WO2025078446A1

WO2025078446A1 - Microfluidic device and method thereof for rapid assays in samples

Info

Publication number: WO2025078446A1
Application number: PCT/EP2024/078419
Authority: WO
Inventors: Carl Olsson; Janosch HAUSER; Federico RIBET; Martin Schalling; Lena BACKLUND; Niclas ROXHED
Original assignee: Individual
Current assignee: Individual
Priority date: 2023-10-09
Filing date: 2024-10-09
Publication date: 2025-04-17
Anticipated expiration: 2026-04-09

Abstract

A microfluidic device (100) for measuring a component in a liquid sample (130). The microfluidic device (100) comprises an inlet port (102) for the liquid sample (130). The inlet port (102) comprises a capillary driven sample separation means (104) configured to separate a substantially particle-free liquid filtrate (132) from the liquid sample (130). The microfluidic device (100) comprises further a capillary channel (106) connecting the inlet port (102) and a read-out chamber (108), and configured to meter a pre-determined volume of the liquid filtrate (132). A reagent storage means (110) of the microfluidic device (100) is connected to the capillary channel (106). Th reagent storage means (110) comprises a reagent (112) and an injection means (114) configured to inject the reagent (112), wherein injecting the reagent (112) in the capillary channel (106) between the reagent storage means and the read-out chamber (108) feeds the pre- determined volume of the liquid filtrate (132) into the read-out chamber (108) to be mixed and react with the injected reagent (112) in the read-out chamber (108). The microfluidic device (100) also comprises a de-bubbling means (140) configured to remove bubbles in the reagent (112) before the reagent (112) reaches the capillary channel (106), the de-bubbling means comprising a pressure buffer (116) configured to stabilize a pressure of the reagent (112) downstream of the reagent storage means (110). The microfluidic device facilitates improved monitoring of components such as ions or psychotherapeutic drugs with precise and critical levels in the body.

Description

MICROFLUIDIC DEVICE AND METHOD THEREOF FOR RAPID ASSAYS IN SAMPLES

Technical field

The present invention generally relates to analysis of samples, especially it relates to a microfluidic device for determining levels of medical drugs in body fluids.

Background

Lithium (Li+) is one of the most effective mood stabilizers used to treat bipolar disorder, a prevalent disorder afflicting 1-2% of the population. However, Li+ treatment is problematic due to a small therapeutic window and the risk of severe adverse effects at high Li+ blood levels, necessitating the need for tailored doses to suit each patient. Li+ monitoring is essential for all patients undergoing treatment and is accomplished by frequent blood tests at the start of treatment with regular followups three times a year.

Summary

It would be desirable to improve performance for measuring components in liquids. It is an object of this disclosure to address at least one of the issues outlined above.

Further, there is an object to devise an arrangement and a method that facilitates increased frequency and improved routines for measurements. These objects may be met by an arrangement and a method according to the attached independent claims.

According to a first aspect a microfluidic device for measuring a component in a liquid sample is provided. The microfluidic device comprises an inlet port for the liquid sample. The inlet port comprises a capillary driven sample separation means configured to separate a substantially particle-free liquid filtrate from the liquid sample. The microfluidic device comprises further a capillary channel connecting the inlet port and a read-out chamber, and configured to meter a pre-determined volume of the liquid filtrate. A reagent storage means of the microfluidic device is connected to the capillary channel. The reagent storage means comprises a reagent and an injection means configured to inject the reagent, wherein injecting the reagent in the capillary channel between the reagent storage means and the read-out chamber feeds the pre-determined volume of the liquid filtrate into the read-out chamber to be mixed and react with the injected reagent in the read-out chamber. The microfluidic device also comprises a de-bubbling means configured to remove bubbles in the reagent before the reagent reaches the capillary channel, the de-bubbling means comprising a pressure buffer configured to stabilize a pressure of the reagent downstream of the reagent storage means.

The microfluidic device may be adapted to measurements on body liquid samples comprising blood and the liquid filtrate may comprise at least one of blood plasma and serum. The microfluidic device may further be adapted to measure components in other body liquids, e.g. saliva, or urine.

The reagent storage means may be configured to release the reagent when being pressed and punctured. The reagent storage means may comprise an oxygen barrier layer such as a metal-coated foil. The reagent storage means may comprise a reservoir, a blister, a container, etc.

The reagent may comprise one or more components, e.g. any of a colorimetric substance, and a fluorescent substance, or a suitable combination thereof.

The colorimetric substance may be adapted to detect at least one of medical drugs, e.g. psychotherapeutic drugs, and metallic ions. The ions may comprise any of: Lithium, Sodium, Potassium, Rubidium, Cesium, Francium, Beryllium, Magnesium, Calcium, Strontium, Barium, Radium, Aluminium, Gallium, Indium, Tin, Thallium, Lead, Bismuth, Scandium, Titanium, Vanadium, Chromium, Manganese, Iron, Cobalt, Nickel, Copper, Zinc, Yttrium, Zirconium, Niobium, Molybdenum, Technetium, Ruthenium, Rhodium, Palladium, Silver, Cadmium, Lanthanum, Hafnium, Tantalum, Tungsten, Rhenium, Osmium, Iridium, Platinum, Gold, and Mercury.

The psychotherapeutic drugs may comprise any of: chlorpromazine (Thorazine), fluphenazine (Prolixin), haloperidol (Haldol), loxapine (Loxitane), thiothixene (Navane), clozapien (Clorazil), olanzapine (Zyprexa), quetiapine (Seroquel), risperidone (Risperdal), armodafinil (Nuvigil), atomoxetine (Stratera), dexmethylphenidate (Focalin), dextroamphetamine (Dexedrine), guanfacine (Intuniv), methylphenidate (Ritalin, Concerta), modafinil (Provigil).

The colorimetric substance may be a porphyrin-based chemical, preferably phenylporphyrin, and more preferably a tetraphenylporphyrin.

The reagent may be provided in dry form, or be suspended in a liquid, or a gel. The reagent may further be combined with at least one activator reagent.

The de-bubbling means of the microfluidic device may comprise a bubble-trap configured to remove bubbles from the reagent. The bubble-trap may comprise a compartment configured to store volumes 1 -500 pL of the reagent, the compartment’s exits being provided with respective flow restrictors. The flow restrictors may comprise a combination of paper flow restrictors, mesh flow restrictors, geometric flow restrictors, and vents.

The pressure buffer of the microfluidic device may comprise comprises a dead-end microfluidic channel configured to hold volumes from 1 -500 pL and having a height between 10-2000 pm.

The readout chamber of the microfluidic device be configured to be used in conjunction with a separate read-out analysis apparatus. Alternatively, the readout chamber may facilitate manual readout by adapting the reagent, therefore. Both variants achieve respective benefits, an analysis of an apparatus may achieve improved medical security, when a manual analysis may be less complex.

According to a second aspect, a system for analysing a component in a liquid sample is provided. The system comprises the microfluidic device according to the above defined first aspect and a separate read-out analysis apparatus configured for optical readout, either vertically, diagonally, and/or horizontally. The optical readout method may be at least one of colorimetric, and fluorescent.

According to a third aspect, a method of measuring a component in a liquid sample is provided. The method comprises the following actions at a microfluidic device: by an inlet port, providing a liquid sample; by a capillary driven sample separation means, separating a substantially particle-free liquid filtrate from the liquid sample; by a capillary channel connecting the inlet port and a read-out chamber, metering a pre-determined volume of the liquid filtrate. Further, the method comprises also: by a reagent storage means comprising a reagent and an injection means, injecting the reagent in the capillary channel after having been de-bubbled by a de-bubbling means, whereby the pre-determined volume of the liquid filtrate is fed into the read-out chamber to be mixed and react with the injected reagent in the read-out chamber; detecting a color, light absorption, or light intensity of the mixed reagent and the liquid filtrate in the read-out chamber; and determining a concentration of the component based on the detected color, light absorption, or light intensity.

Furthermore, in the method, the liquid sample may be 1-100 pL blood, and the substantially particle-free filtrate may be blood plasma. The reagent may comprise a colorimetric substance or a fluorescent substance for detecting at least one of: medical drugs, psychotherapeutic drugs, and metallic ions. The reagent may be configured to detect ions from a set comprising: Lithium, Sodium, Potassium, Rubidium, Cesium, Francium, Beryllium, Magnesium, Calcium, Strontium, Barium, Radium, Aluminium, Gallium, Indium, Tin, Thallium, Lead, Bismuth, Scandium, Titanium, Vanadium, Chromium, Manganese, Iron, Cobalt, Nickel, Copper, Zinc, Yttrium, Zirconium, Niobium, Molybdenum, Technetium, Ruthenium, Rhodium, Palladium, Silver, Cadmium, Lanthanum, Hafnium, Tantalum, Tungsten, Rhenium, Osmium, Iridium, Platinum, Gold, and, Mercury. The reagent may alternatively be adapted to detect a medical drug, preferably a psychotherapeutic drug from a set comprising: chlorpromazine (Thorazine), fluphenazine (Prolixin), haloperidol (Haldol), loxapine (Loxitane), thiothixene (Navane), clozapien (Clorazil), olanzapine (Zyprexa), quetiapine (Seroquel), risperidone (Risperdal), armodafinil (Nuvigil), atomoxetine (Stratera), dexmethylphenidate (Focalin), dextroamphetamine (Dexedrine), guanfacine (Intuniv), methylphenidate (Ritalin, Concerta), modafinil (Provigil).

Further for the method, the reagent may be a colorimetric agent, such as a porphyrin-based chemical, preferably phenylporphyrin, and more preferably a tetraphenylporphyrin. The reagent may be provided in dry form or be suspended in a liquid or in a gel. The reagent may further be combined with an activator reagent. At least one of the actions of reading the color and determining the concentration may be performed by a separate read-out analysis apparatus configured to detect any of the color, light absorption, and light intensity, and determining the concentration based on the detected color, light absorption, or light intensity. By developing a microfluidic device as defined by the inventive concept of this disclosure, monitoring of components such as ions or psychotherapeutic drugs with precise and critical levels in the body may be facilitated, as a more frequent testing is enabled without direct access to medical staff. Instead, the patient may himself/herself screen and monitor the levels and contact the medical staff in case of concerns or worries.

Brief description of the drawings

The above, as well as additional objects, features, and advantages of the present inventive concept, will be better understood through the following illustrative and non-limiting detailed description, with reference to the appended drawings. In the drawings like reference numerals will be used for like elements unless stated otherwise.

Fig. 1 shows a schematic perspective view of a microfluidic device, according to an exemplifying embodiment.

Fig. 2 shows schematic cross-sectional views of a working principle for a microfluidic device, according to an exemplifying embodiment.

Fig. 3 shows a schematic view of a microfluidic device, according to an exemplifying embodiment.

Fig. 4a-b shows schematic cross-sectional views of different material layers of a microfluidic device, according to an exemplifying embodiment.

Fig. 5 show schematic block diagram of different parts of a microfluidic device, according to an exemplifying embodiment.

Fig. 6 shows a schematic graph of absorbance spectrums for a microfluidic device, according to an exemplifying embodiment.

Fig. 7 shows a schematic view of a microfluidic device, according to an exemplifying embodiment.

Fig. 8 shows a schematic graph of results from experiments with a microfluidic device, according to an exemplifying embodiment. Detailed description

The lack of more frequent testing is one of the reasons Li+ is not used as often as it should since infrastructure for continuous testing, and follow-ups are needed. This work presents a prototype device that allows patients to perform these tests at home, like a diabetic patient monitors their glucose levels. We developed a simple-to- use and disposable point-of-care on-chip colorimetric assay for Li+ concentration measurements from finger-prick blood using a colorimetric assay.

With reference to Figure 1 , which is a schematic concept view, an arrangement for measuring a component in a blood sample will now be described according to an exemplifying embodiment.

A microfluidic device 100 comprises an inlet port 102 for receiving a blood sample, a reagent storage means 110 for storing a reagent, and a read-out chamber 108 for reading a concentration of a component in the blood sample. In figure 1 , three enlarged partial views show that a body liquid sample in form of a drop of blood 130 is received at the inlet port 102. A capillary driven sample separation means 104 separates a cell-free liquid filtrate, i.e. blood plasma from the drop(s) of blood. As will be later exemplified the sample separation means 104 is capillary driven by being implemented as a thin capillary channel between the inlet port 102 and the read-out chamber 108. After a time period, in this embodiment 15 minutes, when the capillary channel is filled with blood plasma, the reagent storage means 110 in form of a blister is pressed and punctured such thus a reagent in the blister 110 is injected into the capillary channel. The amount of reagent in the blister 110 ensures that the blood plasma in the capillary channel is forced into the read-out chamber 108 together with an appropriate amount of the reagent to be mixed therein. After a second period of time, in this embodiment 10 minutes, the reagent and the blood sample are reliably mixed such that the concentration of the component in the blood sample may be determined with high precision by reading a color of the mixture in the read-out chamber 108.

The concept will be further described below in conjunction with further exemplifying embodiments and with reference to the other figures of this disclosure. As will be understood, the inventive concept is not limited only to blood analysis, also other body liquids may be analysed and by selecting appropriate reagents the device and method of this disclosure may be adapted to different medical drugs, e.g. psychotherapeutic drugs, or ions in the human body.

The above described concept may further be adapted to measurements of components in liquids in general. Any appropriate liquid samples may then be filtrated and instead of specifically filtering out cells, the capillary driven sample separation means may be configured to filter out any particles present in the appropriate liquids. Further, the exemplifying embodiments of this disclosure may be adapted to general measurement of components in liquids without deviating from the inventive concept.

Design of the device & Experimental

Building on knowledge from plasma extraction from finger-prick blood using microfluidic chips, the applicant developed a disposable and simple-to-use fingerprick microfluidic device for point-of-care measurements using a single-reagent colorimetric assay compatible with a standard plate reader.

With reference to Figure 2, which is a schematic series of views, a sequence of operations performed within a microfluidic device 100 will now be described in accordance with one exemplifying embodiment. Adding whole blood 130 (Step 1 ) initiates the autonomous blood plasma separation and metering of 2.5 pL plasma 132, i.e. blood plasma, in a capillary channel 106 connecting the inlet port 102 and the read-out chamber 108 (steps 2 and 3). The inlet port 102 comprises a capillary driven sample separation means 104, through which the blood plasma 132 passes as a substantially cell-free liquid filtrate. In the figure the appropriate amount, here 2.5 pL is the volume of blood plasma 132 in the capillary channel at the right of the conjunction and left from the read-out chamber 108. After waiting for 15 min, 50 pL of a chemical reagent (Espa Li II, Nipro) 112 is introduced by pressing on the blister pouch (step 4) shown in Figure 3 and referred to as reagent storage means 110, pushing the precisely measured amount of plasma sample 132 into the readout chamber 108. The reagent 112 is mixed with plasma (blood plasma) 132 during filling of the readout chamber 108 (step 5). After the readout chamber 108 is filled, the device 100 is left for 10 min before analysis in a conventional plate reader.

Figure 3 shows a schematic image of the microfluidic device 100 with the blister pouch 110, sampling area, i.e. inlet port 102, and readout chamber 108 marked, in accordance with one exemplifying embodiment. The device is 50 x 27 x 3.5 mm³ (i.e. mm, se comment below) fabricated by structuring laminated hydrophilic sheets, plastic sheets, and adhesive tapes as previously reported to ensure low-cost fabrication, with incorporated chromatography paper, blood filtration membrane 104, and a 150 pL blister pouch 110 with colorimetric reagent. It is understood that the measurement unit above was intended to be mm, not mm³, as it obviously relates to length units not a volume. As indicated in the figures the numbers obviously relate to a length of 50 mm a width of 27 mm and a thickness of 3.5 mm. At the right in Figure 3, four different read-outs are illustrated, first for a 0 mM concentration of Li⁺-ions in a blood sample, then for a 0.3 mM concentration, a 0.6 mM concentration and a 0.9 mM concentration, respectively. For the 0 mM the read-out is lighter, and the colors corresponding to the higher concentrations appears a bit darker for each step of increased concentrations.

A detailed example of an appropriate design of the microfluidic device 100 will be described below in conjunction with an embodiment example and in conjunction with Figures4a-c.

The Figures 4a-c are schematic cross-sectional views of different parties of a microfluidic device, according to exemplifying embodiments.

Figure 4a illustrates the plasma separation and metering part, figure 4b illustrates a bubble remover and figure 4c illustrate flow restrictors.

With reference to Figure 4a, plasma filtration starts by applying 50 - 100 pL whole blood to the sample-inlet area, also referred to as inlet port 102. The sample inlet area consists of a blood plasma filter 104, separating the red blood cells from the blood plasma. The filter 104 is attached to a hydrophilic sheet to facilitate autonomous filtration. When the plasma has been filtered out, it enters the inlet (a), moving through the flow restrictor (b), filling the metering channel (c), also referred to as capillary channel 106, before being stopped by a geometrical formation stop valve (d). The flow restrictor (b) prevents backflow into the inlet (a).

With reference to Figure 4b, the reagent is introduced by pressing on top of the blister, also referred to as 110 when the metering channel (c) has been filled with

2.5 pL. The reagent enters the microfluidic device 100 through a second inlet (f). The needle 114 is designed to let as much air out as possible under the blister 110 to reduce the bubble formation by surfactants in the reagent. However, in this embodiment the reagent further passes through a de-bubbling means 140 to remove any remaining bubbles. The de-bubbling means 140 consists of a pressure buffer 116 (g) and a reservoir 118 (h) connected to two flow restrictors (k, i), one for venting out air with a high resistance (k) and one with a lower resistance for slowing down the flow and blocking bubbles (i) from continuing to the metering channel 106 (c). The reservoir 118 (h) fills up with reagent, and when bubbles enter the reservoir 118, the paper in the flow restrictor (i) slows down the reagent flow and gives time for the bubbles to rise, leaving a bubble-free flow of reagent at the bottom of the reservoir 118 (h). The paper in the flow restrictor (i) also acts as a mesh filter, blocking bubbles from moving past the flow restrictor (i) and into the metering channel 106 (c).

The channel in between the flow restrictor (i) and metering channel 106 (c) is vented through a high resistance flow restrictor (m) to not trap air and ensure a clean flow to the metering channel (c). The reagent pushes the sample through the metering channel (c) and into the readout chamber 108 (e), where the volume is geometry defined to 1 :20 v/v ratio between the sample and reagent. The readout chamber 108 (e) is vented through a transparent porous membrane.

The pressure buffer 116 (g) is a dead-end microfluidic channel with a small flow restrictor at the inlet and no vent. It prevents backflow by storing reagents under pressure caused by the pushing force acting upon the blister 110 and equalizing when the force is removed.

The two high-resistance flow restrictors (k and m) redirect the reagent flow away from air vents. There will still be a low flow through the flow restrictors; therefore, they will be vented into a reservoir before the final vent to trap the excess reagent and avoid any reagent leaking out of the device. An appropriate implementation of the flow restrictors (k and m) and the reservoir is illustrated in Figure 4c.

Figure 5 is a schematic overview of the microfluidic device 100, according to some exemplifying embodiments. The same reference number have been used where appropriate to facilitate the understanding.

The reagent source 110 corresponds to the reagent storage means 110 and may be implemented as the above described blister. The pressure buffer 116 is configured to stabilize the pressure of the reagent. The de-bubbling means 140 is configured to remove bubbles arising in the reagent before being injected into the metering channel 106, which is also referred to as capillary channel above. The debubbling means is configured to let bubbles be ventilated from the reagent. When the reagent is injected into the metering channel 106, a precise metered amount of blood plasma 132 therein is forced into the readout chamber 108 to be mixed with the reagent. In this embodiment the readout chamber 108 is provided with ventilation to vent away bubbles arising when the reagent is mixed with the blood plasma 132.

Results and Discussion

We successfully demonstrated Li+ measurement using 60 pL spiked whole blood (Het 45%) with an effective standard deviation of less than 0.08 mM (Fig.8a). Results indicate a linear relationship between 0 mM and 0.9 mM with an R2 of 0.94 as shown Figure 8b. Absorbance measurements were carried out at 550 nm and 490 nm (Fig.6 upper graph) using a plate reader (Fig.7). Absorbance measurements have also been carried out for alternative wavelengths with promising results. For instance, the lower graph of Fig. 6 shows the absorbance when measurements were carried out for 546 nm and 600 nm.

Conclusion

This paper demonstrates a functional point-of-care prototype device able to precisely meter and mix a sample and reagent for on-chip concentration determination of Li+ in blood using a colorimetric assay. This platform is compatible with any single-reagent assay. The presented device could help make Li+ treatments safer and available to more patients by increasing the frequency of measurements and decreasing the reliance on laboratories offering Li+ tests.

The present invention generally relates to a microfluidic device for measuring therapeutic drugs in blood or metallic ion levels from a small blood sample. The device prepares and measures a sample and mixes it with a pre-determined amount of a liquid reagent after removing bubbles from the reagent and uses a colorimetric readout.

Claims

1. A microfluidic device (100) for measuring a component in a liquid sample (130), the microfluidic device (100) comprising:

• an inlet port (102) for the liquid sample (130) comprising a capillary driven sample separation means (104) configured to separate a substantially particle-free liquid filtrate (132) from the liquid sample (130),

• a capillary channel (106) connecting the inlet port (102) and a read-out chamber (108), and configured to meter a pre-determined volume of the liquid filtrate (132),

• a reagent storage means (110) connected to the capillary channel (106), the reagent storage means (110) comprising a reagent (112) and an injection means (114) configured to inject the reagent (112) , wherein injecting the reagent (112) in the capillary channel (106) between the reagent storage means and the read-out chamber (108) feeds the pre-determined volume of the liquid filtrate (132) into the read-out chamber (108) to be mixed and react with the injected reagent (112) in the read-out chamber (108), and

• a de-bubbling means (140) configured to remove bubbles in the reagent (112) before the reagent (112) reaches the capillary channel (106), the de-bubbling means comprising a pressure buffer (116) configured to stabilize a pressure of the reagent (112) downstream of the reagent storage means (110).

2. The microfluidic device (100) according to claim 1, wherein the liquid sample (130) comprises blood and the liquid filtrate (132) comprises at least one of plasma and serum.

3. The microfluidic device (100) according to any of the previous claims, wherein the reagent storage means (110) is configured to release the reagent (112) when being pressed and punctured.

4. The microfluidic device (100) according to any of the previous claims, wherein the reagent storage means (110) comprises an oxygen barrier layer.

5. The microfluidic device (100) according to claim 4, wherein the oxygen barrier layer comprises a metal-coated foil.

6. The microfluidic device (100) according to any of the previous claims, wherein the reagent storage means (110) comprises any of a reservoir, a blister, and a container.

7. The microfluidic device (100) according to any of the previous claims, wherein the reagent (112) comprises one or more components.

8. The microfluidic device (100) according to any of the previous claims, wherein the reagent (112) comprises at least one of a colorimetric substance, and a fluorescent substance.

9. The microfluidic device (100) according to any of the previous claims, wherein the reagent (112) comprises a colorimetric substance for detecting at least one of medical drugs, psychotherapeutic drugs, and metallic ions.

10. The microfluidic device (100) according to claim 9, wherein the reagent (112) is configured to detect an ion.

11. The microfluidic device according to claim 10, wherein the ion comprises one of Lithium, Sodium, Potassium, Rubidium, Cesium, Francium, Beryllium, Magnesium, Calcium, Strontium, Barium, Radium, Aluminium, Gallium, Indium, Tin, Thallium, Lead, Bismuth, Scandium, Titanium, Vanadium, Chromium, Manganese, Iron, Cobalt, Nickel, Copper, Zinc, Yttrium, Zirconium, Niobium, Molybdenum, Technetium, Ruthenium, Rhodium, Palladium, Silver, Cadmium, Lanthanum, Hafnium, Tantalum, Tungsten, Rhenium, Osmium, Iridium, Platinum, Gold, and Mercury.

12. The microfluidic device (100) according to claim 9, wherein the reagent (112) is configured to detect a psychotherapeutic drug.

13. The microfluidic device (10) according to claim 12, wherein the psychotherapeutic drugs comprise chlorpromazine (Thorazine), fluphenazine (Prolixin), haloperidol (Haldol), loxapine (Loxitane), thiothixene (Navane), clozapien (Clorazil), olanzapine (Zyprexa), quetiapine (Seroquel), risperidone (Risperdal), armodafinil (Nuvigil), atomoxetine (Stratera), dexmethylphenidate (Focalin), dextroamphetamine (Dexedrine), guanfacine (Intuniv), methylphenidate (Ritalin, Concerta), modafinil (Provigil).

14. The microfluidic device (100) according to any of the previous claims, wherein the reagent (112) is a colorimetric substance, the colorimetric substance is a porphyrinbased chemical.

15. The microfluidic device (100) according to claim 14, wherein the porphyrin is preferably phenylporphyrin, more preferably a tetraphenylporphyrin.

16. The microfluidic device (100) according to any of the previous claims, wherein the reagent (100) is in dry form, or is suspended in a liquid, or in a gel.

17. The microfluidic device (100) according to any of the previous claims, wherein the reagent (112) is combined with at least one activator reagent.

18. The microfluidic device (100) according to any of the previous claims, wherein the de-bubbling means (140) comprises a bubble-trap (118) configured to remove bubbles from the reagent (112).

19. The microfluidic device (100) according to claim 18, wherein the bubble-trap (118) comprises a compartment configured to store volumes 1-500 pL of the reagent (112), the compartment's exits being provided with respective flow restrictors (I, k', m').

20. The microfluidic device according to claim 19, wherein the flow restrictors (I, k', m') comprises a combination of paper flow restrictors, mesh flow restrictors, geometric flow restrictors, and vents.

21. The microfluidic device (100) according to any of the previous claims, wherein the pressure buffer (116) comprises a dead-end microfluidic channel configured to hold volumes from 1-500 pL and having a height between 10-2000 pm.

22. The microfluidic device (100) according to the previous claims, wherein the read-out chamber (108) comprises at least one vent.

23. The microfluidic device (100) according to the previous claims, wherein the capillary channel (106) comprises a microfluidic metering channel for metering the predetermined volume of the liquid filtrate (132).

24. The microfluidic device (100) according to claim 23, wherein the microfluidic metering channel is configured to hold volumes between 1-500 pL, preferably between 1-100 pL, and more preferably between 1-5 pL.

25. The microfluidic device (100) according to claim 23 or 24, wherein the microfluidic metering channel has a height between 10-2000 pm.

26. The microfluidic device (100) according to any of the previous claims, wherein the readout chamber (108) is configured to be used in conjunction with a separate read-out analysis apparatus.

27. A system for analysing a component in a liquid sample, the system comprising the microfluidic device (100) according to any of the claims 1 to 26 and a separate readout analysis apparatus configured for optical readout, either vertically, diagonally, and/or horizontally.

28. The system according to claim 27, wherein the optical readout method is at least one of colorimetric, and fluorescent.

29. A method of measuring a component in a liquid sample (130), comprising the following actions at a microfluidic device (100):

• by an inlet port (102), providing a liquid sample (130), • by a capillary driven sample separation means (104), separating a substantially particle-free liquid filtrate (132) from the liquid sample (130),

• by a capillary channel (106) connecting the inlet port (102) and a read-out chamber (108), metering a pre-determined volume of the liquid filtrate (132),

• by a reagent storage means (110) comprising a reagent (112) and an injection means (114), injecting the reagent (112) in the capillary channel (106) after having been de-bubbled by a de-bubbling means, whereby the predetermined volume of the liquid filtrate (132) is fed into the read-out chamber (108) to be mixed and react with the injected reagent (112) in the read-out chamber (108),

• detecting a color, light absorption, or light intensity of the mixed reagent (112) and the liquid filtrate (132) in the read-out chamber (108), and

• determining a concentration of the component based on the detected color, light absorption, or light intensity.

30. The method according to claim 29, wherein the liquid sample (130) is 1-100 pL blood, and the substantially particle-free filtrate (132) is blood plasma.

31. The method according to any of the claims 29 to 30, wherein the reagent (112) comprises a colorimetric substance for detecting at least one of: medical drugs, psychotherapeutic drugs, and metallic ions.

32. The method according to any of the claims 29 to 31, wherein the reagent (112) comprises at least one of a colorimetric substance, and a fluorescent substance.

33. The method according to any of the claims 29 to 32, wherein the reagent (112) comprises a colorimetric substance for detecting at least one of: medical drugs, psychotherapeutic drugs, and metallic ions.

34. The method according to claim 33, wherein the reagent (112) is configured to detect an ion.

35. The method according to claim 34, wherein the ion comprises one of Lithium, Sodium, Potassium, Rubidium, Cesium, Francium, Beryllium, Magnesium, Calcium, Strontium, Barium, Radium, Aluminium, Gallium, Indium, Tin, Thallium, Lead, Bismuth, Scandium, Titanium, Vanadium, Chromium, Manganese, Iron, Cobalt, Nickel, Copper, Zinc, Yttrium, Zirconium, Niobium, Molybdenum, Technetium, Ruthenium, Rhodium, Palladium, Silver, Cadmium, Lanthanum, Hafnium, Tantalum, Tungsten, Rhenium, Osmium, Iridium, Platinum, Gold, and, Mercury.

36. The method according to claim 33, wherein the reagent (112) is configured to detect a medical drug, preferably a psychotherapeutic drug.

37. The method according to claim 36, wherein the psychotherapeutic drugs comprise chlorpromazine (Thorazine), fluphenazine (Prolixin), haloperidol (Haldol), loxapine (Loxitane), thiothixene (Navane), clozapien (Clorazil), olanzapine (Zyprexa), quetiapine (Seroquel), risperidone (Risperdal), armodafinil (Nuvigil), atomoxetine (Stratera), dexmethylphenidate (Focalin), dextroamphetamine (Dexedrine), guanfacine (Intuniv), methylphenidate (Ritalin, Concerta), modafinil (Provigil).

38. The method according to any of the claims 29 to 37, wherein the reagent (112) is a colorimetric agent, the colorimetric agent is a porphyrin-based chemical.

39. The method according to claim 38, wherein the porphyrin-based chemical is preferably phenylporphyrin, more preferably a tetraphenylporphyrin.

40. The method according to any of the claims 29 to 39, wherein the reagent (100) is in dry form, or is suspended in a liquid, or in a gel.

41. The method according to any of the claims 29 to 40, wherein the reagent (112) is combined with at least one activator reagent.

42. The method according to any of the claims 29 to 41, wherein at least one of the actions of reading the color and determining the concentration is performed by a separate read-out analysis apparatus configured to detect any of the color, the light absorption, and the light intensity, and determining the concentration based on the detected color, light absorption, or light intensity.