Body of Work
One day your activity tracker might do a lot more than just count your steps. Someday it might measure the mechanical response of your skin, bones and blood and alert you to early changes that could signal developing health problems. This idea could be only a few years away, according to Ahmed Elbanna, CEE assistant professor in structures, who like other CEE at Illinois professors is conducting research in biomechanics, the science of studying the mechanical responses of biological materials and systems as a way to understand their condition.
The field of mechanics – a fundamental emphasis in the education of civil and environmental engineers that deals with the behavior of materials when subjected to forces – is poised to revolutionize the field of medicine. As a result, Elbanna and other CEE at Illinois researchers are finding biomedical applications for their work in mechanics, opening doors for challenging new areas of research and interdisciplinary collaboration. Their work is creating knowledge and advancing the science of mechanics for all applications, providing unique research opportunities for CEE students, and promising innovations to civil and environmental engineering through biomimicry.
Understanding bone fracture
Trained as a structural engineer, Elbanna’s work was originally in earthquake mechanics, focused on understanding fracture in quasi-brittle materials. This work provided a foundation for his work today in understanding more about bone fracture. Bone has a structure similar to geological materials, he said, with brittle mineral portions connected by interfaces of softer materials. His research is focused on understanding the mechanical responses of interfaces in bone and the effect of bone’s microstructure arrangement on the mechanical behavior. Elbanna and his team are building computational models to better understand what factors contribute to bone fractures and illuminate ways to prevent them. The results should yield benefits in both medicine and civil engineering, he said.
“If we understand better how bone fractures, we might be able to design therapeutic intervention methods that can stimulate the mechanisms that help resist the fracture, or at least design transplants and replacements that are friendlier to the bone microstructure,” Elbanna said.
Bone is also a material that engineers would like to mimic, because of the way its microstructure helps it resist fracture. A deeper understanding of bone as a material could lead to stronger building materials, Elbanna said.
“There is great interest in bio-inspiration and biomimicry, because people are discovering more and more biological materials that have remarkable properties, and we can use some of that to design new materials,” Elbanna said. “Materials and mechanics have always been part of civil engineering, it’s just that the historical focus was more on the engineering application. Now with boundaries getting lowered, people start talking with one another and realizing we can really learn from one another.”
The key is a focus on the fundamentals, he said.
“There are so many principles that are common to so many different problems,” Elbanna said. “If we understand the principles directly we can apply them, because it’s all mechanics and physics and math.”
Paying attention to the mechanical properties of biomaterials opens up a whole new way to assess health and approach treatment.
“The urge to have a more quantitative approach to biology and medicine, and also this emerging interest in connecting mechanical properties to health properties, are very intriguing,” Elbanna said. “Even the wrinkles on your skin are the result of a mechanical instability.”
Understanding fracture and healing in soft tissues
The desire to tackle challenging problems is part of what attracted Oscar Lopez-Pamies, CEE associate professor in structures, to his current work in understanding fracture and healing in soft materials. One of his research goals is to unveil the fundamentals of how failure initiates and propagates in soft matter. Up until now, much of this kind of work was focused on standard hard materials like concrete and steel, Lopez-Pamies said, so less is known about soft materials. His research is fundamental and has application in both engineering – for example, in understanding wear and tear on tires – and in medicine, in understanding damage to biological tissue.
“The modeling of soft materials mathematically is very complicated, so there are actually very nice mathematical challenges associated with it as well,” Lopez-Pamies said. “My motivation is both the mathematical challenge, as well as the fact that the applications are very interesting.”
One biomedical application for his work is in determining the severity that the presence of certain defects may have in arterial walls and whether they require surgical intervention. Another application could be in fine-tuning the standard treatment for kidney stones, which utilizes sound waves to target and break up the stones, striking the soft tissue of the kidney on the way in. Mathematical models that lead to a better understanding of the fracture of soft tissue could help doctors determine the need for, and the likely outcome of, medical interventions.
“The goal is to develop a theory that is predictive – a set of equations that will describe the system and then predict how it will behave under certain loads,” Lopez-Pamies said. “That’s very fundamental, and that’s ambitious. Can you write a set of equations that describes and predicts what will happen? If you have that, you can predict the future.”
Early prediction of malaria
Early prediction of the onset of malaria based on the mechanical response of a person’s blood cells is the focus of research by Youssef Hashash, CEE professor in geotechnical engineering. His team utilized data generated by researchers at the Massachusetts Institute of Technology (MIT), who had previously measured the mechanical properties of human blood cells as they became infected with malaria. Hashash took the MIT data set to the next level using a tool developed nearly 20 years ago by structures faculty member Jamshid Ghaboussi, now a CEE emeritus professor. Ghaboussi’s method is called an auto-progressive algorithm, a set of equations that enables researchers to determine the properties of various elements of a system by measuring the mechanical response of the system as a whole. The auto-progressive algorithm also continuously learns from laboratory and field observations. Now part of a software called selfSim and patented by the University of Illinois, the tool has been utilized in a range of applications. Hashash used it to analyze the MIT researchers’ data set, with the goal of understanding in a more fundamental way what was happening to the mechanical response of a red blood cell as it became infected with malaria. Through this work, he developed a fuller picture of the evolution of changes in the cells, with an eye toward early detection and more effective treatment.
“It is interesting to take tools that we’ve developed for civil systems – steel, concrete, soil, clays and sands – and extend them to biological material,” said Hashash. “That, to me, is a really nice link.”
A systems-based approach to medicine
Using the auto-progressive algorithm, Ghaboussi has worked with other collaborators on a range of biomechanical projects, including one with David Pecknold (MS 66, PhD 68), a CEE emeritus professor, Hashash and CEE alumnus Tae-Hyun Kwon (MS 02, PhD 06) that developed a more accurate method for testing intraocular pressure, an important step in glaucoma screening. They also determined the material properties of the cornea, allowing them to simulate eye surgeries in advance for better results. The University of Illinois has patented this method. A current project with Professor Michael Insana in Illinois’ Department of Bioengineering is working to develop an improved method of breast cancer screening involving palpation with a glove fitted with small ultrasound devices in the fingertips. The screening method will offer doctors not only breast imaging but also the quantitative properties of the observed tissues, which could offer important information about disease progression and malignancy. University of Illinois is in the process of applying for a patent for this method, as well.
A structural engineer whose area of expertise was originally in computational mechanics, Ghaboussi began working nearly 30 years ago in the area of computational intelligence, the science of modeling how natural systems work. Many things can be understood better when viewed as part of complex systems, he said. Ghaboussi and Insana have completed work on a book, “Understanding Systems: A Grand Challenge for 21st Century Engineering” that will be published in 2017. In it, they challenge engineers to apply a systems perspective to ever-broader areas.
“Complex systems are present everywhere, including buildings and our bodies and our organs and our immune system and our brains,” Ghaboussi said. “Our contribution is introducing a new way of broadening this concept of the complex system and bringing it to the field of medicine. … They’ve been studying buildings for 200 years, so we know what’s happening in a building and we can simulate it, but we don’t know how to do that for bodies because we haven‘t looked at it in that context.”
This perspective opens opportunities for engineers to contribute in completely new ways, Ghaboussi said, such as bioengineering and beyond, to a range of societal problems.
“This way of thinking doesn’t say that engineers shouldn’t be able to do what they’re doing now. It’s saying that engineers should, in addition to that, have a broader view of the systems they’re working on and how they interact,” he said. “The role of a leader is to take important steps that others are not willing to do. It’s up to departments like ours to take this very difficult step.”
Better blood-flow models
CEE Professor Arif Masud is yet another faculty member doing research in biomechanics using more sophisticated versions of computational tools initially developed for civil engineering. A structures professor with expertise in fluid mechanics, Masud’s first foray into biomechanics was in developing a new class of blood flow models. The research built on his own previous work modeling oil, which has a similar viscosity to blood. The numerical models required some adjustment, in collaboration with medical personnel, to reflect the complexity of working with biological materials.
“Biomechanics takes the principles of mechanics a notch higher,” Masud said. “You are dealing with materials which you cannot completely control. In civil engineering, we are dealing with materials like steel or concrete – material which we know will perform the same if we come back tomorrow or the day after tomorrow. Biomaterials get affected by so many different factors – patient health, dietary habits, medication – and that affects their mechanics. Here we are dealing with a material in which, on a daily basis, its response changes.”
A significant accomplishment of Masud’s team was related to heart transplant patients who received Ventricular Assist Devices (VADs), or artificial hearts. About 20 percent of these patients were reported to suffer from strokes, because of plaque build-up in a particular section of the carotid artery. Via high-performance computing on the Blue Waters supercomputer at Illinois’ National Center for Supercomputing Applications, the team determined that the lack of a pulse, which naturally functions to keep the blood from pooling and thickening into plaque, was a contributing factor. Natural hearts beat, creating a pulse; artificial hearts did not. Masud’s team also calculated how many beats per minute were required to keep the blood from coagulating. Sixty beats per second is normal, but it turned out 10 to 12 beats per minute was all that was needed to create enough hydrodynamic forces to prevent clotting. The key to figuring this out was based in the fundamentals of fluid mechanics, understanding of nonlinear material behavior, and being able to carry out massive computations on the Blue Waters platform, Masud said.
“It was because of those fundamentals that we could figure out what the underlying issue was,” Masud said. “When it comes to using mathematics and computers, I think my students are better prepared than bioengineering students who know a lot about the physiology but not what needs to be fixed in the mathematical tools.”
Masud is currently working with cardiologists at the Carle Clinic in Urbana and with surgeons at Advocate Christ Medical Center’s Center for Heart Transplant and Assist Devices in Oak Lawn, Ill.
This strong basis in the fundamentals has made CEE research applicable to a range of fields, said Masud, and an openness to interdisciplinary collaboration has helped CEE at Illinois researchers make these connections, he said.
“I became a Fellow of the American Institute of Aeronautics and the American Society of Mechanical Engineers, but I did not do anything specific especially for them for a single day in my life!” he said. “Papers I’ve written are fundamental, and then I show an application in aerospace engineering and mechanical engineering problems, and that is all. I would go and present to their conferences, but the work was hardcore method development done in civil engineering. The fundamentals have application everywhere.”
Better modeling of cell responses
This is a perspective shared by CEE Associate Professor Rosa Espinosa Marzal, an environmental engineering faculty member with research interests in nanomaterials and their effects on human health. Espinosa Marzal’s team has developed a highly accurate, mechanics-based system to physically model a human cell’s response to nanomaterials. Their goal is to determine the danger to human health of the most common nanoparticles that end up in the environment as a result of manufacturing and other industrial activities – metals, silicone particles and carbon particles.
Knowing the effect these nanoparticles have on human health is important for policymakers, she said. In addition, the team is creating fundamental knowledge about the mechanics of the surfaces of human cells, which will enable more accurate results for a wide range of research on human cells. Espinosa Marzal’s model has proven more accurate than classical model systems, because it measures the mechanical behavior of a cell surface when it interacts with a nanoparticle, taking into account deformation of the cell surface, a critical aspect. The next step is to make the model even more accurate by adding the effect of proteins on the cell surface, she said.
Why should a civil engineer work in such an area?
“The knowledge that we have in mechanics is huge compared to other disciplines,” Espinosa Marzal said. “The level of mechanics that we teach here to our students is a high level. [To work in biomechanics] you need collaborations with someone on the biological side. These systems are more challenging, but from the mechanics point of view, nobody could beat us.”
As plans coalesce for a new engineering-focused medical college on the Urbana-Champaign campus, CEE professors working in biomechanics are hoping to find even more opportunities for interdisciplinary collaboration.
For a while, Masud said, he downplayed his work in biomechanics because it wasn’t traditional work for a structural engineering professor, but a conversation with Robert H. Dodds Jr., head of CEE at Illinois when Masud joined the faculty in 2006, encouraged him to continue.
“Bob Dodds said, ‘This is going to be the new face of civil engineering,’” Masud said.