UIC Engineers to Develop Models for 'Self-Healing' Materials

Materials engineered to self-repair or self-heal have been the subject of Hollywood films for decades. While prototypes of materials that self-seal cracks in buildings, roadways, airplanes, spacecraft and other devices are now under development, engineers still face the challenge of turning the multiple physical and mechanical processes of these materials into mathematical models for use by developers.

Two University of Illinois at Chicago engineers -- Eduard Karpov, assistant professor of civil and materials engineering and Elisa Budyn, UIC assistant professor of mechanical and bioengineering -- are up to the task. They have just received a three-year, $400,000 grant from the National Science Foundation to develop novel methods involving description of the relevant multi-physics phenomena that can be used for computer-based design and property predictions of self-healing materials and bone tissue.

"To model different kinds of physical processes together within a single numerical framework is a big challenge," said Karpov. The goal is to develop a theoretical and computational framework to write modeling software used by engineers and developers.

"The main questions include how to couple chemical reactions and the mechanics of materials," Karpov said. "For example, crack propagation inside a material and capillary transport of the healing agent along the crack."

"Another question is how biological tissue, such as bone, heals when stimulated mechanically," said Budyn. "For example, it has been observed that bone can grow inside the pores of an implant."

Karpov is a specialist in a field called multiphysics modeling, which examines multiple concurrent physical phenomena within a single numerical framework. Because of the intrinsic multi-physics nature of the behavior and performance of these new self-healing materials, the usual theories for material mechanics are not applicable.

Budyn is a specialist in biomechanics and fracture mechanics, which models the mechanics of biological tissues and their failure.

Karpov and Budyn's research will help in writing new rules of the game.

Self-healing materials are inspired by such biological processes as bone ingrowths, skin wounds and muscle tears that heal by themselves. "We have a lot to learn from nature," Budyn said.

Understanding biological tissues is key to the ability to engineer materials such as metals, concrete and polymer composites with self-healing properties that promise to minimize the possibility of catastrophic failure in devices such as airplanes and spacecraft, or in hard-to-repair areas such as electronic circuit boards or human medical implants.

"There are so many practical applications," Karpov said. "It's very exciting."

For more information about UIC, visit www.uic.edu.

Making Nanowires More Electrically Stable

It's widely predicted that future electronics will largely depend on something really small -- nanomaterials used for building nanoelectronics. A key component of these tiny circuits is stable nanowires that work reliably for a decade or more. Currently, however, nanowires often fail after anywhere from a few days to a few months, due to prolonged electrical stressing.

Carmen Lilley, assistant professor of mechanical and industrial engineering at the University of Illinois at Chicago, is working on new procedures for making nanowires more electrically stable -- and hence more reliable. She was recently awarded a $505,532 National Science Foundation Faculty Early Career Award to help advance her project.

"My idea is to look at the physics of failure," she said. "How do these systems fail when stressed electrically? If we can develop a basic understanding of the mechanisms that control failure and a way to model these mechanisms, we can create material designs with predictable behavior."

Lilley's research focuses on studying properties of single crystals of common conductor metals such as gold, silver, copper, nickel and iron, and their unusual behavior characteristics at the nanoscale.

"At these smaller scales, the electrical resistivity of the structure changes," she said. "Single crystalline materials are of interest because we can use them to control the material uncertainties that influence typical experiments such as isolating electrical resistivity measurements from grain boundary effects, surface contaminant and roughness effects. What is the basic electrical resistivity at different sizes within the nanoscale?"

Lilley's goal is to create a basic design scheme to build stable nanowires for any application. For future highly integrated circuits and nanoelectronics, nanowires are the "essential building block," she said. "But to be successful, they must be stable, and that's a considerable challenge."

Lilley plans to use part of her grant to continue an ongoing effort to attract underrepresented minorities to engineering careers. One effort is the launch of a graduate mentoring program called "Preparing for Academic Careers in Engineering," or PACE. This program is sponsored by Women in Science and Engineering, the UIC College of Engineering and the department of mechanical and industrial engineering.

She also hopes to give undergraduate assistants more hands-on laboratory experience, and to bring students from Chicago Public Schools to UIC to see work in the lab and view some of the breathtaking images produced by instruments such as scanning electron microscopes.

"These beautiful images often have artwork properties. For the visiting kids, it can spark an interest."

NSF's Faculty Early Career Development award is its most prestigious honor given to junior faculty members in the sciences and engineering who have shown a demonstrated commitment to research and engineering. Lilley's award is funded under the federal government's economic stimulus plan, the American Recovery and Reinvestment Act of 2009.

UIC Physicist Wins Career Award for Cobalt Oxides Study

University of Illinois at Chicago physicist Robert Klie, whose academic career started with study of astronomical phenomena light-years away, but circled back to earthly materials science at the atomic level, has been awarded a five-year, $400,000 National Science Foundation Faculty Early Career Development award to further his research on cobalt oxides, a promising class of ceramic materials.

"They have promise, but at this point we simply don't know how they work," said Klie, assistant professor of physics.

Cobalt oxides are a group of materials that combine cobalt and oxygen with other elements such as calcium, titanium or lanthanum. Many researchers think the thermo-electric and magneto-resistive qualities of these cheap, non-toxic and highly stable compounds could make them ideal for use in next-generation magnetic storage devices in computer hard drives, or in coatings that could be applied to automobile engine blocks and tailpipes where heat could be converted into electricity.

"We'll try to understand the mechanism of how these materials function," said Klie. "Once we understand that, we'll try to improve upon these properties and try to increase their efficiency even when made in large quantities."

At present, cobalt oxides are neither reliable nor efficient enough to be used in hard drives or as thermo-electric coatings, because scientists lack fundamental understanding at the atomic level.

Klie's NSF Career award will be used primarily to hire graduate and undergraduate assistants to carry out laboratory experiments aimed at unlocking the secrets of what makes cobalt oxides work at the atomic level, and how to scale-up production for useful application. Award money will also pay for use of UIC's scanning transmission electron microscopes and to develop a graduate-level course in materials science.

Klie's UIC collaborators are Siddhartha Ghosh, assistant professor of electrical and computer engineering, and Serdar Ogut, associate professor of physics. Other collaborators include Yale University physicist Charles Ahn and chemical engineering professor Eric Altman.

A native of Cologne, Germany, Klie studied at the Max Planck Institute for Radio Astronomy at the University of Bonn before switching his studies to biomedical imaging at Kingston University in London. He then switched to condensed matter physics while working on his doctorate at UIC, moving on to do postdoctoral work at the Brookhaven National Laboratory in New York where he held a prestigious Goldhaber Fellowship. Klie returned to UIC in 2006 to join the faculty.

"It's fascinating to look at individual atoms," said Klie. "That's what convinced me to switch to condensed matter physics. The ability to manipulate them and functionalize materials to make them perform better at the atomic level is what convinced me to stay in this field."

The Career award is the National Science Foundation's highest honor, awarded to junior faculty members in the sciences and engineering who demonstrate a commitment to research and education.