independent through injury and aging to maximize quality of life,” said Ting.

The researchers think the temporary stairs could also be helpful for those recovering from surgery or pregnant women—people who only need help for short periods of time and don’t need to permanently alter their homes.

The researchers are looking for partners to extend the project, which currently runs on a staircase with only two steps and can be used by just one person at a time.

Any opinions, findings and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation, which funded the work.

Source: Georgia Tech

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Watch: Fire ants climb each other to build moving tower

Fire ants use their bodies to build tower-like structures —all without a plan, a leader, or coordinated effort, new research suggests.

Each ant, researchers say, wanders around aimlessly, adhering to a certain set of rules, until it unknowingly participates in the construction of a tower several inches tall.

“If you watched ants for 30 seconds, you could have no idea that something miraculous would be created in 20 minutes,” says coauthor David Hu, a professor in the Georgia Institute of Technology’s George W. Woodruff School of Mechanical Engineering. “With no planning, and using trial-and-error, they create a bell-shaped structure that helps them survive.”

The tower study is a follow-up to the group’s 2014 ant raft research, which examined how the insects link their bodies in order to build waterproof structures that stay afloat for months. The ants march along until they come to an open space—the edge of the raft—then settle in to become a building block of the raft.

They do the same thing for the towers, searching for an empty spot like a car in a crowded parking lot. Once an individual ant finds one, typically at the top of the tower, she stops and braces for more ants to climb on top and go vertical.

They build these towers when they run into a tall obstruction while looking for food or escaping to new areas.

two ant towers and Eiffel tower
The weight of towers, both in France and made by ants, is supported by a wider cross-section at the base. This allows an equal distribution of the weight. (Credit: Georgia Tech)

But vertical is a relative term. The ants don’t position themselves straight up and down like a skyscraper. Instead, the tower gets wider as it grows taller, gradually becoming the same shape as Paris’ iconic landmark. The weight of the tower is supported by a wider cross-section at its base, which allows the ants to better distribute their weight.

“The tower is constantly rebuilding and replacing its surface.”

“We found that ants can withstand 750 times their body weight without injury, but they seem to be most comfortable supporting three ants on their backs,” says Craig Tovey, a coauthor of the study and professor in the Stewart School of Industrial & Systems Engineering. “Any more than three and they’ll simply give up, break their holds, and walk away.”

Even though the ants evenly distribute their weight as a group, the tower is in constant motion. The column sinks as the insects work, as if the bottom is being melted like butter. The ants slide down, then exit out of tunnels buried in the base. The tower’s movement is similar to a slow-motion chocolate fountain in reverse.

The sinking towers were discovered by accident. The researchers planned to record ants building for two hours, but the camera rolled for three.

“We didn’t expect to see anything interesting in that extra hour, so we sped up the video to 10 times real speed,” says Tovey. “We were amazed at how different the ant movements appeared.”

Ants wear smells like a uniform

In real time, they saw ants busily moving on the surface of a tower of apparently stationary ants. At high speed, however, the surface ant movements appeared as a blur and the entire tower slipped downward.

“The tower sinking was too slow to see at real speed,” says Tovey.

The sinking was confirmed by X-ray videography. The researchers fed some of the ants radioactive food, then threw the colony in an X-ray machine across campus in Dan Goldman’s physics lab. Cameras again recorded the critters building a tower. Using time-lapse photography, they watched the radioactive insects walk up the sides, gradually sink to the tower’s depths, leave the pile, then continually repeat the process for hours.

“Ant towers are like human skin,” says Hu, who is also a faculty member in the School of Biological Sciences. “The tower is constantly rebuilding and replacing its surface.”

The findings could have implications for modular robots, which currently aren’t very effective at building tall towers.

Tovey, who is also a biologist, has a different reason for studying ant behavior.

Teeming ants act like both a liquid and a solid

“Ninety-nine percent of all the species that have ever lived on Earth are extinct,” Tovey says. “The rest of us have developed very effective techniques to survive. Why wouldn’t we study these processes? Engineers and scientists don’t always know what our findings will lead to, but bioinspired design can be a powerful tool to make our world more efficient.”

The paper appears in the journal Royal Society Open Science.

Source: Georgia Institute of Technology

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3D printing helps predict if new heart valves will leak

Heart valve models created with advanced 3D printers could soon help cardiologists prepare to perform life-saving heart valve replacements.

Researchers are using standard medical imaging and new 3D-printing technologies to create patient-specific heart valve models that mimic the physiological qualities of the real valves. Their aim is to improve the success rate of transcatheter aortic valve replacements (TAVR) by picking the right prosthetic and avoiding a common complication known as paravalvular leakage.

“Paravalvular leakage is an extremely important indicator in how well the patient will do long term with their new valve,” says Zhen Qian, chief of cardiovascular imaging research at Piedmont Heart Institute, which is part of Piedmont Healthcare. “The idea was, now that we can make a patient-specific model with this tissue-mimicking 3D-printing technology, we can test how the prosthetic valves interact with the 3D-printed models to learn whether we can predict leakage.”

Inside the 3D-printed model of a human heart valve, black regions represent the location of actual calcium deposits.
Inside the 3D-printed model of a human heart valve, black regions represent the location of actual calcium deposits. (Credit: Rob Felt/Georgia Tech)

The researchers, whose study appears in JACC: Cardiovascular Imaging, find that the models, created from CT scans of the patients’ hearts, behaved so similarly to the real ones that they could reliably predict the leakage.

“These 3D-printed valves have the potential to make a huge impact on patient care going forward,” says Chuck Zhang, a professor in the Stewart School of Industrial and Systems Engineering at Georgia Tech.

Tens of thousands of patients each year are diagnosed with heart valve disease, and TAVR is often considered for patients who are at high risk for complications with an open-heart surgery to replace the valve.

The prosthetic valves are made in a variety of sizes from multiple manufacturers. Leakage occurs when the new valve doesn’t achieve a precise fit and blood flows around the prosthetic rather than through it as intended. Reducing the chances for leakage is key to patient outcome for the procedure.

“In preparing to conduct a valve replacement, interventional cardiologists already weigh a variety of clinical risk predictors, but our 3D-printed model gives us a quantitative method to evaluate how well a prosthetic valve fits the patient,” Qian says.

Can algae and light treat heart disease?

Researchers create the models with a special metamaterial design and a multi-material 3D printer, which gives them control over such design parameters as diameter and curving wavelength of the metamaterial used for printing, to more closely mimic physiological properties of the tissue.

For example, the models can recreate conditions such as calcium deposition—a common underlying factor of aortic stenosis—as well as arterial wall stiffness and other unique aspects of a patient’s heart.

“Previous methods of using 3D printers and a single material to create human organ models were limited to the physiological properties of the material used,” Zhang says. “Our method of creating these models using metamaterial design and multi-material 3D printing takes into account the mechanical behavior of the heart valves, mimicking the natural strain-stiffening behavior of soft tissues that comes from the interaction between elastin and collagen, two proteins found in heart valves.”

Embedding wavy, stiff microstructures into the softer material during the 3D printing process simulated that interaction.

‘Bulge index’

The researchers created heart valve models from medical imaging of 18 patients who had undergone a valve replacement surgery. The models were outfitted with dozens of radiopaque beads to help measure the displacement of the tissue-mimicking material.

The researchers then paired those models with the same type and size prosthetic valves that interventional cardiologists had used during each patient’s valve replacement procedure. Inside a warm-water testing environment controlled to maintain human body temperature, the researchers implanted the prosthetics inside the models, being careful to place the new valves in the exact location that was used during the clinical procedure for each case.

This existing drug could keep heart valves bendy

Software analyzed medical imaging showing the location of the radiopaque beads taken before and after the experiment to determine how the prosthetics interacted with the 3D-printed models, looking for inconsistencies representing areas where the prosthetic wasn’t sealed well against the wall of the valve.

Those inconsistencies were assigned values that formed a “bulge index,” and the researchers found that a higher bulge index was associated with patients who had experienced a higher degree of leakage after valve placement. In addition to predicting the occurrence of the leakage, the 3D-printed models were also able to replicate the location and severity of the complication during the experiments.

“The results of this study are quite encouraging,” Qian says. “Even though this valve replacement procedure is quite mature, there are still cases where picking a different size prosthetic or different manufacturer could improve the outcome, and 3D printing will be very helpful to determine which one.”

Matching patients and valves

While the researchers found that another variable—how much calcium had accumulated on the patient’s natural valve—could also predict with high accuracy whether there would be a higher degree of leakage, results from their tests showed that the new method using 3D-printed valves was a better predictor in certain cases where balloons are used during the procedure to expand the prosthetic valve for a better fit.

The researchers plan to continue to optimize the metamaterial design and 3D printing process and evaluate the use of the 3D-printed valves as a pre-surgery planning tool, testing a larger number of patient-specific models, and looking for ways to further refine their analytic tools.

“Eventually, once a patient has a CT scan, we could create a model, try different kinds of valves in there, and tell the physician which one might work best,” Qian says. “We could even predict that a patient would probably have moderate paravalvular leakage, but a balloon dilatation will solve it.”

Source: Georgia Tech

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To stop cancer’s spread, break its ‘legs’

Cancer cells most often kill by crawling away from their original tumors to later re-root in vital parts of the body in a process called metastasis.

Bristly leg-like protrusions that cover cancer cells enable them to creep. When researchers gently heated minuscule gold rods with a laser in experiments on common laboratory cultures (in vitro) of cancerous human cells, they were able to mangle the protrusions and prevent cell migration, a key mechanism in metastasis.

In the future, the technique could potentially offer clinicians going after individual tumors a weapon to combat cancer’s spread at the same time.

“If cancer stays in a tumor in one place, you can get to it, and it’s not so likely to kill the patient, but when it spreads around the body, that’s what really makes it deadly,” says lead researcher Mostafa El-Sayed, professor of chemistry and biochemistry at Georgia Institute of Technology and lead researcher of the study in the Proceedings of the National Academy of Sciences.

Squished cancer cells break free from the crowd

The treatment can also easily kill cancer cells, but in this experiment, it was vital to specifically show that it greatly slowed cell migration.

The experimental treatment also spares healthy cells, in these and in prior experiments, making it potentially much less taxing on patients than commonly used chemotherapy. In past tests in animal models, there were no toxic side effects from the gold used in the treatment, and no observable damage to healthy tissue from the low-energy laser. And there was no recurrence of the treated cancer.

“The method appears to be very effective as a locally administered treatment that also protects the body from cancers spread away from the treated tumors, and it is also very mild, so it can be applied many times over if needed,” El-Sayed says.

How it works

A close-up look at a cell and what malignant cancer can do to it clarifies how the treatment works, researchers say.

Many people think of cells as watery balloons—fluid encased in a membrane sheath with organelles floating around inside. But that picture is incomplete. Cells have support grids called cytoskeletons that give them form and that have functions.

The cytoskeletons also form bristly protrusions called filopodia, which extend out from a weave of fibers called lamellipodia on the cells fringes. The protrusions normally help healthy cells shift their location in the tissue that they are part of.

But in malignant cancer, normally healthy cell functions often lunge into destructive overdrive. Lamellipodia and filopodia are wildly overproduced.

“All these lamellipodia and filopodia give the cancer cells legs,” says Yue Wu, a graduate student in bioanalytical chemistry. “The metastasis requires those protrusions, so the cells can travel.”

Bubble pushes 1 cancer cell from device at a time

The gold nanorods thwart the protrusions in two ways. The rods are comprised of a small collection of gold atoms—nano refers to something being just billionths of meters (or feet) in size.

First, El-Sayed’s nanorods are introduced locally, where they encumber the leggy protrusions on cancerous cells. The rods are coated with molecules (RGD-peptides) that make them stick specifically to a type of cell protein called integrin.

“The targeted nanorods tied up the integrin and blocked its functions, so it could not keep guiding the cytoskeleton to overproduce lamellipodia and filopodia,” says Yan Tang, a postdoctoral assistant in computational biology. The binding of the integrin alone slowed down the migration of malignant cells.

But healthy cells stayed safe. “There are certain, specific integrins that are overproduced in cancerous cells,” says Moustafa Ali, one of the study’s first authors. “And you don’t find them so much in healthy cells.”

Gentle laser

In the second phase, researchers hit the gold nanoparticles with a low-energy laser of near-infrared (NIR) light. It brought the migration of the cancer cells to an observable halt.

“The light was not absorbed by the cells, but the gold nanorods absorbed it, and as a result, they heated up and partially melted cancer cells they are connected with, mangling lamellipodia and filopodia,” Ali says. “It didn’t kill all the cells, not in this experiment. If we killed them, we would not have been able to observe whether we stopped them from migrating or not.” But if necessary, the treatment can be adjusted to kill the cells.

Early experiments in animal models in vivo with hotter lasers didn’t work as well.  “That caused inflammation, which made it possible to heat one time only,” Ali says. “As a result, that high temperature would wipe out many cancer cells, but not all of them. Some hidden ones might have survived, and also still been able to migrate.”

“This gentle laser didn’t burn the skin or damage tissue, so it could be dosed multiple times and more thoroughly stop the cancer cells from being able to travel,” says researcher Ronghu Wu.

How some breast cancer cells return after chemo

Researchers envision treating head, neck, breast, and skin cancers with direct, local nanorod injections combined with the low-power near-infrared laser, which can hit the gold nanorods 2-3 centimeters (around an inch) deep inside tissue. “But it could go as deep as 4-5 centimeters,” Ali says.

Deeper tumors could conceivably be treated with deeper injections of nanorods. “Then you’d need to go in with a fiber optic or endoscopic laser,” El-Sayed says. Injecting the nanorods directly into the bloodstream as a broad treatment is not currently a viable option.

El-Sayeds group has previously published in vivo experiments in mice in the Proceedings of the National Academy of Sciences together with Emory University School of Medicine. That study showed no observable toxicity from the gold in mice 15 months after treatment.

“A lot of it ended up in the liver and spleen,” El-Sayed says. “But the functions of these organs appeared intact upon examination, and treated mice were alive and healthy over a year later.”

Other coauthors are from Georgia Tech and Georgia State University. The National Science Foundation Division of Chemistry and the National Institutes of Health funded the work.

Source: Georgia Tech

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Painless patch works just as well as flu shot

A phase I clinical trial finds that influenza vaccination using Band-Aid-like patches with dissolvable microneedles is safe and well-tolerated by study participants.

In addition, the patches are as effective in generating immunity against influenza, and study participants strongly preferred them over vaccination with a hypodermic needle and syringe.

Despite the potentially severe consequences of illness and even death, only about 40 percent of adults in the United States receive flu shots each year. A new self-administered, painless vaccine skin patch containing microscopic needles may offer a solution.

Experts say the microneedle patch vaccine could also save money because it is easily self-administered, can be transported and stored without refrigeration, and is easily disposed of after use without sharps waste.

“Having the option of a flu vaccine that can be easily and painlessly self-administered could increase coverage and protection by this important vaccine.”

“Despite the recommendation of universal flu vaccination, influenza continues to be a major cause of illness leading to significant morbidity and mortality,” says first author Nadine Rouphael, associate professor of medicine (infectious diseases) at Emory University School of Medicine and principal investigator of the clinical trial.

“Having the option of a flu vaccine that can be easily and painlessly self-administered could increase coverage and protection by this important vaccine.”

The first-in-human clinical trial of the flu vaccine patches began in June 2015 with 100 participants aged 18-49 who were healthy and who had not received the influenza vaccine during the 2014-15 flu season. The study was conducted at the Hope Clinic of the Emory Vaccine Center in Atlanta and was carried out under an Investigational New Drug Application authorized by the FDA.

How to make flu vaccine spray safe for little noses

Participants were randomized into four groups: (1) vaccination with microneedle patch given by a health care provider; (2) vaccination with microneedle patch self-administered by study participants; (3) vaccination with intramuscular injection given by a health care provider; and (4) placebo microneedle patch given by a health care provider.

“People have a lot of reasons for not getting flu vaccinations,” says senior coauthor Mark Prausnitz, professor of chemical and biomolecular engineering at Georgia Institute of Technology.

“One of the main goals of developing the microneedle patch technology was to make vaccines accessible to more people. Traditionally, if you get an influenza vaccine you need to visit a health care professional who will administer the vaccine using a hypodermic needle.

“The vaccine is stored in the refrigerator, and the used needle must be disposed of in a safe manner. With the microneedle patch, you could pick it up at the store and take it home, put it on your skin for a few minutes, peel it off and dispose of it safely, because the microneedles have dissolved away. The patches can also be stored outside the refrigerator, so you could even mail them to people.”

Vaccination with the microneedle patches was safe, with no adverse events reported. Local skin reactions to the patches were mostly faint redness and mild itching that lasted two to three days. No new chronic medical illnesses or influenza-like illnesses were reported with either the patch or the injection groups.

Will this microneedle patch help wipe out measles?

Antibody responses generated by the vaccine, as measured through analysis of blood samples, were similar in the groups vaccinated using patches and those receiving intramuscular injection, and these immune responses were still present after six months. More than 70 percent of patch recipients reported they would prefer patch vaccination over injection or intranasal vaccination for future vaccinations.

No significant difference was seen between the doses of vaccine delivered by the health care workers and the volunteers who self-administered the patches, showing that participants were able to correctly self-administer the patch. After vaccination, imaging of the used patches found that the microneedles had dissolved in the skin, suggesting that the used patches could be safely discarded as non-sharps waste. The vaccines remained potent in the patches without refrigeration for at least one year.

The microneedle patches used in the study were designed at Georgia Tech and manufactured by the Global Center for Medical Innovation in Atlanta.

Researchers also are working to develop microneedle patches for use with other vaccines, including measles, rubella, and polio.

“Influenza vaccination using microneedle patches is well-tolerated, well-accepted, and results in robust immunologic responses, whether administered by health care workers or by the participants themselves. These results provide evidence that microneedle patch vaccination is an innovative new approach with the potential to improve current vaccination coverage and reduce immunization costs,” the authors write in The Lancet.

The National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health funded the work.

Source: Georgia Tech

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