Abstract
Micrometer-sized vapor-gas bubbles are formed due to local heating of a water suspension containing absorptive pigment particles of 100 nm diameter. The heating is performed by CW near-infrared (980 nm) laser radiation with controllable power, focused into a 100 μm spot within a 2 mm suspension layer. By changing the laser power, four regimes are realized: (1) bubble generation; (2) stable growth of the existing bubbles; (3) stationary existence of the bubbles and (4) the bubbles' shrinkage and collapse. This behavior is interpreted based on the temperature conditions. The generation and evolution of single bubbles and ensembles of bubbles with controllable sizes and numbers is demonstrated. The bubbles are grouped within the laser-illuminated region and form quasi-ordered structures. They can easily be moved and transported controlled by the focal spot. The results are useful for applications associated with the precise manipulation, sorting and specific delivery in nano- and micro-engineering problems.
Highlights
The bubble generation by CW laser radiation is more suitable for various technological purposes
Principles of the bubble generation and growth According to the known ideas [2,19,20,21], the bubble nucleation initially occurs near a single absorbing nanoparticle in conditions of water superheating when the local temperature exceeds the standard boiling temperature 100 °C
We describe a method for controllable generation of vapor-gas microbubbles and their ensembles in water suspension with absorbing nanoparticles
Summary
Gas and vapor bubbles of nano- and micrometric sizes in aqueous solutions are interesting for many fundamental and applied research problems: thermodynamic studies of liquid superheating and phase transitions in nano-scale [1,2,3,4,5,6], microhydraulic and micromachinery manipulation [7,8], microoptics [9], diverse biomedical applications including cell investigations, sorting, precise drug delivery and therapy [11,12,13]. The bubble generation by CW laser radiation is more suitable for various technological purposes In this case, a rich and intricate dynamic behavior with fluid superheating and explosive bubble formation is possible [18,19,20], but more attractive is the availability of near-stationary regimes of bubble evolution permitting their detailed investigation and control [2,21]. A rich and intricate dynamic behavior with fluid superheating and explosive bubble formation is possible [18,19,20], but more attractive is the availability of near-stationary regimes of bubble evolution permitting their detailed investigation and control [2,21] It is the near-stationary long-living bubbles that provide exclusive possibilities for the precise mass transfer, highly selective chemical actions, targeted transport of biological cells and species, creation of adjustable microoptical systems, etc [3,4,6,8,9,10,11,12,13]. Their spatial localization is fixed within the bright spot, and the bubbles can be transported across the liquid volume together with the focal region of the beam
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
