Patent Description:
Liquid chromatography is a technique for the separation of an analyte from a solution. Various forms of liquid chromatography exist, including affinity chromatography and ion-exchange chromatography. Affinity chromatography is typically used for the separation of biochemical analytes, in which an affinity media is selected to have affinity with the analyte of interest. Ion-exchange chromatography separates ions and polar molecules based on their affinity to the ion exchanger, such as a resin with a functional group.

There are some applications where it would be beneficial to be able to perform testing using liquid chromatography techniques in a field environment. One example is the detection of aflatoxin in milk. Milk is collected from a number of dairy farms and processed at a dairy processing facility before distribution for sale. Dairy processing facilities collect and blend milk from a number of dairy farms. Aflatoxin testing is usually only performed at the dairy processing facility, although testing could also be performed at a dairy farm. Testing at the dairy processing facility does not allow identification of whether a specific dairy farm is a source of aflatoxin, since blended milk is tested.

The article "<NPL>) discloses a microfluidc device including meshes and used in a bioassay.

<CIT> relates to an electroosmotic pump including first and second electrodes which, during operation of the pump, are maintained at a potential difference. A membrane intermediate the first and second electrodes includes fibers of an inorganic oxide, such as glass. A surface of the fibers may be functionalized to increase a charge on the membrane with, for example a silane derivative, such as a trialkoxysilane. A fluid in contact with the membrane is drawn through the membrane without the need for moving parts.

<CIT> relates to a three dimensional microfluidic system comprising a plurality of layers stacked upon each other, characterised in that at least one of said layers consists of a 1st and at least one 2nd parts, distinct from each other, with the 2nd part being porous and wettable by a solution of interest, nesting into a recess of the 1st part being non-porous and/or non-wettable by said solution of interest, wherein said system can possibly have a built-in reservoir.

<CIT> relates to capturing particles and includes introducing a fluid sample, which includes particles of a first type, into a first channel of a microfluidic device and flowing the fluid sample past a porous or partially porous membrane. The pores fluidly connect the first channel to a second channel, and the device further includes multiple binding moieties on a first side of the porous membrane adjacent to the first channel. The binding moieties are capable of binding to the first type of particles. Capturing particles also includes creating a pressure difference between the first and second channels to enable the fluid sample to flow from the first channel through the porous membrane into the second channel and to direct the particles toward the binding moieties, thereby capturing the first type of particles.

<CIT> relates to a device for microfluid analyses for a substrate with plane base surface and cover surface, wherein a chamber is integrated in the substrate for receiving liquid with at least two admissions and a semipermeable or permeable membrane is arranged in the chamber, wherein the chamber is subdivided by the membrane into two sectional chambers with at least one admission each.

In accordance with one aspect of this invention, there is provided a microfluidic device according to claim <NUM>.

Preferably, the ratio of a surface area of the outer surface of the mesh to the microfluidic volume is in the region of <NUM>-<NUM>-<NUM>.

In one arrangement, the mesh is formed into a spiral to form the layered configuration.

Preferably, the device further comprises a plurality of groups of meshes, each group of meshes have a different functionalising material applied thereto.

In one arrangement, the plurality of meshes is comprised of a first mesh having a first pitch and a first aperture size, and a second mesh having a second pitch and a second aperture size, wherein the first and second meshes are interleaved. Preferably, the plurality of meshes is further comprised of a third mesh having a third pitch and a third aperture size, the first, second and third meshes being interleaved.

In another arrangement, the each mesh comprises a plurality of apertures having a ranges of sizes and shapes.

Preferably, the plurality of meshes is formed into a stack. A plurality of stacks of meshes may be provided, the stacks being held apart by spacing elements provided between the stacks. Preferably, each stack comprises at least <NUM> meshes.

In one arrangement, the cavity defines a microfluidic volume of <NUM>-<NUM>µL.

The functionalising material applied to the meshes may be selected from the group comprising: phenolic compounds, catechol, gallates, catechin compounds, mussel adhesive protein, antigens including peptide epitopes, aptamers and antibodies, polymer syntheses using DOPA and dopamine derivatives, copolymers formed from acetonide-protected dopamine methacrylamide (ADMA) and one of methyl methacrylate, stearyl methacrylate, glycidyl methacrylate, hydroxyethyl methacrylate and polyethylene glycol methacrylate (PEG methacrylate).

The microfluidic device may further comprise first and second manifold blocks, a body provided between the manifold blocks, the cavity being provided in the body, at least two inlets and at least two outlets provided in the manifold blocks, the inlets and outlets being in fluid communication with the cavity via microfluidic pathways.

Preferably, heating means are provided adjacent to the cavity. The heating means may comprise first and second heaters provided in the first and second manifold blocks, respectively, each heater having a corresponding heating plate provided in the first and second manifold blocks, the heating plates being in thermal contact with the body.

The inlets and outlets may be provided in pairs comprising one inlet and one outlet, one of the inlet and the outlet in each pair provided in the first manifold block and the other provided in the second manifold block, the inlet and the outlet in each pair being aligned, the body being movable between each aligned pair.

In one arrangement, the inlets comprise a sample inlet, a buffer inlet and an elution inlet, and the outlets comprise a sample outlet, a buffer outlet and an elution outlet, to provide a sample pair, a buffer pair and an elution pair.

The first and second heaters may also be aligned, the inlet and outlet pairs and the heaters arranged to form the sequence sample pair, buffer pair, heaters, and elution.

The manifold block may include at least one sensor integrated therein. The sensors may be optical, magnetic, thermal, and/or chemical.

In one arrangement, the sample inlet, buffer inlet and elution outlet are provided in the first manifold block and the sample outlet, buffer outlet and elution inlet are provided in the second manifold block.

Embodiments of the disclosure will now be described, by way of example, with reference to the accompanying drawings in which:.

<FIG> shows a microfluidic device <NUM> according to one embodiment of the disclosure. The microfluidic device <NUM> comprises a body <NUM> in which a cavity <NUM> is formed. The cavity <NUM> defines a microfluidic volume of <NUM>-<NUM>µL, although in other embodiments larger or smaller volumes may be used as required. The cavity <NUM> extends through the body <NUM> to define first and second openings 16a, 16b at ends 18a, 18b of the body <NUM>.

In the embodiment shown in <FIG>, a plurality of meshes <NUM> are provided in the cavity <NUM>. The meshes <NUM> are arranged in a layered configuration as will be described in more detail below. The meshes <NUM> are held in place between gaskets <NUM>. The gaskets <NUM> also ensure a fluid passes through the meshes <NUM> rather than around any gap between the meshes <NUM> and the body <NUM>.

Examples arrangements of meshes <NUM> are shown in <FIG>. Each mesh <NUM> has a plurality of apertures <NUM> formed therein and an outer surface <NUM>. The apertures <NUM> of adjacent meshes <NUM> are offset with respect to one another to define a plurality of circuitous pathways therethrough. The meshes <NUM> shown in <FIG> have a diameter in the range of <NUM>-<NUM>, however other sizes may be used.

The arrangements of meshes <NUM> shown in <FIG> and <FIG> are each comprised of a first mesh 20a in which the apertures <NUM> have a first aperture size and are spaced apart at a first pitch, and a second mesh 20b in which the apertures <NUM> have a second aperture size and are spaced apart at a second pitch. The arrangement of <FIG> further comprises a third mesh 20c in which the apertures <NUM> have a third aperture size and are spaced apart at a third pitch. Example values for the pitch and aperture size of the first, second and third meshes shown in <FIG> are set out below in Table <NUM>.

As shown in <FIG>, the first, second and third meshes 20a-20c are interleaved. Other arrangements that those shown in the drawings are possible, for instance the order and quantity of meshes 20a-20c could be varied and may even be random. The meshes <NUM> may be formed of any suitable material, including nickel, ceramic, polymers, rubber, gold or other suitable metal, or a composite of materials. In some embodiments, the meshes <NUM> may be formed from one of several materials and arranged in an order according to the type of material. The meshes <NUM> are formed from nickel and arranged in a layered configuration such that the meshes are interleaved. The number of meshes and interleave order may be varied.

Each mesh 20a-20c is shown with one size of aperture <NUM> formed therein, while in other embodiments the apertures formed in each mesh may have a range of sizes and/or shapes. Further, other shapes than those shown in the drawings are possible. For example, the apertures in each mesh may have a porosity gradient or other configuration to provide a uniform interaction between the analyte and the outer surface of the meshes. The apertures <NUM> in each mesh <NUM> are arranged in a grid in the examples shown in the drawings, however other arrangements of apertures may be used. It is preferred that one mesh is rotated with respect to an adjacent mesh, as most clearly shown in <FIG>.

The apertures <NUM> define a plurality of circuitous pathways through the meshes <NUM>, as can be seen in <FIG> which is a top view of the meshes <NUM> in <FIG>. The layering and rotating of meshes is considered to enhance this effect since the apertures of adjacent meshes will not be aligned, encouraging transverse movement of a fluid passing through the meshes <NUM>. The plurality of meshes <NUM> is formed into a stack <NUM>, which in the embodiment shown in <FIG> may consist of <NUM>-<NUM> meshes.

The meshes <NUM> provide a large surface area which is beneficial as described below. The ratio of a surface area of the outer surfaces <NUM> of the plurality of meshes <NUM> to the microfluidic volume may be in the region of <NUM>-<NUM>-<NUM> depending on the proportion of the cavity <NUM> filled with meshes.

In other embodiments, a single mesh may be provided in the cavity <NUM> and formed into a spiral to form the layered configuration, for instance by rolling.

Returning now to <FIG>, a functionalising material (not shown) is applied to the outer surface <NUM> of the plurality of meshes <NUM>. Any suitable functionalising material known to those in the art may be used according to the application. The functionalising material may be applied to the meshes <NUM> in any preferred manner. Conveniently, however, the microfluidic device <NUM> is itself suitable for the application of functionalising material, for instance by washing a solution containing the functionalising material through the microfluidic device <NUM>. Where the microfluidic device <NUM> is to be used in an affinity concentrator application, example functionalising materials include phenolic compounds, catechol, catechin compounds, mussel adhesive protein and polymer syntheses using DOPA and dopamine derivatives. As would be appreciated by those in the art, the functionalising material would be chosen to be suitable to the material that the mesh is made from. In some embodiments meshes made from different materials may be used in one device. Further, multiple different functional materials may be used, for example one group of meshes may have a first functionalising material and a second group of meshes may have a second functionalising material. More than two groups may be used. Such arrangements offers the possibility of microfluidic devices with multi-parameter test capability. Further examples of functionalising materials are described in more detail below.

Referring now to <FIG> & <FIG>, a microfluidic device <NUM> according to another embodiment of the disclosure is shown, with like reference numerals denoting like parts to those of the first embodiment. The microfluidic device <NUM> is similar to the microfluidic device <NUM>, with the exception that a plurality of stacks <NUM> are provided in the cavity <NUM> of the microfluidic device <NUM>. The stacks <NUM> are held apart by spacing elements in the form of gaskets <NUM> provided between the stacks <NUM>. In one arrangement, the gaskets <NUM> may be formed of a compressible material, enabling the stacks <NUM> to be provided closer together as shown in <FIG>. In other embodiments gasket may be formed on the mesh by any suitable process, such as additive processes, printing, or lithography. For example, the gaskets may be formed of photoresist and included on the mesh by lithography.

Providing multiple stacks <NUM> increases the total surface area of the meshes <NUM>. In some embodiments, some or all of the gaskets <NUM> could be omitted and replaced with further meshes. As the number of meshes increase, the volume in the cavity occupied by the meshes will increase. The number of meshes <NUM> chosen for a particular application, the pitch and aperture sizes of the meshes and the volume of the cavity <NUM> will be chosen according to factors including the desired concentration to be achieved in affinity applications, any backpressure constraints of other devices such as pumps or connectors, and a desired volume of eluate to be obtained from the cavity <NUM>.

Referring now to <FIG>, a further embodiment of the disclosure is illustrated, with like reference numerals denoting like parts to those of the previous embodiments. The microfluidic device <NUM> of the embodiment comprises a body <NUM> of the same form as shown in <FIG>. The body <NUM> is provided between first and second manifold blocks <NUM>, <NUM> respectively.

The first manifold block <NUM> has a sample inlet <NUM>, a buffer inlet <NUM> and an elution outlet <NUM> formed therein. The second manifold block <NUM> has a waste outlet <NUM> and an elution inlet <NUM> formed therein. Each of the inlets and outlets <NUM>-<NUM> are in fluid communication with the cavity <NUM> via microfluidic pathways <NUM> formed in each manifold block <NUM>, <NUM> as shown in <FIG>. The manifold blocks <NUM>, <NUM> of the embodiment are designed to minimise the length of the pathways. In other embodiments other microfluidic functions may be integrated into the manifold blocks <NUM>, <NUM>, such as those described in <CIT> and <CIT>. Further, the manifold blocks <NUM>, <NUM> that may incorporate one or more sensors via a suitable channel formed in the manifold block, eg via a multilayer construction of the manifold block. The sensor(s) may be embedded in manifold block <NUM>, <NUM> and in contact with one of the pathways <NUM>, such as the pathway <NUM> from the cavity <NUM> to elution outlet <NUM>. The sensor(s) may be optical, magnetic, thermal, chemical, or other sensors according to requirements. Further heating/cooling devices may be integrated into the manifold blocks <NUM>, <NUM>.

Connectors <NUM> are threaded into the each manifold block <NUM>, <NUM> to permit attachment of hoses or other fluid conduits to each inlet and outlet <NUM>-<NUM>.

Each manifold block <NUM>, <NUM> has a recess <NUM>, <NUM>, respectively, formed therein which partially receives the body <NUM>. A gasket <NUM>, <NUM> is received within each recess <NUM>, <NUM>, respectively, to form a seal between the body <NUM> and the corresponding manifold block <NUM>, <NUM>.

Each manifold block <NUM>, <NUM> has a raised portion <NUM>, <NUM>, respectively, that protrudes into the body <NUM>. The meshes <NUM>, and gaskets <NUM> if any are present, are compressed between the raised portions <NUM>, <NUM>. Compression may assist in flattening meshes <NUM> into a more planar form.

The microfluidic device <NUM> may be utilised as a compact, low cost affinity column. A suitable functionalising material is applied to the outer surface of the meshes <NUM>. Conveniently, the meshes <NUM> may be functionalised in situ within the microfluidic device <NUM>. For instance, a solution containing a functionalising material may be passed through the microfluidic device <NUM> using the sample inlet <NUM> and the waste outlet <NUM>, following which a wash solution may be passed through the microfluidic device <NUM>.

A further embodiment of the disclosure is illustrated in <FIG> and <FIG>, with like reference numerals denoting like parts to those of the previous embodiments with any differences described below.

In the microfluidic device <NUM> of the embodiment, the manifold blocks <NUM>, <NUM> are in the form of plates. The body <NUM> is received within a hole <NUM> provided in a guide plate <NUM> positioned between the manifold blocks <NUM>, <NUM>. The guide plate <NUM> has a handle <NUM> which may be used to rotate the guide plate <NUM> relative to the manifold blocks <NUM>, <NUM>. The guide plate <NUM> rotates around a spindle <NUM> projecting from the second manifold block <NUM>.

The first manifold block <NUM> of the microfluidic device <NUM> includes a hole <NUM> though which the spindle <NUM> passes. The sample inlet <NUM>, buffer inlet <NUM> and the elution outlet <NUM> are provided spaced from the spindle <NUM> in an arc thereabout, as can be seen from <FIG>.

The second manifold block <NUM> has a sample outlet <NUM> and a buffer outlet <NUM> in place of the waste outlet of the previous embodiment. The sample outlet <NUM>, buffer outlet <NUM> and the elution inlet <NUM> provided spaced from the spindle <NUM> in an arc thereabout in a similar manner to the inlets and outlets in the first manifold block <NUM>.

The microfluidic device <NUM> has pairs of inlets and outlets, namely a sample pair, a buffer pair and an elution pair. In each inlet and outlet pair, one of the inlet or the outlet is provided in the first manifold block <NUM> and the other of the inlet or outlet is provided in the second manifold block <NUM>. Each inlet and outlet pair is aligned so the body <NUM> can be rotated into alignment with each inlet and outlet pair in turn via the guide plate <NUM>.

To assist with registration between the body <NUM> and each pair, notches <NUM> are formed in the edge <NUM> of the guide plate <NUM>. The notches <NUM> engage a spring-loaded member <NUM> to provide registration indication to a user.

The microfluidic device <NUM> includes heating means arranged to selectively heat the body <NUM> and contents of the cavity <NUM>. As illustrated in the drawings, the heating means of the embodiment includes a first heater <NUM> provided on the first manifold block <NUM> and a second heater <NUM> provided on the second manifold block <NUM>.

Each heater <NUM>, <NUM> comprises a heating plate <NUM> from which a hollow column <NUM> extends. The heating plates <NUM> and columns <NUM> are formed of suitable thermally conductive material, such as aluminium. A thermocouple (not shown) may be provided in each heating plate <NUM> to provide a control signal via cables <NUM>. Insulators <NUM> are provided around the columns <NUM>. A suitable heating device, such as a cartridge heater, is received within each column <NUM>, and may be controlled according to the control signal.

The first and second heaters form a heating pair. In like manner to the inlet and outlet pairs, the first and second heaters <NUM>, <NUM> are spaced from the spindle <NUM>. The first and second heaters <NUM>, <NUM> are also aligned with, the inlet and outlet pairs and the heaters arranged to form the sequence sample pair, buffer pair, heater pair, and elution pair.

The heating plates <NUM> are provided flush with a surface of the manifold blocks <NUM>, <NUM> such that when the body <NUM> is brought into registration with the heaters <NUM>, <NUM>, the heating plates <NUM> are adjacent to the cavity <NUM> and in thermal contact with the body <NUM>.

The first manifold block <NUM> of the microfluidic device <NUM> has a cutaway portion <NUM> formed therein. The cutaway portion <NUM> provides access to the hole <NUM> in the guide plate <NUM> when the guide plate <NUM> is rotated so the hole <NUM> is in registration with the cutaway portion, so a user may insert, remove or replace the body <NUM>.

A further embodiment of the disclosure is illustrated in <FIG>, with like reference numerals denoting like parts to those of the previous embodiments with any differences described below.

In the microfluidic device <NUM> of the embodiment is similar to the microfluidic device <NUM> shown in <FIG> & <FIG>. However, in the microfluidic device <NUM>, the guide plate <NUM> does not have a handle. The spindle of the previous embodiment is replaced with a shaft <NUM> that engages with and rotates the guide plate <NUM>. The shaft <NUM> is driven by a motor <NUM>, such as a stepper motor. The first manifold block <NUM> of the microfluidic device <NUM> has an aperture <NUM> in place of the cutaway portion of the previous embodiment. In a similar manner to the manifold block <NUM> of the device <NUM>, the first manifold block <NUM> of the microfluidic device <NUM> may have microfluidic functionality integrated into it, such as sensors and heating/cooling devices.

<FIG> shows detail of the buffer inlet <NUM>, buffer outlet <NUM>, elution inlet <NUM> and elution outlet <NUM> in cross-section. As shown the buffer inlet and outlet <NUM>, <NUM> are relatively wide to permit fast fluid flow therethrough. The sample inlet and outlet <NUM>, <NUM> are similarly sized to the buffer inlet <NUM> and buffer outlet <NUM>. In contrast the elution inlet and outlet <NUM>, <NUM> include a narrow neck to provide a more controlled flow therethrough during elution of the cavity <NUM>.

<FIG> shows detail of the heaters <NUM>, <NUM>, and illustrates that when the guide plate <NUM> is brought into registration with the heaters <NUM>, <NUM>, the heating plates <NUM> are adjacent to the hole <NUM> so as to be in thermal contact with the body <NUM> provided in the hole <NUM>. The proximity of the heating plates to the body <NUM> permits rapid heating of the contents of the cavity <NUM>, as described in more detail in the examples below.

The microfluidic device <NUM> provides a compact system for performing liquid chromatography in a microfluidic form. The following examples provide results of tests performed using microfluidic devices according to this disclosure. The examples are described with reference to the embodiments shown in <FIG>, although the device shown in <FIG> could also be used. The embodiment shown in <FIG> would also be suitable for use in the examples, however rather than movement to a position as described below, use of the inlets and outlets of the device <NUM> corresponding to the position would be used.

To prepare the device, the guide plate <NUM> is rotated so the hole <NUM> is in registration with the cutaway portion <NUM>. A body <NUM> is inserted into the hole <NUM>, which in the examples contains six stacks <NUM> each consisting of twenty meshes <NUM> arranged as shown in <FIG>, though other arrangements may be used.

Once the body <NUM> is received in the hole <NUM>, the guide plate <NUM> is rotated to a first position in which the body <NUM> aligned with the sample inlet and outlet <NUM>, <NUM>. The body <NUM> is then primed with water at a flow rate of <NUM>-<NUM>/min.

Once primed, if the meshes <NUM> have not been functionalised prior to insertion into the device, the meshes <NUM> are then functionalised by passing a solution containing a functionalising group through the body <NUM> using the sample inlet and outlet <NUM>, <NUM>. The meshes <NUM> were formed of nickel. Functionalising may include coating the outer surfaces <NUM> of the meshes <NUM> by treatment with organic coupling agents with good binding properties to the mesh material. In the case of Ni and Nickel oxide, such coupling agents include catechols and gallates functionalised with moieties such as PEG, hydrocarbon chains (such as stearyl gallate) and functionalised with groups that that will react with antigens including peptide epitopes, aptamers and antibodies synthesised using recombinant protein expression in Escherichia coli antibodies attached to the coupling agents via an epoxy groups or other groups used for binding to aminoacids acids including coating formulations comprising dimer, trimers, monomers, oligomers and polymers including synthetic and naturally occurring polymers containing catechols such as mussel adhesive protein (as described in <CIT>).

Another example of a functionalising material is polymer syntheses using DOPA and dopamine derivatives as a means of imparting the adhesive properties of mussel foot protein into synthetic polymers. Acetonide-protected dopamine methacrylamide (ADMA) may be used as a monomer in the synthesis of copolymers using free radical and reverse addition-fragmentation chain transfer (RAFT) polymerisation. Various co-monomers were investigated, and methyl methacrylate, stearyl methacrylate and glycidyl methacrylate all formed copolymers with ADMA. The co-monomer is chosen to provide attachment to a suitable functional group that has affinity with the analyte, such as peptide epitopes, aptamers and antibodies.

Other suitable functionalising materials include those used in solid phase extraction for HPLC and for immunoaffinity columns for bioassays. Further functionalising materials include self-ordering materials such as lipids and liquid crystals; and proteins such as caseins and bovine serum albumin BSA used as blocking agents for spacing antigens.

The functionalising material is chosen to provide affinity to the analyte of interest. In the examples, the meshes <NUM> were functionalised for affinity to aflatoxin using a functionalising material of mussel adhesive protein or polymer syntheses using DOPA and dopamine derivatives. After functionalising, the meshes <NUM> may be washed by passing a buffer solution through the sample inlet and outlet <NUM>, <NUM>.

Next, a solution that may contain the analyte of interest is passed through the body <NUM> at a flow rate of <NUM> - <NUM>/min. In the example, the body <NUM> defined a cavity <NUM> having a <NUM>µL volume, in which case a flow of <NUM>/min would provide ten evacuations in <NUM> minute. It has been found that increasing the flow rate results in a corresponding increase in back pressure in the body <NUM> due to flow resistance from the meshes <NUM>. This back pressure may assist with capture of the analyte by the meshes <NUM> since the pressure encourages lateral flow across the meshes as well as through the meshes. In the example, <NUM>-<NUM> of solution was passed through the body <NUM>. In some cases, the solution may be pre-treated to remove substances that may interfere with operation of the device. In the case of detection of aflatoxin in milk, the solution consists of <NUM>-<NUM> of milk that has had fat globules removed, for instance using a cross-flow filtration device. Once the solution has been passed through the body <NUM>, the meshes <NUM> are then washed with a buffer solution.

The guide plate <NUM> is then rotated to a second position in which the body <NUM> aligned with the heating plates <NUM>. A gasket (not shown) is provided in a recess <NUM> that surrounds the hole <NUM> on each surface of the guide plate <NUM> to form a seal with the first and second manifold blocks <NUM>, <NUM>. Power is supplied to the heaters <NUM>, <NUM> to heat the buffer in the cavity <NUM> and release the analyte from the meshes <NUM>. The small volume of the cavity <NUM> results in heating occurring at a rate of <NUM>/sec. In the case of aflatoxin, heating is performed to achieve a temperature of <NUM> to release the aflatoxin from the surface mounted antibody and into the buffer in the cavity <NUM>. Heating from <NUM>-<NUM> occurs quickly, in around <NUM> seconds. The guide plate is maintained in this position with the cavity temperature controlled at the desired value for a period of time sufficient to allow the release of the maximum amount of antibody into the buffer. The choice of temperature and time will be informed by the release properties of the surface mounted antibody or other surface treatment used to provide affinity.

The guide plate <NUM> is then rotated to a third position in which the body <NUM> is aligned with the elution inlet and outlet <NUM>, <NUM>. The buffer and analyte is then eluted from the device with a now higher concentration of analyte, typically to detector. Elution is typically performed at a desired flow rate which can be low or high, typically <NUM> - <NUM>µL/s. Elution may be achieved by pumping a gas or buffer liquid. Any suitable detector may be used according to the analyte of interest. During elution the heating plates <NUM> cools at a rate of <NUM>/min ready for the next sample, though this time could be reduced using cooling.

The devices in this example concentrated the aflatoxin to a range that permits detection, for instance using an ELISA (enzyme linked immunosorbent assay) analysis.

Table <NUM> below shows the concentration results achieved in eight example configurations.

Table <NUM> below shows the mesh configurations used in each of the example configurations shown in Table <NUM>.

Depending on the application the concentration factor may be increased by replacing some or all of the gaskets <NUM> with more meshes. In addition, as the examples in tables <NUM> and <NUM> show, the flow rate also influences analyte concentration, with lower flow rates providing increased concentration of the analyte. However, low flow rates also increase the time to pass the solution through the device. The number of meshes <NUM>, the volume of the body, the time at which the cavity is held at the release temperature, and the flow rate may be optimised for the test conditions and desired analyte concentration. A <NUM>-fold increase in concentration beyond that shown in Table <NUM> is expected to be achievable by suitable optimisation.

Desirably each processes would be undertaken a few minutes to provide an overall assay time of less than <NUM> minutes. In one arrangement, the pumps used to pass buffer and solution through the device <NUM> were syringe pumps, providing a low cost chromatography system that could be used in field locations such as dairy farms.

While the examples above have been described with reference to the device <NUM> of <FIG>, it will be appreciated that the device <NUM> of <FIG> may also be used, in which case the steps of rotating the guide plate <NUM> may be performed by the motor <NUM>. Further, the device may be connected to sources of buffer, solution, etc and the process may be automated with suitable control systems and process sensors.

The embodiments illustrated in <FIG> show configurations using a single body <NUM> that is rotated. In other configurations, devices having multiple bodies <NUM> may be provided. In addition, devices employing linear movement rather than rotational movement may be provided.

While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as defined by the claims.

Wherever the term comprising is used herein, we also contemplate options wherein the terms "consisting of" or "consisting essentially of" are used instead.

Claim 1:
A microfluidic device (<NUM>) having a cavity (<NUM>) defining a microfluidic volume, comprising:
a plurality of meshes (<NUM>) provided in the cavity (<NUM>), each mesh (<NUM>) having a plurality of apertures (<NUM>) and an outer surface (<NUM>);
said plurality of meshes (<NUM>) being arranged in a layered configuration with the apertures (<NUM>) of adjacent layers offset with respect to one another to define a plurality of circuitous pathways therethrough, wherein the apertures (<NUM>) in each mesh (<NUM>) are arranged in a grid, whereby the grid of one mesh is rotated with respect to the grid of an adjacent mesh;
the outer surface (<NUM>) of each mesh (<NUM>) having a functionalising material applied thereto;
wherein each mesh (<NUM>) is formed of nickel.