Abstract
In this study, we report conditions of formation of parallel two-phase flow in a 100 nm-sized nanochannel, and revealed that properties of two-phase flow in nanochannels are different from those in microchannels, due to unique water properties by dominant surface effects in 100 nm spaces. From the results, the Capillary numbers Ca (viscous force/interfacial tension) to form the parallel two-phase flow were determined. The knowledge obtained in this study greatly contributes to achievements of chemical operations in femto-liter volumes (extended-nano unit operations: ENUO), integration of chemical processing in nanofluidic devices, and novel applications such as single cell/single molecule analysis.