Abstract
We developed a novel microchannel structure comprised of deep/shallow/deep three-channels. Each end of the channel was split into three, and supplying and taking of fluids to/from the channels were possible. Aqueous solution tended to fill the shallow channel because of the capillary force. Thus by introducing gas/liquid/gas from one end of the channel, stable laminar three-phase flow was formed throughout the channel. We introduced liquid/gas/liquid to the channels then. The flow became turbulent near the confluence, and settled into gas/liquid/gas laminar profile at downstream. The channel-design and flow rates were optimized to form this gas-liquid crossing flow continuously. The gas-liquid crossing flow was useful in micro-analysis and synthesis, because efficient gas-liquid contact at the turbulence promote extraction and reaction, and spontaneous separation of the two phases enabled post processes (e.g. detection). The crossing flows were also formed at the other microchannel-structures like a shallow/deep/shallow three channels and a deep/shallow two channels. A sensor for low-concentration ammonia gas by using this structure was also reported in this paper. © 2004 IEEE.