WO2004088148A1

WO2004088148A1 - Fluidic devices

Info

Publication number: WO2004088148A1
Application number: PCT/GB2004/001290
Authority: WO
Inventors: Joseph Cefai; Julian Shapley; Peter Martineau
Original assignee: Starbridge Systems Ltd
Current assignee: Starbridge Systems Ltd
Priority date: 2003-04-02
Filing date: 2004-03-24
Publication date: 2004-10-14
Anticipated expiration: 2005-10-02
Also published as: GB0307620D0; GB2400158B; GB2400158A

Abstract

A fluidic device comprising a housing having an inlet (10) and an outlet (12) defining a fluid flow path (14) therebetween. A channel (16) is provided within the housing, which channel (16) is filled with a material (18), such as wax, which supports a reversible, electromagnetic energy activated change in plasticity and/or deformability. The channel (16) filled with material is covered (or enclosed) by a resiliently flexible membrane (20). A port (22) is provided in the housing for the application of pressure or vacuum to the material (18) in the channel (16). A valve seat (24) is provided between the inlet (10) and the outlet. When no electromagnetic energy is applied to the wax (18), it is in a substantially solid state and remains stationary within the channel (16). In use, to open the valve, the wax is melted by the application of electromagnetic energy thereto, and a vacuum is applied to the port (22), such that the portion of the membrane (20) adjacent the valve seat (24) is pulled down, away from the valve seat (24) as the molten wax is drawn back by the vacuum, thereby opening the fluid flow path (14) between the inlet (10) and the outlet (12). With the vacuum still being applied to the port (22), the wax is allowed (or caused) to cool, and the wax (18) solidifies, locking the valve in the open position. In order to close the valve, pressure is applied to the port (22) and the wax (18) is melted by the application of electromagnetic energy thereto. The pressure applied via port (22) pushes the wax forward along the channel (16) toward the fluid flow path (14). The build-up of pressure causes the portion of the membrane (20) adjacent the valve seat (24) to be pushed upwards toward the valve seat (24), thereby blocking the fluid flow path (14) and closing the valve. With pressure being applied to the port (22), the wax (18) is allowed (or caused) to cool, such that it solidifies, locking the valve in the closed position.

Description

Fluidic Devices

This invention relates generally to fluidic devices and more particularly, but not necessarily exclusively, to microfluidic devices having a thermo-responsive material operative to control the flow of fluids in a microfluidic device.

There has been growing interest in the manufacture and use of microfluidic systems. For example, microfluidic systems are known for use as a diagnostic tool for drug discovery, such as DNA and peptide sequencing, and for capillary electrophoresis, liquid chromatography, flow injection analysis, and chemical reaction and synthesis.

Many methods have been described to control the flow or direction of fluids, for example, samples, analytes, buffers and reagents, within these microfluidic systems or devices by, for example, mechanical micropumps and valves within the device. Various efforts have been made to build miniature valves and pumps for microfluidic systems. Several valves and pumps have been disclosed using mechanical actuators, such as piezoelectric actuators or spring-loaded magnetic actuators.

There are problems, however, with such known microfluidic devices in that many are complex in design, difficult to fabricate and/or suffer from a lack of mechanical durability or reliability. In addition, certain known valves for microfluidic devices are prone to leakage due to inadequate seals.

We have now devised an improved arrangement.

In accordance with the present invention, there is provided a fluidic device comprising an inlet and an outlet having a fluid flow path therebetween, a control member movable relative to said fluid flow path between a first position in which said fluid flow path is open and a second position in which said fluid flow path is closed, a chamber in communication with said control member, said chamber containing a body of material which is substantially solid at a first temperature and undergoes a reversible change in plasticity and/or deformability at or above a second temperature greater than said first temperature, the device further comprising means for applying pressure and/or a vacuum to said material when said change in plasticity/deformability has been effected by application of electromagnetic energy to at least a portion thereof, so as to effect movement of said material, which movement is translated to a corresponding movement of said control member between said first and second positions.

In a preferred embodiment, the control member comprises a resiliently flexible member, such as a membrane. In one preferred embodiment of the invention, the inlet and the outlet maybe subsequently parallel to each other, with the fluid flow path being substantially perpendicular to both. In this case, the membrane is preferably substantially parallel to the fluid flow path, and arranged to be pushed into the fluid flow path to block it upon application of pressure to the material, and pulled out of the fluid flow path (to open it) upon application of a vacuum to the material.

In one exemplary embodiment of the invention, the control member is provided by a portion of a membrane covering an elongate chamber in which is provided a body of material, such as wax or the like. The chamber may be completely or partially filled with the material. In the case where the chamber is partially filled, the material may or may not be in contact with the control member. In another exemplary embodiment, the chamber may be filled with a fluid, which fluid-filled chamber may be in communication with a body of material, such as wax, preferably via another portion of the membrane.

In yet another exemplary embodiment of the invention, the chamber may be provided by two substantially parallel membranes, extending across a gap between the fluid flow path and a port by means of which a vacuum/pressure may be applied.

In use, electromagnetic energy, most preferably infra-red radiation, is applied to the body of material, such as wax, to change its state from solid to liquid. In order to close the fluid flow path, pressure is applied to the material, which causes a build up of pressure in the chamber, and causes the control member to be pushed into the liquid flow path to block it. In a preferred embodiment, the material is then allowed or caused to cool and solidify before the pressure is removed, so that the device is "locked" in the closed position. In order to open the fluid flow path, the material is once again melted by application of electromagnetic radiation and a vacuum is applied thereto, which creates a suction force in the chamber and pulls the control member out of the fluid flow path, to open it. Once again, the material is then preferably allowed (or caused) to cool and solidify before the vacuum is removed such that the device is "locked" in the open position.

The device of the present invention provides a relatively simple design which is readily miniaturised and the control of application of electromagnetic energy and pressure/vacuum can be provided on-chip, such that operation of each device in a bank of devices on a single chip can be controlled independently.

The present invention also extends to a method of controlling fluid flow in a fluidic device between an inlet and an outlet having a fluid flow path therebetween, comprising the steps of: (i) providing a control member which is movable relative to the fluid flow path between a first position in which said fluid flow path is open and a second position in which said fluid flow path is closed; (ii) providing a chamber in communication with said control member, said chamber containing a body of material which is substantially solid at a first temperature and undergoes a reversible change in plasticity and/or deformability at or above a second temperature greater than the first temperature; (iii) applying electromagnetic energy to at least a portion of said material to effect said change; and (iv) applying pressure and/or a vacuum to said material so as to effect movement thereof, which movement is translated to a corresponding movement of the control member between said first and second positions.

In a preferred embodiment, the method includes the step of allowing or causing the material to cool and solidify after movement of the control member has been effected, so as to lock the control member into said first or second position.

These and other aspects of the invention will be apparent from an elucidated with reference to the embodiments described hereinafter. Embodiments of the present invention will now be described by way of examples only and with reference to the accompanying drawings, in which:

Figure 1 is a schematic cross-sectional view of a fluidic device according to a first exemplary embodiment of the present invention;

Figure 2 is a schematic cross-sectional view of a fluidic device according to a second exemplary embodiment of the present invention;

Figure 3 is a schematic cross-sectional view of a fluidic device according to a third exemplary embodiment of the present invention;

Figure 4 is a schematic cross-sectional view of a fluidic device according to a fourth exemplary embodiment of the present invention; and

Figure 5 is a schematic cross-sectional view of a fluidic device according to a fifth exemplary embodiment of the present invention.

Referring to Figure 1 of the drawings, there is illustrated a fluidic device comprising a housing having an inlet 10 and an outlet 12 defining a fluid flow path 14 therebetween. A channel 16 is provided within the housing, which channel 16 is filled with a material 18, such as wax, which supports a reversible, electromagnetic energy activated change in plasticity and or deformability. The channel 16 filled with material is covered (or enclosed) by a resiliently flexible membrane 20. A port 22 is provided in the housing for the application of pressure or vacuum to the material 18 in the channel 16. A valve seat 24 is provided between the inlet 10 and the outlet.

It will be appreciated that, when no electromagnetic energy is applied to the wax 18, it is in a substantially solid state and remains stationary within the channel 16.

In use, to open the valve, the wax is melted by the application of electromagnetic energy thereto, and a vacuum is applied to the port 22, such that the portion of the membrane 20 adjacent the valve seat 24 is pulled down, away from the valve seat 24 as the molten wax is drawn back by the vacuum, thereby opening the fluid flow path 14 between the inlet 10 and the outlet 12.

With the vacuum still being applied to the port 22, the wax is allowed (or caused) to cool, by simply removing the electromagnetic energy being applied thereto and, optionally, applying some additional cooling means thereto. As a result, the wax 18 solidifies, such that the valve membrane 20 adjacent the valve seat 24 is locked in the pulled-down position shown, i.e. the valve is locked in the open position. The vacuum applied to the port 22 can now be released without having any effect on the valve position.

In order to close the valve, pressure is applied to the port 22 and the wax 18 is melted by the application of electromagnetic energy thereto. The pressure applied via port 22 pushes the wax forward along the channel 16 toward the fluid flow path 14. The build-up of pressure causes the portion of the membrane 20 adj acent the valve seat 24 to be pushed upwards toward the valve seat 24, thereby blocking the fluid flow path 14 and closing the valve.

With pressure being applied to the port 22, the wax 18 is allowed (or caused) to cool, such that it solidifies, locking the valve in the closed position. The pressure applied to the port 22 can now be removed without having any effect of the valve position.

It will be appreciated that the application of vacuum/pressure applied to the port 22, and the application of electromagnetic energy to the wax 18 can be controlled by means provided on a chip. T hus, a chip could be provided comprising a bank of microfluidic devices, the operation of each of which can be controlled independently as set out above.

In all cases, the electromagnetic energy applied to the material 18 is preferably infra-red radiation. In the case of a bank of such devices, one or more electromagnetic energy sources may be provided to actuate all of the devices, or respective one or more sources may be provided for each device. As mentioned above, the material 18 which may be used in a device according to the present invention maybe any material which supports a reversible, electromagnetic energy activated change in plasticity/deformability. The solid state of the memrane and/or the material should allow the device to remain locked in the required position. The material may be treated, if necessary, for example, by the addition of a dye or the like thereto, to improve its electromagnetic absorption properties.

In all cases, the pressure/vacuum may be applied by pneumatic means, hydraulic means, or a combination thereof.

The arrangement illustrated in Figure 2 of the drawings is similar in many respects to that of Figure 1, except in this case, the membrane 20 does not extend across the port 22 and the channel 16 is only about half-filled with wax 18. The pressure/vacuum is applied, via port 22, directly to a molten body of wax 18 to push the portion of the valve membrane 20 adjacent the valve set 24 up toward the valve seat to block the fluid flow pathy 14 or pull that portion of the membrane 20 back from the valve seat 24 to open the fluid flow path 14, respectively.

In the alternative configuration shown in Figure 3 of the drawings, the relatively small body of wax 18 does not come into contact with the portion of the membrane 20 adjacent the valve seat 24. Nevertheless, when pressure is applied to the molten body of wax 18, it is pushed toward that portion of the membrane 20 causing a build-up of pressure within the channel and pushing the membrane 20 up toward the valve seat 24 to close the valve. Similarly, the application of a vacuum to the molten body of wax 18 will ^"cause the wax 18 to be pulled back, thereby releasing the pressure and pulling the portion of the membrane 20 adjacent the valve seat 24 back to open the fluid flow path 14.

Referring to Figure 4 of the drawings, in yet another exemplary embodiment of the present invention, a fluidic device is provided comprising a housing having an inlet 10 and an outlet 12 defining a fluid flow path 14 therebetween. A channel 16 is provided, as in the embodiments described with reference to Figures 1 to 3 of the drawings, but in this case the channel 16 is not filled with wax. Instead, an additional channel 26 is provided which is filled with wax 18, one end of which channel communicates with the first channel 16 via a membrane 20 which extends longitudinally across the whole device. The other end of the second channel 26 communicates with a port 22 by means of which pressure/vacuum can be applied to the device.

In use, electromagnetic energy is applied to the body of wax 18 in the channel 26 and pressure is applied via the port 22. As a result, the molten body of wax 18 is pushed along the channel 26 toward the opening in the first channel 16, thereby causing a build-up of pressure therein and pushing portion of the membrane 20 adjacent the valve seat 24 up toward the valve seat 24, closing the fluid flow path 14. The wax 18 is allowed (or caused) to cool and solidify and the pressure can then be removed without affecting the valve position, as before.

Similarly, to open the valve, electromagnetic energy is applied to the wax 18 to melt it, and a vacuum is applied to the port 22, to pull the molten body of wax 18 back along the second channel 26, away from the first channel 16, so as to pull the portion of the membrane 20 adjacent the valve seat away from the valve seat 24 and open the valve. Once again, the wax 18 is allowed (or caused) to cool and solidify to maintain the valve in position when the vacuum is released.

Referring to Figure 5 of the drawings, a fluidic device according to yet another exemplary embodiment of the invention comprises a housing having an inlet 110 and an outlet 112 defining a fluid flow path 114 and having a valve seat 124 therebetween. A channel 116 is defined by upper and lower membranes 120a, 120b, which channel is filled with a material 118, such as wax. A port 122 is provided, in line with the fluid flow path 114, separated from the fluid flow path 114 by a portion 116a of the channel 116.

In use, to close the valve, electromagnetic energy is provided to the wax 118 to melt it, and pressure is applied via the port 122 to push the portion 116a of the channel 116 up toward the valve seat 124, thereby blocking the fluid flow path 114 and closing the valve. As before, the wax 118 is then allowed (or caused) to cool and solidify, such that the pressure can be released and the valve will remain in the closed position. To open the valve, electromagnetic energy is once again applied to the wax 118 to melt it, an a vacuum is applied to the port 124, to pull the portion 116a of the channel 116 away from the valve seat 124 and open the valve. Once again, when the wax 118 has cooled, the vacuum can be released and the valve will remain in the open position.

It will be appreciated that the alternative configurations described with reference to Figures 2 to 4 in respect of the arrangement shown in Figure 1 can be equally applied to the configuration described with reference to Figure 5. h fact, embodiments of the present invention have been described above by way of examples only and it will be apparent to a person skilled in the art that modifications and variations acn be made to the described embodiments without departing from the scope of the invention as defined by the appended claims.

Claims

CLAIMS:

1. A fluidic device comprising an inlet and an outlet having a fluid flow path therebetween, a control member movable relative to said fluid flow path between the first position which said fluid flow path is open and a second position in which said fluid flow path is closed, a chamber in communication with said control member, said chamber containing a body of material which is substantially solid at a first temperature and undergoes a reversible change in plasticity and/or deformability at or above a second temperature greater than said first temperature, the device further comprising means for applying pressure and/or a vacuum to said material when the said change of plasticity/deformability has been effected by application of electromagnetic energy to a least a portion thereof, so as to effect movement of said material, which movement is translated to a corresponding movement of said control member between said first and second positions.

2. A fluidic device according to claim 1, wherein said control member comprises a resiliently flexible member.

3. A fluidic device according to claim 2, wherein said control member comprises a membrane.

4. A fluidic device according to any one of claims 1 to 3, wherein the inlet and the outlet are substantially parallel to each other, with the fluid flow path being substantially perpendicular to both the inlet and the outlet.

5. A fluidic device according to claim 4, wherein said control member is substantially parallel to said fluid flow path, and arranged to be pushed into the fluid flow path to block it upon application of pressure to the material, and pulled out of the fluid flow path to open it upon application of a vacuum to the material.

6. A fluidic device according to any one of the preceding claims, wherein the control member is provided by a portion of a membrane covering an elongate chamber in which is provided said body of material.

7. A fluidic device according to claim 6, wherein said chamber is substantially completely filled with said material.

8. A fluidic device according to claim 6, wherein said chamber is partially filled with said material.

9. A fluidic device according to claim 8, wherein said material is in contact with said control member.

10. A fluidic device according to claim 8, wherein said material is not in contact with said control member.

11. A fluidic device according to any one of claims 1 to 5, wherein the control member is provided by a portion of a membrane covering an elongate chamber in which is provided a body of fluid, said chamber being in communication with a body of material.

12. A fluidic device according to claim 11, wherein said fluid-filled chamber is in communication with said body of material via another portion of the membrane.

13. A fluidic device according to any one of claims 6 to 12, wherein said chamber is provided by two substantially parallel membranes, extending across a gap between the fluid flow path and a port by means of which a vacuum/pressure maybe applied.

14. A fluidic device according to any one of the preceding claims,, wherein said electromagnetic energy comprises infra-red radiation.

15. A fluidic device according to any one of the preceding claims, wherein said material comprises wax.

16. A fluidic device according to any one of the preceding claims, wherein said material is allowed or caused to cool and solidify after movement of said control member has been effected.

17. A fluid device substantially as herein described, with reference to the accompanying drawings.

18. A method of controlling fluid flow in a fluid device between an inlet and an outlet having a fluid flow path therebetween, comprising the steps of:

(i) providing a control member which is movable relative to the fluid flow path between a first position in which said fluid flow path is open and a second position in which said fluid flow path is closed;

(ii) providing a chamber in communication with said control member, said chamber containing a body of material which is substantially solid at a first temperature and undergoes a reversible change in plasticity and/or deformability at or above a second temperature greater than the first temperature;

(iii) applying electromagnetic energy to at least a portion of said material to effect said change; and

(iv) applying pressure and/or a vacuum to said material so as to effect movement thereof, which movement is translated to a corresponding movement of the control member between said first and second positions.

19. A method according to claim 18, including the step of allowing or causing the material to cool and solidify after movement of the control member has been effected, so as to lock the control member into said first or second position.

20. A method of controlling fluid flow in a fluidic device, the method being substantially as herein described with reference to the accompanying drawings.