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Autonomous Displacement of a Solution in a Microchannel by Another Solution Disclosure Number: IPCOM000014282D
Original Publication Date: 2001-Jun-01
Included in the Prior Art Database: 2003-Jun-19

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A method and a device for displacing a solution in a microchannel by a second solution are proposed. Capillary pressure, generated by the different parts of a microfluidic system, is used to transport liquids through the channel. A special design makes this passive microfluidic system capable of autonomously and repeatedly displacing a liquid in a microchannel with another liquid, while keeping the channel filled; with this method, several liquids can be flushed sequentially without external flow control through a microchannel to allow several chemical reactions to be executed. Present microfluidic devices and methods Passive microfluidic systems, are convenient to transport, confine liquids and process minute amounts of reagents in a short time. These devices can also offer an interface that allows addressing microfluidics by handling liquids with manual pipettes. Microfluidic networks (mFNs) can deposit distinct materials at predefined locations of a substrate at high resolution and high contrast, used for patterning of surfaces. Passive microfluidic systems in general have a limitation: a liquid loaded into the device fills all the length, because in most of the cases the volume of the microchannels is much smaller than the liquid handling capability. However, most chemical processes are composed of a suite of reactions and rinsing steps, and therefore require distinct solutions to be added and removed sequentially. This could not be performed with a passive system up to now. Active microfluidic systems with external pumping power, such as pressure, electric, heating or acoustic actuation can control several liquids sequentially. But such actuation devices or systems are usually macroscopic, sometimes need a computer, and are often cumbersome to put into practice. Acvitve microfluidic systems are therefore expensive and not practical in many cases and are only advantageous for some applications. The proposed method and device for passively displacing a liquid in a microchannel by another liquid, sequentially and autonomously are deemed to provide an improvement therein. This method can be advantageous for performing many types of chemical reactions in a microchannel. A microfluidic device suitable for this purpose is presented in fig. 1 A and B to illustrate the method. The device is composed of several "functional" parts: