The Department of Chemical and Biological Engineering has awarded fifth-year graduate student Lingzhi Cai its annual SABIC Award for Best First Paper. A committee of SABIC researchers selected Cai's work based on its scientific merits and potential for impact. The award comes with a $1,500 prize.

The paper, published in October 2019 in the Proceedings of the National Academy of Sciences, details a new manufacturing technique that quickly generates precise droplets of material from a jet of fluid, finely controls the drops' size and locates them within a 3D space.

The work exploits a phenomenon known as the Rayleigh-Plateau instability, a mathematical description of droplet formation as a jet moves through some other fluid, such as air. This approach, well studied in classical contexts, had not been applied to an "open-sky" setting, according to the researchers. Their new method offers promising benefits for engineering biomedical products and a wide range of 3D printing applications.

Particularly striking is the work's deceptive simplicity, according to assistant professor Pierre-Thomas Brun, the project's principal investigator and Cai's adviser.

Cai said that elegance is what most drew him into the project. "You can beautifully describe all these complex phenomena using a small set of equations," he said. "Everything is very neat."

Cai was the first author on a second, follow-up paper published in Soft Matter in March 2020, using precise water droplets to print meticulous structures in curing soft-elastic materials. A third paper on related work is underway.

Cai joined Princeton as a Ph.D. candidate in 2016 after receiving a B.A. and M.Eng from the University of Cambridge. At Cambridge, he investigated methods to solve large optimization problems in chemical engineering. He has previously won the William R. Schowalter Travel Fund and, in 2014, the BP Prize for Outstanding Performance.