报告摘要： In many cases, handling fluids and particles are regarded as two important but separate tasks, which are approached individually and independently by fundamentally different physical means. Here, I present strategies and methodologies on simultaneous manipulations of fluids and colloidal particles via phase change-induced liquid droplet actuations. The first topic is evaporation-triggered directional transport of asymmetrically confined droplet. When a liquid droplet is confined between two non-parallel hydrophobic surfaces with dihedral angle a, the droplet morphology under confinement will continuously evolve during evaporation, leading to the directional transport of the droplet towards the cusp. The asymmetrically confined droplet of volume V would drift towards an equilibrium location from the cusp with the lowest free energy. Its directional motion results from the consecutively decreasing , which is scaled as during evaporation. The second topic is partial Leidenfrost evaporation-assisted rapid analyte enrichment in droplet and ultrasensitive surface-enhanced Raman spectroscopy (SERS) on micro/nano-structured plasmonic surfaces. And the third topic is violent and explosive jumping of boiling droplet on hot micro-structured surfaces for deep cleaning of fouling even in surface roughness and interstices. Our findings on the intrinsic mechanisms of droplet actuations shed light on a novel approach to manipulating the confined or sessile droplet behaviors in a passive and decisive fashion.

报告人简介：Dr. Jiangtao Cheng is a Professor in the Department of Mechanical Engineering at Virginia Tech. He has published more than 80 peer reviewed papers in the fields of surface wetting and thermal-hydrodynamics. Dr. Cheng has won numerous awards in his career including five times Best Paper Awards in various international conferences and 2013 Outstanding Overseas Young Scholar Award from China NSFC. He was awarded the Junior Faculty Award by Institute for Critical Technology and Applied Science of Virginia Tech in 2016 and became elected faculty fellow of College of Engineering of Virginia Tech in 2019 and elected fellow of American Society of Mechanical Engineers (ASME) in 2021.