Abstract
Microbubble generation and manipulation in aqueous environments are techniques that have attracted considerable attention for their microfluidic and biological applications. Ultrasonic and hydrodynamic methods are commonly used to form and manipulate microbubbles, but these methods are limited by the relatively low precision of the microbubble sizes and locations. Here, we report an all-optical method for generation and manipulation of microbubbles with ~100 nm precision by using “hot spots” on a porous gold nanofilm under the illumination of near-infrared focused laser beam. The microbubble diameter ranged from 700 nm to 100 μm, with a standard deviation of 100 nm. The microbubbles were patterned into two-dimensional arrays, with an average location deviation of 90 nm. By moving the laser beam, the microbubbles could be manipulated to a desired region. This work provides a controllable way to form and manipulate microbubbles with ~100 nm precision, which is expected to have applications in optofluidic and plasmonic devices.
Highlights
Controllable formation and manipulation of microbubbles [1,2,3,4] are crucial techniques for numerous physical and biomedical applications, such as photoacoustic imaging [5,6], cancer surgery [7,8], drug delivery [9], and cell manipulation [10,11]
Differing from floating bubbles generated by ultrasonic and hydrodynamic methods, plasmonic microbubbles are attached to the substrate and possess a truncated spherical shape, making it feasible to change their sizes and locations by remote control [25]
We propose a nanometer-precision method to form and manipulate microbubbles on a porous gold (Au) nanofilm under illumination by a 1064 nm focused laser beam
Summary
Controllable formation and manipulation of microbubbles [1,2,3,4] are crucial techniques for numerous physical and biomedical applications, such as photoacoustic imaging [5,6], cancer surgery [7,8], drug delivery [9], and cell manipulation [10,11]. Differing from floating bubbles generated by ultrasonic and hydrodynamic methods, plasmonic microbubbles are attached to the substrate and possess a truncated spherical shape, making it feasible to change their sizes and locations by remote control [25]. This effect enables the microbubble to act as pump, valve, or lens in optofluidics [26,27,28,29], or to manipulate and fabricate colloidal particles with high mass transfer efficiency [30,31]. Optical manipulation and fusion of microbubbles at the interface between the nanofilm and water is achieved by scanning the laser beam
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