Bioengineering

SPARKy device helps amputees

dianeb — Thu, 07 Jan 2010 08:48:52 -0700

SPARKy prosthetic helps put spring into step from Keith Jennings on Vimeo.

by Skip Derra

Arizona State University researchers have developed a prosthetic device that literally puts the spring back into an amputee’s step. The ASU scientists have developed and refined SPARKy (for spring ankle with regenerative kinetics) into a smart, active and energy storing below-the-knee (transbitial) prosthesis.

SPARKy is the first prosthetic device to apply regenerative kinetics to its design, which resulted in a lightweight (four pound) device that allows the wearer to walk on grass, cement and rocks, as well as ascend and descend stairs and inclines.

SPARKY operates by employing a spring to store energy as the wearer walks during normal gait, said Thomas Sugar, an ASU associate professor of engineering at the Polytechnic campus who led the research. Sugar and his colleagues—ASU doctoral students Joseph Hitt and Matthew Holgate, as well as Barrett Honors College student Ryan Bellman—have been developing and refining SPARKy for three years as part of a U.S. Army grant.

SPARKy uses a robotic tendon to actively stretch springs when the ankle rolls over the foot, thus allowing the springs to thrust or propel the artificial foot forward for the next step. Because energy is stored, a lightweight motor is used to adjust the position of a finely tuned spring that provides most of the power required for gait.

“SPARKY basically removes the old passive devices and makes it an active device the wearer uses to attain normal gait, which for an amputee is a significant return to normal function,” Sugar said. SPARKy is not only an active prosthetic device, but it also allows a wider range of movement than previous devices, it weighs less and it causes less fatigue for the wearer.

The device is featured in the January 2010 National Geographic magazine in an article called Merging Man with Machine, the Bionic Age (http://ngm.nationalgeographic.com/2010/01/bionics/thiessen-photography).

SPARKy provides functionality with enhanced ankle motion and push-off power comparable to the gait of an able bodied individual. Sugar said the device reached its primary goal of returning the functionality of the amputee to his/her status prior to losing a limb.

The device is built to take advantage of the functional mechanics of gait. A gait cycle is the natural motion of walking, starting with the heel strike of one foot and ending with the heel strike of the same foot.

“The cycle can be split into two phases, stance and swing,” Sugar said. “We are concerned with storing energy and releasing energy (regenerative kinetics) in the stance phase.”

The mechanics of walking can be described as catching a series of falls, Sugar added. In SPARKy, a tuned spring (acting like the Achilles tendon) breaks the fall and stores energy as the leg rolls over the ankle during the stance phase.

While the project is nearing completion of its three year grant, there still is much more work to do to refine the device.

To date, SPARKy has allowed users to walk on inclines, steps and to walk backwards, not trivial tasks for people who have only had access to passive, and sometimes cumbersome, prosthetics. In the future, the team plans to make additional improvements to lower the weight of SPARKy by integrating very fast microprocessors and using the smallest lithium ion batteries.

“We want our finished device to allow soldiers to return to active duty,” Sugar said.

A faster path to patents

dianeb — Mon, 22 Jun 2009 13:30:25 -0600

by Joe Kullman

Antonio Garcia wants to see Arizona State University students make the leap “from being learners to becoming doers.” He’ll be helping them do that through his new ASU Foundation Professorship. Garcia is using resources provided by the professorship. He wants to establish a research center that offers mentorship to students who have ideas for improving health care technology.

The Center for Engineering and Translational Biomedicine becomes a reality this fall. Students are invited to submit their proposals for new medical devices and technologies.

ASU engineering student Mario Zamora (left) discusses a research project with bioengineering professor Antonio Garcia.

“The plan is for the center to become a resource for students. We want them to get involved in the process of innovation and to produce something meaningful—like a prototype device or a method that could be patented,” said Garcia, a professor in the Harrington Department of Bioengineering in ASU’s Ira A. Fulton School of Engineering.

Much of Garcia’s research has involved improving medical diagnostics. He has worked to develop better methods of administering medicinal drugs in places where access to hospitals, clinics and medical professionals is limited. That is often the case in rural areas, on battlefields, or in underdeveloped countries.

Initially, Garcia wants to bring to the center those students whose interests align with this area of research. The center is available to undergraduates to post-doctoral students.

“Typically, students get into research by assisting a professor or working in a research center. I am trying to change that paradigm,” he says. “For this new center, students will come to us with ideas. Faculty members will act in a supporting role.”

The center’s mission is clear. “We want to provide an environment to nurture fresh perspectives on how to solve problems. And we want to help students follow through on bringing their ideas to fruition,” Garcia says.

The opportunities won’t be limited to engineering students. Garcia sees possibilities for students in various areas of science, business, law and art to get involved.

Students from a range of backgrounds and areas of study will help the center foster the kind of teamwork and collaborative effort that often drives creativity, he adds.

“This reflects the thrust of our reorganization [of the Ira A. Fulton School of Engineering], the idea of stimulating students’ interest and creativity through hands-on, entrepreneurial ventures that encourage them not to wait until after they graduate to do actual engineering and research,” Garcia explains. “In this way the university becomes an ongoing resource for them as they begin their careers.”

Deirdre Meldrum is dean of the engineering school. “We provide students a range of entrepreneurial opportunities not found in any other engineering school,” Meldrum says. “We are expecting Tony Garcia’s new center to become the model for three or four additional centers. Those centers will allow our faculty and students to focus on solutions to the grand challenges of engineering in the 21st century, in areas such energy, sustainability and security."

The center will be launched with funds that come with Garcia’s appointment as an ASU Foundation Professor. For continued support, the center will seek sponsorships from corporations and foundations.

Garcia has done biomedical engineering research for two decades. He has also led efforts to improve education in engineering, science and mathematics.

For more information, contact Antonio Garcia, Ph.D., Harrington Department of Bioengineering, at tony.garcia@asu.edu

Brainy materials

dianeb — Thu, 14 May 2009 16:22:03 -0600

by Joe Kullman

So-called “smart” materials are the focus of much of today’s groundbreaking work in bioscience and bioengineering. It’s largely through the capabilities of nanotechnology that researchers are assembling tiny, intricate devices driven by a kind of built-in functional intelligence.

Such nanodevices are smart enough to perform myriad complex functions. They are helping scientists to advance medicine and medical science as well as to improve information technology. Other applications include enhancements to security and defense systems and optical imaging instruments, just to name a few.

Many of the possibilities are demonstrated in work led by biochemist and physicist Frederic Zenhausern. The scientist serves as director of the Center for Applied Nanobioscience at ASU’s Biodesign Institute. He also works as an investigator with the Molecular Diagnostics and Target Validation Division at the Translational Genomics Research Center (TGen) in downtown Phoenix. In his spare time he works as a professor in ASU’s Ira A. Fulton School of Engineering.

Zenhausern and colleagues have lots of projects in the works. They are developing “smart” hybrid nanomaterials and molecular bioassays. A bioassay is a technique for biological examination or analysis. The molecular bioassays can target areas in the body to deliver biomolecules and medication. Hybrid nanomaterials can be used to monitor internal conditions. Physicians might use these processes as an effective diagnostic tool. They could lead to customized therapy or prevention methods that are based on a patient’s unique molecular profile.

This research is at the forefront of the promising arena of “personalized medicine.” Health care will be tailored to a patient’s individual genomic profile.

Researchers are fashioning a toolbox full of nanoscale instruments. Some will be used to observe the behaviors of enzymes and proteins at the molecular scale. Similar devices already enable the real-time imaging of chemical and biological processes. They work at scales so small that until now they have been all but undetectable.

The new nanotools and methods are broadly adaptable. They can become part of portable devices for improving the health monitoring and safety of military forces in the field. They can be used to detect biohazards and defend against bioterrorist attacks. They will also help improve battery power for cell phones and computers.

“We are combining genomics, microbiology, microfluidics and nanotechnology like never before. This is all made possible by being able to manipulate materials at molecular levels,” Zenhausern says.

Work at the nanoscale allows for investigating biological interactions within the body’s cells at molecular levels. Such work holds great promise for revealing fundamental knowledge of complex biological systems. But nanotechnology goes even further. It probes deep into things once almost unimaginable.

Today, scientists and engineers are developing “nanostructures” equipped with their own internal power sources and sensor and signaling controls. Even more amazing, they actually are getting nanomaterials to build themselves, or “self-assemble,” into useful devices, Zenhausern explains.

“This all is brought about by the change in the characteristics and behaviors of materials when you go down the nanometer scale” he continues. “At the nanoscale, materials combine in ways that give them abilities to do certain things.

Nanostructures have the ability to self-assemble. Nanomaterials are easily injected into the body. Doctors can program them to seek out and attach to clusters of specific kinds of cells. Once at a target destination, the nanomaterial can use natural biochemical processes, or be controlled remotely. Doctors can use them deliver medicine or transmit diagnostic information.

Nature often forms complex structures as tools to make things work to its benefit. A large part of nanobiotechnology research involves trying to figure out the ways that nature works.

Says Zenhausern, “We study natural processes. We use them as models for sparking molecular evolution. Those processes provide designs. We use them to build nanodevices that will do what we want them to do. The possibilities for new nanomaterials and devices might be beyond what we can imagine even now.”

Read more about nanotechnology research in "To the edge of infinity...and beyond!" and "Mind benders: Understanding matter on the atomic scale."

Stimulated to heal

ovprea — Mon, 09 Mar 2009 12:47:39 -0600

by Melissa Crytzer Fry

Shelley Savage considers herself lucky. Despite having to rely on a wheelchair for the past 15 years, she knows that things could have been worse—possibly much worse. Savage was a passenger in a car accident during her college years. She broke her neck at the C6 vertebra.

The break was classified as an incomplete spinal injury. "Incomplete" means that some nerves are still connected above and below the injury site. For Savage, that equates to upper body control and some sensation throughout her lower torso.

"I was completely paralyzed for the first three months, so I know what a complete spinal injury is like," says the optimistic 38-year-old. "I am very grateful to have gotten some movement and feeling back in my body. It's still tough sometimes. But I'm able to have more independence and freedom."

Savage has never given up hope for a cure. She'd be lying, though, if she said the road has been easy.

"It's frustrating and discouraging. Once you become paralyzed, you're basically written off. You're told Ã¢â‚¬ËœThis is it. Don't expect much.'"

In addition, Savage says that physical therapy is only offered early after the injury. She also learned that reduced activity after a spinal cord injury can also lead to other complications. At age 30, she developed osteoporosis-related bone loss, despite a desire to remain actively engaged in physical therapy.

"You really have to fight for follow-up physical therapy," she explains. "Sometimes the only way you get the therapy is if you injure yourself."

Even then, therapy is offered at only a limited number of clinics. Most of that is on bulky and unaffordable exercise equipment.

James Abbas and Ranu Jung are working to change that scenario. Abbas and Jung are bioengineering professors at Arizona State University. They are co-directors of ASU's Center for Adaptive Neural Systems. Their research is focused on the use of electrical stimulation to contract paralyzed muscles.

Abbas and Jung are designing adaptive technology that actually interacts with the nervous system. The goal is to create devices that promote recovery and reorganization of the nervous system after spinal cord injury.

In one study, the ASU researchers are testing a hand-held muscle stimulator. The device is called CK200. It was developed by customKYnetics, Inc., a commercial partner working with the ASU engineers. Abbas is co-founder and part owner of the company. His efforts are focused on testing and understanding the company's products.

The CK200 is about the size of a paperback novel. It uses electrical stimulation to activate the muscles. Adhesive electrodes connected to the CK200 are placed on the skin. When activated, current passes through the electrodes and into the muscle, causing a muscle contraction.

"The idea is really based on a simple therapeutic principle. Do something. Be active. That's the best way for muscles to re-learn how to work," Abbas explains.

Participants in the ASU study had both complete and incomplete spinal cord injuries. Each person each received a hand-held CK200 unit for home use over the course of three months. After completing initial evaluations at ASU, they returned monthly for additional readings.

During each session, participants completed 60 muscle stimulations. Ankle weights were added periodically. When a subject could successfully complete three sessions without fatiguing the muscle, the weight was increased by a half-pound.

Members of the complete spinal injury group worked to stimulate the quadriceps muscles on each leg. The goal was to gain ability to complete standard leg lifts.

"This wasn't an aggressive therapy, although participants were getting some exercise and increased muscle strength," explains Abbas. "It was meant as an initial test of the device. We wanted to determine if it could generate smooth contractions of paralyzed muscles, and if the muscles got stronger."

The goal was different for the group with incomplete spinal cord injuries. The researchers wanted to know if participants were gaining the ability to voluntarily contract the muscles being targeted by the CK200.

"People with incomplete spinal cord injuries have great potential for relearning, which can impact their daily lives," Abbas says. "The thought is that, after repetitive muscle movement with the device, they'll eventually be able to control more and more of that movement, and hopefully wean off the stimulation."

The ASU study revealed that participants' muscles definitely got stronger through CK200 usage. Savage volunteered for the trial. She saw great gains for herself.

Early in the study, she could not complete a full set of leg extensions without ankle weights. At the end of three months, with the stimulator, she could complete the full set with five-pound ankle weights on each leg.

"I could feel the muscle tightening—the same kind of burn you feel if you've been lifting weights," Savage explains. "I wasn't even sure I had any muscle left after all these years. It was encouraging to realize that maybe the muscles weren't completely gone."

During the course of the study, the muscle mass in Savage's thighs increased by 11 percent.

"The numbers for individual participants progressed as the session went on," says Abbas. By the end of 2008, seven subjects had completed the full study. Six of those people reached the five-pound ankle weight maximum on at least one leg, with a muscle mass gain of at least 4 percent.

Researchers say that the health benefits of stimulation therapy can't be overlooked.

"Stimulation helps with the blood circulation in that region. It improves the overall health of the skin and muscles," adds Jung.

Muscle stimulation can also positively impact immune system response and hormonal response. What's more, such activity may be able to stave off diabetes and heart disease for people with paralysis, who are more susceptible to those diseases.

"Devices that use electrical stimulation exist in the marketplace. But they require someone to preset the values," explains Abbas.

For example, a physical therapist has to hand-set the controls before and after each and every desired movement. The CK200 is different. It has smarts as part of its internal computer that control the stimulation. The hand-held device continually adjusts the level of stimulation to achieve the desired movement pattern.

"It's personalized to each person who uses it," explains Abbas. It can sense when a muscle is fatigued and adjust the amount of stimulation on the next repetition—to maintain the same controlled movement.

But how does this smart technology actually work? Abbas says that CK200 uses an adaptive algorithm—a formula—programmed into the device, to compare the person's patterns of movement.

"The sensors on the skin read the movement patterns generated by the muscles," explains Jung. "The computer reviews that movement and compares it against a desired pattern of movement."

Preset with specific movement patterns, the CK200 stimulator can detect any movement errors and automatically adjust the pulses sent through the electrodes.

"The algorithm basically allows us to get the movement we're asking for," Abbas adds. He developed the basic adaptive algorithm used by the CK200.

"Initially, I was focused on programming the computer. I wasn't worried about making it smaller," Abbas continues. "But then I asked myself, Ã¢â‚¬Ëœwhat if we use this technology in a simple device for exercise?'" That question led to the birth of customKYnetics, Inc.

"We know the body is trying to heal itself during a spinal injury," explains Jung. "And we know neural systems can adapt—at the gene level, protein level, and cellular level. We're also trying to understand how and why that happens. And what can we do to promote that? Do stimulation devices expedite that process?"

Results from the initial studies hint that the answer is "yes." But the ASU bioengineers know their work is in its infancy. Currently, test participants included only those with spinal injuries that occurred years ago. Future studies may reveal that the potential for recovery increases if stimulation is introduced immediately after injury.

"We had to start with stable, healthy individuals. We had to know that it was the device helping them, and not the natural recovery process seen in the first few months after injury," explains Abbas.

One thing is certain: as the studies change in design, so, too, will the evolution of portable stimulation devices like the CK200. In the future, the device may even have applications for knee injury rehabilitation, and for more aggressive therapy programs. Someday, it is hoped these devices will be accessible and available for home use.

As Shelley Savage says, "They're getting close. Any progress being made brings us one step closer to a cure." When she walks again—not if—Savage says her first steps will be among Europe's medieval castles.

ASU studies on neuromuscular are supported by the National Institutes of Health and Science Foundation Arizona. For more information, contact James Abbas, Ph.D., or Ranu Jung, Ph.D., ASU Center for Adaptive Neural Systems, Ira A. Fulton School of Engineering, 480.965.9521 or 480.965.9052. Send e-mail to: Jimmy.Abbas@asu.edu and Ranu.Jung@asu.edu

Bioengineering student research helps disabled Africans

ovprea — Mon, 26 Jan 2009 14:32:55 -0700

by Joe Kullman

Mona Aoufe wants whatever endeavors she pursues in her future career to be as fulfilling as her final major assignment to earn an undergraduate engineering degree at Arizona State University.

She joined about 20 students in the Harrington Department of Bioengineering in the Ira A. Fulton School of Engineering in senior-year research projects to design and assemble medical devices for disabled villagers in a poverty-stricken south-central region of the African country of Malawi.

"We put a lot of passion into it," Aoufe says. "It wasn't your typical class project. We were working for more than a good grade—we wanted to provide things for people to make their lives better."

Customized wheelchairs, orthopedic braces and therapeutic instruments are among the devices to be delivered to the village of Njewa in early summer of 2009.

It will be the second shipment in the past three years of devices designed and built by ASU engineering students to be brought to Malawians under the supervision of Jan Snyder, a science education program manager in ASU's School of Materials.

For Snyder, it's part of a family project undertaken with his wife, Clarice, that he intends to expand in coming years.

Jan Snyder, an ASU engineering education specialist, meets with villagers in Malawi during a trip to Africa in 2006.

Witnessing deprivation
Snyder first visited Africa as an undergraduate biology student in the 1960s. He was drawn by the continent's plants and animals, but "became equally interested in the people," he says.

That concern intensified years later when one of his three daughters, Jessi Jean, spent a semester in Kenya in 1997 as part of her college studies, and from 2003 to 2005 worked with the Peace Corps in Malawi. During that time, Snyder, his wife and their three other children visited Jessi Jean and lived for six weeks in a village in the Nkhotakota region of central Malawi.

There they witnessed a disadvantaged and even dangerous way of life. "We saw life in the raw and death in the raw," he says.

The family saw firsthand the problems of poor sanitation, the severe lack of health care and resulting health problems. AIDS, tuberculosis, malaria and polio still afflict many, and estimates are that seven to 10 percent of the more than 13 million Malawians are physically disabled in some way, Snyder says.

Vincent Pizziconi, an ASU associate professor of bioengineering, learned of Snyder's desire to help the Malawians and suggested Snyder videotape interviews with disabled villagers about their disabilities when he visited Africa in 2006.

Pizziconi showed the videos in his class and then challenged students with assignments for their senior-year "capstone" research projects to produce devices for those individuals.

"When we saw the people on the videos we began to feel a connection to them," recalls Leila Kabiri, who earned her bioengineering degree in 2008. "It made us want to be successful for them."

Engineering challenges
Kabiri helped design and build a wheelchair for a Mawali woman named Ida, who had been partially paralyzed at age 20 from a condition that was never diagnosed.

She and fellow students had to manufacture the devices not only to fit the conditions of the disabled individuals, but had to construct them with materials that will enable the Malawians to repair or rebuild devices in the future using the limited materials available in their country.

The materials also had to be resilient enough to hold up in the rough terrain and environmental conditions of the region.

Kabiri's project team used bicycle tires for the wheelchair, along with a cushion stuffed with pinto beans coated with a chemical that helps keep the cushion dry in a humid climate.

Monica Lopez helped make an orthotic device for a young Malawian girl with an arm crippled by polio when she was an infant.

She and her project team used Velcro, elastic bands, and spring-loaded components so the device would be sufficiently adjustable and flexible to enable movements necessary for the girl to use it to improve her ability to stretch her arm and grip with her hand.

Like other project teams, Kabiri's and Lopez's teams consulted specialists in medical fields focused on treating the disabled. They also had to test the devices and ensure the instruments adhered to strict design specifications stipulated by government regulatory agencies.

"It was hard, but it was an experience that gave us a real idea of what kinds of challenges you're going face as a bioengineer," says Lopez, who plans to go to medical school.

Selfless acts
It was the opportunity to help an individual in need in a deprived country that made the project special. "It wasn't just something we were doing for ourselves. That made it meaningful," Lopez says.

Says Kabiri, "It just feels great to make something that someone can use to help themselves. I'm so excited to send the wheelchair to Ida and see if she likes it."

Aoufe, who plans to pursue a dual master's degree in business and health care administration, worked with a team that built a customized tricycle for another partially paralyzed Malawi woman named Elizabeth.

"The project was one of the most rewarding experiences I've had," she says, "because this was a selfless act. All we cared about was making something for Elizabeth."

Sharing technology
Snyder wants to make the medical-device project a first step toward larger goals.

He is talking to educators in Malawi about teaming with ASU to provide the country programs to train its own engineers. He sees opportunities for engineers here to work with Malawians on employing modern technologies to provide the country with better infrastructure and sources of energy.

He hopes to someday to see establishment of a college-level technical school, and a school for Malawian women and girls, who rarely get formal education beyond early elementary grades.

"Education and the sharing of technology can offer the people in African countries opportunities to become economically sustainable," Snyder says. "The solution to their problems has to start with instilling in them the spirit of innovation, imagination and self-sufficiency."

Until recently, the effort had been funded solely by Snyder and his wife. They now have additional financial support through a fledgling nonprofit, Sustainable Resources Ltd., founded by the Snyders and James and Alice Broscheid, who share the Snyders" interest in humanitarian efforts for Africa.

James Broscheid is a project manager with Siemens AG, one of the world's largest engineering and electronics conglomerates. He is now studying at ASU's downtown Phoenix campus for a degree in nonprofit organization management. Alice Broscheid works with a mental health counseling facility.

Snyder would like to see more faculty and students in engineering and ASU schools and colleges find ways to aid the cause through research and course projects.

ASU faculty who mentored students involved in the project include: Kristinn Heinrichs, a specialist in rehabilitation neuroscience and rehabilitation engineering; Richard Filley, director of the engineering school's Global Futures Initiative; Jiping He, a professor of bioengineering and director of the Center for Neural Interface Design; Ranu Jung, an associate professor of bioengineering and co-director of the Center for Adaptive Neural Systems; and Joseph Peles, an adjunct professor in the bioengineering department.

"If we had more people in the ASU community, with their knowledge and abilities, spearheading these efforts, it could have a great impact on the lives of many Africans," he says.

For more information about the Sustainable Resources Ltd. and the Malawi project, visit Sustainable Resources Ltd.

Cells as nanotechnology factories

ovprea — Thu, 06 Nov 2008 14:13:37 -0700

by Joe Caspermeyer

In the tiny realm of nanotechnology, scientists have used a wide variety of materials to build atomic scale structures. But just as in the construction business, nanotechnology researchers can often be limited by the amount of raw materials. Now, ASU chemist Hao Yan has avoided these pitfalls by using cells as factories to make DNA-based nanostructures inside a living cell.

The results were published in the early online edition of the Proceedings of the National Academy of Sciences.

Yan specializes in a fast-growing field within nanotechnology Ã¢Å½Â¯commonly known as structural DNA nanotechnologyÃ¢Å½Â¯ that uses the basic chemical units of DNA, abbreviated as C, T, A, or G, to self-fold into a number of different building blocks that can further self-assemble into patterned structures.

"This is a good example of artificial nanostructures that can be replicated using the machineries in live cells," says Yan. "Cells are really good at making copies of double-stranded DNA and we have used the cell like a copier machine to produce many, many copies of complex DNA nanostructures."

DNA nanotechnologists have made some very exciting achievements during the past five to 10 years. But DNA nanotechnology has been limited by the need to chemically synthesize all of the material from scratch. To date, it has strictly been a test tube science, where researchers have developed many toolboxes for making different DNA nanostructures to attach and organize other molecules including nanoparticles and other biomolecules.

"If you need to make a single gram of a DNA nanostructure, you need to order one gram of the starting DNA materials. Scientists have previously used chemical methods to copy branched DNA structures, and there has also been significant work in using long-stranded DNA sequences replicated from cells or phage viruses to scaffold short helper DNA sequences to form 2-D or 3-D objects," says Yan.

"We have always dreamed of scaling up DNA nanotechnology. One way to scale that it up is to use the cellular system because simple DNA can be replicated inside the cell. We wanted to know if the cell's copy machine could tolerate single stranded DNA nanostructures that contain complicated secondary structures."

To test the nanoscale manufacturing capabilities of cells, Yan and his fellow researchers, Chenxiang Lin, Sherri Rinker and Yan Liu at ASU and their collaborators Ned Seeman and Xing Wang at New York University went back to reproducing the very first branched nanostructure made up of DNA- a cross-shaped, four-arm DNA junction and another DNA junction structure containing a different crossover topology.

To copy these branched DNA nanostructures inside a living cell, the ASU and NYU research team first shipped the cargo inside a bacteria cell. They cut and pasted the DNA necessary to make these structures into a phagemid, a virus-like particle that infects a bacteria cell. Once inside the cell, the phagemid used the cell just like a photocopier machine to reproduce millions of copies of the DNA. By theoretically starting with just a single phagemid infection, and a single milliliter of cultured cells, Yan found that the cells could churn out trillions of the DNA junction nanostructures.

The DNA nanostructures produced in the cells were also found to fold correctly, just like the previously built test tube structures. According to Yan, the results also proved the key existence of the DNA nanostructures during the cell's routine DNA replication and division cycles. "When a DNA nanostructure gets replicated, it does exist and can survive the complicated cellular machinery. And it looks like the cell can tolerate this kind of structure and still do its job. It's amazing," said Yan.

Yan acknowledges that this is just the first step, but foresees there are many interesting DNA variations to consider next. "The fact that the natural cellular machinery can tolerate artificial DNA objects is quite intriguing, and we don't know what the limit is yet."

Yan's group may be able to change and evolve DNA nanostructures and devices using the cellular system and the technology may also open up some possibilities for synthetic biology applications.

"I'm very excited about the future of DNA nanotechnology, but there is a lot of work to be done. An interesting research topic to pursue is the interface of DNA nanostructures with live cells; it is full of opportunities," said Yan.

Yan is a researcher with the Biodesign Institute at ASU. For more information, contact Hao Yan, Department of Chemistry and Biochemistry, School of Life Sciences, College of Liberal Arts and Sciences, 480.727.8570. Send email to hao.yan@asu.edu

Nanojewels made easy

ovprea — Thu, 07 Aug 2008 12:09:55 -0600

by Joe Kullman

Butterfly wings, peacock feathers, opals and pearls are some of nature's jewels that use nanostructures to dazzle us with color. It's accomplished through the way light reaches our eyes after passing through the submicroscopic mazes within these materials.

The seemingly effortless way that nature creates this effect is now rivaled by a rapid and simple method developed through a collaboration of researchers from North Carolina State University (NCSU), Arizona State University (ASU) and the Universidad Complutense de Madrid (UCM).

Professor Orlin Velev and graduate student researcher Vinayak Rastogi in the Department of Chemical Engineering at NCSU have shown how colloid chemistry methods originally used to form particle aggregates from nanoparticles can be used to quickly make particles with dazzling colors simply by letting a suspension of nanoparticles dry on a superhydrophobic surface.

Superhydrophobicity is a property of a material that repels water like ducks' feathers or lotus leaves. It has been used commercially in textiles, coatings and building materials.

The basic idea behind the process is akin to stacking round fruits or vegetables in a supermarket produce bin in high, neat rows to keep the produce from falling to the floor as customers pick them out. Doing this with nanoscale particles of different sizes leads to opalescence, since some colors of light are reflected differently depending on the size of the holes between the nanoparticles and the angle from which they are viewed.

Normally, carefully arranging the nanoparticles in neat rows requires a complex series of steps with oily solvents and water mixtures requiring extensive washing afterwards to remove the solvents.

Now, with the help of researchers at ASU, this process has been made as simple as placing a drop on a superhydrophobic surface and letting it dry for one to two hours.

The researchers call these one- to two-millimeter particles "nanojewels."

Velev and Rastogi of NCSU developed the method with help of several colleagues, including: Manuel Marquez, an adjunct professor in the Harrington Department of Bioengineering in ASU's Ira A. School of Engineering, and Antonio Garcia, a professor in the bioengineering department and director of the Laboratory for Personalized Molecule Measurement; and professors Sonia Melle and Oscar Calderon in the School of Optics at UCM.

Rastogi's presentation at the 82nd American Chemical Society Colloid & Surface Science Symposium on June 18, 2008 titled "Synthesis of Light-Diffracting Colloidal Crystal Assemblies from Microspheres and Nanoparticles in Droplets on a Superhydrophobic Surface" and a paper just published in the journal Advanced Materials (published online: July 28, 2008), authored by these researchers, describes how for the first time superhydrophobic surfaces are shown to play an important role in making new materials.

In the paper, they describe how different nanoparticles of various sizes can produce "nanojewels" of various colors that display different optical properties.

"These nanojewels can potentially find application in photonics, drug delivery, special coatings, sensors and microfluidics," Velev explains.

Indeed, many researchers around the world are working on ways to make similar two-dimensional and three-dimensional photonic crystals to fabricate light-emitting diodes, optical fibers for communications, submicroscopic lasers, ultrawhite pigments, antennas and reflectors, and optical integrated circuits.

The biggest stumbling blocks in making these materials is finding ways of making photonic crystals with uniform properties in very large quantities and in minimizing imperfections in structure that reduce the quality of the final product. This new process is certainly easy to replicate to make large quantities, and superhydrophobic surfaces lead to structures that naturally form ordered structures.

Superhydrophobic surfaces allow nanojewels to be created from a single drop of water containing nanoparticles, because of several effects.

First, the drop stays in the shape of a ball because water does not spread on it while the nanoparticles are held in the drop due to the surface tension of water.

Compared to drying the drop in air, which is a fast evaporation process that causes the water in the drop to distort and flow, the drop gently dries on the superhydrophobic surface. This lets the nanoparticles get as close to each other as possible, swirling in a slow circular motion until all of the water evaporates.

When nanoparticles of two different sizes are used in the same drop, the smaller ones move to the surface of the drop while the bigger ones stay in the middle. This is because the smaller ones have more Brownian motion and are elevated to the surface with the water molecules that are subsequently evaporating at the surface, leaving all of the nanoparticles behind to form the nanojewels.

"Besides the dazzling look of these nanojewels, the most exciting thing about this work is that it opens up many interesting possibilities in quickly and inexpensively making new materials with nanoparticles," Marquez says.

"By understanding how different particle sizes determine the colors produced, these nanojewels can be designed for applications in optical communication systems," Melle adds.

As more nanoparticles and nanostructures come into the marketplace, technologies that can quickly assemble the structures so that their unique size and properties can be employed in new devices will be important to the growth of nanotechnology and related industries.

Referenced Article: "Synthesis of Light-Diffracting Assemblies from Microspheres and Nanoparticles in Droplets on a Superhydrophobic Surface", Vinayak Rastogi, Osca G. Calderon, Antonio A. Garcia, Manuel Marquez, and Orlin Velev, Advanced Materials, (Early View) Published online 28 Jul 2008 (DOI 10.1002/adma.200703008).

For more information, contact Antonio Garcia, Harrington Department of Bioengineering, 480.965.8798, tony.garcia@asu.edu

Media inquiries contact Joe Kullman, 480.965.8122 (direct line), 480.773.1364 (mobile), joe.kullman@asu.edu

Microbial fuel cells generate electricity from waste

ovprea — Thu, 03 Jan 2008 11:17:21 -0700

by Joe Caspermeyer

Researchers at the Biodesign Institute are using the tiniest organisms on the planet–bacteria–as a viable option to make electricity. In a new study featured in the journal Biotechnology and Bioengineering, lead author Andrew Kato Marcus and colleagues CÃƒÂ©sar Torres and Bruce Rittmann have gained critical insights that may lead to commercialization of a promising microbial fuel cell (MFC) technology.

"We can use any kind of waste, such as sewage or pig manure, and the microbial fuel cell will generate electrical energy," said Marcus, a Civil and Environmental Engineering graduate student and a member of the institute's Center for Environmental Biotechnology. Unlike conventional fuel cells that rely on hydrogen gas as a fuel source, the microbial fuel cell can handle a variety of water-based organic fuels.

"There is a lot of biomass out there that we look at simply as energy stored in the wrong place," said Bruce Rittmann, director of the center. "We can take this waste, keeping it in its normal liquid form, but allowing the bacteria to convert the energy value to our society's most useful form, electricity. They get food while we get electricity."

Microbe Power : The microbial fuel cell (MFC), shown in this tabletop setup, can take common sources of organic waste such as human sewage, animal waste, or agricultural runoff and convert them into electricity.

Waste not
Bacteria have such a rich diversity that researchers can find a bacterium that can handle almost any waste compound in their daily diet. By linking bacterial metabolism directly with electricity production, the MFC eliminates the extra steps necessary in other fuel cell technologies. "We like to work with bacteria, because bacteria provide a cheap source of electricity," said Marcus.

There are many types of MFC reactors and research teams throughout the world (http://microbialfuelcell.org). However, all reactors share the same operating principles. All MFCs have a pair of battery-like terminals: an anode and cathode electrode. The electrodes are connected by an external circuit and an electrolyte solution to help conduct electricity. The difference in voltage between the anode and cathode, along with the electron flow in the circuit, generate electrical power.

In the first step of the MFC, an anode respiring bacterium breaks down the organic waste to carbon dioxide and transfers the electrons released to the anode. Next, the electrons travel from the anode, through an external circuit to generate electrical energy. Finally, the electrons complete the circuit by traveling to the cathode, where they are taken up by oxygen and hydrogen ions to form water.

What is the matrix?
"We knew that the MFC process is relatively stable, but one of the biggest questions is: How do the bacteria get the electrons to the anode?" said Marcus.

The bacteria depend on the anode for life. The bacteria at the anode breathe the anode, much like people breathe air, by transferring electrons to the anode. Because bacteria use the anode in their metabolism, they strategically position themselves on the anode surface to form a bacterial community called a biofilm.

Bacteria in the biofilm produce a matrix of material so that they stick to the anode. The biofilm matrix is rich with material that can potentially transport electrons. The sticky biofilm matrix is made up of a complex of extracellular proteins, sugars, and bacterial cells. The matrix also has been shown to contain tiny conductive nanowires that may help facilitate electron conduction.

"Our numerical model develops and supports the idea that the bacterial matrix is conductive," said Marcus. In electronics, conductors are most commonly made of materials like copper that make it easier for a current to flow through . "In a conductive matrix, the movement of electrons is driven by the change in the electrical potential." Like a waterfall, the resulting voltage drop in the electrical potential pushes the flow of electrons.

The treatment of the biofilm matrix as a conductor allowed the team to describe the transport of electrons driven by the gradient in the electrical potential. The relationship between the biofilm matrix and the anode could now be described by a standard equation for an electrical circuit, Ohm's law.

Within the MFC is a complex ecosystem where bacteria are living within a self-generated matrix that conducts the electrons. "The whole biofilm is acting like the anode itself, a living electrode," said Marcus. "This is why we call it the Ã¢â‚¬Ëœbiofilm anode.'"

The Inner Life of a MFC : Bacteria have evolved to utilize almost any chemical as a food source. In the MFC, bacteria form a biofilm, a living community that is attached to the electrode by a sticky sugar and protein coated biofilm matrix. When grown without oxygen, the byproducts of bacterial metabolism of waste include carbon dioxide, electrons and hydrogen ions. Electrons produced by the bacteria are shuttled onto the electrode by the biofilm matrix, creating a thriving ecosystem called

Life at the Jolt
The concept of the "biofilm anode" allowed the team to describe the transport of electrons from bacteria to the electrode and the electrical potential gradient. The importance of electrical potential is well known in a traditional fuel cell, but its relevance to bacterial metabolism has been less clear. The next important concept the team had to develop was to understand the response of bacteria to the electrical potential within the biofilm matrix.

Bacteria will grow as long as there is an abundant supply of nutrients. Jacques Monod, one of the founding fathers of molecular biology, developed an equation to describe this relationship. While the team recognized the importance of the Monod equation for bacteria bathed in a rich nutrient broth, the challenge was to apply the Monod equation to the anode, a solid.

Previous studies have shown that the rate of bacterial metabolism at the anode increases when the electrical potential of the anode increases. The researchers could now think of the electrical potential as fulfilling the same role as a bacterial nutrient broth. The team recognized that the electrical potential is equivalent to the concentration of electrons; and the electrons are precisely what the bacteria transfer to the anode.

Equipped with this key insight, the team developed a new model, the Nernst-Monod equation, to describe the rate of bacterial metabolism in response to the "concentration of electrons" or the electrical potential.

Promise meeting potential
In their model, the team identified three crucial variables to controlling an MFC: the amount of waste material (fuel), the accumulation of biomass on the anode, and the electrical potential in the biofilm anode. The third factor is a totally novel concept in MFC research.

"Modeling the potential in the biofilm anode, we now have a handle on how the MFC is working and why. We can predict how much voltage we get and how to maximize the power output by tweaking the various factors," said Marcus. For example, the team has shown that the biofilm produces more current when the biofilm thickness is at a happy medium, not too thick or thin.

"If the biofilm is too thick," said Marcus, "the electrons have to travel too far to get to the anode. On the other hand, if the biofilm is too thin, it has too few bacteria to extract the electrons rapidly from the fuel."

To harvest the benefits of MFCs, the research team is using its innovative model to optimize performance and power output. The project, which has been funded by NASA and industrial partners OpenCEL and NZLegacy, lays out the framework for MFC research and development to pursue commercialization of the technology.

Andrew Kato Marcus is a Ph.D. student in Civil and Environmental Engineering. Bruce Rittmann, Ph.D., is the director of the Center for Environmental Biotechnology at ASU's Biodesign Institute. Rittmann is a professor in the Department of Civil and Environmental Engineering at the Ira A. Fulton School of Engineering and a member of the National Academy of Engineering.

This article first appeared on the Biodesign Institute's news page.

Researchers design new prosthesis

ovprea — Mon, 06 Aug 2007 15:15:49 -0600

by Christine Lambrakis

Researchers at ASU's Polytechnic campus and the Military Amputee Research Program at Walter Reed Army Medical Center are teaming up to create the next generation of powered prosthetic devices based on lightweight, energy-storing springs.

The device, nicknamed SPARKy—short for Spring Ankle with Regenerative Kinetics—will be the first-of-its-kind smart, active and energy-storing transtibial, or below-the-knee, prosthesis.

Doctoral candidates Matt Holgate, left and Joe Hitt pose with SPARKy, the name given to the Spring Ankle using Regenerative Kinetics.

Existing technology in prosthetic devices is largely passive and requires amputees to use 20 percent to 30 percent more energy to propel themselves forward when walking compared to an able-bodied person, according to Thomas Sugar, ASU assistant professor of engineering at the Polytechnic campus.

Once complete, SPARKy is expected to provide functionality with enhanced ankle motion and push-off power comparable to the gait of an able-bodied individual.

"A gait cycle describes the natural motion of walking starting with the heel strike of one foot and ending with the heel strike of the same foot," Sugar says. "The cycle can be split into two phases: stance and swing. We are concerned with storing energy and releasing energy (regenerative kinetics) in the stance phase."

The mechanics of walking can be described as catching a series of falls, Sugar says. In the team's device, a tuned spring brakes falls and stores energy as the leg rolls over the ankle during the stance phase, similar to the Achilles tendon.

Sugar's team, made up of doctoral students Joseph Hitt and Matthew Holgate, and Barrett Honors College student Ryan Bellman, have coined SPARKy a "robotic tendon" because of its bionic properties.

"What we hope to create is a robotic tendon that stretches springs when the ankle rolls over the foot, thus allowing the springs to thrust or propel the artificial foot forward for the next step," Sugar says. "Because energy is stored, a lightweight motor can be used to adjust the position of a uniquely tuned spring that provides most of the power required for gait. Thus, less energy is required from the individual."

The team is the first to apply regenerative kinetics to design a lightweight prosthetic device. Others are using large motors combined with harmonic drives, a monopropellant or extremely high-pressure oil.

Sugar's team already has proof that SPARKy is working. In recent experiments with able-bodied subjects outfitted with a robotic ankle orthosis, or a powered-assist device, the researchers found that the spring and motor combination was able to amplify the motor power by threefold. This significant finding allows SPARKy to be downsized from a 6- to 7- kilogram motor system to a 1-kilogram (2.2 pound) system, which is significant weight savings for those who wear a prosthesis.

"We expect this device to revolutionize prosthetics, and it will be especially helpful for military personnel wounded in active duty," Hitt says.

The project is a multiphased effort led by ASU's Human Machine Integration Lab, Arise Prosthetics and Robotics Group Inc. Arise Prosthetics is helping in the fitting of the device, and Robotics Group Inc. is designing embedded processors and motor amplifiers.

The first phase of SPARKy featuring the robotic tendon is expected to be ready for demonstration in December.

"I will know it is successful when a wounded solider is able to walk using the device on a treadmill," says Sugar about this phase.

The project will culminate with the functionality to support daily walking, which is expected in 2009.

This article was first published in ASU Insight.

For more information, contact Christine Lambrakis at 480.727.117. Send e-mail to lambrakis@asu.edu

When science gels with medicine

ovprea — Mon, 14 May 2007 18:09:51 -0600

by Melissa Crytzer Fry

Super glue, organic solvents, and stainless steel springs seem better suited for high school science competitions than for treatment of defective blood vessels and cancerous tissues. Such products, however, are frequently used to repair the human body.

Brent Vernon is focused on creating a safer, more efficient alternative. A bioengineering professor at Arizona State University's Ira Fulton School of Engineering, Vernon is developing temperature-sensitive polymer gels that can be injected into the vascular system to stop unwanted blood flow. They can also be used to deliver drugs to targeted areas of the body.

The gels are particularly useful in treating dangerous, bulging blood vessels known as aneurysms. "With an aneurysm, a bubble forms off the blood vessel," Vernon explains. "You could use the gel to fill up that bubble and keep it from rupturing."

Other uses include delivery of chemotherapy drugs. "Because the drugs are toxic, you can't give a very high concentration," Vernon says. "But if you put the drug inside a gel and it can diffuse out slowly, then you can give a lot more drug. One dose could contain enough for slow release delivery over an entire week or even a month."

Many materials, when under constant stress and temperature in the body, begin to swell or flow out of the target region. As a result, they block undesirable vessel regions. Others gel too quickly before they enter the blood stream. They get trapped in catheters and never reach their destination. Other materials don't solidify quickly enough in the blood vessel. They end up being distributed elsewhere in the body away from where they are needed.

Vernon has developed gels that solve many of those problems. To make them, he creates long chains of molecules called polymers in his laboratory. To create polymers, he combines a series of smaller molecules in organic solvents. He then purifies the new substances and dries them to remove unwanted solvent.

The end result is a powdery material that dissolves when combined with liquid. It remains as a liquid at room temperature, but gels at body temperature when injected.

These temperature-responsive materials are known as in situ gels. Such gels form in two ways: physical and chemical. The material begins to gel when injected, but solidifies over time. This helps help the gel stay in place.

"At body temperature, the polymers in physical gels precipitate into a solid form out of the injectable solution. They entangle around each other, creating a spaghetti-like mass," explains Vernon. "Conversely, chemical gels involve a chemical bond, or cross-link, between the polymers. Materials that are both physical and chemical will gel by entanglement and by cross-linking." The result will be stronger, more effective gels.

While degradable gels have been used in drug delivery for years, the non-degradable endovascular application is unique. Within three to four years, Vernon expects that patients with vascular problems will benefit from the myriad computer analyses and cell culture studies conducted in his lab.

"The implications are far-reaching," says Vernon. He and fellow ASU researchers at the Harrington Department of Bioengineering, Michael Caplan, Bae Hoon Lee, and Christine Pauken, are beginning to study the relationship between polymer gels and stem cell production.

ASU's polymer gels could feature a scaffold that is ideal for carrying signals that "tell" stem cells to divide and grow, he says. Mass production of stem cells could impact maladies ranging from Parkinson's disease and arthritis to cancer and diabetes.

Brent Vernon's research is supported by the National Institutes of Health and Arizona Technology Enterprises, in collaboration with the Barrow Neurological Institute in Phoenix.