The measurement of Navier slip on individual nanoparticles in liquid

TL;DR

This paper introduces a novel experimental method to measure the Navier slip length on individual nanoparticles in liquid with sub-nanometer accuracy, revealing size-independent slip lengths around 2.7 nm, thus enabling validation of molecular simulations.

Contribution

It presents a new technique for precise measurement of slip length on single nanoparticles, overcoming previous size and sensitivity limitations.

Findings

Measured slip length of 2.7 nm on gold nanoparticles

Slip length is independent of particle size

Method enables validation of molecular simulation data

Abstract

The Navier slip condition describes the motion of a liquid, relative to a neighboring solid surface, with its characteristic Navier slip length being a constitutive property of the solid-liquid interface. Measurement of this slip length is complicated by its small magnitude, expected in the nanometer range based on molecular simulations. Here, we report an experimental technique that interrogates the Navier slip length on individual nanoparticles immersed in liquid, with sub-nanometer precision. Proof-of-principle experiments on individual, citrate-stabilized, gold nanoparticles in water give a constant slip length of 2.7$\pm$0.6 nm (95% C.I.) - independent of particle size. Achieving this feature of size independence is central to any measurement of this constitutive property, which is facilitated through the use of individual particles of varying radii. This demonstration motivates studies that can now validate the wealth of existing molecular simulation data on slip.