Oscar Li

oscarli@umd.edu

Glenn L. Martin Hall, College Park, MD 20742

Oscar Li is a Ph.D. student in Mechanical Engineering at the University of Maryland, College Park, supervised by Prof. Alban Sauret. His research focuses on experimental fluid dynamics, with particular interests in microfluidics, droplet dynamics, and cohesive granular flows. He combines high-speed imaging, numerical simulations, and theoretical modeling to investigate how surface properties, electric forces, and interparticle interactions influence the behavior of complex fluids and granular materials. Before joining UMD, Oscar earned an MPhys from the University of Oxford in 2026, where he conducted research in experimental quantum optics and astrophysics.

Outside the lab, Oscar enjoys playing badminton, fishing, playing the guitar, and producing music.

selected publications

Spontaneous Coulomb fissions of drops on lubricated surfaces

Marcus Lin, Peng Zhang, Aaron D Ratschow, Oscar Li, Sankara Arunachalam, and Dan Daniel

Proc. Natl. Acad. Sci. U. S. A., May 2026

Abs

Charged water drops are more widespread than commonly acknowledged. For example, raindrops typically carry charges of order [Formula: see text] pC, while routine pipetting in the laboratory produces drops with [Formula: see text] pC. Here, we show that such modest charging can spontaneously generate periodic Coulomb fissions for evaporating water drops on lubricated surfaces, with more than 60 successive cycles observed over 30 min. Interestingly, the underlying instability can be quantitatively predicted by two fissility thresholds: one marking the onset of drop elongation and another triggering fission. Each fission culminates with a fine liquid jet that disintegrates into 40 to 50 microdroplets, expelled within microseconds. The phenomenon spans an extraordinary range of length scales (from millimeters to microns) and time scales (hours to microseconds), with broad potential applications ranging from nanoscale fabrication to electrospray ionization.