Microfluidic device for obtaining plasma, including a plural arrangement of microporous membranes

Abstract

The invention relates to a microfluidic device (100) for obtaining an amount of plasma (102), the device comprising: • - a blood-collection module (110) carrying, by means of a membrane holder (113), a first and a second microporous membrane (111A, 111B) that are movable relative to one another, the second membrane (111B) integrally supporting the first membrane (111A), as well as a specific surface (112) arranged downstream of the second membrane (111B); • - a capillary channel (120), which is in fluid connection with the collection module (110) and with a flow outlet (150); • - a reservoir (130) for storing a fluid, which is in fluid connection with the capillary channel (120) and arranged to contain a volume of fluid and include an actuator designed to cause a forced flow of the fluid in the capillary channel (120); and • - a means (140) for preventing any return of fluid to the collection module (110).

Description

[0001] Microfluidic plasma generation device comprising a multiple arrangement of microporous membranes

[0002] The present invention relates generally to the field of blood testing devices. It relates in particular to a microfluidic device for obtaining a quantity of plasma comprising a multiple arrangement of microporous membranes.

[0003] In 2019, according to the World Health Organization, seven of the ten leading causes of death worldwide were chronic diseases, and the percentage of deaths related to such diseases is constantly increasing. Chronic diseases are defined as progressive illnesses lasting several months. Numerous studies have shown that early detection of such diseases increases a patient's chances of survival. For example, in the case of several types of cancer, survival can be more than three times higher when the cancer is diagnosed early (stage one or two).Similarly, early detection of markers linked to acute diseases or symptoms as well as pathogens, such as, for example, the Covid 19 virus, the pathogen associated with Lyme disease or that linked to septicemia or the Human Immunodeficiency Virus (known by the acronym HIV), makes it possible to assess the risk of severe pathological form and to quickly guide management, which may need to be immediate and vital in some cases, in order to promote recovery.

[0004] For this reason, blood biomarkers, or biological characteristics, are attracting increasing interest as indicators of normal or pathological biological processes. Each biomarker has its own specific characteristics that allow it to provide information related to an underlying pathophysiological process and / or data on disease progression. By analogy, biomarkers are to doctors what fingerprints are to police officers: veritable signatures that allow the identification not of an individual, but of a disease. Biomarkers consist of molecules (proteins, hormones, etc.) and cells whose presence or abnormal concentration in the blood, particularly in blood plasma, confirms the existence of a pathology.Blood plasma is the liquid component of blood devoid of red blood cells, white blood cells, platelets and other contaminants, constituting about fifty-five percent of the total blood volume and is thought to contain at least three hundred proteins.

[0005] A biomarker may be present in patients with a specific disease and absent in healthy individuals or those affected by other diseases. However, precise quantification of a biomarker allows it to reflect the progression of a disease. For example, the quantity of a biomarker may increase or decrease depending on whether the disease worsens or improves, and vice versa. Thus, such quantitative indicators allow us to:

[0006] - to refine a prognosis by delivering complete information to characterize a disease (or the presence of a pathogen) in an individual and optimize their management;

[0007] - to adapt the treatment best suited to each patient. In this respect, depending on their metabolism, some people assimilate a medication particularly quickly. In this case, the medication can pass more rapidly into the blood, its effects are increased, and it is therefore necessary to reduce the doses usually prescribed;

[0008] - to monitor the effects of a therapy. For example, in the case of cancer, cancer cells release various molecules into the bloodstream. If their concentration increases over time, this may indicate that the cancer is recurring. Quantifying blood biomarkers therefore appears to be an essential tool for personalized medicine.

[0009] Traditionally, such quantification is possible using the conventional and proven process of blood collection. However, this process requires a significant amount of blood, the intervention of qualified personnel, and the use of specialized equipment, resulting in a costly and time-consuming technique. Indeed, it requires a doctor's prescription for a blood test, scheduling an appointment with a nurse or laboratory (assuming the availability of both healthcare professionals and the patient), waiting for the blood tests to be performed in the laboratory, and the transmission of the results to the doctor, followed by their interpretation.

[0010] To overcome these aforementioned drawbacks, patent application WO 2023 / 179927A1 proposes a microfluidic device for obtaining a quantity of plasma in order to ultimately provide a direct and rapid quantification of a blood biomarker, usable from a drop of blood and which can be implemented by any user, at home, without third-party equipment (centrifuge or other), while ensuring reliability and reproducibility of the results.

[0011] To achieve this, such a device includes a microporous membrane designed to receive a quantity of blood and to separate, by gravity when the microporous membrane is substantially horizontal, the blood components according to their sizes, thus trapping the components other than blood plasma. To optimize the surface characteristics of such a membrane (affecting surface tension, adding surface charge, modifying polarity or hydrophilicity), one or more surface treatments are applied, for example, by wet or dry oxidation, by coating or deposition of a polymer on the surface, or by grafting. However, the quality of such surface treatments of the microporous membrane cannot always be guaranteed, and treatment defects may exist, such as alteration and / or inhomogeneity of the treatment on part or all of the membrane.However, such defects can impact the reliability and filtration efficiency of said membrane by allowing other constituents besides blood plasma, such as red blood cells, to pass through it, contaminating the blood plasma sample to be analyzed.

[0012] The present invention therefore aims to improve upon this observation. To this end, it proposes a microfluidic device for obtaining a quantity of plasma having a multiple arrangement of microporous membranes, in particular double membranes, in order to allow the separation of blood plasma from other blood constituents in an efficient, selective and safe manner, while limiting non-specific interactions of proteins and other analytes contained in the blood.

[0013] To this end, the invention relates to a microfluidic device for obtaining a quantity of plasma comprising:

[0014] - a blood collection module comprising: i. a first microporous membrane arranged to receive a quantity of blood and designed to separate, by gravity when said first membrane is substantially horizontal, the blood constituents according to their sizes and thus trap said constituents other than blood plasma; ii. a second microporous membrane, the first and second microporous membranes being mutually arranged such that:

[0015] - the first membrane is positioned horizontally on the second membrane;

[0016] - each of the first and second membranes comprises an upstream surface (1 1 1 As, 1 1 1 Bs) and a downstream surface, the upstream surface (1 1 1 Bs) of said second membrane (1 1 1 B) fully supporting the downstream surface (1 1 1 Ai) of said first membrane (1 1 1 A); iii. a specific surface (1 12) arranged downstream of said first and second membranes (1 1 1 A, 1 1 1 B) and having hydrophobic, hydrophilic and surface tension properties determined to cause extraction, from said second membrane (1 1 1 B), of said blood plasma (102) filtered by said first and second membranes (1 1 1 A, 1 1 1 B);

[0017] - a capillary channel having a first end in fluidic connection with said collection module, downstream of the specific surface, and a second end in fluidic connection with a flow outlet, said specific surface and said capillary channel being mutually arranged to cause circulation of said blood plasma in said capillary channel;

[0018] - a fluid storage reservoir in fluidic connection with said capillary channel; said capillary channel having determined dimensions between the fluidic connection of said storage reservoir with the capillary channel and said second end of said capillary channel, to control the quantity of blood plasma when the capillary channel is saturated with blood plasma, said storage reservoir being arranged to: i. contain a volume of fluid which, when injected into the capillary channel to entrain the blood plasma, ejects up to the entire volume of blood plasma out of the capillary channel; ii. include an actuator designed to cause a forced flow of said fluid into the capillary channel resulting in a flow of blood plasma through said flow outlet when said actuator is controlled after saturation of the capillary channel with blood plasma;

[0019] - a means of preventing any fluid backflow to the collection module; characterized in that the collection module comprises a membrane holder arranged to allow the first and second membranes to move relative to each other while ensuring continuous surface contact between the downstream surface of the first membrane and the upstream surface of the second microporous membrane. In a preferred embodiment, the first microporous membrane is an asymmetric membrane and the second microporous membrane is an isometric membrane. In accordance with said preferred embodiment, said second membrane preferably comprises pores with a diameter of less than two micrometers.

[0020] Alternatively, the microfluidic device for obtaining a quantity of plasma may further include a mixing chamber connected fluidically to the second end of the capillary channel and to the flow outlet. This mixing chamber is arranged to passively induce a homogeneous mixing of fluids from the capillary channel flowing through the flow outlet. The fluid contained in the storage reservoir is then a reagent intended to be mixed with blood plasma, and the storage reservoir is arranged to hold a volume of reagent greater than the sum of the volumes of fluids that the capillary channel and the mixing chamber can contain.In addition, the storage tank actuator is designed to cause a forced flow of said reagent into the capillary channel resulting in a flow of a homogeneous plasma-reagent mixture through said flow outlet when said actuator is commanded after saturation of the capillary channel with blood plasma.

[0021] The invention will be better understood and other features and advantages thereof will become apparent from the following description of particular embodiments of the invention, given by way of illustrative and non-limiting examples, and with reference to the accompanying drawings, among which:

[0022] - Figure 1 shows a preferred example of the implementation of a microfluidic device for obtaining a quantity of plasma according to the invention;

[0023] - Figure 2 is an illustrative schematic view of the collection module according to the invention;

[0024] - Figures 3, 4, 5 and 6 are schematic views of the device according to the invention illustrating the implementation of said device according to the invention; - Figures 7, 8 and 9 are schematic views of a variant of the device according to the invention.

[0025] To simplify the description, the same reference number is used in different figures to designate the same object or element. Therefore, when the description cites a referenced object or element, that object or element can be identified in several figures. Furthermore, the figures and the description are provided as non-limiting examples of implementation.

[0026] A preferred example of a microfluidic device 100 for obtaining blood plasma, according to the invention, is shown in Figure 1. Said device 100 is composed of at least one blood plasma collection module 110 102 in fluidic connection with a first end 120a of a capillary channel 120, itself in fluidic connection with a storage tank 130 containing a fluid 103. Said fluid 103 may be a gas such as air or an inert gas or any other fluid, another example of fluid will be described later in this description.

[0027] The device 100 further includes a means of preventing any fluid backflow towards the collection module 110, positioned upstream of the fluid connection of the storage tank 130 with the capillary channel 120. The device 100 also includes a flow outlet 150 in fluid connection with a second end 120b of the capillary channel 120.

[0028] The blood plasma collection module 110 is schematically described in Figure 2 and is arranged to receive one or more drops of blood 101, or any quantity of blood 101, or any blood fluid (e.g., pre-treated blood), collected by the user of said device 100. Such a collection module 110 comprises:

[0029] - a first and a second microporous membranes 1 1 1 A and 1 1 1 B through which the collected blood 101 can flow;

[0030] - and a specific surface 1 12 having hydrophobic, hydrophilic and surface tension properties for extracting blood plasma 102 from said microporous membranes 1 1 1 A and 1 1 1 B and circulating said blood plasma 102 in said capillary channel 120.

[0031] The first and second microporous membranes 111A and 111B use the principle of membrane filtration; such membranes act as a physical barrier with calibrated porosity ensuring selective permeability of certain blood constituents below a given size.

[0032] As illustrated in Figure 2, said first microporous membrane 111A is arranged to receive a quantity of blood 101 and to separate, by gravity when said first microporous membrane 111A is substantially horizontal, the constituents of the blood according to their sizes so that white blood cells GB, having a diameter substantially between 12 and 18 micrometers, red blood cells GR, having a diameter substantially between 6 and 8 micrometers, platelets PL having a diameter substantially equal to 2 micrometers and other constituents of large diameter can be substantially trapped in said first membrane 111A in contrast to the blood plasma 102 being able to flow through said first membrane 111A.

[0033] Such a first membrane 111A preferably consists of an asymmetric membrane, in this case a membrane having a pore structure, for example an average pore size, which varies throughout the membrane. As such, said first membrane 111A has an upstream surface 111As and a downstream surface 111Ai with pores of larger cross-sectional dimensions at the upstream surface 111As than at the downstream surface 111Ai. More broadly, for the purposes of the invention, the "upstream surface" of a microporous membrane means the upper surface of said membrane, the surface being the highest when the microporous membrane is positioned horizontally, and the "downstream surface" of a microporous membrane means the lower surface of said membrane, the surface being the lowest when the microporous membrane is positioned horizontally.By way of illustration but not limitation, such a membrane 111A can be characterized by a thickness of 300 to 350 micrometers with an average pore size on the upstream surface 111As of approximately 100 micrometers and 1.8 to 2 micrometers on the downstream surface 111Ai. As an example, membranes of the Pall Vivid® brand are known and available on the market.

[0034] Such a membrane 111A also has one or more surface treatments designed to improve certain of its surface characteristics. Such surface treatments may have defects, such as alteration and / or inhomogeneity of the treatment over part or all of the membrane, and / or increased non-specific interactions with plasma constituents such as proteins, and / or alteration of enzymatic functions, which can lead to altered biomarkers and, consequently, errors in the interpretation of results. Thus, due to these potential defects, some blood constituents 101 that are to be filtered by this first membrane 111A, such as red blood cells (RBCs) and / or platelets (PLs), may nevertheless pass through the membrane 111A with the blood plasma 102, as schematically illustrated in Figure 2.

[0035] Therefore, said collection module 110 further comprises a second microporous membrane 111B positioned horizontally, like the first membrane 111A, and in such a way as to support the entirety of the latter. This second membrane 111B has an upstream surface 111Bs and a downstream surface 111Bi. Thus, this second membrane 111B is arranged to receive the residual blood plasma 102, still potentially "contaminated" by other blood constituents 101, from said first membrane 111A by capillary action in order to complete the filtration.To achieve this, said second microporous membrane 11 1 B preferentially exhibits hydrophilic characteristics in order to draw blood plasma 102 from the first membrane 11 1 A and this second membrane 1 1 1 B allows to separate, by gravity and by capillarity, the last constituents of the blood other than blood plasma 102 (example: red blood cells RBC, platelets PL), which remain trapped in said membrane 11 1 B, from the blood plasma 102, which can flow through said second membrane 1 1 1 B. As such, the "contaminated" blood plasma 102 coming from the downstream surface 1 1 1 Ai of said first membrane 1 1 1 A passes by capillarity at the upstream surface 1 1 1 Bs of said second membrane 1 1 1 B.Advantageously, the upstream surface 111Bs of said second membrane 111B has dimensions, in the longitudinal direction when positioned horizontally, substantially equal to or even greater than the downstream surface 111Ai of said first membrane 111A so that the latter is fully supported by said second membrane 111B and thus guarantee continuous surface contact between the two membranes 111A and 111B. Said upstream surface 111Bs of the second membrane 111B could, however, be slightly smaller to avoid the risk of allowing some constituents to pass through. Furthermore, in order to facilitate the passage of the "contaminated" blood plasma 102 from one 111A to the other 111B, direct contact is preferred; in this case, the space between the two membranes 111A and 111B must be sufficiently small.We therefore seek to minimize the difference between the downstream surface 111Ai of the first membrane 111A and the upstream surface 111Bs of the second membrane 111B. It should be noted that Figure 2 is only a schematic view to illustrate the membrane filtration phenomenon observed with the use of the two membranes 111A and 111B. As such, in such a figure 2, the difference between the two membranes 111A and 111B has been deliberately maximized and is not representative of reality.

[0036] Such a second membrane 111B preferably consists of an isometric membrane, in this case a membrane having a pore structure, for example an average pore size, which is substantially the same throughout the membrane. As such, said second membrane 111B has pores of the same size at the upstream surface 111Bs as at the downstream surface 111Bi. By way of illustration but not limitation, such a membrane 111B may be characterized by a thickness of twenty to twenty-five micrometers, in this case a factor of approximately ten compared to the first membrane 111A, with an average pore size of less than two micrometers over the entire length of said second membrane 111B.For example, polycarbonate membranes treated with polyvinylpyrrolidone (also known as PVP), a hydrophilic polymer that makes the membrane surface hydrophilic, can be used. However, those skilled in the art should not limit themselves to such materials and may consider any other type of material capable of fulfilling this function. Furthermore, such a second membrane 111B may advantageously possess properties that limit non-specific interactions of proteins and / or other analytes contained in blood plasma 102.

[0037] As illustrated in Figures 2 and 3, said specific surface 112 is positioned downstream of the downstream surface 111B of the second membrane 111B and upstream of the first end 120a of the capillary channel 120. Such a specific surface 112 exhibits hydrophobic, hydrophilic, and surface tension properties to draw blood plasma 102 from the second membrane 111B by gravity and to circulate and advance said blood plasma 102 into said capillary channel 120 by capillary action, thus ensuring the continuity of said plasma 102 within said device 100, and not merely its retention. In other words, in order to absorb blood plasma 102 from said second membrane 111B and passively set it in motion within the capillary channel 120, such a specific surface 112 must exhibit an optimized balance between hydrophobic and hydrophilic properties.Indeed, since blood plasma 102 is primarily hydrophilic (composed of approximately ninety percent water) but also contains hydrophobic matter, the specific surface 112 must have a suitable surface tension and be made of a hydrophilic material without being soluble in water. As such, the specific surface 112 can preferably be made of polymethyl methacrylate, a thermoplastic polymer known by the acronym PMMA, which is predominantly hydrophilic (the contact angle with water is approximately sixty-eight degrees) and has a good balance between hydrophobic (methylene) and hydrophilic (carbonyl) groups.However, a person skilled in the art cannot limit themselves to such a material and may consider any other type of material that provides similar or equivalent properties, such as, for example, derivatives of polyacrylamide, polyurethane, poly(hydroxyethyl methacrylamide), or poly(ethylene glycol). As an alternative or complement, it is possible to optimize or even improve the hydrophilic characteristics of the chosen material(s) by using treatments that functionalize the surfaces of said materials, in particular by modifying their surface tension, such as, for example, plasma gas treatments (argon, oxygen, etc.), corona treatments, or even chemical treatments (with sodium hydroxide, polyvinyl alcohol, or hydroxypropyl methylcellulose, etc.).

[0038] Furthermore, in order to concentrate the blood 101 onto said membranes 111A and 111B and to prevent the blood 101 from spreading outside the separation / filtration surface, delimited by the edges of said membranes 111A and 111B, the collection module 110 includes a membrane holder 113 positioned and dimensioned so as to maintain the edges of said membranes 111A and 111B while allowing a (mechanical) gap to permit movement, translation, and / or relative expansion between the two membranes 111A and 111B in a horizontal and a vertical direction, while ensuring continuous horizontal surface contact between the downstream surface 111Ai of the first membrane 111A and the upstream surface 111Bs of the second membrane 11 1 B.This relative clearance prevents membranes 111A and 111B from warping or even swelling under the pressure of the membrane carrier 113. It also allows for the evacuation or expulsion of any air that might be present between the first membrane 111A and the second membrane 111B. This air could create bubbles and prevent cohesion between the water molecules in the plasma. As an illustrative example, for membranes 111A and 111B and a circular membrane carrier 113, the diameter of the membrane carrier 113 will be slightly larger than the diameter of membranes 111A and 111B.

[0039] As illustrated in Figure 3, the capillary channel 120, at its first end 120a, is in fluidic connection with the collection module 110 at the specific surface 112, such that the blood plasma 102 can automatically move from the specific surface 112 to the capillary channel 120 by capillary action, and thus flow vertically (from top to bottom as shown in Figure 3) along said channel 120 from the first end 120a to the second end 120b of said capillary channel 120. The first 120a and second 120b ends of the capillary channel 120 are respectively considered to be the upper and lower parts of said capillary channel 120 when said capillary channel 120 is oriented in space as shown in Figure 3. The blood plasma 102 flows in the capillary channel 120 until it is saturated. The capillary channel 120 has determined dimensions including a predefined length L, as illustrated in figure 4.Said length L corresponds to the defined length between the fluidic connection of said storage reservoir 130 with a third end 120c of the capillary channel 120 and said second end 120b of said capillary channel 120. Said length L thus makes it possible, for a given cross-sectional diameter of said capillary channel 120, to determine and control a quantity of blood plasma 102 when the capillary channel 120 is saturated with plasma 102. A constant and controlled volume of blood plasma 102 is obtained within the capillary channel 120, the quantity of said blood plasma 102 in the capillary channel 120 is thus perfectly dosed.

[0040] For example, for blood plasma volumes 102 on the order of ten to one hundred microliters, the capillary channel 120 can have an internal diameter approximately between 0.3 and 1.5 millimeters and a length L between fifteen and eighty millimeters. Such a capillary channel 120 can be made of glass, plastic, or any other material with suitable characteristics (hydrophilic properties, capillary-enhancing properties, electrostatic properties, and even mechanical properties such as elasticity). However, plastics are preferred because their surface functionalization (allowing, in particular, for increased hydrophilic properties and / or improved capillary action) is easier than for other materials. Furthermore, such a capillary channel 120 can be integrated into the device 100 as a separate component.However, alternatively, in the case where the device 100 comprises a flexible or rigid body, not shown in the figures for simplification purposes, housing the components of said device 100, such as the collection module 110, the capillary channel 120, the storage tank 130, and the flow outlet 150, such components could be created directly by molding or additive manufacturing of said body or by removing material from the latter using laser technology or machining.

[0041] To prevent any reflux or overflow, according to a first method, the means 140 for preventing any fluid backflow to the collection module 110 can consist of a non-return valve. Thus, this valve allows the passage of said blood plasma 102 into the capillary channel 120 from the collection module 110 and prevents any backflow of said plasma 102 from the capillary channel 120 to the collection module 110.

[0042] In another preferred embodiment illustrated in particular in Figures 4 and 5, such a means 140 of preventing any fluidic return can consist of a screw whose stroke causes a "pinching" of said capillary channel 120. Such a screw can thus be actuated, once the capillary channel 120 is saturated with blood plasma 102, in order to put pressure on the capillary channel 120, pinch it and / or close it, thus stopping any flow of blood plasma 102 towards the collection module 110. Manual or motorized actuation of such a screw allows said screw to press against the capillary channel 120 when it is desired to "close" said channel 120 at its first end 120a.

[0043] However, other types of means 140 for preventing any fluid backflow to the collection module 110 could consist, for example, of a valve designed for on / off applications, in which the valve opens or closes depending on the pressure of the fluid passing through it. Examples of such valves are known on the market as guillotine valves or straight-through valves. Such a valve can also be manually operated by the user once the capillary channel 120 is saturated with blood plasma 102, but it is also possible to automate this operation. In the latter case, such a device includes a processing unit, such as a microprocessor, configured to process information from a sensor designed or positioned to detect the saturation of the capillary channel 120 with blood plasma 102 and generate a closing signal for an electrically operated valve.Alternatively, instead of using a sensor, a clock, also known as a "timer" in English, could be used. In this scenario, the closing signal to the electrically operated valve could be triggered after a predetermined elapsed time.

[0044] It should be noted that, because such a means 140 of preventing any fluidic return is positioned upstream of the fluidic connection of said storage reservoir 130 with said capillary channel 120 (i.e. substantially at the level of the first end 120a of the capillary channel 120), this also makes it possible to guarantee all the more the constancy of the volume of blood plasma 102 contained in the part of said capillary channel 120 defined by the length L.

[0045] As illustrated in particular in Figure 5, the storage reservoir 130, in fluidic connection with the capillary channel 120 at the third end 120c of the capillary channel 120, contains a fluid 103 and is arranged to induce the forced flow of said fluid 103 inside the capillary channel 120, inducing the flow of said blood plasma 102 when carried by the fluid 103, due to the saturation of the capillary channel 120 with blood plasma 102, until it reaches said flow outlet 150 which is in fluidic connection with the second end 120b of said capillary channel 120. In other words, such a forced flow of the fluid 103 sets in motion the blood plasma 102 contained in the saturated capillary channel 120, until it reaches said flow outlet 150 which corresponds to an ejection / evacuation outlet of said quantity of plasma 102 to the outside said device 100.

[0046] In this regard, such a storage chamber 130 can be arranged in the form of a syringe fluidically connected to the capillary channel 120 by means, for example, of a capillary tube forming a T-junction 120c with the capillary channel 120. Thus, in such an embodiment, the fluid 103 is contained in said syringe, and the forced flow of said fluid 103 into said channel 120 can be induced by a mechanical movement of a piston 132 of the syringe performed by the user of said device 100. However, those skilled in the art should not be bound by the shape and / or design of such a storage chamber 130. Any other type of storage chamber, such as, for example, a flexible pouch that the user can squeeze, could be used instead of the syringe.Furthermore, such a storage chamber 130 (flexible pouch, syringe or any other type) may contain an actuator 131 arranged to cause a displacement of the piston 132 or a compression thus inducing the forced flow of the fluid 103 into the capillary channel 120, either manually (by the user) or automatically, as for the electrically operated valve described above in order to avoid any fluidic return to the collection module 110. Optionally, the processing unit producing a closing signal of said valve could also produce a control signal of such an actuator 131.

[0047] Furthermore, as illustrated in Figure 6, the microfluidic device 100 for obtaining a quantity of plasma according to the invention is sized so that the volume of fluid 103 contained in the storage chamber 130, when the fluid 103 is injected into the capillary channel 120 to draw in the plasma 102, ejects up to the entire volume of blood plasma 102 from the capillary channel 120. The blood plasma 102 then flows out through the flow outlet 150. In a preferred embodiment of the invention, as shown in Figure 6, it may be possible to collect the quantity of blood plasma 102 obtained on a reagent strip 160 positioned downstream of the flow outlet 150, such as, for example, a lateral flow immunoassay (LFI) test strip.Instead of an LFI 160 test strip, other collectors, such as Eppendorf type tubes of various sizes, 0.2 to 2 millilitres; Greiner tubes for example of Vacuette type; Becton Dickinson tubes for example of Vacutainer type can be used.

[0048] Such a test strip 160 can be used directly by the user to obtain a quantification of the blood biomarker of interest by placing said strip 160 in an optical reader, allowing the user to immediately read / display the quantified result. Thus, an individual wishing to enhance their health monitoring can benefit, from their place of residence or while traveling, from a blood biomarker quantification system comprising a microfluidic device 100 for obtaining a quantity of plasma 102 according to the invention, a test strip 160, and an optical reader. Such a system could include wired or wireless communication means with a remote computer system to transmit quantification results.Such an IT entity may consist of a mobile electronic object (laptop, tablet or smartphone) hosting a software application or appropriate computer program allowing, for example, the recording of results and / or the creation of a medical dashboard or a history of analyses performed.

[0049] In an alternative embodiment as illustrated in Figures 7, 8 and 9, said fluid 103 contained in the storage tank 130 may consist of a reagent whose forced flow within said capillary channel 120 is caused by the actuator 131 of the storage tank 130, causing the flow of said blood plasma 102 into said capillary channel 120. For the purposes of the invention, "reagent" means any fluid enabling certain physico-chemical parameters of the blood plasma 102, such as pH for example, to be made optimal for the conformation of a protein which is the subject of quantification.

[0050] To this end, the microfluidic device 100 according to the invention further comprises a mixing chamber 151 in fluidic connection with the second end 120b of said channel 120 on the one hand and with the flow outlet 150 on the other. Such a mixing chamber 151 is arranged to allow a homogeneous mixing 104 of plasma 102 and the reagent 103. For this embodiment, said microfluidic device 100 according to the invention is then dimensioned so that the volume of said storage tank 130 is greater than the sum of the volumes of said capillary channel 120 and said mixing chamber 151.By way of illustration, but not limitation, such a mixing chamber 151 could have a volume of sixty microliters (corresponding to dimensions of four millimeters in diameter by five millimeters in length) to two hundred and fifty microliters (corresponding to dimensions of five millimeters in diameter by thirteen millimeters in length), and the storage reservoir 130 could have a volume of one hundred to three hundred microliters. Thus, the flow of blood plasma 102 and reagent 103 contained in said capillary channel 120 will occur until the mixing chamber 151 is saturated with the plasma-reagent mixture 104, thereby allowing the flow of a constant plasma-reagent mixture 104 through the outlet 150.

[0051] To promote and facilitate the passive homogenization of the plasma-reagent mixture 104, the mixing chamber 151 may include a network of channels 152 arranged, for example, in zigzags, serpentines, or chevrons. Those skilled in the art should not limit themselves to the design of the mixing chamber 151 that allows for a homogeneous fluidic mixing of the plasma-reagent, as any other type of design or structure could be considered, such as, for example, a micropillar structure.

[0052] It will be appreciated by those skilled in the art that this disclosure is not limited to what is specifically shown and described above. Other modifications may be envisaged without departing from the scope of the present invention as defined by the attached claims.

Claims

DEMANDS 1. Microfluidic device (100) for obtaining a quantity of plasma (102) comprising: - a blood collection module (110) comprising: i. a first microporous membrane (111A) arranged to receive a quantity of blood (101) and designed to separate, by gravity when said first membrane (111A) is substantially horizontal, the blood constituents according to their sizes and thus trap said constituents other than blood plasma (102); ii. a second microporous membrane (111B), the first and second microporous membranes (111A, 111B) being mutually arranged such that: - the first membrane (11 1 A) is positioned horizontally on the second membrane (1 1 1 B); - each of the first and second membranes (111A, 111B) have an upstream surface (111As, 111Bs) and a downstream surface (111Ai, 111Bi), the upstream surface (111Bs) of said second membrane (111B) fully supporting the downstream surface (111Ai) of said first membrane (111A); iii. a specific surface (112) arranged downstream of said first and second membranes (111A, 111B) and having hydrophobic, hydrophilic and surface tension properties determined to cause extraction, from said second membrane (111B), of said blood plasma (102) filtered by said first and second membranes (111A, 111B); - a capillary channel (120) having a first end (120a) in fluidic connection with said collection module (110), downstream of the specific surface (112) and a second end (120b) in fluidic connection with a flow outlet (150), said specific surface (112) and said capillary channel (120) being mutually arranged to cause circulation of said blood plasma (102) in said capillary channel (120); - a storage reservoir (130) of a fluid (103) in fluidic connection with said capillary channel (120), said capillary channel (120) having determined dimensions (L) between the fluidic connection of said storage reservoir (130) with the capillary channel (120) and said second end (120b) of said capillary channel (120), to control the quantity of blood plasma (102) when the capillary channel (120) is saturated with blood plasma (102) and said storage reservoir (130) being arranged to: i. contain a volume of fluid (103) which, when injected into the capillary channel (120) to entrain the blood plasma (102), ejects up to the entire volume of blood plasma (102) out of the capillary channel (120); ii.include an actuator (131) designed to cause a forced flow of said fluid (103) into the capillary channel (120) resulting in a flow of blood plasma (102) through said flow outlet (150) when said actuator (131) is controlled after saturation of the capillary channel (120) with blood plasma (102); - a means (140) for preventing any fluidic return to the collection module (110); characterized in that the collection module (110) comprises a membrane holder (113) arranged to allow the first (111A) and second (111B) membranes to move relative to each other while ensuring continuous surface contact between the downstream surface (1 11 Ai) of the first membrane (1 1 1 A) and the upstream surface (1 1 1 Bs) of the second microporous membrane (1 1 1 B).

2. Microfluidic device (100) for obtaining a quantity of plasma (102) according to the preceding claim, wherein the first microporous membrane (11 1 A) is an asymmetric membrane and the second microporous membrane (1 1 1 B) is an isometric membrane.

3. Microfluidic device (100) for obtaining a quantity of plasma (102) according to the preceding claim, wherein said second membrane (111B) has pores having a diameter of less than two micrometers.

4. Microfluidic device (100) for obtaining a quantity of plasma according to any one of the preceding claims, further comprising a mixing chamber (151) in fluidic connection with on the one hand the second end (120b) of the capillary channel (120) and on the other hand the flow outlet (150), said mixing chamber (151) being arranged to passively cause a homogeneous mixing (104) of fluids from said capillary channel (120) flowing through the flow outlet (150), the fluid (103) contained in the storage reservoir (130) being a reagent (103) intended to be mixed with blood plasma (102),the storage tank (130) being arranged to contain a volume of reagent (103) greater than the sum of the volumes of fluids that the capillary channel (120) and the mixing chamber (151) can contain, and the actuator (131) of the storage tank (130) being designed to cause a forced flow of said reagent (103) into the capillary channel (120) resulting in a flow of a homogeneous plasma-reagent mixture (104) through said, flow outlet (150) when said actuator (131) is controlled after saturation of the capillary channel (120) with blood plasma (102).

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