Work

Fluid Flow Measurements in Nanoslits Using Holographic Microscopy

Year: 2025

Type: article

Abstract: To understand the mechanisms driving fluid flow behavior in nanofluidics so that they may be used for on-chip biomedical and chemical applications, the fluid's motion itself needs to be observable and measurable, a difficult challenge at these small scales. We present a new method for measuring both slow and fast flows in nanofluidics using high-speed digital holographic microscopy. We measure the evaporation-driven flow in 25 and 7 nm tall nanoslit channels, showing that the consequent flow speed is about 15 times slower than open atmospheric evaporation due to the confinement of the nanoslit channel. We also measured the surface acoustic wave-driven flow in the 25 nm channel, showing flow at a speed of 0.12 m/s from acoustic wave propagation at 39.7 MHz interacting with the fluid in the channel. A process to eliminate the many sources of noise to produce these results is provided, showing that─in particular─spatial averaging is useful to determine the fluid flow and the dewetting of the fluid in the nanoslit channel over time.

Source: Langmuir

DOI: 10.1021/acs.langmuir.4c04244

Authors: Siyang Yu, Jeremy Orosco, James Friend

Institution: University of California San Diego

Language: English

Topic: Digital Holography and Microscopy

Subfield: Atomic and Molecular Physics, and Optics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,500

Funders: W. M. Keck Foundation, Office of Naval Research, Division of Electrical, Communications and Cyber Systems