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Interferometric technique for nanoscale dynamics of fluid drops on arbitrary substrates

Authors :
Gopal Verma
Kamal P. Singh
Mrityunjay Pandey
Source :
Journal of Applied Physics. 118:035306
Publication Year :
2015
Publisher :
AIP Publishing, 2015.

Abstract

We demonstrate a simple interferometric probe to detect nanoscale dynamics of sessile fluid drops on arbitrary rough or flexible substrates. The technique relies on producing high-contrast Newton-ring like dynamical fringes by interference between a weak Fresnel reflection from the air-fluid interface of the drop and an air-glass interface of a convex lens placed above the drop in quasi-normal geometry. By analyzing the dynamical fringes, we observed 100–700 nm/s fluctuations in water drops evaporating on metal, leaves, insect wing, and sand paper due to their surface roughness. Similar fluctuations were also observed during spreading of non-volatile glycerin drops on various rough surfaces. Another application of the technique is demonstrated in precision measurement of change in evaporation rate of a water drop due to cooling of a metal substrate. This technique can be further miniaturized with a microscope objective with potential for wide applications.

Details

ISSN :
10897550 and 00218979
Volume :
118
Database :
OpenAIRE
Journal :
Journal of Applied Physics
Accession number :
edsair.doi...........b0deca07ebb92ccafe9eea9c3667e1d0