Profile of Subra Suresh

During his long and distinguished career, Subra Suresh has made crucial contributions to the field of engineering. While finishing up high school in India in the 1970s, however, Suresh was not even sure of going to college, let alone becoming an engineer. Nonetheless, Suresh decided to take a shot at the entrance examination for the prestigious Indian Institutes of Technology. “A month before my exam, I bought a book to prepare and worked through some practice questions and just thought, go try it,” Suresh says. “To my surprise, I got in.” His degree in mechanical engineering from Indian Institutes of Technology Madras would turn out to be the starting point of a wide-ranging research career.

Subra Suresh. Image credit: Nanyang Technological University, Singapore.

Suresh’s research interests would eventually span engineering, basic science, and medicine. His multidisciplinary work led to elected memberships in all three US National Academies: The National Academy of Engineering in 2002, the National Academy of Sciences in 2012, and the National Academy of Medicine in 2013.

Suresh has held several prestigious positions, from being dean of Massachusetts Institute of Technology’s School of Engineering and president of Carnegie Mellon University to leading the National Science Foundation (NSF) of the United States. Now President of Nanyang Technological University, Singapore, Suresh continues to push forward in research with his recent work on deforming nanoscale diamond. In his Inaugural Article (1), Suresh and his colleagues show computationally that it is possible to make nanoscale diamond behave like a metal with respect to select properties, which would open up a wide array of applications in microelectronics, optoelectronics, and solar energy.

Spanning Many Disciplines

After obtaining his bachelor’s degree at Indian Institutes of Technology Madras, a scholarship offer led Suresh to attend Iowa State University for a Master’s degree in mechanical engineering. When he left for the Massachusetts Institute of Technology (MIT) two years later for a doctorate, Suresh joined the materials group in mechanical engineering, beginning his foray into materials science.

After just a year and a half into his doctoral work at MIT, Suresh’s thesis committee deemed he was ready to receive a doctorate. “I was just stunned when they told me I was ready to defend my ScD [Doctor of Science] thesis,” he says. Suresh had finished so quickly that he was not yet sure about the next step. So, when his thesis advisor moved to the University of California, Berkeley, and offered him a postdoctoral fellowship, Suresh accepted.

After two years at Berkeley, Brown University offered Suresh a faculty position. “They were looking for someone to bridge mechanical engineering and materials science, and they thought I would be the right candidate for it,” says Suresh. “That's how I migrated more and more into materials science,” he says. Brown granted Suresh tenure in less than three years, and during his 10 years there Suresh worked mainly on structural materials, such as steel, aluminum, and ceramics, work that culminated in his first book, Fatigue of Materials (2).

Before long, MIT approached him, looking for a materials science professor with a background in mechanical engineering. “They made me an offer I couldn’t say no to, and so I went back to MIT as the R. P. Simmons Professor in 1993,” says Suresh. With a joint appointment in materials science and mechanical engineering, Suresh changed his research focus from large structures to small ones. He worked mainly on microelectronics and film coatings, work that led to a second book, Thin Film Materials (3).

In 2003, Suresh pivoted again, this time to biomedical sciences and engineering. “We started looking at red blood cells and the connection between mechanical properties at the cellular and molecular level, and human diseases, such as malaria and sickle cell anemia,” he says. Over the next several years, Suresh and his research group published prolifically at the intersection of engineering and physiology (4–7).

In 2010, Suresh was offered a challenge on a different scale. “President Obama nominated me to be the director of the National Science Foundation,” says Suresh. “That was a great honor when the White House called.”

Driving Innovation at the NSF

As director of the NSF, Suresh launched the Innovation Corps (I-Corps), an initiative aimed at helping researchers across the country commercialize their discoveries from basic research. “I felt that there was a lot of very good science that’s funded by NSF with taxpayer funds that could potentially lead to companies or economic value or patents, but that never sees the light of day,” he says. “I believe that any smart, young person anywhere can come up with a brilliant idea,” says Suresh. “But if you happen to be in a place where there’s no infrastructure for commercialization, no matter how good an idea you have, it doesn’t have a chance to come to fruition,” he says.

Through the I-Corps, researchers could submit a short proposal to take their existing research beyond publications. “If your proposal is accepted you’ll receive a small grant, on the order of $50,000, for a short period of time—six months to one year—to explore if your idea has any chance of going further,” says Suresh. After a year of funding, researchers could evaluate whether their idea had any chance of succeeding, in which case they could found a company or look for outside funding to take the idea further. “NSF is just a facilitator, to enable the connections and the networking,” says Suresh.

Suresh launched I-Corps in 2011 with $6 million of the NSF’s then $7 billion budget, but the initiative has since come a long way. “To my pleasant surprise, it has become one of the most successful programs now,” says Suresh. I-Corps now has an annual budget of $30 million and has funded more than 1,200 projects between 2012 and 2018 across 247 United States universities, which directly led to 577 companies. The program has spawned numerous imitators, not just at other United States agencies, such as the Department of Energy and the National Institutes of Health, but across the world, including in Ireland, Australia, and Singapore. “They all have I-Corps–like programs now,” says Suresh. “So this is one of the most satisfying things I did at the NSF,” he says.

After his stint at the NSF, Suresh became president of Carnegie Mellon University in 2013 and launched several initiatives over the next four years. These programs included the Global Learning Council to accelerate the impact of technology-enhanced learning, an ambitious infrastructure development effort, a Center for Entrepreneurship, and the Presidential Fellowships and Scholarships Program to support top students. During his tenure as president, Carnegie Mellon University’s undergraduate freshman class in the School of Computer Science comprised a record 48% of women students, three times the United States national average.

Improving the Performance of Diamonds

In 2017, Suresh was appointed president of Nanyang Technological University, Singapore. While helming a major research university, he also began research on nanoscale diamonds.

“We had a hypothesis that materials often behave surprisingly differently at the nanoscale than at the macro- or even micro-scale,” says Suresh. In addition to being the hardest material, diamond is extremely brittle. “If you try to break it, nothing will happen at first until you impose a very high load, and then all of a sudden it will crack and break catastrophically,” says Suresh. “When we go to the nanoscale, things become stronger, there is more surface area per unit volume, and the density of defects becomes smaller. So we thought nanodiamond might behave differently than bulk diamond that you can buy in a store,” says Suresh.

In a 2018 study, Suresh and his colleagues grew synthetic diamond needles tens of nanometers in diameter and a few hundred nanometers in length on a silicon surface (8). Whereas bulk diamond would typically fracture if pushed beyond a strain of ∼0.15%, the nanoneedles of diamond could be experimentally bent all of the way up to a local maximum strain of more than 9% and still return to their original shape. “To our surprise, we could actually bend the needle like you would bend a paperclip,” says Suresh. “We had to videotape the experiment to convince ourselves and others that you can actually bend diamond,” he says. Independent validation followed within a year when a group in China reproduced the results using natural diamond (9).

Bending diamond is not just a matter of intellectual curiosity. Diamond has appealing properties not only as the hardest material found in nature, but also as a semiconductor. Previous research had shown that straining silicon could improve its semiconductor properties by changing its band gap. “If we can bend a nanoscale diamond by 9%, maybe you can change the band gap by straining on demand without changing chemistry,” says Suresh. Modulating the band gap of diamond solely through mechanical means could lead to numerous practical applications in solar cells, optoelectronics, and microelectronics.

In a 2019 article (10), Suresh and his collaborators showed computationally that straining diamond could potentially change its band gap from 5.6 eV to ∼2 to 3 eV, bringing it within the range of currently used semiconductor materials, such as silicon carbide and gallium nitride. But Suresh was not content to stop there.

In his Inaugural Article (1), Suresh explored whether straining diamond could reduce its band gap down to zero, essentially making it behave like a metal. He also wondered if he could achieve this feat under strains that had already been shown experimentally and without triggering a phase change that would convert diamond into graphite. “We showed using machine learning that the answer to all of those questions is yes,” says Suresh. “Using amounts of strain that are already known to be possible experimentally, you can make the band gap of diamond vanish,” he says. The same method could be used to improve the properties and performance of most semiconductor materials with information, communication, and energy applications, says Suresh.

This work continues Suresh’s long tradition of multidisciplinary science. “This is materials science meets computer science meets mathematics and data analytics and artificial intelligence,” he says. “Interdisciplinary research has come a long way from when I first went to Brown in the 1980s, where even mechanical engineers working with materials scientists was a very big deal,” says Suresh.

For all his success across varied disciplines, Suresh cherishes his mechanical engineering roots, and one of his latest honors harkens back to those roots. Suresh is the recipient of the 2020 American Society of Mechanical Engineers (ASME) medal, the highest honor given annually to a single individual chosen from the society’s global membership of more than 100,000. He says the award brings back nostalgic memories of joining ASME as a student member, when he first came to Iowa State University in the late 1970s at the start of his illustrious career. “It’s very special to receive that from a society that I’ve been part of far more than 40 years,” he says.