Optofluidic debubbling via a negative optical gradient force

Abstract

This Letter describes the generation and removal of air bubbles from a fluid using an optofluidic platform. A T-junction geometry was used to generate air bubbles, and a negative optical gradient force subsequently removed the generated bubbles from the main stream. A numerical analysis was performed to predict and interpret the system performance. The optical gradient force was calculated using geometric optics models. A modified viscous drag force was applied when the bubble size was comparable to the channel's geometric dimensions. The Dulbecco's phosphate buffered saline and air flow rates were adjusted to control the air bubble size and bubble generation frequency. Despite displaying a substantial increase in the viscous drag force as the bubble size approached the channel dimensions, the bubbles could be readily removed from the main fluid stream under appropriate optofluidic circumstances.