Our mission is to explore various physical phenomena at liquid-solid interfaces. We use micro/nanotechnology to control the properties of solid surfaces to trigger novel interfacial phenomena.

Currently, our research topics encompasses nanofluidics, phase change phenomena (condensation and evaporation), capillarity, and surface-driven flows. We apply our research to various thermal-fluidic applications such as frictional drag reduction, anti-icing, anti-fouling, water management and energy conversion.

Micro/nano surfaces for fluidic applications

We develop micro/nanostructured surfaces tailored to specific applications such as frictional drag reduction, anti-fouling, and self-cleaning. We manufacture nanostructures on various substrates such as silicon, metal, and polymers based on nanolithography, oxidation method, and spray coatings.

 

Nanofluidics

We experimentally study transport phenomena using micro/nanofluidic platform. Particularly, we are interested in interfacially-driven water transport in presence of solute concentration difference or temperature difference. Also, we study ion transport phenomena in nanofluidic system in connection with energy harvesting and desalination.

 

Drop dynamics

We study how drop interacts with complex surfaces under dynamic conditions and attempt to control its dynamic response by tuning the surface property actively or passively. Our recent works include the reduction of contact time during impact, the understanding of frictional property on drop spreading during impact, and water penetration dynamics through the mesh during drop impact.

 

 

Phase change phenomena

We are interested in controlling phase-change phenomena, both condensation and evaporation, for various thermal applications based on micro/nanostructured surfaces. Our recent works include water harvesting via dewing, anti-frosting, enhancement of condensation heat transfer and evaporation heat transfer.

 

 

Slip on superhydrophobic surfaces

Superhydrophobic surfaces can provide a significant frictional drag reduction by inducing the effective slippage due to the trapped air layer within nano/microstructures. Currently, we are investigating frictional properties of superhydrophobic surfaces prepared by various micro/nanofabrication methods. Also, we are investigating surface-driven flows on superhydrophobic surfaces, where a significant flow enhancement was theoretically predicted.

 

 

Water management

Surfaces with special wettability can be used to manage water - e.g., moisture retrieval from air or separation of oil-water mixture - in an environmentally friendly way. For example, we separated oil and water from oil-water mixture based on a pair of superhydrophobic and superhydrophilic metal mesh membranes, while studying how geometric parameters of the membranes affect the separation efficiency and volume capacity depending on the liquid properties.

Young Su Ko, Hyeon Jeong Kim, Chi Wook Ha, and Choongyeop Lee*
Quantifying Frictional Drag Reduction Properties of Superhydrophobic Metal Oxide Nanostructures
Langmuir, 2020, Vol. 36, No. 40, pp. 11809~ 11816

Kyounghwan Song, Jaehwan Shim, Jung-Yeul Jung, Choongyeop Lee & Youngsuk Nam
Endowing antifouling properties on metal substrata by creating an artificial barrier layer based on scalable metal oxide nanostructures
Biofouling , 2020, Vol. 36, No. 0, pp. 0~ 0

Changwoo Bae, Seungtae Oh, Jeonghoon Han, Youngsuk Nam and Choongyeop Lee
Water penetration dynamics through a Janus mesh during drop impact†
Soft Matter, 2020, Vol. 16, No. 26, pp. 6072~ 6081