No problem is too small for Nancy Sottos—in fact, the smaller the better. 

She investigates how small-scale materials behave from a mechanical sense under various circumstances.  The research looks at how processing changes properties as materials are made thinner and smaller or combined in composites, what happens at the interface between two or more materials, and how composites can be designed to perform better.  Some of the composites include smart materials.  A particular focus of research with microelectronics is on reliability. 

To work with small-scale materials—some too small to physically grab onto—Sottos has developed new and improved techniques for conducting tests and measuring mechanical responses.

With a background in experimental techniques, Sottos is well positioned for this area of science, which she described as an interface between mechanics and materials.  She found the Theoretical and Applied Mechanics (TAM) and Materials Science and Engineering Departments to be a pivotal combination when she interviewed for a TAM faculty position in 1991.

"I had an interest in mechanics and materials, but not all schools have a mechanics department, so this was an unusual opportunity," Sottos said.  "Still, it was a big step for me to come out here—my big Midwest adventure—but it turned out to be a great choice.  The students are really well trained for the type of research that I do, and there are tremendous opportunities for interdisciplinary research on this campus.  There's always a new and exciting challenge."

One focus of her work is on feroelectric thin films.  This material is used for microelectronics and MEMS applications, where small is desirable.  As materials get smaller and smaller, however, their responses and properties can change.  That change is measured with a laser-based optic technique capable of registering displacement of deformation on a picometer scale.

"It's so small it's hard to imagine," she said.  Yet this research to measure small responses, analyze microstructures, and characterize behaviors of materials can lead to big gains in the design and manufacture of more reliable products.

Sottos' newest area of research, conducted with the Beckman Institute Advanced Chemical Systems Group, is the development of autonomic materials systems that can adapt and respond as needed: heal, deform, decompose, regenerate, or react in other ways.  Her work is focused on new experimental methods to quantify autonomic response, such as the healing efficiency of a polymer, and research to gain a better understanding of the mechanics of each response.

"These smart materials are very interesting to think about from a mechanical point of view," Sottos said.  "It's important to understand how materials behave so that we can get to the application stage."

Sottos' research ties into the courses she teaches on composite materials, polymers, and the behavior of engineering materials.  One way she stays grounded in what students are thinking is by inviting one or two undergraduates to work on research projects. The experience helps students learn about research and experimental techniques while figuring out whether graduate study or a career in higher education is for them.

"I was involved in research when I was a sophomore, and that's where I began to discover what I enjoyed doing," she said.  "Now, I find it fun to work with students and see them go on to graduate school, and even if they don't wind up pursuing a research career, they benefit from working with a professor and I benefit from working with them.  They bring a fresh perspective."

Sottos also looks to colleagues for ideas and inspiration, finding that a conversation can often help her better frame her thoughts.

"A lot of ideas start out as lunchtime conversations—a group of faculty members just talking about what might be interesting or different.  I start to think about some element of the conversation a little bit more; I might work with some students to test out initial concepts; and then the idea evolves into something truly interesting," she said.  "The U of I is a great environment for that because so many talented and inspired people are here."

That process is just how Sottos, along with researchers Scott White, aerospace engineering, and Thomas Mackin, mechanical engineering, turned the idea of making composites from corn husks into a patented process.  On another project, she teamed with fellow TAM researcher Richard Weaver to investigate thin films and thin-film failure.  These films are small enough that grabbing onto them in a mechanical way is difficult.  Working from an idea described in the literature, the researchers added a new direction by applying lasers to induce stress.

Sottos' use of moiré interfermetry to measure strains and deformations by looking at the patterning of materials attracted attention from Motorola, Inc., and a grant to research factors related to reliability of mechanical and static materials used in cell phones and other electronic products.  The company was especially interested in supporting her work to set up an instructional laboratory so that students could learn the moiré technique as part of an experimental mechanics course.   Over the years, the research evolved from small-scale mechanical testing to more complex problems of dimensional stability of circuit boards.

"I like educating students and teaching them the experimental techniques that I use, and I like helping to transfer those techniques to industry and working on industry problems," she said.  "Those activities and relationships have a lot of value for me."
—Tina M. Prow