A clip for holding a microfluidic device

Abstract

A clip (1) for holding a microfluidic device (50) with a generally planar bottom surface (51) and generally planar top surface (52), includes a base (20) with a supporting surface (21) to support the bottom surface (51) of the microfluidic device (50); a cover (30) to hold the microfluidic device (50) on the supporting surface (21) of the base (20); a hinge (40) connecting the cover (30) to the base (20) for rotation of the cover (30) about a hinge axis (41); a pressure plate (31) mounted to the cover (30) for relative rotation about a rotation axis (32) extending parallel to the hinge axis (41), the pressure plate (31) has an abutment surface (33) for engagement with the top surface (52) of the microfluidic device (50); and a clamp mechanism (61) to releasably secure the cover (30) to the base (20) to compressively hold the microfluidic device (50) between the supporting surface (21) and the abutment surface (33). The rotatable pressure plate (31) pressing flush onto the top surface (52) allows the compression applied by the clamp (61) across the microfluidic device (50) to be more uniform. (Fig. 4 to accompany Abstract)

Description

A CLIP FOR HOLDING A MICROFLUIDIC DEVICEField of the invention

[0001] The present invention generally relates to a clip and in particular to a clip for holding a microfluidic device.Background of the invention

[0002] Any discussion of the prior art throughout the specification should not be considered an admission that such prior art is widely known or forms part of common general knowledge in the field.

[0003] Microfluidic devices are often manufactured by joining together two or more layers of material, where at least one layer includes a microfluidic feature such as a microchannel. The layers need to be adequately joined together so that no leakage occurs between the layers.

[0004] The layers of a microfluidic device are often permanently bonded together, for example using plasma-bonding techniques. However, plasma-bonding is irreversible and microfluidic devices manufactured with this process frequently have leaks. Further, plasmabonding techniques are often expensive.

[0005] When holding the layers of a microfluidic device together, a mechanical clip may be used to compressively engage the top and bottom layers, respectively. However, these mechanical clip systems are typically produced for use with microfluidic devices of a particular thickness and may not adequately hold microfluidic devices of different thicknesses. Holding a microfluidic device that is thicker (or thinner) than the microfluidic devices intended for use with a mechanical clip can lead to possible leaks, and the clip may be difficult or awkward to use.

[0006] It is an object of the present invention to overcome or ameliorate at least one of the disadvantages of the prior art, or to provide a useful alternative.

[0007] It is an object of some embodiments of the present invention to provide a clip for holding a microfluidic device that can readily accept microfluidic devices of different thicknesses and is relatively easy to use.Summary of the invention

[0008] According to one aspect of the present invention, there is provided a clip for holding a microfluidic device with a generally planar bottom surface and generally planar top surface, the clip comprising: a base with a supporting surface to support the bottom surface of the microfluidic device; a cover to hold the microfluidic device on the supporting surface of the base; a hinge connecting the cover to the base for rotation of the cover about a hinge axis; a pressure plate mounted to the cover for relative rotation about a rotation axis extending parallel to the hinge axis, the pressure plate has an abutment surface for engagement with the top surface of the microfluidic device; and a clamp mechanism to releasably secure the cover to the base to compressively hold the microfluidic device between the supporting surface and the abutment surface.

[0009] Preferably, the abutment surface is generally planar and elongate such that the rotation axis is parallel to a longitudinal extent of the abutment surface.

[0010] The rotation axis preferably substantially bisects a width dimension of the abutment surface.

[0011] Preferably, the cover comprises a peripheral frame to laterally surround the pressure plate such that the pressure plate is rotatable about the rotation axis within the peripheral frame.

[0012] Preferably, the clamp mechanism is adjustable to vary compression on the microfluidic device between the supporting surface and the abutment surface.

[0013] The clamp mechanism is preferably manually adjustable.

[0014] Preferably, the clamp mechanism has a clamp with an internally threaded bore and a manually rotatable threaded shaft with a complementary external thread.

[0015] The threaded shaft preferably has a longitudinal axis and is mounted for angular movement relative to the supporting surface of the base.

[0016] Preferably, the clamp is rotatably mounted to the base.

[0017] In some embodiments, the clamp mechanism has a threaded shaft and a manually rotatable nut with a complementary internal thread.

[0018] Preferably, the pressure plate has at least one aperture for fluidic connections to the microfluidic device.

[0019] The base preferably has a viewing aperture for viewing the microfluidic device.

[0020] Preferably, the viewing aperture has a chamfered periphery to allow the lens of an inverted microscope with a frusto-conical end formation to be positioned closely adjacent the generally planar bottom surface of the microfluidic device, and closely adjacent the chamfered periphery of the viewing aperture.

[0021] The supporting surface of the base is preferably configured to receive a standard microscope slide.

[0022] Preferably, the hinge comprises first complementary structural features integrally formed on the base and the cover, respectively.

[0023] The first complementary structural features preferably snap-fit together to connect the base and the cover.

[0024] Preferably, each of the peripheral frame and the pressure plate comprises respective integrally formed second complementary structural features.

[0025] The second complementary structural features preferably snap-fit together to connect the peripheral frame and the pressure plate.

[0026] Preferably, the base, the peripheral frame and the pressure plate are each one- piece components.

[0027] The base, the cover and the pressure plate are preferably formed from autoclavable polymer material.

[0028] Preferably, the base, the cover and the pressure plate are formed from polypropylene or PEEK.

[0029] The base, the cover and / or the pressure plate preferably comprise an embedded reinforcing element.

[0030] Preferably, the reinforcing element comprises metal.

[0031] The clamp mechanism preferably provides at least one predetermined setting for applying an associated level of compressive force to the microfluidic device.

[0032] Preferably, the clamp mechanism includes a force sensor for providing an output indicative of the at least one predetermined setting.

[0033] The clamp mechanism preferably includes an LED indicator responsive to the output from the force sensor.

[0034] In some embodiments, the clamp mechanism includes a piezo-electric element for providing an output indicative of the at least one predetermined setting. In other embodiments, the clamp mechanism includes a mechanical force gauge providing an output indicative of the at least one predetermined setting.

[0035] Unless the context clearly requires otherwise, throughout the description and the claims, the words “comprise”, “comprising”, and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is to say, in the sense of “including, but not limited to”.Brief description of the drawings

[0036] A preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which:

[0037] Figure 1 is a perspective view of a clip for holding a microfluidic device in an open configuration;

[0038] Figure 2 is a perspective view of the clip of Figure 1 in a closed configuration;

[0039] Figure 3 is an exploded perspective view of the clip of Figure 1 ;

[0040] Figure 4 is a side view of the clip of Figure 1 shown in use with a microfluidic device of a first thickness;

[0041] Figure 5 is a side view of the clip of Figure 1 shown in use with a microfluidic device of a second thickness;

[0042] Figure 6 is a side view of the clip of Figure 1 shown in use with a microfluidic device of a third thickness; and

[0043] Figure 7 is a cross sectional side view of the clip of Figure 1 shown in use with an inverted microscope viewing the microfluidic device through an aperture in the base.Detailed description of the embodiments

[0044] Figure 1 shows a clip 1 for holding a microfluidic device. The clip 1 has a base 20 with a supporting surface 21 to support a bottom surface of a microfluidic device, a cover 30 to hold the microfluidic device on the supporting surface 21 of the base 20 and a hinge 40 connecting the cover to the base for rotation of the cover about a hinge axis 41 . A pressure plate 31 is mounted to the cover 30 for relative rotation about a rotation axis 32 extending parallel to the hinge axis 42. The pressure plate 31 has an abutment surface 33 for engagement with a top surface of the microfluidic device. As best shown in Figures 4 to 6, the microfluidic device 50 has a generally planar bottom surface 51 and a generally planar top surface 52. A clamp mechanism 60 is provided to releasably secure the cover 30 to the base 20 to compressively hold the microfluidic device between the supporting surface 21 and the abutment surface 32.

[0045] As best shown in Figures 1 to 3, the abutment surface 33 of the pressure plate 31 is generally planar and elongate, with the rotation axis 32 extending longitudinally along the pressure plate and bisecting a width dimension of the abutment surface, such that the rotation axis 32 is parallel to a longitudinal extent of the abutment surface 33. The cover 30 comprises a peripheral frame 34 that laterally surrounds the pressure plate such that the pressure plate is rotatable within the peripheral frame. The peripheral frame 34 and the pressure plate 31 include complementary structural features in the form of axles 35 formed on the pressure plate 31 and axle receiving recesses 36 formed on an inside surface 37 of the peripheral frame 34. The axles 35 and the axle receiving recesses 36 can snap fittogether to rotatably mount the pressure plate to the cover, thereby defining the rotation axis 32.

[0046] As shown in Figures 1 , 2 and 3, the pressure plate 31 has at least one aperture 67 for fluidic connections to the microfluidic device. Conveniently, the pressure plate may have a series of identical apertures 67 or non-identical apertures formed in predetermined positions in the pressure plate during the moulding process. In other forms, the apertures 67 may be formed after the pressure plate is produced. For example, the pressure plate 31 may incorporate two drilled holes, which are designed to be aligned with corresponding inlet and outlet ports on the microfluidic device 50. The two drilled holes would then serve as the inlet and outlet of a microfluidic feature of the microfluidic device 50, such as a microfluidic channel.

[0047] As best shown in Figure 3, the hinge 40 comprises complementary structural features in the form of clipping formations 42 formed on the base 20 and corresponding shafts 43 formed on the cover 30. The clipping formations 42 and the shafts 43 can snap-fit together to hingedly connect the base and the cover, thereby defining the hinge axis 41 .

[0048] The clamp mechanism 60 includes a clamp 61 with an internally threaded bore 62 and a manually rotatable threaded shaft 63 with a complementary external thread, such that the clamp mechanism is manually adjustable to vary compression on the microfluidic device between the supporting surface 21 and the abutment surface 33. The clamp 61 is rotatably mounted on the base such that a longitudinal axis 64 of the threaded shaft 63 is angularly movable relative to the supporting surface 21 of the base. In the preferred embodiment shown in Figures 1 to 7, the clamp mechanism includes two internally threaded bores 62 and two threaded shafts 63. However, it will be appreciated any desired number of threaded bores and shafts may be used to suit the requirements of other embodiments of the clip. In alternative embodiments, the clamp mechanism may include an externally threaded shaft and a manually rotatable nut with a complementary internal thread. Other mechanisms for effecting a clamping force to secure the cover to the base may be used such as a spring- loaded clamp mechanism, a lever loaded clamp mechanism, a cam mechanism or a toggle clamp.

[0049] As best shown in Figure 3, the clamp 61 and the base 20 may include complementary structural features in the form of clamp clipping formations 24 formed on the base 20 and corresponding clamp shafts 66 formed on the clamp 61 . The clamp clippingformations 24 and the clamp shafts 66 can snap-fit together to rotatably mount the clamp 61 on the base 20.

[0050] When using clip 1 to hold a microfluidic device, a planar bottom surface of the microfluidic device (for example, in the form of a bottom surface of a microscope slide), is placed on the supporting surface 21 of the base 20. The cover 30 is then rotated relative to the base until the abutment surface 33 engages a top surface of the microfluidic device. Clamp 61 may then be rotated relative to the base until the longitudinal axis 64 of the threaded shaft 63 is substantially perpendicular to the top surface 52 of the microfluidic device 50. The threaded shaft 63 can then be rotated with respect to the internally threaded bore 62 thereby moving the threaded shaft towards the peripheral frame 64 until an end 65 of the threaded shaft abuts a portion of the peripheral frame 64, thereby forcing the peripheral frame against the base and compressing the microfluidic device 50 between the supporting surface 21 and the abutment surface 33.

[0051] The compression between the supporting surface 21 and the abutment surface 33 forces the layers of the microfluidic device 50 together thereby creating a substantially leak free microfluidic environment. For example, a bottom layer of the microfluidic device may be a microscope slide and a top layer could be a layer of material including microfluidic features such as a microfluidic channel on one of its surfaces. Contact force between the microscope slide and the surface including the microfluidic channel seals the microfluidic channel against the microscope slide, such that the microscope slide acts as the base of the microfluidic channel. Alternatively, the microfluidic device may comprise a first layer and a second layer, and each layer includes an inner surface with corresponding complementary microfluidic features such that when the inner surfaces are pressed together a microfluidic channel is defined.

[0052] After use, the threaded shaft 63 can be unthreaded from the internally threaded bore 62 until the end 65 of the threaded shaft is separated from the peripheral frame thereby releasing compression force on the microfluidic device and allowing the clamp 61 to be rotated outwardly away from the cover 30. The cover 30 can then be rotated about the hinge axis 41 to move the abutment surface 33 of the pressure plate 31 out of engagement with the top surface 52 of the microfluidic device 50. The microfluidic device can then be removed for further analysis and / or cleaning, thereby facilitating reuse of the microfluidic device 50 and the clip 1 . The reusability of both the clip and the microfluidic device significantly reduces waste and costs, providing a sustainable solution for microfluidic applications.

[0053] Referring to Figures 4 to 6, it will be appreciated that microfluidic devices 50 of different thicknesses may be placed on the clip 1 and the pressure plate 31 is able to rotate relative to the peripheral frame such that the abutment surface 33 engages the top surface 52 in a substantially planar manner. For example, in Figure 4 the clip 1 is shown in use while holding a microfluidic device 50 of thickness X. The peripheral frame 34 is upwardly angled relative to the top surface 52 of the microfluidic device, but the pressure plate is angled relative to the peripheral frame such that the abutment surface 33 engages the top surface in a substantially planar manner.

[0054] In another example, shown in Figure 5, the microfluidic device has a thickness Y that is smaller than X. The peripheral frame 34 is downwardly angled relative to the top surface 52 of the microfluidic device, but the pressure plate is again angled relative to the peripheral frame to allow the abutment surface 33 to engage the top surface 52 in a substantially planar manner.

[0055] In a further example, shown in Figure 6, the microfluidic device has a thickness Z that is smaller than X but larger than Y. The peripheral frame 34 is only slightly downwardly angled relative to the top surface 52 of the microfluidic device such that the pressure plate is only slightly angled relative to the peripheral frame. This again results in the abutment surface 33 engaging the top surface 52 in a substantially planar manner.

[0056] Since the abutment surface engages the top surface in a substantially planar manner, the resulting pressure applied on the top surface 52 is substantially even over the top surface. Advantageously, this reduces the likelihood of a leak occurring between the layers of the microfluidic device, for example in the interface between a top surface of a microscope slide and a bottom surface of another layer of the microfluidic device. The device is therefore able to readily accommodate microfluidic devices of different thicknesses.

[0057] Referring to Figure 7, the base 20 has a viewing aperture 22 for viewing the microfluidic device. The supporting surface 21 of the base is configured to receive a standard 75mm x 25 mm microscope slide, and the viewing aperture is large enough to allow viewing of the standard microscope slide. In use, the microscopic slide would be pressed against the bottom surface of a layer of the microfluidic device 50 and would act as the base of a flow channel of the microfluidic device, thereby allowing a user to see the flow channel. Advantageously, the viewing aperture may have a chamfered periphery 23 to allow the lens of an inverted microscope 70 with a frusto-conical end formation 71 to be positionedclosely adjacent the generally planar bottom surface of the microfluidic device, and closely adjacent the chamfered periphery of the viewing aperture.

[0058] The base 20, the peripheral frame 34 and the pressure plate 31 can be one-piece components, preferably made out of durable and chemically resistant plastics material. In the preferred embodiment, the base, the cover and the pressure plate are integrally formed from autoclavable polymer material, such as polypropylene or PEEK.

[0059] The base, the cover and / or the pressure plate may comprise an embedded reinforcing element. For example, a metal element may be embedded in any of the base, the cover and / or the pressure plate to provide additional mechanical resistance, if required.

[0060] The clamp mechanism may provide at least one predetermined setting for applying an associated level of compressive force to the microfluidic device. For example, the clamp mechanism may include a force sensor for providing an output indicative of the at least one predetermined setting. The force sensor may be an electronic force sensor operatively associated with an indicator, such as an LED, responsive to the output from the force sensor so that a user can observe if the predetermined setting of compressive force has been achieved.

[0061] Alternatively, the clamp mechanism may include a mechanical force gauge for providing an output indicative of the at least one predetermined setting. The mechanical force gauge may be miniaturized to be embedded in the clamp 61 or another element of the clip 1 , such as the base 20 or the cover 30. The mechanical gauge may include a dial to allow a user to observe if the predetermined setting of compressive force has been achieved.

[0062] In other embodiments, the clamp mechanism may include a piezo-electric element for providing an output indicative of the predetermined setting. The piezo-electric element may be located, for example, at the clamp 61 , such that is it responsive to stress and / or strain in the clamp 61 due to forces exerted on the cover 30. The clamp mechanism may also include an indicator, such as an LED, responsive to the output from the piezo-electric element so that a user can observe if the predetermined setting of compressive force has been achieved.

[0063] Although the invention has been described with reference to a specific example, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims

CLAIMS1 . A clip for holding a microfluidic device with a generally planar bottom surface and generally planar top surface, the clip comprising: a base with a supporting surface to support the bottom surface of the microfluidic device; a cover to hold the microfluidic device on the supporting surface of the base; a hinge connecting the cover to the base for rotation of the cover about a hinge axis; a pressure plate mounted to the cover for relative rotation about a rotation axis extending parallel to the hinge axis, the pressure plate has an abutment surface for engagement with the top surface of the microfluidic device; and a clamp mechanism to releasably secure the cover to the base to compressively hold the microfluidic device between the supporting surface and the abutment surface.

2. A clip according to claim 1 , wherein the abutment surface is generally planar and elongate such that the rotation axis is parallel to a longitudinal extent of the abutment surface.

3. A clip according to claim 2, wherein the rotation axis substantially bisects a width dimension of the abutment surface.

4. A clip according to any one of the preceding claims, wherein the cover comprises a peripheral frame to laterally surround the pressure plate such that the pressure plate is rotatable about the rotation axis within the peripheral frame.

5. A clip according to any one of the preceding claims, wherein the clamp mechanism is adjustable to vary compression on the microfluidic device between the supporting surface and the abutment surface.

6. A clip according to claim 5, wherein the clamp mechanism is manually adjustable.

7. A clip according to claim 6, wherein the clamp mechanism has a clamp with an internally threaded bore and a manually rotatable threaded shaft with a complementary external thread.

8. A clip according to claim 7, wherein the threaded shaft has a longitudinal axis and is mounted for angular movement relative to the supporting surface of the base.

9. A clip according to claim 7 or claim 8, wherein the clamp is rotatably mounted to the base.

10. A clip according to any one of the preceding claims, wherein the pressure plate has at least one aperture for fluidic connections to the microfluidic device.

11. A clip according to any one of the preceding claims, wherein the base has a viewing aperture for viewing the microfluidic device.

12. A clip according to claim 11 , wherein the viewing aperture has a chamfered periphery to allow the lens of an inverted microscope with a frusto-conical end formation to be positioned closely adjacent the generally planar bottom surface of the microfluidic device, and closely adjacent the chamfered periphery of the viewing aperture.

13. A clip according to any one of the preceding claims, wherein the supporting surface of the base is configured to receive a standard microscope slide.

14. A clip according to any one of the preceding claims, wherein the hinge comprises first complementary structural features integrally formed on the base and the cover, respectively.

15. A clip according to claim 14, wherein the first complementary structural features snap-fit together to connect the base and the cover.

16. A clip according to any one of the preceding claims, wherein each of the peripheral frame and the pressure plate comprises respective integrally formed second complementary structural features.

17. A clip according to claim 16, wherein the second complementary structural features snap-fit together to connect the peripheral frame and the pressure plate.

18. A clip according to any one of the preceding claims, wherein the base, the cover and the pressure plate are each one-piece components.

19. A clip according to any one of the preceding claims, wherein the base, the cover and / or the pressure plate are formed from autoclavable polymer material.

20. A clip according to any one of the preceding claims, wherein the base, the cover and / or the pressure plate are formed from polypropylene or PEEK.21 . A clip according to any one of the preceding claims, wherein the base, the cover and / or the pressure plate comprise an embedded reinforcing element.

22. A clip according to claim 21 , wherein the reinforcing element comprises metal.

23. A clip according to any one of the preceding claims, wherein the clamp mechanism provides at least one predetermined setting for applying an associated level of compressive force to the microfluidic device.

24. A clip according to claim 23, wherein the clamp mechanism includes a force sensor for providing an output indicative of the at least one predetermined setting.

25. A clip according to claim 24, wherein the clamp mechanism includes an LED indicator responsive to the output from the force sensor.

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