Microfluidic system including a virtual wall fluid interface port for interfacing fluids with the microfluidic system

Abstract

A fluid interface port in a microfluidic system and a method of forming the fluid interface port is provided. The fluid interface port comprises an opening formed in the side wall of a microchannel sized and dimensioned to form a virtual wall when the microchannel is filled with a first liquid. The fluid interface port is utilized to fill the microchannel with a first liquid, to introduce a second liquid into the first liquid and to eject fluid from the microchannel.

Description

REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 10 / 028,852, filed Dec. 21, 2001, which claims priority to U.S. Provisional Patent Application No. 60 / 299,515 filed Jun. 20, 2001, and is related to Attorney Docket No. CVZ-OOlb, entitled “Microfluidic System Including a Virtual Wall Fluid Interface Port for Interfacing Fluids with the Microfluidic System”, filed herewith; Attorney Docket No. CVZ-001c, entitled “Microfluidic System Including a Virtual Wall Fluid Interface Port for Interfacing Fluids with the Microfluidic System”, filed herewith; Attorney Docket No. CVZ-002, entitled “Microfabricated Two-Pin Liquid Sample Dispensing System”, filed herewith; Attorney Docket No. CVZ-003, entitled “Small Molecule Substrate Based Enzyme Activity Assays”, filed herewith; and Attorney Docket No. CVZ-005, entitled “Droplet Dispensing System”, filed herewith. The contents of the foregoing patent applications are herein incorporated ...

AI Technical Summary

Benefits of technology

[0024] The present invention provides methods, devices and systems for interfacing fluids in microfluidic systems. A fluid interface port for directly interfacing a microfluidic channel network and the surrounding environment is provided in a microchannel in a microfluidic system by forming an opening in a sidewall of the microchannel. The aperture forms a virtual wall when

Problems solved by technology

Another example of the efficiency of microfluidic systems is the mixing of dissolved species in a liquid, a process that is also diffusion limited.

In conventional microfluidic systems, the structures and methods used to introduce samples and other fluids into microfluidic substrates limit the capabilities of the microfluidic systems.

The total number of samples and other fluids that can be processed on a microfluidic substrate is currently limited by the size and/or the number of reservoirs through which these fluids are introduced to the microfluidic system.

A disadvantage of known structures and methods for introducing fluids into a microfluidic system is the use and transfer of a much greater volume of fluid than is needed for microfluidic analysis due to significant size inefficiencies and sample loss.

Furthermore, with conventional methods of introducing fluids into microfluidic systems, it is difficult to control the amount of sample introduces that is eventually introduces into the microchannel after passing through a sample channel or a reservoir.

A major disadvantage of this approach for fluidic interfacing is the complex construction and operation of these micropumps and valves.

Another disadvantage is there relatively large size and internal volume when compared to the internal volume of the microchannels.

Often there are multiple orders of magnitude between these two volumes and the resulting discrepancy renders micropumps unattractive to interface with a large number of small dimensional microchannels.

The size of the device does not allow the interfacing with a large number of microchannels, and between consecutive injections, the device needs to be cleaned, thereby considerably reducing throughput.

A disadvantage is that the precise amount of injected liquids and substances depends upon a large number of factors which are difficult to control.

It is also a disadvantage that it does not allow the efficient interfacing with a large number of different liquids as for every injection port, a separate high voltage supply is required, together with the associated liquid channels for providing a closed electrical circuit.

A disadvantage is that only a very small fraction of the applied liquid is actually introduced in the target microchannel, the bulk of the applied liquid drop remains behind in the well by capillary forces.

As a result, most of the liquid is wasted and is not available for a consecutive chemical processing step.

A low injection efficiency is disadvantageous because it indicates inefficient use of chemical substances and an increased production of waste.

Besides the complexity of the required fluidic manifolds and pressurizing system, also here a disadvantage is the inherently low injection efficiency as only a very small fraction of the applied liquid is actually used in the experiment.

One disadvantage is that if a large number of liquids need to be handled, for instance in high-throughput synthesis and screening applications, a large number of wells need to be integrated on the microfluidic device.

As the costs of microfluidic chips strongly depends on the chip s

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