title: Formation and dissolution of microbubbles on highly-ordered plasmonic nanopillar arrays.
abstract: Bubble formation from plasmonic heating of nanostructures is of great interest in many applications. In this work, we study experimentally the intrinsic effects of the number of three-dimensional plasmonic nanostructures on the dynamics of microbubbles, largely decoupled from the effects of dissolved air. The formation and dissolution of microbubbles is observed on exciting groups of 1, 4, and 9 nanopillars. Our results show that the power threshold for the bubble formation depends on the number density of the nanopillars in highly-ordered arrays. In the degassed water, both the growth rate and the maximal radius of the plasmonic microbubbles increase with an increase of the illuminated pillar number, due to the heat balance between the heat loss across the bubble and the collective heating generated from the nanopillars. Interestingly, our results show that the bubble dissolution is affected by the spatial arrangement of the underlying nanopillars, due to the pinning effect on the bubble boundary. The bubbles on nanopillar arrays dissolve in a jumping mode with step-wise features on the dissolution curves, prior to a smooth dissolution phase for the bubble pinned by a single pillar. The insight from this work may facilitate the design of nanostructures for efficient energy conversion.
authors.affiliation: School of Mechatronic Engineering, China University of Mining and Technology, Xuzhou, 221116, China.|Physics of Fluids Group, Faculty of Science and Technology, University of Twente, Enschede, 7500 AE, The Netherlands.
authors.forename: Xiumei
authors.initials: X
authors.lastname: Liu
authors.affiliation: Softer Matter and Interfaces Group, School of Civil, Environmental and Chemical Engineering, RMIT University, Melbourne, VIC 3001, Australia.
authors.forename: Lei
authors.initials: L
authors.lastname: Bao
authors.affiliation: Istituto Italiano di Tecnologia, Genova 16163, Italy.
authors.forename: Michele
authors.initials: M
authors.lastname: Dipalo
authors.affiliation: Istituto Italiano di Tecnologia, Genova 16163, Italy.
authors.forename: Francesco
authors.initials: F
authors.lastname: De Angelis
authors.affiliation: Physics of Fluids Group, Faculty of Science and Technology, University of Twente, Enschede, 7500 AE, The Netherlands.|Softer Matter and Interfaces Group, School of Civil, Environmental and Chemical Engineering, RMIT University, Melbourne, VIC 3001, Australia.
authors.forename: Xuehua
authors.initials: X
authors.lastname: Zhang