JP2005211708A - Liquid-liquid extraction apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase an extraction speed at the interface of a microflow channel. <P>SOLUTION: A solution A being a liquid to be extracted containing a solute to be extracted and a solution B becoming a solvent for extracting the solute are supplied to the microflow channel 2 by the pumps 4 and 6 of a liquid feed mechanism, and the solution A and the solution B are brought into contact with each other at the interface thereof in the microflow channel 2 to flow as a laminar stream. A pair of electrodes 12a and 12b are arranged to a side surface on the side of the solution B of the microflow channel 2 along the flow direction of both solutions and an electric line 16 of force is generated by applying AC voltage across both electrodes 12a and 12b from an AC power supply 14 to produce an electric field gradient in the solutions A and B by the electric line of force. The solute 8 is polarized by the electric field thereof and subjected to dielectric migration by the electric field gradient to be enhanced in its concentration at the interface 10 and the extraction speed at the interface 10 is increased. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an apparatus for extracting a substance in a micro solution, for example, a microorganism, a protein, a nucleic acid, a carbohydrate, an antigen, an antibody or a mixture in which these are bound, in order to perform a chemical reaction or analysis.

  When a chemical process or apparatus is performed at a micro size, the specific interface area is large, so that the efficiency of a phenomenon occurring at the liquid-liquid interface increases. Due to the fluid dynamics, the liquid flowing through the microchannel has a small flow path, so the Reynolds number is small, and two layers parallel to the flow direction are formed.

  For example, when extraction is performed between two liquids such as water and phenol that are not mixed, the two-layer structure with a normal size is disadvantageous because the interfacial area is small, but if the space size is small, the diffusion distance becomes short. Since the specific interfacial area is also large, it is possible to perform mixed extraction only by molecular diffusion without the need for mechanical mixing. These reaction times are determined by the shape and flow rate of the site where the liquid is mixed.

An outline of a conventional extraction device using a microchannel is shown in FIG. 6 (see Non-Patent Document 1).
Solution A, which is a solution to be extracted containing the solute to be extracted, and solution B, which is a solvent for extracting the solute, are supplied to the microchannel 2 by the pumps 4 and 6 of the liquid feeding mechanism. A and the solution B come into contact with each other at the interface and flow as a laminar flow, and are branched into the flow paths of the respective layers on the downstream side and discharged. The substance A is dissolved in the solution A as the solute 8 to be extracted, and the solute 8 moves from the solution A to B by diffusion at the interface 10 between the two solutions A and B.
“Material Integration”, Vol. 15, no. 2, P.I. 3-8 (2002)

Since the extraction speed of liquid-liquid extraction between two laminar flows flowing in contact with each other at the interface of such a microchannel is determined by diffusion, there is a limit to improving the reaction speed.
Therefore, the present invention aims to increase the extraction speed at the interface of the microchannel.

The reaction time is determined by the shape and flow rate of the region where the interface between the two liquids is formed, and in the region where the interface is formed, a non-uniform electric field is applied in the solution to cause dielectrophoresis to increase the extraction speed.
That is, the liquid-liquid extraction apparatus of the present invention includes a micro-flow path in which a solution to be extracted containing a solute to be extracted and a solvent for extracting the solute are in contact with each other and flow in a laminar flow, and the flow path An electric field applying mechanism for supplying an electric field gradient that dielectrophores the solute in the extraction solution in the direction of the interface in the flow path. It is provided with.
The microchannel means a channel having a minute size that allows two laminar flows parallel to the flow direction to flow in contact with each other at the interface.

  An electric field gradient in which an electrode is placed in a region where the interface between the solution to be extracted and the extraction solvent in such a microchannel is formed and alternating current is applied, and the electric field increases from the solution to be extracted side to the extraction solvent side. Dielectrophoresis occurs when. That is, due to the electric field gradient, if the neutral particles as the solute are particles that are more easily polarized than the medium, polarization occurs in the solute and moves in the direction of the resultant force applied to the positive and negative charges. In this way, solutes that are easily polarized move through the solution and are concentrated to the interface. As a result, the reaction time of the solute at the interface is shortened.

  In the present invention, such microchannels can be arranged in multiple stages to perform extraction in multiple stages. In that case, one or a plurality of stages of micro-channels are arranged downstream of the first-stage micro-channels, and the downstream micro-channels are the solvent extracted from the solute in the immediately preceding micro-channel. The other solvent comes into contact with each other at the interface and flows in a laminar flow. The liquid feeding mechanism for supplying the other solvent, and the solute in the solvent from the previous stage where the solute is extracted are used as the other solvent. And an electric field applying mechanism for applying an electric field gradient that causes dielectrophoresis in the interface direction with the.

  In the liquid-liquid extraction apparatus of the present invention, an electric field gradient is applied to the microchannel so as to cause dielectrophoresis in the interface direction, so that extraction can be performed at high speed for a solute having polarization characteristics.

FIG. 1 schematically represents an embodiment. Compared with the configuration of FIG. 6, the configurations of the microchannel 2 and the pumps 4 and 6 that supply the solution are the same, and the solution A that is an extraction solution containing the extracted solute, and the solvent that extracts the solute, The solution B is supplied to the micro flow path 2 by the pumps 4 and 6 of the liquid feeding mechanism. In the micro flow path 2, the solution A and the solution B are in contact with each other at the interface and flow in a laminar flow. It is branched into the flow path of the layer and discharged. The substance A is dissolved in the solution A as the solute 8 to be extracted, and the solute 8 moves from the solution A to B by diffusion at the interface 10 between the two solutions A and B.
The microchannel 2 is formed in a substrate such as glass, silicon, or plastic, and has a width W of 1-1000 μm and a depth of 1-1000 μm.

  In the microchannel 2, a pair of electrodes 12a and 12b are arranged along the flow direction on the side surface on the solution B side, and an electric force is applied by applying an AC voltage from the AC power source 14 between the electrodes 12a and 12b. A line 16 is generated, and an electric field gradient is generated in the solutions A and B by the electric lines of force. The electrodes 12a and 12b are arranged on the side surface of the solution B side from which the solute 8 is to be extracted. Since the electric field gradient increases as it approaches the electrode electrodes 12a and 12b, an electric field gradient is formed in a direction that increases from the solution A toward the B direction.

  As the vicinity of the interface 10 is enlarged and shown in FIG. 2, the solute 8 is polarized by the electric field and dielectrophoresed by the electric field gradient. As a result, the polarized solute 8 is extracted by moving the solution A in the direction of the interface 10 due to the electric field gradient, increasing the concentration of the solute 8 at the interface 10, reacting with the solution B at the interface 10, and moving to the solution B side. The In the present invention, the extraction at the interface 10 includes not only the case where the chemical reaction between the solute 8 and the solution B is involved, but also the case where the extraction is performed by physical diffusion alone without the chemical reaction. It is called.

  FIG. 3 shows a second embodiment, in which the same micro flow path as shown in FIG. 1 is arranged in two stages on the upstream side and the lower stage side. The upstream microchannel 2 is the one shown in FIG. The solution B obtained by extracting the solute 8 from the solution A in the microchannel 2 is guided to the microchannel 20 on the downstream side.

  The microchannel 20 is also a microchannel having the same shape and size as the microchannel 2. In the microchannel 20, the solvent B is supplied as an extraction solvent by the pump 22 in addition to the solution B, so that the solution B and the solvent C flow in a laminar flow while contacting each other at the interface 24. In the microchannel 20, electrodes 26 a and 26 b for causing dielectrophoresis are disposed on the side surface on the solvent C side along the channel. Electric force lines 30 are generated by applying a voltage from the AC power supply 28 to the electrodes 26a and 26b, and the solute 8 is polarized by the electric force lines 30 as described in the embodiment of FIG. Dielectric migration is performed in 24 directions, the reaction time at the interface 24 is shortened, and the solution B is extracted.

  In FIG. 3, the solution A shows the case where the substance B indicated by reference numeral 8b coexists in addition to the substance A indicated by reference numeral 8 as a solute. The substances A and B have different degrees of polarization, the substance A is easily polarized, and the substance B is difficult to polarize. The substance B which is not easily polarized is not easily subjected to dielectrophoresis, and therefore, the extraction at the interface 10 in the microchannel 2 is difficult to occur. Therefore, in the microchannel 2, only the substance A can be extracted into the solution B from the solution A containing two kinds of substances A and B as solutes, and the solute 8 in the extraction solution B is extracted in the microchannel 20 on the downstream side. Furthermore, by extracting to the solution medium C, the purity of the substance A in the solvent C flowing out from the microchannel 20 is increased. Thus, even when a plurality of types of substances coexist, they can be separated according to the polarization characteristics.

In the present invention, the microchannel is configured inside the substrate. The microchannel can be formed inside the substrate by a microfabrication technique.
A more specific embodiment will be described together with a method of forming the microchannel inside the substrate.

FIG. 4 shows a method of manufacturing the liquid-liquid extraction apparatus of this embodiment. The left side views of (A) to (E) are plan views, and the right side view is a right side view.
(A) A photoresist 42 is applied to one surface of the glass substrate 40, and is patterned into a shape having an opening in a portion that becomes a flow path by photolithography. Using the resist pattern 42 as a mask, the surface of the glass substrate 40 is etched to a predetermined depth by a wet etching method or a dry etching method to form a groove 44 serving as a microchannel. The shape of the groove 44 is such that one end of the flow path 44b branches into two flow paths 42a and 42d and the other end branches into two flow paths 42c and 42e.

  (B) A through hole 46 is opened from the other surface side of the substrate 40 at each end of the branch flow paths 42a, 42d, 42c, and 42e. The through hole 46 can be opened by a wet etching method, a dry etching method, or a physical method such as sandblasting.

  (C) The other glass substrate 48 is bonded to the surface of the substrate 40 where the groove 44 is formed. For example, the bonding can be performed by fusing and bonding the two substrates 40 and 48 with a hydrofluoric acid solution interposed therebetween.

(D) A metal film 50 serving as an electrode is formed on the outer surfaces of the substrates 40 and 48 by vapor deposition or sputtering.
(E) The metal film 50 is patterned into the shape of the electrodes 52a and 52b by photolithography and etching. The electrodes 52a and 52b are formed so as to exist from one side to the center of the flow path 44b.

  The operation of the obtained liquid-liquid extraction apparatus will be described with reference to the enlarged view of FIG. 5 as well. A solution A containing a solute is supplied from the through hole of the branch channel 44a on one end side, and the other end passes through the channel 44b. It is discharged from the through hole of the side branch passage 44c. The other liquid B is supplied from the through hole of the branch flow path 44d on one end side, and is discharged from the through hole of the branch flow path 44e on the other end side through the flow path 44b. In the flow path 44b, both liquids A and B flow while contacting at the interface. At this time, when an alternating current voltage is applied between the electrodes 52a and 52b from the alternating current power source 14, the electrodes 52a and 52b exist only in the region where the liquid B flows. An electric field gradient that becomes stronger as it approaches the interface is generated, and the solute 8 in the solution A moves toward the interface by dielectrophoresis and is extracted into the liquid B.

As the substrates 40 and 48, in addition to a glass substrate, a silicon substrate, a plastic material such as PDMS (polydimethylsiloxane), or the like can also be used. For example, when PDMS is used as the substrate 40, the groove 44 and the through hole 46 can be formed by molding.
Further, the substrates 40 and 48 may be bonded together with an adhesive.

The liquid-liquid extraction apparatus of the present invention can be used in a chemical system for treating a substance in a micro solution, for example, a microorganism, a protein, a nucleic acid, a carbohydrate, an antigen, an antibody, or a mixture in which these are bound. Suitable for use in micronizing and integrating chemical systems. For example, if a separation method using a liquid as a mobile phase, such as liquid chromatography (LC) or capillary electrophoresis (CE), is used as a pretreatment device, a sample with high purity can be supplied.
In the present invention, since the extraction rate depends on the polarization characteristics, when two or more kinds of solutes are present, the solute to be extracted and the solute not to be extracted can be selected according to the polarization characteristics. You can also.

It is a schematic plan view which shows one Example. It is a schematic plan view which expands and shows the interface vicinity in the Example. It is a schematic plan view which shows another Example. It is process drawing which shows another Example with a manufacturing method. (A) is an enlarged cross-sectional view for explaining the operation in the same embodiment, (B) right side view is an enlarged cross-sectional view of the flow path portion, and (B) left side view is a flow of liquid flowing through the flow path. It is sectional drawing seen from the direction perpendicular | vertical to. It is a schematic plan view which shows the conventional microchannel.

Explanation of symbols

4, 6, 22 Pump of liquid feeding mechanism 2, 20, 44 Micro flow path 8 Extracted solute 10, 24 Interface 12a, 12b, 26a, 26b, 52a, 52b Electrode 16, 30 Electric field lines 14, 28 AC power supply

Claims (2)

A micro flow path in which a solution to be extracted containing a solute to be extracted and a solvent for extracting the solute contact each other at an interface and flow in a laminar flow;
A liquid feeding mechanism for supplying the solution to be extracted and the solvent to the flow path;
An electric field application mechanism for applying an electric field gradient that dielectrophores the solute in the extraction solution in the interface direction in the flow path. One or more stages of microchannels are disposed downstream of the channel,
The downstream microchannels of each stage are configured such that the solvent from which the solute was extracted in the immediately preceding microchannel and the other solvent are in contact with each other at the interface and flow in a laminar flow. The liquid feeding mechanism to supply, The electric field application mechanism which acts on the electric field gradient which carries out the dielectrophoresis of the solute in the solvent from the front | former stage which extracted the solute to the interface direction with the said other solvent is further provided. Liquid-liquid extraction device.

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