Apparatus for maintaining separation of liquids, and method of using the same to process a sample

Abstract

The present disclosure relates to apparatus for extracting a chemical or biological species from a sample, comprising: a first liquid in a first region; a second liquid in a second region, wherein the

Description

Field of the Invention The invention relates to apparatus and methods for extracting biomolecules, or other chemical or biological species, from a sample for subsequent testing or analysis. Merely by way of example, the invention may be used for, but is by no means limited to, maintaining separation of liquids used to extract targeted biomolecules from a swab sample. The term “magnetic beads” as used herein should be interpreted broadly. Firstly, the term “magnetic” should be interpreted broadly, to encompass “paramagnetic” and “superparamagnetic”. Moreover, the term “beads” (or “particles”) should also be interpreted broadly, to encompass particles of a range of sizes, including nanoparticles (i.e. particles that are less than 1 pm in diameter), micron-sized particles (i.e. of the order of 1 to 500 pm in diameter), and larger particles (potentially up to around 1 mm or so in diameter). As those skilled in the art will appreciate, the principles of the present disclosure are not limited to any particular size, shape or composition of the magnetic “beads”, and for any given application it will be understood that the skilled person could use beads of a suitable size, shape, composition, coating and functionalisation. Background to the Invention Magnetic beads can be used in methods for extracting targeted biomolecules from a sample. Magnetic beads typically comprise two components: a magnetic material (often iron, an iron oxide such as magnetite, nickel, or cobalt) and a coating that enables the beads to attach to biomolecules or other chemical or biological species. Such species may include, but are not limited to, polynucleotides such as nucleic acid (e.g. RNA or DNA), proteins, biological cells, and other chemical or biological molecules. Methods of extracting the target species from the biological sample often use multiple different liquids or buffers to extract and prepare the species for downstream analysis. For example, a lysis buffer can be used to break down a sample and release DNA, RNA or proteins from cells (or, for example, viral capsids), to then be bound to the coating of magnetic beads. A wash liquid may then be used to remove the lysis buffer and any unwanted biological material from the beads (e.g, without affecting the DNA / RNA / proteins bound to the beads). An elution liquid is then used to elute (release) the target species from the beads into the elution liquid, for subsequent analysis or processing. Whilst magnetic beads are not the only tool that can be used in conjunction with the aforementioned buffers to extract, isolate, and purify targeted biomolecutes, they offer a convenient solution due to their high surface area and ability to be manipulated with a magnetic field, thus enabling their selective separation from the buffers. Commonly, the magnetic beads and attached biomolecules are either moved through a series of vessels or tubes containing the buffers, or the buffers are added to and removed from a single vessel or tube, with the magnetic beads being selectively retained in the tube using a magnetic field that is often produced using a stationary magnet. Due to the large number of different buffers and steps that is often needed to extract a target molecule from a sample using magnetic beads, such methods are typically used in a laboratory environment and involve the use of numerous tubes, micropipettes, mixing devices, and a significant level of training. However, it is often desirable, especially in the case of diagnostic testing, for this process to be performed either at the point-of-care or by untrained users. Therefore, there is a need for a portable and automatable solution. Recent methods utilise immiscible fluids to separate the different buffers from one another, and utilise a magnet to transport magnetic beads through the buffers. Whilst this method has potential to simplify the extraction process by eliminating the need to completely separate the magnetic beads from each buffer in turn, it possesses a number of significant technical challenges for adaptation to point-of-care applications. For example, there is a problem that even when immiscible liquids are used to maintain separation of the reagents, the liquids are nevertheless prone to inadvertent mixing. Such unwanted mixing can be caused by vibrations induced by transport. Contamination of the elution liquid due to leakage of the lysis buffer or wash liquid (e.g. ethanol) can seriously disrupt any test or analysis performed on the eluted species. Moreover, this sensitivity to inadvertent mixing can limit the options for introducing a sample, particularly for the case of a swabbed specimen, since agitation used to release biological material from the swab can disturb the separation of the reagents. The use of surface tension to maintain separation between immiscible liquids also results in restrictions on the surface area at each liquid-liquid interface in order to maintain the separation, which can limit the usable volume of each buffer (or the sample input), potentially decreasing performance. This is particularly an issue when working with ‘dirty’ or complex sample types with large quantities of unwanted material. It will be appreciated, therefore, that there is a need for improved apparatus and methods for mitigating against one or more of the above issues to provide a more reliable, automatable, portable and high performing solution for the extraction of a biomolecule, or other chemical or biological species, from a sample. Summary of the Invention Aspects of the present invention are set out in the appended independent claims, while details of certain embodiments are set out in the appended dependent claims. In a first aspect the invention provides apparatus for extracting a chemical or biological species from a sample, the apparatus comprising: a first liquid in a first region; a second liquid in a second region, wherein the second liquid is immiscible with the first liquid; and beads for transporting the chemical or biological species; wherein the apparatus is configurable between: a first configuration in which there is a path for transport of the beads from the first liquid in first region to the second liquid in the second region, and a second configuration in which a barrier is provided between the first region and the second region. Beneficially, when the apparatus is in the first configuration the beads can be transported from the first liquid and into the second liquid, and when the device is in the second configuration the barrier between the first region and the second region helps to prevent the liquids in the apparatus from mixing (for example, due to vibrations during transport of the apparatus). The term barrier is to be interpreted broadly. When the apparatus is in the second configuration there may be no interface between the first liquid in the first region and the second liquid in the second region. When the apparatus is in the second configuration there may be no path for transport of the beads from the first liquid in the first region and into the second liquid in the second region. The second region may be provided within a first rotating valve; the apparatus may be operable for rotation of the first rotating valve between an open position corresponding to the first configuration and a closed position corresponding to the second configuration; when the first rotating valve is in the open position there may be a path for transport of the beads from the first liquid in first region to the second liquid in the second region; and when the first rotating valve is in the closed position, a wall of the first rotating valve may form the barrier. Beneficially, the rotating valves are particularly leak resistant, and provide a particularly compact arrangement. The apparatus may further comprise a third liquid in a third region; wherein the third liquid is immiscible with the second liquid; wherein when the apparatus is in the first configuration there is a path for transport of the beads from the second liquid in the second region to the third liquid in the third region; and wherein when the apparatus is in the second configuration a barrier is provided between the second region and the third region. When the first rotating valve is in the open position, the beads may be transported from the first liquid in the first region to the third liquid in the third region via the second liquid in the second region. The third liquid may comprise a wash buffer. The first rotating valve may comprise a fifth port provided on an upper surface of the first rotating valve; and the apparatus may be configured, when the first rotating valve is in the closed position, for flow of the third liquid into the fifth port to fill the third liquid in the third region. The apparatus may further comprise: a fourth liquid in a fourth region; and a fifth liquid in a fifth region; wherein the fourth region is provided within a second rotating valve; wherein the apparatus is operable for rotation of the second rotating valve between an open position corresponding to the first configuration and a closed position corresponding to the second configuration; wherein when the second rotating valve is in the open position there is a path for transport of the beads from the third liquid in third region to the fifth liquid in the fifth region via the fourth liquid in the fourth region; wherein when the second rotating valve is in the closed position a wall of the second rotating valve forms a barrier between the third region and the fourth region; and wherein when the second rotating valve is in the closed position the wall of the second rotating valve forms a barrier between the fourth region and the fifth region. The first rotating valve and the second rotating valve may be rotated either simultaneously or sequentially to configure the apparatus between the first configuration and the second configuration. The third liquid and the fourth liquid may be immiscible; and the fourth liquid and the fifth liquid may be immiscible. The fourth liquid may comprise oil and the fifth liquid may comprise an elution buffer. The apparatus may be configured for sequential rotation of the first rotating valve and the second rotating valve to reconfigure the apparatus from the first configuration and into the second configuration, and to reconfigure the apparatus from the second configuration and into the first configuration. The second rotating valve may comprise a sixth port provided on an upper surface of the second rotating valve; and the apparatus may be configured, when the second rotating valve is in the closed position, for flow of the third liquid out of the third region and out of the sixth port. The apparatus may be configured for flow of the third liquid out of the apparatus via the sixth port as the third liquid flows into the third region via the fifth port. Advantageously, the flow of the third liquid (e.g. wash buffer) out of the apparatus as the third liquid flows into the third region via the fifth port beneficially reduces the occurrence of air bubbles becoming trapped inside the third liquid in the apparatus that could inhibit the transport of the beads along the apparatus. Alternatively, the fifth port may be provided on a side of the apparatus at a location other than the upper surface of the first rotating valve, and the sixth port may be provided on a side of the apparatus at a location other than the upper surface of the second rotating valve. The first liquid may comprise a lysis buffer and the second liquid may comprise oil. The beads may be magnetic beads. The apparatus may be configured for receiving the sample in the first region, wherein the sample is a liquid sample. The apparatus may be configured for receiving the sample in the first region; wherein receiving the sample in the first region comprises receiving a swab tip in the first region. The apparatus may comprise a swab-supporting member arranged for preventing the swab tip from engaging with a base of the first region. By virtue of the swab supporting member, the tip of the swab is beneficially prevented from being pushed against the base of the first region (or from being pushed too far into the cartridge towards the second region) by a user, reducing the risk of mucous or other viscous material from the swab (that could cause the beads to become stuck) from being transferred to the base of the region. Moreover, by virtue of the provision of the swab-supporting member, movement of the swab tip that could disturb the liquidliquid interfaces between the immiscible fluids is reduced (or prevented). The apparatus may be configured such that, in use, the first liquid in the first region may cover the swab-supporting member when the apparatus is in a generally vertical orientation, and the first liquid in the first region may not cover the swab-supporting member when the apparatus is in a generally horizontal orientation. Beneficially, therefore, the chemical or biological species can be eluted by covering the swab tip with the first liquid when the apparatus is in the vertical orientation, and the beads can be transported along the apparatus (e.g. using a magnetic field) when the apparatus is in the generally horizontal orientation (and the level of the first liquid is below that of the swab-supporting member), reducing the risk that beads will encounter the swab-supporting member and become stuck to mucous or other viscous material that was transferred to the swab-supporting member from the swab (or become stuck to the swab itself). It will be appreciated that the swab tip need not necessarily remain inside the apparatus and could be removed before the apparatus is moved into the generally horizontal orientation. Alternatively, the swab tip could remain in the apparatus. As will be described in more detail later, the swab tip may be broken away from the remainder of the swab and remain inside the apparatus. The apparatus may be configured such that, in use, when the swab tip is in the first region: the first liquid in the first region covers the swab tip when the apparatus is in a generally vertical orientation, and the first liquid in the first region does not cover the swab tip when the apparatus is in a generally horizontal orientation. The first region may have a tapered shape along the longitudinal length of the apparatus. By virtue of the tapered shape of the region that contains the first liquid (e.g. lysis buffer), the level of the first liquid is advantageously below the level of the swab tip when the apparatus is in the generally horizontal orientation, but covers the swab tip when the apparatus is in a generally vertical orientation. Moreover, as a result of the tapered shape of the first region, the depth of the first liquid is relatively small when the apparatus is in the horizontal orientation, and therefore when a magnet below the first region is used to transport the beads, the beads in the first liquid are beneficially located closer to the magnet, increasing the force exerted on the beads by the magnet and reducing the strength of magnet needed. The tapered shape also enables improved mixing of the beads within the majority of the liquid, rather than the beads only mixing with a small percentage of the liquid if the floor surface area is small relative to the depth / height of the liquid. The apparatus may further comprise: a first O-ring that is arranged at an interface between the first region and the first rotating valve; a second O-ring arranged at an interface between the first rotating valve and the third region; a third O-ring arranged at an interface between the third region and the second rotating valve; and a fourth O-ring arranged at an interface between the second rotating valve and the fifth region. The first rotating valve may be arranged for rotation within a sixth region, and the second rotating valve may be arranged for rotation within a seventh region; wherein the first O-ring and the second O-ring are arranged between the wall of the first rotating valve and a wall of the sixth region; and wherein the third O-ring and the fourth O-ring are arranged between the wall of the second rotating valve and a wall of the seventh region. A region between the first rotating valve and a wall of the sixth region may contain the second liquid; and a region between the second rotating valve and a wall of the seventh region may contain the fourth liquid. By virtue of the region of second liquid between the first rotating valve and a wall of the sixth region (and the region of the fourth liquid between the second rotating valve and the wall of the seventh region), the risk of the other liquids leaking from the apparatus is reduced, and the evaporation of the other liquids from the cartridge is inhibited. The second and fourth liquids (which may be oil) may also provide lubrication, enabling the rotating valves to be rotated more easily within their respective regions. The apparatus may further comprise a fifth O-ring arranged around the first rotating valve and a sixth O-ring arranged around the second rotating valve; wherein the fifth O-ring is arranged to seal the second liquid in the sixth region; and wherein the sixth O-ring is arranged to seal the fourth liquid in the seventh region. The first O-ring and the second O-ring may be engaged with a wall of the first rotating valve, and the third O-ring and the fourth O-ring may be engaged with a wall of the second rotating valve; wherein the wall of the first rotating valve and the wall of the second rotating valve are each angled such that a compressive force is applied to each of the first O-ring, the second O-ring, the third O-ring and the fourth O-ring. Advantageously, by virtue of the angled orientation of the walls of the rotating valves, the force from the rotating valves pushing against the O-rings has a horizontal component (along the longitudinal direction of the apparatus) that is adjustable based on an amount of downward force applied to the rotating valves, further improving the strength of the seals, and enabling the strength of the seals to be configurable based on an amount of downward force applied to the rotating valves. The first rotating valve and the second rotating valve may have a conical or wedge shape, thereby providing the angled walls that engage with the first O-ring, the second O-ring, the third O-ring and the fourth O-ring. The first rotating valve may comprise a first groove or first protrusion in an upper surface of the first rotating valve for engaging with a first rotating member for rotating the first rotating valve; and the second rotating valve may comprise a second groove or second protrusion in an upper surface of the second rotating valve for engaging with a second rotating member for rotating the second rotating valve. When the apparatus is in the second configuration, the first groove or first protrusion may be aligned with the second groove or second protrusion. Advantageously, by virtue of the grooves being aligned when the rotating valves are in the closed positions, when the apparatus is inserted into an automated device for rotating the valves, members or tabs of the automated device can slot into the grooves as the apparatus is inserted into the automated device. Alternatively, rather than grooves, tabs (or any other suitable protrusion) may be provided on the upper surface of the rotating valves, and the tab of the first rotating valve may be aligned with the tab of the second rotating valve when the apparatus is in the second configuration. The apparatus may further comprise: a first port through which the second liquid can flow into the apparatus to fill the second region; and a second port through which the second liquid can flow out of the apparatus, and the apparatus may further comprise a port cover that is moveable between a filling position for filling of the second liquid into the second region, and a closed position for sealing the second liquid inside the apparatus; wherein when the port cover is in the filling position, a first aperture of the port cover is aligned with the first port, and a second aperture of the port cover is aligned with the second port. The first aperture and the second aperture may be configured such that as the port cover is moved into the closed position, one of the first port or the second port is sealed closed by the port cover before the other of the first port or the second port is sealed closed by the port cover. Advantageously, by virtue of the port cover sealing one of the ports closed before the other port is sealed closed, excess pressure build-up in the second liquid (e.g. oil, which is an incompressible liquid) that can occur as the ports are sealed closed is beneficially reduced, since the excess pressure can be released via ejection of the second liquid out of the port that is sealed last. One of the first aperture or the second aperture may be circular, and the other of the of the first aperture or the second aperture may have an elongate shape. The first port may be further configured for flow of the second liquid into the sixth region. The apparatus may be configured to allow flow of the second liquid out of the apparatus via the second port as the second liquid flows into the second region via the first port. Advantageously, the flow of the second liquid (e.g. oil) out of the apparatus as the second liquid flows into the second region via the first port beneficially reduces the occurrence of air bubbles becoming trapped inside the second liquid inside the apparatus that could inhibit the transport of the beads along the apparatus. In other words, by virtue of the provision of the two ports for filling the second liquid, a flow of oil can be pushed into (and out of, via the other port) the apparatus, reducing the risk of air bubbles becoming trapped, since air is allowed to vent out of the second port. The apparatus may further comprise: a third port through which the fourth liquid can flow into the apparatus to fill the fourth region; a fourth port through which the fourth liquid can flow out of the apparatus; and a corresponding port coverthat is moveable between a filling position for filling of the fourth liquid into the fourth region, and a closed position for sealing the fourth liquid inside the apparatus; wherein when the port cover is in the filling position, a first aperture of the port cover is aligned with the third port, and a second aperture of the port cover is aligned with the fourth port. The third port may be further configured for flow of the fourth liquid into the seventh region. The apparatus may be configured to allow flow of the fourth liquid out of the apparatus via the fourth port as the fourth liquid flows into the fourth region via the first port. The third aperture and the fourth aperture may be configured such that as the corresponding port cover is moved into the closed position, one of the third port or the fourth port is sealed closed by the port cover before the other of the third port or the fourth port is sealed closed by the port cover. The apparatus may further comprise at least one gas region, and the gas region may be arranged such that gas inside the gas region compresses as the pressure of the second liquid inside the second region increases. The apparatus may further comprise at least one foam disc, and the foam disc may be arranged such that the foam disc compresses as the pressure of the second liquid inside the second region increases. Advantageously, increases in pressure of the second liquid causes gas (e.g. air) in the gas region (e.g. bubble trap), or the foam disc, to compress, beneficially relieving some of the pressure in the second liquid (e.g. oil) that can occur as the second liquid is sealed inside the apparatus. Pressure in the second liquid can also occur due to temperature fluctuations during storage or operation of the apparatus. Alternatively, or additionally, the apparatus may comprise a region of compressible liquid, adjacent to the second liquid, for relieving some of the pressure in the second liquid. A base of the apparatus (e.g. a base of the first region) may be configured to impart a vertical force component on the beads as the beads are transported longitudinally along the apparatus (e.g. through the first liquid in the first region towards the second liquid in the second region). The base of the first region may comprise an undulating surface. A base of the first region may comprise ridges, steps, ribs, or a wave-like surface. The base of the first region may comprise ribs, a wave-like surface, or an undulating surface. The base of the first region may comprise a series of grooves or indentations. By virtue of the ridges, steps, ribs, grooves or indentations, mixing of the beads in the first liquid (e.g. lysis buffer) as the beads are transported along the apparatus is improved, reducing the amount of clumping and increasing the surface area of the beads exposed to the first liquid. The base of the first region may be configured such that horizontal forces on the beads (e.g. induced using a magnetic field) result in upward motion of the beads, improving mixing of the beads with upper regions of the first liquid further away from the base of the first region. The apparatus may further comprise a plunger for ejecting the fifth liquid from the fifth region via a corresponding aperture. The apparatus may be configured for receiving the sample in the first region via an opening into the first region; wherein the apparatus comprises a wall inside the first region that defines a sample receiving region that extends from the opening, for receiving the sample; and wherein the wall is configured for preventing the first liquid from flowing out of the opening when the apparatus is in a generally horizontal orientation. The wall may be configured for preventing the first liquid from flowing out of the opening when the apparatus is inverted (when the opening is facing generally downward). Advantageously, the wall helps to prevent the liquid from spilling from the apparatus. In other words, the wall is an anti-spill wall. The apparatus may be a cartridge for insertion into an automated device for selectively configuring the cartridge into the first configuration or the second configuration and for extracting the chemical or biological species from the cartridge. The automated device may configure the cartridge into the first configuration or the second configuration by rotating the first rotating valve and the second rotating valve either simultaneously or sequentially. The automated device may engage with the plunger to eject the fifth liquid from the fifth region via the corresponding aperture. In a second aspect the invention provides a method of extracting a chemical or biological species from a sample, the method comprising: receiving the sample in the first region of the apparatus according to the first aspect; eluting the chemical or biological species from the sample using the first liquid in the first region; configuring the apparatus to be in the first configuration; and transporting the beads from the first liquid in the first region and into the second liquid in the second region. In a third aspect the invention provides a method of extracting a chemical or biological species from a sample, the method comprising: receiving the apparatus of the first aspect into the automated device; reconfiguring the cartridge into the first configuration from the second configuration using the automated device; and transporting the beads from the first liquid in the first region and into the second liquid in the second region using the automated device. The method may comprise ejecting the fifth liquid from the fifth region via the corresponding aperture by using the automated device to actuate the plunger. In a fourth aspect the invention provides a method of filling the apparatus according to the first aspect with the second liquid, the method comprising: moving the port cover into the filling position; and providing a flow of the second liquid through the first port, for flow of the second liquid out of the second port via the second region. Advantageously, the flow of the second liquid into one of the ports and out of the other port provides a flow of the second liquid through the second region to fill the second region, which reduces the risk of air bubbles becoming trapped inside the second region during the fill process. The method may comprise using one or more syringes or pumps to drive the flow of the second liquid through the first port. The method may comprise providing a first flow configuration for flow of the second liquid through the first port, for flow of the second liquid out of the second port via the second region; and providing a second flow configuration for flow of the second liquid through the second port, for flow of the second liquid out of the first port via the second region; wherein the method further comprises alternating between the first flow configuration and the second flow configuration. Advantageously, by virtue of the alternating filling between the first flow configuration and the second flow configuration, the occurrence of air bubbles becoming trapped within the second region is further reduced. The method may further comprise moving the port cover into the closed position after the second region has been filled with the second liquid. Brief Description of the Drawings Embodiments of the invention will now be described by way of example only with reference to the attached figures in which: Figure 1a schematically illustrates a series of liquids used to extract a biomolecule from a sample for subsequent testing or analysis; Figure 1b illustrates transport of magnetic beads through the liquids in a tube, showing a magnet in a first position, and the magnet having been moved along the length of the tube to a second position; Figure 2a schematically illustrates an arrangement of valves use to maintain separation of the liquids; Figure 2b shows a modification of the arrangement of Figure 2a; Figure 3 shows a cross section of a cartridge according to one example; Figure 4a shows a perspective view of the cartridge; Figure 4b shows a further perspective view of the cartridge in which a lid of the cartridge is open: Figure 5 shows a cross section of a modified version of the cartridge in which a swab can be screwed into the cartridge; Figure 6 shows a further perspective view of the cartridge; Figure 7 shows a top-down view of the cartridge; Figure 8 shows a view of a side of the cartridge from which oil is filled; Figure 9 shows a view of the underside of the cartridge; Figure 10 illustrates a cutaway view of the cartridge showing the paths via which the device is filled with oil; Figure 11 illustrates a cutaway view of the cartridge showing ports via which the device is filled with oil; Figure 12 shows a further cross-sectional view of the cartridge; Figure 13 shows a further cross-sectional view of the cartridge; Figure 14 shows a cutaway view of the cartridge; Figure 15 shows a further cutaway view of the cartridge; Figure 16 shows a top-down cutaway view of the cartridge; Figure 17 shows a top-down view of a rotating valve of the cartridge; Figure 18 shows a perspective view of a rotating valve of the cartridge; Figure 19 shows a cutaway and exploded view of the cartridge; Figure 20 shows a further cutaway view of the cartridge; Figure 21a schematically illustrates a path of the beads through the lysis liquid; Figure 21 b shows a modification in which the chamber that contains the lysis liquid has a substantially flat base; Figure 22a shows the cartridge in an upright position in which the tip of a swab is covered by the lysis liquid; Figure 22b shows the cartridge in a horizontal position in which the level of the lysis liquid is below the tip of the swab; Figure 23 shows an exploded cross-sectional view of the cartridge; Figure 24 shows a cross-sectional view of O-rings and a rotating valve of the cartridge; Figure 25 shows a cross-sectional view a rotating valve of the cartridge when the rotating valve is in an open position; Figure 26 shows a cross-sectional view a rotating valve of the cartridge when the rotating valve is in a closed position; Figure 27 shows a cross-sectional view' of the cartridge, illustrating a path used to fill the device with the wash liquid; Figure 28 shows a cross-sectional view of the cartridge when the rotating valves are rotated by 45 degrees from the open position; Figure 29 shows a cross-sectional view of an end portion of the cartridge, showing a plunger; Figure 30 shows a further view of the plunger; Figure 31a shows a modified version of the cartridge in which air bubble traps are provided; Figure 31 b shows a further view of the air bubble traps; Figure 31c shows a modified version of the cartridge in which a foam disc is provided; Figure 31 d shows a further view of the foam disc; Figure 32 shows a cross-sectional view of apparatus for filling the cartridge with oil; Figure 33 shows a cross section of a modified cartridge in which linear sliding valves are used; Figure 34a shows a cross-cross sectional view of a modified cartridge in which membrane valves are used; Figure 34b shows a further cross-sectional view of the modified cartridge in which membrane valves are used; Figure 35 shows a further view of the modified cartridge in which membrane valves are used; Figure 36 shows a further view of the modified cartridge in which membrane valves are used; and Figure 37 shows a modified cartridge in which rotating valves are used. In the figures, like elements are indicated by like reference numerals throughout. Detailed Description of Preferred Embodiments The present embodiments represent the best ways known to the Applicant of putting the invention into practice. However, they are not the only ways in which this can be achieved. Liquid Separation An arrangement of liquids used to extract a biomolecule or other chemical or biological species from a sample, and general concepts related to maintaining separation of liquids, will now be described with reference to Figs. 1a and 1b. Fig. 1 a schematically illustrates a series of liquids used to extract a biomolecule from a sample. In this example three liquids, labelled ‘A’, ‘B’ and ‘C’, are arranged inside a tube 100. A group of magnetic beads 102 is illustrated inside liquid A. A separation liquid, labelled ‘D’, is arranged between liquids A and B, and between liquids B and C. The separation liquid is immiscible with each of liquids A, B and C. In other words, the separation liquid has a propensity to remain separated from, and not to mix with, liquids A, B and C. Therefore, by virtue of the provision of the separation liquid in between the other liquids, the other liquids are inhibited from mixing. A magnet 105 can be used to drive (push or pull) the magnetic beads along the tube 100, from liquid A to liquid C via the intermediate liquids B and D, as the magnet 105 moves longitudinally along the length of the tube 100 in the direction indicated by arrow A. The tube 100 provides a continuous transport path along which the beads can move. Therefore, a biological or chemical species can be easily and efficiently transported, on the surface of the beads, through each of the liquids. Turning now to Fig. 1b, in this example the tube 100 has a corresponding base portion 114, and the liquids comprise a lysis buffer 104, a wash buffer 106, and an elution buffer 108. Regions of oil 112 are provided in-between the other liquids for use as a separation liquid. The oil 112 is immiscible with the other liquids, and therefore inhibits mixing. A group of beads 102 is illustrated in a region of oil 112 adjacent to the lysis buffer 104 (which may also be referred to as a lysis liquid). In use, the beads 102 can be transported into the lysis buffer 104 under the influence of the magnet 105 that is positioned below the base portion 114 of the tube 100, by moving the magnet 105 in the direction A. The beads 102 can then be transported to the wash buffer 106 via the intermediate region of oil 112, by moving the magnet 105 further in the direction A. Advantageously, the intermediate section of oil 112 displaces the lysis buffer 104 from the surface of the beads 102, preventing transport of lysis buffer 104 into the wash buffer 106. The wash buffer 106 (which may also be referred to as a wash liquid) is for removing any remaining lysis buffer and / or unwanted biological or chemical material from the surface of the beads 102. The beads 102 are then transported from the wash buffer 106 and into the elution buffer 108 (which may also be referred to as an elution liquid) as shown in the figure, via the further intermediate region of oil 112, by moving the magnet 105 further in the direction A. The intermediate region of oil 112 displaces the wash buffer 112 from the beads 102 before the beads 102 pass into the elution buffer 108. This is particularly beneficial since the presence of certain components commonly found in wash buffers 112 (e.g. ethanol or certain salts) in the elution buffer can seriously disrupt any test or analysis performed on the eluted species. Advantageously, the provision of the oil 112 between the wash buffer 106 and the elution buffer 108 removes the need for a separate drying step (which is relatively time consuming) to remove the wash buffer 106 from the beads, improving the efficiency of the method. Whilst in the example of Fig. 1a two regions of separation liquid (D) and three additional liquids (A, B and C) are shown (and similarly in Fig. 1b), this need not necessarily be the case. Alternatively, for example, there may be only two additional liquids (e.g. liquids A and B) separated by a single region of the separation liquid (D). In a further alternative, the liquids may simply comprise two reagent liquids that are immiscible, in which case an additional separation liquid need not necessarily be provided between the reagent liquids. In a further alternative there may more than three liquids separated by regions of the separation liquid. For example, whilst two regions of separation liquid (D) are used to separate three additional liquids (A, B and C) in Fig. 1 a, alternatively three regions of separation liquid (D) could be used to separate four additional liquids (for example if there is an additional wash buffer). Whilst the separation liquid D is immiscible with each of liquids A, B and C and therefore inhibits mixing, mixing of the liquids may nevertheless occur when the liquids are subject to vibrations (e.g. during transport) or other strong forces. Some of the liquids (e.g. a lysis buffer) may contain a surfactant or detergent, which also destabilises the liquid-liquid interfaces and can result in unwanted mixing. Fig. 2a shows an improved configuration in which valves 120 are provided between each of the liquids, to mitigate against such mixing. As shown in Fig. 2a, a first valve 120a is provided between liquids A and D, a second valve 120b is provided between liquids D and B, a third valve 120c is provided between liquids B and D, and a fourth valve 120d is provided between liquids D and C. Each of the valves 120 can be initially set to a closed position in which liquids cannot pass through the valves 120, advantageously minimising the risk of the liquids mixing or leaking during transport. The valves 120 can then be opened to allow the magnetic beads 102 to pass between the liquids. It will be appreciated that even when valves 120 are provided as shown in Fig. 2a, use of the separation liquid D is nevertheless advantageous since it inhibits mixing of the other liquids when the valves 120 are in the open position, and helps to remove the previous liquid from the surface of the beads as the beads progress along the tube 100. Whilst Fig. 2a shows an example in which a valve 120 is provided at every interface between two different liquids, Fig. 2b shows an alternative in which the separation liquid D itself can transition to a solid state, to perform the function of a valve 120e. For example, wax (or any other suitable material that can transition between a liquid state and a solid state) may be used. The wax may initially be in a solid state in which the wax acts as a closed valve 120e, preventing mixing between liquids A and B, and between liquids B and C. The wax may then be heated to cause the wax to transition to a liquid state, enabling transport of the magnetic beads 102 from liquid A to liquid C, via liquid B, and via the intermediate regions of liquid wax. In any of the examples of Fig. 1a to Fig. 2b, the separation liquid D need not necessarily be oil 112 or liquid wax. Any other suitable liquid that is sufficiently immiscible with the other liquids could alternatively be used. Moreover, in some examples the buffers themselves may be sufficiently immiscible such that an additional separation liquid is not needed (however, the additional separation liquid may still be provided, for example to help remove the previous liquid from the surface of the beads 102 as the beads 102 progress along the tube 100). The liquids illustrated in Figs. 1a to 2b may be for an extraction process to be carried out in respect of targeted biomolecules from a liquid or solid sample. The targeted biomolecules may be, for example, polynucleotides such as nucleic acid (e.g. RNA or DNA). For example, the targeted biomolecule may be the characteristic RNA of a particular virus, such as, but not limited to, SARS-CoV-2. The method is not restricted to any particular size or composition of the magnetic beads 102. Indeed, for any given application it will be understood that the skilled person will use beads 102 of a suitable size and composition. Moreover, any other suitable method of transporting material from a sample through the liquids may be used (e.g. by pushing a sample on a swab tip through the liquids). However, use of magnetics beads 102 is particularly advantageous since the beads 102 provide a large surface area to be exposed to each of the liquids, and the small size of the beads 102 helps to avoid disturbing the liquid separation when the beads 102 are transported through the liquid interfaces. It will also be appreciated that the particular coating of the beads 102 used will depend on the specifics of the particular reactions and the target biomolecules. For example, the magnetic beads 102 may have a silica coating which binds with nucleic acids under certain buffer conditions. A method in which targeted biomolecules such as DNA / RNA / proteins are released from a sample and transported to the elution buffer 108 will now be described. The targeted biomolecules are first released from a sample using the lysis buffer 104, and are bound to the surface of the beads 102 (e.g. magnetic nanoparticles) present in the lysis buffer 104. The beads 102 need not necessarily be present in the lysis buffer 104 when the sample is introduced into the lysis buffer 104. For example, the beads 102 could initially be in the oil 112, and transported into the lysis buffer 104 after the sample has been inserted into the apparatus 200. Alternatively, for example, the beads 102 could be added into the lysis buffer 104 after the sample has been inserted, via the same aperture through which the sample was introduced. The beads 102 are then washed using the washing liquid 106, to remove contaminants / chemicals from the previous step, as well as unwanted biological molecules. Once the beads 102 have been washed, the purified analyte is eluted (released) from the beads 102 using the elution buffer 108 (e.g. molecular grade water, or Tris-EDTA (TE) buffer). The eluted analyte (e.g. RNA) may then be used for downstream molecular applications such as polymerase chain reaction (PCR) processing, isothermal amplifications, etc., according to the user’s particular requirements. It will be appreciated that “Tris” is short for tris(hydroxymethyl)aminomethane, and EDTA is an abbreviation of ethylenediaminetetraacetic acid. Thus, to perform the method, first, second and third liquids are used. In this example, the first liquid is a lysis / binding buffer liquid 104, for lysing the targeted biomolecules and thereby releasing them into solution, and binding the biomolecules to the magnetic beads; the second liquid 106 is a washing liquid; and the third liquid 108 is an elution liquid, for eluting the biomolecules. As shown in Figs. 1a to 2b, the first, second and third liquids may be separated by an additional separation liquid 112 (e.g. oil), to inhibit mixing and to aid with the removal of each previous buffer from the surface of the beads 102. The lysis / binding buffer liquid 104 may be, for example, based on guanidinium thiocyanate, and optionally includes a solvent such as isopropanol or ethanol. The washing liquid 106 for removing contaminants / chemicals from the previous steps, as well as unwanted biological molecules, may be, for example, a solution of 80% ethanol. The elution liquid 108 causes elution of the analyte in question (e.g. characteristic RNA of viral particles), for subsequent processing. In the present example, the elution corresponds to the separation of the target biomolecule from the surface of the beads 102. After the target biomolecules have been eluted, the magnetic beads 102 may be transported out of the elution liquid 108 (e.g. in the direction opposite to that indicated by arrow A), leaving only the eluted analyte in the elution liquid 108, for subsequent processing (e.g. nucleic acid amplification using PCR or LAMP methods). It will be appreciated that the reagents may comprise any suitable chemical substances, and are not limited to a lysis buffer 104, wash buffer 106, or elution buffer 108. Illustrative Example - Cartridge Particularly advantageous apparatus for maintaining separation of liquids used to process a sample will now be described, referring firstly to Figs. 3 to 4b. Figs. 3 to 4b show an example in which the liquids are housed within a cartridge 200. It will be appreciated that whilst the device of Figs. 3 to 4b will be referred to as a ‘cartridge’, the device 200 need not necessarily be for insertion into another device. The cartridge 200 may also simply be referred to as the ‘device’ 200 or ‘apparatus’ 200. In this example, a lysis buffer 104, wash liquid 106, elution buffer 108 and oil 112 are provided within the cartridge 200. However, as described above, the present invention is not limited to use of these particular liquids, and any other suitable liquids could alternatively be used. In use, magnetic beads 102 in the cartridge 200 can be transported from the lysis buffer 104 to the elution buffer 108 via the wash liquid 106, and via the intermediate sections of oil 112, using a magnetic force (for example, from a magnet or electromagnet). The present examples will be described with reference to the use of a magnet 105 to provide the magnetic force, but it will be appreciated that one or more electromagnets could alternatively be used (or a plurality of magnets 105 could be used rather than a single magnet 105). The lysis buffer 104 breaks open cells / tissues from the sample, and genetic material from the sample comes out into the solution. The pH and salt concentration of the lysis buffer 104 is such that DNA / RNA sticks to a silica surface of the magnetic beads 102. The magnetic beads may be nanoparticles, which advantageously have a large surface area to which the DNA / RNA can attach. In use, the magnetic beads 102 are transported from the lysis buffer 104 to the wash buffer 106 (comprised, for example, substantially of ethanol or another suitable solvent), via a region of oil 112, using a magnet 105. Beneficially, the oil 112 removes the lysis buffer 104 from the beads 102 before the beads 102 pass into the wash buffer 106. The wash buffer 106 removes (or dilutes) any remaining lysis buffer 104 from the beads 102, and can also remove other unwanted chemical or biological material from the surface of the beads 102. The beads 102 are then transported into the elution buffer 108 via a further region of oil 112. The oil 112 beneficially removes the wash buffer 106 from the surface of the beads 102 before the beads pass into the elution buffer 108. The pH and salt concentration of the elution buffer is such that the DNA / RNA separates (elutes) from the beads into the elution buffer 108. The elution buffer 108 containing the eluted species can then be output from the cartridge for subsequent processing (e.g. for performing a subsequent test or analysis on the elution buffer and the extracted / isolated molecules). The cartridge 200 comprises a first portion 202 and a second portion 204. The first portion 202 comprises a hinged door 206. In this example, the hinge 208 of the door 206 is located on the upper side of the cartridge 200, but it will be appreciated that this need not necessarily be the case and that any other suitable position for the hinge 208 could alternatively be used. The hinged door 206 is operable between the open position illustrated in Fig. 4b, and the closed position illustrated in Fig. 4a. In the open position, a swab can be inserted into the cartridge 200 via a corresponding aperture 205. Alternatively, for example, rather than inserting a swab the sample could be introduced into the cartridge 200 via the aperture 205 using a pipette. When the door 206 is in the closed position, the aperture 205 is sealed by a plug 209 provided on the door 206. The door 206 may be lockable in the closed position, or may be difficult to open (e.g. by configuring the edges of the door 206 to be substantially flush with the adjacent surface 207 when the door 206 is in the closed position), to prevent or inhibit re-opening of the door 206. Beneficially, this reduces the risk of contamination after a sample has been placed into the device 200, and also reduces the risk of lysis buffer 104 spilling out of the aperture 205 due to the door 206 being inadvertently opened. The device 200 may also be provided with a foil seal (not shown in the figure) covering the aperture 205, to further reduce the risk of contamination or spills. The foil seal is removed by the user before the swab is inserted through the aperture 205 (or before the sample is pipetted into the cartridge 200). Whilst in the present example the cartridge 200 is provided with a hinged door 206, this need not necessarily be the case. Alternatively, for example, a removeable screw cap could be used to provide access to the inside of the cartridge 200. Male or female threads could be provided around the aperture 205 for receiving and securing the screw cap. When the door 206 is in the open position a user may insert a sample through the aperture 205 and into a sample receiving cavity 210, by inserting a swab through the aperture 205. The sample may be, for example, a nasal secretion that has been collected using a nasopharyngeal swab. The sample receiving cavity 210 is defined by a cavity wall 211, and leads to a swab supporting member 212 (which may also be referred to as a swab support 212, or swab guard 212). Throughout the description the term cavity is to be interpreted broadly to encompass a corresponding ‘volume’ or ‘region’. For example, the sample receiving cavity 210 may also be referred to as the sample receiving volume 210 or sample receiving region 210. The first portion 202 of the cartridge 200 contains a lysis buffer 104 in a corresponding cavity 309. Advantageously, the cavity wall 211 of the sample receiving cavity 210 functions as a spill guard that protects against the lysis buffer 104 spilling from the cartridge 200 when the door 206 is in the open position. When the cartridge 200 is titled such that the aperture 205 is facing downwards, the lysis buffer 104 fills the space around the outside of the cavity wall 211, but does not enter the sample receiving cavity 210 because the opening into the sample receiving cavity 210 (adjacent to the swab support 212) is positioned sufficiently high, thereby preventing spilling of the lysis buffer 104 out of the cartridge 200. One or more magnets 105 or electromagnets (or more generally, any suitable magnetic force) can be used to transport magnetic beads 102 from the lysis buffer 104 to the elution buffer 108 via the wash buffer 106 (and via intermediate sections of oil 112). However, viscous material such as mucous may be present on the swab tip, and the magnetic beads 102 can become stuck to such viscous material, preventing or inhibiting the beads from being transported further along the device 200 towards the elution buffer 108 by the magnet 105. If the swab tip were to contact the base 214 of the chamber 309 the mucous may be transferred, increasing the likelihood that the beads 102 will encounter the mucous and become stuck. Advantageously, the cavity wall 211 and the swab support 212 prevent the swab from being pushed against the base 214 of the chamber 309 by a user, reducing the risk of mucous or other viscous material being transferred. As will be described in more detail later with reference to Figs. 22a and 22b, the level of the lysis buffer 104 is advantageously below the level of the swab support 212 when the device 200 is in a generally horizontal orientation (as illustrated in Fig. 3). Beneficially, therefore, the beads 102 can be transported along the length of the device 200 using the magnet 105 when the device 200 is in the generally horizontal orientation and the level of the lysis buffer 104 is below that of the swab support 212 (and therefore not covering the tip of the swab), reducing the risk that beads 102 will encounter the swab tip and become stuck to mucous or other viscous material. The swab tip need not necessarily remain inside the device 200, and could be removed before the device 200 is moved into the generally horizontal orientation. In this case, the configuration of the device 200 is nevertheless advantageous since by virtue of the level of the lysis buffer 104 being below that of the swab support 212, the risk of beads 102 encountering mucous or other viscous material that was transferred to the swab support 212 from the swab tip is reduced. When the sample is introduced into the device 200 using a swab, a reagent that promotes binding (for example, isopropanol), may be withheld from the first cavity 309 until the swab is sufficiently mixed in the first liquid 104. This is because if the chemical binding forces are too strong, the targeted molecules will be encouraged to bind to the high surface area of the swab itself, rather than to the beads 102. Therefore, the method may comprise mixing the swab tip with the first liquid 104 in the chamber 309, either removing the swab entirely or breaking off the swab tip, and then adding a binding promoting agent into the first cavity 309. At this stage, if the swab tip remains inside the device 200, it is further beneficial that the liquid level is below that of the swab support 212 and swab tip when the device is in the generally horizontal orientation, to prevent yet uncaptured target molecules from preferentially binding to the swab instead of to the beads 102. One or more reagents or components (e.g. isopropanol, or the beads) may be introduced into the first cavity 309 using a blister pack. The blister pack may be arranged over the opening 205 into the first cavity 309. In use, a user may pop or rupture the blister pack to deliver the reagents or components into the first cavity 309. The blister pack may then be peeled off from the opening 205 to allow the sample to be introduced into the first cavity 309. Alternatively, the blister pack may be arranged at any other suitable position, to deliver the reagents or components into the first cavity. The second portion 204 of the cartridge 200 comprises a first rotating valve 216 and a second rotating valve 218. Each of the rotating valves 216, 218 comprises a respective cavity 300, 301 that is filled with oil 112. In use, when the first rotating valve 216 is in an open position in which the cavity 300 of the first rotating valve 216 that contains the oil 112 is generally aligned with an opening into the cavity 309 that contains the lysis buffer 104, and is generally aligned with a cavity 303 that contains the wash liquid 106, the magnetic beads 102 can be transported from the lysis buffer 104 in the first portion 202 and into the oil 112 inside the first rotating valve 216 using the magnet 105. The beads 102 can then be transported from the oil 112 inside the first rotating valve 216 into the cavity 303 that contains the wash liquid 106. The cross-sectional area of the liquid-liquid interface between the lysis buffer 104 and the oil 112 is relatively small (and similarly the cross-sectional area of the liquid-liquid interface between the oil 112 and the wash buffer 106 is relatively small), which improves the separation of the two liquids via the surface tension between the immiscible liquids. The cavity 303 that contains the wash liquid 106 is arranged between the two rotating valves 216, 218, as illustrated in Fig. 3. When the second rotating valve 218 is in an open position (in which the cavity 301 of the second rotating valve 218 that contains the oil 112 is aligned with an opening into the cavity 303 that contains the wash liquid 106, and is aligned with an opening into the cavity 305 that contains the elution buffer 108), the beads can be transported from the wash liquid 106 and into the elution buffer 108, via the oil 112 in the second rotating valve 218, using the magnet 105. It will be appreciated, therefore, that when the rotating valves 216, 218 are in the open position the beads 102 can be transported along the length of the device 200 to pass through the sequence of liquids (e.g. as illustrated schematically in Figs. 1a). It will also be appreciated that when the rotating valves 216, 218 are in the open position, the cavities 300, 301 that contain the oil 112 need not necessarily be perfectly aligned with the cavities that contain the other liquids. For example, there may be a partial overlap between the openings into the cavities, through which the beads 102 can nevertheless still be transported. Each of the rotating valves 216, 218 is arranged in a respective cavity in the second portion 204 having a corresponding cavity wall 222, 224. A set of O-rings 220 are provided to form seals between the outer surface of the rotating valves 216, 218 and the cavity walls 222, 224. A pair of angled O-rings 220a, 220b (see also Fig. 19, for example) are provided adjacent to the first rotating valve 216, and a further pair of angled O-rings 220d, 220e are provided adjacent to the second rotating valve 218. A first of the angled O-rings 220a is provided at the interface between the chamber 309 that contains the lysis buffer 104 and the first rotating valve 216. A second of the angled O-rings 220b is provided at the interface between the first rotating valve 216 and the chamber 303 that contains the wash buffer 106. A third of the angled O-rings 220d is provided at the interface between the chamber 303 that contains the wash buffer 106 and the second rotating valve 218. A fourth of the angled O-rings 220e is provided at the interface between the second rotating valve 218 and the chamber 305 that contains the elution buffer 108. When the rotating valves 216, 218 are in the closed configuration, the openings of the cavities of the rotating valves 216, 218 that contains the oil 112 are not aligned with the openings of the cavities that contain the other liquids. In other words, a barrier is formed such that there is no interface between the liquid in the cavity inside the rotating valves and the other liquids. The outer surface of the rotating valves 216, 218 pushes against the angled O-rings 220 to form the sequence of barriers. For example, a surface of the first rotating valve 216 pushes against the second angled O-ring 220b, and a surface of the second rotating valve 218 pushes against the third angled O-ring 220d, thereby sealing the wash liquid 106 inside the corresponding cavity 303 when the rotating valves 216, 218 are in the closed configuration. Advantageously, therefore, the provision of the angled O-rings 220 and the barriers that are formed between the liquids help to prevent the liquids in the cartridge 200 from mixing (e.g. due to vibrations during transport of the device 200) when the rotating valves 216, 218 are in the closed position, and also help to prevent the liquids from leaking from the cartridge 200. Generally horizontal O-rings 220c, 200f are also provided around each rotating valve 216, 218, above the angled O-rings 220. These O-rings 220c, 200f provide additional protection against liquids leaking from the cartridge 200 by preventing the oil 112 from leaking from the space around the rotating valves 216, 218. These O-rings 220c, 220f also act as a bearing surface for the valves 216, 218 to rotate against, and circumferentially support each rotating valve 216, 218 during rotation. The rotating valves 216, 218 thus only make contact with the three O-rings in each cavity (the two angled O-rings 220a, 220b, 220d, 220e and the generally horizontal O-ring 220c, 220f). The cavities in which the rotating valves 216, 218 are situated each have only three openings, each gasketed with an O-ring, and allowing the valve 216, 218 itself to seal off that portion of the device 200 (by engaging with the three O-rings). Advantageously, in addition to the oil 112 provided inside the rotating valves 216, 218, that forms part of the path for the beads 102 to travel from the lysis buffer 104 to the elution buffer 108, additional oil 112 is also provided between the rotating valves 216, 218 and the cavity walls 222, 224 of the cavities in which the rotating valves 216, 218 are situated. Beneficially, therefore, even if some of the liquid (e.g. the lysis buffer 104) breaches an O-ring 220 seal, the oil 112 between the rotating valves 216, 218 and the cavity walls 222, 224 helps to prevent the liquid from progressing further along the cartridge 200, or from leaking out of the cartridge 200. The oil 112 between the rotating valves 216, 218 and the cavity walls 222, 224 also helps to provide lubrication to aid in the rotation of the valves 216, 218, and reduces the risk of air bubbles becoming trapped when filling the apparatus with oil (since a gap around the rotating valves, even if small, results in the trapping of air inside the apparatus). The generally horizontal O-rings 220c, 220f help to prevent the oil 112 that is between the rotating valves 216, 218 and the cavity walls 222, 224 of the cavities in which the rotating valves 216, 218 are situated from leaking from the device 200. The generally horizontal O-rings 220c, 200f also aid in centring the rotating valves 216, 218 within the respective cavities, to maintain a more even gap (between the rotating valves 216, 218 and the cavity walls 222, 224) for the oil 112. As shown in Fig. 3, the angled O-rings 220 are angled with respect to the direction of gravity when the device is in a horizontal orientation (and are angled with respect to the orientation of the path for transport of the beads 102 through the rotating valves 216, 218, and through the wash liquid 106). The outer surface of each rotating valve 216, 218 exerts a force on the angled O-rings 220, improving the strength of the seals. Advantageously, by virtue of the angled orientation of the angled O-rings 220, the force from the rotating valves 216, 218 pushing against the angled O-rings 220 has a horizontal component (along the longitudinal direction of the device 200), further improving the strength of the seals, and enabling the strength of the seals to be configurable based on an amount of downward force applied to the rotating valves 216, 218. In the present examples the angled O-rings 220 are arranged at an angle of approximately 45 degrees, as illustrated in Fig. 3. However, it will be appreciated that any other suitable angle could be used (for example, an angle between 20 degrees and 70 degrees, e.g. 30 degrees or 50 degrees). It will also be appreciated that in the present example each angled O-ring 220 opposes the other in its pair in a symmetrical manner, i.e. at mirroring angles (although this need not necessarily be the case). Whilst in the present examples angled O-rings 220 are used to improve the seals between the chambers that contain the rotating valves 216, 218 and the other chambers, this need not necessarily be the case. For example, only the generally horizontal O-rings 220c, 220f may be provided. Alternatively, no O-rings may be provided, and the seals may be achieved, for example, using regions of overmolded gasket material formed using an injection moulding method. The overmolded regions could form part of the main body of the cartridge 200, or could be part of the rotating valves 216, 218. Each of the rotating valves 216, 218 is provided with a respective groove 230, 232 in an upper surface of the valve. The valves 216, 218 can be moved between the open and closed configurations by inserting a rotatable member (e.g. a motor-driven or manually-driven rotatable tab) into the grooves 230, 232, and rotating the members to rotate the valves 216, 218 between the open and closed configurations. The first rotating valve 216 and the second rotating valve 218 may be rotated simultaneously, but could alternatively be rotated sequentially (with either the first rotating valve 216 or the second rotating valve 218 being rotated before the other rotating valve). Whilst in the present example each of the rotating valves 216, 218 is provided with a respective groove 230, 232, this need not necessarily be the case. Alternatively, for example, a hex key could be used to rotate the valves 216, 218, by engaging with a corresponding recess provided on the upper surface of each valve 216, 218. It will be appreciated that the valves 216, 218 could also be rotated in any other suitable manner. When the rotating valves 216, 218 are in the open position, the grooves 230, 232 are arranged generally perpendicularly to the longitudinal direction of the cartridge 200 as shown in Figs. 4a and 4b (the grooves are arranged generally perpendicularly to the path of the magnetic beads 102 along the length of the cartridge 200). When the rotating valves 216, 218 are in the closed position, the grooves 230, 232 are rotated by 90 degrees to be generally aligned with the longitudinal direction of the cartridge 200. Advantageously, by virtue of the grooves 230, 232 being aligned with the longitudinal direction of the cartridge 200 when the rotating valves 216, 218 are in the closed position, when the cartridge 200 is inserted into a device for rotating the valves 216, 218 a member or tab of the device can slot into the grooves 230, 232 as the cartridge 200 is inserted into the device. The device for rotating the valves 216, 218 may be the same device that moves a magnet (or otherwise uses a magnetic force) to drive the beads 102 along the length of the cartridge 200. An additional groove 229 is provided adjacent to the second rotating valve 218, and a further groove 228 is provided between the first rotating valve 216 and the second rotating valve 218, to enable a first member or tab to pass along the length of the device 200 and into the groove 230 of the first rotating valve 216, and to allow a second member or tab to pass into the groove 232 of the second rotating valve 216, as the cartridge 200 is inserted. In a particularly advantageous example, the cartridge 200 is configured for insertion into a device that rotates the rotating valves 216, 218, and moves the magnet 105 along the length of the cartridge 200 to transport the beads 102 from the lysis buffer 104 and into the elution buffer 108 (via the wash buffer 106 and the regions of oil 112) after the valves 216,218 have been opened. The configuration of the cartridge 200 therefore enables the process of opening the valves 216, 218 and transporting the beads 102 to be automated, and reduces the risk of user error in the operation of the valves 216, 218. Whilst in the present examples the rotating valves 216, 218 rotate by 90 degrees between the open and closed positions, this need not necessarily be the case. Alternatively, for example, the angular difference between the open and closed positions may be 45 degrees, or any other suitable angle. In the present examples, the ratio of the diameter (and similarly, the radius and cross-sectional area) of the chambers 300, 301 inside the rotating valves 216, 218 that contain the oil 112 to the longitudinal length of the chambers 300, 301 (related to the ‘aspect ratio’ of the chambers 300, 301) is relatively small. Similarly, the cross-sectional area of the cavity 309 that contains the lysis buffer 104 at the interface with the oil 112 is relatively small, the cross sectional areas of the cavity 303 that contains the wash buffer 107 at the interfaces with the oil 112 is relatively small, and the cross section area of the cavity 305 that contains the elution buffer 108 at the interface with the oil 112 is relatively small. Advantageously, this reduces the propensity for the oil 112 to mix with neighbouring liquids (the lysis buffer 104, wash buffer 106 and elution buffer 106) when the valves 216, 218 are in the open configuration. However, depending on the immiscibility of the particular liquids used, this need not necessarily be the case. Fill ports are also provided within the recesses 230, 232, for filling the wash buffer 106 in the cartridge 200. A method of injecting wash buffer 106 into the cartridge will be described in more detail later with reference to Fig. 27. Whilst in the present example the rotating valves 216, 218 can be rotated by inserting members or tabs into the corresponding grooves 230, 232, this need not necessarily be the case. Alternatively, for example, upwardly extending tabs may be provided on the upper surface of the rotating valves 216, 218. The tabs could then be gripped and rotated by a user (or by a mechanical device) to rotate the valves 216, 218 between the open and closed configurations. However, the use of grooves 230, 232 is particularly advantageous since they reduce the risk of the valves 216, 218 being inadvertently rotated. The volume of oil 112 provided inside the corresponding cavity 300, 301 of each rotating valve 216, 218 may be, for example, between approximately 50 pl and 150 pl (e.g. 100 pl). The first compartment may contain, for example, between 0.5 ml and 2.5 ml of lysis buffer 104 (e.g. 1 ml of lysis buffer). The capacity of the chamber that contains the lysis buffer 104 may be, for example, between 3 ml and 6 ml. The volume of wash buffer in the cartridge 200 in the chamber 303 between the rotating valves 216, 218 may be, for example, between 25 pl and 150 pl (e.g. 50 pl). As will be described later with reference to Fig. 27, the cartridge 200 may also contain additional wash buffer 106 inside conduits that are used to fill the wash buffer 106 into the chamber 303 between the rotating valves 216, 218. The amount of elution buffer 108 inside the corresponding chamber 305 of the cartridge 200 may be, for example, between 50 pl and 150 pl (e.g. 110 pl). However, it will be appreciated that any other suitable amounts of the liquids could be used, and that the amounts of each liquid may depend on the particular reaction and reagents used. For example, some methods may use a smaller volume of elution buffer 108 in order to obtain a more concentrated eluted sample (or a larger volume of elution buffer 108 to obtain a more dilute eluted sample). Whilst in the present examples, a magnet 105 is used to transport material from the sample along the length of the cartridge 200, this need not necessarily be the case. For example, the beads 102 could simply fall through the liquids by rotating the valves 216, 218 into the open configuration and rotating the cartridge 200 into a vertical configuration (so that the path for the beads 102 through the liquids is generally aligned with the gravitational force). However, use of a magnet 105 enables the beads 102 to be more reliably and efficiently driven through the liquids, potentially in an automated manner. In particular, use of the magnet 105 enables the beads 102 to be driven through the interfaces between the different liquids, at which there may be significant surface tension (due to the use of immiscible liquids to prevent mixing) that inhibits the movement of the beads 102. Moreover, whilst in the present example a magnet 105 may be moved longitudinally along the length of the cartridge 200 to drive the beads 102 through the liquids, the magnet 105 could alternatively, for example, be a fixed magnet 105 positioned adjacent to the part of the cartridge 200 that contains the elution buffer 108, and may simply pull the beads along the cartridge 200 towards the fixed magnet 105. In the example shown in Figs. 3 to 4b the cartridge 200 is provided with a door 206 used to seal the first part 202 of the cartridge 200. Fig. 5 shows a modified cartridge 200’ in which a swab may screw into the first portion 202 of the cartridge 200’. The screw fitting of the swab helps to seal the cartridge 200’ and reduce the risk of leaks or contamination. As shown in Fig. 5, a swab 240 can be screwed into the first portion 202 of the cartridge 200’. In this example the lysis buffer 104 covers the tip 242 of the swab 240 when the device 200’ is in the generally horizonal orientation, but this need not necessarily be the case (alternatively, the lysis buffer 104 may cover the swab tip 242 only when the device 200’ is in a generally vertical orientation, as described above). The opening into the cartridge 200’ comprises a female threaded portion 249 into which a male threaded portion 248 of the swab 240 can be screwed, to seal the chamber using a corresponding cap 246 of the swab 240. Whilst in the example shown in Fig. 5 the swab support 212 is not provided, and the base 250 of the chamber that contains the lysis buffer 104 has a flat and sloping configuration, this need not necessarily be the case. Alternatively the first portion 202 of the cartridge may be as illustrated in the example shown in Fig. 3, but having the door 206 replaced with the female threaded region 249 of Fig. 5 for received the threaded swab 240 (although the door 206 could additionally be provided, to seal the opening into cartridge 200’ whilst the swab is in use for collecting a sample). In the example of Fig. 5 the conduits 323-326 used to fill the cartridge with oil 112 and wash buffer 106 have also been modified, but it will be appreciated that any suitable arrangement of fill conduits could be used. However, a particularly advantageous configuration for the fill conduits and corresponding methods will be described in more detail later. In the example of Fig. 5, dowel pins 221a, 221b are also provided, for retaining the rotating valves within the cartridge 200. Returning now to the cartridge 200 illustrated in Figs. 3 to 4b, Fig. 6 shows a further perspective view of the cartridge 200. As shown in the figure, an aperture 307 is provided to enable the elution buffer 108 to be extracted from the cartridge 200 for subsequent analysis or testing (or to be moved to another region of the cartridge 200 not shown in the figures). The aperture 307 could, for example, be provided with a removable cap that can be opened to provide access to the chamber that contains the elution buffer 108 and the eluted species from the sample. Alternatively, for example, the aperture 307 could be covered with a foil seal that could be punctured or removed to extract the elution buffer 108. The aperture 307 could alternatively be provided with means for attaching to a syringe tip (e.g. a luer-lock fitting) for extraction of the elution buffer using a syringe. A plunger 318 that can be used to extract the elution buffer 108 will be described in more detail later with reference to Figs. 29 and 30. Fill ports used to fill the oil 112 and wash buffer (wash liquid) 106 into the corresponding cavities of the cartridge 200 will now be described, with reference to Figs. 7 to 11. The filling process will be described in more detail later with reference to Figs. 23 to 32. Fig. 7 shows a top-down view of the cartridge 200. As shown in the figure the first rotating valve 216 comprises a first wash liquid fill port cover 226, and the second rotating valve 218 comprises a second wash liquid fill port cover 227. The first wash liquid fill port cover 226 is shown in an open position, in which an opening 262 into the cartridge for filling the wash liquid is exposed via an opening in the cover 226. The second wash liquid fill port cover 226 is illustrated in a closed position in which an opening 262 into the cartridge for filling the wash liquid 106 is covered by the fill port cover 227. O-rings 298 (see e.g. Figs. 15, 16 and 19) are provided at the openings, and the wash liquid fill port covers 226, 227 engage with the O-rings 298 when in the closed position to seal the wash liquid within the cartridge 200. Each of the wash liquid fill port covers 226, 227 is moveable between the open and closed positions by sliding the fill port cover 226, 227 within a corresponding groove provided on the upper surface of the rotating valves. Also shown in Fig. 7 are two recesses 266a, 226b provided adjacently to the first rotating valve 216, and two recesses 268a, 268b provided adjacently to the second rotating valve 218. As will be described in more detail later with reference to Figs. 16 to 18, these recesses are associated with corresponding tabs (or ‘fins’) provided on the rotating valves 216, 218, and enable the rotating valves 216, 218 to be inserted into the respective cavities of the cartridge 200 when assembling the device. Whilst in the examples illustrated in Figs. 7 to 11 the wash buffer is filled via corresponding fill ports provided on the upper surface of the rotating valves, this need not necessarily by the case. Alternatively, for example, the wash buffer region could be filled with the wash buffer via ports provided in the main body of the cartridge, or via any other suitable opening. Fig. 8 shows a view of a side of the cartridge from which oil is filled. A first pair of oil fill ports 270, 272 are provided for filling the oil chamber 300 of the first rotating valve 216 with oil 112 (and for filling the space between the first rotating valve 216 and the cavity walls 222 with oil 112). A second pair of oil fill ports 274, 276 are provided for filling the oil chamber 301 of the second rotating valve 218 with oil 112 (and for filling the space between the second rotating valve 218 and the cavity walls 222 with oil 112). A first oil fill port cover 278 and a second oil fill port cover 280 are provided for the first rotating valve 216 and the second rotating valve 218, respectively. The oil fill port covers 278, 280 are shown in the open position (or ‘filling position') in Fig. 8, in which the oil fill ports are accessible via corresponding openings in the oil fill port covers 278, 280. The oil fill port covers 278, 280 can be moved into a closed position by sliding (towards the left-hand side of Fig. 8) the covers 278, 280 within corresponding recesses 282, 284 such that the openings in the fill port covers 278, 280 are no longer aligned with the oil fill ports, and the oil fill ports are sealed closed by the fill port covers. The first oil fill port cover 278 is provided with a pair of alignment points 265a, 265b that help to maintain alignment of the fill port cover 278 with the cartridge 200. The second oil fill port cover 280 is also provided with a corresponding pair of alignment points 265a, 265b. The alignment points 265, 267 may also be used for sliding the oil fill port covers 278, 280 between the open and closed positions. As shown in Fig. 8, the opening in the oil fill port cover 278, 280 that provides access to one of the oil fill ports 270, 274 (in this example, the lower oil fill port) is circular, whereas the opening in the oil fill port cover 278, 280 that provides access to the other oil fill port 272, 276 has an elongate shape (in this example, an oval). Advantageously, the combination of the circular opening and the elongate opening means that when the fill port cover 278, 280 is slid into the closed position, one of the oil fill ports 270 will be sealed closed before the other oil fill port 272 is sealed closed. When the oil fill port cover 278, 280 is slid into the closed position, an increase in the fluid pressure of the oi! 112 can occur. This can increase the risk of the liquids inside the cartridge 200 mixing or leaking, or result in liquid being ejected into the cavity 309 that contains the lysis buffer 104 (since the cavity 309 that contains the lysis buffer 104 is only partially filled with lysis buffer 104 and therefore acts as a compressible volume). Advantageously, by virtue of the fill port covers 278, 280 sealing one of the oil fill ports before the other oil fill port, as the oil fill ports are closed, excess pressure build-up in the oil 112 is beneficially avoided, since the excess pressure is released via the fill port that is seated last (the fill port that is accessed via the asymmetrical or elongate opening in the oil fill port cover plate 278, 280). Whilst in the example illustrated in Fig. 8 the fill port covers 278, 280 are provided with a circular opening and an elongate opening to access the oil fill ports, any other suitable shapes for the openings that results in either the upper or lower fill port being sealed closed before the other of the fill ports could be used (e.g. a square opening and a rectangular opening). Moreover, whilst the configuration of the openings in the fill port covers 278, 280 illustrated in Fig. 8 that result in a staggered closing of the fill ports is particularly advantageous, staggered closing of the fill ports need not necessarily be used. Fig. 9 shows a view of the underside of the cartridge 200, in which the recesses 282, 284 into which the oil fill port covers 278, 280 can be slid into to seal the oil fill ports can be seen. Figs. 10 and 11 show cutaway views of the cartridge 200, showing the oil fill port cover 278 and the conduits 286, 288 via which the cartridge 200 is filled with oil 112. As shown in the figures, the oil fill port cover 278 is provided within a corresponding casing 296, within which the oil fill port cover 278 can be slid between the open and closed positions. As shown in Fig. 11, there is space provided within the casing 296 for the oil fill port covers 278 to slide (towards the left hand side of Fig. 11) into the closed position, to seal closed the oil fill ports. Each of the oil fill ports is coupled to a corresponding conduit 286, 288 that leads to the cavity in which the rotating valve 216 is situated. As will be described in more detail later, oil 112 is filled into the cartridge 200 via one of the oil fill ports and the corresponding conduit, and exits via the other conduit and the corresponding oil fill port. This method of filling the oil 112 beneficially reduces the occurrence of air bubbles forming inside the oil 112, which would inhibit the transport of the beads 102 through the oil 112 using the magnet 105. O-rings (not visible in Figs. 10 or 11) are provided at the oil fill ports, inside a corresponding O-ring casing 292. As the oil fill port cover 278, 280 is slid into the closed position, the cover 278, 280 engages with the O-rings to seal the oil fill ports closed. Whilst in the examples illustrated in Figs. 7 to 11 sliding fill port covers and corresponding O-rings are used to close and seal and fill ports, this need not necessarily be the case. Alternatively, each of the fill ports could be closed and sealed using any other suitable means. For example, the fill ports could be closed using an adhesive or heat-seal foil, using a rubber stopper or plug, using a UV cure adhesive, using an ultrasonically welded plug or cap, or using a press-fit plastic plug. In a further alternative the fill ports could be closed using a bolt, screw or threaded cap, where each fill port is threaded for receiving the bolt or screw to seal the fill port closed. Figs. 12 to 15 show further cross-sectional and cutaway views of the cartridge 200, in which the tapered shape of the cavity 309 that contains the lysis buffer 104 can be seen. As illustrated in Fig. 12, the width of the cavity 309 decreases, in the transverse direction, along the longitudinal length of the cartridge 200 towards the second portion 204 of the cartridge 200. As illustrated in Fig. 13, the height of the cavity 309 also decreases towards the second portion 204 of the cartridge. As will be described in more detail later with reference to Figs. 22a and 22b, by virtue of the tapered shape of the cavity 309 that contains the lysis buffer 104, the level of the lysis buffer 104 is advantageously below the level of the swab support 212 when the cartridge 200 is in a generally horizontal orientation, but covers the swab tip 312 when the cartridge 200 is in a generally vertical orientation. Fig. 16 shows a top-down cutaway view of the cartridge 200 in which the tabs 279a, 279b of the first rotating valve 216 and the tabs 285a, 285b of the second rotating valve 218 can be seen. The rotating valves 216, 218 are illustrated in the open configuration in Fig. 16, in which the beads 192 can be moved along the length of the cartridge 200 from the lysis buffer 104 to the elution buffer 108. The tabs 279, 285 engage with the main body of the second portion 204 of the cartridge 200, exerting a generally downward force on the rotating valves 216, 218. This force pushes each rotating valve 216, 218 against the respective angled O-rings 220 (and against the generally horizontal O-rings 220c, 220f), improving the strength of the seals. In order to move the rotating valves 216, 218 into the open configuration, the rotating valves 216, 218 are rotated by 90 degrees in a counterclockwise direction (when the cartridge is viewed top-down as in Fig. 16). The tabs 285, 279 remain engaged with the main body of the second portion 204 of the cartridge 200 when the rotating valves 216, 218 are in the closed configuration (rather than the tabs 279, 285 being aligned with the recesses 266, 268 provided adjacently to each rotating valve 216, 218). The recesses 266, 268 adjacent to each rotating valve 216, 218 are provided so that the tabs 279, 285 can pass through the recesses during assembly, to enable the rotating valves 216, 218 to be inserted into the cartridge 200 during manufacture. However, it will be appreciated that these recesses 266, 268 need not necessarily be provided. For example, the rotating valves 216, 218 could be placed inside the cartridge 200 before the uppermost parts of the cartridge 200 are assembled. Whilst the rotating valves 216, 218 of the present example are provided with tabs (or ‘fins’) for engaging with the main body of the cartridge 200 to push the rotating valves 216, 218 against the angled O-rings, it will be appreciated that these members need not necessarily be tab or fin shaped. Any other suitable member for engaging with the main body of the cartridge 200 to push the rotating valves 216, 218 against the O-rings 220 could alternatively be used. Alternatively, for example, an arrangement of springs could be used to push the rotating valves 216, 218 against the angled O-rings to improve the strength of the seals. In a further alternative a c-clip, spring pins or dowel pins could be used to push the rotating valves 216, 218 against the angled O-rings Fig. 19 shows a cutaway and exploded view of the cartridge 200, showing some of the components of the cartridge 200 in more detail. In particular, the O-rings 270, 272 that are arranged between the oil fill plate 278 and the oil fill conduits 286, 288 are shown. The O-ring 298 that is provided between the wash liquid fill port and the wash liquid fill port cover 226 is also shown. The cavity 302 inside which the first rotating valve 216 is arranged can also be seen. As shown in Fig. 19, regions of the wall of the cavity 302 are shaped for receiving the corresponding O-rings. Fig. 20 shows a cutaway view of the cartridge. The arrangement of the swab support 212 above the tapered part of the chamber 309 that contains the lysis buffer 104 can be seen. The slot 213 in the swab support 212 can also be seen in Fig. 20. The slot 213 helps to allow the lysis buffer to flow around the swab tip when the device 200 is in the generally vertical orientation, and to drain back into the cavity 309 when the device 200 is in the generally horizontal orientation. The slot 213 beneficially helps to prevent pooling of the lysis buffer on the swab support 212. In Fig. 20 the upper surface of the first rotating valve 216 has been hidden to illustrate the location of the oil fill conduits 286, 288 and the O-rings. Movement of the beads 102 within the lysis buffer 104 will now be described with reference to Figs. 21a and 21b. Fig. 21a shows an example in which a rotating magnet 306 is used to drive the magnetic beads 102 along the length of the cartridge 200. As the magnet 306 moves along the length of the cartridge 200, the magnet 306 exerts a force on the magnetic beads 102, causing them to move through the lysis buffer 104. The combination of the rotational and translational movement of the magnet 306 results in the beads 102 moving through the liquid in a cloud-like manner. The translational movement of the magnet enables bulk movement of the beads in their dispersed state, as translational movement along the cartridge 200. The rotational movement of the magnet 306 creates an oscillating magnetic field that results in dispersion of the beads within a localized area in all directions, and also assists in the translational movement along the cartridge 200. Beneficially, movement of the beads through the liquid in a cloud-like manner increases the mixing of the beads 102 in the lysis buffer, and reduces the downward component of force on the beads and the corresponding frictional forces (and reduces the risk of beads being dragged along the floor of the cartridge and becoming trapped by discontinuities in the surface). Moreover, the cloud-like formation of the beads enables the use of smaller cross-sectional areas along the path for the beads from the lysis buffer 104 to the elution buffer 108. This is because clumped beads require a larger cross-sectional area for the path, for reliable transportation along the cartridge 200. Advantageously, the use of smaller cross-sectional areas at the liquid-liquid interfaces helps to maintain separation of the liquids. The movement of the beads in the cloud-like manner also occurs as the beads are moved through the other liquids, such as the wash buffer 106 and the elution buffer 108. Whilst one or more non-rotating magnets could alternatively be moved along the length of the cartridge 200 to drive the beads 102 along the cartridge 200, this may result in the beads clumping and dragging along the base 214 of the chamber, decreasing the mixing and exposed surface area of the beads 102 in the lysis buffer 104 and in the elution buffer 108. For the case of the beads moving through the wash buffer 106, clumping of the beads can result in lysis liquid being trapped between the beads and making its way into the elution chamber. In the example shown in Fig. 21a, the base 214 of the chamber 309 comprises a series of ridges or steps (or ‘ribs’, or ‘waves’), which beneficially further increases the mixing of the beads 102 with the lysis buffer 104. As the beads 102 are driven along the length of the chamber 309, the ridges of the base 214 of the chamber 309 result in the beads 102 being pushed upwards away from the base 214, and result in the beads 102 moving turbulently in the lysis buffer 104 as they are transported along the length of the chamber 309, as illustrated schematically by the curly arrow. Therefore, by virtue of the ridged base 214, mixing of the beads in the lysis buffer 104 is improved, reducing the amount of clumping and increasing the surface area of the beads 102 exposed to the lysis buffer 104. Notably, in this example, the upward slope of the ridges (that causes the beads 102 to be pushed upwards to mix with the lysis buffer 102) is angled, rather than being exactly vertical, reducing the risk of beads 102 becoming stuck against the ridges when being driven along the chamber 309 by the magnet 306. As illustrated in Fig. 21a, the amount of lysis buffer 104 inside the chamber 309 is selected so that the level of the lysis buffer 104 (and therefore the maximum height reachable by the magnetic beads 102 in the lysis buffer 104) does not extend past the swab support 212 when the device is in the generally horizontal orientation, reducing the risk of the beads encountering mucous or other viscous material that has been transferred to the swab support 212 from the swab. Whilst the provision of the ridges improves the mixing of the beads 102 with the lysis buffer 104, the base of the chamber 309 need not necessarily be provided with the series of ridges. For example, Fig. 21b shows a modified version of the cartridge 200 in which the chamber 309 is provided with a flat base 308. The liquid level of the lysis buffer 104 when the cartridge 200 is in the generally vertical and horizontal orientations will now be described with reference to Figs. 22a and 22b. Fig. 22a shows the cartridge 200 in a generally vertical orientation. In the example shown in Fig. 22a, the cartridge 200 is held by a user who has inserted a swab into the cartridge 200. By virtue of the tapered shape of the chamber 309 that contains the lysis buffer 104, the lysis buffer 104 covers the tip 312 of the swab 310 when the cartridge 200 is in the generally vertical orientation, enabling the lysis buffer 104 to cause species from the sample to be released into the liquid. The swab support 212 may be provided with ribbing or dimpling, or any other suitable texture, to aid in the mechanical removal of material from the swab tip after it is inserted into the cartridge 200. A wall of the cavity 309 may also comprise a textured region to aid in the mechanical removal of material from the swab tip. Fig. 22b shows a view of the cartridge 200 after the cartridge 200 has been rotated into the generally horizontal orientation. By virtue of the tapered shape of the chamber 309 that contains the lysis buffer 104, the lysis buffer 104 does not cover the tip 312 of the swab 310 when the cartridge 200 is in the horizontal orientation (as described above, the tip of the swab engages with the swab support 212, and the level of the lysis buffer 104 is below the level of the swab support 212). The magnet 105 can then be moved along the length of the chamber 309 when the cartridge 200 is in the horizontal orientation, in order to mix the beads in the lysis buffer 104. Advantageously, since the lysis buffer 104 does not cover the swab tip 312 in Fig. 22b, the risk of the beads 102 becoming stuck to mucous or other viscous material on the swab tip 312 as the beads 102 are driven through the liquid by the magnet 105 is beneficially reduced. Moreover, as a result of the tapered shape of the chamber 309, the depth of the lysis buffer 104 is relatively small when the cartridge 200 is in the horizontal orientation. This relatively low liquid level enables the cloud of beads 102 to more easily be mixed within the full cross-sectional area of the lysis buffer 104, helping to ensure that no target molecules are unreachable. Fig. 23 shows a further exploded cross-sectional view of the cartridge 200 showing the cavity 302 within which the first rotating valve 216 is rotated to transition between the open and closed configurations. Fig. 24 shows a further cross-sectional view of the cartridge 200, showing the arrangement of O-rings 220 and the first rotating valve 216 within the cavity 302 in more detail. As descried above, the first rotating valve 216 pushes against the O-rings 220, improving the strength of the seals inside the cartridge 200, reducing the risk of the liquids mixing or leaking from the cartridge 200. As described above, a chamber 300 inside the first rotating valve 216 is filled with oil 112, and beads 102 pass from the lysis buffer 104 to the wash buffer 106 via that region of oil 112 inside the first rotating valve 216. However, additional oil 112 is provided between the first rotating valve 216 and the wall of the cavity 302 in which the first rotating valve 218 is situated (and oil 112 is similarly provided between the second rotating valve 218 and the wall of the cavity in which the second rotating valve 218 is situated). For example, oil 112 is provided in a gap 314 between the base of the first rotating valve 216 and the base of the cavity 302, and in the regions 316a, 316b between the angled O-rings 220a, 220b and the generally horizontal O-ring 220c, as illustrated in Fig. 24 (and these regions 314, 316a, 316b are fluidically connected to provide a region of oil 112 around the rotating valve 216). Advantageously, the additional layer of oil 112 further reduces the risk of the liquids leaking from the cartridge 200, and also inhibits the other liquids from evaporating from the cartridge 200. The generally horizontal O-ring 220c helps to seal the additional oil 112 within the cavity 302. In addition to the layer of additional oil 112 provided around the rotating valves 216, 218 beneficially reducing the risk of leakage or mixing of the other liquids, the additional oil 112 can also provide lubrication, enabling the rotating valves 216, 218 to be rotated more easily within the cavities 302 (although this need not necessarily be the case, depending on the particular liquid used). It will be appreciated that the liquid provided around each rotating valve 216, 218 need not necessarily be the same as the liquid provided inside the rotating valves 216, 218 (through which the beads 102 pass). Indeed, the substance provided between the rotating valves 216,218 and the wall of the cavities 302 in which the rotating valves 216, 218 are situated need not necessarily be a liquid. For example, a paste (e.g. grease) could be used to fill the gap between the rotating valves 216, 218 and the wall of the cavity 302, reducing the risk of liquids leaking from the cartridge 200. However, use of a liquid (e.g. oil 112) may be preferred, as this can be more easily injected into the cartridge 200. Filling of Liquids Filling of the oil 112 and wash buffer 106 into the cartridge 200 will now be described in more detail, with reference to Figs. 25 to 27. Fig. 25 shows a cross-sectional view of the first rotating valve 216 when the first rotating valve 216 is in the open position. As shown in Fig. 26, when the first rotating valve 216 is in the open position 300, the chamber 300 inside the first rotating valve 216 to be filled with oil 112 is aligned along the longitudinal length of the cartridge 200. The oil fill conduits 286, 288 are therefore not aligned with the chamber 300 inside the first rotating valve 216. The conduit 252 for filling the wash buffer 106 can also be seen. In the example shown in Fig. 25 the wash fill port cover 226 is in the closed position, sealing closed the opening into the wash buffer fill conduit 252 (by engaging with the corresponding O-ring 298). Similarly, the oil fill conduits 286, 288 can be sealed closed by the corresponding oil fill port cover plate 278 (by engaging with the corresponding O-rings 270, 272). Therefore, both the oil fill conduits 286, 288 and the wash buffer fill conduit 252 are sealed closed, and this configuration may be used, for example, after the liquids have been filled into the cartridge, and the beads are to be transported through the liquids. Fig. 26 shows the cross section of Fig. 25, but when the first rotating valve 216 is in the closed configuration. When the first rotating valve 216 is in the closed configuration, the chamber 300 inside the first rotating valve 216 to be filled with oil 112 is arranged along the transverse direction across the cartridge 200. One of the oil fill conduits 286, 288 is partially aligned with the chamber 300 inside the first rotating valve 216 (in this example, the lower oil fill conduit 286 partially overlaps with the opening into the oil chamber 300 inside the rotating valve 216, but alternatively the oil fill conduit 286 could fully overlap with the opening into the oil chamber 300). Therefore, the chamber 300 inside the first rotating valve 216 can be filled with oil 112, via the corresponding oil fill conduits 286, 288, when the first rotating valve 216 is in the closed position. Oil 112 can be injected into the cartridge 200 via the lower oil fill conduit 286 (through the corresponding opening in the oil fill port cover plate 278 when the oil fill port cover plate 278 is in the open position). The oil 112 will then flow through the conduit 286 and into the chamber 300 inside the rotating valve 300. Advantageously, the oil 112 will also flow into the cartridge 200 to fill the space in between the first rotating valve 216 and the wall of the cavity 302 in which the first rotating valve 216 is situated. As described above, this additional oil 112 provided around the outside of the rotating valves 216, 218 beneficially reduces the risk of the liquids inside the cartridge 200 mixing or leaking (and also reduces the amount of evaporation). During the fill process, oil flows out of the cartridge 200 via the upper oil fill conduit 288. In other words, oil flows into the cartridge 200 via the lower fill conduit 286, and out of the cartridge 200 via the upper fill conduit 288. Alternatively, the oil 112 could be injected into the upper oil fill conduit 288 and flow out of the cartridge 200 via the lower oil fill conduit 286, but filling using the lower oil fill conduit 286 as the inlet, i.e. from the bottom up, may be preferable, to reduce the likelihood of air bubbles forming in the oil 112. Advantageously, by virtue of the provision of the two oil fill conduits 286, 288, a flow of oil 112 can be pushed through the corresponding cavities inside the cartridge 200, reducing the risk of air bubbles being formed inside the chamber 300 (or being formed in the space between the first rotating valve 216 and the cavity in which the first rotating valve 216 is situated) inside the first rotating valve 216, which would inhibit movement of the beads 102 along the chamber 300. In contrast, if only one oil fill conduit 286 were used to fill the oil 112, air inside the chamber 300 may become trapped and compressed. Whilst the use of a pair of oil fill conduits 286, 288 is preferred to reduce the risk of the trapping of air bubbles, alternatively one oil fill conduit could nevertheless be used (for example, the strength of the magnet 105 may be such that the magnetic beads 102 can be driven through any air bubbles that form). Whilst in the present example the two oil fill conduits 286, 288 are located on the same side of the cartridge 200, this need not necessarily be the case, and each of the oil fill conduits 286, 288 could alternatively be arranged at any other suitable location on the cartridge 200 (e.g. on opposing sides of the cartridge, such that oil flows into the cartridge 200 in one side, and out of the cartridge 200 on the other side). It will be appreciated the configuration of the cartridge 200 for filling the second rotating valve 218 with oil 112 (via a corresponding second pair of oil fill conduits) is the same as the configuration used for the first rotating valve 216 that has been described above with reference to Figs. 25 and 26. Fig. 27 shows a cross-sectional view of the cartridge 200, illustrating the path through which the wash buffer 106 flows to fill the cartridge 200 with the wash buffer 106. As shown in the figure, the rotating valves 216, 218 are in the closed configuration, and a path is formed from the wash buffer fill port of the first rotating valve 216 to the wash buffer fill port of the second rotating valve 218. The wash buffer fill port covers 226, 227 are in the open positions, in which wash buffer 106 can flow into (and out of) the cartridge 200. In order to fill the wash buffer cavity 303 between the two rotating valves 216, 218 with the wash buffer 106, the wash buffer 106 is injected into the opening in the upper surface of the first rotating valve 216 to flow along the corresponding wash buffer fill conduit 252, along the wash buffer cavity 303, and out of the cartridge 200 via the wash buffer fill conduit 254 provided in the second rotating valve 218. In other words, wash buffer 106 flows into the cartridge 200 via the opening in the first rotating valve 216 and flows out of the cartridge 200 via the opening in the second rotating valve 218 (alternatively the flow direction may be reversed, such that the wash buffer 106 flows into the cartridge 200 via the opening in the upper surface of the second rotating valve 218 and flows out of the cartridge 200 via the opening in the upper surface of the first rotating valve 216). By virtue of the two wash buffer fill conduits 252, 254 forming a path for a flow of the wash buffer 106 into and out of the cartridge 200 during the fill process, the risk of air bubbles forming inside the cavity 303 during the fill process is beneficially reduced. In contrast, if the wash buffer 106 was filled into the wash buffer cavity 303 using a single conduit, the flow of the wash buffer 106 into the cavity would compress the air in the cavity 303, forming an air bubble (which could inhibit the movement of the magnetic beads 102 along the cavity 303). Nevertheless, whilst the use of two wash buffer fill conduits 252, 254 is preferred to reduce the risk of the trapping of air bubbles, one wash buffer fill conduit could alternatively be used. Moreover, whilst in the present example the wash buffer fill conduits 252, 254 are provided inside the rotating valves 216, 218, this need not necessarily be the case. Alternatively, for example, wash buffer fill ports could be provided on the side of the cartridge 200 (e.g. on the same side of the cartridge 200 on which the oil fill ports are provided). However, the present inventors have found that the configuration illustrated in Fig. 27 is particularly advantageous, as the path for flow of the wash buffer 106 into and out of the cartridge 200 during the fill process reduces the risk of air bubbles becoming trapped. In contrast, when the wash buffer cavity 303 is filled from the side of the cartridge, the present inventors have found that air bubbles are more prone to forming near the interfaces between the wash buffer fill conduits 252, 254 and the wash buffer cavity 303, as well as in the regions of the cavity 303 proximal to each of the rotating valves 216 and 218. When the filing of the wash buffer 106 into the wash buffer cavity 303 is complete, the wash buffer fill port covers 226, 228 are moved into the closed position. Wash buffer 106 remains in the wash buffer fill conduits 252, 254 after the filling process is complete. Advantageously, by virtue of the additional oil 112 provided around the outside of the rotating valves 216, 218, the risk of the wash buffer 106 leaking out of the wash buffer fill conduits 252, 254 (e.g. after the rotating valves 216, 218 have been rotated into the open configuration) is beneficially reduced. Fig. 28 shows a further cross-sectional view of the cartridge 200 when the rotating valves are rotated by approximately 45 degrees from the open position. Elution buffer extraction Extraction of the elution buffer 108 from the cartridge 200 (or into a further region of the cartridge 200 not shown in the figures) will now be described, with reference to Figs. 29 and 30. Figs. 29 and 30 show cross-sectional views of the cartridge 200, in which a plunger 318 can be seen. In use, the plunger 318 is pushed into a corresponding plunger cavity 322 that is filled with the elution buffer 108, to push the elution buffer 108 out of the cavity and out of the end of the cartridge 200 via the corresponding aperture 307 (the aperture can be seen in Fig. 6). The elution buffer chamber 305, that is full of elution buffer 108, provides a path from the oil 112 inside the second rotating valve 218 to the elution buffer 108 in the plunger cavity 322. It will be appreciated, therefore, that when the second rotating valve 218 is in the open position, the beads 102 can be transported by the magnet 105 from the oil 112 inside the second rotating valve 218 and into the elution buffer 108 inside the plunger cavity 322. The elution buffer 108 causes the chemical or biological species from the sample to separate (elute) from the beads 102, into the elution buffer 108, ready for extraction from the cartridge 200 (or into a further region of the cartridge 200 not shown in the figures). Advantageously, as illustrated in Fig. 27, the curved walls of the elution buffer chamber 305 encourage mixing of the beads 102 in the elution buffer 108. As shown in the Figure, when a magnet 306 is positioned generally adjacent to the elution buffer chamber 305 and rotated, the beads 102 follow a path generally along the curved walls of the chamber 305 as indicated by the arrow 311, improving the mixing of the beads 102 within the liquid. The beads 102 may be removed from the elution buffer 108 before the elution buffer 108 is extracted. For example, the beads 102 may be transported back to the cavity 309 that contains the lysis buffer 104. The second rotating valve 218 can then be rotated into the closed position (the first rotating valve 216 may also be rotated into the closed position, but this is not necessary for extracting the elution buffer 108). The plunger 318 is then pushed into the corresponding plunger cavity 322, thereby causing the elution buffer 108 to be ejected out of the cavity 305 that contains the elution buffer 108 (e.g. into a further region of the cartridge 200 not shown in the figures, or from the cartridge 200 itself). As shown in Fig. 30, a plunger face 322 of the plunger 318 is shaped to fit against the wall of the cavity 305 that contains the elution buffer 108 when the plunger 318 has been pushed into the cavity, maximising the amount of elution buffer 108 that is ejected. An O-ring 320 is also provided around the plunger 318, to reduce the risk of elution buffer 108 leaking around the edges of the plunger 318 and out of the cartridge 200. The plunger 318 may be pushed into the cartridge 200 to eject the elution buffer 108 by a user manually pushing against the exterior surface 234 of the plunger 318, but could alternatively be pushed using a mechanical device, for example a linear actuator. As shown in Fig. 4b, the exterior surface 234 of the plunger 318 may have an asymmetrical shape, to ensure that the plunger 318 is correctly orientated inside the cartridge 200 during manufacture, so that the plunger face 322 is correctly orientated to fit against the wall of the cavity 305 that contains the elution buffer 108. Advantageously, the exterior surface 234 of the plunger 318 is substantially flush with the outer surface of the device 200, reducing the risk of a user inadvertently depressing the plunger. In a particularly advantageous embodiment, the cartridge 200 is inserted into a device that rotates the rotating valves 216, 218 between the open and closed positions, moves the magnet 105 along the length of the cartridge, and operates the plunger 318. Advantageously, therefore, the process of extracting the chemical or biological species from the sample, moving the beads 102 through the liquids and into the elution buffer 108, moving the beads out of the elution buffer 108, and then extracting the elution buffer 108 can be automated, beneficially reducing the risk of user error in the operation of the valves 216,218, magnet 105 or plunger 318. For example, by virtue of providing a device to control the operation of the plunger 318 and the rotating valves 216, 218, a situation in which a user inadvertently pushes in the plunger whilst the rotating valves 216, 218 are in the open configuration (which may result in the elution buffer 108 being pushed back through the cartridge 200, and ejection of liquid into the chamber that contains the lysis buffer 104) can advantageously be avoided. Similarly, a situation in which the user inadvertently ejects the elution buffer 108 before the magnetic beads 102 have been removed from the elution buffer 108 using the magnet 105 can be avoided. Whilst the use of a plunger 318 provides a particularly efficient method for extracting the elution buffer 108, it will be appreciated that the plunger 318 need not necessarily be provided. Alternatively, for example, the aperture 307 into the cavity 305 that contains the elution buffer 108 could be provided with a foil seal or plug, which could be punctured or opened to allow the elution buffer 108 to drain out of the cavity 305, or for it to be removed with an instrument such as a pipette. Oil Pressure As described above, during the filling of oil 112 into the cartridge 200, the pressure of the oil 112 may increase when the oil fill port cover plates 278, 280 are closed to seal the oil 112 within the cartridge 200. This increase in pressure can disrupt the separation of the oil 112 from the other liquids, and may result in liquid being ejected into the chamber that contains the lysis buffer 104 (when the rotating valves 216, 218 are subsequently rotated into the open configuration). Whilst in the examples described above this effect is mitigated by providing the oil fill port cover plates 278, 280 having an elongated opening into one of the oil fill conduits, Figs. 31a to 31 d show a modified version of the cartridge 200 that further mitigates against the buildup of excess pressure in the oil 112. As illustrated in Figs. 31a and 31b, the cavities in which the rotating valves 216, 218 are situated may be provided with air bubble traps 328 (which may also be referred to ‘gas cavities’ or ‘air cavities’). In the example shown in Figs. 31a and 31b, a plurality of air bubble traps 328 are provided, but alternatively only one air bubble trap 328 could be provided per rotating valve. The air bubble traps 328 are relatively small cavities configured for trapping gas (e.g. air) during the filling process. As the oil fill port cover plates 278, 280 are closed, the increase in pressure causes the air in the air bubble traps 328 to compress, beneficially relieving some of the pressure in the oil 112 (or dampening the spike in the oil pressure that can occur as the oil is sealed inside the cartridge 200). In other words, one or more regions of gas are provided, and the gas compresses when the pressure in the oil 112 increases. Advantageously, the air bubble traps 328 are provided away from the oil cavities 300, 301 inside the rotating valve 216, 218, so that the regions of air do not inhibit the transport of the beads 102 through the oil 112 using the magnet 105. Figs. 31c and 31 d show an alternative in which foam discs 332 are provided in the base of the cavities in which the rotating valves 216, 218 are situated. The foam discs 332 function in a manner similar to that of the air bubble traps 328 described above. As the pressure in the oil 112 increases due to the oil fill port cover plates 278, 280 being closed, the foam discs 332 are compressed, beneficially helping to equalise the pressure in the oil 112 with the pressure of the adjacent liquids. Filling Apparatus Exemplary oil filling apparatus that could be used to inject the oil 112 into the cartridge 200 will now be described with reference to Fig. 32. The filling apparatus may also be referred to as a ‘filling jig’ or ‘oil injector’. As shown in Fig. 32, the filling apparatus can be mounted to the side of the cartridge 200. A first syringe 338 can be used to inject oil 112 into the cartridge 200 via one of the oil fill conduits 286, and oil is pushed out of the cartridge 200 and into a second syringe 340 via the other of the oil fill conduits 288. It will be appreciated that the filling apparatus need not necessarily comprise a syringe, and that any other suitable type of filling apparatus could alternatively be used, for example one or more pumps. Advantageously, by virtue of the provision of the second syringe 340, the oil pressure is increased during the fill process due to the pressure needed to force the oil 112 into the second syringe 340. This temporary increase in pressure (which can be controlled by selecting an appropriately sized second syringe 340) helps to mitigate against the trapping of air bubbles inside the oil 112 during the fill process. Since the rotating valves 216, 218 are in the closed position when the oil is filled 112, the risk of the oil 112 mixing with the other liquids in the cartridge 200 during the temporary increase in oil pressure is reduced. Nevertheless, it will be appreciated that the second syringe 340 need not necessarily be provided. In use, the tips of the syringes may be arranged to engage with the O-rings 270, 272 that are arranged between the oil fill plate 278 and the oil fill conduits 286,288, to provide a particularly good seal with the syringes during the filling process. In a particularly advantageous example, the flow of liquid into the cartridge 200 from the syringe 338 is pulsed, which helps to remove air bubbles from within the liquid inside the cartridge 200. In other words, the flow rate and pressure of the liquid flowing into the cartridge 200 from the syringe 338 is varied during the filling process, which was beneficially found to encourage air bubbles to evacuate the cavity. Whilst the filling apparatus illustrated in Fig. 32 is used for filling the cartridge 200 with oil 112, it will be appreciated that corresponding filling apparatus can be used to fill the cavity that contains the wash liquid 106, as described above with reference to Fig. 27. Method of extracting a chemical or biological species A method of using the cartridge 200 to extract a chemical or biological species from a sample will now be described. In a first step, the rotating valves 216, 218 are initially in the closed orientation, and a user inserts a swab (or alternatively, pipettes a liquid sample) into the aperture 205 of the first portion 202 of the cartridge 200. Any other additional buffers or components (e.g. the beads 102) could also be introduced into the cartridge via the aperture 205 at this stage. The cartridge 200 is in the vertical orientation (as illustrated in Fig. 22a) so that the lysis buffer 104 contacts the tip of the swab (but the cartridge 200 need not necessarily be in the vertical orientation when the swab is inserted). The lysis buffer 104 causes release of DNA, RNA or proteins from the sample, to be bound to the coating of magnetic beads 102 that are in the lysis buffer chamber 309. The swab is then removed from the cartridge 200 by the user, the cap 206 of the device is closed, and the device is rotated into the generally horizontal orientation (as illustrated in Fig. 22b). Alternatively, the swab tip may be broken off and remain inside the cartridge 200 when the cap 206 is closed. In a further alternative, the sample may be introduced into the cartridge 200 using a pipette rather than a swab. In an optional second step, the cartridge 200 is inserted into a machine for rotating the rotating valves 216, 218, moving the magnet 105, and operating the plunger 318. Alternatively, the rotating valves 216,218, magnet 105 and plunger 318 may be operated manually by a user. In a further alternative, when one or more electromagnets are used to manipulate the beads within the cartridge 200, the machine controls the magnetic field generated by the electromagnets, to manipulate the beads within the cartridge 200. More generally, the machine may be used to provide a magnetic field source to manipulate the beads within the cartridge 200. In an optional third step, the magnet 105 is used to move the beads 102 within the lysis buffer 104, to mix the beads with the lysis buffer 104. Advantageously, this increases the amount of the target biological or chemical species that binds to the surface of the beads 102. In a fourth step, the rotating valves 216, 218 are rotated into the open position, thereby removing the barriers between the liquids in the cartridge 200, and forming a path for the beads 102 to be transported from the lysis buffer 104 to the elution buffer 108, via the wash buffer 106 and the intermediate sections of oil 112 inside the rotating valves 216, 218. The rotating valves 216, 218 could be rotated either simultaneously or sequentially. In a fifth step, the beads are transported from the lysis buffer 104 into the wash buffer 106, via the oil 112 inside the first rotating valve 216. The oil 112 in the first rotating valve 216 helps to remove the lysis buffer 106 from the surface of the beads 102. The wash buffer 106 removes the remaining lysis buffer 104 from the surface of the beads 102, and also helps to remove any unwanted biological or chemical species from the surface of the beads 102. In a sixth step, the beads 102 are transported from the wash buffer 106 to the elution buffer 108, via the oil 112 inside the second rotating valve 218. The oil inside the second rotating valve 218 helps to remove the wash buffer 106 from the surface of the beads 102, before the beads 102 pass into the elution buffer 108. The elution buffer causes the target chemical or biological species to be released from the surface of the beads 102 into the elution buffer. In a seventh step, the beads 102 are transported out of the elution buffer 108. For example, the beads 102 may be transported back to the lysis buffer 104 or wash buffer 106. In an eighth step, the second rotating valve 218 is rotated into the closed position. Optionally, the first rotating valve 216 may also be rotated into the closed position. In a ninth step, the plunger 318 is pushed into the cavity 322 (e.g. manually by a user, or using a linear actuator) that contains the elution buffer 108, causing the elution buffer 108 to be ejected from the cavity 305 that contains the elution buffer 108. The ejected elution buffer 108 could be ejected into a test tube or well for storage, for testing at a later time. Alternatively, the elution buffer 108 could be ejected to a testing device for performing a suitable test or analysis on the ejected liquid. For example, the elution buffer 108 could be ejected to a device (which may be connected to the cartridge 200) for performing an amplification based (e.g. PCR or LAMP) DNA test. Whilst in this example both the first and second rotating valves 216, 218 are rotated into the open position in the fourth step, alternatively only the first rotating valve 216 could be rotated into the open position at this stage and the second rotating valve 218 may remain in the closed position. The first rotating valve 216 could be rotated back into the closed position after the beads have been transported into the wash buffer in the fifth step. The second rotating valve 218 could be opened between the fifth step and the sixth step, to allow the beads to be moved into the elution buffer 108 via the oil 112 inside the second rotating valve. The first rotating valve 216 and the second rotating valve 218 may both be closed when the beads are in the wash buffer in the fifth step, to enable mixing of the beads within the wash buffer whilst preventing inadvertent mixing of the liquids inside the cartridge. Whilst in this example the beads 102 are transported out of the elution buffer 108 before the elution buffer 108 is ejected, this need not necessarily be in the case. Alternatively, for example, a magnetic field could be used to retain the beads within the cartridge 200 as the elution buffer 108 is ejected. Moreover, even when the beads 102 are transported out of the elution buffer 108 before the elution buffer 108 is ejected, the magnetic field could nevertheless be used to ensure that beads 102 are not ejected with the elution buffer 108, in case not all of the beads were transported out of the elution buffer 108 before the ejection. Whilst in this example the beads 102 are driven through the cartridge 200 by moving a magnet, this need not necessarily be the case. Alternatively, for example, the beads 102 could be transported through the cartridge 200 using a magnetic field from an electromagnet. As described above, the liquids used in the cartridge 200 are not limited to a lysis buffer 104, wash buffer 106, elution buffer 108 or oil 112, and any other suitable liquids could alternatively be used. Moreover, any suitable number of chambers and valves could be included. For example, there may be a second wash chamber containing either a different or the same wash liquid, and a third separating valve and corresponding oil chamber. Comparative Example: Sliding Valves Whilst the rotating valves 216, 218 of the cartridge and the use of the O-rings 220 provides particularly good seals between the liquids, and provides a reliable mechanism for introducing or removing barriers between the liquids, rotating valves 216, 218 need not necessarily be used. For example, Fig. 33 shows a cross section of a modified cartridge 400 in which linear sliding valves 335 are used, rather than rotating valves 216, 218. As illustrated in Fig. 33, each sliding valve 335 includes a region of oil 112, and adjacent barrier regions 338. A first sliding valve 335a is illustrated in a closed position, in which the barrier region 338a is arranged in between the lysis buffer 104 and a region of oil 112. A second sliding valve 335b is illustrated in an open position, in which a region of oil 112 inside the sliding valve 335b is aligned with the oil 112 in the path for the beads 101 along the cartridge 400, and is aligned with a region of wash buffer 106 inside the cartridge 400. Third 335c and fourth 335d sliding valves are illustrated in the closed position, in which the barrier regions 338 of the sliding valves prevent mixing between the adjacent liquids. Each of the sliding valves 335 may be moved between the open and closed positions using a respective handle 337. For example, a user may manually push or pull the handle 337 to operate the sliding valve 336, or the handle could be gripped and operated by a mechanical device (e.g. comprising a linear actuator or cam). It will be appreciated that that when the sliding valves are in the open position, there is a path for the beads to be transported in the longitudinal direction along the cartridge 400, from the lysis buffer 104 to the elution buffer 108 via the wash buffer 106, and via the intermediate regions of oil 112. When the sliding valves 335 are in the closed position, the barrier region 338 of each sliding valve 335 prevents the adjacent liquids from mixing. Whilst in the example illustrated in Fig. 33 the barrier region 338 is schematically illustrated as a block of solid material inside the sliding valve, this need not necessarily be the case. Alternatively, the barrier 338 may be the wall of the sliding valve, and an aperture may be provided in the wall of the sliding valve 335 adjacent to the region of oil 112 inside the valve 335. The sliding valves may also comprise overmolded gasket regions. Advantageously, the sliding valves 335 are mechanically simple and intuitive to operate. In a further alternative, rather than providing the cartridge 400 with sliding valves 335, melted wax could be used, as described above. For example, the wax could initially be in a solid state, forming the barriers between each of the liquids in the cartridge. The wax could then be heated, to cause the wax to melt into a liquid state for transport of the beads 102 through the wax. Whilst in the present example regions of oil 112 are provided between the first 335a and second 335b sliding valves, and between the third 335c and fourth 335d sliding valves, this need not necessarily be the case. Alternatively, these separate regions of oil 112 could be omitted. In this case, only two sliding valves are needed to maintain separation of the lysis buffer 104, wash buffer 106 and elution buffer 108: a first sliding valve containing oil 112 arranged between the lysis buffer 104 and the wash buffer 106, and a second sliding valve containing oil 112 arranged between the wash buffer 106 and the elution buffer 108. In this case, the width of the sliding valves may be wider than illustrated in Fig. 33 to increase the width of the oil between the other liquids (but this need not necessarily be the case). Comparative Example: Membrane Valves Figs. 34a to 36 illustrate a further alternative in which membrane valves are used to separate the liquids. Fig. 34a shows a cross-cross sectional view of the modified cartridge 500 in which membrane valves are used. As shown in the figure, a membrane 508 is provided above a base portion 509 of the cartridge 500. The liquids (e.g. the lysis buffer 104, wash buffer 106, elution buffer 108 and oil 112) are provided in a channel 510 between the membrane 508 and the base portion 509. In use, the membrane 508 can be pressed against the base portion 509 to form barriers between the liquids. In this example, the cartridge 500 is provided with a thread 501 for receiving a threaded swab (e.g. as described above with reference to Fig. 5) or a threaded cap, but this need not necessarily be the case. A swab tip 242 is illustrated inside a chamber that contains lysis buffer 104. Each of the membrane valves 502 is illustrated in the open position in Fig. 34a, in which there is a path for the beads to be transported from the lysis buffer 104 to the elution buffer 108, via the wash buffer 106 and the intermediate regions of oil 112. As illustrated in Figs 34a and 34b, four membrane valves 502 are provided, at positions B. C, D and E shown in the figure. In order to move the membrane valves 502 into the closed position, the user (or a mechanical device) grips a handle 506 of the cartridge 500, and slides the handle along the longitudinal direction of the cartridge 500 (towards the right-hand side of Fig. 34a). This causes a sliding member 504 to move along the length of the cartridge 500. As illustrated in Fig. 34a, the sliding member 504 has a sloped surface provided adjacently to each membrane valve 502. As the sliding member 504 is moved into the closed position, each sloped surface pushes against the respective membrane valve 502, to push the membrane valve 502 against the membrane 508. This causes the membrane 508 to become pinched between the base 509 of the cartridge 500 and the membrane valves 502, to form the barriers 512 illustrated in Fig. 34b. It will be appreciated that the handle 506 or the sliding member 504 may be provided with a lock or latch, to lock the sliding member 504 (and therefore the membrane valves 502) in the open position or the closed position. Whilst in the example illustrated in Fig. 34a the cam-like engagement between the valves and the sliding member 504 is configured such that all of the valves are opened and closed simultaneously, this need not necessarily be the case. Alternatively, one or more valves may open sequentially by varying the profile and position of each cam surface of the sliding member. Moreover, rather than the state of each of the valves being controlled by a single sliding member 504, alternatively each of the valves 502 may be individually actuatable. For example, a threaded bolt or cylinder may be provided above each valve 502, and rotation of each bolt or cylinder could be used to open and close each valve 502 independently. Each valve 502 could also be controlled to open and close using electromagnetic actuation (e.g. using a solenoid or linear actuator). In the example illustrated in Fig. 34b, the regions of the channel 510 that contain the wash buffer 106 and the elution buffer 108 are relatively wide compared to the other regions of the channel that contain the other liquids. However, this need not necessarily be the case. Also illustrated in Fig. 34b are oil injection locations 514, 518 at which oil 112 could be injected into the cartridge 500 to fill the corresponding sections of the channel 510. Similarly, a wash buffer injection location 516 and an elution buffer injection location 520 are also illustrated. However, it will be appreciated that the liquids could be filled into the cartridge 500 in any other suitable manner. In use, the membrane valves 502 can be moved into the closed position by sliding the sliding member 504 in the direction indicated by the arrow in Fig. 34b, causing the sliding member 504 to press the membrane valves 502 against the membrane 508, resulting in the membrane pinching against the base portion 509 and forming the barriers. Advantageously, this helps to prevent the liquids in the cartridge 500 from mixing (e.g. mixing caused by vibration during transport). The user then inserts the swab tip 242 into the lysis buffer 104, causing the target chemical or biological species to be released into the lysis buffer 104. The membrane valves can then be moved into the open position, removing the barriers between the liquids, and enabling the magnetic beads 102 to be transported from the lysis buffer 104 to the elution buffer 108, via the intermediate regions of oil 112. As illustrated in Figs. 35 and 36, in this example a plurality of screws 521 are provided around the edge of the cartridge 500. The screws 521 are tightened to push an upper portion 503 of the cartridge 500 against the base portion 509 of the cartridge 500, compressing the membrane 508 between the upper portion 503 and the base portion 509. This compression of the membrane 508 (generally around the perimeter of the cartridge 500) reduces the risk of the liquids leaking from the cartridge 500. Alternatively, any other suitable means for securing the upper portion 503, the base portion 509 and the membrane 508 could be used, for example a snap fit, ultrasonic welding, or an adhesive. As shown in Figs. 34a and 35, the cartridge 500 may be provided with a plunger 511 for ejecting the elution buffer 108 (e.g. by pushing the plunger 511 against the membrane 508 to push the membrane into the channel 510 when the membrane valves 502 are in the closed position). Comparative Example: Quarter-Turn Valves Whilst in some of the examples described above O-rings 220 are provided adjacent to the rotating valves 216, 218, to improve the strength of the seals and reduce the risk of the liquids mixing or leaking from the cartridge 200, this need not necessarily be the case. For example, Fig. 37 shows a view of a modified cartridge 600 in which O-rings are not provided. In this example, the first region of oil 112 is provided inside a first quarter-turn valve 602a, and the second region of oil 112 is provided inside a second quarter-turn valve 602a. The quarter-turn valves 602 can be moved between the open and closed positions in the same manner as the rotating valves 216, 218 described above. Whilst the provision of O-rings 220 is preferred to reduce the risk of the liquids mixing or leaking, the cartridge of 600 of Fig. 37 in which no O-rings 220 are provided is particularly simple and straightforward to manufacture. Modifications and Alternatives Detailed embodiments and some possible alternatives have been described above. As those skilled in the art will appreciate, a number of modifications and further alternatives can be made to the above embodiments whilst still benefiting from the inventions embodied therein. It wil! therefore be understood that the invention is not limited to the described embodiments and encompasses modifications apparent to those skiHed in the art lying within the scope of the claims appended hereto. Whilst in some examples described above the cavities containing the oil and the wash buffer have a constant cross-sectional shape along the longitudinal length of the cartridge, this need not necessarily be the case. Alternatively, each of the cavities for al! or any of the lysis buffer, oil, wash buffer of elution buffer may have a cross-sectional shape that varies along the longitudinal length of the cartridge. For example, Fig. 34b shows an example in which a region of larger cross-sectional area is provided, and a similar region could be provided for any of the other cavities described above. In the example of Fig. 34b, the change in cross-sectional area is achieved by varying the width of the cavity, which is particularly advantageous since it allows the cross-section area of the cavity to be varied without varying the vertical height of the cavity (and therefore when the magnet is arranged generally below the apparatus, the height of liquid above the magnet remains constant, helping to achieve consistent mixing through the liquids along the longitudinal length of the cartridge). Nevertheless, the cross-sectional area of any of the cavities could alternatively be varied by varying the vertical height of the cavity along the longitudinal length of the cartridge. Advantageously, varying the vertical height of the cavity provides a region at the top of the cavity into which air bubbles can migrate, reducing the risk that the beads will encounter the air bubbles as the beads are transported along the cartridge. Any of the cavities described above need not necessarily be linear, and could for example have a serpentine or circular shape. Any of the cavities described above may have cavity walls formed of fluorinated plastic to help reduce evaporation of the liquids from the cartridge. Any of the cavities described above may have cavity walls comprising a hydrophobic or hydrophilic coating. Whilst in the above examples the device 200 is illustrated as comprising two rotating valves 216, 216, the number of rotating valves is not limited to two. More generally, the device 200 may comprises as many cavities and valves as needed for the particular use case. For example, some sample types or molecules may require an additional wash liquid, in which case there may be four buffers / reagents and three rotating valves. Moreover, each rotating valve may have more than two positions, and may be, for example, a rotary three-way valve. In this case, the rotating valve may selectively provide a path for the beads into two or more regions. It will be appreciated that the reagents (e.g. the liquids, substances provided in the liquids, or coatings of the beads 102) in any of the above-described examples may comprise any suitable chemical substances, and are not limited to a lysis buffer 104, wash buffer 106, or elution buffer 108. One of the reagents may be a lyophilized colorimetric detection reagent for determining the presence or absence of the targeted biomolecules via colorimetric analysis. The lysis buffer may be similarly lyophilized, wherein the method includes the addition of liquid prior to the sample being introduced, or alternatively the liquid sample itself could provide the rehydration. The reagents may comprise various chemicals or other species (e.g. enzymes, primers, etc.), and mixtures thereof, e.g. for use in nucleic acid amplification methods. For example, a nucleic acid amplification method may comprise polymerase chain reaction (PCR), reverse transcription PCR (RT-PCR), quantitative PCR (qPCR), reverse transcription qPCR (RT-qPCR), nested PCR, multiplex PCR, asymmetric PCR, touchdown PCR, random primer PCR, heminested PCR, polymerase cycling assembly (PCA), colony PCR, ligase chain reaction (LCR), digital PCR, methylation specific-PCR (MSP), co-amplification at lower denaturation temperature-PCR (COLD-PCR), allele-specific PCR, intersequence-specific PCR (ISS-PCR), whole genome amplification (WGA), inverse PCR, or thermal asymmetric interlaced PCR (TAIL-PCR). The nucleic acid amplification reaction may be a nucleic acid isothermal amplification method. Isothermal amplification is a form of nucleic acid amplification which does not rely on the thermal denaturation of the target nucleic acid during the amplification reaction and hence does not require multiple rapid changes in temperature. Isothermal nucleic acid amplification methods can therefore be carried out inside or outside of a laboratory environment. A number of isothermal nucleic acid amplification methods have been developed, including but not limited to Strand Displacement Amplification (SDA), Transcription Mediated Amplification (TMA), Nucleic Acid Sequence Based Amplification (NASBA), Recombinase Polymerase Amplification (RPA), Rolling Circle Amplification (RCA), Ramification Amplification (RAM), Helicase-Dependent Isothermal DNA Amplification (HDA), Circular Helicase-Dependent Amplification (cHDA), Loop-Mediated Isothermal Amplification (LAMP), Single Primer Isothermal Amplification (SPIA), Signal Mediated Amplification of RNA Technology (SMART), Self-Sustained Sequence Replication (3SR), Genome Exponential Amplification Reaction (GEAR) and Isothermal Multiple Displacement Amplification (IMDA). One or more of the reagents may comprise components for making any of the aforementioned amplification chemistries compatible with pH-based or colorimetric detection (e.g. pH-LAMP). This may be accomplished, for example, by reducing buffer capacity (possibly through the absence of tris-HCL). The liquids may comprise an amplification indicator substance, which may be an organic or inorganic compound that is added to a nucleic acid amplification reaction mix so that the content of the solution (such us, for example, the presence or absence of specific nucleic acids) can be determined visually. The amplification indicator substance may be a metal ion indicator (also called a complexometric indicator or metallochromic indicator), which is a substance that changes colour after forming a metal ion complex with a colour different from that of the uncomplexed indicator (such as, for example, but not limited to, Ca2+, Mg2+, Zn2+, and other metal ions). Other amplification indicator substances are possible, that will be familiar to those skilled in the art, such as, for example, but not limited to, hydroxynaphthol blue, eriochrome black t, calmagite, curcumin, fast sulphon black, hematoxylin, murexide, xylenon orange, BAPTA, BAPTA AM, BTC, BTC AM, Calcein, Calcein AM, Calcein Blue, Calcium Green 1, Calcium Green 2, Calcium Green 5N, Coelenterazine, Coelenterazine cp, Coelenterazine f, Coelenterazine h, Coelenterazine hep, Coelenterazine n, CoroNa Green, Corona Green AM, CoroNa Red, DAF FM, Fluo 3, Fluo 3 AM, PBFI AM, Phen Green SK, Quin 2, Quin 2 AM, and RhodZin 3. The amplification indicator substance may be a pH indicator. As those skilled in the art will appreciate, a pH indicator is a chemical detector for hydronium ions (H3O+) or hydrogen ions (H+). Indicators often cause the colour of the solution to change depending on the pH. However, it will be appreciated that indicators can also indicate change via changes in other properties. For example, olfactory indicators indicate change via changes in their odour. Other possible amplification indicator substances include for example, but are not limited to: gentian violet, malachite green, thymol blue, methyl yellow, bromophenol blue , congo red, methyl orange, screened methyl orange (first transition), screened methyl orange (second transition), Bromocresol green, methyl red, methyl purple, azolitmin red, bromocresol purple, bromothymol blue, phenol red, neutral red, naphtholphthalein, Cresol red, Cresolphthalein, Phenolphthalein, Thymolphthalein, Alizarine Yellow R yellow, and Indigo carmine. The amplification indicator substance may be a redox indicator (also called an oxidation-reduction indicator), which is an indicator dye that undergoes a definite colour change at a specific electrode potential. Two common types of redox indicators are pH independent redox indicators and pH dependent redox indicators. pH independent redox indicators include, but are not limited to, 2,2'-bipyridine, Nitrophenanthroline, N-Phenylanthranilic acid, 1,10-Phenanthroline iron(ll) sulfate complex, N-Ethoxychrysoidine, 2,2'-Bipyridine, 5,6-Dimethylphenanthroline, o-Dianisidine, Sodium diphenylamine sulfonate, Diphenylbenzidine, Diphenylamine, and Viologen. pH dependent redox indicators include, but are not limited to, Sodium 2,6-Dibromophenol-indophenol, Sodium o-Cresol indophenol, Thionine, Methylene blue, Indigotetrasulfonic acid, Indigotrisulfonic acid, Indigo carmine, Indigomono sulfonic acid, Phenosafranin, Safranin, and Neutral red.

Claims

1. Apparatus for extracting a chemical or biological species from a sample, the apparatus comprising:a first liquid in a first region;a second liquid in a second region, wherein the second liquid is immiscible with the first liquid; andbeads for transporting the chemical or biological species;wherein the apparatus is configurable between:a first configuration in which there is a path for transport of the beads from the first liquid in first region to the second liquid in the second region, anda second configuration in which a barrier is provided between the first region and the second region.

2. The apparatus according to claim 1,wherein the second region is provided within a first rotating valve;wherein the apparatus is operable for rotation of the first rotating valve between an open position corresponding to the first configuration and a closed position corresponding to the second configuration;wherein when the first rotating valve is in the open position there is a path for transport of the beads from the first liquid in first region to the second liquid in the second region; andwherein when the first rotating valve is in the closed position, a wall of the first rotating valve forms the barrier.

3. The apparatus according to claim 1 or 2,wherein the apparatus further comprises a third liquid in a third region;wherein the third liquid is immiscible with the second liquid;wherein when the apparatus is in the first configuration there is a path for transport of the beads from the second liquid in the second region to the third liquid in the third region; andwherein when the apparatus is in the second configuration a barrier is provided between the second region and the third region.

4. The apparatus according to claim 3 when dependent on claim 2, wherein when the first rotating valve is in the open position the beads can be transported from the first liquid in the first region to the third liquid in the third region via the second liquid in the second region.

5. The apparatus according to claim 4, wherein the third liquid comprises a wash buffer.

6. The apparatus according to any one of claims 3 to 5;wherein the first rotating valve comprises a fifth port provided on an upper surface of the first rotating valve; andwherein the apparatus is configured, when the first rotating valve is in the closed position, for flow of the third liquid into the fifth port to fill the third liquid in the third region.

7. The apparatus according to any one of claims 4 to 6, wherein the apparatus further comprises:a fourth liquid in a fourth region; anda fifth liquid in a fifth region;wherein the fourth region is provided within a second rotating valve;wherein the apparatus is operable for rotation of the second rotating valve between an open position corresponding to the first configuration and a closed position corresponding to the second configuration;wherein when the second rotating valve is in the open position there is a path for transport of the beads from the third liquid in third region to the fifth liquid in the fifth region via the fourth liquid in the fourth region;wherein when the second rotating valve is in the closed position a wall of the second rotating valve forms a barrier between the third region and the fourth region; andwherein when the second rotating valve is in the closed position the wall of the second rotating valve forms a barrier between the fourth region and the fifth region.

8. The apparatus according to claim 7, wherein the third liquid and the fourth liquid are immiscible; and wherein the fourth liquid and the fifth liquid are immiscible.

9. The apparatus according to claim 7 or 8, wherein the fourth liquid comprises oil and the fifth liquid comprises an elution buffer.

10. The apparatus according to any one of claims 7 to 9, wherein the apparatus is configured for sequential rotation of the first rotating valve and the second rotating valve to reconfigure the apparatus from the first configuration and into the second configuration, and to reconfigure the apparatus from the second configuration and into the first configuration.

11. The apparatus according to any one of claims 7 to 10, when dependent on claim 6,wherein the second rotating valve comprises a sixth port provided on an upper surface of the second rotating valve; andwherein the apparatus is configured, when the second rotating valve is in the closed position, for flow of the third liquid out of the third region and out of the sixth port.

12. The apparatus according to claim 11, wherein the apparatus is configured for flow of the third liquid out of the apparatus via the sixth port as the third liquid flows into the third region via the fifth port.

13. The apparatus according to any preceding claim, wherein the first liquid comprises a lysis buffer and the second liquid comprises oil.

14. The apparatus according to any preceding claim, wherein the beads are magnetic beads.

15. The apparatus according to any preceding claim, wherein the apparatus is configured for receiving the sample in the first region, wherein the sample is a liquid sample.

16. The apparatus according to any one of claims 1 to 14,wherein the apparatus is configured for receiving the sample in the first region; andwherein receiving the sample in the first region comprises receiving a swab tip in the first region.

17. The apparatus according to claim 16, wherein the apparatus comprises a swab-supporting member arranged for preventing the swab tip from engaging with a base of the first region.

18. The apparatus according to claim 17, wherein the apparatus is configured such that, in use:the first liquid in the first region covers the swab-supporting member when the apparatus is in a generally vertical orientation, andthe first liquid in the first region does not cover the swab-supporting member when the apparatus is in a generally horizontal orientation.

19. The apparatus according to any one of claims 16 to 18, wherein the apparatus is configured such that, in use, when the swab tip is in the first region:the first liquid in the first region covers the swab tip when the apparatus is in a generally vertical orientation, andthe first liquid in the first region does not cover the swab tip when the apparatus is in a generally horizontal orientation.

20. The apparatus according to any preceding claim, wherein the first region has a tapered shape along the longitudinal length of the apparatus.

21. The apparatus according to any one of claims 7 to 20, wherein the apparatus further comprises:a first O-ring that is arranged at an interface between the first region and the first rotating valve;a second O-ring arranged at an interface between the first rotating valve and the third region;a third O-ring arranged at an interface between the third region and the second rotating valve; anda fourth O-ring arranged at an interface between the second rotating valve and the fifth region.

22. The apparatus according to claim 21,wherein the first rotating valve is arranged for rotation within a sixth region, and the second rotating valve is arranged for rotation within a seventh region;wherein the first O-ring and the second O-ring are arranged between the wall of the first rotating valve and a wall of the sixth region; andwherein the third O-ring and the fourth O-ring are arranged between the wall of the second rotating valve and a wall of the seventh region.

23. The apparatus according to claim 22, wherein the sixth region contains the second liquid; and wherein the seventh region contains the fourth liquid.

24. The apparatus according to claim 23,wherein the apparatus further comprises a fifth O-ring arranged around the first rotating valve and a sixth O-ring arranged around the second rotating valve;wherein the fifth O-ring is arranged to seal the second liquid in the sixth region; andwherein the sixth O-ring is arranged to seal the fourth liquid in the seventh region.

25. The apparatus according to any one of claims 19 to 24,wherein the first O-ring and the second O-ring are engaged with a wall of the first rotating valve, and the third O-ring and the fourth O-ring are engaged with a wall of the second rotating valve;wherein the wall of the first rotating valve is angled such that a compressive force is applied to each of the first O-ring and the second O-ring; andwherein the wall of the second rotating valve is angled such that a compressive force is applied to the third O-ring and the fourth O-ring.

26. The apparatus according to any one of claims 7 to 25,wherein the first rotating valve comprises a first groove or first protrusion in an upper surface of the first rotating valve for engaging with a first rotating member for rotating the first rotating valve; andwherein the second rotating valve comprises a second groove or second protrusion in an upper surface of the second rotating valve for engaging with a second rotating member for rotating the second rotating valve.

27. The apparatus according to claim 26, wherein when the apparatus is in the second configuration the first groove or first protrusion is aligned with the second groove or second protrusion.

28. The apparatus according to any preceding claim, wherein the apparatus further comprises:a first port through which the second liquid can flow into the apparatus to fill the second region; anda second port through which the second liquid can flow out of the apparatus.

29. The apparatus according to claim 28, wherein the apparatus further comprises:a port cover that is moveable between a filling position for filling of the second liquid into the second region, and a closed position for sealing the second liquid inside the apparatus;wherein when the port cover is in the filling position, a first aperture of the port cover is aligned with the first port, and a second aperture of the port cover is aligned with the second port.

30. The apparatus according to claim 29, wherein the first aperture and the second aperture are configured such that as the port cover is moved into the closed position, one of the first port or the second port is sealed closed by the port cover before the other of the first port or the second port is sealed closed by the port cover.

31. The apparatus according to any one of claims 28 to 30, when dependent on claim 23, wherein the first port is further configured for flow of the second liquid into the sixth region.

32. The apparatus according to any one of claims 28 to 31, wherein the apparatus is configured to allow flow of the second liquid out of the apparatus via the second port as the second liquid flows into the second region via the first port.

33. The apparatus according to any preceding claim, wherein the apparatus further comprises at least one gas region, and the gas region is arranged such that gas inside the gas region compresses as the pressure of the second liquid inside the second region increases; orwherein the apparatus further comprises at least one foam disc, and the foam disc is arranged such that the foam disc compresses as the pressure of the second liquid inside the second region increases.

34. The apparatus according to any preceding claim, wherein a base of the apparatus is configured to impart a vertical force component on the beads as the beads are transported longitudinally along the apparatus.

35. The apparatus according to claim 34, wherein the base comprises an undulating surface.

36. The apparatus according to claim 34 or 35, wherein the base comprises ridges, steps, ribs, a wave-like surface, indentations, or a series of grooves.

37. The apparatus according to any one of claims 7 to 36, wherein the apparatus further comprises a plunger for ejecting the fifth liquid from the fifth region via a corresponding aperture.

38. The apparatus according to any preceding claim, wherein the apparatus is configured for receiving the sample in the first region via an opening into the first region;wherein the apparatus comprises a wall inside the first region that defines a sample receiving region that extends from the opening, for receiving the sample; andwherein the wall is configured for preventing the first liquid from flowing out of the opening when the apparatus is in a generally horizontal orientation or when the apparatus is inverted.

39. The apparatus according to any preceding claim, wherein the apparatus is a cartridge for insertion into an automated device for selectively configuring the cartridge into the first configuration or the second configuration.

40. A method of extracting a chemical or biological species from a sample, the method comprising:receiving the sample in the first region of the apparatus according to any of claims 1 to 39;eluting the chemical or biological species from the sample using the first liquid in the first region;configuring the apparatus to be in the first configuration; andtransporting the beads from the first liquid in the first region and into the second liquid in the second region.

41. A method of extracting a chemical or biological species from a sample, the method comprising:receiving the apparatus of claim 39 in the automated device;reconfiguring the cartridge into the first configuration from the second configuration using the automated device; andtransporting the beads from the first liquid in the first region and into the second liquid in the second region using the automated device.

42. The method according to claim 41, wherein the method comprises: receiving the apparatus of claim 39 when dependent on claim 37 in the automated device; andejecting the fifth liquid from the fifth region via the corresponding aperture by using the automated device to actuate the plunger.

43. A method of filling the apparatus according to claim 29, or any claim dependent thereon, with the second liquid, the method comprising:moving the port cover into the filling position; andproviding a flow of the second liquid through the first port, for flow of the second liquid out of the second port via the second region.

44. The method according to claim 43, wherein the method comprises using one or more syringes or pumps to drive the flow of the second liquid through the first port.

45. The method according to claim 43 or 44, wherein the method comprises providing a first flow configuration for flow ofthe second liquid through the first port, for flow of the second liquid out of the second port via the second region; andproviding a second flow configuration for flow of the second liquid through the second port, for flow of the second liquid out of the first port via the second region;wherein the method further comprises alternating between the first flow configuration and the second flow configuration.

46. The method according to any one of claims 43 to 45, wherein the method further comprises moving the port cover into the closed position after the second region has been filled with the second liquid.

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