Patent ID: 7138062

Claim:
A method for separating the components of a fluid sample, comprising: (a) providing the microfluidic device comprising a substrate having a microchannel formed in a surface thereof; a cover plate arranged over the substrate surface, the cover plate in combination with the microchannel defining a separation conduit for separating the components of the fluid sample according to a specific component property, wherein the separation conduit has an inlet port and an outlet port; and an integrated gradient-generation means for generating a gradient of a selected mobile-phase component in a mobile phase by the use of pressure driven flow, including a mechanical switching structure adapted to allow the mobile phase from the gradient-generation means to be transported through the inlet port into the separation conduit and out of the outlet port; (b) using the integrated gradient-generation means to generate a gradient of the selected mobile-phase component in the mobile phase, (c) controllably introducing a predetermined volume of the fluid sample from a sample source into the separation conduit; and (d) conveying the fluid sample through the separation conduit using a mobile phase, thereby separating the components of the fluid sample.