A method for volume stabilization of single, dye-doped water microdroplets with femtoliter resolution

TL;DR

This paper presents a self-control method for stabilizing the volume of dye-doped water microdroplets on superhydrophobic surfaces using laser-induced evaporation and condensation balance, achieving nanometer precision over several minutes.

Contribution

It introduces a novel stabilization mechanism that maintains microdroplet size with nanometer accuracy by balancing condensation and laser-induced evaporation.

Findings

Microdroplet radii remained within a few nanometers over 455 seconds.

Stepwise volume changes occurred when laser excitation was intermittently blocked.

The method enables precise control of microdroplet volume for extended periods.

Abstract

A self-control mechanism that stabilizes the size of Rhodamine B-doped water microdroplets standing on a superhydrophobic surface is demonstrated. The mechanism relies on the interplay between the condensation rate that was kept constant and evaporation rate induced by laser excitation which critically depends on the size of the microdroplets. The radii of individual water microdroplets (>5 um) stayed within a few nanometers during long time periods (up to 455 seconds). By blocking the laser excitation for 500 msec, the stable volume of individual microdroplets was shown to change stepwise.