Large Effective Slip on Lubricated Surfaces Measured with Colloidal Probe AFM

Area of Science:

• Fluid dynamics
• Surface science
• Tribology

Background:

• Understanding interfacial dynamics is crucial for controlling fluid behavior.
• Lubricant-infused surfaces offer unique properties for manipulating interfacial phenomena.
• Laminar flow conditions are prevalent in microfluidic and biological systems.

Purpose of the Study:

• To investigate interfacial boundary conditions between two immiscible liquids under laminar flow.
• To quantify hydrodynamic drainage forces and effective slip length on lubricant-infused surfaces.
• To assess the potential of these surfaces for drag reduction.

Main Methods:

• Utilized atomic force microscopy (AFM) to probe hydrodynamic drainage forces.
• Employed Teflon substrates coated with silicone oil films submerged in sucrose solution.
• Measured forces as a colloid probe approached the lubricated surface.

Main Results:

• Successfully stabilized silicone oil films of several hundred nanometers thickness on Teflon.
• Determined effective slip lengths of the order of several hundred nanometers.
• Observed an increase in slip length with increasing oil film thickness and a weak increase with shear rate.

Conclusions:

• Lubricant-infused surfaces exhibit significant effective slip lengths.
• These surfaces show promise for reducing hydrodynamic drag at macroscopic scales.
• The findings have implications for designing low-drag interfaces in various applications.