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. Author manuscript; available in PMC: 2017 Jun 29.
Published in final edited form as: Nano Lett. 2015 Dec 22;16(1):701–708. doi: 10.1021/acs.nanolett.5b04524

Figure 3.

Figure 3

Patterning of the PS beads on the substrate at different laser powers. (a) Optical micrographs of a series of microbubbles generated with different laser power densities: 0.56, 0.64, 0.68, 0.77, 0.83, 0.91, 0.97, 1.04, and 1.12 mW/μm2 (from small to large bubbles). (b) Dark-field optical micrographs and (c) SEM image of the series of patterned 540 nm PS beads generated with corresponding power densities in panel a. (d) High-magnification image of the 3D hollow structure formed at a laser power density of 0.97 mW/μm2. The flow velocity distribution (logarithmic scale) around a 3 μm microbubble in a cross-sectional view when (e) one layer, (f) three layers, and (g) five layers of 540 nm PS beads are trapped at the gas/liquid interface. Scale bar: (a–c) 5 μm; (d) 1 μm.