Field of the invention

[0001] The present invention concerns simplified assemblies, which have less parts compared to prior art assemblies, but which can still allow a plurality of sample fluids to be consecutively flowed through flow cells in rapid succession, thereby allowing screening of said plurality of sample fluids in rapid succession. There is further provided corresponding methods for screening a plurality of sample fluids.

Description of related art

[0002] Fluidic assemblies for biosensing applications typically comprise a flow cell. As is well recognized in the art, a flow cell is a solid support having a microfluidic channel defined therein; and at least a portion of the surface which defines the microfluidic channel defines a test surface which can be probed using a sensor. The test surface is adapted to receive ligands through immobilization; once immobilized or captured on the test surface, the ligands can bind to predefined molecules. Sample fluids are passed through the flow cell and if said predefined molecules are present in that sample fluid they will become bound to the ligands within the flow cell. Thus it can be determined if a sample fluid contains the predefined molecule by passing the sample fluid through the flow cell and detecting if the ligands in the flow cell have bound to molecules as the sample fluid flows through the flow cell. Alternatively, if the sample fluid contains known concentrations of the predefined molecules, the kinetics of the molecular binding between the ligands and predefined molecules can be analysed. Typically it will be desired to consecutively screen a plurality of sample fluids; for each sample fluid it will need to be picked up, using a hollow needle for example, and then passed through the flow cell; then the needle (and flow cell) must be cleaned before the next sample fluid is screened. [0003] A major drawback of existing screening assemblies and methods for screening a plurality of different sample fluids, is the cycle time, i.e. the time elapsed from the start of the injection of one sample fluid from a needle into a flow cell, to the start of the injection of a next sample into the flow cell, is limited by the time it takes to wash after the first sample and the time it takes to pick up the next sample fluid. The combined pickup and wash times are typically in the order of one to two minutes. With the addition of other necessary steps, such as the need for an equilibrating baseline buffer injection prior to injection, the maximum throughput that such a device can obtain is in the order of 2Ό00-4Ό00 samples per day.

[0004] Attempts to resolve this problem by been made by simple parallelization, parallel injections of sample fluids into different flow cells. However, the different flow cells may have different characteristics, e.g. different target immobilization levels, thus leading to results which are not comparable. Also, such parallelization often requires the use of one syringe per needle to pick up the sample fluids; this leave to high manufacturing costs, and larger instrument size, and the risk of trapping air in a pump due to incomplete syringe pump priming is increased, and the buffer

consumption for operating these devices is very high, requiring large buffer tanks and or frequent buffer change.

[0005] It is an aim of the present invention to obviate, or at least mitigate, one or more of the above-mentioned disadvantages.

Brief summary of the invention

[0006] According to the invention, these aims are achieved by means of an assembly and/or method having the features recited in the independent claims; wherein the dependent claims recite optional features of preferred embodiments. Brief Description of the Drawings

[0007] The invention will be better understood with the aid of the description of an embodiment given by way of example and illustrated by the figures, in which: Fig. 1 shows an assembly according to an embodiment of the present invention;

Fig. 2 shows an assembly according to a further embodiment of the present invention.

Fig. 3a provides a perspective view of a portion of a disposable cartridge and Fig. 3b provides a perspective view of a plunger assembly, wherein the disposable cartridge and plunger assembly can mechanically cooperate with one another;

Fig. 4 provides the bottom view of a disposable cartridge, which can contain the flow cells which make up cell unit in any of the assemblies of Fig. 1 or 2.

Detailed Description of possible embodiments of the Invention

[0008] Figure 1 illustrates an assembly 101 according to one

embodiment of the present invention. The assembly 100 is suitable for high throughput biochemical sensing, for instance screening for unknown molecules having a high affinity towards the ligands, or detection or quantification of known molecules at unknown concentrations in a sample fluids binding to the ligands. Examples include testing small molecule drug candidate binding to a drug target, such as screening of a pharmaceutical compound library; or Fragment Based Screening. [0009] The assembly 100 comprises, a needle unit 2, a flow cell unit 3, a first selector valve unit 4, a second selector valve unit 6, and a pumping means 12. The assembly 100 further comprises the optional feature of a sample holder tray 1.

[0010] The sample holder tray 1 comprises a plurality of sample reservoirs 1', specifically the sample holder tray 1 comprises consecutive rows of reservoirs, each row comprising eight reservoirs 1a-h. The sample holder tray 1 s typically in the form of a micro well plate, such as industry standard 96-well or 384-well micro titer plates, or in the form of a plurality of vials. The reservoirs 1' of the sample holder tray 1 are typically filled with samples which are to be screened; the reservoirs can be filled manually or by means of an automated liquid handling station. Typically, each reservoir 1' is sealed by means of a foil, or by means of a septum in case of vials, in order to avoid concentration mismatches due to evaporation, and to avoid mixing and/or contamination of the sample fluids in each reservoir 1'. In the assembly 100 shown I figure 1 the sample holder tray 1 is defined by a 96-well micro titer plate (known in the art), containing twelve rows of eight reservoirs 1 a-h. Each row comprises a first reservoir 1 a, a second reservoirl b, a third reservoir 1c, a fourth reservoir 1 d, a fifth reservoir 1e, a sixth reservoir 1f, a seventh reservoir 1 g, and an eighth reservoir 1 h.

[0011] The needle unit 2 comprises n hollow needles 2a-h, wherein n is greater than one. In this particular example n is equal to eight so needle unit 2 comprises eight hollow needles 2a-h; specifically the needle unit 2 comprises a first hollow needle 2a, a second hollow needle 2b, a third hollow needle 2c, a fourth hollow needle 2d, a fifth hollow needle 2e, a sixth hollow needle 2f, a seventh hollow needle 2g, and an eight hollow needle 2h. However it should be understood that n many have any value greater than one; for example in another embodiment the needle unit 2 may comprise less needles than eight needles, such as for example four needles, or preferably more than eight needles such as sixteen or thirty- two, or sixty-four, or ninety-six needles.

[0012] The hollow needles in the needle unit 2 are typically in the form of a conduit with an opening at the bottom, such as a stainless-steel needle or a PEEK tube with a bottom opening. Preferably, the needles are rigid allowing them to be able to pierce a foil or a septum which may (which may cover reservoirs in the sample holder tray 1). Preferably the needle unit 2 can be selectively moved with respect to the sample holder tray 1 e.g. moved to dip the hollow needles into the reservoirs 1' in the sample holder tray 1 (in this case the sample holder tray 1 may be kept stationary); the movement of the needle unit 2 is typically achieved by means of a robotic arm or xyz-table on which the needle unit 2 is mounted (alternatively the needle unit 2 may be kept stationary and the sample holder tray 1 may be moved relative to the needle unit 2 using a robotic arm or xyz table).

[0013] The flow cell unit 3 comprises m flow cells 3a-d, wherein m is greater than one. In this example m is equal to four so that flow cell unit 3 comprises four flow cells 3a-3d, namely a first flow cell 3a, a second flow cell 3b, a third flow cell 3c and a fourth flow cell 3d. However, it should be understood that m many have any value greater than one (for example the flow cell unit 3 may comprise two flow cells or three flow cells, or eight flow cells, or nine flow cells, or ten flow cells, or twelve flow cells, or sixteen flow cells, or twenty flow cells, or twenty-four flow cells or thirty- two flow cells). Each flow cell 3a-d has a respective input 3a'-3d'and an respective output 3a"-3d", and a test surface on which ligands can be provided located between its respective input 3a'-3d' and output 3a"-3d". As is well recognized in the art, a flow cell is a solid support having a fluidic channel (preferably a microfluidic channel) defined therein; and at least a portion of the surface which defines the fluidic channel defines the test surface which can be probed using a sensor.

[0014] The ligands are preferably captured or immobilized on the respective test surfaces using amine coupling within a thin hydrogel layer such as a Dextran layer covalently bound to the surface within a flow cell; in another preferred embodiment the ligands are captured by a suitable tag (such as biotin or hexahistidine or glutathione-S-transferase within a gel matrix such as Agarose) which is provides on the test surface of the flow cell. [0015] Preferably the assembly 101 further comprises a sensor 103' which can detect if molecules of a sample fluid which has flowed through one or more of the m flow cells 3a-d, have become bound to ligands on the test surface(s) of said one or more flow cells 3a-d. The sensor 103' may take any suitable form, for example the sensor 103' may comprise a Surface Plasmon Resonance sensor, or, Waveguide interferometry sensor, or surface acoustic sensor, or potentiometric sensor, which is configured to measure if molecules have become bound to the ligands on the test surface of a flow cell 3a-d of the flow cell unit 3. The sensor 103' is preferably operably connected to the flow cell unit 3 so that it can perform such measurements, and preferably provides a time-resolved signal indicative of a physical change near the test surface, such as refractive index changes or changes in charge potential, such physical change being induced by the presence of said predefined molecule. Predefined molecules bind to predefined ligands; therefore if a flow cell has a predefined ligand on its test surface, that ligand being known to bind with a predefined molecule, if after a sample fluid has flowed through the flow cell the sensor 103' indicates that the molecules of that flow cell have become bound to said ligands, this indicates that the sample fluid contained said predefined molecule. In this way the presence (or absence) of predefined molecules in a sample fluid can be determined. Alternatively, if a flow cell has a predefined ligand on its test surface, and that ligand being known or suspected to bind with a predefined molecule, the kinetics and/or affinity of the molecular binding between that ligand and said predefined molecule can be characterized by fitting an appropriate interaction model to the response of the sensor 103' over time, such response having been obtained when flowing several sample fluids containing different concentrations of said predefined molecule through the flow cell and over said test surface. It should be understood that in the present application, if a fluid is said to flow through a flow cell, this means that said fluid has flowed over the test surface of said flow cell.

[0016] The first selector valve unit 4 has a single output 4' which is fluidly connected to the m flow cells 3a-d in the flow cell unit 3; specifically the single output 4' of the first selector valve unit 4 is fluidly connected to all of the inputs 3a'-3d' of all of the m flow cells 3a-d in the flow cell unit 3.

[0017] The first selector valve unit 4 has n inputs 4a-h (i.e. the number of inputs 4a-h which the first selector valve unit 4 has corresponds to the number of hollow needles in the needle unit 2). As mentioned in this example n is equal to eight therefore the first selector valve unit 4 has eight inputs 4a-h (namely a first input 4a, second input 4b, third input 4c, fourth input 4d, fifth input 4e, sixth input 4f, seventh input 4g, eight input 4h). The first input 4a is fluidly connected to the first hollow needle 2a; the second input 4b is fluidly connected to the second hollow needle 2b; the third input 4c is fluidly connected to the third hollow needle 2c; the fourth input 4d is fluidly connected to the fourth hollow needle 2d; the fifth input 4e is fluidly connected to the fifth hollow needle 2e; the sixth input 4f is fluidly connected to the sixth hollow needle 2f; the seventh input 4g is fluidly connected to the seventh hollow needle 2g; and the eight input 4h is fluidly connected to the eight hollow needle 2h.

[0018] The first selector valve unit is configured such that it can selectively fluidly connect any one or more of its n inputs 4a-h with its single output A'. Accordingly the first selector valve unit 4 is configured such that it can selectively fluidly connect any one of the hollow needles 2a-h (which are fluidly connected to the respective n inputs 4a-h of the first selector valve 4) with the m flow cells 3a-d (whose inputs 3a'-3d' are fluidly connected to the single output 4' of the first selector valve unit 4). In this example the first selector valve unit 4 comprises a movable conduit 40; the movable conduit can be moved into eight different positions, in each of which is fluidly connects one said inputs 4a-h to the single output 4' (however it should be understood that the first selector valve unit 4 is not limited to having such a configuration).

[0019] Specifically in this embodiment the first selector valve unit 4 can be selectively configured into any one of n different configurations

(wherein n is the number of hollow needles 2a-h in the needle unit 2. As mentioned above n is equal to eight in this example): when the first selector valve unit 4 is in a first configuration the single output 4' is fluidly connected to the first input 4a only, thus fluidly connecting the first hollow needle 2a only with all of the m flow cells 3a-d; when the first selector valve unit 4 a second configuration the single output 4' is fluidly connected to the second input 4b only thus fluidly connecting the second hollow needle 2b only with all of the m flow cells 3a-d; when the first selector valve unit 4 a third configuration the single output 4' is fluidly connected to the third input 4c only thus fluidly connecting the third hollow needle 2c only with all of the m flow cells 3a-d; when the first selector valve unit 4 a fourth configuration the single output 4' is fluidly connected to the fourth input 4d only thus fluidly connecting the fourth hollow needle 2d only with all of the m flow cells 3a-d; when the first selector valve unit 4 a fifth configuration the single output 4' is fluidly connected to the fifth input 4e only thus fluidly connecting the fifth hollow needle 2e only with all of the m flow cells 3a-d; when the first selector valve unit 4 a sixth configuration the single output 4' is fluidly connected to the sixth input 4f only thus fluidly connecting the sixth hollow needle 2f only with all of the m flow cells 3a-d; when the first selector valve unit 4 a seventh configuration the single output 4' is fluidly connected to the seventh input 4g only thus fluidly connecting the seventh hollow needle 2g only with all of the m flow cells 3a-d; when the first selector valve unit 4 an eight configuration the single output 4' is fluidly connected to the eight input 4h only thus fluidly connecting the eight hollow needle 2h only with all of the m flow cells 3a- d.

[0020] In the preferred embodiment, the first selector valve unit 4 comprises a rotary valve. In order to move the first selector valve unit 4 into any one of its five different configurations, the the movable conduit 40 is positioned at one of five different positions using a motor to a position which allows a fluid passage from the respective input 4a'-h' (and thus from the respective hollow needle 2a-h) to the single output 4' (note in this embodiment the movable conduit 40 is provided on a rotor and the single output 4' is provided on a stator). [0021] In a further variation of this embodiment, the first selector valve unit 4 comprises 'n' 2/2 solenoid valves or pinch valves, i.e. the number of 2/2 solenoid valves or pinch valves correspond to the number of needles in the needle unit 2.

[0022] In this embodiment there is provided a single pumping means 12. The single pumping means 12 is configured so that it is selectively operable to provide negative pressure (e.g. negative fluid pressure) at its output 12e. Most preferably the single pumping means 12 is configured so that it is selectively operable to provide positive pressure (e.g. positive fluid pressure) or negative pressure (e.g. negative fluid pressure) at its output 12e. The single pumping means 12 may have any suitable configuration. In this example, the single pumping means 12 comprises a syringe 12a, a switching valve 12b, a buffer reservoir 12c which contains a buffer fluid, a waste reservoir 12d and an output 12e. Preferably, before operating the single pumping mean 12 to provide a positive pressure at its output 12e, the single pumping means 12 is first primed by configuring the switching valve 12b to fluidly connect the syringe 12a to the waste reservoir 12d, so as to allow buffer fluid to pass from the syringe 12a to the waste reservoir 12d; then the buffer fluid contents of the syringe 12a are dispensed into the waste reservoir 12d. Then the switching valve 12b is configured to fluidly connect the syringe 12a to the buffer reservoir 12c, so as to allow buffer fluid to pass from the buffer reservoir 12c to the syringe 12a. The syringe 12a is then filled with buffer fluid from the buffer reservoir 12c by aspirating buffer fluid from the buffer reservoir 12c. In order to provide positive pressure, the switching valve 12b is then configured to fluidly connect the syringe 12a to the output 12e; the buffer fluid contained in the syringe 12a is then dispensed from the syringe; the dispense buffer fluid creates the positive pressure at the output 12e. Similarly, preferably, before providing negative pressure at the output 12e, the syringe 12a is typically at least partially emptied (and most preferably is fully emptied); the switching valve 12b is configured to fluidly connect the syringe 12a to the waste reservoir 12d so as to allow fluid to pass from the syringe 12a to the waste reservoir 12d; the fluid contents of the syringe 12a is then at least partially emptied into the waste reservoir 12d. In order to provide negative pressure, the switching valve 12b is configured to fluidly connect the syringe 12a to the output 12e; fluid present in the output 12e is aspirated into the syringe 12a; aspirating fluid from the output 12e into the syringe 12a creates the negative pressure at the output 12e.

[0023] The second selector valve unit 6 is fluidly connected between respective m outputs 3a"-3d" of the m flow cells 3a-d in said flow cell unit 3 and said pumping means 12. Specifically the second selector valve unit 6 is connected between the output 12e of said pumping means 12 and the m outputs 3a"-3d" of the m flow cells 3a-d.

[0024] The second selector valve unit 6 is configured to selectively fluidly connect the pumping means 12 with one or more of said m flow cells 3a-d.

[0025] Specifically, the second selector valve unit 6 comprises m valves, each of the respective m valves is connected between a respective one of said m outputs 3a"-3d" of the m flow cells 3a-d and the output 12e of the pumping means 12.

[0026] Most preferably the number of valves provided in the second selector valve unit 6 corresponds to the number of flow cells 3a-d in the flow cell unit 3. In this example since m is equal to four, the second selector valve unit 6 comprises a first valve 6a which has an input 6a" and an output 6a'; a second valve 6b which has an input 6b" and an output 6b'; a third valve 6c which has an input 6c" and an output 6c'; and a fourth valve 6d which has an input 6d" and an output 6d'.

[0027] The input 6a" of the first valve 6a is fluidly connected to the output 12e of the pumping means 12, and the output 6a' of the first valve 6a is fluidly connected to the output 3a" of the first flow cell 3a. The input 6b" of the second valve 6b is fluidly connected to the output 12e of the pumping means 12, and the output 6b' of the second valve 6b is fluidly connected to the output 3b" of the second flow cell 3b. The input 6c" of the third valve 6c is fluidly connected to the output 12e of the pumping means 12, and the output 6c' of the third valve 6c is fluidly connected to the output 3c" of the third flow cell 3c. The input 6d" of the fourth valve 6d is fluidly connected to the output 12e of the pumping means 12, and the output 6d' of the fourth valve 17d is fluidly connected to the output 3d" of the fourth flow cell 3d.

[0028] Each of the first, second, third and fourth valves 6a-d of the second selector valve unit 6 can be selectively opened or closed.

Accordingly, when the first valve 6a is opened it will fluidly connect the pumping means 12 to the output 3a" of the first flow cell 3a; when the second valve 6b is opened it will fluidly connect the pumping means 12 to the output 3b" of the second flow cell; when the third valve 6c is opened it will fluidly connect the pumping means 12 to the output 3c" of the third flow cell 3c; when the fourth valve 6d is opened it will fluidly connect the pumping means 12 to the output 3d" of the fourth flow cell 3d.

[0029] The second selector valve unit 6 is selectively arrangeable in at least m+1 different configurations, wherein m is the number of flow cells 3a-d in the flow cell unit 3. Accordingly, in this embodiment the second selector valve unit 6 is selectively arrangeable in at least five different configurations:

[0030] When the second selector valve unit 6 is in a first configuration, the first valve 6a is opened and the second, third, fourth valves 6b-d are closed, thus fluid flowing out of the first selector valve unit 4 via single output 4' of the selector valve unit 4, will flow through the first flow cell 3a only. Also when the second selector valve unit 6 is in its first configuration the pumping means 12 will be fluidly connected to the output 3a" of the first flow cell 3a only.

[0031] When the second selector valve unit 6 is in a second

configuration, the second valve 6b is opened and the first, third, fourth valves 6a,c,d are closed, thus fluid flowing out of the first selector valve unit 4 via single output 4' of the selector valve unit 4, will flow through the second flow cell 3b only. Also when the second selector valve unit 6 is in its second configuration, the pumping means 12 will be fluidly connected to the output 3b" of the second flow cell 3b only.

[0032] When the second selector valve unit 6 is in a third configuration, the third valve 6c is opened and the first, second, and fourth valves 6a,b,d are closed, thus fluid flowing out of the first selector valve unit 4 via single output 4' of the selector valve unit 4, will flow through the third flow cell 3c only. Also when the second selector valve unit 6 is in its third

configuration the pumping means 12 will be fluidly connected to the output 3c" of the third flow cell 3c only.

[0033] When the second selector valve unit 6 is in a fourth

configuration, the fourth valve 6c is opened and the first, second, and third valves 6a,b,c are closed, thus fluid flowing out of the first selector valve unit 4 via single output 4' of the selector valve unit 4, will flow through the fourth flow cell 3d only. Also when the second selector valve unit 6 is in its fourth configuration, the pumping means 12 will be fluidly connected to the output 3d" of the fourth flow cell 3d only.

[0034] When the second selector valve unit 6 is in a fifth configuration, all of the first, second, third and fourth valves 6a-d are opened, thus fluid flowing out of the first selector valve unit 4 via single output 4' of the selector valve unit 4, will flow through all of the flow cells 3a-d in the flow cell unit 3. Also when the second selector valve unit 6 is in its fifth

configuration, the pumping means 12 will be simultaneously fluidly connected to all of the outputs 3a"-3d" of all of the flow cells 3a-d in the flow cell unit 3.

[0035] Optionally the second selector valve unit 6 could be selectively arrangeable in a sixth configuration wherein all of the first, second, third and fourth valves 6a-d are closed; thus fluid flowing out of the first selector valve unit 4 via single output 4' of the selector valve unit 4, will not flow through any of the flow cells 3a-d. [0036] It should be understood that each of said m valves 6a-d in the second selector valve unit 6 may take any suitable form. For example, most preferably each of said m valves 6a-d is a solenoid valve. In a further variation of this embodiment instead of a second selector valve unit 6 comprising m solenoid valves 6a-d, the second selector valve unit 6 may comprises a rotary valve which can be arranged in at least five

configurations: a first configuration wherein the second selector valve unit 6 fluidly connects the output 3a" of the first flow cell 3a only with the pumping means 12; a second configuration wherein the second selector valve unit 6 fluidly connects the output 3b" of the second flow cell 3b only with the pumping means 12; a third configuration wherein the second selector valve unit 6 fluidly connects the output 3c" of the third flow cell 3c only with the pumping means 12; a fourth configuration wherein the second selector valve unit 6 fluidly connects the output 3d" of the fourth flow cell 3a only with the pumping means 12; and a fifth configuration wherein the second selector valve unit 6 simultaneously fluidly connects all of the outputs 3a"-d" of all of the flow cells 3a-d in the flow cell unit 3 with the pumping means 12.

[0037] Advantageously the assembly 100 can be used to screen a plurality of different sample fluids consecutively, for predefined molecules (i.e. molecules which are known or suspected to bind to the ligands provided on the test surfaces of one or more of the flow cells 3a-d). During use different sample fluids which are to be screened may be provided in each respective reservoir 1' of the sample holder tray 1; in other words the sample fluids provided in said different reservoirs 1' may have different compositions (how this is not essential; it could be that some of the sample fluids in different reservoirs 1' have the same composition). In this example the different sample fluids having different compositions are provided in said respective reservoirs 1': In particular, in a first row of reservoirs, a first sample fluid is provided in a first reservoir 1 a' of that row; a second sample fluid is provided in a second reservoir 1 b' of said row; a third sample fluid is provided in a third reservoir 1c' of said row; a fourth sample fluid is provided in a fourth reservoir 1 d' of said row; a fifth sample fluid is provided in a fifth reservoir 1e' of said row; a sixth sample fluid is provided in a sixth reservoir 1f of said row; a seventh sample fluid is provided in a seventh reservoir 1 g' of said row; an eight sample fluid is provided in an eight reservoir 1 h' of said row.

[0038] The needle unit 2 is then arranged so that each of the respective n hollow needles 2a-h is simultaneously inserted into a respective reservoir 1 a-h of the sample tray holder 1 ; specifically the needle unit 2 is arranged so that, the first hollow needle 2a is inserted into said first reservoir 1 a', the second hollow needle 2b is inserted into said second reservoir 1 b', the third hollow needle 2c is inserted into said third reservoir 1 c', the fourth hollow needle 2d is inserted into said fourth reservoir 1 d', the fifth hollow needle 2e is inserted into said fifth reservoir 1 e', the sixth hollow needle 2f is inserted into said sixth reservoir 1f', the seventh hollow needle 2g is inserted into said seventh reservoir 1 g', the eight hollow needle 2h is inserted into said eight reservoir 1 h'. At least the tip of each hollow needle 2a-h is submerged in the respective sample fluids contained in the respective reservoirs 1 a'-h'. It should be noted that the moveable stage 2' may move the needle unit 2 into a position wherein each of the respective n hollow needles 2 are simultaneously inserted into a respective reservoir 1 a-h. [0039] The second selector valve unit 6 is arranged into its fifth configuration so that all of the first, second, third and fourth valves 6a-d are opened.

[0040] The first selector valve unit 4 is then arranged into its first configuration so that the single output 4' is fluidly connected to the first input 4a only, thus fluidly connecting the first hollow needle 2a only with all of the m flow cells 3a-d.

[0041] The flow cells 3a-d in the flow cell unit 3 are then contacted with the first sample fluid which is present in the first reservoir 1 a in an injection step. The pumping means 12 is then operated to provide a negative pressure at its output 12e. The negative pressure causes the first sample fluid which is present in the first reservoir 1 a, to be aspirated into the first hollow needle 2a, pass through the first hollow needle 2a into the first input 4a of the first selector valve unit 4, out of the first selector valve unit via the single output 4', and from the single output 4' into all of the flow cells 3a-d in the flow cell unit 3.

[0042] Accordingly the first sample fluid will contact the test surfaces of each of the first, second, third and fourth flow cells 3a-d; and more specifically will contact ligands which are present on said respective test surfaces. If the first sample fluid contains molecules which can bind to the ligands which are on the test surfaces of any the first, second, third and fourth flow cells 3a-d, these molecules will become bound to those ligands when the first sample fluid flows through that flow cell. As the first sample fluid flows through the first, second, third and fourth flow cells 3a-d, this sensor 103' is operated to detect if molecules of the first sample fluid have become bound to ligands on the test surfaces of any of the first, second, third or fourth flow cells 3a-d.

[0043] Optionally, the flow cells 3a-d in the flow cell unit 3 are then rinsed in a rinsing step. In order to carry out the rising step, the switching valve 12b is configured to fluidly connect the syringe 12a to the waste reservoir 12d, so as to allow buffer fluid to pass from the syringe 12a to the waste reservoir 12d; then the buffer fluid contents of the syringe 12a are dispensed into the waste reservoir 12d. Then the switching valve 12b is configured to fluidly connect the syringe 12a to the buffer reservoir 12c, so as to allow buffer fluid to pass from the buffer reservoir 12c to the syringe 12a. The syringe 12a is then filled with buffer fluid from the buffer reservoir 12c by aspirating buffer fluid from the buffer reservoir 12c. The pumping means 12 is then operated to provide a positive pressure at its output 12e. The positive pressure causes buffer fluid, which is present at the syringe 12a, to flow into the flow cells 3a-d in the flow cell unit 3, effectively displacing the first sample fluid and thus rinsing the flow cells 3a-d, and into the single output 4' of the first selector valve unit 4 and out of the first input 4a of the first selector valve unit 4 into the first hollow needle 2a and into the reservoir 1 a. [0044] Then, the first selector valve unit 4 is moved to its second position so that the single output 4' is fluidly connected to the second input 4b only, thus fluidly connecting the second hollow needle 2b only with all of the m flow cells 3a-d.

[0045] The pumping means 12 is then operated to provide a negative pressure at its output 12e. The negative pressure causes the second sample fluid which is present in the second reservoir 1 b, to be aspirated into the second hollow needle 22b, pass through the second hollow needle 2b into the second input 4b of the first selector valve unit 4, out of the first selector valve unit via the single output 4', and from the single output 4' into all of the flow cells 3a-d in the flow cell unit 3.

[0046] Accordingly, the second sample fluid will contact the test surfaces of each of the first, second, third and fourth flow cells 3a-d; and more specifically will contact ligands which are present on said respective test surfaces. If the second sample fluid contains molecules which can bind to the ligands which are on the test surfaces of any the first, second, third and fourth flow cells 3a-d, these molecules will become bound to those ligands when the second sample fluid flows through that flow cell. As the second sample fluid flows through the first, second, third and fourth flow cells 3a- d, the sensor 103' is operated to detect if molecules of the second sample fluid have become bound to ligands on the test surfaces of any of the first, second, third or fourth flow cells 3a-d.

[0047] Optionally, the flow cells 3a-d in the flow cell unit 3 are then rinsed by carrying out further rinsing step. Therefore the switching valve 12b is configured to fluidly connect the syringe 12a to the waste reservoir 12d, so as to allow buffer fluid to pass from the syringe 12a to the waste reservoir 12d; then the buffer fluid contents of the syringe 12a are dispensed into the waste reservoir 12d. Then the switching valve 12b is configured to fluidly connect the syringe 12a to the buffer reservoir 12c, so as to allow buffer fluid to pass from the buffer reservoir 12c to the syringe 12a. The syringe 12a is then filled with buffer fluid from the buffer reservoir 12c by aspirating buffer fluid from the buffer reservoir 12c. The pumping means 12 is then operated to provide a positive pressure at its output 12e. The positive pressure causes buffer fluid in the syringe 12a to flow into the flow cells 3a-d in the flow cell unit 3, effectively displacing the first sample fluid and thus rinsing the flow cells 3a-d, and into the single output 4' of the first selector valve unit 4 and out of the second input 4b of the first selector valve unit 4 into the second hollow needle 2b and into the second reservoir 1 b.

[0048] The first selector valve unit 4 is then arranged into its third configuration so that the single output 4' is fluidly connected to the third input 4c only, thus fluidly connecting the third hollow needle 2c only with all of the m flow cells 3a-d. The flow cells 3a-d in the flow cell unit 3 are then contacted with the third sample fluid which is present in the third reservoir 1c in an injection step: The pumping means 12 is operated to provide a negative pressure at its output 12e. The negative pressure causes the third sample fluid which is present in the third reservoir 1c, to be aspirated into the third hollow needle 2c, pass through the third hollow needle 2c into the third input 4c of the first selector valve unit 4, out of the first selector valve unit via the single output 4', and from the single output 4' into all of the flow cells 3a-d in the flow cell unit 3.

[0049] Accordingly, the third sample fluid, which was present in the third reservoir 1c, will contact the test surfaces of each of the first, second, third and fourth flow cells 3a-d; and more specifically will contact ligands which are present on said respective test surfaces. If the third sample fluid contains molecules which can bind to the ligands which are on the test surfaces of any the first, second, third and fourth flow cells 3a-d, these molecules will become bound to those ligands when the third sample fluid flows through that flow cell. As the third sample fluid flows through the first, second, third and fourth flow cells 3a-d, the sensor 103' is operated to detect if molecules of the second sample fluid have become bound to ligands on the test surfaces of any of the first, second, third or fourth flow cells 3a-d. [0050] Optionally, the flow cells 3a-d in the flow cell unit 3 are then rinsed by carrying out further rinsing step. Therefore the switching valve 12b is configured to fluidly connect the syringe 12a to the waste reservoir 12d, so as to allow buffer fluid to pass from the syringe 12a to the waste reservoir 12d; then the buffer fluid contents of the syringe 12a are dispensed into the waste reservoir 12d. Then the switching valve 12b is configured to fluidly connect the syringe 12a to the buffer reservoir 12c, so as to allow buffer fluid to pass from the buffer reservoir 12c to the syringe 12a. The syringe 12a is then filled with buffer fluid from the buffer reservoir 12c by aspirating buffer fluid from the buffer reservoir 12c. The pumping means 12 is then operated to provide a positive pressure at its output 12e. The positive pressure causes buffer fluid to flow into the flow cells 3a-d in the flow cell unit 3, effectively displacing the third sample fluid and thus rinsing the flow cells 3a-d, and into the single output 4' of the first selector valve unit 4 and out of the third input 4c of the first selector valve unit 4 into the third hollow needle 2c and into the third reservoir 1c.

[0051] The first selector valve unit 4 is then arranged into its fourth configuration so that the single output 4' is fluidly connected to the fourth input 4d only, thus fluidly connecting the fourth hollow needle 2d only with all of the m flow cells 3a-d.

[0052] The flow cells 3a-d in the flow cell unit 3 are then contacted with the fourth sample fluid which is present in the fourth reservoir 1 d in an injection step: The pumping means 12 is operated to provide a negative pressure at its output 12e. The negative pressure causes the fourth sample fluid which is present in the fourth reservoir 1d, to be aspirated into the fourth hollow needle 2d, pass through the fourth hollow needle 2d into the fourth input 4d of the first selector valve unit 4, out of the first selector valve unit via the single output 4', and from the single output 4' into all of the flow cells 3a-d in the flow cell unit 3.

[0053] Accordingly, the fourth sample fluid, which was present in the fourth reservoir 1 d, will contact the test surfaces of each of the first, second, third and fourth flow cells 3a-d; and more specifically will contact ligands which are present on said respective test surfaces. If the fourth sample fluid contains molecules which can bind to the ligands which are on the test surfaces of any the first, second, third and fourth flow cells 3a-d, these molecules will become bound to those ligands when the fourth sample fluid flows through that flow cell. As the fourth sample fluid flows through the first, second, third and fourth flow cells 3a-d, this sensor 103' is operated to detect if molecules of the fourth sample fluid have become bound to ligands on the test surfaces of any of the first, second, third or fourth flow cells 3a-d.

[0054] Optionally, the flow cells 3a-d in the flow cell unit 3 are then rinsed by carrying out further rinsing step. Therefore the switching valve 12b is configured to fluidly connect the syringe 12a to the waste reservoir 12d, so as to allow buffer fluid to pass from the syringe 12a to the waste reservoir 12d; then the buffer fluid contents of the syringe 12a are dispensed into the waste reservoir 12d. Then the switching valve 12b is configured to fluidly connect the syringe 12a to the buffer reservoir 12c, so as to allow buffer fluid to pass from the buffer reservoir 12c to the syringe 12a. The syringe 12a is then filled with buffer fluid from the buffer reservoir 12c by aspirating buffer fluid from the buffer reservoir 12c. The pumping means 12 is then operated to provide a positive pressure at its output 12e. The positive pressure causes buffer fluid to flow into the flow cells 3a-d in the flow cell unit 3, effectively displacing the fourth sample fluid and thus rinsing the flow cells 3a-d, and into the single output 4' of the first selector valve unit 4 and out of the fourth input 4d of the first selector valve unit 4 into the fourth hollow needle 2d and into the fourth reservoir 1 d.

[0055] The first selector valve unit 4 is then arranged into its fifth configuration so that the single output 4' is fluidly connected to the fifth input 4e only, thus fluidly connecting the fifth hollow needle 2e only with all of the m flow cells 3a-d.

[0056] The flow cells 3a-d in the flow cell unit 3 are then contacted with the fifth sample fluid which is present in the fifth reservoir 1 e in an injection step: The pumping means 12 is operated to provide a negative pressure at its output 12e. The negative pressure causes the fourth sample fluid which is present in the fifth reservoir 1e, to be aspirated into the fifth hollow needle 2e, pass through the fifth hollow needle 2e into the fifth input 4e of the first selector valve unit 4, out of the first selector valve unit via the single output 4', and from the single output 4' into all of the flow cells 3a-d in the flow cell unit 3.

[0057] Accordingly, the fifth sample fluid, which was present in the fifth reservoir 1e, will contact the test surfaces of each of the first, second, third and fourth flow cells 3a-d; and more specifically will contact ligands which are present on said respective test surfaces. If the fifth sample fluid contains molecules which can bind to the ligands which are on the test surfaces of any the first, second, third and fourth flow cells 3a-d, these molecules will become bound to those ligands when the fifth sample fluid flows through that flow cell. As the fifth sample fluid flows through the first, second, third and fourth flow cells 3a-d, this sensor 103' is operated to detect if molecules of the fifth sample fluid have become bound to ligands on the test surfaces of any of the first, second, third or fourth flow cells 3a-d.

[0058] Optionally, the flow cells 3a-d in the flow cell unit 3 are then rinsed by carrying out further rinsing step. Therefore the switching valve 12b is configured to fluidly connect the syringe 12a to the waste reservoir 12d, so as to allow buffer fluid to pass from the syringe 12a to the waste reservoir 12d; then the buffer fluid contents of the syringe 12a are dispensed into the waste reservoir 12d. Then the switching valve 12b is configured to fluidly connect the syringe 12a to the buffer reservoir 12c, so as to allow buffer fluid to pass from the buffer reservoir 12c to the syringe 12a. The syringe 12a is then filled with buffer fluid from the buffer reservoir 12c by aspirating buffer fluid from the buffer reservoir 12c. The pumping means 12 is then operated to provide a positive pressure at its output 12e. The positive pressure causes buffer fluid to flow into the flow cells 3a-d in the flow cell unit 3, effectively displacing the fifth sample fluid and thus rinsing the flow cells 3a-d, and into the single output 4' of the first selector valve unit 4 and out of the fifth input 4e of the first selector valve unit 4 into the fifth hollow needle 2e and into the fifth reservoir 1e.

[0059] The first selector valve unit 4 is then arranged into its sixth configuration so that the single output 4' is fluidly connected to the sixth input 4f only, thus fluidly connecting the sixth hollow needle 2f only with all of the m flow cells 3a-d.

[0060] The flow cells 3a-d in the flow cell unit 3 are then contacted with the sixth sample fluid which is present in the sixth reservoir 1f in an injection step: The pumping means 12 is operated to provide a negative pressure at its output 12f. The negative pressure causes the fourth sample fluid which is present in the sixth reservoir 1f, to be aspirated into the sixth hollow needle 2f, pass through the sixth hollow needle 2f into the sixth input 4f of the first selector valve unit 4, out of the first selector valve unit via the single output 4', and from the single output 4' into all of the flow cells 3a-d in the flow cell unit 3.

[0061] Accordingly, the sixth sample fluid, which was present in the sixth reservoir 1f, will contact the test surfaces of each of the first, second, third and fourth flow cells 3a-d; and more specifically will contact ligands which are present on said respective test surfaces. If the sixth sample fluid contains molecules which can bind to the ligands which are on the test surfaces of any the first, second, third and fourth flow cells 3a-d, these molecules will become bound to those ligands when the sixth sample fluid flows through that flow cell. As the sixth sample fluid flows through the first, second, third and fourth flow cells 3a-d, this sensor 103' is operated to detect if molecules of the sixth sample fluid have become bound to ligands on the test surfaces of any of the first, second, third or fourth flow cells 3a- d.

[0062] Optionally, the flow cells 3a-d in the flow cell unit 3 are then rinsed by carrying out further rinsing step. Therefore, the switching valve 12b is configured to fluidly connect the syringe 12a to the waste reservoir 12d, so as to allow buffer fluid to pass from the syringe 12a to the waste reservoir 12d; then the buffer fluid contents of the syringe 12a are dispensed into the waste reservoir 12d. Then the switching valve 12b is configured to fluidly connect the syringe 12a to the buffer reservoir 12c, so as to allow buffer fluid to pass from the buffer reservoir 12c to the syringe 12a. The syringe 12a is then filled with buffer fluid from the buffer reservoir 12c by aspirating buffer fluid from the buffer reservoir 12c. The pumping means 12 is then operated to provide a positive pressure at its output 12f. The positive pressure causes buffer fluid to flow into the flow cells 3a-d in the flow cell unit 3, effectively displacing the sixth sample fluid and thus rinsing the flow cells 3a-d, and into the single output 4' of the first selector valve unit 4 and out of the sixth input 4f of the first selector valve unit 4 into the sixth hollow needle 2f and into the sixth reservoir 1f.

[0063] The first selector valve unit 4 is then arranged into its seventh configuration so that the single output 4' is fluidly connected to the seventh input 4g only, thus fluidly connecting the seventh hollow needle 2g only with all of the m flow cells 3a-d.

[0064] The flow cells 3a-d in the flow cell unit 3 are then contacted with the seventh sample fluid which is present in the seventh reservoir 1g in an injection step: The pumping means 12 is operated to provide a negative pressure at its output 12g. The negative pressure causes the fourth sample fluid which is present in the seventh reservoir 1 g, to be aspirated into the seventh hollow needle 2g, pass through the seventh hollow needle 2g into the seventh input 4g of the first selector valve unit 4, out of the first selector valve unit via the single output 4', and from the single output 4' into all of the flow cells 3a-d in the flow cell unit 3.

[0065] Accordingly, the seventh sample fluid, which was present in the seventh reservoir 1 g, will contact the test surfaces of each of the first, second, third and fourth flow cells 3a-d; and more specifically will contact ligands which are present on said respective test surfaces. If the seventh sample fluid contains molecules which can bind to the ligands which are on the test surfaces of any the first, second, third and fourth flow cells 3a-d, these molecules will become bound to those ligands when the seventh sample fluid flows through that flow cell. As the seventh sample fluid flows through the first, second, third and fourth flow cells 3a-d, this sensor 103' is operated to detect if molecules of the seventh sample fluid have become bound to ligands on the test surfaces of any of the first, second, third or fourth flow cells 3a-d.

[0066] Optionally, the flow cells 3a-d in the flow cell unit 3 are then rinsed by carrying out further rinsing step. Therefore, the switching valve 12b is configured to fluidly connect the syringe 12a to the waste reservoir 12d, so as to allow buffer fluid to pass from the syringe 12a to the waste reservoir 12d; then the buffer fluid contents of the syringe 12a are dispensed into the waste reservoir 12d. Then the switching valve 12b is configured to fluidly connect the syringe 12a to the buffer reservoir 12c, so as to allow buffer fluid to pass from the buffer reservoir 12c to the syringe 12a. The syringe 12a is then filled with buffer fluid from the buffer reservoir 12c by aspirating buffer fluid from the buffer reservoir 12c. The pumping means 12 is then operated to provide a positive pressure at its output 12g. The positive pressure causes buffer fluid to flow into the flow cells 3a-d in the flow cell unit 3, effectively displacing the seventh sample fluid and thus rinsing the flow cells 3a-d, and into the single output 4' of the first selector valve unit 4 and out of the seventh input 4g of the first selector valve unit 4 into the seventh hollow needle 2g and into the seventh reservoir 1 g.

[0067] The first selector valve unit 4 is then arranged into its eight configuration so that the single output 4' is fluidly connected to the eight input 4h only, thus fluidly connecting the eight hollow needle 2h only with all of the m flow cells 3a-d.

[0068] The flow cells 3a-d in the flow cell unit 3 are then contacted with the eighth sample fluid which is present in the eight reservoir 1 h in an injection step: The pumping means 12 is operated to provide a negative pressure at its output 12h. The negative pressure causes the fourth sample fluid which is present in the eighth reservoir 1 h, to be aspirated into the eighth hollow needle 2h, pass through the eighth hollow needle 2h into the eighth input 4h of the first selector valve unit 4, out of the first selector valve unit via the single output 4', and from the single output 4' into all of the flow cells 3a-d in the flow cell unit 3.

[0069] Accordingly, the eight sample fluid, which was present in the eight reservoir 1 h, will contact the test surfaces of each of the first, second, third and fourth flow cells 3a-d; and more specifically will contact ligands which are present on said respective test surfaces. If the eighth sample fluid contains molecules which can bind to the ligands which are on the test surfaces of any the first, second, third and fourth flow cells 3a-d, these molecules will become bound to those ligands when the eighth sample fluid flows through that flow cell. As the eighth sample fluid flows through the first, second, third and fourth flow cells 3a-d, this sensor 103' is operated to detect if molecules of the eighth sample fluid have become bound to ligands on the test surfaces of any of the first, second, third or fourth flow cells 3a-d.

[0070] Optionally, the flow cells 3a-d in the flow cell unit 3 are then rinsed by carrying out further rinsing step. Therefore, the switching valve 12b is configured to fluidly connect the syringe 12a to the waste reservoir 12d, so as to allow buffer fluid to pass from the syringe 12a to the waste reservoir 12d; then the buffer fluid contents of the syringe 12a are dispensed into the waste reservoir 12d. Then the switching valve 12b is configured to fluidly connect the syringe 12a to the buffer reservoir 12c, so as to allow buffer fluid to pass from the buffer reservoir 12c to the syringe 12a. The syringe 12a is then filled with buffer fluid from the buffer reservoir 12c by aspirating buffer fluid from the buffer reservoir 12c. The pumping means 12 is then operated to provide a positive pressure at its output 12h. The positive pressure causes buffer fluid to flow into the flow cells 3a-d in the flow cell unit 3, effectively displacing the eighth sample fluid and thus rinsing the flow cells 3a-d, and into the single output 4' of the first selector valve unit 4 and out of the eighth input 4h of the first selector valve unit 4 into the eighth hollow needle 2h and into the eight reservoir 1 h. [0071] Advantageously, in the respective rinsing step mentioned above, the first, second, third, fourth, fifth, sixth, seventh and eight sample fluids displaced by the buffer fluid are collected in the respective reservoirs 1 a-h and can be reused for further analysis. In a preferred embodiment, the volume of the buffer fluid which is dispensed from the pumping means 12 into the flow cells 3a-d in the flow cell unit 3 during the rising step, is equal to or larger than the volume of each respective sample fluid which flowed into the flow cells 3a-d in the flow cell unit 3 during the respective injection step. Preferably, the volume of the buffer fluid which is dispensed from the pumping means 12 into the flow cells 3a-d in the flow cell unit 3 during the rising step, is larger than twice the injection volume of sample fluid, or larger than three times the volume of sample fluid which flowed into the flow cells 3a-d in the flow cell unit 3 during the respective injection step.

[0072] Then, the needle unit 2 is washed to avoid contamination of next samples. The needle unit is then moved to the next row of reservoirs in the sample holder tray 1, and is arranged so that each of the respective n hollow needles 2a-h is simultaneously inserted into a respective reservoir 1 a-h belonging to said next row of the sample tray holder 1 ; and the above-mentioned steps are repeated for each of the sample fluids contained in the reservoirs in said next row. These steps are preferably repeated until all of the sample fluids contained in reservoirs of the sample tray holder 1 have been screened. Advantageously, in the present invention the sample fluids contained in the reservoirs of the sample tray holder, can be made to contact the same test surface (i.e. the test surface of the same flow cell) in rapid succession.

[0073] As mentioned above, the sensor 103' is operated to detect if molecules of a sample fluid have become bound to ligands on the test surfaces of any of the first, second, third or fourth flow cells 3a-d.

Preferably the sensor signal is recorded to monitor binding of sample molecules to the sensor surface, and binding is detected by for instance evaluating the difference of the signals obtained in the first flow cell 3a or second flow cell 3b or third flow cell 3c, to the signals obtained on the reference flow cell 3d which has no ligand immobilized. For example, one way to detect using the sensor 103' if molecules of a particular sample fluid have become bound to ligands on the test surface of any of a flow cell 3a-d is to compare an output signal of the sensor 103 to a reference output signal which is a signal which the sensor 103' outputs when said sample fluid flows through said flow cell when no ligands are provided on its test surface. Thus, the method may further comprise the steps of, for each of the respective m (eight) sample fluids: passing that sample fluid through a flow cell which is without ligands on its test surface; obtaining an output signal from the sensor 103' as the sample fluid passes through said flow cell which is without ligands on its test surface, wherein this output signal defines a reference signal. Then any of the above-mentioned steps of operating the sensor 103' to detect if molecules of a sample fluid have become bound to ligands on the test surfaces of any of the first, second, third or fourth flow cells 3a-d, may comprise, obtaining an output signal from the sensor as the sample fluid passes through the first, second, third or fourth flow cells 3a-d (one or more of which have ligands on its test surface); and comparing said output signal with said reference signal. It is then determined that a molecule of said sample fluid has bound to the ligands of a flow cell if the output signal differs from the reference signal.

[0074] Optionally, prior to performing the method of screening sample fluids for predefined molecules, described above, a step of providing ligands on the respective test surfaces of one or more of said m flow cells 3a-h in said flow cell unit 3 may be performed.

[0075] It should be noted that in one embodiment, prior to providing ligands on the respective test surfaces of one or more of said m flow cells 3a-h in said flow cell unit 3, a step of obtaining a reference signal from the sensor 103' for a sample fluid may be performed (and this step may be performed for a plurality of different sample fluid so that a reference signal from the sensor 103' is obtained for each different sample fluid). In order to obtain a reference signal for a sample fluid, the sample fluid is passed through a flow cell 3a-d when the flow cell 3a-d is without ligands on its test surface; obtaining an output signal from the sensor 103' as the sample fluid passes through said flow cell 3a-d, wherein this output signal defines said reference signal. It should be understood that the same steps as described above to pass a sample fluid though the flow cells for screening, could be performed in order to pass the sample fluid through the flow cell 3a-d (before that flow cell is provided with ligands on its test surface) in order to obtain said reference signal from the sensor 103' for that sample fluid.

[0076] Most preferably such a further step of providing ligands on the respective test surfaces of one or more of said m flow cells 3a-h in said flow cell unit 3 would be performed prior to using the assembly 101 to screen one or more sample fluids for predefined molecules. Most preferably the step of providing ligands on the respective test surfaces of one or more of said m flow cells 3a-h in said flow cell unit 3 comprises providing ligands on the test surfaces of a plurality (at least two) said flow cells 3a-h in said flow cell unit 3, wherein the type of ligands provided on the test surfaces differ between flow cells such that the test surfaces of said plurality of flow cells have different types of ligands.

[0077] In the following there will be described the steps carried out: ligands of a first type, which can bind to a first type of molecule, are provided on the test surface of the first flow cell 3a; ligands of a second type, which can bind to a second type of molecule, are provided on the test surface of the second flow cell 3b; ligands of a third type, which can bind to a third type of molecule, are provided on the test surface of the third flow cell 3c; ligands of a fourth type, which can bind to a fourth type of molecule, are provided on the test surface of the fourth flow cell 3d (it is understood that the number of ligands can be less than four, in which case at least one flow cell will be without any ligand provided thereon, and such flow cell without any ligand provided thereon can be used for referencing purposes):

[0078] A first immobilization reagent is provided in a first reservoir 1 a of a row in said sample try holder 1. It should be understood that the first immobilization reagent may comprise any suitable immobilization reagent; for example the first immobilization reagent may comprise a mixture of 1- Ethyl-3-(3-dimethylaminopropyl)carbodiimide(EDC) and N- hydroxysuccinimide (NHS) and/or Ethanolamine for amine coupling, and/or NiCl2 for His-Tag coupling, and/or any other suitable reagents. In this example the first immobilization reagent comprises a 1 :1 mixture of

EDC/NHS. It should be noted that an immobilization reagent and a substance which, when passed over the test surface of a flow cell, sticks to the test surface; the immobilization reagent can hold ligands (which are subsequently passed into the flow cell) so that the ligands are indirectly held on the test surface of the flow cell via the immobilization reagent.

[0079] r different types of ligands are provided in respective r different reservoirs 1 a-h of said row of said sample tray holder 1, wherein r is greater than one. As mentioned in this example four different types of ligands will be provided on the respective test surfaces of the respective flow cells 3a-d accordingly in this example r is four. It should be understood that r may have any value greater than one. Preferably r (then number of different types of ligands) is equal to m (the number of flow cells 3a-d in the flow cell unit 3. In this example r is equal to m so four different types of ligands are provided in the respective second, third, fourth and fifth reservoirs 1 b'- f of said row (i.e. the same row to which said first reservoir 1a' belongs) of said sample tray holder 1 :

[0080] Ligands of a first type (referred to hereafter as first ligands) are provided in the second reservoir 1 b of said row. In this example said first ligands, optionally diluted in acetate buffer, are provided in the second reservoir 1 b.

[0081] Ligands of a second type (referred to hereafter as second ligands) are provided in the third reservoir 1c. In this example said second ligands, optionally diluted in acetate buffer, are provided in the second reservoir 1c.

[0082] Ligands of a third type (referred to hereafter as third ligands) are provided in the fourth reservoir 1 d'. In this example said third ligands, optionally diluted in acetate buffer, is provided in the fourth reservoir 1d'. [0083] Ligands of a fourth type (referred to hereafter as fourth ligands) are provided in the fifth reservoir 1 e. In this example said fourth ligands, optionally diluted in acetate buffer, are provided in the fifth reservoir 1 e.

[0084] A second immobilization reagent is provided in at least one of the remaining reservoirs 1 f-h in said row. In this example the second immobilization reagent comprises Ethanolamine, however it will be understood that the second immobilization reagent may take any suitable form. In this example the second immobilization reagent is provided in the sixth reservoir 1f of said row.

[0085] Optionally a buffer is provided in the seventh and eight reservoirs 1 g, 1 h of said row.

[0086] The needle unit 2 is then arranged so that each of the respective n hollow needles 2a-h is simultaneously inserted into a respective reservoir 1 a-h; at least the tip of each hollow needle 2a-h is simultaneously submerged in the respective sample fluid contained in the respective reservoir 1 a-h into which it is inserted.

[0087] The second selector valve unit 6 is arranged into its fifth configuration so that all of the first, second, third and fourth valves 6a-d are opened. Also when the second selector valve unit 6 is in its fifth configuration, the pumping means 12 will be simultaneously fluidly connected to all of the outputs 3a"-3d" of all of the flow cells 3a-d in the flow cell unit 3.

[0088] The first selector valve unit 4 is then arranged into its first configuration so that the single output 4' is fluidly connected to the first input 4a only, thus fluidly connecting the first hollow needle 2a only with all of the m flow cells 3a-d.

[0089] The pumping means 12 is then operated to provide a negative pressure at its output 12e. The negative pressure causes the first

immobilization reagent which is present in the first reservoir 1 a, to be aspirated into the first hollow needle 2a, pass through the first hollow needle 2a into the first input 4a of the first selector valve unit 4, out of the first selector valve unit 4 via the single output 4', and from the single output 4' into all of the flow cells 3a-d in the flow cell unit 3.

[0090] Accordingly the first immobilization reagent will contact the test surfaces of each of the first, second, third and fourth flow cells 3a-d. When the first immobilization reagent flows through the first, second, third and fourth flow cells 3a-d, the first immobilization reagent will contact the test surfaces of each flow cell 3a-d, thereby activating the respective test surfaces. Activation of a test surface of a flow cell means providing an immobilization reagent (i.e. an reagent which can hold a ligand) on the test surface of the flow cell. An immobilization reagent may include reactive groups by carboxyl activation for example. Importantly, once a test surface of a flow cell has been activated by the first immobilization reagent, ligands which subsequently contact that test surface (e.g. ligands which flow over that test surface) will become attached to said test surface. The ligands which have become attached to the test surface, can in turn bind to predefined molecules in sample fluids which flow through said flow cell (the sensor 103' can be used to detect if predefined molecules in a sample fluid have bound to the ligands on the test surface of a flow cell).

[0091] The second selector valve unit 6 is arranged into its first

configuration so that the first valve 6a is opened and the second, third, fourth valves 6b-d are closed. Also, when the second selector valve unit 6 is in its first configuration the pumping means 12 will be fluidly connected to the output 3a" of the first flow cell 3a only.

[0092] The first selector valve unit 4 is then arranged into its second configuration so that the single output 4' is fluidly connected to the second input 4b only, thus fluidly connecting the second hollow needle 2b only with all of the first flow cell 3a only.

[0093] The pumping means 12 is then operated to provide a negative pressure at its output 12e. The negative pressure causes the first ligands which are present in the second reservoir 1 b, to be aspirated into the second hollow needle 2b, pass through the second hollow needle 2b into the second input 4b of the first selector valve unit 4, out of the first selector valve unit 4 via the single output 4', and from the single output 4' into the first flow cell 3a only.

[0094] As the first ligands flow through the first flow cell 3a they will become attached to the test surface of the first flow cell 3a (the first immobilization reagent which flowed over the test surface of the first flow cell 3a in the preceding step primed the test surface of the first flow cell 3a so that the first ligands will attach the first immobilization reagent which is present on the test surface of the first flow cell 3a when the first ligands flow over the test surface of the first flow cell 3a; in other words the first ligands will be indirectly attached to the test surface of the first flow cell 3a via the first immobilization reagent which is present on the test surface of the first flow cell 3). Accordingly the test surface of the first flow cell 3a is thus provided with the first ligands which can bind to a predefined molecule.

[0095] Optionally, the sensor 103' is used to monitor the amount of first ligands which attach to the test surface of the first flow cell 3a. This can be done by recording the signal output by the sensor 103' as the first ligands flow through the first flow cell 3a.

[0096] The second selector valve unit 6 is arranged into its second configuration so that the second valve 6b is opened and the first, third, fourth valves 6a,c,d are closed. Also when the second selector valve unit 6 is in its second configuration, the pumping means 12 will be fluidly connected to the output 3b" of the second flow cell 3b only.

[0097] The first selector valve unit 4 is then arranged into its third configuration so that the single output 4' is fluidly connected to the third input 4c only, thus fluidly connecting the third hollow needle 2c only with the second flow cell 3b only. [0098] The pumping means 12 is then operated to provide a negative pressure at its output 12e. The negative pressure causes the second ligands which are present in the third reservoir 1c, to be aspirated into the third hollow needle 2c, pass through the third hollow needle 2c into the third input 4c of the first selector valve unit 4, out of the first selector valve unit 4 via the single output 4', and from the single output 4' into the second flow cell 3b only.

[0099] As the second ligands flow through the second flow cell 3b they will become attached to the test surface of the second flow cell 3b (the first immobilization reagent which flowed over the test surface of the second flow cell 3b in the preceding step primed the test surface of the second flow cell 3b so that the second ligands will attach to the second

immobilization reagent which is present on the test surface of the second flow cell 3b when the second ligands flow over the test surface of the second flow cell 3b; in other words the second ligands will be indirectly attached to the test surface of the second flow cell 3b via the second immobilization reagent which is present on the test surface of the second flow cell 3b). Accordingly the test surface of the second flow cell 3b is thus provided with the second ligands which can bind to a predefined molecule.

[00100] Optionally, the sensor 103' is used to monitor the amount of second ligands which attach to the test surface of the second flow cell 3b. This can be done by recording the signal output by the sensor 103' as the second ligands flow through the second flow cell 3b.

[00101] The second selector valve unit 6 is arranged into its third configuration so that the third valve 6c is opened and the first, second, and fourth valves 6a,b,d are closed. Also when the second selector valve unit 6 is in its third configuration the pumping means 12 will be fluidly connected to the output 3c" of the third flow cell 3c only.

[00102] The first selector valve unit 4 is then arranged into its fourth configuration so that the single output 4' is fluidly connected to the fourth input 4d only, thus fluidly connecting the fourth hollow needle 2d only with the third flow cell 3c only.

[00103] The pumping means 12 is then operated to provide a negative pressure at its output 12e. The negative pressure causes the third ligands which are present in the fourth reservoir 1 d, to be aspirated into the fourth hollow needle 2d, pass through the fourth hollow needle 2d into the fourth input 4d of the first selector valve unit 4, out of the first selector valve unit 4 via the single output 4', and from the single output 4' into the third flow cell 3c only.

[00104] As the third ligands flow through the third flow cell 3c they will become attached to the test surface of the third flow cell 3c (the first immobilization reagent which flowed over the test surface of the third flow cell 3c in the preceding step primed the test surface of the third flow cell 3c so that the third ligands will attach to the third immobilization reagent which is present on the test surface of the third flow cell 3c when the third ligands flow over the test surface of the third flow cell 3c; in other words the third ligands will be indirectly attached to the test surface of the third flow cell 3c via the third immobilization reagent which is present on the test surface of the third flow cell 3c). Accordingly the test surface of the third flow cell 3c is thus provided with the third ligands which can bind to a predefined molecule.

[00105] Optionally, the sensor 103' is used to monitor the amount of third ligands which attach to the test surface of the third flow cell 3c. This can be done by recording the signal output by the sensor 103' as the third ligands flow through the third flow cell 3c.

[00106] The second selector valve unit 6 is arranged into its fourth configuration so that the fourth valve 6d is opened and the first, second, and third valves 6a,b,c are closed. Also when the second selector valve unit 6 is in its fourth configuration, the pumping means 12 will be fluidly connected to the output 3d" of the fourth flow cell 3d only. [00107] The first selector valve unit 4 is then arranged into its fifth configuration so that the single output 4' is fluidly connected to the fifth input 4e only, thus fluidly connecting the fifth hollow needle 2e only with the fourth flow cell 3d only.

[00108] The pumping means 12 is then operated to provide a negative pressure at its output 12e. The negative pressure causes the fourth ligands which are present in the fifth reservoir 1e, to be aspirated into the fifth hollow needle 2e, pass through the fifth hollow needle 2e into the fifth input 4e of the first selector valve unit 4, out of the first selector valve unit 4 via the single output 4', and from the single output 4' into the fourth flow cell 3d only.

[00109] As the fourth ligands flow through the fourth flow cell 3d they will become attached to the test surface of the fourth flow cell 3d (the first immobilization reagent which flowed over the test surface of the fourth flow cell 3d in the preceding step primed the test surface of the fourth flow cell 3d so that the fourth ligands will attach to the fourth immobilization reagent which is present on test surface of the fourth flow cell 3d when the fourth ligands flow over the test surface of the fourth flow cell 3d; in other words the fourth ligands will be indirectly attached to the test surface of the fourth flow cell 3d via the fourth immobilization reagent which is present on the test surface of the fourth flow cell 3d). Accordingly the test surface of the fourth flow cell 3d is thus provided with the fourth ligands which can bind to a predefined molecule.

[00110] Optionally, the sensor 103' is used to monitor the amount of fourth ligands which attach to the test surface of the fourth flow cell 3d. This can be done by recording the signal output by the sensor 103' as the fourth ligands flow through aarther embodiment of the present invention. The assembly 104 has many of the same features as the assembly 100 shown in Figure 1 and like features are awarded the same reference numbers. [00111] The assembly 104 comprises a plurality of pumping means 13a-h. The number of pumping means 13a-h corresponds to the number of hollow needles 2a-h in the needle unit 2, thus there are n pumping means 13a-h. Each respective pumping means 13a-h is fluidly connected to a respective hollow needle 2a-h of the needle unit 2. Each of the pumping means 13a-h can be operated to provide positive or negative pressure to a respective hollow needle 2a-h; each of the pumping means 13a-h preferably contain a buffer liquid reservoir. In this example each pumping means 13a-h is defined by a respective syringe pump 13a-h having a syringe; the syringe of each syringe pump 13a-h contains buffer liquid (preferably each syringe is filled with buffer liquid). The plurality of pumping means 13a-h and needle unit 2, together define a carrier module 102.

[00112] It is understood that although in this example the assembly 104 comprises a plurality of pumping means 13a-h, the assembly 104 may comprise an alternative configuration instead of the plurality of pumping means 13a-h; for example instead of the plurality of pumping means 13a-h the assembly 104 may comprise a single pumping module which comprises a single syringe pump and n switching valves, where the single syringe pump is fluidly connected to the inlet ports of each of the n switching valves in parallel, and each of the outputs of the n switching valves is fluidly connected to one respective hollow needle 2a-h, thus allowing to provide positive or negative pressure to the hollow needle 2a-h individually or collectively by controlling the corresponding switching valves and the syringe pump.

[00113] Notably the assembly 104 does not comprise a first selector valve 4. However, the assembly 104 does comprise a plurality of sockets 105a-h which are each fluidly connected to the inputs 3a"-d" of all of the flow cells 3a-d in the flow cell unit 3. The number of sockets 105a-h corresponds to the number of hollow needles 2a-h in the needle unit 2, thus there are n sockets 105a-h. Each socket 105a-h is suitable for cooperating with a respective hollow needle 2a-h in the needle unit 2; specifically, each socket 105a-h is suitable for receiving the tip of a respective needle 2a-h in the needle unit 2. Each socket 105a-h typically comprises an elastomeric membrane or septum; the elastomeric membrane or septum is configured so that when the respective socket 105a-h is moved to abut a respective hollow needle 2a-h the elastomeric membrane or septum forms a sealed interface with the hollow needle 2a-h; the elastomeric membrane or septum thus allows the socket 15a-h to be selectively fluidly connected to the hollow needles 2a-h.

[00114] The carrier module 102 is movable from a first position wherein the respective hollow needles 2a-h in the needle unit 2 are inserted into respective reservoirs 1 a-h in the sample tray holder 1 (when the carrier module is at the first position the pumping means 13a-h can be operated to provide a negative pressure which causes fluid in the respective reservoirs 1 a-h to be aspirated into the respective hollow needles 2a-h), to a second position where the respective hollow needles 2a-h are inserted into respective sockets 105a-h (when the carrier module is at the second position each of the pumping means 13a-h can be consecutively operated to provide a positive pressure which causes fluid in the respective hollow needles 2a-h to be expelled into the respective sockets 105a-h, and from the respective sockets 105a-h into said flow cells 3a-d). Any suitable means may be used to move the carrier module 102, for example a robotic arm or an xy table could be used. In this example the carrier module 102 is mounted on an xy table 2', which is operable to move the carrier module 102 between said first and second positions.

[00115] The assembly 104 can be used to screen a plurality of different sample fluids consecutively, for predefined molecules (i.e. molecules which are known to bind to the ligands provided on the test surfaces of one or more of the flow cells 3a-d). During use different sample fluids which are to be screened may be provided in each respective reservoir 1' of the sample holder tray 1; in other words the sample fluids provided in said different reservoirs 1' may have different compositions (how this is not essential; it could be that some of the sample fluids in different reservoirs 1' have the same composition). In this example the different sample fluids having different compositions are provided in said respective reservoirs 1': In particular, in a first row of reservoirs, a first sample fluid is provided in a first reservoir 1 a' of that row; a second sample fluid is provided in a second reservoir 1 b' of said row; a third sample fluid is provided in a third reservoir 1c' of said row; a fourth sample fluid is provided in a fourth reservoir 1d' of said row; a fifth sample fluid is provided in a fifth reservoir 1e' of said row; a sixth sample fluid is provided in a sixth reservoir 1f of said row; a seventh sample fluid is provided in a seventh reservoir 1 g' of said row; an eight sample fluid is provided in an eight reservoir 1 h' of said row.

[00116] The carrier module 102 is moved to its first position. In other words the carrier module 102 then arranged so that each of the respective n hollow needles 2a-h is inserted into a respective reservoir 1 a-h of the sample tray holder 1 ; specifically the needle unit 2 is arranged so that, the first hollow needle 2a is inserted into said first reservoir 1a', the second hollow needle 2b is inserted into said second reservoir 1 b', the third hollow needle 2c is inserted into said third reservoir 1c', the fourth hollow needle 2d is inserted into said fourth reservoir 1 d', the fifth hollow needle 2e is inserted into said fifth reservoir 1e', the sixth hollow needle 2f is inserted into said sixth reservoir 1f', the seventh hollow needle 2g is inserted into said seventh reservoir 1 g', the eight hollow needle 2h is inserted into said eight reservoir 1 h'. At least the tip of each hollow needle 2a-h is

submerged in the respective sample fluids contained in the respective reservoirs 1 a'-h'. It should be noted that the moveable stage 2' may move the needle unit 2 into a position wherein each of the respective n hollow needles 2 are simultaneously inserted into a respective reservoir 1 a-h.

[00117] Each of the pumping means 13a-h is then operated to provide a negative pressure. Each of the pumping means 13a-h may be operated simultaneously, or, alternatively, each of the pumping means 13a-h may be operated consecutively. The negative pressure causes a volume of the respective sample fluids which are present in the reservoirs 1 a-h, to be each aspirated into the respective hollow needle 2a-h in the needle unit 2. Said volume of each of the respective sample fluids which are aspirated into each respective hollow needles 2a-h, is referred to hereafter as the pickup volume ; in other words said pickup volume is defined as the volume of sample fluid present in one of the hollow needles 2a-h. Most preferably the same volume of sample fluid is aspirated into the respective hollow needles 2a-h; in other words each of the respective hollow needles 2a-h will have equal, or substantially equal, pickup volume. Accordingly, after this step has been performed, the first, second, third, fourth, fifth, sixth, seventh, and eight sample fluids are contained in the respective first, second, third, fourth, fifth, sixth, seventh, and eight hollow needles 2a-h.

[00118] The carrier module 102 is then moved to its second position.

[00119] The second selector valve 6 is arranged into its fifth

configuration, so that all of the first, second, third and fourth valves 6a-d are opened.

[00120] Each of the pumping means 13a-h is then operated to

consecutively provide a positive pressure. The positive pressure causes the respective sample fluids which are present in the respective hollow needle 2a-h to consecutively flow through sockets 105a-h and all of the flow cells 3a-d in the flow cell unit.

[00121] Most preferably the assembly 104 comprises a processor 130 which operates the pumping means 13a-h; most preferably the processor 130 which operates the pumping means 13a-h is configured so that the time between operating one of the pumping means 13a-h to provide positive pressure and operating the next pumping means 13a-h to provide positive pressure is less than 10 seconds.

[00122] As was the case with in the assembly 100, as each respective sample fluid flows though the flow cells 3a-d, the sensor 103' will be used to detect if any molecules in of that sample fluid binds to ligands on the test surfaces of any of the flow cells 3a-d.

[00123] Optionally, the flow cells 3a-d in the flow cell unit 3 are then rinsed in a rinsing step. To carry out said rinsing step the processor 130 which operates the plurality of pumping means 13a-h, so that each of the pump syringes 13a-h respectively aspirate a volume of buffer fluid which is greater than the pickup volume; the aspirated buffer fluid flows through each respective hollow needle 2a-h and through sockets 105a-h and all of the flow cells 3a-d in the flow cell unit, thereby effectively rinsing all of the flow cells 3a-d in the flow cell unit. It is understood that such a rinsing step can be executed between each injection of sample fluids into the flow cell unit.

[00124] Preferably the needle unit 2 is washed to avoid contamination of next samples.

[00125] The carrier module 102 is moved into its first position so that respective needles 2a-h are inserted into respective reservoirs 1 a-h belonging to said next row in the sample tray holder 1 ; and the above mentioned steps are repeated for each of the sample fluids contained in the reservoirs in said next row. These steps are preferably repeated until all of the sample fluids contained in reservoirs of the sample tray holder 1 have been screened. Advantageously, in the present invention the sample fluids contained in the reservoirs of the sample tray holder, can be made to contact the same test surface (i.e. the test surface of the same flow cell) in rapid succession.

[00126] Optionally, prior to performing any of the method of screening sample fluids for predefined molecules, described above, a step of providing ligands on the respective test surfaces of one or more of said m flow cells 3a-h in said flow cell unit 3 may be performed: ligands of a first type, which can bind to a first type of molecule, are provided on the test surface of the first flow cell 3a; ligands of a second type, which can bind to a second type of molecule, are provided on the test surface of the second flow cell 3b; ligands of a third type, which can bind to a third type of molecule, are provided on the test surface of the third flow cell 3c; ligands of a fourth type, which can bind to a fourth type of molecule, are provided on the test surface of the fourth flow cell 3d (it is understood that the number of ligands can be less than four, in which case at least one flow cell will be without any ligand provided thereon, and such flow cell without any ligand provided thereon can be used for referencing purposes): [00127] A first immobilization reagent is provided in a first reservoir 1 a of a row in said sample try holder 1. It should be understood that the first immobilization reagent may comprise any suitable immobilization reagent; for example the first immobilization reagent may comprise a mixture of 1- Ethyl-3-(3-dimethylaminopropyl)carbodiimide(EDC) and N- hydroxysuccinimide (NHS) and/or Ethanolamine for amine coupling, and/or NiCl2 for His-Tag coupling, and/or any other suitable reagents. In this example the first immobilization reagent comprises a 1 :1 mixture of

EDC/NHS. It should be noted that an immobilization reagent and a substance which, when passed over the test surface of a flow cell, sticks to the test surface; the immobilization reagent can hold ligands (which are subsequently passed into the flow cell) so that the ligands are indirectly held on the test surface of the flow cell via the immobilization reagent.

[00128] r different types of ligands are provided in respective r different reservoirs 1 a-h of said row of said sample tray holder 1, wherein r is greater than one. As mentioned in this example four different types of ligands will be provided on the respective test surfaces of the respective flow cells 3a-d accordingly in this example r is four. It should be understood that r may have any value greater than one. Preferably r (then number of different types of ligands) is equal to m (the number of flow cells 3a-d in the flow cell unit 3. In this example r is equal to m so four different types of ligands are provided in the respective second, third, fourth and fifth reservoirs 1 b'- f of said row (i.e. the same row to which said first reservoir 1 a' belongs) of said sample tray holder 1 :

[00129] Ligands of a first type (referred to hereafter as first ligands) are provided in the second reservoir 1 b of said row. In this example said first ligands, optionally diluted in acetate buffer, are provided in the second reservoir 1 b.

[00130] Ligands of a second type (referred to hereafter as second ligands) are provided in the third reservoir 1c. In this example said second ligands, optionally diluted in acetate buffer, are provided in the second reservoir 1c. [00131] Ligands of a third type (referred to hereafter as third ligands) are provided in the fourth reservoir 1 d'. In this example said third ligands, optionally diluted in acetate buffer, is provided in the fourth reservoir 1d'.

[00132] Ligands of a fourth type (referred to hereafter as fourth ligands) are provided in the fifth reservoir 1e. In this example said fourth ligands, optionally diluted in acetate buffer, are provided in the fifth reservoir 1e.

[00133] A second immobilization reagent is provided in at least one of the remaining reservoirs 1 f-h in said row. In this example the second immobilization reagent comprises Ethanolamine, however it will be understood that the second immobilization reagent may take any suitable form. In this example the second immobilization reagent is provided in the sixth reservoir 1f of said row.

[00134] Optionally a buffer fluid is provided in the seventh and eight reservoirs 1 g, 1 h of said row. [00135] The carrier module 102 is moved into its first position.

[00136] Each of the pumping means 13a-h is then operated to provide a negative pressure. Each of the pumping means 13a-h may be operated simultaneously, or, alternatively, each of the pumping means 13a-h may be operated consecutively. The negative pressure causes a pickup volume of the respective sample fluids which are present in the reservoirs 1 a-h, to be each aspirated into the respective hollow needle 2a-h in the needle unit 2. Accordingly, after this step has been performed, the first immobilization reagent is contained in the first hollow needle 2a, the first ligands are contained in the second hollow needle 2b, the second ligands are contained in the third hollow needle 2c, the third ligands are contained in the fourth hollow needle 2d, the fourth ligands are contained in the fifth hollow needle 2e, the second immobilization reagent is contained in the sixth hollow needle 2f, and optionally a buffer fluid is contained in the seventh and eighth hollow needles 2g-h. [00137] The carrier module 102 is then moved to its second position.

[00138] The second selector valve 6 is then arranged into its fifth configuration, so that all of the first, second, third and fourth valves 6a-d are opened. [00139] The first pumping means 13a is then operated to provide a positive pressure.

[00140] Accordingly, the first immobilization reagent will flow from the first hollow needle 2a through the first socket 105a and through the first, second, third and fourth flow cells 3a-d. When the first immobilization reagent flows through the first, second, third and fourth flow cells 3a-d, the first immobilization reagent will contact the test surfaces of each flow cell 3a-d, thereby activating the respective test surfaces.

[00141] The first pumping means 13a is then operated to stop providing positive pressure. [00142] The second selector valve unit 6 is arranged into its first configuration so that the first valve 6a is opened and the second, third, fourth valves 6b-d are closed.

[00143] The second pumping means 13b is then operated to provide a positive pressure. [00144] Accordingly, the first ligands which are present in the second hollow needle 2b, pass through the second socket 105b into the first flow cell 3a only.

[00145] As the first ligands flow through the first flow cell 3a they will become attached to the test surface of the first flow cell 3a (the first immobilization reagent which flowed over the test surface of the first flow cell 3a in the preceding step primed the test surface of the first flow cell 3a so that the first ligands will attach to first immobilization reagent which is present on the test surface of the first flow cell 3a when the first ligands flow over the test surface of the first flow cell 3a; in other words the first ligands will be indirectly attached to the test surface of the first flow cell 3a via the first immobilization reagent which is present on the test surface of the first flow cell 3). Accordingly the test surface of the first flow cell 3a is thus provided with the first ligands which can bind to a predefined molecule.

[00146] Optionally, the sensor 103' is used to monitor the amount of first ligands which attach to the test surface of the first flow cell 3a. This can be done by recording the signal output by the sensor 103' as the first ligands flow through the first flow cell 3a.

[00147] The second pumping means 13b is then operated to stop providing positive pressure.

[00148] The second selector valve unit 6 is arranged into its second configuration so that the first second valve 6b is opened and the first valve 6a, and third and fourth valves 6c-d, are closed.

[00149] The third pumping means 13c is then operated to provide a positive pressure.

[00150] Accordingly, the second ligands which are present in the third hollow needle 2c, pass through the third socket 105c into the second flow cell 3b only.

[00151] As the second ligands flow through the second flow cell 3b they will become attached to the test surface of the second flow cell 3b (the first immobilization reagent which flowed over the test surface of the second flow cell 3b in the preceding step primed the test surface of the second flow cell 3b so that the second ligands will attach to the second

immobilization reagent which is present on the test surface of the second flow cell 3b when the second ligands flow over the test surface of the second flow cell 3b; in other words the second ligands will be indirectly attached to the test surface of the second flow cell 3b via the second immobilization reagent which is present on the test surface of the second flow cell 3b). Accordingly the test surface of the second flow cell 3b is thus provided with the second ligands which can bind to a predefined molecule. [00152] Optionally, the sensor 103' is used to monitor the amount of second ligands which attach to the test surface of the second flow cell 3b. This can be done by recording the signal output by the sensor 103' as the second ligands flow through the second flow cell 3b.

[00153] The third pumping means 13c is then operated to stop providing positive pressure.

[00154] The second selector valve unit 6 is arranged into its third configuration so that the third valve 6c is opened and the first, second, and fourth valves 6a,b,d are closed.

[00155] The fourth pumping means 13d is then operated to provide a positive pressure.

[00156] Accordingly, the third ligands which are present in the fourth hollow needle 2d, pass through the fourth socket 105d into the third flow cell 3c only.

[00157] As the third ligands flow through the third flow cell 3c they will become attached to the test surface of the third flow cell 3c (the first immobilization reagent which flowed over the test surface of the third flow cell 3c in the preceding step primed the test surface of the third flow cell 3c so that the third ligands will attach to the third immobilization reagent which is present on test surface of the third flow cell 3c when the third ligands flow over the test surface of the third flow cell 3c; in other words the third ligands will be indirectly attached to the test surface of the third flow cell 3c via the third immobilization reagent which is present on the test surface of the third flow cell 3c). Accordingly the test surface of the third flow cell 3c is thus provided with the third ligands which can bind to a predefined molecule.

[00158] Optionally, the sensor 103' is used to monitor the amount of third ligands which attach to the test surface of the third flow cell 3c. This can be done by recording the signal output by the sensor 103' as the third ligands flow through the third flow cell 3c.

[00159] The fourth pumping means 13d is then operated to stop providing positive pressure.

[00160] The second selector valve unit 6 is arranged into its fourth configuration so that the fourth valve 6d is opened and the first, second, and third valves 6a,b,c are closed.

[00161] The fifth pumping means 13e is then operated to provide a positive pressure.

[00162] Accordingly, the fourth ligands which are present in the fifth hollow needle 2e, pass through the fifth socket 105e into the fourth flow cell 3d only.

[00163] As the fourth ligands flow through the fourth flow cell 3d they will become attached to the test surface of the fourth flow cell 3d (the first immobilization reagent which flowed over the test surface of the fourth flow cell 3d in the preceding step primed the test surface of the fourth flow cell 3d so that the fourth ligands will attach to the fourth immobilization reagent which is present on the test surface of the fourth flow cell 3d when the fourth ligands flow over the test surface of the fourth flow cell 3d; in other words the fourth ligands will be indirectly attached to the test surface of the fourth flow cell 3d via the fourth immobilization reagent which is present on the test surface of the fourth flow cell 3d). Accordingly the test surface of the fourth flow cell 3d is thus provided with the fourth ligands which can bind to a predefined molecule. [00164] Optionally, the sensor 103' is used to monitor the amount of fourth ligands which attach to the test surface of the fourth flow cell 3d. This can be done by recording the signal output by the sensor 103' as the fourth ligands flow through the fourth flow cell 3d. [00165] The fifth pumping means 13e is then operated to stop providing positive pressure.

[00166] The second selector valve unit 6 is arranged into its fifth configuration so that all of the first, second, third and fourth valves 6a-d are opened. [00167] The sixth pumping means 13f is then operated to provide a positive pressure.

[00168] Accordingly, the second immobilization reagent which is present in the sixth hollow needle 2f, passes through the sixth socket 105f into all of the flow cells 3a-d. [00169] When the second immobilization reagent flows through the first, second, third and fourth flow cells 3a-d, the second immobilization reagent will act to passivate the test surfaces of the respective first, second, third and fourth flow cells 3a-d.

[00170] The sixth pumping means 13e is then operated to stop providing positive pressure.

[00171] Optionally, the second selector valve unit 6 is maintained in its fifth configuration.

[00172] Optionally, the seventh pumping means 13g is then operated to provide a positive pressure. [00173] Accordingly, the buffer fluid which is present in the seventh hollow needle 2g, passes through the seventh socket 105g into all of the flow cells 3a-d. When the buffer flows through the first, second, third and fourth flow cells 3a-d, the buffer will act to equilibrate the test surfaces within the flow cells 3a-d. In the present invention equilibrate a test surface means to stabilize the test surface in order to reduce drift effects on the sensor readout.

[00174] The seventh pumping means 13g is then operated to stop providing positive pressure.

[00175] Optionally, the second selector valve unit 6 is maintained in its fifth configuration. [00176] Optionally, the eighth pumping means 13h is then operated to provide a positive pressure.

[00177] Accordingly, the buffer fluid which is present in the eight hollow needle 2h, passes through the eighth socket 105h into all of the flow cells 3a-d. When the buffer flows through the first, second, third and fourth flow cells 3a-d, the buffer will act to equilibrate the test surfaces within the flow cells 3a-d.

[00178] It should be understood that the flow cell unit 3 used in any of the above-mentioned assembly embodiments may be provided in a cartridge which can be selectively removed from the assembly; the cartridge may be a disposable cartridge for example. It should be

understood that the cartridge may take any suitable form; however, the cartridge will always contain the flow cells 3a-d of the flow cell unit 3.

[00179] Fig. 4 provides the bottom view of portion of an exemplary cartridge. In this example the cartridge 139 is a disposable cartridge.

Referring to Figure 4 there is shown the flow cells 3a-d of the flow cell unit 3 provided in the disposable cartridge 139. The flow cells 3a-d are integral to the disposable cartridge 139. When the flow cells 3a-d of the cartridge become damaged or non-useable the cartridge is simply removed, and a new cartridge is provided in the assembly. [00180] Fig. 3a provides a perspective view of a portion of the disposable cartridge 139 and Fig. 3b provides a perspective view of an exemplary plunger assembly 140, wherein the disposable cartridge 139 and plunger assembly140 can mechanically cooperate with one another; the disposable cartridge 139 and plunger assembly140 can be used in any of the above- mentioned assemblies.

[00181] Figure 3a shows a partial perspective-top view of the cartridge 139, which can be used in any of above-described assemblies to define the flow cell unit 3. The cartridge 139 comprises fluidic interfaces 150-165 .

Each fluidic interface 150-165 comprises a ring member made of an elastomeric compound such as EPDM, FKM or silicone. Figure 3b shows a perspective-bottom view of a plunger assembly 140 which is fixed part of the assembly. The plunger assembly 140 is suitable for cooperating with the cartridge 139. The plunger assembly 140 further comprises fluidic channels 190 having positions corresponding the positions fluidic interfaces 150-165 provided in the cartridge 139; the respective rim at the open end of each fluidic channel 190 defines a corresponding interface 166-181. The number of fluidic channels preferably corresponds to the number of fluidic interfaces 150-165 provided on the cartridge.

[00182] The cartridge 139 comprise a main body 141, the main body 141 may be injected molded, preferably comprising a thermoplastic material such as Polycarbonate or Cyclic Olefin CopolymerPreferably the plunger assembly comprises hard and inert material with high resistance to chemicals, for example precision machined or polished stainless steel or PEEK.

[00183] The plunger assembly 140 comprises linear bearings 143 which allow it to be movable in a direction perpendicular to the plane of fluidic interfaces 150-165 of the cartridge 139; in particular, the plunger assembly 140 can be moved to abut the cartridge 139 so as to bring the respective rim at the open end of each fluidic channel 190 which defines a

corresponding interface 166-181, into abutment with a corresponding ring member with defines a respective fluidic interface 150-165 on the cartridge. The plunger assembly 140 and cartridge 139 may be maintained in such a position (i.e. a position where by the interfaces are aligned and abut) by means of a pinion such as a stainless steel bolt, or a spring.

[00184] Preferably, the plunger assembly 140 is positioned in the assembly so that the respective rims at the open end of each fluidic channel 190 which defines a corresponding interface 166-181, abut respective ring members on the cartridge 139 with define respective fluidic interface I SO- 165 form a fluid-impermeable seal between the fluidic interfaces 150-165 on the cartridge 139 and the fluidic interfaces 166-181on the plunger assembly 140. Preferably the plunger assembly 140 is positioned so that the respective rims at the open end of each fluidic channel 190 which defines a corresponding interface 166-181, compress respective ring members on the cartridge 139 with define respective fluidic interface 150-165 form a fluid- impermeable seal between the fluidic interfaces 150-165 on the cartridge 139 and the fluidic interfaces 166-181on the plunger assembly 140. As an example, the respective rim at the open end of the fluidic channel 190 which defines a fluidic interface 174 is pressed onto the small rings forming the ninth fluidic interface 158, thereby combining and sealing the cartridge part of the second conduit 15 and the fixed parts of the second conduit 15. When moving the plunger assembly 140 away from the cartridge, the fluidic interfaces are separated allowing easy removal and disposable and replacement of the cartridge 139.

[00185] In the depicted embodiment, the fluidic interfaces 150-165 on the cartridge 139 comprise rings of elastomeric material; preferably the rings are provided as a sinnle substrate and that sinnle substrate is attached to the main body 141 of the cartridge 139; the centre of each ring is aligned with a respective hole which is defined in the main body 141. In a further preferred embodiment, the fluidic interfaces 150-165 are formed integral to the main body 141 of the cartridge 139; in such an embodiment the main body 141 and the fluidic interfaces 150-165 may both be formed from a single injection molded part; the single injection molded part may comprise dual materials and integrated elastomeric ring seals. [00186] Various modifications and variations to the described

embodiments of the invention will be apparent to those skilled in the art without departing from the scope of the invention as defined in the appended claims. Although the invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiment.