Formation Characteristics of microbubble in a co-flowing liquid in microfluidic chip

Microbubble formation under the surroundings of co-flowing liquid (CFL) in a specially designed microfluidic chip was investigated. A new microfluidic chip utilizing several capillary tubes was fabricated to provide the co-axial flowing conditions. An experiment platform based on high-speed microscopic camera system (HSMCS) was designed and set up. The influences of nitrogen pressure and liquid flow rate on detachment distance and volume variation of target microbubble were studied experimentally. Experimental data and analysis results indicated that the detachment distance of target microbubble decreases substantially as the rate of CFL increases while it is almost independent of nitrogen pressure. Additionally, the volume growth rate of target microbubble almost keeps constant under fixed nitrogen pressure. The present study provides empirical references for studies in microbubble formation in microfluidic chips which contributes to realize the accurate controllability in diameter and size distribution of microbubble.