Laser-Induced Trapping of Microbubbles within the Bulk Solution

The generation and manipulation of microbubbles on surfaces have been much more ubiquitous than those in the bulk liquid. In this paper, we report the generation and trapping of microbubbles at the laser boundary in the bulk of water. In a plasmonic suspension, the light intensity-induced temperature gradient leads to a Marangoni flow that can trap the microbubble. The trapped microbubble can be directed by the light to move in water at speeds at least as high as 0.9 mm/s. These findings can potentially extend the boundary of bubble applications from surfaces toward the bulk of the liquid and open intriguing possibilities in fields like drug delivery and nano/microfabrication, among others.