Chasiotis Scales Up to Success

The unusual nature of nanoscale structures: A polymeric nanofiber mounted on a MEMS micromachine for tensile testing. A human hair at the upper half of the images provides a familiar scale. Inset: A polymeric nanofiber with periodic surface ripples induced by stretching it with the MEMS device. Such periodic ripples are uncommon in macroscale nanofibers which form only a single ripple (neck) when extended in the same manner.
The unusual nature of nanoscale structures: A polymeric nanofiber mounted on a MEMS micromachine for tensile testing. A human hair at the upper half of the images provides a familiar scale. Inset: A polymeric nanofiber with periodic surface ripples induced by stretching it with the MEMS device. Such periodic ripples are uncommon in macroscale nanofibers which form only a single ripple (neck) when extended in the same manner.

Ioannis Chasiotis came to America from his native Greece 14 years ago and in that time has earned a Ph.D., secured faculty positions at a top flight engineering school and premier research institute, and found himself shaking hands with the President of the United States.

The approach Ioannis Chasiotis takes to materials science research is that understanding materials at their smallest scales improves applications at higher scales. Chasiotis’s professional life has reflected a similar storyline that also serves to validate his scientific approach: from humble beginnings as a newly-arrived-in-America graduate student from Greece to 14 years later standing next to the President of the United States as one of America’s top young scientists.

Since leaving his native Greece for America in 1996, Chasiotis has earned a Ph.D. in Aeronautics from Caltech, and secured faculty positions at the University of Illinois and at the Beckman Institute, where he maintains his own research group. Earlier this year, Chasiotis went to the White House along with other honorees to receive a Presidential Early Career Award for Scientists and Engineers (PECASE), the highest honor bestowed by the United States government on scientists and engineers in the early stages of their independent research careers.

Chasiotis, a member of Beckman’s Autonomous Materials Systems group, said that the award and ceremony at the White House with President Barack Obama was a special, once-in-a-lifetime event for him.

“It was quite something, especially for me coming less than 14 years ago to this country,” Chasiotis said. “Then getting to meet the President and get an award for my research, it’s beyond what I could dream. It was a major honor and it was very nice to see the President up close.”

The arc of his American success story mirrors his approach to materials science research. Chasiotis says the best method for understanding and working with materials such as polymers and their nanocomposites is to start at the nanoscale and model up; it is, he says, an approach that will lead to more effective and better designed materials for use in products and other applications.

“My research goes bottom up,” he said. “We start at the bottom of the scale and move step by step up through the scales, rather than fabricate bulk materials and then dig in to discover why they behave the way they do or don’t. If I could find out how the individual building blocks function in a material, maybe I could then be able to design materials with certain desired and unique mechanical properties at the macroscale.”

Chasiotis is a Willett Faculty Scholar of Engineering at Illinois, with appointments as an Associate Professor of Aerospace Engineering and at the Micro and Nanotechnology Laboratory in addition to Beckman. His research investigates the nanoscale mechanical behavior of hybrid materials, and hinges upon experimentation starting with the smallest sizes. The PECASE award relates to his work trying to understand the interfaces between polymeric nanomaterials. 

“That involves understanding how materials, particularly polymers, behave when we fabricate them in very small, nanoscale, volumes,” Chasiotis said. “The issue is that we don’t know what their interfaces with other materials are like, how they behave and what they should be so that they have a significant contribution to the properties of bulk scale composites.

“And these interfaces involve very small volumes of polymers. How materials behave mechanically when they are confined in small volumes is vastly unknown, especially for polymers which in many ways resemble spaghetti strands. Because of this particular structure they are not homogeneous at the nanoscale, which of course applies to all nanostructured composite materials. We would like to understand how nanoscale components interact inside bulk materials so that we improve their mechanical properties.”

The approach of Chasiotis is that working at smaller scales provides the best way to take advantage of the nanoscale properties of small volumes of materials, similar to what happens when fabrics are made from strong microfibers, or even nanofibers, giving them greater flexibility and strength, or even the ability to repel stains.   

“We find that most materials have unusual nanoscale behavior which we don’t see in the nominally same materials at larger scales,” Chasiotis said. “Very small material structures, such as polymer nanofibers that consist of numerous molecular chains, won’t behave the same in bulk form such as microscale fibers made of the same polymer. This is because nanofibers are made out of discrete blocks that are of similar sizes as the nanofiber itself.

“Some nanoscale properties of discrete building blocks are averaged out in microscale fibers but they are maintained in nanoscale fibers. So instead of combining trillions of individual polymer molecules to make bulk materials, what if we use billions of nanoscale fibers, each of them including hundreds of polymer molecules, just like we weave fabrics out of fine threads, to build hierarchical bulk materials? This is one of the objectives of my research lab: understand how the material organization could take advantage of great nanoscale properties and turn them into great macroscale properties.”

Chasiotis said research at his lab involves understanding how mixing very small quantities of hard nanomaterials, such as nanotubes or nanofibers, with polymers affects the behavior of the polymer, resulting in greater strength.

“But the majority of the material is still a polymer which, however, does not behave as pure polymer any longer,” he said. “It is still lightweight but we changed many of its other properties. The role of nano here is to modify some of the properties of existing materials without affecting the rest of their advantageous attributes.”

That work at the nanoscale is dependent on very small tools, especially the ones designed by Chasiotis’s Nanomechanics and Materials Research Laboratory (NMRL).

“This research area is challenging because we are lacking potent tools,” Chasiotis said. “We need specialized microscale tools which are based on MEMS (microelectromechanical systems) and are finer than a human hair.”

Designing tools for nanoscale research is critical to Chasiotis’s lab performing experiments with nanomaterials.

“We design and use MEMS as the tools to probe and understand how nanomaterials behave because the nanoscale is too small for existing mechanical probing tools,” he said. “We also study the behavior of materials for the fabrication of MEMS so that we improve on the durability of micro-machines and micro-tools themselves.”

The Chasiotis group works regularly with Sandia National Laboratories in New Mexico in developing tools for their research. Students from the NMRL lab have twice won competitions at Sandia for best design of MEMS tools specifically created to study nanoscale phenomena.

“We have worked with the Sandia National Labs on MEMS reliability for several years,” Chasiotis said. “They are a leader in MEMS fabrication in our country. We work with them on how they are made and how one can make them stronger, more resistant to failure, more durable.”

Students from the NMRL last took home first prizes in the competition in 2007 and 2008. Chasiotis said this competition was a unique experience for his students. 

“The best aspect of such competitions it is that they provide an opportunity and at the same time the responsibility to the students who then unleash their creativity,” he said. “I don’t tell them what to do; I try to offer only the big picture, which allows the creative students to emerge and innovate.”

Chasiotis said that creative setting is beneficial and appealing to his students.

“Scientific research cannot be timed or planned,” he said. “The longer you work on a subject the more interesting it becomes and more challenging and exciting questions emerge, which you never thought of before.”