Abstract:Microchannel is notonly a channel for fluid flowing, but also a tool for microfluidflow control. By incorporating the characteristics and feature ofthe microchannel, microfluid driving, sampling, mixing, separatingdroplets formatting and controlling have been realized. In recentyears, most studies have been focused on the application ofsurface effects to achieve microfluid control, as thesurface-to-volume ratio is nearly millionfold increased inmicrochannel relative to that in macrochannel and the surfaceeffects are greatly increased in microfluidic flows. However, onlya few studies were carried out on controlling microfluid flows byusing microchannel structural characteristics. In order toilluminate the fact that the microchannel configuration is also aneffective way to control microfluid flow behavior, this paperdiscusses two aspects of flow control based on microchannelconfiguration. One is a special configuration of microchanels tobe used as microvalve, the other is a special microchannelconfiguration to be used for formatting and controlling tinydroplets. And thus microchannel configuration is shown to be ableto play an important part in microfluidic control.