People

Prof. Laurel A. Kroo launched her group in Fall 2025 in the Department of Polymer Science and Engineering. The Kroo Group works in the field of complex fluids and control theory: specifically, how to leverage flow of polymeric materials to perform computation, manufacturing and sensing. Laurel did her PhD at Stanford in mechanical engineering (doctoral advisor: Manu Prakash) and her postdoctoral work at MIT in the Non-Newtonian Fluids laboratory (postdoctoral advisor: Gareth McKinley). She is known for her prior work on low-Reynolds number transport in polymeric fluids, work on "active foam" to inform mechanical communication in embryonic tissues, and recently, for developing an analytical theory for a key vorticity correction to enable the use of a technique known as exponential shear (a 40-year old semi-abandoned method) to measure average coil-stretch mechanics in polymeric fluids via torsional rheometer. Laurel has also previously worked in industry (including Apple and NASA) and has won numerous awards and recognitions; including NSF graduate research fellow, a recipient of the Caltech Young Investigator lectureship in MCE, a UC Berkeley Rising Star awardee, and in 2024 received a top-3 best young investigator award from the Society of Rheology. Laurel enjoys spending her free time playing soccer with her lab, composing classical music, gardening, and very occasionally transiting via motorcycle.

Yoon-Je (Andy) Choi is a Ph.D. student in the Kroo Group in the Department of Polymer Science and Engineering at the University of Massachusetts, Amherst. Andy joins the Kroo group with a Masters and Bachelor degree in Chemical and Biomolecular Engineering from Sogang University in Seoul. His work focuses on bio-inspired artificial micro-swimming robots inside Newtonian and non-Newtonian fluid for biomedical applications. Besides research he likes boxing, swimming, singing and playing oboe.

Srivatsa Kumar is a Ph.D. student in the Kroo Group in the Department of Polymer Science and Engineering at the University of Massachusetts Amherst. He earned his M.S. in Materials Science and Engineering from the University of Illinois at Urbana-Champaign and his B.Tech. in Chemical Engineering from RV College of Engineering, Bangalore. Prior to beginning his doctoral studies, Kumar gained industry experience working in R&D roles focused on the scale-up of polymer, paint, and coating technologies, complementing his academic research background. His research experience spans institutions including UIUC, IIT Madras, and IISc Bangalore, with work on carbon-reinforced thermoset vitrimers composites, polyelectrolyte-based batteries, and novel desalination approaches. In the Kroo Group, Kumar is interested in developing technologies at the intersection of rheology, microscopy, and diffractive materials to create new experimental tools for probing the behavior of macromolecules in polymeric liquids. Outside of research, Kumar enjoys reading manga, photography and cooking.

Clara Middleton is a PhD student in Polymer Science and Engineering at the University of Massachusetts Amherst, co-advised between the Kroo group and the Emerick group. Clara has a Bachelors of Science degree in Chemistry from Davidson College. She is interested in mechanically-responsive polymers that can be triggered and re-programmed in strong flows, as well as novel chemical synthesis and processing techniques to produce ultra-strong materials similar to Kevlar. Clara is the recipient of the prestigious Spaulding-Smith Graduate Fellowship.

Zhaofeng (which means "a sign of harvest" in Chinese) is a PhD student in the Kroo Group in Polymer Science at UMass Amherst. Zhaofeng earned his Bachelor's degree in Theoretical and Applied Mechanics from Peking University. His research interests are in the fluid mechanics of soft matter systems, especially phenomena that arise from nonlinearity, such as flow-directed self-assemblies and instabilities. He aims to leverage theoretical and experimental tools to study these intriguing nonlinear behaviors. Outside of work, Zhaofeng enjoys music and origami. Please check out Zhaofeng’s website for more information: vector-analysis.github.io

Sara joined the Kroo group in PSE in 2025 and obtained a Bachelors in Science in Chemical Engineering from Virginia Tech. She is studying the flow mechanics of dispersed media (emulsions and foams) under hydrostatic pressure for investigation of controlled mineral precipitation as a mechanism for marine carbon sequestration. Outside of research, she enjoys hiking and reading.