CBE Seminar: Itai Cohen (Cornell Physics)

Viscosity Metamaterials

Metamaterials are composite structures whose properties arise from a mesoscale organization of their constituents. Provided this organization occurs on scales smaller than the characteristic lengths or timescales associated with their response, it is often possible to design such materials to have properties that are otherwise impossible to achieve with conventional materials. Here, I will introduce and demonstrate a new material class– viscosity metamaterials. Such viscosity metamaterials can be used to engineer a variety of unique properties including flow rectification, as well as negative, infinite, or zero viscosities – responses that are inconceivable with conventional fluids. The high degree of control over the resulting viscosity, the ease with which they can be accessed, and the variety of exotic properties achievable by viscosity metamaterials make them attractive for uses in technologies for which control over fluid flows and their instabilities are critical, ranging from coatings to cloaking to 3D printing.

Bio:
Itai Cohen studies the physics of matter in motion. At Cornell, his research has focused on building microscopic robots, controlling the shear thickening behavior of microscopic and nanoscopic particles suspended in a fluid, exploring the mechanics of materials ranging from biological tissues to origami inspired metamaterials, discovering the aerodynamic and neuromuscular mechanisms used by insects during flapping flight, and determining how audiences at heavy metal concerts coordinate their movement. Understanding how emergent behaviors arise from the microscopic rules governing these systems remains one of the biggest challenges in physics.

Professor Cohen received his B.S. in physics from the University of California at Los Angeles, and his Ph.D. in physics from the University of Chicago. Following his graduate studies, he was a post-doctoral fellow in physics and the Division of Engineering and Applied Science at Harvard University. In 2005 he joined Cornell and is currently a professor of physics. Professor Cohen is an NSF Career grant recipient, he is a Fellow of the American Physical Society and is the recipient of the Kappa Delta Ann Doner Vaughn Award for his work on cartilage mechanics. He has served as a Feinberg and Braginsky fellow (2012) and the Rosi and Max Varon Visiting Professor at the Weizmann Institute (2021) and the van der Waals Visiting Professor at the University of Amsterdam (2022). He has published over 140 research articles, given over 300 invited seminars, colloquia and conference presentations, and co-authored the book Finding Your Research Voice: Story Telling and Theater Skills for Bringing Your Presentation to Life. His work has been covered by various outlets including the BBC, Scientific American, Forbes, NPR, and the New York Times. He also holds the Guinness world record for making the smallest walking robot.