Printing 3D Blood Vessel Networks out of Sugar

Engineerblogger
Aug 3, 2012

3D Printing Blood Vessel Networks

Scientists can already grow thin layers of cells, so one proposed solution to the vasculature problem is to “print” the cells layer by layer, leaving openings for blood vessels as necessary. But this method leaves seams, and when blood is pumped through the vessels, it pushes those seams apart.

Bioengineers from the University of Pennsylvania have turned the problem inside out by using a 3D printer called a RepRap to make templates of blood vessel networks out of sugar. Once the networks are encased in a block of cells, the sugar can be dissolved, leaving a functional vascular network behind.

“I got the first hint of this solution when I visited a Body Worlds exhibit, where you can see plastic casts of free-standing, whole organ vasculature,” says Bioengineering postdoc Jordan Miller.

Miller, along with Christopher Chen, the Skirkanich Professor of Innovation in the Department of Bioengineering, other members of Chen’s lab, and colleagues from MIT, set out to show that this method of developing sugar vascular networks helps keep interior cells alive and functioning.

After the researchers design the network architecture on a computer, they feed the design to the RepRap. The printer begins building the walls of a stabilizing mold. Then it then draws filaments across the mold, pulling the sugar at different speeds to achieve the desired thickness of what will become the blood vessels.

After the sugar has hardened, the researchers add liver cells suspended in a gel to the mold. The gel surrounds the filaments, encasing the blood vessel template. After the gel sets it can be removed from the mold with the template still inside. The block of gel is then washed in water, dissolving the remaining sugar inside. The liquid sugar flows out of the vessels it has created without harming the growing cells.

“This new technology, from the cell’s perspective, makes tissue formation a gentle and quick journey,” says Chen.

The researchers have successfully pumped nutrient-rich media, and even blood, through these gels blocks’ vascular systems. They also have experimentally shown that more of the liver cells survive and produce more metabolites in gels that have these networks.

The RepRap makes testing new vascular architectures quick and inexpensive, and the sugar is stable enough to ship the finished networks to labs that don’t have 3D printers of their own. The researchers hope to eventually use this method to make implantable organs for animal studies.

Source: 

University of Pennsylvania

Engineers develop an ‘intelligent co-pilot’ for cars

Engineerblogger
July 19, 2012







Barrels and cones dot an open field in Saline, Mich., forming an obstacle course for a modified vehicle. A driver remotely steers the vehicle through the course from a nearby location as a researcher looks on. Occasionally, the researcher instructs the driver to keep the wheel straight — a trajectory that appears to put the vehicle on a collision course with a barrel. Despite the driver’s actions, the vehicle steers itself around the obstacle, transitioning control back to the driver once the danger has passed.

The key to the maneuver is a new semiautonomous safety system developed by Sterling Anderson, a PhD student in MIT’s Department of Mechanical Engineering, and Karl Iagnemma, a principal research scientist in MIT’s Robotic Mobility Group.

The system uses an onboard camera and laser rangefinder to identify hazards in a vehicle’s environment. The team devised an algorithm to analyze the data and identify safe zones — avoiding, for example, barrels in a field, or other cars on a roadway. The system allows a driver to control the vehicle, only taking the wheel when the driver is about to exit a safe zone.

Anderson, who has been testing the system in Michigan since last September, describes it as an “intelligent co-pilot” that monitors a driver’s performance and makes behind-the-scenes adjustments to keep the vehicle from colliding with obstacles, or within a safe region of the environment, such as a lane or open area.

“The real innovation is enabling the car to share [control] with you,” Anderson says. “If you want to drive, it’ll just … make sure you don’t hit anything.”

The group presented details of the safety system recently at the Intelligent Vehicles Symposium in Spain.

Off the beaten path

Robotics research has focused in recent years on developing systems — from cars to medical equipment to industrial machinery — that can be controlled by either robots or humans. For the most part, such systems operate along preprogrammed paths.

As an example, Anderson points to the technology behind self-parking cars. To parallel park, a driver engages the technology by flipping a switch and taking his hands off the wheel. The car then parks itself, following a preplanned path based on the distance between neighboring cars.

While a planned path may work well in a parking situation, Anderson says when it comes to driving, one or even multiple paths is far too limiting.

“The problem is, humans don’t think that way,” Anderson says. “When you and I drive, [we don’t] choose just one path and obsessively follow it. Typically you and I see a lane or a parking lot, and we say, ‘Here is the field of safe travel, here’s the entire region of the roadway I can use, and I’m not going to worry about remaining on a specific line, as long as I’m safely on the roadway and I avoid collisions.’”

Anderson and Iagnemma integrated this human perspective into their robotic system. The team came up with an approach to identify safe zones, or “homotopies,” rather than specific paths of travel. Instead of mapping out individual paths along a roadway, the researchers divided a vehicle’s environment into triangles, with certain triangle edges representing an obstacle or a lane’s boundary.

The researchers devised an algorithm that “constrains” obstacle-abutting edges, allowing a driver to navigate across any triangle edge except those that are constrained. If a driver is in danger of crossing a constrained edge — for instance, if he’s fallen asleep at the wheel and is about to run into a barrier or obstacle — the system takes over, steering the car back into the safe zone.

Building trust

So far, the team has run more than 1,200 trials of the system, with few collisions; most of these occurred when glitches in the vehicle’s camera failed to identify an obstacle. For the most part, the system has successfully helped drivers avoid collisions.

Benjamin Saltsman, manager of intelligent truck vehicle technology and innovation at Eaton Corp., says the system has several advantages over fully autonomous variants such as the self-driving cars developed by Google and Ford. Such systems, he says, are loaded with expensive sensors, and require vast amounts of computation to plan out safe routes.

"The implications of [Anderson's] system is it makes it lighter in terms of sensors and computational requirements than what a fully autonomous vehicle would require," says Saltsman, who was not involved in the research. "This simplification makes it a lot less costly, and closer in terms of potential implementation."

In experiments, Anderson has also observed an interesting human response: Those who trust the system tend to perform better than those who don’t. For instance, when asked to hold the wheel straight, even in the face of a possible collision, drivers who trusted the system drove through the course more quickly and confidently than those who were wary of the system.

And what would the system feel like for someone who is unaware that it’s activated? “You would likely just think you’re a talented driver,” Anderson says. “You’d say, ‘Hey, I pulled this off,’ and you wouldn’t know that the car is changing things behind the scenes to make sure the vehicle remains safe, even if your inputs are not.”

He acknowledges that this isn’t necessarily a good thing, particularly for people just learning to drive; beginners may end up thinking they are better drivers than they actually are. Without negative feedback, these drivers can actually become less skilled and more dependent on assistance over time. On the other hand, Anderson says expert drivers may feel hemmed in by the safety system. He and Iagnemma are now exploring ways to tailor the system to various levels of driving experience.

The team is also hoping to pare down the system to identify obstacles using a single cellphone. “You could stick your cellphone on the dashboard, and it would use the camera, accelerometers and gyro to provide the feedback needed by the system,” Anderson says. “I think we’ll find better ways of doing it that will be simpler, cheaper and allow more users access to the technology.”

This research was supported by the United States Army Research Office and the Defense Advanced Research Projects Agency. The experimental platform was developed in collaboration with Quantum Signal LLC with assistance from James Walker, Steven Peters and Sisir Karumanchi.

Source: MIT News

Autonomous robot scans ship hulls for mines

MIT News
July 17, 2012

Algorithms developed by MIT researchers enable an autonomous underwater vehicle (AUV) to swim around and reconstruct a ship's propeller. 

Image: Franz Hover, Brendan Englo

For years, the U.S. Navy has employed human divers, equipped with sonar cameras, to search for underwater mines attached to ship hulls. The Navy has also trained dolphins and sea lions to search for bombs on and around vessels. While animals can cover a large area in a short amount of time, they are costly to train and care for, and don’t always perform as expected.

In the last few years, Navy scientists, along with research institutions around the world, have been engineering resilient robots for minesweeping and other risky underwater missions. The ultimate goal is to design completely autonomous robots that can navigate and map cloudy underwater environments — without any prior knowledge of those environments — and detect mines as small as an iPod.

Now Franz Hover, the Finmeccanica Career Development Associate Professor in the Department of Mechanical Engineering, and graduate student Brendan Englot have designed algorithms that vastly improve such robots’ navigation and feature-detecting capabilities. Using the group’s algorithms, the robot is able to swim around a ship’s hull and view complex structures such as propellers and shafts. The goal is to achieve a resolution fine enough to detect a 10-centimeter mine attached to the side of a ship.

“A mine this small may not sink the vessel or cause loss of life, but if it bends the shaft, or damages the bearing, you still have a big problem,” Hover says. “The ability to ensure that the bottom of the boat doesn’t have a mine attached to it is really critical to vessel security today.”

Hover and his colleagues have detailed their approach in a paper to appear in theInternational Journal of Robotics Research.

To read more click here...

Why platinum is the wrong material for fuel cell?

Engineerblogger
July 19, 2012

Professor Alfred Anderson

Fuel cells are inefficient because the catalyst most commonly used to convert chemical energy to electricity is made of the wrong material, a researcher at Case Western Reserve University argues. Rather than continue the futile effort to tweak that material—platinum—to make it work better, Chemistry Professor Alfred Anderson urges his colleagues to start anew.

“Using platinum is like putting a resistor in the system,” he said. Anderson freely acknowledges he doesn’t know what the right material is, but he’s confident researchers’ energy would be better spent seeking it out than persisting with platinum.

“If we can find a catalyst that will do this [more efficiently],” he said, “it would reach closer to the limiting potential and get more energy out of the fuel cell.”

Anderson’s analysis and a guide for a better catalyst have been published in a recent issue of Physical Chemistry Chemical Physics and in Electrocatalysis online.

Even in the best of circumstances, Anderson explained, the chemical reaction that produces energy in a fuel cell—like those being tested by some car companies—ends up wasting a quarter of the energy that could be transformed into electricity. This point is well recognized in the scientific community, but, to date, efforts to address the problem have proved fruitless.

Anderson blames the failure on a fundamental misconception as to the reason for the energy waste. The most widely accepted theory says impurities are binding to the platinum surface of the cathode and blocking the desired reaction.

“The decades-old surface-poisoning explanation is lame because there is more to the story,” Anderson said.

To understand the loss of energy, Anderson used data derived from oxygen-reduction experiments to calculate the optimal bonding strengths between platinum and intermediate molecules formed during the oxygen-reduction reaction. The reaction takes place at the platinum-coated cathode.

He found the intermediate molecules bond too tightly or too loosely to the cathode surface, slowing the reaction and causing a drop in voltage. The result is the fuel cell produces about .93 volts instead of the potential maximum of 1.23 volts.

To eliminate the loss, calculations show, the catalyst should have bonding strengths tailored so that all reactions taking place during oxygen reduction occur at or as near to 1.23 volts as possible.

Anderson said the use of volcano plots, which are a statistical tool for comparing catalysts, has actually misguided the search for the best one. “They allow you to grade a series of similar catalysts, but they don’t point to better catalysts.”

He said a catalyst made of copper laccase, a material found in trees and fungi, has the desired bonding strength but lacks stability. Finding a catalyst that has both is the challenge.

Anderson is working with other researchers exploring alternative catalysts as well as an alternative reaction pathway in an effort to increase efficiency.

Source: Case Western Reserve University

Researchers Create Highly Conductive and Elastic Conductors Using Silver Nanowires

Engineerblogger
July 19, 2012

The silver nanowires can be printed to fabricate patterned stretchable conductors.

Researchers from North Carolina State University have developed highly conductive and elastic conductors made from silver nanoscale wires (nanowires). These elastic conductors can be used to develop stretchable electronic devices.

Stretchable circuitry would be able to do many things that its rigid counterpart cannot. For example, an electronic “skin” could help robots pick up delicate objects without breaking them, and stretchable displays and antennas could make cell phones and other electronic devices stretch and compress without affecting their performance. However, the first step toward making such applications possible is to produce conductors that are elastic and able to effectively and reliably transmit electric signals regardless of whether they are deformed.

Dr. Yong Zhu, an assistant professor of mechanical and aerospace engineering at NC State, and Feng Xu, a Ph.D. student in Zhu’s lab have developed such elastic conductors using silver nanowires.

Silver has very high electric conductivity, meaning that it can transfer electricity efficiently. And the new technique developed at NC State embeds highly conductive silver nanowires in a polymer that can withstand significant stretching without adversely affecting the material’s conductivity. This makes it attractive as a component for use in stretchable electronic devices.

“This development is very exciting because it could be immediately applied to a broad range of applications,” Zhu said. “In addition, our work focuses on high and stable conductivity under a large degree of deformation, complementary to most other work using silver nanowires that are more concerned with flexibility and transparency.”

“The fabrication approach is very simple,” says Xu. Silver nanowires are placed on a silicon plate. A liquid polymer is poured over the silicon substrate. The polymer is then exposed to high heat, which turns the polymer from a liquid into an elastic solid. Because the polymer flows around the silver nanowires when it is in liquid form, the nanowires are trapped in the polymer when it becomes solid. The polymer can then be peeled off the silicon plate.

“Also silver nanowires can be printed to fabricate patterned stretchable conductors,” Xu says. The fact that it is easy to make patterns using the silver nanowire conductors should facilitate the technique’s use in electronics manufacturing.

When the nanowire-embedded polymer is stretched and relaxed, the surface of the polymer containing nanowires buckles. The end result is that the composite is flat on the side that contains no nanowires, but wavy on the side that contains silver nanowires.

After the nanowire-embedded surface has buckled, the material can be stretched up to 50 percent of its elongation, or tensile strain, without affecting the conductivity of the silver nanowires. This is because the buckled shape of the material allows the nanowires to stay in a fixed position relative to each other, even as the polymer is being stretched.

“In addition to having high conductivity and a large stable strain range, the new stretchable conductors show excellent robustness under repeated mechanical loading,” Zhu says. Other reported stretchable conductive materials are typically deposited on top of substrates and could delaminate under repeated mechanical stretching or surface rubbing.

The paper, “Highly Conductive and Stretchable Silver Nanowire Conductors,” was published in Advanced Materials. The research was supported by the National Science Foundation.


Source:  North Carolina State University

Researchers develop “nanorobot” that can be programmed to target different diseases

Engineerblogger

July 19, 2012

University of Florida researchers have moved a step closer to treating diseases on a cellular level by creating a tiny particle that can be programmed to shut down the genetic production line that cranks out disease-related proteins.

In laboratory tests, these newly created “nanorobots” all but eradicated hepatitis C virus infection. The programmable nature of the particle makes it potentially useful against diseases such as cancer and other viral infections.

The research effort, led by Y. Charles Cao, a UF associate professor of chemistry, and Dr. Chen Liu, a professor of pathology and endowed chair in gastrointestinal and liver research in the UF College of Medicine, is described online this week in the Proceedings of the National Academy of Sciences.

“This is a novel technology that may have broad application because it can target essentially any gene we want,” Liu said. “This opens the door to new fields so we can test many other things. We’re excited about it.”

During the past five decades, nanoparticles — particles so small that tens of thousands of them can fit on the head of a pin — have emerged as a viable foundation for new ways to diagnose, monitor and treat disease. Nanoparticle-based technologies are already in use in medical settings, such as in genetic testing and for pinpointing genetic markers of disease. And several related therapies are at varying stages of clinical trial.

The Holy Grail of nanotherapy is an agent so exquisitely selective that it enters only diseased cells, targets only the specified disease process within those cells and leaves healthy cells unharmed.

To demonstrate how this can work, Cao and colleagues, with funding from the National Institutes of Health, the Office of Naval Research and the UF Research Opportunity Seed Fund, created and tested a particle that targets hepatitis C virus in the liver and prevents the virus from making copies of itself.

Hepatitis C infection causes liver inflammation, which can eventually lead to scarring and cirrhosis. The disease is transmitted via contact with infected blood, most commonly through injection drug use, needlestick injuries in medical settings, and birth to an infected mother. More than 3 million people in the United States are infected and about 17,000 new cases are diagnosed each year, according to the Centers for Disease Control and Prevention. Patients can go many years without symptoms, which can include nausea, fatigue and abdominal discomfort.

Current hepatitis C treatments involve the use of drugs that attack the replication machinery of the virus. But the therapies are only partially effective, on average helping less than 50 percent of patients, according to studies
published in The New England Journal of Medicine and other journals. Side effects vary widely from one medication to another, and can include flu-like symptoms, anemia and anxiety.

Cao and colleagues, including graduate student Soon Hye Yang and postdoctoral associates Zhongliang Wang, Hongyan Liu and Tie Wang, wanted to improve on the concept of interfering with the viral genetic material in a way that boosted therapy effectiveness and reduced side effects.

The particle they created can be tailored to match the genetic material of the desired target of attack, and to sneak into cells unnoticed by the body’s innate defense mechanisms.

Recognition of genetic material from potentially harmful sources is the basis of important treatments for a number of diseases, including cancer, that are linked to the production of detrimental proteins. It also has potential for use in detecting and destroying viruses used as bioweapons.

The new virus-destroyer, called a nanozyme, has a backbone of tiny gold particles and a surface with two main biological components. The first biological portion is a type of protein called an enzyme that can destroy the genetic recipe-carrier, called mRNA, for making the disease-related protein in question. The other component is a large molecule called a DNA oligonucleotide that recognizes the genetic material of the target to be destroyed and instructs its neighbor, the enzyme, to carry out the deed. By itself, the enzyme does not selectively attack hepatitis C, but the combo does the trick.

“They completely change their properties,” Cao said.

In laboratory tests, the treatment led to almost a 100 percent decrease in hepatitis C virus levels. In addition, it did not trigger the body’s defense mechanism, and that reduced the chance of side effects. Still, additional testing is needed to determine the safety of the approach.

Future therapies could potentially be in pill form.

“We can effectively stop hepatitis C infection if this technology can be further developed for clinical use,” said Liu, who is a member of The UF Shands Cancer Center.

The UF nanoparticle design takes inspiration from the Nobel prize-winning discovery of a process in the body in which one part of a two-component complex destroys the genetic instructions for manufacturing protein, and the other part serves to hold off the body’s immune system attacks. This complex controls many naturally occurring processes in the body, so drugs that imitate it have the potential to hijack the production of proteins needed for normal function. The UF-developed therapy tricks the body into accepting it as part of the normal processes, but does not interfere with those processes.

“They’ve developed a nanoparticle that mimics a complex biological machine — that’s quite a powerful thing,” said nanoparticle expert Dr. C. Shad Thaxton, an assistant professor of urology at the Feinberg School of Medicine at Northwestern University and co-founder of the biotechnology company AuraSense LLC, who was not involved in the UF study. “The promise of nanotechnology is extraordinary. It will have a real and significant impact on how we practice medicine.”

Source: University of Florida

The Artificial Finger: New ultracapacitor delivers a jolt of energy at a constant voltage

Engineerblogger

June 19, 2012



To touch something is to understand it – emotionally and cognitive. It´s one of our important six senses, which we use and need in our daily lives. But accidents or illnesses can disrupt us from our sense of touch

To touch something is to understand it – emotionally and cognitive. It´s one of our important six senses, which we use and need in our daily lives. But accidents or illnesses can disrupt us from our sense of touch.

Now European researchers of the projects NanoBioTact and NanoBioTouch delve deep into the mysteries of touch and have developed the first sensitive artificial finger.
The main scientific aims of the projects are to radically improve understanding of the human mechano-transduction system and tissue engineered nanobiosensors. Therefore an international and multi disciplinary team of 13 scientific institutes, universities and companies put their knowledge together. “There are many potential applications of biometric tactile sensoring, for example in prosthetic limbs where you´ve got neuro-coupling which allows the limb to sense objects and also to feed back to the brain, to control the limb. Another area would be in robotics where you might want the capability to have sense the grip of objects, or intelligent haptic exploration of surfaces for example”, says Prof. Michael Adams, the coordinator of NanoBioTact.

The scientists have already developed a prototype of the first sensitive artificial finger. It works with an array of pressure sensors that mimic the spatial resolution, sensitivity and dynamics of human neural tactile sensors and can be directly connected to the central nervous system. Combined with an artificial skin that mimics a human fingerprint, the device´s sensitivity to vibrations is improved. Depending on the quality of a textured surface, the biomimetic finger vibrates in different ways, when it slides across the surface. Thereby it produces different signals and once it will get used by patients, they could recognise if the surface is smooth or scratchy. “The sensors are working very much like the sensors are doing on your own finger”, says physicist Dr. Michael Ward from the School of Mechanical Engineering at the University of Birmingham.

Putting the biomimetic finger on artificial limbs would take prostheses to the next level. “Compared to the hand prostheses which are currently on the market, an integrated sense of touch would be a major improvement. It would be a truly modern and biometric device which would give the patient the feeling as if it belonged to his own body”, says Dr. Lucia Beccai from the Centre for Micro-Robotics at the Italian Institute for Technology. But till the artificial finger will be available on large scale a lot of tests will have to be done. Nevertheless with the combination of computer and cognitive sciences, nano- and biotechnology the projects NanoBioTact and NanoBioTouch have already brought us a big step closer to artificial limbs with sensitive fingers!

Source: Youris