Apparatus for inducing and / or controlling the flow of a fluid in a microfluidic circuit of a microfluidic device

Abstract

The present invention concerns an apparatus (1) for inducing and / or controlling the flow of a fluid in a microfluidic circuit (200) of a microfluidic device (100) comprising a pumping station (15), comprising a pumping liquid (15') and a pad (5), configured to absorb said pumping liquid (15') present in said pumping station (15), said pad (5) being so adapted to induce a flow of a fluid present in a microfluidic circuit (200) in fluid communication with said pumping station (15), wherein said pad (5) has a three-dimensional shape, adapted to define a three-dimensional absorption volume, partially insertable into, and removable from, said pumping station (15) to induce and / or control the flow of said fluid.

Description

[0001] APPARATUS FOR INDUCING AND / OR CONTROLLING THE FLOW OF A FLUID

[0002] IN A MICROFLUIDIC CIRCUIT OF A MICROFLUIDIC DEVICE

[0003] FIELD OF THE INVENTION

[0004] The present invention concerns an apparatus for inducing and / or controlling the flow of a fluid in a microfluidic circuit of a microfluidic device. In particular, the invention concerns an apparatus, integrated in, or connectable to, a microfluidic device, adapted to start and interrupt the flow of a fluid along a microfluidic circuit for analysis and / or treatment of a biological sample (or not) to be analysed and / or treated by means of said microfluidic device.

[0005] BACKGROUND

[0006] As is known, the flow of a fluid within a microfluidic device can generally be activated by an external pumping system, such as for example, in the simplest case, a syringe, or, alternatively, by exploiting other principles of fluid dynamics, such as for example capillarity, osmosis, force of gravity and fluid surface tension.

[0007] Microfluidic devices find application in different technological sectors, such as for example the fields of microbiology, pharmaceutical engineering and medical diagnostics. In particular, microfluidic devices are increasingly in demand in the field of decentralized diagnostics, that is, diagnostics that are carried out directly at the point of treatment or care of the patient, or at the same patient's home (i.e. the so-called “point-of-care” tests - POC), outside the traditional analysis laboratories.

[0008] Among the various microfluidic devices, the systems that exploit the capillarity of the system as a driving force of the movement of the fluid within the device have received particular attention as they are based on a capillary pump incorporated into the device itself, generally consisting of a sheet, or layer, of thin cellulose-based material, such as paper, and thus easily available and inexpensive.

[0009] This pump induces the fluid to flow along a predetermined path, the microfluidic circuit, through absorption of a so-called working fluid. The capillary absorption process through the cellulose-based material thus produces a depression within the microfluidic circuit, causing the movement of the working fluid itself, within the predetermined path, towards the absorption material, and consequently a movement of the liquid sample also present in the microfluidic circuit.

[0010] The flow of the fluid within the circuit is therefore dependent on the absorption capacity of the thin layer of paper of the capillary pump. Currently, such capillary pumps have a very limited absorption capacity, and consequently only allow the creation of rather simple microfluidic circuits and therefore limited only to certain types of diagnostics.

[0011] Furthermore, in the capillary pumps of known type, as the absorption of the working liquid by the cellulose material increases, the flow of the fluid within the microfluidic circuit decreases its speed until it stops when the paper of the capillary pump is completely impregnated by the working fluid. The current capillary pumps therefore do not ensure accurate control over the flow of the fluid within the microfluidic device, but only “avalanche” type fluid movement, which, moreover, takes place at a variable speed.

[0012] Nevertheless, the increasing complexity of the microfluidic circuits present in the microfluidic devices, where for example the fluid under analysis must be mixed with specific reagents in precise positions of the circuit and at specific time intervals, requires careful control over the flow of the fluid and its movement speed, which is not obtainable at present with the capillary pumps on the market.

[0013] This technical limitation has a negative impact on the possibility of developing new, more complex microfluidic devices, which are still suitable for point-of-care testing applications, where active pumping solutions of the external type cannot be adopted.

[0014] SUMMARY OF THE INVENTION

[0015] In light of the above, the task of the present invention is to realize an apparatus for inducing and / or controlling the flow of a fluid in a microfluidic circuit of a microfluidic device that overcomes the limits of the prior art by allowing to repeatedly induce and / or interrupt the flow of a fluid within a microfluidic circuit, based on the purposes of the microfluidic device.

[0016] An object of the present invention is also to realize an apparatus for inducing and / or controlling the flow of a fluid which operates as a capillary pump with high absorption capacity.

[0017] An object of the present invention is also to realize an apparatus for inducing and / or controlling the flow of a fluid that is able to guarantee a flow rate of the fluid as constant as possible during the phase of use.

[0018] Another object of the present invention is to realize an apparatus for inducing and / or controlling the flow of a fluid in a microfluidic circuit, which can be easily integrated, or connected and disconnected, to any type of microfluidic circuit, so as to realize any type of microfluidic device. A further object of the invention is to realize an apparatus for inducing and / or controlling the flow of a fluid that is capable of giving the broadest guarantees of reliability and safety in use, and furthermore is easy to realize and economically competitive when compared to the known technique.

[0019] The above task, as well as the aforementioned and other purposes that will appear better hereinafter, are achieved by an apparatus for inducing and / or controlling the flow of a fluid in a microfluidic circuit, according to claim 1, as well as by a microfluidic device, according to claim 8, and by a method for inducing and / or controlling the flow of a fluid in a microfluidic circuit, according to claim 9.

[0020] Other features are provided in the dependent claims.

[0021] LIST OF FIGURES

[0022] Further features and advantages will become more apparent from the exemplary but nonlimiting description of a preferred embodiment of the present invention, illustrated with the aid of the attached drawings in which:

[0023] -figure 1 schematically illustrates in perspective from the outside the apparatus for inducing and / or controlling the flow of a fluid, according to the invention, applied to a microfluidic circuit of a microfluidic device;

[0024] -figure 2 shows a plan view from above of the inside of the microfluidic device illustrated in figure 1;

[0025] -figure 3 shows a schematic side view, in transparency, of the microfluidic device of figure 1;

[0026] -figure 4 schematically illustrates in perspective from the outside the microfluidic device of figure 1, in a phase of use in which the fluid absorption pad has been removed from the apparatus to induce and / or control the flow of the fluid itself;

[0027] -figure 5 shows a plan view from above of the inside of part of the microfluidic device of figure 4;

[0028] -figure 6 shows a side view in transparency of the microfluidic device as illustrated in figure 5; -figure 7 shows a perspective view from below of the microfluidic device as illustrated in figure 5;

[0029] -figure 8 illustrates a perspective view of the absorption pad belonging to the apparatus for inducing and / or controlling the flow of fluid, according to the invention;

[0030] -figure 9 is a schematic perspective view of the absorption pad of figure 8;

[0031] -figure 10 reports a schematic perspective view of a second embodiment of a microfluidic device in which the apparatus for inducing and / or controlling the flow of fluid is separated from the microfluidic circuit;

[0032] -figure 11 shows a perspective view, in transparency, of the device as illustrated in figure 5, according to a variant;

[0033] -figures 12 to 18 schematically illustrate different phases of use of the microfluidic device comprising an apparatus for inducing and / or controlling the flow of fluid, according to the invention. In particular:

[0034] -figure 12 schematically illustrates the step of insertion of the fluid to be analysed into the microfluidic circuit;

[0035] -figure 13 schematically illustrates the step of movement of the fluid to be analysed in the mixing station;

[0036] -figure 14 schematically illustrates the step of insertion of the eluent substance into the microfluidic circuit;

[0037] -figure 15 schematically illustrates the step of movement of the eluent substance in the mixing station and of entry of the mixture given by the fluid to be analysed and by the eluent substance in the reaction station;

[0038] -figure 16 schematically illustrates the step of insertion of the reagent into the microfluidic circuit;

[0039] -figure 17 schematically illustrates the step of mixing the reagent with the solution of fluid to be analysed and eluent substance, and of the further movement of the solution of fluid to be analysed and eluent substance in the conduit of connection between the reaction station and the pumping station;

[0040] -figure 18 schematically illustrates the step of movement of the reagent solution, fluid to be analysed and eluent substance in the reaction station and of further possible movement of the eluent substance solution and fluid to be analysed in the pumping station.

[0041] DETAILED DESCRIPTION OF THE INVENTION

[0042] With particular reference to the figures, an apparatus for inducing and / or controlling the flow of a fluid within a microfluidic circuit of a microfluidic device is indicated globally with reference numeral 1.

[0043] Figures 1, 2 and 3 schematically illustrate a microfluidic device 100 comprising a microfluidic circuit 200 and, according to the invention, an apparatus 1 for inducing and / or controlling the flow of a fluid in the microfluidic circuit 200 of the microfluidic device 100 itself.

[0044] The microfluidic device 100 may for example be a so-called “lab-on-a-chip” (LOC).

[0045] The apparatus 1 for inducing and / or controlling the flow of a fluid, hereinafter also defined for brevity's sake as pumping apparatus 1, comprises a pumping station 15 comprising therein a pumping liquid 15’, also defined as working liquid, and a pad 5, configured to absorb, by capillarity, the pumping liquid 15’ present in the pumping station 15. In this way, when a microfluidic circuit 200 of a microfluidic device 100 is placed in fluid communication with the pumping station 15 of the apparatus 1, the pad 5 induces, by absorption, a flow of the fluid present in the microfluidic circuit 200 itself.

[0046] According to the invention, the pad 5 is partially insertable into, and removable from, said pumping station 15 to induce and / or control the flow of said fluid. Furthermore, according to the invention, the pad 5 has a three-dimensional shape adapted to define a three-dimensional absorption volume.

[0047] By the term “three-dimensional” is preferably meant a shape and / or a volume having a spatial extent which, contrary to that of a two-dimensional structure, such as a sheet or a very thin layer of material, has no negligible dimension with respect to the other two orthogonal dimensions.

[0048] In other words, the term “three-dimensional” is preferably understood to mean a shape and / or a volume having a spatial extent such that at least one dimension is at most 25 times larger, preferably at most 20 times larger, than each of the other two orthogonal dimensions of the extent of the shape and / or volume.

[0049] Preferably, the apparatus 1 comprises a fluidic separator 14 configured to place the pumping station 15 in fluid communication with the microfluidic circuit 200. Said fluidic separator 14 is also configured to prevent the passage of the pumping liquid 15’ from the pumping station 15 to the microfluidic circuit 200.

[0050] As illustrated in figures 1 to 7, the microfluidic device 100 may comprise a container body 2, possibly provided with a protruding base 2’, adapted to house therein the microfluidic circuit 200 intended for the treatment and analysis of the fluid to be analysed.

[0051] According to a first embodiment, illustrated in figures 1 to 7, the apparatus 1 can be integrated into the microfluidic device 100 itself and thus in permanent fluid communication with the microfluidic circuit 200.

[0052] According to a second embodiment, illustrated in figure 10, the apparatus 1 is separated from the microfluidic circuit 200 and can be connected (and disconnected) to / therefrom if necessary, so as to realize the microfluidic device 100.

[0053] In essence, therefore, the pumping apparatus 1 maybe an integral part of the microfluidic device 100 or, alternatively, may constitute a separated and separable component of the microfluidic device 100.

[0054] Preferably, the apparatus 1 comprises a seat 4 for housing the pad 5, configured in such a way that, when the pad 5 is inserted in said seat 4, a portion of the pad 5 is arranged in the pumping station 15, in contact with the pumping liquid 15’.

[0055] Preferably, this seat 4 has a shape substantially complementary to the shape of the pad 5 and is configured to facilitate the insertion of the pad 5 and support it in the seat 4 itself.

[0056] As illustrated in figures 1 to 4, the seat 4 can be defined by a housing body 6 protruding towards the outside of the container 2 of the microfluidic device 100.

[0057] The pad 5 has the function of a capillary pump. In fact, when it is inserted in the pumping station 15, it absorbs the pumping fluid 15’ present therein, generating a depression that induces the flow of the fluid present in the microfluidic circuit 200.

[0058] Preferably the pumping station 15 comprises a lower chamber 15” and an upper chamber 15”’ communicating with each other.

[0059] Preferably, the pumping station 15 comprises, in plan, a drop-like shape configured to optimize the filling of the station 15 itself, without stagnation zones.

[0060] Preferably, as illustrated in particular in figures 8 and 9, the pad 5 has a conical or truncated- conical shape, having a height A comprised between 40 and 120 millimetres, preferably comprised between 60 and 100 millimetres, and, more preferably, equal to about 80 millimetres. Preferably the pad 5 has a truncated-conical shape with a circular base, wherein the larger base has a diameter DT comprised between 3.0 and 8.0 millimetres, preferably comprised between 4.0 and 6.0 millimetres, and more preferably equal to about 5.0 millimetres.

[0061] Preferably the pad 5 has a truncated-conical shape with a circular base, wherein the smaller base has a diameter DB comprised between 0.5 and 1.5 millimetres, preferably comprised between 0.8 and 1.2 millimetres, and more preferably equal to about 1.0 millimetres.

[0062] Preferably, therefore, the pad 5 has a three-dimensional shape in which:

[0063] - a first dimension is comprised between 40 and 120 millimetres, preferably comprised between 60 and 100 millimetres, and more preferably equal to about 80 millimetres, and

[0064] - a second and a third dimension, orthogonal to each other and to said first dimension, are each comprised between 0.5 and 8.0 millimetres, preferably between 0.8 and 6.0 millimetres, more preferably between 1.0 and 5.0 millimetres inclusive.

[0065] The pad 5 advantageously has a compact shape adapted to give itself a high absorbent capacity. Preferably the pad 5 is made of a cellulose-based absorbent material, such as for example paper, and has a high absorbent capacity.

[0066] Preferably the pad 5 is obtained from a layer of cellulose-based material rolled on itself and having a thickness comprised between 0.10 and 0.25 millimetres, preferably comprised between 0.15 and 0.20 millimetres and even more preferably substantially equal to 0.175 millimetres.

[0067] Preferably said layer of material is rolled on itself so that the pad 5 assumes a truncated-conical shape.

[0068] Preferably, the seat 4 has a depth of at least 25% of the total height of the pad 5, in order to be able to effectively both guide the insertion of said pad 5 into the pumping station 15, but also support the pad 5 during the step of absorption of the pumping liquid 15’ of the pumping station 15. This depth includes both the height of the part of the seat 4 obtained in the thickness of the container body 2, and the height of the part of the seat 4 obtained in the housing body 6 protruding towards the outside of the container body 2.

[0069] Preferably, the microfluidic circuit 200 comprises at least one inlet port 3, 3’ for fluids, adapted to allow the insertion from the outside into the microfluidic circuit 200 of a fluid and / or of a sample to be analysed and / or of working fluids, such as for example eluent substances and / or reagent.

[0070] Preferably, the microfluidic circuit 200 comprises a mixing station 7 for the inserted fluids, preferably having a coil geometry, such as to favour the mixing of the inserted fluids.

[0071] The microfluidic circuit 200 can also comprise a reaction station 9 configured both to contain the sample fluid to be analysed, previously mixed with any working fluids, and to be able to carry out a possible treatment of the mixture obtained in the mixing station 7 by modifying the physical parameters thereof, such as for example the temperature, by subjecting the mixture to heating by irradiation, as well as to take a reading of the occurred reaction, whose result is, for example, a visible change in one or more physical parameters of the sample to be analysed, such as, for example, the colour of the solution obtained after mixing with the working fluids. Preferably, two valves 8, 10 may be present upstream and downstream of the reaction station 9. In particular, a first capillary stop valve 8 is present upstream of the reaction station 9 and is configured to block the excess flow of the fluids, mixed in the mixing station 7, through a suitable expansion of the cross-section of the channel in the area of the valve 8 itself. A second capillary stop valve 10 is instead present downstream of the reaction station 9, with the function of blocking the flow of the mixture of fluids to be analysed in the reaction station 9, so that the reaction time can have time to end.

[0072] Finally, the microfluidic circuit 200 may comprise a connection conduit 11 adapted to place in fluidic connection the reaction station 9 with the apparatus 1, preferably through the fluidic separator 14.

[0073] Preferably, the fluidic separator 14 comprises a first conduit 14a, substantially developed vertically, in fluid communication with the pumping station 15, a second conduit 14b, substantially developed vertically, in fluid communication with the microfluidic circuit 200, and in particular with the reaction station 9, and more preferably with the connection conduit 11, and a third conduit 14c, substantially developed horizontally, in fluid communication with the first conduit 14a and with the second conduit 14b.

[0074] As illustrated in figures 1 to 6, the fluidic separator 14 therefore has a “bridge” conduit configuration, with one-way valve function adapted to prevent the passage of the pumping liquid 15’ from the pumping station 15 to the microfluidic circuit 200.

[0075] Preferably the conduit 14c, substantially developed horizontally, has a cross-section with smaller area than the cross-section area of the two conduits 14a and 14b substantially developed vertically.

[0076] Furthermore, preferably, said conduit 14c is positioned higher, at a higher elevation, than the pumping station 15, and, in particular, than the upper chamber 15”’, preferably so that, at each point thereof, the conduit 14c is placed above the upper chamber 15’” of the pumping station 15.

[0077] The pad 5, through the depression caused by the absorption of the pumping liquid 15’, therefore has the function of a capillary pump, inducing the flow of the fluid present in the microfluidic circuit 200, in fluid communication with the pumping station 15, through the fluidic separator 14.

[0078] In addition, the peculiar three-dimensional shape of the pad 5 allows an increase in the capacity of the pad 5 itself to absorb fluids, compared to the capillary pumps of the state of the art, based on two-dimensional absorbent structures, having very thin thicknesses.

[0079] As mentioned, the insertion and removal of the pad 4 into / from the relative seat 4 can respectively start the pumping of the fluid and interrupt it.

[0080] This insertion and removal can be carried out manually, by a user or an operator.

[0081] Preferably, according to an embodiment not illustrated, the pumping apparatus 1 comprises a mechanical, electrical, or electromechanical actuator adapted to at least partially insert and remove the pad 5 from the respective seat 4 so as to start or interrupt the pumping of the fluid. Preferably, said actuator can be operated manually, through a button or a switch, by a user or an operator, or can be operated in an automated manner, according to a pre-established analysis procedure.

[0082] Figure 7 reports a perspective plan view from below of part of the microfluidic device 100. The figure also reports some preferable measurements of the various components of the microfluidic device 100, in particular of both the pumping apparatus 1 and of the microfluidic circuit 200, according to an exemplary and non-limiting embodiment.

[0083] Preferably, in the illustrated example, the container 2 has a height of about 5 mm, a length of about 37 mm and a width of about 22 mm, with the protruding base 2’ preferably having a thickness of about 2 mm.

[0084] Preferably, the inlet ports 3, 3’ face onto the upper surface of the container 2, and therefore have a height (or depth) comparable to the height of the container 2 itself. The inlet ports 3, 3’ preferably have a circular section, with a diameter preferably of about 3 mm.

[0085] The fluid flowing channels within the microfluidic circuit 200, in particular the mixing station 7 and the connection conduit 11, preferably have a plan width of about 0.4 mm and a thickness (or depth) of about 0.25 mm.

[0086] The reaction station 9 has, in plan, an enlarged, drop-like, or elliptical shape, and a thickness of about 0.5 mm, slightly larger than that of the mixing station 7.

[0087] The pumping station 15 is instead configured to contain a greater volume of liquid (greater than both the reaction station 9 and the mixing station 7).

[0088] The pumping station 15 has, in plan, an enlarged, drop-like, or elliptical shape, and an overall height that can be of about 2 mm at the upper chamber 15”’, and of about 1 mm at the lower chamber 15”.

[0089] Figure 11 illustrates a variant of a microfluidic circuit 200 of a microfluidic device 100, which comprises, between the mixing station 7 and the reaction station 9, a mixing and drainage station 17 in fluidic connection with a second inlet port 3’. This variant of microfluidic circuit 200 responds to the demand for increasing complexity determined by the need to analyse fluids to be mixed with different and specific reagents, not only in distinct and specific positions within the microfluidic circuit 200, but also at specific time intervals.

[0090] The second inlet port 3’ of the variant illustrated in figure 11 is configured for the insertion of a further substance or reagent into the microfluidic circuit 200, in particular at the mixing and drainage station 17. Said station 17 is configured to mix the substances coming from the mixing station 7 with the fluid inserted into the second inlet port 3’ and the subsequent release of the solution thus obtained towards the reaction station 9.

[0091] The present invention also concerns a microfluidic device 100 comprising an apparatus 1 for inducing and / or controlling the flow of a fluid and a microfluidic circuit 200 for the analysis or treatment of a fluid, in fluid communication with the apparatus 1.

[0092] The apparatus 1 may be integrated into the microfluidic device 100 and in permanent fluid communication with the microfluidic circuit 200.

[0093] Alternatively, the apparatus 1 can be configured to be connected and disconnected if necessary to / from a microfluidic circuit 200, to realize a microfluidic device 100. According to this alternative, therefore, the same pumping apparatus 1 can also be associated, from time to time, to different microfluidic circuits 200.

[0094] In an embodiment not illustrated, the microfluidic device 100 may comprise optical detectors adapted to detect visual changes in the sample to be analysed, suitably treated and / or mixed with working fluids.

[0095] The present invention further concerns a method for inducing and / or controlling the flow of a fluid in a microfluidic circuit 200 of a microfluidic device 100, comprising the steps of: a) having the apparatus 1, as described above, associated with a microfluidic circuit 200 of a microfluidic device 100; b) inserting the pad 5 into the pumping station 15 to absorb the pumping liquid 15’ contained in said pumping station 15, so that this absorption creates, in the pumping station 15, a depression adapted to induce a flow of the fluid present in the microfluidic circuit 200 of the microfluidic device 100; c) removing the pad 5 from said pumping station 15 to interrupt the flow of the fluid present in the microfluidic circuit 200 of the microfluidic device 100.

[0096] The operation of the apparatus for inducing and / or controlling the flow of a fluid in a microfluidic circuit of a microfluidic device is described below, with reference to figures 12 to 18, which illustrate a method for analysing a sample with a microfluidic device 100 equipped with a pumping apparatus 1.

[0097] This method comprises the following steps:

[0098] 1. having an apparatus 1 for inducing and / or controlling the flow of a fluid, as described above and associating it, in case it has not been associated yet, to the microfluidic circuit 200 of a microfluidic device 100, as described above;

[0099] 2. introducing the fluid to be analysed into the first inlet port 3 of the microfluidic circuit 200, as schematically represented in figure 12;

[0100] 3. inserting the pad 5 into the housing seat 4 inside the housing body 6, until reaching the pumping station 15, to absorb the pumping liquid 15’. This absorption creates in the pumping station 15 a depression adapted to induce the movement of the fluid to be analysed towards the mixing station 7 of the microfluidic circuit 200;

[0101] 4. removing the pad 5 from the pumping station 15 to interrupt the flow of the fluid to be analysed once it has invaded the mixing station 7, as schematically represented in figure 13;

[0102] 5. introducing a working substance, in this case an eluent, into the first inlet port 3 of the microfluidic circuit 200, as schematically represented in figure 14;

[0103] 6. inserting again the pad 5 into the pumping station 15 to induce the movement of the eluent substance towards the mixing station 7 of the microfluidic circuit 200 and the mixing of this substance with the fluid to be analysed already present in said mixing station 7;

[0104] 7. removing the pad 5 from the pumping station 15 to interrupt the flow of the mixture, obtained in point 6, once the mixture has reached also the reaction station 9, as well as the mixing and drainage station 17, in an intermediate position between the mixing station 7 and the reaction station 9, as schematically represented in figure 15;

[0105] 8. introducing a further working fluid, in this case a reagent substance, into the second inlet port 3’ of the microfluidic circuit 200, as schematically represented in figure 16; 9. inserting again the pad 5 into the pumping station 15 to induce the movement of the reagent substance towards the intermediate mixing and drainage station 17 of the microfluidic circuit 200 and the mixing of said reagent substance with the mixture given by the fluid to be analysed and by the eluent substance present in said mixing and drainage station 17, as schematically represented in figure 17;

[0106] 10. removing the pad 5 from the pumping station 15 to interrupt the flow of the mixture of fluid to be analysed, eluent and reagent obtained in point 9, once from the mixing and drainage station 17 said mixture has reached also the reaction station 9, as schematically represented in figure 18;

[0107] 11. reading the results of the reaction of the mixture obtained in point 10 in the reaction station 9, for example through a visible change in one or more physical parameters of the sample to be analysed, such as, for example, the colour of the solution obtained after mixing with the working fluids.

[0108] This reaction can also be obtained by a possible further treatment in the reaction station 9 of the mixture obtained in point 10, such as for example a heating by irradiation.

[0109] As shown in figure 18, when the mixture of fluid to be analysed, eluent and reagent has filled the reaction station 9, part of the mixture of fluid to be analysed, with the sole eluent, may eventually invade the connection conduit 11. In further cases, this mixture can also pass beyond the fluidic separator 14 and possibly also reach the pumping station 15, mixing here also with the pumping liquid 15’.

[0110] In practice, it has been found that the apparatus for inducing and / or controlling the flow of a fluid in a microfluidic circuit of a microfluidic device, according to the present invention, fulfils the tasks as well as the intended purposes in that it not only allows to control the flow of fluids within the microfluidic circuit, allowing its start and interruption according to the needs of the reaction of the fluid to be analysed with the working liquids, but also, thanks to the particular three-dimensional structure of the capillary pump, an increase in the movement speed of the fluids within the microfluidic circuit, where this speed remains constant during the use of the microfluidic device.

[0111] Another advantage of the apparatus for inducing and / or controlling the flow of a fluid in a microfluidic circuit of a microfluidic device, according to the present invention, consists in the fact of realizing an apparatus that can be applied to any microfluidic circuit operating with a capillary pump, leading to a considerable saving in using this technology, as well as an increase in the practicality of such microfluidic devices.

[0112] The apparatus for inducing and / or controlling the flow of a fluid in a microfluidic circuit of a microfluidic device thus conceived is susceptible to numerous modifications and variants all falling within the scope of the inventive concept.

[0113] Furthermore, all the details can be replaced by other technically equivalent elements.

[0114] In practice, any materials can be used according to requirements, as long as they are compatible with the specific use, the dimensions and the contingent shapes.

Claims

CLAIMS1. Apparatus (1) for inducing and / or controlling the flow of a fluid in a microfluidic circuit (200) of a microfluidic device (100) comprising a pumping station (15) comprising a pumping liquid (15’) and a pad (5) configured to absorb by capillarity said pumping liquid (15’) present in said pumping station (15), said pad (5) being so adapted to induce a flow of a fluid present in a microfluidic circuit (200) in fluid communication with said pumping station (15) characterized in that said pad (5) has a three-dimensional shape adapted to define a three-dimensional absorption volume, and in that said pad (5) is partially insertable into, and removable from, said pumping station (15) to induce and / or control the flow of said fluid.

2. Apparatus (1) according to claim 1, wherein said three-dimensional shape of said pad (5) has a spatial extent such that at least one dimension is at most 25 times larger, preferably at most 20 times larger, than each of the other two orthogonal dimensions of the extent of said three-dimensional shape of said pad (5).

3. Apparatus (1) according to one or more of the preceding claims, wherein said three- dimensional shape of said pad (5) has no negligible dimension with respect to the other two orthogonal dimensions.

4. Apparatus (1) according to one or more of the preceding claims, wherein said three- dimensional shape of said pad (5) has a three-dimensional shape wherein a first dimension is comprised between 40 and 120 millimetres, preferably comprised between 60 and 100 millimetres, and more preferably equal to about 80 millimetres, and wherein a second and a third dimension, orthogonal to each other and to said first dimension, are each comprised between 0.5 and 8.0 millimetres, preferably between 0.8 and 6.0 millimetres, more preferably between 1.0 and 5.0 millimetres inclusive.

5. Apparatus (1) according to one or more of the preceding claims, comprising a fluidic separator (14), wherein said pumping station (15) is adapted to be placed in fluid communication with said microfluidic circuit (200) through said fluidic separator (14).

6. Apparatus (1) according to one or more of the preceding claims, characterized in that said pad (5) has a conical or truncated-conical shape.

7. Apparatus (1) according to the preceding claim, wherein said pad (5) has:- a height (A) comprised between 40 and 120 millimetres, preferably comprised between 60 and 100 millimetres, and more preferably equal to about 80 millimetres,- a larger circular base having a diameter (DT) comprised between 3.0 and 8.0 millimetres,preferably comprised between 4.0 and 6.0 millimetres, and more preferably equal to about 5.0 millimetres,-a smaller circular base having a diameter (DB) comprised between 0.5 and 1.5 millimetres, preferably comprised between 0.8 and 1.2 millimetres, and more preferably equal to aboutI.0 millimetres.

8. Apparatus (1) according to one or more of the preceding claims, characterized in that said pad (5) is made of a cellulose-based absorbent material, preferably paper.

9. Apparatus (1) according to the preceding claim, wherein said pad (5) is obtained from a layer of cellulose-based material rolled on itself so that said pad (5) assumes said truncated-conical shape.

10. Apparatus (1) according to the preceding claim, wherein said layer of cellulose-based material rolled on itself has a thickness comprised between 0.10 and 0.25 millimetres, preferably comprised between 0.15 and 0.20 millimetres and even more preferably substantially equal to 0.175 millimetres.I I. Apparatus (1) according to claim 5, characterized in that said fluidic separator (14) comprises a first conduit (14a), substantially developed vertically, in fluid communication with said pumping station (15), a second conduit (14b), substantially developed vertically, adapted to be placed in fluid communication with said microfluidic circuit (200), and a third conduit (14c), substantially developed horizontally and positioned at a higher elevation, preferably at each point thereof, than the pumping station (15), in fluid communication with said first conduit (14a) and with said second conduit (14b).

12. Apparatus (1) according to one or more of the preceding claims, characterized in that it comprises a seat (4) for said pad (5) presenting a configuration substantially complementary to the configuration of said pad (5), to favour the insertion and support of said pad (5) in the pumping station (15).

13. Apparatus (1) according to the preceding claim, wherein said seat (4) has a depth equal to at least 25% of the total height of said pad (5).

14. Apparatus (1) according to claim 11, wherein said third conduit (14c) has a crosssection with smaller area than the cross-section area of said first conduit (14a) and of said second conduit (14b).

15. Apparatus (1) according to claim 11 or 14, wherein said third conduit (14c) is positioned at a higher elevation than said pumping station (15).

16. Microfluidic device (100) comprising an apparatus (1) for inducing and / or controlling the flow of a fluid in a microfluidic circuit, according to one or more of thepreceding claims, and a microfluidic circuit (200) for analysis or treatment of a fluid, in fluid communication with said apparatus (1).

17. Method for inducing and / or controlling the flow of a fluid in a microfluidic circuit (200) of microfluidic device (100) comprising the steps of: a) having an apparatus (1) for inducing and / or controlling the flow of a fluid in a microfluidic circuit (200) of a microfluidic device (100) according to one or more of claims 1 to 15, associated with a microfluidic circuit (200) of a microfluidic device (100); b) inserting said pad (5) into said pumping station (15) to absorb said pumping liquid (15’), said absorption creating in the pumping station (15) a depression adapted to induce a flow of the fluid present in said microfluidic circuit (200) of said microfluidic device (100); c) removing said pad (5) from said pumping station (15) to interrupt said flow of fluid present in said microfluidic circuit (200) of said microfluidic device (100).

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