Apparatus and method for trapping bead based reagents within microfluidic analysis systems

Abstract

An on-chip packed reactor bed design is disclosed that allows for an effective exchange of packing materials such as beads at a miniaturized level. Also disclosed is a method of treating a sample within a microfluidic analysis system, comprising: providing a main channel having a trapping zone; providing a slurry of a reagent treated packing material; inducing a flow of said packing material into said trapping zone through a flow channel connected to said trapping zone to load said trapping zone and form a packed bed of said packing material; and flowing a sample containing analytes through said packed bed, said reagent treating the sample. The present invention extends the function of microfluidic analysis systems to new applications including on-chip solid phase extraction (SPE) and on-chip capillary electrochromatography (CEC). The design can be further extended to include integrated packed bed immuno- or enzyme reactors.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This is a continuation of application Ser. No. 10 / 148,425 filed Nov. 4, 2002.FIELD OF THE INVENTION[0002]The present invention relates generally to microfluidic analysis systems, and more specifically to micro-Total Analysis Systems (μ-TAS), for performing liquid phase analysis at a miniaturized level.BACKGROUND INFORMATION[0003]Recent developments in the field of micro-Total Analysis Systems (μ-TAS) have led to systems that perform chemical reactions, separation and detection at a miniaturized level on a single microchip [see, for example, Harrison, D. J.; Fluri, K.; Seiler, K.; Fan, Z.; Effenhauser, C. S.; and Manz, A., Science 1993, 261, 895-897. Harrison, D. J.; and van den Berg, E.; Eds., Micro Total Analysis Systems '98, Proceedings of the μTAS '98 Workshop (Kluwer: Dordrecht, 1998). Coyler, C. L.; Tang, T.; Chiem, N.; and Harrison, D. J., Electrophoresis 1997, 18, 1733-1741].[0004]Most prior art microfluidic devices are based on co...

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Benefits of technology

[0029]In another embodiment, the method further includes the step of providing a hook structure at the connection point between said flow channel and said trapping zone, so as to prevent direct line-of-sight entry of said packing material, thereby to promote even packing.

Problems solved by technology

While the functionality of these devices has continued to increase, one key feature that is presently lacking in these prior art devices is the ability to effectively incorporate on-chip packed reactor beds, for introduction of packing materials with immobilized reagents or stationary phases.

While a few attempts have been made to employ packed reactor beds in some prior art designs, the difficulty of packing portions of a complex microfluidic manifold with packing material (such as microscopic beads) has so far hindered the effective utilization of these reagent delivery vehicles within microfluidic devices.

However, the packing material in this prior art design could not be readily packed or exchanged, thus limiting its utility.

Current construction methods do not produce high yields of useable frits.

Furthermore, using frits produced by prior art methods of construction often leads to the formation of undesirable bubbles.

Bubbles cause discontinuity within a column, hindering solution flow and ultimately preventing separation from occurring.

The formation of bubbles, which have been observed to increase at higher voltages, also limits the amount of voltage that can be applied across the capillary, thereby limiting column length, separation efficiency, and speed of analysis.

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