Cuvette and method for collecting blood samples - Patents.com

Abstract

A cuvette for collecting a blood sample, the cuvette including a body, a collection opening formed in the body, an inlet opening permitting communication between a first end of the collection opening and an exterior of the cuvette, and a holding chamber formed in the body adjacent a second end of the collection chamber generally opposite the first end, the collection chamber having a first depth, the first depth being the same or substantially the same throughout the collection chamber from the first end to the second end, and the holding chamber having a second, greater depth.

Description

[Technical field]

[0001] The present invention relates to cuvettes, and in particular to cuvettes adapted for collection of fluid samples, for example after centrifugation, and subsequent analysis of the fluid samples.

[0002] Analytical devices are known for determining the optical properties of a fluid contained in a cuvette. In such devices, a cuvette is at least partially filled with a fluid sample for analysis and placed in the device. Optical (or other) radiation is passed through the fluid to enable the properties of the fluid sample to be measured.

[0003] Examples of known types of cuvettes can be found in US Pat. Nos. 5,399,410, 5,497,510, 5,597,620, 5,620,630, and 5,743,645. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent Application Publication No. 2096444 [Patent Document 2] European Patent Application Publication No. 1055112 [Patent Document 3] International Publication No. 2007 / 008137 [Patent Document 4] GB 2555403 Summary of the Invention

[0005] Optical analysis of blood and other liquid samples is used in a wide range of medical diagnostics, including diagnosing anemia. For example, optical analyzers can analyze blood samples to determine hematocrit, and the presence and amount of hemoglobin.

[0006] What is important is that the cuvette can be easily and reliably handled to obtain a blood sample, especially by users with reduced dexterity, coordination or eyesight, and what is also important is that, during use, the cuvette reliably collects the fluid sample and allows analysis of the entire sample in a subsequent step.

[0007] It is an object of the present invention to provide an improved cuvette of this type. Accordingly, one aspect of the present invention is to provide a cuvette for collecting a blood sample, the cuvette including a body, a collection opening formed in the body, an inlet opening allowing communication between a first end of the collection opening and an exterior of the cuvette, and a holding chamber formed in the body adjacent a second end of the collection chamber generally opposite the first end, the collection chamber having a first depth, the first depth being the same or substantially the same throughout the collection chamber from the first end to the second end, and the holding chamber having a second depth which is greater.

[0008] Advantageously, in the region where the collection chamber meets the holding chamber, the collection chamber is generally planar and the holding chamber has a depth on either side of the plane of the collection chamber that is greater than the depth of the collection chamber.

[0009] Preferably, in the region where the collection chamber meets the holding chamber, the collection chamber is generally planar and the holding chamber has a width in a direction generally parallel to the plane of the collection chamber that is greater than the width at the second end of the collection chamber.

[0010] Conveniently, the collection chamber has a pair of side walls.

[0011] Advantageously, the width of the collection chamber defined between the side walls is greater at the first end of the collection chamber than at the intermediate portion.

[0012] Preferably, the width of the collection chamber is greater at the second end than at the intermediate portion.

[0013] Conveniently, the cuvette further comprises one or more communication passages, the first end of which communicates with the holding chamber and the second end of which communicates with the exterior of the cuvette.

[0014] Advantageously, the cuvette comprises two communication passages.

[0015] Preferably, the second ends of the two communication passages are on either side of the inlet opening.

[0016] Conveniently, the cuvette further comprises an analysis chamber, the analysis chamber communicating at a first end with the holding chamber.

[0017] Advantageously, the analysis chamber is surrounded on all or substantially all sides apart from its first end.

[0018] Preferably, the analysis chamber is elongated and has a constant or substantially constant width along its length.

[0019] Conveniently, the analysis chamber is of constant or substantially constant depth along its length.

[0020] Advantageously, the volume of the analysis chamber is the same as or greater than the volume of the collection chamber.

[0021] Preferably, the cuvette further comprises a junction region adjacent the holding chamber, the analysis chamber and the one or more communication passages communicating with the junction region.

[0022] Conveniently, the dimensions of the inlet opening and collection chamber are such that when the inlet opening contacts the blood sample, blood is drawn into the collection chamber by capillary action.

[0023] Advantageously, the dimensions of the collection chamber and the holding chamber are such that blood that is drawn into the collection chamber by capillary action stops when it reaches the holding chamber and is no longer drawn into the holding chamber.

[0024] Preferably, the body is generally planar and the cuvette further includes one or more protrusions extending away from the plane of the body such that when the cuvette is placed on a flat surface, at least a portion of the body is raised above a surface a sufficient distance to allow a person to grasp the cuvette.

[0025] Conveniently, the distance is at least 0.8 cm.

[0026] Advantageously, a pair of projections are provided on opposite sides of the body.

[0027] Preferably the or each projection extends away from the plane of the body in both directions.

[0028] Another aspect of the invention provides a method of collecting a blood sample comprising the steps of contacting an inlet opening of a cuvette as claimed in any preceding claim with a blood sample such that blood is drawn into the collection chamber of the cuvette by capillary action to fill or substantially fill the collection chamber without substantially entering the holding chamber.

[0029] Conveniently, the cuvette is a cuvette as described in any one of the above and the method further comprises the step of subjecting the cuvette to centrifugal force to cause blood in the collection chamber to flow through the holding chamber and into the analysis chamber. [Brief description of the drawings]

[0030] In order that the invention may be more readily understood, embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which:

[0031] [Figure 1] FIG. 1 is a perspective view of a cuvette according to the present invention. [Diagram 2] FIG. 1 is a perspective view of a cuvette according to the present invention. [Diagram 3] FIG. 2 is an enlarged view of one half of the cuvette of FIG. 1. [Figure 4]FIG. 2 is a cross-sectional view of the cuvette of FIG. 1. [Figure 5a-5d] 2 illustrates stages in the use of the cuvette of FIG. 1; [Figure 6] FIG. 2 is an enlarged cross-sectional view of a portion of the cuvette of FIG. 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] 1 and 2 show front and rear perspective views, respectively, of a cuvette 1 embodying the present invention.

[0033] The cuvette 1 has a generally planar body 2. The body 2 has a front end generally designated by the reference numeral 3 and a rear end generally designated by the reference numeral 4.

[0034] The body 2 has a generally rectangular form and, in the embodiment shown, has sides 5 that are generally parallel to one another. The body also has a back surface 6, which is preferably generally perpendicular to the sides 5. In the embodiment shown, there are chamfered or rounded corners 7 between the sides 5 and the back surface 6. These corners 7 increase the ease of handling of the cuvette 1.

[0035] The body 2 also has generally planar upper and lower surfaces 8 and 9 which, in the embodiment shown, are also generally parallel to one another.

[0036] At its front end 3, the cuvette 1 has a protruding apex 10 formed by respective inclined surfaces 11. Each of the inclined surfaces 11 projects from a corner 12 where the inclined surfaces 11 meet the respective side surfaces 5 forward (i.e. in a direction generally passing from the rear end 4 to the front end 3 of the cuvette 1) until the inclined surfaces 11 meet each other at the apex 10. The apexes 10 preferably have a rounded or radiused shape.

[0037] At the forward end of each side 5 a projection 13 projects upwardly and downwardly relative to the body 2. In the example shown the projections 13 project away from the plane of the body 2 and, in the example shown, are generally perpendicular to the plane of the body 2.

[0038] In the example shown, the projections 13 are generally rounded.

[0039] In the absence of protrusions 13, cuvette 1 is generally planar. If cuvette 1 is placed on a flat surface, such as a table top, it may be relatively difficult to grasp and pick up, especially for a user with reduced dexterity, as it will lie flat against the table top.

[0040] However, the presence of the protrusions 13 ensures that when the cuvette 1 is placed on a flat surface, the front end 3 of the body 2 is raised upwards and away from the surface, making it much easier for a user to grasp and pick up the cuvette 1. As the skilled reader will appreciate, it is not necessary for the protrusions to be formed in the exact locations shown in the figures, and any suitable number of protrusions located at any convenient point on the cuvette 1 can be used to improve the ease with which the cuvette can be grasped and picked up.

[0041] In the example shown, the protrusions 13 protrude both upwards and downwards from the body 2, such that the front end 3 of the body 2 is raised above the surface regardless of which way the cuvette 1 is oriented. In other embodiments, the protrusions 13 may protrude from the body 2 in only one direction. In yet a further example, each protrusion protrudes from the body in one direction, but in different directions from each other (e.g., one above and one below the plane of the body). This ensures that one corner of the cuvette is always raised above a flat surface while minimizing the weight of the cuvette.

[0042] In a preferred embodiment, the presence of one or more protrusions 13 means that when the cuvette 1 is placed on a flat surface, at least a portion of the body 2 is raised above the surface a distance that provides sufficient space between the body and the surface so that the cuvette 1 can be easily grasped and picked up by a user. For most users, this distance will be at least 0.8 cm, although the invention is not so limited.

[0043] The cuvette 1 may be formed from two halves, which are manufactured separately and then attached to one another. One half may include the top surface 8 of the cuvette 1 and the other half may include its bottom surface 9. One or both halves may be formed with recesses on their internal surfaces such that when the two halves are fastened together, one or more chambers are present in the body 2 of the cuvette 1. These chambers are described in detail below. However, it should be understood that the invention is not limited to this method of manufacturing the cuvette and that the cuvette may be formed in any other suitable or convenient manner.

[0044] 3, one half 14 of the cuvette 1 is shown in isolation. In some embodiments, indentations are formed on the inner surface of one half of the cuvette and the inner surface of the other half is substantially smooth and / or flat. In other examples, both halves may have indentations formed on their inner surfaces, and when the cuvette is assembled, at least some of the indentations align with each other to form chambers.

[0045] FIG. 3 shows the inner surface 15 of the half 14, ie the surface that resides within the body 2 of the cuvette 1 when the cuvette 1 is fully assembled.

[0046] The majority of the inner surfaces 15 are planar and parallel, presenting a flat inner surface which, in the fully assembled cuvette 1, meets and abuts the inner surface 15 of the other half 14 with no or substantially no gap between the two inner surfaces 15. In this manner, when the inner surfaces are flat, the two halves 14 meet each other to form a substantially solid region of the body 2.

[0047] A collection chamber 16 is formed in the area of ​​apex 10 at front end 3 of half 14. Collection chamber 16 takes the form of a recessed or cut-out area having an inner surface 17 underlying the main area of ​​inner surface 15.

[0048] An inner surface 17 of the collection chamber 16 is preferably parallel to and offset a first distance from the main area of ​​the inner surface 15. The collection chamber 16 extends to the apex 10, and the collection chamber 16 has an inlet opening 18 that preferably extends symmetrically relative to the apex 10.

[0049] In the region of the apex 10, the thickness of the body 2 is preferably reduced. The body 2 may have a tapered cross-section (as shown in the figure), such that the thickness gradually decreases towards the apex 10. This helps to provide a clearly defined "point" that can be used to collect a blood sample, and also allows a user to easily view the collected blood sample. The region of reduced thickness (including any tapering portion) may be, for example, around a quarter, a third or a half of the collection chamber 16 closest to the apex 10.

[0050] The collection chamber 16 has first and second side walls 19 that extend generally rearwardly from each side of the inlet opening 18 .

[0051] In the illustrated embodiment, as the side walls 19 extend rearwardly from the inlet opening 18, the side walls 19 taper inwardly toward one another and then flare out again toward one another, the advantages of which are described in more detail below.

[0052] At its inner end 20 (i.e., the end furthest from the inlet opening 18), the collection chamber 16 meets the holding chamber 21. The holding chamber 21 has a depth greater than the depth of the collection chamber 16. Where the collection chamber 16 meets the holding chamber 21, there is therefore a shoulder at the inner end 20 of the collection chamber 16. At the shoulder, there is a relatively abrupt change in depth between the first, relatively small depth of the collection chamber 16 and the second, relatively large depth of the holding chamber 21. In the illustrated example, the holding chamber 21 is generally rectangular and further extends across the entire width of the inner end 20 of the collection chamber 16. In other words, all parts of the inner end 20 of the collection chamber 16 communicate with the holding chamber 21.

[0053] In the illustrated example, the holding chamber 21 is set within a junction area 23. The junction area 23 surrounds all sides of the holding chamber 21 apart from the side where (in the illustrated embodiment) the holding chamber 21 meets the collection chamber 16. The depth of the junction area 23 is less than the depth of the holding chamber 21, and preferably is the same or substantially the same as the depth of the collection chamber 16.

[0054] A pair of communication passages 24 extend from the joining region 23 and communicate with the exterior of the half 14 at outlet openings 32. Preferably, the outlet openings 32 of each communication passage 24 extend to the leading edge 25 of the half 14. In the illustrated embodiment, each outlet opening 32 is on the leading edge 25 in a region spaced from the inlet opening 18. The outlet openings 32 may be on the opposite side of the inlet opening 18. In the illustrated example, each outlet opening 32 is on the leading edge 25 partially along one of the angled surfaces 11 at the leading end 3.

[0055] Preferably, the two communication passages 24 are arranged symmetrically.

[0056] It is important that when the two halves 14 of the cuvette 1 are assembled, the passageway 24 provides a gas flow path from the joining region 23 to the exterior of the cuvette 1. However, the passageway 24 may communicate with the exterior of the cuvette 1 at any suitable location, for example at a side thereof, and it is not essential that the passageway 24 communicates with the front end 3. Although the depicted embodiment includes two passageways 24, in other embodiments the cuvette 1 may have a single passageway.

[0057] An analysis chamber 26 extends rearwardly from the junction area 23. The analysis chamber 26 preferably has a depth that is the same or generally the same as the depth of the collection chamber 16 and the junction area 23.

[0058] The analysis chamber 26 preferably has a consistent width along its length and has opposing sidewalls 27 that are parallel to one another. The analysis chamber 26 preferably has a constant depth along its length. The analysis chamber 26 extends towards the rear end 4 of the half 14 and terminates in a dead end (not shown in FIG. 3 ) that does not allow communication with the exterior of the cuvette 1. Thus, the analysis chamber 26 preferably communicates with the junction region 23 at its top end 28 and is otherwise enclosed on all sides. The dead end of the analysis chamber 26 preferably has a squared shape with end faces that are perpendicular or substantially perpendicular to the length of the analysis chamber 26.

[0059] Preferably, the volume of the analysis chamber 26 is larger than the volume of the collection chamber 16. In an embodiment, for example, the volume of the analysis chamber 26 may be larger than the volume of the collection chamber 16 by 5% to 15%.

[0060] FIG. 4 shows a cross-sectional view of the assembled cuvette 1. As can be clearly seen in this view, the collection chamber 16 extends rearward from the inlet opening 18 and has a consistent or substantially consistent depth along its length (the skilled reader will understand that if the recesses for forming the collection chamber 16 are formed in both halves 14, the total depth of the collection chamber 16 of the assembled cuvette 1 will be twice the depth of the recesses formed in the two halves 14). The collection chamber 16 communicates with a holding chamber 21, which has a greater depth. At its rear end, the holding chamber 21 communicates with a junction region 23, which in turn communicates with an analysis chamber 26. The junction region 23 and the analysis chamber 26 have the same depth, and in this example the boundary between these two regions 23, 26 is not visible in FIG. 4.

[0061] Figures 5a to 5d show the steps of using the cuvette 1 to take a blood sample.

[0062] As a first step, the cuvette 1 is grasped and its top 10 is brought into contact with a volume of blood. This can be obtained, for example, via a finger prick resulting in a drop of blood on a user's finger.

[0063] When the inlet opening 18 contacts blood, the blood is drawn into the inlet opening 18 by capillary action and thus into the collection chamber 16. Figure 5a shows a cross-sectional view of the interior of the cuvette 1 in the region of the holding chamber 21. In Figure 5a, a volume of blood 29 can be seen progressing along the length of the collection chamber 16. At this point, the blood 29 has not yet reached the holding chamber 21.

[0064] In order for blood 29 to be effectively drawn into collection chamber 16 by capillary action, collection chamber 16 must have an appropriate depth. As the skilled reader will appreciate, this depth will also depend on the dimensions of collection chamber 16 (particularly the length) and the material from which collection chamber 16 is made. In one example, the length of the chamber is approximately 16 mm and the chamber walls are formed from PMMA (poly(methyl methacrylate)), and a suitable depth for the chamber is between 0.5 mm and 1 mm. However, for other configurations, the chamber depth may vary. When blood 29 reaches inner end 20 of collection chamber 16, the flow of blood 29 stops at the junction of collection chamber 16 and holding chamber 21. This is caused by surface tension forces acting at the step between the relatively small depth of collection chamber 16 and the relatively large depth of holding chamber 21.

[0065] This situation is shown in Figure 5b. At this stage, the collection chamber 16 is full or substantially full of blood, but no blood has entered the holding chamber 21.

[0066] The skilled reader will appreciate that as blood flows into collection chamber 16 it displaces any air previously within collection chamber 16 and the air flows out of cuvette 1 through passageway 24 .

[0067] As a result, the user simply holds the apex 10 of the cuvette 1 in contact with a volume of blood 29, and the blood will flow through the inlet opening 18 to fill the collection chamber 16, then automatically stop flowing. Once the user has done this, the user may lift the cuvette 1 away from the volume of blood, and the collection chamber 16 will remain filled with blood. Because the blood is held in place by capillary action, it will not escape through the inlet opening 18, nor will it flow from the collection chamber 16 into the holding chamber 21 (as described above).

[0068] The cuvette 1 is therefore configured to collect a fixed, known volume of blood (ie, equal to the volume of the collection chamber 16) in an easy and reliable manner.

[0069] Once blood has been collected in this manner within collection chamber 16, cuvette 1 may be placed into a centrifuge (not shown). Cuvette 1 is placed in the centrifuge such that apex 10 of cuvette 1 is located closest to the axis of rotation, with analysis chamber 26 extending generally radially from the axis of rotation.

[0070] When centrifugal force is applied to the cuvette, the blood 29 is driven in a direction towards the rear end 4 of the cuvette 1. This force will be sufficient to overcome the surface tension forces that, up until this point, hold the leading edge of the blood 29 against the inner end 20 of the collection chamber 16. Thus, the blood 29 flows into the holding chamber 21, and then from the holding chamber 21 into the junction region 23 and into the top end 28 of the analysis chamber 26. This situation is shown in Figure 5c.

[0071] As centrifugation continues, blood 29 is driven into analysis chamber 26. As mentioned above, the volume of analysis chamber 26 is slightly larger than the volume of collection chamber 16 so that the entire sample of collected blood 29 is contained within analysis chamber 26. This leaves collection chamber 16, holding chamber 21, junction region 23 and the area at top end 28 of analysis chamber 26 free or substantially free of blood 29. This position is shown in Figure 5d.

[0072] Once the blood 29 is completely transferred into the analysis chamber 26, the blood 29 may be further centrifuged and analyzed. For example, one or more light sources may be positioned on one side of the cuvette 1 and one or more light detectors may be positioned on the same side of the cuvette 1 (to receive light from the light source by reflection) or on the opposite side of the cuvette 1 (to receive light from the light source that has been transmitted through the cuvette 1 and the blood sample).

[0073] One advantage of having the entire sample of blood drawn into collection area 16 completely contained within analysis chamber 26 is that all components of the drawn blood 29 are present within analysis chamber 26 to be analyzed. For example, a user may wish to analyze a blood sample to determine the volume of red blood cells therein as a percentage of the total sample volume. As a result of centrifugation, red blood cells (as the densest component of blood) will be forced to the bottom end of analysis chamber 26. Red blood cells absorb more light than other components of blood. The skilled reader will readily understand how analysis of other components of blood, such as white blood cells and platelets, may be performed.

[0074] All components of blood absorb light as opposed to areas where there is no blood, so by analyzing the length of the area of ​​analysis chamber 26 where the light intensity is low due to absorption by blood, the total volume of the blood sample is determined (since the depth and width of analysis chamber 26 are known), and by analyzing the length of analysis chamber 26 where light is strongly absorbed, the volume of red blood cells is determined.

[0075] As mentioned above, when blood initially flows into collection chamber 16, it stops at its inner end 20 as a result of surface tension. Figure 6 shows a close-up view of inner end 20 of collection chamber 16 where collection chamber 16 meets holding chamber 21. As can be seen in this view, collection chamber 16 communicates directly with holding chamber 21 without an intervening chamber or other feature.

[0076] 6 shows a cross-sectional side view. In this example, the front wall 33 of the holding chamber 33 (i.e., the wall closest to the collection chamber 16) is exactly or substantially perpendicular to the plane of the body 2. Thus, where the inner surface 17 of the collection chamber 16 meets the front wall 33 of the holding chamber, an angle 34 of approximately 90° is formed.

[0077] When blood 29 conforms to this angle 34, surface tension in the blood prevents the blood from passing into holding chamber 21. When blood 29 stops at inner end 20 of collection chamber 16, a recessed feature 35 may be formed that protrudes inwardly into collection chamber 16 a short distance.

[0078] The front wall 33 of the holding chamber 21 need not be perpendicular to the plane of the body 2. However, if the angle 34 is too large, the surface tension effect described above will not occur and the blood 29 will not stop at the inner end 20 of the collection chamber 16. It is believed that this effect will not occur at angles above about 135°.

[0079] It is also preferred that there be no sharp corners between the inner surface 17 of the collection chamber 16 and the front wall 33 of the holding chamber to ensure the desired surface tension effects are produced. In this regard, it is preferred to avoid rounded or chamfered corners.

[0080] The holding chamber 21 is deeper than the collection chamber 21. As shown in FIG.

[0081] The holding chamber 21 also has a length 38 in a direction generally parallel to the plane of the body 2 between its front wall 33 and the distal end of the holding chamber 21, i.e., a first feature (not shown in FIG. 6) that aligns with the holding chamber 16.

[0082] As mentioned above, FIG. 6 is a side view, i.e., a view through the depth of the cuvette 1. As seen in FIG. 3, the holding chamber 21 is also wider across the width of the body 2 than the inner end 20 of the collection chamber 16. As mentioned above, where the blood 29 stops at the inner end 20 of the collection chamber 16, it is expected that the blood 29 will form a concave shape 35. However, under certain circumstances, the blood may form a bulge that protrudes a short distance into the holding chamber. In that case, it is important that the dimensions of the holding chamber 21, particularly the step height 36 and length 38, are sufficient so that no part of the bulge contacts any part of the inner wall of the holding chamber 21.

[0083] 1 and 2, in a preferred embodiment, the major upper and lower surfaces 8, 9 of the body 2 of the cuvette 1 are formed to have a matte or textured finish. This assists in easy gripping and handling of the cuvette 1 by a user, and also makes it easier to view the otherwise transparent cuvette 1.

[0084] However, in the illustrated example, the cuvette 1 has two areas on each side that are not matte or rough, and the cuvette 1 is formed to have a generally smooth and flat surface that effectively transmits light.

[0085] The first region 30 generally resides above the collection chamber 16 and may have a shape that is the same as or similar to the shape of the collection chamber 16. This first region 30 allows a user to clearly see that blood has been successfully drawn into the cuvette 1 when the cuvette 1 is first used.

[0086] The second region 31 overlies the analysis chamber 26. This second region 31 allows for efficient analysis of the blood 29 retained in the analysis chamber 26, for example during centrifugation.

[0087] In the illustrated embodiment, the collection chamber 16 has an "hourglass" shape that tapers to a narrow point as it passes through the entrance opening 18 at the front end 3 of the cuvette 1, then flares out again to meet the holding chamber 21. In a preferred embodiment, this shape acts as a venturi constriction, which helps to accelerate the flow of blood as it is drawn from the entrance opening 18 into the front region of the collection chamber 16.

[0088] The widened portion of collection chamber 16 between its narrow point and its inner end 20 again serves to slow the flow of blood so that it moves at a relatively slower rate as it reaches the junction of collection chamber 16 and holding chamber 21, where surface tension forces ensure that it is stopped.

[0089] As mentioned above, the various chambers may be provided by recesses formed inside one or both halves of the cuvette 1. In the example shown, both halves are recessed to provide the holding chamber 21, but only one half may be recessed to provide the collection chamber 16, junction 23 and analysis chamber 26. The skilled reader will appreciate that there are many other possibilities.

[0090] It is also envisioned that a cuvette embodying the invention may have a series of internal chambers of any depth, i.e., not necessarily have a change in chamber depth that would stop blood flow via the effects of surface tension, as discussed above, but may have one or more protrusions that make the cuvette easier to pick up from a flat surface. In such an embodiment, the cuvette has a generally planar body and at least one protrusion that extends away from the body in a direction having a component that is perpendicular to the plane of the body. As a result of the protrusion, when the body is placed on a flat surface, at least a portion of the body is elevated above the surface by at least 1 cm, i.e., there is at least 1 cm of space between the body and the flat surface, allowing a user to insert a finger to easily grasp and pick up the cuvette. Any of the other features of the protrusions discussed above may also be included. The skilled reader will appreciate that a cuvette embodying the invention can be easily handled and operated by a home user, which offers significant advantages over cuvettes of known design.

[0091] As used in this specification and claims, the terms "comprises" and "comprises" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted as excluding the presence of other features, steps or components.

[0092] The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, may be expressed in their specific form, or in terms of means for performing a disclosed function, or methods or steps for achieving a disclosed result, as appropriate, and may be utilized individually or in any combination of those features to realize the invention in various of its forms.

Claims

1. A cuvette for collecting a blood sample, comprising: a body including a collection opening formed therein; a collection chamber including an inlet opening allowing communication between a first end of the collection opening and an exterior of the cuvette; a holding chamber formed within the body adjacent a second end of the collection chamber, generally opposite the first end; Including, The collection chamber has a first depth, the first depth being the same or substantially the same across the collection chamber from the first end to the second end, and the holding chamber has a second, greater depth.

2. 2. The cuvette of claim 1, wherein in the region where the collection chamber meets the holding chamber, the collection chamber is generally planar, and the holding chamber has a depth on either side of the plane of the collection chamber that is greater than a depth of the collection chamber.

3. 2. The cuvette of claim 1, wherein in a region where the collection chamber meets the holding chamber, the collection chamber is generally planar, and the holding chamber has a width in a direction generally parallel to the plane of the collection chamber, the width being greater than a width at a second end of the collection chamber.

4. The cuvette of claim 1 , wherein the collection chamber has a pair of side walls.

5. 5. The cuvette of claim 4, wherein a width of the collection chamber defined between the side walls is greater at a first end of the collection chamber than at a middle portion of the collection chamber.

6. 6. The cuvette of claim 5, wherein the width of the collection chamber is greater at the second end of the collection chamber than at the intermediate portion.

7. 2. The cuvette of claim 1, further comprising one or more communication passages, the communication passages having a first end communicating with the holding chamber and a second end communicating with an exterior of the cuvette.

8. 8. The cuvette of claim 7, comprising two communication passages.

9. 9. The cuvette of claim 8, wherein the second ends of the two communication passages are on either side of the inlet opening.

10. The cuvette of claim 1 further comprising an analysis chamber, said analysis chamber communicating at a first end with said holding chamber.

11. 11. The cuvette of claim 10, wherein the analysis chamber is surrounded on all or substantially all sides apart from its first end.

12. 11. The cuvette of claim 10, wherein the analysis chamber is elongated and has a constant or substantially constant width along its length.

13. 13. The cuvette of claim 12, wherein the analysis chamber has a constant or substantially constant width along its length.

14. 11. The cuvette of claim 10, wherein the volume of the analysis chamber is the same as or greater than the volume of the collection chamber.

15. 11. The cuvette of claim 10, further comprising a junction area adjacent to the holding chamber, the analysis chamber and one or more passageways communicating with the junction area.

16. 2. The cuvette of claim 1, wherein the dimensions of the inlet opening and collection chamber are such that when the inlet opening contacts a blood sample, blood is drawn into the collection chamber by capillary action.

17. 17. The cuvette of claim 16, wherein the dimensions of the collection chamber and holding chamber are such that blood drawn into the collection chamber by capillary action stops when it reaches the holding chamber and is no longer drawn into the holding chamber.

18. 2. The cuvette of claim 1, wherein the body is generally planar and the cuvette further includes one or more protrusions extending away from the plane of the body such that when the cuvette is placed on a flat surface, at least a portion of the body is raised above a surface a sufficient distance to allow a person to grasp the cuvette.

19. 20. The cuvette of claim 18, wherein the distance is at least 0.8 cm.

20. 20. The cuvette of claim 18, wherein a pair of protrusions are provided on opposite sides of the body.

21. 19. A cuvette according to claim 18, wherein the or each projection extends away from the plane of the body in both directions.

22. 22. A method for collecting a blood sample, comprising contacting the inlet opening of a cuvette according to any one of claims 1 to 21 with a blood sample such that blood is drawn into the collection chamber of the cuvette by capillary action to fill or substantially fill the collection chamber without substantially entering the holding chamber.

23. The cuvette is a cuvette according to claim 10, 23. The method of claim 22, further comprising subjecting the cuvette to centrifugal force to cause blood in the collection chamber to flow through the holding chamber and into the analysis chamber.

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