Surface Bubble Dynamics in Plasmonic Nanoparticle Suspension

TL;DR

This paper investigates the growth and movement of microbubbles generated by plasmonic nanoparticles in suspension, revealing faster growth due to volumetric heating and high-speed movement driven by contact line depinning.

Contribution

It provides new insights into the dynamics of plasmonic microbubbles in nanoparticle suspensions, highlighting volumetric heating effects and the mechanism of bubble movement via contact line depinning.

Findings

Faster bubble growth rates in nanoparticle suspensions compared to pure water.

Volumetric heating around bubbles explains the increased growth rate.

Surface bubbles can be moved at speeds exceeding 1.8 mm/s through laser-induced contact line depinning.

Abstract

Understanding the dynamics of the micro-sized surface bubbles produced by plasmonic heating can benefit a wide range of applications like microfluidics, catalysis, micro-patterning and photo-thermal energy conversion. Usually, surface plasmonic bubbles are generated on plasmonic nano-structures pre-deposited on the surface subject to laser heating. In our studies, we have investigated the growth dynamics and movement mechanism of surface microbubbles generated in plasmonic nanoparticle (NP) suspension. In the first section, we observe much faster bubble growth rates compared to those in pure water with surface plasmonic structures. Our analyses show that the volumetric heating effect around the surface bubble due to the existence of NPs in the suspension is the key to explain this difference. In the second section, we demonstrate that surface bubbles on a solid surface are directed by a laser to move at high speeds (> 1.8 mm/s), and we elucidate the mechanism to be the de-pinning of the three-phase contact line (TPCL) by rapid plasmonic heating of NPs deposited in-situ during bubble movement.