DETERMINING A QUANTITY OF AN ANALYTE IN A BLOOD SAMPLE

Abstract

A medical system for determining an analyte quantity in a blood sample via a cartridge that spins around a rotational axis. The cartridge may include: a separation chamber that separates blood plasma from the sample; a processing chamber containing a reagent with a specific binding partner which binds to the analyte to form an analyte specific binding partner complex; a first valve structure connecting the separation chamber to the processing chamber; a measurement structure to measure the quantity of the analyte, wherein the measurement structure includes a chromatographic membrane with an immobilized binding partner for direct or indirect binding of the analyte or the analyte specific binding partner complex, and an absorbent structure that is nearer to the axis than the membrane; a second valve structure connecting the processing chamber to the measurement structure; and a fluid chamber filled with a washing buffer and fluidically connected to the measurement structure.

Claims

1. A method of determining a quantity of an analyte in a blood sample, the method comprising: configuring a rotatable cartridge to be movably responsive about a rotational axis to rotational forces imparted thereto, the cartridge comprising a processing chamber and a measurement structure that are in selective fluid communication with one another; and upon rotation-induced separation of a blood plasma from the blood sample and subsequent formation of the blood plasma into analyte-specific binding partner complex through combination with at least one reagent contained within the processing chamber, and rotation-induced selective introduction of the analyte-specific binding partner complex and a washing buffer into the measurement structure such that both flow across a chromatographic membrane and an absorbent structure contained within the measurement structure with at least a portion of the analyte-specific binding partner complex binding to an immobilized binding partner, having the quantity of the analyte that is present at the chromatographic membrane be measured by an optical measurement system.

2. The method of claim 1, wherein the cartridge is further configured such that rotation-induced selective introduction of the analyte-specific binding partner complex and the first part of a washing buffer into the measurement structure is sequenced such that the having the quantity of the analyte that is present at the chromatographic membrane be measured by an optical measurement system takes place prior to the introduction of the first part of the washing buffer into the measurement structure.

3. The method of claim 1, wherein the cartridge is further configured to comprise a metering structure that is in selective fluid communication with the measurement structure such that the washing buffer is metered prior to being introduced into the measurement structure.

4. The method of claim 3, wherein the selective fluid communication between the processing chamber, measurement structure and metering structure is through a plurality of valve structures that are each disposed within respective tube-like structures.

5. The method of claim 4, wherein at least one of the plurality of valve structure comprises a siphon.

6. The method of claim 3, wherein the metering structure is configured to permit the washing buffer to be metered a plurality of times.

7. The method of claim 3, wherein the metering structure comprises an aliquoting chamber and a metering chamber.

8. The method of claim 7, wherein the washing buffer is contained within a fluid chamber that is in selective fluid communication with the aliquoting chamber and the metering chamber.

9. The method of claim 7, wherein rotation-induced movement of the cartridge is configured to permit a portion of the washing buffer that is present in the aliquoting chamber to fill the metering chamber such that a portion of the washing buffer is transferred from the metering chamber and into the measurement structure to flow across the membrane to the absorbent structure and then back into the aliquoting chamber before having the quantity of the analyte that is present at the chromatographic membrane be measured by an optical measurement system.

10. The method of claim 9, wherein the rotation-induced movement of the cartridge is configured to permit the washing buffer to be transferred between the metering structure and the measurement structure multiple times.

11. The method of claim 7, wherein the metering chamber is configured to be filled using capillary action.

12. The method of claim 1, wherein the at least one reagent comprises at least a binding reagent and a marking reagent.

13. The method of claim 12, wherein the processing chamber comprises a plurality of sub-processing chambers each configured to contain a different one of the binding reagent and the marking reagent.

14. The method of claim 1, wherein the cartridge is further configured to be cooperative with a cartridge spinner for rotation-induced movement of the cartridge about the rotational axis.

15. The method of claim 14, wherein the cartridge and the cartridge spinner are further configured to be responsive to a controller comprising a memory for storing machine executable instructions and a processor cooperative with one another such that execution by the processor of the machine executable instructions causes the controller to provide the rotation-induced movement of the cartridge about the rotational axis.

16. The method of claim 15, wherein the cartridge is further configured to comprise a seal responsive to the controller to enable at least a part of the washing buffer to be selectively delivered to the measurement structure.

17. The method of claim 15, wherein the execution by the processor of the machine executable instructions causes the controller to operate the optical measurement system.

18. The method of claim 17, wherein the optical measurement system comprises a colorimetric analysis system.

19. A method of determining a quantity of an analyte in a blood sample using a cartridge, wherein the cartridge is operable for being spun around a rotational axis, wherein the cartridge comprises: an inlet for receiving the blood sample; a blood separation chamber for separating blood plasma from the blood sample, wherein the blood separation chamber is fluidically connected to the inlet; a processing chamber containing at least one reagent comprising at least one specific binding partner which is operable to bind to the analyte to form at least one analyte specific binding partner complex; a first valve structure connecting the blood separation chamber to the processing chamber; a measurement structure for enabling measurement of the quantity of the analyte, wherein the measurement structure comprises a chromatographic membrane, wherein the chromatographic membrane comprises an immobilized binding partner for direct or indirect binding of the analyte or the at least one analyte specific binding partner complex, wherein the measurement structure further comprises an absorbent structure, wherein the absorbent structure is nearer to the rotational axis than the membrane; a second valve structure connecting the processing chamber to the measurement structure; a fluid chamber filled with a washing buffer, wherein the fluid chamber is fluidically connected to the measurement structure, wherein a seal keeps the washing buffer within the fluid chamber; an aliquoting chamber; a fluid duct connecting the fluid chamber with the aliquoting chamber; a metering chamber; a connecting duct which fluidically connects the metering chamber with the aliquoting chamber, wherein the measurement structure is connected to the metering chamber via a third valve structure; and a vent connected to the metering chamber, wherein the vent is nearer to the rotational axis than the metering chamber; wherein the method comprises: placing the blood sample into the inlet; rotating the cartridge about the rotational axis to transport the blood sample into the blood separation chamber; controlling the rotation of the cartridge about the rotational axis to separate the blood plasma from corpuscular blood sample components by centrifugation; opening the first valve structure and rotating the cartridge about the rotational axis to transport a defined portion of the blood plasma from the blood separation chamber to the processing chamber; holding the portion of the blood plasma in the processing chamber, wherein the blood plasma mixes with the reagent and combines with the at least one specific binding partner to form the at least one analyte specific binding partner complex; releasing the seal to enable a first part of the washing buffer to enter the measurement structure, wherein the step of releasing the seal enables the washing buffer to enter the aliquoting chamber; controlling the rotational rate of the cartridge to permit the washing buffer in the aliquoting chamber to transfer into the connecting duct and to fill the metering chamber a first time; opening the second valve structure to transfer the at least one analyte specific binding partner complex to the measurement structure and controlling the rotational rate of the cartridge to allow the at least one analyte specific binding partner complex to flow to the measurement structure through the second valve structure; controlling the rotational rate of the cartridge to allow the at least one analyte specific binding partner complex to flow across the membrane to the absorbent structure at a defined velocity and to allow the at least one analyte specific binding partner complex to bind to the immobilized binding partner; controlling the rotational rate of the cartridge to transfer the first part of the washing buffer from the metering chamber through the valve into the measurement structure and to transfer a first remaining part back into the aliquoting chamber; controlling the rotational rate of the cartridge to allow the first part of the washing buffer to flow across the membrane to the absorbent structure at a defined velocity; controlling the rotational rate of the cartridge to allow the washing buffer in the aliquoting chamber to transfer into the connecting duct and to fill the metering chamber a second time; controlling the rotational rate of the cartridge to transfer a second part of the washing buffer from the metering chamber through the valve into the measurement structure and to transfer a second remaining part back into the aliquoting chamber; controlling the rotational rate of the cartridge to allow the second part of the washing buffer to flow across the membrane to the absorbent structure; and measuring the quantity of the analyte using the membrane and using an optical measurement system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] In the following embodiments of the invention are explained in greater detail, by way of example only, making reference to the drawings in which:

[0078] FIG. 1 illustrates an example of a cartridge;

[0079] FIG. 2 shows a further view of the cartridge of FIG. 1;

[0080] FIG. 3 shows a further view of the cartridge of FIG. 1;

[0081] FIG. 4 shows an alternative to the components illustrated in FIG. 3;

[0082] FIG. 5 shows an alternative to the processing chamber of the illustrated in FIG. 1;

[0083] FIG. 6 shows a symbolic diagram which illustrates the principle of how the quantitative analyte can be determined using the cartridge;

[0084] FIG. 7 illustrates an example of an automatic analyzer;

[0085] FIG. 8 shows a flow chart which illustrates a method of operating the automatic analyzer of FIG. 7;

[0086] FIGS. 9a, 9b and 9c illustrate graphically a method determining a quantity of analyte in a blood sample using the cartridge of FIG. 1;

[0087] FIG. 10 illustrates a metering structure for performing multiple aliquots of a fluid;

[0088] FIG. 11 illustrates a cross sectional view of a metering chamber;

[0089] FIG. 12 illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 10;

[0090] FIG. 13 further illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 10;

[0091] FIG. 14 further illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 10;

[0092] FIG. 15 further illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 10;

[0093] FIG. 16 further illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 10;

[0094] FIG. 17 further illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 10;

[0095] FIG. 18 further illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 10;

[0096] FIG. 19 illustrates an alternative metering structure for performing multiple aliquots of a fluid;

[0097] FIG. 20 illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 19;

[0098] FIG. 21 further illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 19;

[0099] FIG. 22 further illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 19;

[0100] FIG. 23 further illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 19;

[0101] FIG. 24 further illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 19;

[0102] FIG. 25 further illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 19; and

[0103] FIG. 26 further illustrates part of a method of performing a dispensing fluid using the metering structure of FIG. 19.

DETAILED DESCRIPTION

[0104] Like numbered elements in these figures are either equivalent elements or perform the same function. Elements which have been discussed previously will not necessarily be discussed in later figures if the function is equivalent.

[0105] FIGS. 1 and 2 show an example of a cartridge 100. FIG. 1 shows a front view of the cartridge 100. FIG. 2 shows a backside view of the cartridge 100. The cartridge is adapted for rotating around a rotational axis 102. The cartridge 100 is predominantly flat and has an outer edge perpendicular to the rotational axis 102. The outer edge 104 is less than a particular radius and is predominantly circular in shape. In the embodiment shown in FIGS. 1 and 2 there are also several optional flat portions 106 of the outer edge. These may aid in gripping or storing the cartridge 100. In alternative embodiments such flat portions are lacking and the overall outer edge of the cartridge is predominantly circular in shape. The cartridge 100 could for example be made out of molded plastic. There may be a cover which is placed on the surface of the structure shown in FIG. 1. The cover is not shown so as to aid the view of the microfluidic structure within the cartridge 100.

[0106] The cartridge 100 is shown as having a blood inlet 108 where a blood sample can be added or pipetted into the cartridge 100. The blood inlet 108 may for example comprise a storage chamber 110 for storing a volume of a blood sample. The storage chamber 110 is shown as having an expansion chamber 112 with a vent 114. The various microfluidic structures may be shown as having expansion chambers 112 and vents 114 also. There may also be failsafe indicators 116 which are regions of the microfluidic structure which fill with fluid to indicate that a microfluidic structure has received a sufficient amount of fluid or sample. These for example may be checked optically during the use of the cartridge 100. These in some cases are labeled but are not discussed herein. The blood inlet 108 is shown as being fluidically connected to a blood separation chamber 118. The blood separation chamber 118 is used to separate the plasma from the corpuscular blood sample components (blood cells) in a blood sample. The blood separation chamber 118 is shown as also being connected to an overflow chamber 120 that accepts an excess of plasma from the blood sample. The functioning of the blood separation chamber 118 will be described in more detail below. The blood separation chamber 118 is connected to a processing chamber 124 via a first valve structure 122.

[0107] In this example the first valve structure 122 is a siphon. It could however include other structures such as a mechanical, magnetic, or thermally activated valve. The processing chamber 124 is shown as containing several surfaces 126 which could be used for storing a dry reagent. In other examples there may be amounts of liquid or other types of reagent which can be mixed with a plasma sample. The processing chamber 124 is shown as being connected to a measurement structure 130 via a second valve structure 128. In this example the second valve structure 128 is a siphon. The second valve structure 128 could take any of the forms that the first valve structure 122 can also take. In this example the processing chamber 124 is shown as being a single chamber. In another example the processing chamber 124 may comprise several sub-chambers so that a plasma sample can be processed by different reagents sequentially. The measurement structure 130 is shown as containing a chromatographic membrane 134 and in contact with the rotational axis-nearer end of the chromatographic membrane an additional absorbent structure 132 which serves as a waste fleece. The reagents and the chromatographic membrane 134 are discussed in greater detail below.

[0108] After being processed with a reagent the plasma sample may be wicked or transported across the chromatographic membrane 134. Before and/or after a washing buffer may be used to prime or wash the chromatographic membrane 134. The cartridge 100 shown in FIGS. 1 and 2 is a cartridge which incorporates a number of distinct optional features. On the backside of the cartridge 100 is shown a fluid chamber 136. In this example the fluid chamber 136 is a blister pack or flexible fluid chamber which can be compressed from outside of the cartridge 100. When the fluid chamber 136 is compressed a seal is broken which allows fluid within the fluid chamber 136 to enter a fluid duct 138. The fluid duct 138 then transports fluid to a metering structure 140.

[0109] The metering structure 140 enables the washing buffer to be supplied to the measurement structure 130 multiple times in precisely measured amounts. The metering structure 140 is however not necessary. There may be examples where the washing buffer is delivered directly to the measurement structure 130. In other examples the measurement structure is not primed with the washing buffer before the test is performed. The structure labeled 136′ is an alternate fluid chamber. The fluid chamber 136′ may be mechanically actuated to break a seal around its perimeter which causes fluid to enter the metering structure 140 via the fluid duct 138′. The cartridge 100 is also shown as containing another optional structure. The structure labeled 142 is a manual fill location where a reagent or buffer solution may be added manually to the measurement structure 130 or by an external source like a dispenser.

[0110] The metering structure 140 is shown as containing an aliquoting chamber 144. The aliquoting chamber 144 receives the fluid from the fluid chamber 136 or 136′. The aliquoting chamber 144 is connected to a metering chamber 146 via a connecting duct 148. The metering structure 146 is used to accurately meter the buffer fluid and supply metered aliquots of the fluid one or more times to the measurement structure 130. The metering structure 146 is connected to the measurement structure 130 via a fluidic element 150. In this case the fluidic element 150 is shown as containing a microfluidic duct or channel and a chamber for holding a quantity of the buffer fluid as it is being metered. The function of the metering structure 140 and several alternatives will be discussed with reference to later Figs.

[0111] FIG. 3 shows an enlarged region of FIG. 1 which illustrates the blood separation chamber 118 and the processing chamber 124 in greater detail. The separation chamber 118 is shown as containing an upper portion 300 and a lower portion 302. The upper portion 300 is closer to the rotational axis 102. The overflow chamber is shown as having an overflow opening 304. The overflow opening 304 sets the maximum volume of fluid within the blood separation chamber 118. In this example the first valve structure 122 is a siphon. It may also be referred to as a first siphon. The first siphon 122 has a siphon entrance 306 in the blood separation chamber 118. The first siphon 122 also has a siphon exit 308 into the expansion chamber 112′. In this example there is an additional expansion chamber 112′ located between the blood separation chamber 118 and the processing chamber 124. In other examples the siphon exit 308 may be directly connected to the processing chamber 124.

[0112] The expansion chamber 112 enables the processing chamber 124 to be located further from the rotational axis. This may in some instances provide additional space for the processing chamber 124. In examining FIG. 3 it can be seen that the siphon exit 308 is closer to the rotational axis 102 than the siphon entrance 306. This is done because it traps an additional amount of blood plasma within the upper portion 300. The last bit or amount of blood plasma may contain fatty or oily tissues which are contained in the blood plasma. Placing the siphon exit 308 closer to the rotational axis 102 may reduce the amount of this material in the blood plasma which is ultimately transferred to the processing chamber 124. This may result in a superior or more accurate measurement of the analyte.

[0113] It can be seen that the first siphon 122 has a nearest location 310 to the rotational axis 102. Between the nearest location 310 and the siphon exit 308 the distance to the rotational axis 102 increases monotonically.

[0114] FIG. 4 shows a further enlarged region of the cartridge 100. The region of FIG. 4 is identical to that of FIG. 3. In the example shown in FIG. 4 the first valve structure 122 and the second valve structure 128 have been modified. The first valve structure 122 comprises a valve element 400 and the second valve structure 128 comprises a valve element 402. The valve element 400 and 402 may be mechanical valves which may be opened and/or closed through a variety of means. For example the valve elements 400, 402 could be mechanically actuated, they could comprise a wax or other material which is melted by heat, as well as they could be magnetically operated, or actuated using other means.

[0115] FIG. 5 shows a modification of the cartridge 100 shown in FIG. 1. In the example shown in FIG. 5 the processing chamber 124 has been broken into two separate sub-chambers 500 and 502. The first valve structure 122 is connected to the first sub-chamber 500. There is then an intermediate valve structure 504 between the first sub-chamber 500 and the second sub-chamber 502. The second valve structure 128 is then connected from the second sub-chamber 502 to the measurement structure 130. The two sub-chambers 500, 502 can be used to process the blood plasma sequentially with different reagents.

[0116] FIG. 6 shows a symbolic diagram which illustrates the principle of how the quantitative analyte is determined using the cartridge. 600 represents a blood sample and 602 the analyte present in the blood 600. The arrow 604 represents the generation of plasma by centrifugation. 602′ represents the analyte 602 in plasma. The arrow 606 represents the mixing of plasma with a dried assay reagent and incubation in the processing chamber. Reference symbol 124 represents the processing chamber. In the processing chamber a capture antibody 608 and a detection antibody 610 attach to the analyte 602′ in the plasma. The combination of the capture antibody 608 and the detection antibody 610 with the analyte 602′ forms an analyte specific binding partner complex 611. Arrow 609 represents the transport to the measurement structure.

[0117] The arrows 612 represent the plasma transport through the chromatographic membrane 134 of the measurement structure. The three bars 614, 616 and 618 represent three different zones on the chromatographic membrane 134. Reference symbol 614 represents a capture and detection zone. Bar 616 represents an instrument control zone. Bar 618 represents an assay control zone. In the capture and detection zone 614 there may be a capture element 620 that bonds to the capture antibody 608. For example the capture element could be streptavidin and the capture antibody could be biotinylated. When the capture antibody 608 comes in contact with the capture element 620 it bonds fast to the capture antibody 608 and thereby to the complete analyte specific binding partner complex 611. The detection antibody 610 which is part of this bound analyte specific binding partner complex 611 is thereby also immobilized at this location and can then be detected later. For example the detection antibody 610 contains a fluorescent label such as fluorescent-latex. The instrument control zone 616 may contain also a latex with the fluorescent marker. This can be used to check if the optical measurement system of the instrument is functioning properly and/or to calibrate this optical measurement system. In the assay control zone 618, excess detection antibody 610 bonds to an artificial analyte line 622. The regions 616 and 618 are used as a control to ensure that the cartridge 100 and the optical measurement system of the instrument are functioning properly.

[0118] The scheme explained in FIG. 6 when used with the cartridge of FIG. 1 may in some instance provide better measurement results than when using standard laboratory methods. For example the concentration of cardiac troponin was tested using equivalent microfluidic structures in a disc. The results of these tests indicate that the accuracy and reproducibility of the measurements is superior to that obtained in a typical analytical laboratory.

[0119] In an embodiment, antibodies which can be used for the detection of human cardiac troponin T are antibodies recognizing the linear epitope ELVSLKD of human cardiac Troponin (P45379, UniProt database) which is located at the amino acid positions 129-135 of P45379 (UniProt database) or recognizing the linear epitope QQRIRNEREKE of human cardiac Troponin (P45379, UniProt database) which is located at the amino acid positions 147-157 of P45379 (UniProt database) or recognizing the linear epitope QQRIRNERE of human cardiac Troponin (P45379, UniProt database) which is located at the amino acid positions 147-155 of P45379 (UniProt database). In an embodiment, these antibodies are monoclonal mouse antibodies. In an embodiment, a combination of a first antibody recognizing the linear epitope ELVSLKD of human cardiac Troponin (P45379, UniProt database) which is located at the amino acid positions 129-135 of P45379 (UniProt database) and a second antibody recognizing either the linear epitope QQRIRNEREKE of human cardiac Troponin (P45379, UniProt database) which is located at the amino acid positions 147-157 of P45379 (UniProt database) or the linear epitope QQRIRNERE of human cardiac Troponin (P45379, UniProt database) which is located at the amino acid positions 147-155 of P45379 (UniProt database) is used to detect human cardiac Troponin T in a sandwich assay format. In another embodiment a combination of a labelled detection antibody recognizing the linear epitope ELVSLKD of human cardiac Troponin (P45379, UniProt database) which is located at the amino acid positions 129-135 of P45379 (UniProt database) and a capture antibody recognizing either the linear epitope QQRIRNEREKE of human cardiac Troponin (P45379, UniProt database) which is located at the amino acid positions 147-157 of P45379 (UniProt database) or the linear epitope QQRIRNERE of human cardiac Troponin (P45379, UniProt database) which is located at the amino acid positions 147-155 of P45379 (UniProt database) is used to detect human cardiac Troponin T in an sandwich assay format. In another embodiment, the label of the labelled detection antibody is a fluorescent latex particle.

[0120] FIG. 7 shows an example of a medical system 700. The medical system 700 is adapted for receiving a cartridge 100. There is a cartridge spinner 702 which is operable for rotating the cartridge 100 about the rotational axis. The cartridge spinner 702 has a motor 704 attached to a gripper 706 which attaches to a portion of the cartridge 708. The cartridge 100 is shown further as having a measurement or transparent structure 710. The cartridge 100 can be rotated such that the measurement structure 710 goes in front of an optical measurement system 712 which can perform for example an optical measurement of the quantity of the analyte. An actuator 711 is also shown in this figure. It can be used to open fluid reservoirs in the cartridge 100. There may also be additional actuators or mechanisms for actuating mechanical valves or valve elements on the cartridge if they are present.

[0121] The actuator 711, the cartridge spinner 702, and the measurement system 712 are shown as all being connected to a hardware interface 716 of a controller 714. The controller 714 contains a processor 718 in communication with the hardware interface 716, electronic storage 720, electronic memory 722, and a network interface 724. The electronic memory 730 has machine executable instructions which enable the processor 718 to control the operation and function of the medical system 700. The electronic storage 720 is shown as containing a measurement 732 that was acquired when instructions 730 were executed by the processor 718. The network interface 724 enables the processor 718 to send the measurement 732 via network connection 726 to a laboratory information system 728.

[0122] FIG. 8 shows a flowchart, which illustrates a method of operating the medical system 700 of FIG. 7. The steps in FIG. 8 for example may be machine-executable instructions that are included in the instructions 730. Before the method of FIG. 8 is performed a blood sample for example may be placed into the inlet and then the cartridge 100 is placed into the medical system 700. First in step 800 the processor 718 controls the motor 704 such that the cartridge is rotated about the rotational axis to transport the blood sample into the blood separation chamber. Next in step 802 the processor 718 further controls the motor 704 such that the rotation of the cartridge about the rotational axis separates the blood plasma from the corpuscular blood sample components by centrifugation. Next in step 804 the processor 718 controls the motor 704 such that the first valve structure is opened and the cartridge is rotated about the rotational axis at a sufficient velocity to transport a defined portion of the blood plasma from the blood separation chamber to the processing chamber. In the case where the valve structures comprise mechanical valve elements there may be an additional mechanism or apparatus that the processor controls 718 to open these mechanical valve elements.

[0123] Next in step 806 the processor 718 controls the rotation rate of the motor 704 such that the portion of the blood plasma is held in the processing chamber. During this time the blood plasma mixes with the reagent and combines with at least one specific binding partner to form the at least one analyte-specific binding partner complex. Next in step 808 a seal is released to enable a first part of the washing buffer to enter the measurement structure by the processor 718. For example the processor 718 may control the actuator 711 to compress the fluid chamber 136 shown in FIG. 2. Next in step 810 the processor 718 controls the rotation rate of the motor 704 such that the second valve structure is opened to transfer the at least one specific binding partner complex to the measurement structure and such that the cartridge allows the at least one analyte-specific binding partner complex to flow to the measurement structure through the second valve structure. Again if the second valve structure comprises a mechanical valve element then the processor may also control an additional apparatus or mechanism to open this mechanical valve element.

[0124] Next in step 812, the processor 718 controls the rotational rate of the motor 704 such that the cartridge allows the at least one analyte-specific binding partner complex to flow across the membrane to the absorbent structure at a defined velocity and to allow the at least one analyte-specific binding partner complex to bind to the immobilized binding partner. In step 814 the processor 718 controls the rotational rate of the motor 704 such that the cartridge spins at a rate that allows the first part of the washing buffer to flow across the membrane to the absorbent structure at a defined velocity. In alternate embodiments the step 808 (releasing the seal to enable a first part of the washing buffer to enter the measurement structure) is performed directly before step 814. Finally in step 816 the processor 718 controls the optical measurement system 712 to perform the measurement using the optical measurement system. This measurement 732 may then be transformed into an analyte quantity or concentration.

[0125] FIGS. 9A, 9B and 9C illustrate graphically a method determining a quantity of analyte in a blood sample using the cartridge 100. The method is illustrated graphically in FIGS. 9A, 9B and 9C. Image 900 shows the cartridge 100 in its initial condition. Next in step 902 blood is placed into the inlet. Next in step 904 the blood sample is transferred to the blood separation chamber. In step 906 the plasma is separated from the red blood cells by centrifugation. Next in step 908 the blood plasma is transferred to the processing chamber. Next in step 910 the blood plasma is mixed with the reagent. In step 912 the washing buffer is released by breaking the seal. In step 914 the incubate or the combination of the blood plasma and the reagent is transferred to the measurement structure.

[0126] Next in step 916 the chromatography of the analyte-specific binding partner complex or incubate is performed. Next in step 918 the washing buffer is metered. In several instances the structure depicted may be used to provide multiple meterings of the washing buffer. However, this is not necessary in all cases and it is possible that only the fluid from the fluid chamber is transferred and that there is no metering step. Next in step 920 the washing buffer is transferred to the measurement structure and wicked across the chromatographic membrane 134 into the absorbent structure 132, as shown in step 922. Finally, in step 924 the measurement of the analyte is performed using a fluorescence measurement.

[0127] FIG. 10 shows an example of a metering structure 140. The metering structure part of the fluidic components that make up a cartridge 100 as is shown in FIG. 1. There is a rotational axis labeled 102. Also shown in the Fig. is a portion of a fluid chamber 136. The fluid chamber is designed for having a reservoir that provides fluid via a fluid chamber duct 138 that leads into the aliquoting chamber 144. In this example the aliquoting chamber 144 is whale-shaped. There is a connecting duct 148 which connects the aliquoting chamber 144 with a metering chamber 146. The connecting duct 148 has a duct entrance 1014 and a duct exit 1016. The duct entrance 1014 leads to the aliquoting chamber 144 and the duct exit 1016 leads to the metering chamber 146. A circular arc 1018 that is drawn about the rotational axis 102 passes both through the duct entrance 1014 and the duct exit 1016. The metering chamber 146 is connected via a tube-like structure 1020 to a fluidic element 150. In this example there is a valve 1021 between the tube-like structure 1020 and the metering chamber 146. In this example the valve 1021 is a capillary valve.

[0128] The valve 1021 could be implemented in different ways. In some alternatives the shape of the interface between the tube-like structure 1020 and the fluidic element 150 could function as a capillary valve. Alternatively a valve could be placed between the elements 1020 and 150. In other embodiments a duct could be connected in the same location and a controllable microvalve could be used instead. The controllable microvalve could be placed between the metering chamber 146 and the tube-like structure 1020 or between the tube-like structure 1020 and the fluidic element 150.

[0129] An optional expansion chamber 1024 is shown as bordering on an upper edge 1026 of the metering chamber 146. There is a vent 1028 which vents the expansion chamber 1024. The whole boundary between the metering chamber 146 and the expansion chamber 1024 is open. This may help reduce the chances of bubbles forming in the metering chamber 146. In some examples the expansion chamber 1024 may have a width which is greater than that of the metering chamber 146. Capillary forces may be used then to keep the fluid in the metering chamber 146. The dashed line labeled 1030 and also A-A shows the location of a cross-sectional view of the metering chamber 146. This cross-sectional view is shown in FIG. 11. The aliquoting chamber 144 can be shown as also having a vent 1028. The region around the duct entrance 1014 is in this embodiment funnel-shaped. It may also be noted that the aliquoting chamber 144 is shown as not having sharp edges. The lack of sharp edges helps to facilitate the movement of fluid from the aliquoting chamber 144 to the duct entrance 1014 when the disc is decelerated.

[0130] The aliquoting chamber 144 is also shown as having a connection to a fluidic connection 1034 which leads to an excess fluid chamber 1032. The fluidic connection 1034 has a fluidic connection entrance 1036. The fluidic connection entrance 1036 defines the maximum fluid level in the aliquoting chamber 144. The maximum fluid level in the aliquoting chamber 144 is lower than the circular arc 1018. The fluidic connection 1034 is connected to the excess fluid chamber 1032 via a capillary valve 1038 in this embodiment. The use of a valve or a capillary valve is optional. The excess fluid chamber is shown as having a vent 1028 and it is also connected to a fail-safe chamber 1040. When the fluid flows into the excess fluid chamber 1032 the fail safe chamber 1040 is filled. The fail safe chamber 1040 may be used to indicate optically if fluid has entered the excess fluid chamber 1032. For example during use if the fail safe chamber 1040 is not filled it may indicate that the aliquoting chamber 144 was not properly filled with fluid.

[0131] FIG. 11 shows a cross-sectional view 100 of the profile A-A which is labeled 1030 in FIG. 10. In this Fig. the body of the cartridge 1102 can be seen. There is an opening in the body 1102 for the metering chamber 146. The body of the cartridge 1102 in this example is fabricated by injection molding. The body of the cartridge is assembled from a lid 1108 and a support structure 1110.

[0132] At the far end of the metering chamber the entrance into the valve 1021 can be seen. The metering chamber 146 can be seen as being divided into several different regions. On the edges there are two sidewalls regions 1104. Between the two sidewalls regions or two side regions is a central region 1106. The sidewall 1104 regions become more narrow or taper away from the central region 1106. This causes a narrowing in the dimensions of the metering chamber 146 in this region. The capillary action may therefore be higher in the sidewall regions 1104 than in the central region 1106. This may cause the metering chamber 146 to fill with fluid first in the sidewall regions 1104 before the central region 1106. This may have the benefit of reducing the number of bubbles which are formed or trapped in the metering chamber 146 when the metering chamber 146 is filled with fluid.

[0133] FIGS. 12-18 illustrate how the metering structure 140 may be used to perform multiple aliquotations of fluid to the fluidic elements 150.

[0134] In FIG. 12 the disc is rotated about the rotational axis 102. The arrow 1200 indicates the direction of rotation. In this particular example the disc is spinning at 20 Hz. Fluid or washing buffer 1202 is transported into the aliquoting chamber 144 from the fluid chamber 136. Fluid 1202 can be seen dripping from the fluid duct 138 into the aliquoting chamber 144. The fluid volume in the aliquoting chamber 144 is limited and thereby metered by the fluidic connection 1034 which connects to the excess fluid chamber 1032. The fail safe chamber 1040 can be seen as being filled with fluid.

[0135] Next in FIG. 13 the fluid volume 1202 has been completely transferred from the fluid chamber 136 into the aliquoting chamber 144. The fail safe chamber 1040 is shown as being filled with the fluid. In this example the disc is still spinning at the same rate as was shown in FIG. 12. The aliquoting chamber 144 is filled with fluid 1202 up to the maximum fluid level 1300. It can be seen that the maximum fluid level 1300 is below or further away from the rotational axis 102 than the connecting duct 148. When the disc is spinning in this way the fluid 1202 cannot enter the metering chamber 146.

[0136] Next in FIG. 14 the disc stops or is decelerated to a lower rotational frequency with a high rate of deceleration for example at 50 Hz per second. The inertia of the fluid forces the fluid 1202 towards and through the connecting duct 148 and into the metering chamber 146. It can be seen in this Fig. that the fluid 1202 is filling the sides of the metering chamber 146 before it is filling the central region. This is because of the tapered side walls 1104 shown in FIG. 11. Capillary action causes this side wall portion of the metering chamber 146 to fill first. This manner of filling the metering chamber may reduce the chances that air bubbles form or adhere in the metering chamber 146.

[0137] In FIG. 15 the cartridge is still stationary or at a reduced rotation rate and the metering chamber 146 is completely filled with fluid 1202. The cartridge or disc may still be considered to be at rest. The complete filling of the metering chamber is caused by capillary forces caused by the respective geometrical dimensions of the metering chamber.

[0138] FIG. 16 shows the same view as is shown in FIG. 15 except a dashed line 1600 has been drawn in the metering chamber 146. This line 1600 in the metering chamber 146 divides the fluid in the metering chamber into several parts or portions. The fluid part 1604 radially inwards (closer to rotational axis 102) from the line 1600 may flow back into the reservoir. The radially outward part (further away from the rotational axis 102) or part 1602 may be completely transferred into the fluidic elements 150. The radially inward part 1604 can be referred to as the remaining part of the fluid and the radially outward part 1602 can be referred to as the part of the fluid 1602 that is transferred into the downstream fluidic element. The volume of the fluid 1602 is the aliquot transferred in a subsequent step to the fluidic elements 150.

[0139] Next in FIG. 17 the disc begins to accelerate and spin around in the direction 1200. The disc accelerates; this causes the capillary valve 1021 to open. The remaining part of the fluid 1604 was transferred back to the aliquoting chamber 144. The part of the fluid 1602 is in the process of being transferred to the fluidic elements 150. A drop of the fluid can be seen dropping from the tube 1020.

[0140] Next in FIG. 18 it can be seen that the fluid volume 1602 has been completely transferred to the fluidic elements 150 and is no longer visible in the Fig. The remaining part of the fluid 1604 has been transferred back into the aliquoting chamber 144 and is mixed with the remaining fluid 1202. The first aliquotation step is finished; the process may be repeated again from FIG. 14 and may be repeated until the fluid volume 1202 in the aliquoting chamber 144 is smaller than the volume of the metering chamber 146.

[0141] FIG. 19 shows an example of an alternate metering structure 140′. The metering structure 140′ may replace the metering structure 140 in FIG. 1. The mechanical structure of the metering structure 140′ is similar to the metering structure 140 of FIG. 10 with several mechanical differences. Again, there is a rotational axis labeled 102. Also shown in the Fig. is a portion of a fluid chamber 136. The fluid chamber 136 has a reservoir that provides fluid via a fluid chamber duct 138 that leads into the aliquoting chamber 144. In this example the aliquoting chamber 144 is teapot-shaped. There is a connecting duct 148 which connects the aliquoting chamber 144 with a metering chamber 146. The connecting duct 148 has a duct entrance 1014 and a duct exit 1016. The duct entrance 1014 leads to the aliquoting chamber 144 and the duct exit 1016 leads to the metering chamber 146. The duct entrance 1014 is further away from the rotational axis 102 than the duct exit 1016 of the connecting duct 148 is.

[0142] The metering chamber 146 is connected via a tube-like structure 1020 to fluidic element 150. In this example there is a valve 1021 between the tube-like structure 1020 and the fluidic elements. The valve 1021 in this example is a capillary valve. The valve 1021 could be implemented in different ways. In some embodiments the tube-like structure 1020 could functions as the capillary valve. In some embodiments a duct could be connected in the same location and a controllable microvalve could be used instead. The controllable microvalve could be placed between the metering chamber 146 and the tube-like structure 1020 or between the tube-like structure 1020 and the fluidic elements 150.

[0143] An expansion chamber 1024 is shown as bordering on an upper edge 1026 of the metering chamber 146. There is a vent 1028 which vents the expansion chamber 1024. The whole boundary between the metering chamber 146 and the expansion chamber 1024 is open. This may help reduce the chances of bubbles forming in the metering chamber 146. In some examples the expansion chamber 1024 may have a width which is greater than that of the metering chamber 146. Capillary forces may be used then to keep the fluid in the metering chamber 146. The dashed line labeled 1030 and also A-A shows the location of a cross-sectional view of the metering chamber 112. The cross section A-A 1030 is equivalent to the cross section A-A in FIG. 10. The details described with respect to FIG. 11 also apply to the cross section A-A in FIG. 19.

[0144] The aliquoting chamber 144 can be shown as also having a vent 1028. The region around the duct entrance 1014 is in this embodiment funnel-shaped. It may also be noted that the aliquoting chamber 144 is shown as not having sharp edges. The lack of sharp edges helps to facilitate the movement of fluid from the aliquoting chamber 144 to the duct entrance 1014 when the disc is decelerated.

[0145] The aliquoting chamber 144 is also shown as having a connection to a fluidic connection 1034 which leads to an excess fluid chamber 1032. The fluidic connection 1034 has a fluidic connection entrance 1036. The fluidic connection entrance 1036 defines the maximum fluid level in the aliquoting chamber 144. The maximum fluid level in the aliquoting chamber 144 is further from the rotational axis 102 than the duct exit 1016. The fluidic connection 1034 is connected to the excess fluid chamber 1032 in this example. The use of a valve or a capillary valve is optional. The excess fluid chamber is shown as having a vent 1028 and it is also connected to a fail-safe chamber 1040. When the fluid flows into the excess fluid chamber 1032 the fail safe 1040 chamber is filled. The fail safe chamber 1040 may be used to indicate optically if fluid has entered the excess fluid chamber 1032. For example during use if the fail safe chamber 1040 is not filled it may indicate that the aliquoting chamber 144 was not properly filled with fluid.

[0146] FIGS. 20-26 illustrate how the metering structure 140′ may be used to perform multiple aliquotations of fluid to fluidic element 150.

[0147] First in FIG. 20 fluid has been added to the fluid chamber 136. The cartridge is then spun about the rotational axis 102, which forces fluid or washing buffer 1202 to travel through the first duct 106 into the aliquoting chamber 144. The fluid 1202 then fills the aliquoting chamber 144 and the corresponding radially outwards portion of the connecting duct 148 with fluid.

[0148] FIG. 21 shows the cartridge spinning at the same rate and same direction 1200 as was shown in FIG. 20. In FIG. 21 all the fluid has been drained out of the fluid chamber 136. The fluid 1202 can be shown as filling the connecting duct 148 and the aliquoting chamber 144 to the maximum fluid level 1300 which is set by the fluid connection entrance 1036. Excess fluid 1202 can be shown as being filled into the excess fluid chamber 1032 and the fail safe chamber 1040.

[0149] Next in FIG. 22 the disc stops or is decelerated to a lower rotational frequency. Capillary action in the connecting duct 148 and the metering chamber 146 is shown as beginning to draw fluid into the metering chamber 146. The fluid 1202 first fills the periphery or edge of the metering chamber 146. This is because of the tapered side walls 1104 shown in FIG. 11. Capillary action causes the side wall portion of the metering chamber 146 to fill first. This helps preventing the formation or adhesion of bubbles within the metering chamber 146. When the cartridge is rapidly de-accelerated inertia of the fluid 1202 may also help it to enter the metering chamber 146.

[0150] Next in FIG. 23 the cartridge is shown as being still stationary or at a reduced rotation rate and the metering chamber 146 is completely filled with fluid 1202. The cartridge or disc may still be considered to be at rest.

[0151] FIG. 24 shows the same view as is shown in FIG. 23 except a dashed line 1600 has been drawn in the metering chamber 146. This line 1600 in the metering chamber 146 divides the fluid in the metering chamber into several parts or portions. A part of the fluid volume or the whole fluid volume 1604 radially inwards (closer to the rotational axis 102) from the line 1600 may flow back into the reservoir. The radially outwards part (further away from the rotational axis 102) or part 1602 may be transferred into the fluidic element 150. The radially inward part 1604 can be referred to as the remaining part of the fluid and the radially outward part 1602 can be referred to as the part of the fluid 1602 that is transferred into the fluidic elements 150. The volume of the fluid 1602 is the aliquot.

[0152] Next in FIG. 25 the disc begins to accelerate and spin around in the direction 1200. The disc accelerates; this causes the capillary valve 1021 to open. The remaining part of the fluid 1604 was transferred back to the aliquoting chamber 144. The part of the fluid 1602 is in the process of being transferred to the downstream fluidic element 150. A drop of the fluid 1202 can be seen dropping from the tube-like structure 1020.

[0153] Next in FIG. 26 it can be seen that the fluid volume 1602 has been completely transferred to the fluidic elements 150 and is no longer visible in FIG. 26. The remaining part of the fluid 1604 has been transferred back into the aliquoting chamber 144 and is mixed with the remaining fluid 1202. The first aliquotation step is finished; the process may be repeated again from FIG. 22 and may be repeated until the fluid volume 1202 in the aliquoting chamber 144 is smaller than the volume of the metering chamber 146.

LIST OF REFERENCE NUMERALS

[0154] 100 cartridge [0155] 102 rotational axis [0156] 104 circular outer edge [0157] 106 flat outer edge [0158] 108 blood inlet [0159] 110 storage chamber [0160] 112 expansion chamber [0161] 112′ expansion chamber [0162] 114 vent [0163] 116 failsafe indicators [0164] 118 blood separation chamber [0165] 120 overflow chamber [0166] 122 first valve structure [0167] 124 processing chamber [0168] 126 surface for reagent [0169] 128 second valve structure [0170] 130 measurement structure [0171] 132 absorbent structure [0172] 134 chromatographic membrane [0173] 136 fluid chamber [0174] 136′ fluid chamber [0175] 138 fluid duct [0176] 138′ fluid duct [0177] 140 metering structure [0178] 140′ metering structure [0179] 142 manual fill location [0180] 144 aliquoting chamber [0181] 146 metering chamber [0182] 148 connecting duct [0183] 150 fluidic element [0184] 300 upper portion [0185] 302 lower portion [0186] 304 overflow opening [0187] 306 siphon entrance [0188] 308 siphon exit [0189] 310 nearest location [0190] 400 valve element [0191] 402 valve element [0192] 500 first sub chamber [0193] 502 second sub chamber [0194] 504 intermediate valve structure [0195] 600 blood [0196] 602 analyte in blood [0197] 602′ analyte in plasma [0198] 604 plasma generation [0199] 606 mixing plasma with dried assay reagents and incubation in processing chamber [0200] 608 capture antibody [0201] 609 transport to measurement structure [0202] 610 detection antibody [0203] 611 analyte specific binding partner complex. [0204] 612 motion of plasma across membrane [0205] 614 capture and detection zone [0206] 616 instrument control zone [0207] 618 assay control zone [0208] 620 capture element [0209] 622 artificial analyte line [0210] 700 medical system [0211] 702 cartridge spinner [0212] 704 motor [0213] 706 gripper [0214] 708 portion of cartridge [0215] 710 measurement structure [0216] 711 actuator [0217] 712 optical measurement system [0218] 714 controller [0219] 716 hardware interface [0220] 718 processor [0221] 720 electronic storage [0222] 722 electronic memory [0223] 724 network interface [0224] 726 network connection [0225] 728 laboratory information system [0226] 730 executable instructions [0227] 732 measurement [0228] 800 rotating the cartridge about the rotational axis to transport the blood sample into the blood separation chamber [0229] 802 controlling the rotation of the cartridge about the rotational axis to separate the blood plasma from the corpuscular blood sample components by centrifugation [0230] 804 opening the first valve structure and rotating the cartridge about the rotational axis to transport a defined portion of the blood plasma from the blood separation chamber to the processing chamber [0231] 806 holding the portion of the blood plasma in the processing chamber [0232] 808 releasing the seal to enable a first part of the washing buffer to enter the measurement structure [0233] 810 opening the second valve structure to transfer the at least one specific binding partner complex to the measurement structure and controlling the rotational rate of the cartridge to allow the at least one analyte specific binding partner complex to flow to the measurement structure through the second valve structure [0234] 812 controlling the rotational rate of the cartridge to allow the at least one analyte specific binding partner complex to flow across the membrane to the absorbent structure at a defined velocity and to allow the at least one analyte specific binding partner complex to bind to the immobilized binding partner [0235] 814 controlling the rotational rate of the cartridge to allow the first part of the washing buffer to flow across the membrane to the absorbent structure at a defined velocity [0236] 816 performing the measurement using the membrane and using an optical measurement system for the analyte quantization [0237] 900 cartridge in initial condition [0238] 902 place blood into inlet [0239] 904 transfer of sample to blood separation chamber [0240] 906 plasma separation by centrifugation [0241] 908 transfer blood plasma to processing chamber [0242] 910 mix blood plasma with reagent [0243] 912 release of wash buffer [0244] 914 transfer incubate to measurement structure [0245] 916 chromatography of analyte specific binding partner complex [0246] 918 metering of wash buffer [0247] 920 transfer of wash buffer [0248] 922 chromatography of wash buffer [0249] 924 measurement of analyte [0250] 1014 duct entrance [0251] 1016 duct exit [0252] 1018 circular arc [0253] 1020 tube-like structure [0254] 1021 valve [0255] 1024 expansion chamber [0256] 1026 upper edge [0257] 1028 vent [0258] 1030 profile A-A [0259] 1032 excess fluid chamber [0260] 1034 fluidic connection [0261] 1036 fluidic connection entrance [0262] 1038 capillary valve [0263] 1040 fail safe chamber [0264] 1100 cross sectional view A-A [0265] 1102 body of cartridge [0266] 1104 side walls [0267] 1106 central region [0268] 1108 lid [0269] 1110 support structure [0270] 1200 direction of rotation [0271] 1202 fluid [0272] 1300 maximum fluid level [0273] 1600 dividing line [0274] 1602 part of fluid [0275] 1604 remaining part of fluid