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Friday, July 27, 2018

Estimation of thermocapillary force during laser trapping of confined microbubbles in a liquid

Ujitha Abeywickrema; Chenglong Zhao; Partha Banerjee

A theoretical model is introduced to determine the thermocapillary force acting on a microbubble, which adheres to the wall of a container filled with a liquid, during trapping using a focused continuous-wave (CW) laser beam. The model is developed by considering all possible forces acting on the microbubble, which also includes the optical force, the viscous force, and the friction force. The thermocapillary force, estimated from the relative velocity of the trapped microbubble with respect to the container, compares favorably with theoretical predictions based on the temperature gradient induced by the focused laser beam. The proposed experiment can be also used to determine the contact angle and/or the coefficient of friction of the microbubble at the microbubble–container interface. Our results should be useful in the design of efficient systems using microbubbles for drug delivery and water treatment systems.

DOI

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