FIELD-FLOW FRACTIONATION DEVICE

Abstract

A separation cell includes a separation channel forming chip and a discharge channel forming chip. The separation cell includes a separation channel forming plate that is provided on the separation channel forming chip and has a flat surface defining a separation channel having a longitudinal direction, a discharge channel forming plate that is provided on the discharge channel forming chip and has a flat surface defining a discharge channel extending along a longitudinal direction of the separation channel, a separation membrane that is provided on the flat surface defining the separation channel on the separation channel forming chip, and is for selectively allowing a carrier fluid to permeate, a porous support plate and is attached to block an opening of the discharge channel, and a positioning structure for positioning the separation channel forming chip and the discharge channel forming chip in a specific geometrical relationship with respect to each other.

Claims

1. A separation cell for a field-flow fractionation device, the separation cell including a separation channel forming chip and a discharge channel forming chip, the separation cell comprising: a separation channel forming plate that is provided on the separation channel forming chip and has a flat surface defining a separation channel having a longitudinal direction; a discharge channel forming plate that is provided on the discharge channel forming chip and has a flat surface defining a discharge channel extending along a longitudinal direction of the separation channel; a separation membrane that is provided on the flat surface defining the separation channel on the separation channel forming chip, the membrane being interposed between the separation channel and the discharge channel, the membrane having a size smaller than that of the separation channel forming plate and larger than that of the separation channel, the membrane being fixed to the separation channel forming plate to block the separation channel, the membrane configured for selectively allowing a carrier fluid to permeate therethrough; a porous support plate provided on the flat surface defining the discharge channel on the discharge channel forming chip, the support plate having property of allowing the carrier fluid to permeate therethrough, the support plate having a size smaller than that of the discharge channel forming plate and equal to or larger than that of the separation membrane, the support plate being attached to block an opening of the discharge channel; and a positioning structure for positioning the separation channel forming chip and the discharge channel forming chip in a specific geometrical relationship with respect to each other, wherein the separation channel forming chip and the discharge channel forming chip are positioned in the specific geometrical relationship by the positioning structure, whereby the separation membrane is wholly supported by the support plate.

2. The separation cell according to claim 1, wherein the separation channel forming plate and the separation membrane are adhered by molecular adhesion.

3. The separation cell according to claim 2, wherein a silicone film is interposed between the separation channel forming plate and the separation film.

4. The separation cell according to claim 1, wherein the positioning structure includes through holes for bolt penetration provided on each of the separation channel forming plate and the discharge channel forming plate and bolts penetrating the through hole, and common bolts are allowed to penetrate the through holes of each of the separation channel forming plate and the discharge channel forming plate, so that the separation channel forming chip and the discharge channel forming chip are positioned in the specific geometrical relationship with respect to each other.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] FIG. 1 is an exploded perspective view as viewed from diagonally above to explain a structure of an embodiment of a separation cell.

[0019] FIG. 2 is a cross-sectional view of a state in which the separation cell of the embodiment is assembled.

[0020] FIG. 3 is a cross-sectional view illustrating a joint portion between a separation channel forming plate and a separation membrane of the embodiment.

EMBODIMENT OF THE INVENTION

[0021] Hereinafter, an embodiment of a separation cell for a field-flow fractionation device will be described with reference to the drawings.

[0022] As shown in FIG. 1, the separation cell includes an upper pressing plate 2, a lower pressing plate 4, a separation channel forming chip 6, and a discharge channel forming chip 12 having a flat plate shape. Then, the separation cell is configured by lamination of the lower pressing plate 4, the discharge channel forming chip 12, the separation channel forming chip 6, and the upper pressing plate 2 in this order from the lower layer side. Through holes through which a fixing bolt 26 (see FIG. 2) penetrates are provided at positions corresponding to each other of these flat plates. Further, an O-ring 18 which is a sealing member is sandwiched between the separation channel forming chip 6 and the discharge channel forming chip 12.

[0023] The upper pressing plate 2 and the lower pressing plate are flat plate-shaped members made from, for example, aluminum. The upper pressing plate 2 is provided with through holes 20, 22, and 24 that respectively constitute an inlet port for allowing a carrier fluid or a sample to flow into a separation channel 3 (see FIG. 2) described later, an outlet port for allowing a fluid that has passed through the separation channel 3 to flow out of the separation channel 3, and an intermediate inlet port for allowing a fluid forming the focus flow to flow into the separation channel.

[0024] The separation channel forming chip 6 includes a separation channel forming plate 8 and a separation membrane 10. The separation channel forming plate 8 is a flat plate made from, for example, poly-ether-ether-ketone (PEEK) resin or polyethylene terephthalate (PET), and has a flat surface provided with a through hole 8a having a longitudinal direction. The through hole 8a serves as the separation channel 3 (see FIG. 2) described later. That is, the flat surface of the separation channel forming plate 8 provided with the through hole 8a is a flat surface that defines the separation channel 3. In the present embodiment, the through hole 8a has a substantially rhombic shape. The separation membrane 10 is a porous membrane made from RC, PES, or the like, and is smaller than the separation channel forming plate 8 and larger than the through hole 8a. The separation membrane 10 is fixed to a central portion of the flat surface (lower surface in the diagram) of the separation channel forming plate 8 so as to block one opening (opening on the lower surface in the diagram) of the through hole 8a of the separation channel forming plate 8.

[0025] The discharge channel forming chip 12 includes a discharge channel forming plate 14 and a support plate 16. Although not shown in FIG. 1, the discharge channel forming plate 14 has a flat surface facing the flat surface on which the through hole 8a of the separation channel forming plate 8 is provided, and a groove serving as a discharge channel 5 is provided on the flat surface so as to face the through hole 8a of the separation channel forming plate 14. The support plate 16 is attached to the flat surface of the discharge channel forming plate 14 so as to block an opening of the groove of the discharge channel forming plate 14. The flat surface of the discharge channel 14 on which the groove serving as the discharge channel 5 is formed is a flat surface defining the discharge channel 5.

[0026] The support plate 16 is for supporting the separation membrane 10 of the separation channel forming chip 6, and has a planar size that is substantially equal to or slightly larger than that of the separation membrane 10. The support plate 16 is a porous plate made from a sintered body or the like. The support plate 16 may be, and does not have to be, completely fixed to the discharge channel forming plate 14. A groove 17 for fitting the O-ring 18 is provided to surround the support plate 16 on the separation channel forming chip 6 side of the discharge channel forming plate 14.

[0027] FIG. 2 shows the separation cell in an assembled state.

[0028] The separation cell is configured in a manner that the flat plate-shaped separation channel forming chip 6 and the discharge channel forming chip 12 are fixed in a state of being positioned in a specific geometrical relationship with respect to each other in a state where the separation channel forming chip 6 and the discharge channel forming chip 12 are sandwiched between the upper pressing plate 2 and the lower pressing plate 4. In the present embodiment, as a positioning structure for positioning the separation channel forming chip 6 and the discharge channel forming chip 12 in a specific geometrical relationship with respect to each other, the bolt 26 penetrating through holes provided on the upper pressing plate 2, the separation channel forming plate 8 of the separation channel forming chip 6, the discharge channel forming plate 14 of the channel forming chip 12, and the lower pressing plate 4, and a nut for fixing the bolt are used. The separation channel forming chip 6 is disposed at a position directly below the upper pressing plate 2, and the discharge channel forming chip 12 is disposed at a position directly above the lower pressing plate 4.

[0029] The through hole 8a provided on the separation channel forming plate 8 has one opening (upper opening in the diagram) closed by the upper pressing plate 2, and the other opening closed by the separation membrane 10, so as to constitute the separation channel 3. The through hole 20 of the separation channel forming plate 8 leads to one end portion of the separation channel 3 and constitutes an inlet port for injecting a carrier fluid or a sample (hereinafter, referred to as the inlet port 20). The through hole 22 of the separation channel forming plate 8 leads to the other end portion of the separation channel 3 and constitutes an outlet port for allowing a fluid to flow out from the separation channel 3 (hereinafter, referred to as the outlet port 22). The through hole 24 of the separation channel forming plate 8 leads to an intermediate portion between one end portion and the other end portion of the separation channel 3 and constitutes an intermediate inlet port through which a fluid for forming a focus flow flows (hereinafter, referred to as the intermediate inlet port 24).

[0030] The entire lower surface of the separation membrane 10 of the separation channel forming chip 6 is supported by the support plate 16 of the discharge channel forming chip 12. The discharge channel 5 is provided below the support plate 16. The discharge channel 5 is provided along the separation channel 3. Further, although not shown in this diagram, the discharge channel forming chip 12 is also provided with a discharge port for discharging a fluid in the discharge channel 5 to the outside.

[0031] The separation membrane 10 and the support plate 16 are interposed between the separation channel 3 and the discharge channel 5. The separation membrane 10 has the property of allowing a carrier fluid (liquid) to pass through and not allowing sample particles to pass through. The support plate 16 has the property of allowing a carrier fluid that has passed through the separation membrane 10 to pass through while supporting the separation membrane 10. The O-ring 18 is sandwiched between the separation channel forming chip 6 and the discharge channel forming chip 12 to prevent a fluid flowing into the separation channel 3 from leaking to the surroundings.

[0032] The sample particles to be separated and the carrier fluid carrying the sample particles are introduced into the separation channel 3 via the inlet port 20. When the carrier fluid is introduced into the separation channel 3 through the inlet port 3, a flow (channel flow) in the direction toward the outlet port 22 side along the separation channel and a flow (cross flow) in the direction toward the discharge channel 5 by passing through the separation membrane 10 and the support plate 16 are generated. Further, after the sample particles are introduced into the separation channel 3, the carrier fluid is supplied from the intermediate inlet port 24, so that a flow (focus flow) in the direction opposite to the channel flow is generated in the separation channel 3.

[0033] Here, the flow path height of the separation channel 3 is the sum of the thickness of the separation channel forming plate 8 and the thickness of a bonded portion between the separation channel forming plate 8 and the separation membrane 10. When the separation channel forming plate 8 and the separation film 10 are bonded with an adhesive, the flow path height of the separation channel 3 changes depending on the thickness of an adhesive layer between the separation channel forming plate 8 and the separation film 10. However, it is difficult to reproduce the thickness of the adhesive layer between the separation channel forming plate 8 and the separation film 10 that is constant at all the time, and as a result, the reproducibility of the flow path height of the separation channel 3 becomes low. For this reason, the separation channel forming plate 8 and the separation film 10 may be bonded by a method other than the bonding with an adhesive.

[0034] Molecular adhesion is one of the methods of bonding the separation channel forming plate 8 and the separation membrane 10 without using an adhesive. In that case, as shown in FIG. 3, a method of interposing a silicone film 28 having a constant thickness between the separation channel forming plate 8 and the separation film 10 can be mentioned. In this method, the surface of the silicone film 28 is activated by, for example, corona discharge treatment, the separation channel forming plate 8 is adhered to one surface, and the separation film 10 is adhered to the other surface.

[0035] By bonding the separation channel forming plate 8 and the separation membrane 10 by molecular adhesion in this way, the reproducibility of the thickness of the bonded portion between the separation channel forming plate 8 and the separation membrane 10 is improved, and the reproducibility of the flow path height of the separation channel 3 is improved.

[0036] In the separation cell of the present embodiment, the separation channel forming chip 6 is a consumable item, and when the separation membrane 10 needs to be replaced, the separation channel forming chip 6 is replaced together. A relative geometrical relationship between the separation channel forming chip 6 and the upper pressing plate 2 and the discharge channel forming chip 12 is automatically determined by the positioning structure such as the bolt 26. Since the separation membrane 10 is fixed at a predetermined position in the flat surface provided with the through hole 8a of the separation channel forming plate 8, it is not necessary to align the separation membrane 10 alone.

[0037] In the field-flow fractionation device, the analysis is performed in a state where the space inside the O-ring 18 in the separation cell 2 is filled with the carrier fluid. That is, the analysis cannot be started from the start of the supply of the carrier fluid until the space inside the O-ring 18 is filled with the carrier fluid. For this reason, as the volume of the space inside the O-ring 18 is larger, the waiting time from the start of the supply of the carrier fluid to the start of analysis becomes longer.

[0038] In the separation cell of the present embodiment, since the separation membrane 10 is integrated with the separation channel forming plate 8 to constitute the separation channel forming chip 6, position displacement of the separation membrane 10 cannot occur. For this reason, even if the O-ring 18 is disposed at a position closest to the support plate 16, the separation membrane 10 cannot be disposed so as to overlap the O-ring 18 around the support plate 16. For this reason, the volume of the space inside the O-ring 18 can be made smaller than before. By reducing the volume of the space inside the O-ring 18, the waiting time from the start of the supply of the carrier fluid to the start of the analysis can be shortened, and the analysis efficiency can be improved.

DESCRIPTION OF REFERENCE SIGNS

[0039] 2: Upper pressing plate [0040] 3: Separation channel [0041] 4: Lower pressing plate [0042] 5: Discharge channel [0043] 6: Separation channel forming chip [0044] 8: Separation channel forming plate [0045] 8a: Through groove [0046] 10: Separation membrane [0047] 12: Discharge channel forming chip [0048] 14: Discharge channel forming plate [0049] 16: Support plate [0050] 17: Groove [0051] 18: O-ring [0052] 20: Through hole (inlet port) [0053] 22: Through hole (outlet port) [0054] 24: Through hole (intermediate inlet port) [0055] 26: Bolt [0056] 28: Silicone film