Separation structure

Abstract

A centrifugal-based microfluidic device (1) that comprises a hydrophilic microchannel structure (2) in which there is aA) a separation microcavity I (4) that comprises i) a liquid inlet I (5), and ii) a liquid outlet I (6) that is at a level below the level of liquid inlet I (5) and above the level of the bottom (8) of the microcavity (4) thereby defining a lower part (4b) and an upper part (4a) of the microcavity (4), andB) a microconduit I (17) that has an inlet end I (16) directly connected to liquid outlet I (6), and an outlet end I (18) that is at a lower level than inlet end I (6).A capillary valve I (24) is associated with microconduit I (17). The flow direction through liquid outlet I (6) is directed upwards and / or liquid outlet I (6) is placed in a downwardly turned part of an inner wall of the separation microcavity (4), and / or the part of microconduit I (17) next to liquid outlet I (6) is directed upwards.

Description

[0001]The present application is a continuation-in-part application that claims priority to PCT / SE2006 / 000454, filed Apr. 13, 2006, which claims priority to U.S. Provisional Patent Application 60 / 671,304, filed Apr. 14, 2005, and claims priority to U.S. Provisional Patent Application 60 / 672,822, filed Apr. 19, 2005, and claims priority to Swedish Application No. 0501751-2, filed Jul. 29, 2005, all of which applications are incorporated by reference herein in their entirety.TECHNICAL FIELD[0002]The present invention relates to a microfluidic device in which there are one or more hydrophilic microchannel structures each of which comprises one or more of the innovative microfluidic functionalities or units presented herein, and to fluidic methods or operations utilizing these functionalities or units.[0003]A microfluidic device of the invention has one or more microchannel structures which each comprises at least one or more of the functional units of the invention:[0004]A. Capillary v...

AI Technical Summary

Benefits of technology

[0024]We have managed to lower these risks by placing valve I in a microconduit I that has an inlet end at a higher level than its outlet end in combination with designing the microconduit to support formation of a liquid plug that extends continuously downstream from valve I to a liquid front that is within microconduit I and at a lower level than the inlet end. The creation of a positive plug height between the liquid front and the inlet end will support and facilitate downstream transport of liquid. As a consequence the spin speed for transport of liquid from an upstream microcavity I having a liquid outlet I connected to the inlet end of microconduit I can be reduced with a concomitant reduction of the risk for undesired flow through of a valve (=valve II) or a downstream porous bed.

[0204]Due to the hydrophilicity of the microconduit (self-section) the driving force can be decreased after passage of each individual capillary valve, i.e. one can rely partly or wholly on capillary transport (passive) between the valves.

Problems solved by technology

Conventional embossing, injection moulding etc and other replication techniques thus seem insufficient for the manufacture of microfluidic valves based on a change in cross-sectional dimension.

Collection of liquid at valve II will mean that a liquid plug height will be built up which in turn means that the risk for the liquid to leak through valve II will increase while liquid is being collected at this valve.

Unit C: Technical problems and / or advantages: We have recognized that creation of a liquid plug in a downwardly directed hydrophilic microconduit after liquid has passed a capillary valve in the microconduit is associated with problems.

Finger valves as defined for unit C may be particular prone to clogging.

Lowering of the amount of particles in liquids initially containing suspended particles typically requires high g-forces / spin speeds and high risks for malfunctioning of valves and other through-flow functional units that might be present downstream a separation unit in a microfluidic device.

In conventional types of microfluidic detection microcavities this kind of design typically means a significant risk for the incoming solution to mix with the liquid that preoccupies the detection microcavity.

This adverse effect has in particular been found disturbing in centrifugal based systems.

Mixing at this stage is not desirable because it will lower the concentrations of the entities to be detected / measured.