Abstract
An experimental and theoretical study on the 3D trapping and manipulation of microbubbles by means low power laser-induced temperature gradients induced in ethanol by bulk light absorption (λ = 1550 nm) is presented. Two optical fibers were used: One for bubble generation (OFG) and the other for both trapping and manipulation (OFT). Light from a Q-switched pulsed laser (λ=532 nm & pulse width τp=5 ns) propagates in fiber OFG and gets absorbed at silver nanoparticles (AgNPs), previously photodeposed, at the distal end of a fiber optic core, generating the microbubbles. In the fiber OFT, light of low power CW laser was used to trap and manipulate the bubbles by thermocapillary induced by light bulk absorption in ethanol. The microbubble generated on OFG migrates towards the fiber OFT. The equilibrium between the buoyancy force FB, drag force FD and the Marangoni force (also known as thermocapillary force) FM gives rise to a 3D stably trapping and manipulation of the microbubble for the best time to our best knowledge.
Highlights
Trapping and manipulation of microbubbles have become a very useful tool in various applications such as manipulation of micro-objects [1, 2], fabrication of micro-valves [3, 4], photolithography [5], among others
Benerjee et al [18], reported the trapping and 2D manipulation of bubbles due themal bluming and Marangoni effect triggered by light absorption of a focused continuous wave (CW) laser on colloidal particles suspended in isopropanol
We report the 3D trapping and manipulation of a microbubble through temperature gradients generated by light absorption
Summary
Trapping and manipulation of microbubbles have become a very useful tool in various applications such as manipulation of micro-objects [1, 2], fabrication of micro-valves [3, 4], photolithography [5], among others. There are different techniques for generating, trapping, and manipulating microbubbles in liquids using thermal [6,7,8], acoustic [9, 10], and optical effects [11,12,13]. Benerjee et al [18], reported the trapping and 2D manipulation of bubbles due themal bluming and Marangoni effect triggered by light absorption of a focused CW laser on colloidal particles suspended in isopropanol. They require rather large optical powers >100 mW; besides, they did neither show steady-state trapping nor stably manipulation. Our research group has demonstrated both the generation and quasi-steadystate trapping and manipulation of single microbubbles in optical fibers using the Marangoni effect [19, 20]
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