Impact of flow feedback on bubble generation in T-junction microchannels under pressure-driven condition

Under pressure-driven conditions of gas, the bubble size was experimentally studied in different types of T-junction microchannels having widths of 300 μm and heights of 100 μm. The bubble length increases with the flow rate, and we observed that it also increased with the driving pressure. This was proved through the published formulas for the bubble flow pressure difference using the experimental results. Three types of downstream channels—normal, movable, and deformed walls (of different lengths)—were used to study emerging bubbles, and a nonlinear relationship was observed between them. The channel type directly influenced the bubble size by affecting the resistance of the channel with bubbles. Furthermore, the difference between the resistances of a normal channel and a deformed channel with the same typical dimension was determined using a comparator structure between two parallel channels to evaluate the effect of flow resistance on bubble generation. The adjustment of the flow rate at downstream will give feedback to the bubble generation in the double T-junction channel.