In this paper a series of perpendicular rupturing flow routes with differing angles ranging from 30 degrees to 150 between the entrance channels were used to control the gas-liquid phase dispersed flow in T-junction microfluidic devices. Uniform gas bubble plugs were produced in consistent, two-phase flows within the channels of the microfluidic devices. Both the gas-liquid flow and the size of the gas bubbles, which ranged from 800 to 3100 mu m in length, depended on several influential factors including the flow rates, the physical properties of the liquid phase. and the angle between entrance channels. Considering these factors and the equilibrium between the shear force and interfacial tension within the microfluidic channels, an equation was derived in the form of L/w=1/2(Q(G)/Q(L) sin theta + 2/5 cot theta)1/2Ca(-1/5) relating the angle between the entrance channels of the two phases to the gas bubble plug length within the microfluidic device. The relationship allows for the prediction of gas bubble plug length in T-junction microfluidic devices employing intersection angles ranging from 30 degrees to 150 degrees and is thus potentially useful for the controllable preparation of monodisperse gas bubbles. (C) 2008 Elsevier B.V. All rights reserved.