U-M materials scientist, chemical engineer elected into National Academy of Engineering

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Michigan Engineering professors Elizabeth Holm and Nicholas Kotov are among the newest members of the National Academy of Engineering—one of the highest honors bestowed on engineers in the United States.

"Elizabeth Holm and Nicholas Kotov have not only distinguished themselves as leaders in their fields, they have demonstrated the impact we can have as engineers, influencing how current and future generations of engineers solve problems and do their work," said Karen Thole, the Robert J. Vlasic Dean of Engineering at the University of Michigan College of Engineering. 

"We applaud this significant honor, and look forward to their continued thought leadership in the years to come."

Elizabeth Holm, the Richard F. and Eleanor A. Towner Professor and chair of the Department of Materials Science and Engineering, was nominated for her achievements in using computer simulations to understand the formation and effects of microstructures—microscopic cracks, pores and granules—inside materials. 

These features change the material's strength, hardness and electrical conductance, among other properties. Some microstructures are unwanted defects, while others can be strategically incorporated for specific purposes, and computer simulations help determine how to minimize the bad defects and optimize the good ones.

During her time at Sandia National Laboratories, Holm developed computational models that were used to approve a new lead-free solder material for circuit boards after lead was banned and restricted in the 1990s and early 2000s. Her team modeled the performance of the solder over the 50-year lifespan of a circuit board. Sandia ultimately approved the new solder alloy for use in electronic components—the first time a new material was approved based on information generated computationally.

Holm has more recently developed machine-learning tools that help scientists and engineers analyze microstructures when designing, manufacturing and assessing the quality of materials. Other computational tools created in her lab have enabled the materials research community to achieve the greatest understanding from the smallest amount of data, which is important in applications where data is sparse or costly.

"I had to read the email headline several times before I could believe what I saw," said Holm, about receiving word of her election. "I am deeply honored for my work to be recognized at this level, and I am immensely grateful to my colleagues and students, as science is truly a community endeavor."

Nicholas Kotov, the Irving Langmuir Distinguished University Professor and Joseph B. and Florence V. Cejka Professor of Chemical Engineering, was nominated for developing methods that allow combinations of nanoparticles, nanosheets and nanofibers with varying sizes, shapes and chemical composition to self-arrange into composite structures that mimic the properties of biological materials and can be manufactured at scale.

The resulting composite materials can have new, otherwise unobtainable properties that are greater than the sum of their parts. Kevlar-based nanofiber structures made in his lab resemble cartilage—they are strong and flexible while also being porous enough for ions to pass through. They are ideal for batteries that can store more energy and recharge faster than conventional lithium batteries. Kotov is developing these batteries at his startup, Valerion Energy. Other composite materials he is investigating could enable heat-resistant LCD screens.

Kotov has also produced chiral nanostructures, twisted at micro- or nanoscales, that self-assemble into bioinspired materials. He and his team are using them to generate and detect circularly and elliptically polarized light. Many biological molecules and medicines are chiral, so structures like these show promise for medical diagnosis, pharmaceutical production and quality control. They may also enable computer-vision tools to identify objects and their microstructures based on the polarized light that they naturally emit.

"I feel inspired by this decision to do more," Kotov said. "This is a huge honor, but I don't want to rest on my laurels. I feel like I'm just getting started and that I can help more people. That's my job as a member of this special group of colleagues who represent both intellectual excellence and worldwide impact."

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