GB2424677A

GB2424677A - Fluid dispenser

Info

Publication number: GB2424677A
Application number: GB0612207A
Authority: GB
Inventors: Gillian Mary Greenway; Stephen John Haswell; Paul Andrew Greenwood; Victoria Skelton
Original assignee: University of Hull
Current assignee: University of Hull
Priority date: 2003-08-20
Filing date: 2003-08-20
Publication date: 2006-10-04
Also published as: GB0319577D0; GB2405182A; GB2424676A; GB0612207D0; GB0612206D0; GB2405182B

Abstract

A fluid dispenser comprises a compartment 27 which is adapted for holding a fluid 31 to be dispensed. The compartment 27 has a flexible wall 16. An expeller 12, such as a roller, is provided for compressing the compartment 27, by moving along the flexible wall 16 so as to dispense fluid 31 from the compartment 27 using peristalsis. A drive mechanism 13 is also provided for driving the expeller 12 at a pre-determined rate so that fluid is dispensed at a pre-determined rate. The compartment 27 is completely sealed. The compartment may include a wall which may be pierced to allow fluid to be dispensed from the compartment.

Description

FLUID DISPENSER

The invention relates to a fluid dispenser. Preferably, the fluid dispenser is suitable for dispensing fluid into and pumping fluid through a channel or channels of a micro fluidic device.

A micro fluidic device is the device which has at least one channel for the passage of fluid therethrough. Generally, a micro fluidic device has a plurality of channels which are intercormected in a desired configuration. The or each channel is relatively narrow. The or each channel may have a maximum cross-sectional dimension of no more than 1000 tm. Preferably, the maximum cross-sectional dimension is no more than 500 l.tm, and more preferably, the maximum cross-sectional dimension is no more than 300 tim. Often, the maximum cross-sectional dimension of each channel will be no more than 200 1m. Micro fluidic devices are commonly formed from two or more component members. A groove, or a plurality of grooves, are formed in one or more of the members. The members are then connected together so as to close the grooves and form the channels. The configuration of the channels and their interconnections are almost infinitely variable. Micro fluidic devices may be used for performing chemical reactions, performing chemical analyses, and performing chemical separations. Other uses are known.

There are a variety of ways of pumping fluids, generally liquids, through the channels * 2 of micro fluidic devices. For example, liquids can be moved through channels of micro fluidic devices by applying electrical voltages, so as to cause the liquids to move through the channels by electrokinetic forces. Alternatively, liquids may be pumped through channels by mechanical pumps, such as driven syringe pumps.

However, there remains a need for a device for delivering fluid to and pumping fluid through the channels of micro fluidic devices.

In accordance with an aspect of the invention, there is provided a fluid dispenser comprising: a compartment adapted for holding a fluid to be dispensed, the compartment having a flexible wall; an expeller adapted for compressing the compartment by moving along the flexible wall while pressing on the flexible wall whereby to dispense fluid from the compartment; and a drive mechanism for driving the expeller at a predetermined rate so that fluid is dispensed from the compartment at a predetermined rate; wherein the compartment is completely sealed.

The following is a more detailed description of embodiments of the invention, by way of example, reference being made to the appended schematic drawings in which: Figure 1 is a perspective view of a fluid dispenser connected to a micro fluidic device; Figure 2 is a crosssectional view of part of the fluid dispenser of Figure 1; and Figure 3 is a cross-sectional view of part of an alternative fluid dispenser.

Referring first to Figure 1, the fluid dispenser 10 comprises a fluid holding cartridge 3 11, a roller 12 and a drive mechanism 13, which is shown only partially and schematically, for driving the roller 12 along the cartridge 11 (as described in more detail below).

Referring now to Figures 1 and 2, the cartridge 11 includes a rigid plate 14 having a planar surface 15 and an elastomeric sheet 16 which lies over the planar surface 15.

The elastomeric sheet 16 has a lower surface 17. A large portion 18 of the lower surface 17 of the elastomeric sheet 16 is bonded to the planar surface 15 of the rigid plate 14 by a suitable adhesive. However, first, second, third and fourth oval regions 19, 20, 21, 22 of the elastomeric sheet 16 are not bonded to the planar surface 15 of the rigid plate 14. Additionally, first, second, third and fourth narrow strips 23, 24, 25, 26 of the elastomeric sheet 16 are also not bonded to the planar surface 15.

Figure 2 is a cross-sectional view of the cartridge 11 which shows the first oval region 19 of the elastomeric sheet 16. The plane of Figure 2 lies normal to the length of the first oval region 19. The first oval region 19 of the elastomeric sheet 16 is slightly separated from the planar surface 15 of the rigid plate 14. This separation is exaggerated in Figure 2 for clarity. Accordingly, the first oval region 19 of the elastomeric sheet 16, together with the underlying region of the rigid plate 14 form a first compartment 27 which holds a first liquid 31. In a similar manner, the second, third and fourth oval regions 20, 21, 22 of the elastomeric sheet 16 in combination with the respective underlying regions of the rigid plate 14 form second, third, and fourth compartments 28, 29, 30 which, respectively, hold second, third and fourth liquids 32, 33, 34.

As shown in Figure 1, the lengths of the first, second, third and fourth compartments 27,28, 29, 30 (which have the same oval shapes as the corresponding oval regions of the elastomeric sheet 16) lie parallel to one another. Each oval compartment 27, 28, 29,30 has a first or start end 27a, 28a, 29a, 30a, which is located towards the roller 12 and a second or stop end 27b, 28b, 29b, 30b, which is located away from the roller 12.

The operation of the roller 12 will be described below. However, for the present purposes, it is pointed out that the direction of movement of the roller 12 is that indicated by the arrow 35. As seen in Figure 1, the start end 27a of the first compartment 27 is located before, in relation to the direction of movement of the roller 12, the start end 29a of the third compartment 29, which is located before the start end 28a of the second compartment 28, which is located before the start end 30a of the fourth compartment 30. The significance of this will be discussed below.

Additionally, the stop end 29b of the third compartment 29 is located before the stop ends 27b, 28b, 30b of the first, second and fourth compartments 27, 28, 30. Again, the significance of this will be discussed below. Further, it will be noted that, at its widest point, the first compartment 27 is wider than the second, third and fourth compartments 28, 29, 30. Also, the first compartment 27 is longer than the second and third compartments 28, 29 which in turn, are longer than the fourth compartment 30. Again, the significance of this will be discussed below.

First, second, third and fourth channels 36, 37, 38, 39 are located between, respectively, the first, second, third and fourth narrow strips 23, 24, 25, 26 of the elastomeric sheet 16 and the underlying portions of the rigid plate 14. The first, second, third and fourth channels 36, 37, 38, 39 extend, respectively, from the stop ends 27b, 28b, 29b, 30b of the first, second, third and fourth compartments 27,28,29, 30. Each one of the channels 36, 37, 38, 39 is in fluid communication with the corresponding one of the compartments 27, 28, 29, 30. If desired, grooves may be formed in the rigid plate 14, under the narrow strips 23, 24, 25,26 of the elastomeric sheet 16 so as to increase the cross- sectional areas of the narrow channels 36, 37, 38, 39. The grooves could be formed by lithography and etching.

As seen in Figure 1, the cartridge 11 also includes a connecting block 40. First, second, third and fourth apertures 41,42,43,44 pass through the connecting block 40, so that each one of the apertures 41, 42, 43, 44 is in fluid communication with a respective one of the first, second, third, and fourth channels 36,37,38,39. Each one of the apertures 41, 42, 43, 44, at the end of the aperture which is spaced from the connecting channel 36, 37, 38, 39, is provided with a corresponding septum (not shown) which seals the aperture from the environment. Alternatively, sealing could be achieved using a nut and ferrule system. * 6

The roller 12 can be driven at a pre-determined rate by the drive mechanism 13 (shown only partially and schematically in Figure 1) so that the roller 12 rolls over the cartridge 11 pressing down on the elastomeric sheet 16. This is described in more detail below.

The micro fluidic device 45 shown in Figure 1 is of a well known type. The micro fluidic device 45 is formed from a lower plate 46 and a top plate 47. During manufacture of the micro fluidic device, five grooves were etched into the upper surface of the lower plate 46. The upper surface of the lower plate 46 was then connected to the top plate 47 so that the top plate 47 closed the grooves to form five channels having a configuration similar to that of the five grooves. As shown in Figure 1, the five channels consist of first and second channels 48,49 which meet at a first intersection 53, a third channel 50 which connects the first intersection 53 with a second intersection 54, and fourth and fifth channels 51, 52 which meet with one another and with the third channel 50 at the second intersection 54. Additionally, as shown in dashed lines in Figure 1, four cylindrical reservoirs pass through the top plate 57 of the micro fluidic device 45. A first reservoir 55 connects with the free end of the first channel 48. A second reservoir 56 connects with the free end of the second channel 49. A third reservoir 57 connects with the free end of the fourth channel 51, and the fourth reservoir 58 connects with the free end of the fifth channel 52.

The first reservoir 55 is connected via a branched section of flexible narrow bore tube 59 to two needles 60. The second reservoir 56 is connected by a straight piece of flexible narrow bore tube 59 to a needle 60, and the third reservoir 57 is connected by a straight piece of narrow bore tube 59 to a needle 60. Each needle 60 has a plastic tab, for the purposes of holding the needle, and only the plastic tabs of the needle 60 are visible in Figure 1.

It will be appreciated from the above, that the cartridge 11 provides first, second, third and fourth compartments 27, 28, 29, 30, each containing different respective liquids 31,32, 33, 34, so that the four liquids 31, 32, 33, 34 are completely isolated from the atmosphere (before the septa are punctured by the needles 60 as discussed below) and from one another. Such a cartridge may be prefabricated and, in view of the isolation of the liquids from the atmosphere, may have a substantial shelf life.

The operation of the fluid dispenser 10 is now described. The fluid dispenser 10 is used to dispense and pump the first, second, third and fourth liquids 31,32,33,34 into and through the channels of the micro fluidic device 45, as follows.

Firstly, each needle 60 is passed through a respective one of the septa so that the first aperture 41 is brought into fluid communication with the third reservoir 57 of the micro fluidic device, the second and third apertures 42, 43 are brought into fluid communication, via the Y shaped narrow bore tube 59 with the first reservoir 55, and * 8 the fourth aperture 44 is brought into fluid communication with the second reservoir 56.

The drive mechanism 13 is then engaged and this causes the roller 12 to roll towards the cartridge 11 so that the roller 12 comes into contact with the elastomeric sheet 16.

The roller continues to move, at a pre-determined rate, over the elastomeric sheet 16, pressing against the elastomeric sheet 16.

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The roller first meets the start end 27a of the first compartment 27. As the roller progresses, the roller presses down on the first oval region 19 of the elastomeric sheet 16 and this slowly expels the first liquid 31 from the first compartment 27. The first liquid 31 passes from the first compartment 27, through the first channel 36 and into the first aperture 41. The first liquid 31 then passes into the corresponding needle 60 and via the flexible narrow bore tube 59 into the third reservoir 57 of the micro fluidic device 45. In the micro fluidic device 45, the first liquid 31 passes along the fourth channel 51 to the second intersection 54 and then along the fifth channel 52 to the fourth reservoir 58 which is a waste reservoir.

As can be seen in Figure 1, the roller 12 then meets the start end 29a of the third compartment 29 and, in a similar manner, the roller 12 starts to expel the third liquid 33 from the third compartment 29. The third liquid 33 passes through the third channel 38 and into the third aperture 43 from where the third liquid 33 passes along the Y shaped narrow bore tube 59 to the first reservoir 55 of the micro fluidic device 45. From the first reservoir 55, the third liquid 33 passes into the first channel 48, then into the third channel 50, then into the fifth channel 52 to the fourth waste reservoir 58. As will be appreciated from the above, the third liquid 33 meets with and mixes with the first liquid 31 at the second intersection 54.

As the roller 12 progresses in the direction of travel shown by arrow 35, it next encounters the start end 28a of the second compartment 28. In a similar manner, the roller 12 starts to expel the second liquid 32 from the second compartment 28. The second liquid 32 passes into the second channel 37 and then into the second aperture 42. The second liquid 32 then passes through the corresponding needle 60 and the corresponding narrow bore tube 59 to the first reservoir 55 of the micro fluidic device 45. As the third liquid 33 is already being pumped into the first reservoir 55, the second liquid 32 mixes with third liquid 33 in the first reservoir 55. The mixture then passes through the first channel 48, the third channel 50 and the fifth channel 52 to the fourth waste reservoir 58.

As the roller 12 progresses, the roller then meets the start end 30a of the fourth compartment 30 and starts to expel the fourth liquid 34 from the fourth compartment 30. As can be seen from Figure 1, the fourth liquid 34 is pumped into the second reservoir 56 and then through the second channel 49, the third channel 50 and the fifth channel 52 to the fourth waste reservoir 58. As will be appreciated from the above, the fourth liquid 34 meets with the mixture of the second and third liquids 32, 33 at the first intersection 53. The mixture of the second, third and fourth liquids 32,33,34 meets and mixes with the first liquid 31 at the second intersection 54.

The roller 12 then arrives at the stop end 29b of the third compartment 29. When this occurs, pumping of the third liquid 33 substantially stops.

Subsequently, the roller 12 meets the stop ends 27b, 28b, 30b, of the first, second and fourth compartments 27, 28, 30 and, at that stage, pumping of the first, second and fourth liquids 31, 32, 34 also stops.

As the first compartment 27 is longer than the other compartments, pumping of the first liquid 31 takes place for a greater length of time than pumping of the other liquids - the duration of pumping of each liquid being dependent on the length of the compartment in which the liquid is contained.

Additionally, as the first compartment 37 is broader than the other compartments, the flow rate of the first liquid 31 is greater than the flow rates of the other liquids.

Indeed, it will be appreciated that at any particular point in time, the flow rate of a particular liquid will be directly proportional to the cross-sectional area of the compartment in which the liquid is stored at the point at which the roller 12 is applying pressure to the compartment. As shown in Figure 1, the cross-sectional areas * 11 of the compartments increase from the start end of a compartment to the centre of the compartment, and then decreases from the centre of the compartment to the stop end of the compartment. Accordingly, as the roller 12 passes along the length of the compartment, the flow rate of liquid from the compartment will increase and then decrease in direct proportion to the cross-sectional area of the compartment.

The example given above refers to the first to fourth liquids 31 to 34 simply by way of example, to demonstrate the properties of the fluid dispenser. However, it will be appreciated that the dispenser 10 may be used to dispense, for example, four different liquid reagents which react with one another in a pre-determined order in the micro fluidic device. Alternatively the cartridge may be used to hold fluids used for analysis or separation procedures in a micro fluidic device.

Another possibility is that one of the compartments may be left empty for injection of a sample, e.g. a biological sample, into the empty compartment via the septum. The other compartments may then contain fluids for reading with, analysing and/or separating the sample, in the micro fluidic device.

Hence it will be appreciated that the fluid dispenser described above allows the dispensing of a plurality of fluids into a micro fluidic device and the pumping of the fluid through the channels of the device. The fluids are treated independently in that the flow start time, flow stop time, total flow time and flow rate are independent for * 12 each fluid. Moreover flow rate can be varied for each fluid, independently, over time.

The dispenser is ideal for performing repeated operations, such as routine analyses or separations, a fresh cartridge being used for each operation.

The dispenser described above is preferably dimensioned for dispensing liquids at flow rates of up to about 2 tl/see (per compartment).

It will be appreciated that the fluid dispenser may be adapted in many different ways.

Firstly, the cartridge 11 may be varied to have any number of compartments, the or each compartment having any desired shape and position on the cartridge. In this way flow factors such as rate, start time and stop time can be infinitely varied.

Figure 3 is a cross-sectional view through a compartment of an alternative cartridge.

In the alternative cartridge shown in Figure 3, the rigid plate 6lis provided with a plurality of recesses 62 (one of which is shown in Figure 3). The rigid plate 61 is covered by an elastomerjc sheet 63. As shown in Figure 3, fluid is held in the compartment, in the recess 62 between the rigid plate 61 and the elastomeric sheet 63.

The alternative cartridge shown in FIgure 3 works in a similar way to the cartridge 11 described above. However, as the roller 12 progresses along the cartridge, the roller 12 compresses the elastomeric sheet 63 so that the elastomeric sheet enters into the recess 62. In this way, liquid in the recess 62 is gradually expelled from the compartment.

Instead of the elastomeric sheet 16 used in the cartridge 11 of Figure 2 a flexible, but generally non-resilient sheet may be used. The compartment would be formed by gaps between the non-resilient sheet and the underlying rigid plate 14 in a similar manner to that in cartridge 11 described above.

Where compartments are made by forming recesses in the rigid plate 14, then the rigid plate 14 can be, for example glass, and the recesses can be formed by photolithography and etching.

Where compartments are formed with recesses in the rigid plate 14, the roller may be provided with corresponding projections for entering into the recesses.

Given that the dimensions of the channels in the micro fluidic device are small, and given that the flow rates required along the channels in micro fluidic devices are low, it will be appreciated that the dimensions of the compartments 27, 28, 29, 30 are relatively small. For example, the depth of the compartments, that is to say the depth between the rigid plate 14 and the elastomeric sheet 16 may be, on average, between about 5 im and 500 I.tm. *

The follcing numbered clauses are not claims (and should not be Searched).

They form part of the disclosure of the description. The claims start on page 14.

1. A fluid dispenser comprising: a compartment adapted for holding a fluid to be dispensed, the compartment having a flexible wall; an expeller adapted for compressing the compartment by moving along the flexible wall while pressing on the flexible wall whereby to dispense fluid from the I compartment; and a drive mechanism for driving the expeller at a pre-determined rate so that fluid is dispensed from the compartment at a pre-determinecj flow rate.

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2. A fluid dispenser according to claim 1, wherein the compartment is one of a plurality of compartments adapted for holding respective fluids so that the fluids are separate from one another, each compartment having a respective flexible wall, the * expeller being adapted for simultaneously compressing all the compartments by moving along the flexible walls while pressing on the flexible walls whereby to dispense fluids simultaneously from the compartments.

3. A fluid dispenser according to claim 2, wherein the compartments are elongate and extend generally parallel to one another in a direction, the expeller moving along the flexible walls in said direction so as to dispense the fluids.

4. A fluid dispenser according to claim 3, wherein at least two of the compartments have different cross-sectional areas so that fluids dispensed from said at least two compartments are dispensed at respective different pre-determined flow rates.

5. A fluid dispenser according to claim 3 or claim 4, wherein each compartment has a respective start end and a respective stop end, the start end of each compartment being located before the stop end of the said compartment when considered in respect of said movement of the expeller in said direction.

6. A fluid dispenser according to claim 5, wherein the start end of a first one of the compartments is located before the start end of a second one of the compartments so that dispensing of fluid from the first compartment starts before * dispensing of fluid from the second compartment starts.

7. A fluid dispenser according to claim 5, wherein the stop end of a first one of the compartments is located before the stop end of a second one of the compartments so that dispensing of fluid from the first compartment stops before dispensing of fluid from the second compartment stops.

8. A fluid dispenser according to any one of claims 3 to 7, wherein two or

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more of the compartments have respective different lengths so that dispensing of fluid from said two or more compartments has different respective durations.

9. A fluid dispenser according to any one of claims 2 to 8, wherein all the compartments are provided in a unitary body.

10. A fluid dispenser according to claim 9, wherein the unitary body comprises a member having a surface and a flexible sheet having at least one region connected to the surface and a plurality of regions unconnected to the surface, each said flexible wall being a respective one of said unconnected regions of the flexible sheet and each compartment being adapted for holding fluid between the corresponding unconnected region of the sheet and an underlying portion of the member, the at least one connected region of the sheet being connected to the member for maintaining separation of respective fluids in the compartments.

11. A fluid dispenser according to claim 10, wherein the member is rigid and the member surface is planar.

12. A fluid dispenser according to claim 10 or claim 11, wherein the flexible sheet is elastic. I l

13. A fluid dispenser according to claim 10, wherein the member surface includes respective recesses underlying each unconnected area of the flexible sheet and the flexible sheet being elastic and being pressable into the recesses by the expeller.

14. A fluid dispenser according to any preceding claim, wherein the or at least I one of the compartments is elongate, the elongate compartment having a cross- sectional area which varies along its length, so that the flow rate of fluid dispensed from the elongate compartment varies over time.

15. A fluid dispenser according to any one of claims 1 to 14, wherein the or at least one of the compartments holds a liquid.

* 16. A fluid dispenser according to any one of claims 1 to 14, wherein the or at least one of the compartments is empty for subsequent insertion of a liquid.

17. A fluid dispenser according to any one of claims 2 to 13, wherein at least two of the compartments hold different liquids, respectively.

18. A fluid dispenser according to any one of claims 2 to 13, wherein at least one compartment holds a liquid and at least one compartment is empty for subsequent * insertion of a liquid.

19. A fluid dispenser according to any preceding claim, wherein the or each compartment, the expeller and the drive mechanism are suitable for dispensing a fluid at a flow rate of 2,.sllsec or less from the or each compartment.

20. A fluid dispenser according to any preceding claim, wherein the expeller is a roller which rolls along the or each flexible wall.

21. A fluid dispenser according to claim 20, wherein the roller is essentially cylindrical.

22. A fluid dispenser according to any preceding claim, wherein the or each compartment is completely sealed.

23. A fluid dispenser according to claim 22, wherein the or each compartment includes a wall which may be pierced to allow fluid to be dispensed from the compartment.

24. A fluid dispenser in accordance with any preceding claim and a device having at least one channel for fluid movement therein, the device comprising a first member having at least one groove therein, and a second member connected to the first member so as to close the at least one groove to form said at least one channel, the fluid dispenser being connected to the device so that fluid dispensed from the dispenser passes through said at least one channel.

25. A fluid dispenser according to claim 24, wherein the or each channel of the device has a maximum cross-sectional dimension of no more than 1000,.im, preferably no more than 500 jim, more preferably no more than 300 urn, and most preferably no more than 200 jim.

26. A fluid dispenser in accordance with any one of claims 2 to 13, and a device having a plurality of interconnected channels for fluid movement therethrough, each one of the compartments being connected to a respective one of the channels, wherein fluid dispensed from each compartment is passed through the corresponding one of the channels.

27. A fluid dispenser according to claim 26, wherein each channel has a maximum cross-sectional dimension of no more than 1000 jim, preferably no more than 500 jim, more preferably no more than 30.0 jim, and most preferably no more than 200 urn.

28. A fluid dispenser according to any one claims 24 to 27, including a connector connecting the or one of the compartments to the or the corresponding one of the channels, the connector including a hollow needle which penetrates a septum so as to allow fluid to pass from the compartment through the needle, but so as to prevent leakage of fluid between the needle and the septum.

29. A fluid dispenser according to any one of claims 1 to 23 connected to a micro fluidic device.

30. A fluid dispenser substantially as hereinbefore described with reference to the accompanying drawings.

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Claims

I CLAIMS

1. A fluid dispenser comprising: a compartment adapted for holding a fluid to be dispensed, the compartment having a flexible wall; an expeller adapted for compressing the compartment by moving along the flexible wall while pressing on the flexible wall whereby to dispense fluid from the compartment; and a drive mechanism for driving the expeller at a pre-determined rate so that fluid is dispensed from the compartment at a pre-determined rate; wherein the compartment is completely sealed.

2. A fluid dispenser according to claim 1, wherein the compartment includes a wall which may be pierced to allow fluid to be dispensed from the compartment.

3. A fluid dispenser according to claim 1 or 2, wherein the compartment is one of a plurality of compartments adapted for holding respective fluids so that the fluids are separate from one another, each compartment having a respective flexible wall, the expeller being adapted for simultaneously compressing all the compartments by moving along the flexible walls while pressing on the flexible walls whereby to dispense fluids simultaneously from the compartments.

4. A fluid dispenser according to claim 3, wherein the compartments are

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elongate and extend generally parallel to one another in a direction, the expeller moving along the flexible walls in said direction so as to dispense the fluids.

5. A fluid dispenser according to claim 4, wherein at least two of the compartments have different cross-sectional areas so that fluids dispensed from said at least two compartments are dispensed at respective different pre-determined flow rates.

6. A fluid dispenser according to claim 4 or claim 5, wherein each compartment has a respective start end and a respective stop end, the start end of each compartment being located before the stop end of the said compartment when considered in respect of said movement of the expeller in said direction.

7. A fluid dispenser according to claim 6, wherein the start end of a first one of the compartments is located before the start end of a second one of the compartments so that dispensing of fluid from the first compartment starts before dispensing of fluid from the second compartment starts.

8. A fluid dispenser according to claim 6, wherein the stop end of a first one of the compartments is located before the stop end of a second one of the compartments so that dispensing of fluid from the first compartment stops before dispensing of fluid from the second compartment stops.

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9. A fluid dispenser according to any one of claims 4 to 8, wherein two or more of the compartments have respective different lengths so that dispensing of fluid from said two or more compartments has different respective durations.

10. A fluid dispenser according to any of claims 3 to 9, wherein all the compartments are provided in a unitary body.

11. A fluid dispenser according to claim 10, wherein the unitary body comprises a member having a surface and a flexible sheet having at least one region connected to the surface and a plurality of regions unconnected to the surface, each said flexible wall being a respective one of said unconnected regions of the flexible sheet and each compartment being adapted for holding fluid between the corresponding unconnected region of the sheet and an underlying portion of the member, the at least one connected region of the sheet being connected to the member for maintaining separation of respective fluids in the compartments.

12. A fluid dispenser according to claim 11, wherein the member is rigid and the member surface is planar.

13. A fluid dispenser according to claim 11 or claim 12, wherein the flexible sheet is elastic.

14. A fluid dispenser according to claim 11, wherein the member surface includes respective recesses underlying each unconnected area of the flexible sheet and the flexible sheet being elastic and being pressable into the recesses by the expeller.

15. A fluid dispenser according to any preceding claim, wherein the or at least one of the compartments is elongate, the elongate compartment having a cross- sectional area which varies along its length, so that the flow rate of fluid dispensed from the elongate compartment varies over time.

16. A fluid dispenser according to any one of claims Ito 15, wherein the or at least one of the compartments holds a liquid.

17. A fluid dispenser according to any one of claims I to 15, wherein the or at least one of the compartments is empty for subsequent insertion of a liquid.

18. A fluid dispenser according to any one of claims 3 to 14, wherein at least two of the compartments hold different liquids, respectively.

19. A fluid dispenser according to any one of claims 3 to 14, wherein at least one compartment holds a liquid and at least one compartment is empty for subsequent (

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insertion of a liquid.

20. A fluid dispenser according to any preceding claim, wherein the or each compartment, the expeller and the drive mechanism are suitable for dispensing a fluid at a flow rate of 2 id/sec or less from the or each compartment.

21. A fluid dispenser according to any preceding claim, wherein the expeller is a roller which rolls along the or each flexible wall.

22. A fluid dispenser according to claim 21, wherein the roller is essentially cylindrical.

23. A fluid dispenser according to claim 3 or any claim dependent thereon, wherein each compartment is completely sealed.

24. A fluid dispenser according to claim 23, wherein each compartment includes a wall which may be pierced to allow fluid to be dispensed from the compartment.

25. A fluid dispenser in accordance with any preceding claim and a device having at least one channel for fluid movement therein, the device comprising a first member having at least one groove therein, and a second member connected to the

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first member so as to close the at least one groove to form said at least one channel, the fluid dispenser being connected to the device so that fluid dispensed from the dispenser passes through said at least one channel.

26. A fluid dispenser according to claim 25, wherein the or each channel of the device has a maximum cross-sectional dimension of no more than 1000 jim, preferably no more than 500 jim, more preferably no more than 300 jim, and most preferably no more than 200 J.tm.

27. A fluid dispenser in accordance with any one of claims 3 to 14, and a device having a plurality of interconnected channels for fluid movement therethrough, each one of the compartments being connected to a respective one of the channels, wherein fluid dispensed from each compartment is passed through the corresponding one of the channels.

28. A fluid dispenser according to claim 27, wherein each channel has a maximum cross-sectional dimension of no more than 1000 pm, preferably no more than 500 jim, more preferably no more than 300 pm, and most preferably no more than 200 pm.

29. A fluid dispenser according to any one claims 25 to 28, including a connector connecting the or one of the compartments to the or the corresponding one QL1

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of the channels, the connector including a hollow needle which penetrates a septum so as to allow fluid to pass from the compartment through the needle, but so as to prevent leakage of fluid between the needle and the septum.

30. A fluid dispenser according to any one of claims I to 24 connected to a micro fluidic device.

31. A fluid dispenser substantially as hereinbefore described with reference to the accompanying drawings.