MICROFLUIDIC DEVICE FOR THE PREPARATION OF A PLASMA-REAGENT MIXTURE AND METHOD FOR THE IMPLEMENTATION OF IT

Description

[0001] The present invention relates, in general, to the field of blood testing devices. More particularly, the invention relates to a microfluidic device for obtaining a plasma-reagent mixture and a method for implementing such a device in order to enable, in fine , the quantification of a blood biomarker of interest.

[0002] 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.

[0003] 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.

[0004] 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: to refine a prognosis by providing comprehensive information to characterize a disease (or the presence of a pathogen) in an individual and optimize their care; to tailor the treatment best suited to each patient. In this regard, depending on their metabolism, some people absorb medication particularly quickly. In this case, the medication can pass more rapidly into the bloodstream, its effects are amplified, and it is therefore necessary to reduce the usual prescribed doses; 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. The quantification of blood biomarkers thus appears as an essential tool for personalized medicine.

[0005] 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, making it 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.

[0006] To alleviate some of the aforementioned time-consuming steps, self-sampling blood collection kits are also available on the market. These kits can be used at home by any individual and require a smaller volume of blood, as disclosed in US patent applications 2019 / 0111421, US2014 / 0309557, and WO2014 / 172247A1. These kits offer devices for collecting, storing, or transferring a bodily fluid, in this case, blood. However, as with blood collection, such devices require the services of a laboratory for testing with specialized equipment and for the analysis of results by qualified personnel.

[0007] US patent application 2017 / 0001192 attempts to partially address these drawbacks by proposing a testing device that allows for the evaluation of biomarkers in bodily fluid without relying on external resources (laboratory, qualified personnel, etc.). However, such a device provides a qualitative result for a biomarker (presence or absence of the biomarker) but not a quantitative result for any biomarker. This solution therefore requires laboratory analysis to quantify the biomarker of interest and cannot identify proteins present in low abundance (on the order of micrograms to nanograms per milliliter and below) that may be essential markers.

[0008] US2014 / 0309557 and WO2014 / 172247A1 describe a device for collecting, storing, and transferring a blood sample. This device includes, prior to blood collection, an anticoagulant additive to ensure the safe transport of the blood sample to a laboratory for testing plasma derived from it. However, as with conventional blood collection procedures, separating the plasma from other blood components requires specific laboratory equipment, including a centrifuge, and qualified personnel.

[0009] Only a quantitative result from biomarkers allows, as previously indicated, for enhanced monitoring of a patient's health. Thus, the present invention aims to overcome the aforementioned drawbacks, in particular by proposing a microfluidic device for obtaining a homogeneous plasma-reagent mixture and a simplified implementation method for it, in order to provide in fine , of a direct and rapid quantification of a blood biomarker, at home, usable from a single drop of blood and which can be implemented by any user while ensuring reliability and reproducibility of results due to precise dosing / control of volumes, at all stages of the process, of the blood plasma and the reagent used.

[0010] In this respect, a first object of the invention relates to a microfluidic device for obtaining a homogeneous plasma-reagent mixture comprising: a blood collection module; a first capillary channel having a first end in fluidic connection with said collection module; a fluid storage reservoir in fluidic connection with said first capillary channel; a mixing chamber in fluidic connection with a second end of the first capillary channel arranged to passively cause a homogeneous mixing of fluids from said first capillary and having a flow outlet for said homogeneous mixture; a means of preventing any fluid backflow to the collection module.

[0011] To perform a test at home or on the go, and thus avoid the need to use third-party equipment and have a laboratory test performed by specialized personnel, such a microfluidic device for obtaining a homogeneous plasma-reagent mixture is arranged so that the plasma collection module includes: a semi-permeable membrane arranged to receive a quantity of blood and designed to separate, by gravity when said semi-permeable membrane is substantially horizontal, the constituents of the blood according to their sizes and thus trap said constituents other than blood plasma; a specific surface arranged between said semi-permeable membrane and the first end of the first capillary channel and having hydrophobic, hydrophilic and surface tension properties to extract the blood plasma from the semi-permeable membrane and circulate said blood plasma into said first capillary channel.

[0012] Furthermore, such a microfluidic device for obtaining a homogeneous plasma-reagent mixture is arranged so that: The first capillary channel has determined dimensions between the fluidic connection of said storage reservoir with the first capillary channel and said second end of said first capillary channel, to control the quantity of blood plasma when the first capillary channel is saturated with blood plasma; the fluid contained in the storage reservoir is a reagent intended to be mixed with blood plasma; said storage reservoir: ∘ is adapted to receive a volume of reagent greater than the sum of the volumes of fluids that the first capillary channel and the mixing chamber can contain; ∘ includes an actuator designed to cause a forced flow of said reagent into the first capillary channel resulting in a flow of a homogeneous plasma-reagent mixture from said outlet of the mixing chamber when said actuator is controlled after saturation of the first capillary channel with blood plasma.

[0013] In order to optimize the capillarity phenomenon and maximize the movement of blood plasma from the semi-permeable membrane to the first capillary channel, the first end of said first capillary channel can be positioned substantially in the center of said collection module.

[0014] To concentrate the blood deposited on the semi-permeable membrane and prevent any spread of blood outside its surface, the collection module of such a device may include a membrane holder arranged to concentrate the blood on said semi-permeable membrane.

[0015] Advantageously, the specific surface can be made of polymethyl methacrylate, thermoplastic polymer, polyacrylamide derivatives, polyurethane, poly[hydroxyethyl methacrylamide] or poly[ethylene glycol].

[0016] To optimize a passive and homogeneous mixing of blood plasma and circulating reagent in said first capillary channel, said mixing chamber may comprise a network of channels respectively arranged in zigzags, serpentines or chevrons to passively induce said homogeneous plasma-reagent mixing.

[0017] A second object of the invention consists of a method for implementing a microfluidic device for obtaining a homogeneous plasma-reagent mixture according to the invention. Such a method comprises the following steps: a step of depositing blood on the semi-permeable membrane of the plasma collection module, when said device is positioned so that the semi-permeable membrane is horizontal; a step of saturating the first capillary channel with blood plasma; a step, subsequent to said step of saturating the first capillary channel with blood plasma, of controlling the actuator of the storage tank causing the forced flow of a reagent, previously contained in said storage tank, into the first capillary channel beyond saturation of the mixing chamber; a step of collecting a homogeneous plasma-reagent mixture from the flow outlet of the latter.

[0018] As an example of advantageous implementation, the step of saturating the first capillary channel with blood plasma can consist of waiting, once the blood plasma flows into the first capillary channel, for a predetermined duration, depending on the size of the first capillary channel.

[0019] To perform an analysis of said plasma-reagent mixture, the step of collecting the homogeneous plasma-reagent mixture may consist of positioning a reagent strip downstream of the flow outlet of the mixing chamber so that said strip collects all or part of said homogeneous plasma-reagent mixture.

[0020] The description of the invention will now be continued by a detailed description of an example embodiment, given below by way of illustration but not limitation, with reference to the attached drawings, on which: There figure 1 shows a preferred example of the implementation of a microfluidic device for obtaining a plasma-reagent mixture according to the invention; The figure 2 shows a flowchart representing the steps in the process of implementing a device according to the invention; The figure 3 à 7 are schematic views of the device according to the invention illustrating different stages of implementation of said device according to the invention.

[0021] As a preliminary point, it is important to recall the definition of the following terms: Hydrophilicity is a term used to characterize a molecular property resulting from the existence of strong attractions or affinities between certain molecular groups and water. In other words, it is the affinity of a substance for water or the ability to be wetted by water without being dissolved; hydrophobicity is a term used to designate and characterize surfaces that seem to "repel water" or that water seems to have difficulty wetting, notably because water molecules are polar and have a preferential attraction to other polar molecules; surface tension / surface energy and contact angle: an energy per unit area is associated with an interface that separates two different media, the origin of which is the cohesive force between identical molecules.A representative example of such a quantity is that of a liquid droplet deposited on a surface / solid: such a droplet forms an angle, called the contact angle, which varies according to the surface tension of the surface / solid. Thus, if there is repulsion between the liquid and the solid, the droplet on the solid will tend to "group together" and take on a spherical shape, thus exhibiting a "high" contact angle. Conversely, if there is attraction between the liquid and the solid, the droplet on the solid will tend to spread out, thus exhibiting a "low" contact angle. In the case of a liquid such as water, if the contact angle is greater than zero degrees and less than ninety degrees, the water tends to spread out and wet the surface / solid: this is then called a wetting or hydrophilic surface. When the contact angle is approximately zero degrees, the wetting is complete.Thus, the greater the contact angle, the less wettable the support / solid is by water; capillarity is a property of fluids dependent on their surface tension, giving them the ability to rise or fall through a capillary tube / channel. The distance traveled by a liquid in the tube is greater the thinner the tube is; blood plasma is the liquid part of blood composed of more than ninety percent water. Thus, blood plasma is considered primarily hydrophilic.

[0022] A preferred example of a 100 microfluidic device for obtaining a homogeneous plasma-reagent mixture, according to the invention, is shown in the figure 1 The device 100 comprises at least one blood plasma collection module 110 in fluidic connection with a first end 120a of a capillary channel 120, itself in fluidic connection with a storage reservoir 130 of a reagent 103. For the purposes of the invention, "reagent" means any fluid that makes certain physicochemical parameters of the blood plasma, such as pH, optimal for the conformation of a protein to be quantified. Such a reagent can also be chosen to control the fluidic flow rate in the device and limit any non-specific interaction of the proteins of interest (biomarkers) with the semi-permeable membrane and the internal walls of the device. By way of non-limiting example, it may be composed of proteins such as BSA (" Bovine Serum Albumin » (according to Anglo-Saxon terminology), detergent (such as Tween 20), a saline solution (such as the " Phosphate Buffer Saline » according to Anglo-Saxon terminology) and / or an antibacterial solution (such as « Sodium Azide » (according to Anglo-Saxon terminology). Such a reagent is distinct from stabilizers or anticoagulants found in certain blood collection and transport devices such as those described for example in documents US2014 / 0309557 and WO2014 / 172247A1 mentioned previously, whose sole function is to allow the storage of blood samples until an analysis center and which do not need to be moved within said transport devices. The device 100 further comprises a means 140 for preventing any fluid backflow towards the collection module 110, positioned upstream of the fluid connection between the storage tank 130 and the capillary channel 120. The device 100 also comprises a mixing chamber 150 in fluid connection with a second end 120b of the capillary channel 120. The device 100 is implemented by the process 200, illustrated in the flowchart. figure 2 , in order to obtain a homogeneous mixture 104 of plasma-reagent from a minimum quantity of blood 101, more particularly blood plasma, on the order of ten to one hundred microliters, such a mixture 104 allowing, in fine , the quantification of a blood biomarker of interest using a test strip directly on site, i.e., for example, at home by the person who took the blood sample, usually the patient, or at the patient's bedside, in an ambulance, or even in a doctor's consulting room.

[0023] A step 210 of said process 200 consists of supplying blood plasma 102 to said collection module 110, which is in fluidic connection with the first end 120a of said capillary channel 120, considered as the upper part of said capillary channel 120, the second end 120b being considered as the lower part of said capillary channel 120 when said capillary channel 120 is oriented in space as indicated by the figure 1 Such a supply of blood plasma 102 can result in the deposition of blood in the collection module 110, when said collection module 110 is arranged to passively separate said blood plasma 102 from said blood, or consist of a direct deposition of plasma in said collection module. Thus, as illustrated in figure 3 , said blood plasma 102 can move automatically in the capillary channel 120 by capillarity, a phenomenon defined previously in this description, and thus flow vertically (from top to bottom according to the figure 1 ) along said channel 120. In a preferred but not limiting embodiment, in order to optimize such a capillary phenomenon and maximize the associated effect, it is preferable that the first end 120a of the capillary channel 120 be positioned substantially at the center of the lower surface of the collection module 110. Alternatively, said first end 120a of the capillary channel 120 may be positioned between the outer edge and the center of the lower surface of the collection module 110.

[0024] As mentioned previously, blood plasma 102 can advantageously be isolated, using said device 100 according to the invention, from one or more drops of blood 101 collected by the user. Such a drop 101 can be collected, for example, using a lancet device that the user applies to their fingertip or any other suitable device. Once the tip of the user's finger is pierced or pricked by the lancet, the user can then move their finger to the blood plasma collection module 110 to deposit the drop of blood 101, as illustrated in figure 1 In this respect, as illustrated in figure 3 In a preferred example, said module 110 includes a semi-permeable membrane 111 through which the collected blood 101 can pass or flow. Such a semi-permeable membrane 111, for example, of the well-known and commercially available Pall Vivid® brand, thus allows the blood components to be separated according to their sizes. The semi-permeable membrane 111 is arranged to receive a quantity of blood 101 and to separate, by gravity when the semi-permeable membrane 111 is substantially horizontal, the blood components according to their sizes, so that white blood cells, red blood cells, and other large-diameter components can be trapped in the membrane 111, while the blood plasma 102 can flow through the membrane. A filtration efficiency of sixty percent or more is considered.Thus, by gravity, when said membrane 111 is substantially horizontal, blood plasma 102 can be collected below said membrane 111.

[0025] Furthermore, in order to concentrate the blood 101 on said membrane 111 and to prevent the blood 101 from spreading outside the separation / filtration surface, delimited by the edges of said membrane 111, the collection module 110 may include a membrane holder 112 positioned so as to press and hold the edges of said membrane 111. However, a person skilled in the art should not limit themselves to such a membrane holder device 112 and may consider any other type of device enabling this function to be fulfilled.

[0026] Once the blood plasma 102 has been separated from the other blood components, it must be recovered to allow for the continuity of said plasma 102 within said device 100. To this end, said blood plasma 102 must be removed from the semi-permeable membrane 111 and also conveyed to the capillary channel 120. The invention is clearly distinct from the teachings of US patent 2012 / 0275955A1, which requires the presence of a vacuum chamber to create a flow and forcibly separate plasma from a blood sample through a membrane. Such forced filtration is likely to deform the membrane, or even to cause a known phenomenon of hemolysis, whereby red blood cells can break under the effect of said flow through the membrane, thus altering the plasma obtained. Indeed, the released cellular components (e.g.(potassium, lactate dehydrogenase, hemoglobin) during such destruction can alter the relevance and accuracy of subsequent protein quantification from said hemolyzed plasma. Contrary to such technical teaching from document US2012 / 0275955A1, as illustrated in . figure 1 The collection module 110 according to the invention may include a specific surface 113, positioned upstream of the fluidic connection of said plasma collection module 110 and the first end 120a of the capillary channel 120. Such a specific surface 113 allows, by gravity, the extraction of the plasma 102 from said semi-permeable membrane 111 and its circulation and progression by capillary action within the device 100 into the capillary channel 120. The invention thus prevents any risk of hemolysis or deformation of the semi-permeable membrane 111, preserving the blood plasma 102 thus isolated, and consequently maintains the relevance of any quantification relating to said blood plasma 102.

[0027] To enable the continuity of blood plasma 102 in the device 100 and not just the retention of said plasma 102, in other words to absorb the blood plasma 102 from said specific surface 113 and to passively set the latter in motion in the capillary channel 120, the latter must exhibit an optimized balance between hydrophobic and hydrophilic properties, properties specified previously in this description.

[0028] Indeed, because blood plasma 102 is primarily hydrophilic (composed of approximately ninety percent water) but also contains hydrophobic material, the specific surface 113 must have a suitable surface tension and be made of a hydrophilic material without being soluble in water. The specific surface 113 is thus arranged between the semipermeable membrane 111 and the first end 120a of the first capillary channel 120 and has specific hydrophobic, hydrophilic, and surface tension properties to extract blood plasma 102 from the semipermeable membrane 111 and to circulate or set in motion said blood plasma 102 within said first capillary channel 120.

[0029] Accordingly, the specific surface 113 may 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, those skilled in the art should not limit themselves to such a material and may consider any other type of material that provides similar properties or equivalent ones, such as, for example, derivatives of polyacrylamide, polyurethane, poly[hydroxyethyl methacrylamide], or polyethylene glycol.

[0030] As an alternative or in addition, 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, ...), Corona treatments or even chemical treatments (with sodium hydroxide, poly-vinyl alcohol, or hydroxypropylmethyl-cellulose, ...).

[0031] Once step 210 is completed, said step consisting of the deposit of blood 101 or blood plasma 102 into the plasma collection module 110 to obtain continuity or movement of said blood plasma 102 in the capillary channel 120, as illustrated in figure 2 A process 200 includes a step 220 of saturating the capillary channel 120 with blood plasma 102. This step 220 ensures a constant and controlled volume of blood plasma 102 within the capillary channel 120, thus perfectly dosing the amount of blood plasma in the capillary channel 120. To achieve this, the capillary channel 120 has specific dimensions, including a predefined length L, as illustrated in figure 4 The length L corresponds to the defined length between the fluidic connection of the storage reservoir 130 with the capillary channel 120 and the second end of the capillary channel 120. This length L thus allows, for a given cross-sectional diameter of the capillary channel 120, the determination and control of a quantity of blood plasma 102 when the capillary channel 120 is saturated with plasma 102. For example, for blood plasma volumes on the order of ten to one hundred microliters, the capillary channel 120 may 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 may 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 will be preferred as a preferred material because functionalizing their surface (particularly to increase hydrophilic properties and / or improve capillarity) is easier than with other materials. Furthermore, such a capillary channel 120 can be integrated into the device 100 as a separate component. Alternatively, however, if the device 100 includes 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 mixing chamber 140, such components could be created directly by molding or additive manufacturing of said body, or by removing material from it using laser technology or machining.

[0032] Furthermore, to promote saturation of the capillary channel 120 with blood plasma 102, the volume of the capillary channel 120 can be sized to be less than the volume of blood plasma 102 contained in the collection module 110. Alternatively, the step 220 of saturating the capillary channel 120 with blood plasma 102 can consist of waiting, once the blood plasma 102 flows along the capillary channel 120, for a predetermined duration, defined according to the sizing of said capillary channel 120. However, a person skilled in the art should not limit the invention to such a step and may consider any other way of implementing the saturation step 220, such as, for example, the appearance of a colored indicator when the capillary channel 120 is saturated with blood plasma 102 or the use of information provided by a sensor, for example an optical sensor, positioned in the immediate vicinity of the second end 120b of said channel 120.

[0033] 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.

[0034] In another preferred embodiment illustrated in figure 5 , such a means 140 of preventing any fluidic return may consist of a screw whose stroke causes a "pinching" of said capillary channel 120. Such a screw can thus be actuated, once the saturation of the capillary channel 120 with blood plasma 102 has been obtained, in order to put pressure on the capillary channel 120, pinch it and / or close it, thus allowing to stop any flow of blood plasma 102 towards the collection module 110. The 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 the level of its first end 120a.

[0035] 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 operated manually by the user once the saturation step 220 has been completed, 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 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.

[0036] 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.

[0037] As illustrated in figure 2 and in figure 5 , it follows (in parallel or subsequent to the actuation of the means 140 for preventing any fluid backflow when such actuation is required) a step 230 to cause the forced flow of a reagent 103, previously contained in the storage tank 130 of a reagent 103, into the capillary channel 120. As such, such a storage tank 130 can be arranged in the form of a flexible pouch intended to contain a fluid, commonly called by the Anglo-Saxon term " blister pouch ", fluidly connected to the capillary channel 120 by means of, for example, a capillary tube forming a T-junction 120c with the capillary channel 120. Thus, in such an embodiment, the reagent 103 is contained in said flexible pouch, and the forced flow of said reagent 103 into said channel 120 can be caused by mechanical compression performed by the user of said device 100. In other words, the user himself presses on the flexible pouch to release its contents (the reagent 103) into the capillary channel 120. However, a person skilled in the art should not limit himself to the shape and / or design of such a fluid storage reservoir 130. Any other type of storage reservoir, such as, for example, a user-operated syringe, could be used in place of the flexible pouch.Alternatively, such storage reservoirs 130 (flexible bag, syringe, or any other type) may include an actuator 131 arranged to generate a piston displacement or compression, thereby forcing the reagent 103 into the capillary channel 120. Step 230 would therefore consist of controlling such an actuator 131 either manually (by the user) or automatically, similar to the electrically controlled valve mentioned previously, to prevent any fluid backflow to the collection module 110. The processing unit, which may produce a closing signal for said valve, would also generate a control signal for such an actuator 131.

[0038] Thus, as illustrated in figure 5 and in figure 6 Due to the saturation of the capillary channel 120 with blood plasma 120, the forced flow of reagent 103 within said channel 120 causes the flow of said blood plasma 102 and reagent 103 contained in said capillary channel 120 into said mixing chamber 150, which is in fluidic connection with the second end 120b of said channel 120 (i.e., the lower part of said channel 120 in the illustrated embodiment). In other words, such a forced flow of reagent 130 acts as a "fluidic piston" to move blood plasma 102 contained in the saturated capillary channel 120 to said mixing chamber 150, within which a homogeneous mixture 104 of plasma 102 and reagent 130 will be obtained. To promote and facilitate the passive homogenization of the plasma-reagent mixture 104, said mixing chamber 150 may include a network of channels 151 arranged for example in zigzags, serpentines, or chevrons.A person skilled in the art should not limit themselves to the design of the mixing chamber 150 that allows for a homogeneous plasma-reactive fluidic mixture 104, as any other type of design or structure could be considered, such as, for example, a micropillar structure. Furthermore, such a mixing chamber 150 includes an outlet 152 through which the homogeneous and constant plasma-reactive mixture 104 can flow. This outlet 152 thus corresponds to an ejection / discharge outlet for the plasma-reactive mixture 104 to the outside of the device 100.

[0039] Furthermore, said microfluidic device 100 for obtaining a plasma-reagent mixture according to the invention is dimensioned so that the volume of said storage tank 130 is greater than the sum of the volumes of said capillary channel 120 and of said mixing chamber 150. By way of illustration but not limitation, such a mixing chamber 150 could have a volume of sixty microliters (which may correspond to dimensions of four millimeters in diameter by five millimeters in length) to two hundred and fifty microliters (which may correspond to dimensions of five millimeters in diameter by thirteen millimeters in length) and the storage tank 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 continue until said chamber 150 is saturated with the plasma-reagent mixture 104, thereby allowing the flow of a constant plasma-reagent mixture 104 via the outlet 152 of the mixing chamber 150. A device 100 according to the invention is thus clearly distinguished from the blood transport devices disclosed by documents US2014 / 0309557 and WO2014 / 172247A1 by their structures and dimensions, taking into account their storage and transport function as well as the nature of the fluids intended to circulate within them. Indeed, known transport devices are arranged so that the blood collected and stored together with a stabilizer or anticoagulant remains passively within them during transport between the collection site and the analysis center.Only after the plasma has been separated by centrifugal force using third-party equipment can a plasma sample be extracted from the transport device by means of an actuator designed to facilitate the extraction of the plasma contained within, via a previously sealed outlet, for analysis. Without the prior action of a centrifuge, the actuator in known transport devices would only allow the extraction of blood stored in the blood sample transfer device.

[0040] Thanks to the innovative arrangement of a device 100 according to the invention, once the homogeneous and constant plasma-reactive mixture 104 flows from the outlet 152 of the mixing chamber 150, said method 200 for implementing such a microfluidic device 100 for obtaining a homogeneous plasma-reactive mixture according to the invention comprises a final step 240 for collecting said mixture 104. In a preferred embodiment of the invention, as illustrated in figure 7 , such a step 240 may consist of positioning a reactive strip 160 such as, for example, a lateral flow immunoassay strip, also known by the acronym "LFI" meaning in Anglo-Saxon " Lateral Flow Immunoassay ", downstream of the outlet 152 of said mixing chamber 150. Said mixture 104 can thus be deposited on said reactive strip 160.

[0041] Such a 160-strip test strip can be used directly by the user to quantify the blood biomarker of interest by placing said strip in an optical reader, allowing immediate reading and display of the quantified result. Thus, an individual wishing to enhance their health monitoring can use, from their home or while traveling, a blood biomarker quantification system comprising a microfluidic device for obtaining a homogeneous plasma-reagent mixture according to the invention, a 160-strip test strip, 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 suitable software application or computer program allowing, for example, the recording of results and / or the creation of a medical dashboard or a history of analyses performed.

[0042] 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. In particular, in the preferred example described above, the device 100 includes a capillary channel. However, to increase the capillary force exerted on the plasma present in the collection module 110, a device 100 may include several capillary channels (two, three, or even more) opening, on the one hand, into the collection module 110 and, on the other hand, into the mixing chamber 150, possibly via a collecting "mother" channel. Furthermore, reference has been made herein to a capillary channel that facilitates industrial use because it is non-deformable. However, a capillary tube could, alternatively, be used.

Claims

1. A microfluidic device for obtaining a homogeneous plasma-reagent mixture (100) comprising: - a collection module (110) for blood (101); - a first capillary channel (120) having a first end (120a) in fluid connection with said collection module (110); - a fluid storage reservoir (130) in fluid connection with said first capillary channel (120); - a mixing chamber (150) in fluid connection with a second end (120b) of the first capillary channel (120) arranged to passively cause a homogeneous mixture (104) of fluids from said first capillary and having an outlet (152) for flow of said homogeneous mixture; - means (140) for preventing any fluidic return to the collection module (110); - the first capillary channel (120) has determined dimensions (L) between the fluid connection of said storage reservoir (130) with the first capillary channel (120) and said second end (120b) of said first capillary channel (120), to control the amount of blood plasma (102) when the first capillary channel (120) is saturated with blood plasma (102); - the fluid contained in the storage reservoir is a reagent (103) intended to be mixed with blood plasma; - said storage reservoir (130): ∘ is suitable for receiving a reagent volume (130) greater than the sum of the fluid volumes that can be contained in the first capillary channel (120) and the mixing chamber (150); o includes an actuator (131) designed to cause a forced flow of said reagent (103) into the first capillary channel (120) resulting in a flow of a homogeneous plasma-reagent mixture (104) through said flow outlet (152) of the mixing chamber (150) when said actuator is controlled after saturation of the first capillary channel with blood plasma (102) characterized in that: - the collection module (110) includes: a semi-permeable membrane (111) arranged to receive an amount of blood (101) and designed to separate, by gravity when said semi-permeable membrane (111) is substantially horizontal, the constituents of the blood according to their sizes and thus trap said constituents other than the blood plasma (102); a specific surface (113) arranged between said semi-permeable membrane (111) and the first end (120a) of the first capillary channel (120) and having hydrophobic, hydrophilic and surface tension properties for extracting the blood plasma (102) from the semi-permeable membrane (111) and circulating said blood plasma (102) in said first capillary channel (120).

2. The microfluidic device for obtaining a homogeneous plasma-reagent mixture (100) according to the preceding claim, for which the first end (120a) of the first capillary channel (120) is positioned substantially at the center of said plasma collection module (110).

3. The microfluidic device for obtaining a homogeneous plasma-reagent mixture (100) according to any of the preceding claims, for which the collection module (110) includes a membrane holder (112) arranged to concentrate the blood (101) on said semi-permeable membrane (111).

4. The microfluidic device for obtaining a homogeneous plasma-reagent mixture (100) according to any of the preceding claims, for which the specific surface (113) is made of polymethyl methacrylate, a thermoplastic polymer, polyacrylamide, polyurethane, poly[hydroxyethyl methacrylamide] or poly[ethylene glycol] derivatives.

5. The microfluidic device for obtaining a homogeneous plasma-reagent mixture (100) according to any of the preceding claims, for which said mixing chamber (150) includes an array of channels (151) respectively arranged in zigzag, serpentine or chevron patterns to passively cause said homogeneous plasma-reagent mixture (104).

6. A method (200) of operating a microfluidic device for obtaining a homogeneous plasma-reagent mixture (100) arranged according to any of the preceding claims, said method including: - a step (210) of depositing blood (101) or blood plasma (102) on the semi-permeable membrane (111) of the plasma collection module (110), when said device is positioned so that the semi-permeable membrane (111) is horizontal; - a step (220) of saturating the first capillary channel (120) with blood plasma (102); - a step (230), subsequent to said step of saturating the first capillary channel (120) with blood plasma (102), of controlling the actuator (131) of the storage reservoir (130) causing the forced flow of a reagent (103) previously contained in said storage reservoir (130) into the first capillary channel (120) beyond a saturation of the mixing chamber (150); - a step (240) of collecting a homogeneous plasma-reagent mixture (104) from the flow outlet (152) of the mixing chamber (150).

7. The method (200) of operating a microfluidic device for obtaining a homogeneous plasma-reagent mixture (100) according to the preceding claim, for which the step (220) of saturating the first capillary channel (120) with blood plasma (102) consists of waiting, once the blood plasma (102) has flowed into the first capillary channel (120), for a predetermined period of time, depending on the dimensions of the first capillary channel (120).

8. The method (200) of operating a microfluidic device for obtaining a homogeneous plasma-reagent mixture (100) according to one of claims 6 and 7, for which the step (240) of collecting the homogeneous plasma-reagent mixture (104) consists of positioning a reagent strip (160) downstream of the outlet (152) of the mixing chamber (150) so that said strip (160) collects all or part of said homogeneous plasma-reagent mixture (104).