As an engineer, Haneesh Kesari takes his inspiration from nature.
The new assistant professor of engineering marvels at how nature takes a few proteins and a bit of calcium or silica and creates structures with amazing material properties — emergent properties that might seem impossible given limited raw ingredients.
Assistant Professor of Engineering
Credit: Frank Mullin/Brown University
Kesari is currently studying Euplectella, a genus of sea sponges. Sea creatures might seem strange territory for a materials scientist, but Euplectella have peculiarities that make them something of an engineering marvel. Whereas most animal species form their skeletons with calcium, Euplectella are made mostly of silica—glass. But don’t think of these creatures as the fragile Ming vases of the sea. On the contrary, their skeletons are strikingly robust.
Kesari is interested specifically in the root-like appendages that fix the animals to the ocean floor. The glassy structures, called basalia spicules, have properties similar to man-made fiber optic cable, only the sponge-made versions are substantially stronger and more flexible. Imaging these appendages at the nanoscale reveals an intricate construction. Each spicule is made of concentric layers, some made of glass, others made of a polymer. It’s the pattern in which these layers are arranged that caught Kesari’s attention.
“You see it and think, ‘Is this really an animal skeleton or is it a figure from a math book?’” he said. “It had an algorithmic beauty to it. We didn’t know what the algorithm was, but felt that there had to be one, because it had such regularity to it.”
Kesari thought this pattern might contribute to the spicules’ renowned strength, so he set to work calculating what pattern of layers would be the strongest given the materials in the spicule. “We calculated it and it so happens the resulting algorithm matches very well with what we see in the spicule,” he said.
Amazing what nature can accomplish given enough time.
Understanding these sorts of mathematical regularities in nature could lead to the man-made materials of the future. It’s a slow and difficult process, Kesari says, but Brown is the perfect place for that sort of research. There’s a culture in the School of Engineering that “encourages the pursuit of rigor and thoroughness, and rewards originality and creativity,” he says. “It’s nice to see the traditional quality of science — the main reason why many of us chose to do science in the first place — is retained here.”
Not to mention, he adds, that Brown is known for employing many of the “rock stars” in the field of solid mechanics over the years.
Aside from his work on Euplectella, Kesari has worked extensively on understanding adhesive properties and surface roughness, including a theoretical basis for why things like sticky notes and packing tape stick better when you push them down harder. He also studies failure patterns in polymer-based materials.
Kesari earned his Ph.D. from Stanford in 2011. He grew up in southern India, where his fascination with engineering started.
“My father worked in irrigation,” he said. “One of the early experiences I had was going to these small irrigation canals to play. The entire community revolved around water for crops and everything else, and I could see how just having a simple stone structure changed people’s lives so dramatically.”
He came to view engineering as humanity’s way of putting our collective foot down, no longer helpless against the blind whims of droughts and floods.
“Engineering, it seems to me, is a very special enterprise,” he said. Through it “we control our own destiny.”
- Kevin Stacey/Brown University