MICROFLUIDIC DEVICE, PRODUCTION OF A MICROFLUIDIC DEVICE AND METHOD AND SYSTEM FOR PERFORMING INORGANIC DETERMINATIONS

Abstract

A method of producing a microfluidic device, including providing at least two solid layers and at least one reagent disc comprising a support disc carrying at least one dry reagent, arranging the reagent disk(s) and stacking the solid layers to form a microfluidic channel arrangement including at least one opening into a channel of the microfluidic channel arrangement and wherein the reagent disk(s) is located in the microfluidic channel arrangement.

Claims

1-95. (canceled)

96. A microfluidic device comprising a stack of at least two solid layers forming a microfluidic channel arrangement there between and at least one opening into the microfluidic channel arrangement wherein the microfluidic device comprises at least one reagent disc at least partly located in said microfluidic channel arrangement, wherein said reagent disc comprises a membrane impregnated with an ionophore cocktail, comprising an ionophore for a target ion.

97. The microfluidic device of claim 96, wherein said reagent disc comprises a support disc carrying at least one dry reagent.

98. The microfluidic device of claim 96, wherein at least a section of the microfluidic channel arrangement immediately upstream to said location of said reagent disc is free of absorbent material.

99. The microfluidic device of claim 96, wherein the ionophore cocktail comprises a color former, which ensures a color change upon reaction between the ionophore and the target ion.

100. The microfluidic device of claim 99, wherein the color former comprises at least one of a chromogenic compound and a ionophore reaction sensitive dye.

101. The microfluidic device of claim 100, wherein the color former comprises at least one of Fluorescein octadecyl ester, Nile Blue, 3,6-Didodecyloxy-4,5-dimethyl-o-phenylene-bis(mercury chloride), ETH 9033, 4[4-(Dioctylamino)-phenylazo]-3-nitro-benzaldehyde, Chromoionophore CR-514, 9-Dimethylamino-5-[4-(16-butyl-2,14-dioxo-3,15-dioxaeicosyl)phenylimino]benzo[a]phenox azine, ETH 2439, 9-(Diethylamino)-5-[(2-octyldecyl)imino]benzo[a]phenoxazine, ETH 5350, 4′,5′-Dibromofluorescein octadecyl ester, ETH 7075, 3′,3″,5′,5″-Tetrabromophenolphthaleinethyl ester, TBPE, 4-Dibutylamino-4′-(trifluoroacetyl)stilbene, ETH 4003 or any combination comprising one or more of these.

102. The microfluidic device of claim 96, wherein the membrane comprises at least of the materials polyvinylchloride (PVC), polyvinylalcohol (PVA), polyvinylbutyral (PVB), polyvinylpyrrolidone (PVP), cellulose, nitrocellulose, nylon, gelatin, silk or chitosan.

103. The microfluidic device of claim 96, wherein the reagent disc is an ion specific polymeric membrane formulated with the ionophore cocktail comprising the ionophore and the color former in an organic solvent.

104. The microfluidic device of claim 96, wherein the ionophore is a ionophore for at least ine of the ions NH4+, K+, (NO3)−, (NO2)−, (PO4) 3−, Mg2+, Na+, Cl—, Zn2+, Cr3+, Sb3+, SbO+,Fe2+, Cd2+, B3+, Ni2+, Pb2+, As3+, Co2+or Co3+.

105. The microfluidic device of claim 96, wherein the ionophore is an ionophore for selected from tetradodecylammonium nitrate (TetraDDA), Tridodecylmethylammonium nitrate (TriDDA, methyltridodecylammonium chloride (MTDA), 9,11,20,22Tetrahydrotetrabenzo[d,f,k,m] [1,3,8,10]tetraazacyclotetradecine10,21-dithione, 9-Hexadecyl-1,7,11,17-tetraoxa-2,6,12,16-tetraazacycloeicosane, Methyltridodecylammonium nitrate; (TDMA-NO3), Tridodecylmethylammonium nitrate, Tetraoctadecylammonium bromide, nonactin,valinomycin, lasalocid, salinomycin, Potassium ionophore- BME 44 (2-Dodecyl-2-methyl-1,3-propanediyl bis[N[5′-nitro(benzo-15-crown-5)-4′-yl]carbamate], BME 44), Bis[(benzo-15-crown-4)-4′-ylmethyl]pimelate, 4-tert-Butyl-2,2,14,14-tetrahomo-2a,14a,dioxacalix[4]arene-tetraacetic acid tetra-tert-butyl ester 9-Decyl-1,4,7-triazacyclodecane-8,10-dione.

106. The microfluidic device of claim 96, wherein the microfluidic channel arrangement comprises two or more reagent discs wherein at least one of the reagent discs is located downstream to at least one other of the reagent discs at least one reaction chamber.

107. The microfluidic device of claim 96, wherein the microfluidic channel arrangement comprises two or more reagent discs located in a common reaction chamber of the microfluidic channel arrangement, said two or more reagent discs are optionally located on top of each other or laterally to each other.

108. The microfluidic device of claim 96, wherein at least one of the solid layers forming the microfluidic channel arrangement has a hydrophilic surface forming a surface of the microfluidic channel arrangement, said hydrophilic surface is provided by a hydrophilic adhesive applied to the solid layer.

109. A method of performing a plurality of inorganic determinations of preselected matter, the method comprising preparing an aqueous sample from the preselected matter and performing an assay comprising at least two quantitative inorganic colorimetric determinations of respective preselected inorganic units or compounds thereof, of at least a liquid portion of said sample, wherein said at least two inorganic colorimetric determinations is performed at different preselected pH values, wherein the colorimetric determinations comprises providing a microfluidic device comprising at least one microfluidic furcated channel arrangement comprising an inlet and at least a first branch and a second branch, each branch comprises a first reaction site and a second reaction site in flow direction further from the inlet than the first reaction site, wherein the first reaction site of the first branch comprises a first dry buffer having a first pH value upon aqueous dissolution and the first reaction site of the second branch comprises a second dry buffer having a second pH value upon aqueous dissolution and wherein each of the second reaction sites comprises respective colorimetric reaction agents, feeding the sample into the inlet of the microfluidic device, allowing respective portions of the sample dissolving respectively the first buffer and the second buffer and thereafter providing respective color reactions by reacting with the respective colorimetric reaction agents, reading at least one color parameter of each of said respective color reactions and correlating said respective read color parameters to respective standard curves each representing color parameter relative to content of said respective preselected inorganic unit or compounds(s) thereof, wherein at least one of the colorimetric reaction agent is provided by a membrane impregnated with an ionophore cocktail, comprising an ionophore for a target ion of the inorganic unit to be determined.

110. The method of claim 109, wherein the dry buffers are selected from buffers, which upon aqueous dissolution having pH values in the interval from about 1 to about 11, wherein the dry buffers comprises buffers comprising one or more of citrate buffer, sodium hydroxide buffer, potassium hydroxide buffer, PBS buffer and/or one or more of the buffers of Good's buffers or any modifications thereof.

111. The method of claim 109, wherein the preparation of the sample comprises adding a nonionic surfactant, wherein the preselected matter is environmental matter selected from soil, water, leaf, plant tissue like stems and buds.

112. A method of producing a microfluidic device according to claim 96, wherein the method comprises providing at least two solid layers stacking said at least two solid layers to form a microfluidic channel arrangement comprising at least one opening into a channel of the microfluidic channel arrangement, wherein the method further comprises producing at least one reagent disc and arranging said reagent disc between said at least two solid layers to provide that at least a portion of the reagent disc is located in said microfluidic channel arrangement downstream to said at least one opening into the channel, wherein said reagent disc comprises a membrane impregnated with an ionophore cocktail, comprising an ionophore for a target ion.

113. The method of claim 112, wherein the method of producing said reagent disc(s) comprises providing a support structure, adding a solution comprising at least one reagent, performed by a deposition technique, drying said solution and cutting said reagent disc(s) from said support structure carrying said dried reagent, wherein the method comprises adding two or more layers comprising reagent(s), wherein one layer comprising reagent(s) comprises a buffer and another layer comprising a reactant for a target organic or inorganic molecule or ion.

114. The method of claim 112, wherein said microfluidic channel arrangement comprises at least one microfluidic furcated channel branching in at least a first branch and a second branch, wherein each of said first branch and second branch comprises a first reaction site and a second reaction site in flow direction further from the inlet than the first reaction site, wherein said first reaction site comprises a first dry buffer having a first pH value upon aqueous dissolution and said first reaction site of the second branch comprises a second dry buffer having a second pH value upon aqueous dissolution and wherein each of the second reaction sites comprises respective colorimetric reaction agents, wherein at least one of said reaction agents or dry buffer is in the form of a reagent disc comprises a support disc carrying at least one dry reagent.

115. The method of claim 112, wherein said reagent disc has a rear side and wherein the reagent disc has an adhesive at its rear side and the method comprising adhering said rear side of said reagent disc to one of said solid layers and/or wherein one of said solid layers comprises an adhesive and the method comprises adhering said rear side of said reagent disc to said solid layer, wherein the at least one reagent disc is adhered to said solid layer to provide that at least a portion of the reagent disc is located in a reaction chamber of said microfluidic channel arrangement, wherein the step of arranging said at least one reagent disc comprises using a computer controlled micropositioning stage, capable of generating mechanical motion with micrometer or nanometer resolution and wherein said method comprises locating two or more reagent discs in said microfluidic channel arrangement in same or different reaction chambers.

Description

BRIEF DESCRIPTION OF THE EXAMPLES AND DRAWING

[0224] The invention is being illustrated further below in connection with selected examples and embodiments and with reference to the figures. The figures are schematic and may not be drawn to scale.

[0225] FIG. 1 illustrates an embodiment of a microfluidic device carrying a number of reagent discs and suitable for use in an embodiment of the method of performing inorganic determinations of the invention.

[0226] FIGS. 2a and 2b illustrate two different shapes of reagent discs.

[0227] FIG. 2c illustrates rows of reagent discs under production.

[0228] FIG. 3 is an exploded view of an embodiment of a microfluidic device.

[0229] FIG. 4 is a top view of an embodiment of a microfluidic device

[0230] FIG. 5 is an example of a process diagram of an embodiment of the method of producing a microfluidic device of the invention.

[0231] FIG. 6 is an example of a process diagram of an embodiment of performing inorganic determinations using an embodiment of the system of the invention.

[0232] The microfluidic device 10 shown in FIG. 1 comprises a furcated channel arrangement 1 comprising a number of fluid interconnected channels, comprising primary channels 1a, 1b, 1c. The three primary channels are in fluid connection with a common, not shown inlet for feeding a sample to the microfluidic device. A first 1a of the primary channel comprises a first branch 2a and a second branch 2b, A second 1b of the primary channel comprises a third branch 2c and a fourth branch 2d. Each of the first, second and third branches comprises a first reaction site 4a, 4b, 4c and a second reaction site 5a, 5b, 5c in flow direction further from the inlet than the first reaction site. Each of the first reaction sites 4a, 4b, 4c comprises a reagent disc b1, b2, b3. As explained above the reagent discs b1, b2, b3 in at least two and preferably more first reaction sites may comprise a dry buffer. For example, reagent disc b1, may comprise a buffer having a first pH value upon aqueous dissolution, reagent disc b2, may comprise a second dry buffer having a second pH value upon aqueous dissolution and reagent disc b3, may comprise a third dry buffer having a third pH value upon aqueous dissolution.

[0233] Each of the second reaction site 5a, 5b, 5c comprises a respective reaction disc r1 r2, r3 comprising colorimetric reaction agents Since the sample portions arriving at the second reaction sites 5a, 5b, 5c may adjusted to a preselected pH value the colorimetric reaction agents of the reaction discs r1, r2, r3 may be pH sensitive reagents, e.g. with reaction optimum at different pH value. As explained above, this makes it possible for a user to make several pH sensitive inorganic determinations at the same time in a very simple manner.

[0234] In this embodiment, the fourth branch 2d comprises only one single reaction site 5d comprising a reaction disc r4, which may preferably comprise colorimetric reaction agents, which do preferably not require a specific pH value.

[0235] The third primary channel 1c comprises a single reaction/read out site 5e, which may or may not comprise a reaction disc. Here it is illustrated to comprise a reaction disc r5.

[0236] This third primary channel 1c and the reaction/read out site 5e may be arranged for performing a further inorganic determination. The third primary channel 1c and the reaction/read out site 5e may advantageously be arranged for determine when all the reactions in the other reaction sites are terminated.

[0237] Thereby it may be simpler for the user to determine when the reactions are finished and the microfluidic device 10 is ready for reading out. For example, where a determination unexpected gives a lower result, the user may think that the reaction is not final and then the user may waste time.

[0238] To ensure that fractions of the sample reaches the reaction site 51 of the third primary channel 1c at a desired time later than fractions of the sample reaches the other secondary reaction sites 5a, 5b, 5c, 5s, the third primary channel 1c may be shaped to delay the liquid flow, e.g. by folding the channel e.g. with accordion folds A as illustrated. Any other delay arrangements of the third primary channel 1c may be provided.

[0239] The channels of the channel arrangement may be folded as desired and for example also the branches 2a, 2b, 2c, 2d may be folded to regulate the velocity of the sample in the respective channel branches. The branches 2a, 2b, 2c, 2d further comprises escape openings for allowing gas escaping from the respective branches 2a, 2b, 2c, 2d as the sample flow is progressing therein. The escape opening is located downstream to the reaction chambers 5a, 5b, 5c, 5d. The third primary channel 1c may likewise comprise a downstream located escape opening.

[0240] The dry buffers, the reaction agents and/or the reaction discs may advantageously be as described elsewhere herein.

[0241] The skilled person will understand that the channel arrangement 1 may be constructed to make as many determinations simultaneously as practically desired and the determinations may involve pH sensitive reagents at various pH value as well as non pH sensitive reagents.

[0242] FIG. 2a shows a round reagent disc prior to being applied to a reaction chamber of a microfluidic device. The reaction disc comprises a support disc 12a e.g. as described elsewhere herein. The support disc 12a carries the dry reagents 11a. Here it is illustrated that the reagents is evenly spread over the entire layer of the support disc 12a. In a variation there of the reagents are distributed differently, for example dropwise, in lines or any conveniently way.

[0243] The reagents may adhere to the support disc by being applied on moist form and thereafter dried. In an embodiment, the reagents are adhered to the support disc, e.g. by an adhesive located at the top surface of the support disc.

[0244] The support disc may advantageously carry a pressure sensitive adhesive on its bag side—i.e. the side opposite to the front side carrying the reagents. In order to handle the support disc with adhesive on its rear side the support disc preferably comprises a release paper, which may be removed prior to applying the reagent disc to the reaction chamber of a microfluidic device. The pressure sensitive adhesive on the rear side of the reagent disc makes it very simple to positioning the reagent disc in the desired location. For example the reagent disc may be positioned at any desired location in a reagent chamber and the method also make it possible to positioning two or more equal or different reagents discs in a common reagent chamber in a desired configuration.

[0245] FIG. 2b shows a reagent disc with another shape. Here it is rectangular with rounded corners. It should be appreciated that the reagent disc may have any shape.

[0246] The reaction disc comprises a support disc 12b e.g. as described elsewhere herein. The support disc 12b carries the dry reagents 11b. Here it is illustrated that the reagents is applied in lines of reagents. Each line may be different or equal.

[0247] The support disc may advantageously carry a pressure sensitive adhesive on its rear side. In order to handle the support disc during production the support disc preferably comprises a release paper 13b. Advantageously a plurality of reagent discs shares release paper 13b and it withdrawn from the release paper immediately before being applied to a reaction chamber. As illustrated the release paper 13b is a long strip, which may carry several reagent discs.

[0248] FIG. 2c, illustrated a series of reagent discs during production. The support structure 15 preferably carries a pressure sensitive adhesive on its rear side and the pressure sensitive adhesive is covered with a release paper.

[0249] The reagents is applied to the support structure e.g. is predetermined locations or spread over the entire surface and the reagents are dried e.g. by allowing it to dry by air or using a blower or other means. The reagent discs 14 are cut without cutting through the release paper. Here the reagent discs are round, but they could have any shape as mentioned above. Thereafter the support structure including the release paper is cut along lengthwise cutting lines 16 to obtain three strips of release paper carrying rows of reagent discs.

[0250] The reagent discs may thereafter individually be removed from the release paper and mounted in a reaction chamber of a microfluidic device.

[0251] FIG. 3 illustrates a variation of the microfluidic device of FIG. 1 in exploded view. The microfluidic device is it produced by a method comprising applying three solid layers L1, L2, L3 together.

[0252] The bottom layer L1, may be a layer or layers of polymer or paper or a combination thereof, such as a layered product and the bottom pater may simply be cut out. In an alternative version, the bottom layer is produced by injection molding.

[0253] The middle layer L2 may advantageously be produced by cutting e.g. as described above, e.g. by laser cutting or a stamping the layer or layers of polymer or paper or a combination thereof. The cutting of the middle layer L2, comprises cutting through the layer L2 to form the channel arrangement 21. The middle layer will then have a through hole shaped as the channel arrangement comprising an inlet 26, channel branches with reaction chambers for buffer reaction 28, reaction chambers for colorimetric reaction and a downstream location 27 for escape openings. The middle layer should advantageously have a selected thickness, to provide the depth of the channels of the channel arrangement.

[0254] The top layer L3 make likewise be cut, where the cutting comprises providing a through hole 26a for the inlet 26 and escape openings 27a into the downstream location 27.

[0255] The reagent discs 24, 25 may be positioned onto the bottom layer L1 before or after assembling the bottom layer L1 with the middle layer L2, but prior to applying the top layer L3. The reagent discs 24, 25 are advantageously adhered to the bottom layer using the pressure sensitive adhesive located at the rear side of the reagent discs 24, 25. In an alternative embodiment the front surface of the bottom layer L1 facing the middle layer L2 carries a pressure sensitive adhesive.

[0256] The three layers L1, L2, L3 are advantageously mounted to each other using pressure sensitive adhesive.

[0257] The branches 2a, 2b, 2c, 2d further comprises escape openings for allowing gas escaping from the respective branches 2a, 2b, 2c , 2d as the sample flow is progressing therein. The escape opening is located downstream to the reaction chambers 5a, 5b, 5c, 5d. The third primary channel 1c may likewise comprise a downstream located escape opening.

[0258] FIG. 4 show an embodiment of a microfluidic device 30, comprises a channel arrangement 31 with an inlet 34 and a number of branches in fluidic connection with the inlet 34 and with respective reaction chambers 37 with reaction discs comprising respective colorimetric reaction agents. As shown the branch lengths L1, L2, L3, L4, L5 from the inlet to the respective reaction chambers 37 differs, such that L1 and L5 are longer than L2 and L4, which again are longer than L3.

[0259] It should be appreciated that the branches may be designed with any desired branch length, e.g. by providing a branch with folds.

[0260] FIG. 5 is an example of a process diagram of an embodiment of the method of producing a microfluidic device of the invention and specifically the step of producing and locating the reaction discs in desired reaction chamber of microfluidic channel arrangements of microfluidic devices.

[0261] First in step 40 a desired substrate is provided e.g. as described above. The selected reagents are in steps 41 and 42 applied to the front side of the substrate and dried. The reagents may be applied applied to the substrate in form of one or more mixtures of reagents or one reagent at a time with or without intermediate step(s) of drying. In this example, a double sided adhesive with a peel-off slip-layer on one of its side is adhered to the rear side of the substrate in step 43. Thereafter the substrate with the adhesive is cut. In a first cut in step 44a, the substrate with the adhesive is cut in a first direction e.g. in lines, without cutting through the peel-off slip-layer. Thereafter in step 44b the substrate with the adhesive is cut in a second direction e.g. in lines crossing the first direction lines—The second cut may optionally be fully through the substrate with the adhesive and peel-off slip-layer. Alternatively the peel-off slip-layer is not fully cut.

[0262] Thereafter in step 45 the Cut substrate—still supported by the peel-off slip-layer is arranged on a computer controlled micropositioning stage, capable of generating mechanical motion with micrometer or nanometer resolution. In step 46 the individual reagent discs are released from the peel-off slip-layer and positioned in a reaction chamber or on a solid layer adapted to form part of a reaction chamber of a microfluidic device by the micropositioning stage. The micropositioning stage is capable of locating the reagent discs with a very high accuracy and very fast.

[0263] FIG. 6 illustrates an example of a process diagram of an embodiment of performing inorganic determinations using an embodiment of the system of the invention.

[0264] The process diagram in FIG. 6 illustrates a process of operation of the system of an embodiment of the invention.

[0265] First step 50 is to withdraw a sample of soil and filling it into a sample bag. In step 51, at the location of withdrawing the sample, the barcode of the sample bag is scanned with a scanner in a first mode. The scanner form part of a scanner arrangement as described above.

[0266] At the same location or at any other location e.g. a central testing location in step 52a and 52b, which may be in any order, a fraction of the sample is withdrawn from the sample bag and an extract is prepared. Further, the barcode of the sample bag is scanned with a barcode scanner of the scanner arrangement in second mode. Now the geographical location of taking the sample of the sample bag is associated to the selected microfluidic device.

[0267] In step 53a a microfluidic device is selected and scanned with a scanner of the system. In step 53b the liquid extract is added to the selected microfluidic device. The skilled person will understand that the order of scanning the microfluidic device and adding the sample may be any order.

[0268] After a prescribed testing time, which may be for example ½ minute or 5 minutes, the selected microfluidic device is in step 54a inserted into a reader which is associated with the scanner arrangement. At the same time—before or after—the bar code of the microfluidic device is scanned. Thereby the result obtained from the selected microfluidic device will be associated to the geographical location of taking the sample that is under test.

[0269] In an alternative embodiment the microfluidic device is not scanned and need not carrying a barcode and instead the step of scanning the sample bag with the scanner in second mode may be performed in step 54b instead of in step 52a.

[0270] The result obtained from the reader is stored in step 55 such that the test result is associated to the geographical location of taking the sample. The test result is uploaded to cloud for generating a map in step 56a and in step 56b the result is listed on a screen together of results of samples from other geographical locations.

EXAMPLE 1—SOIL SAMPLE

[0271] 1. A pre weighed sample (1-5 g) of soil is extracted in a syringe using a soil extraction solution for 15 minutes.

[0272] 2. After extraction two drops of the sample are fed into the inlet of a microfluidic device as shown in FIG. 1, but without the third primary channel 1c and wherein reaction channel 2d comprises a first reaction 4d chamber downstream to the reaction chamber 5d, which is then referred to as second reaction chamber 5d.

[0273] The four branches 2a, 2b, 2c, 2d are adapted for performing four different determinations.

[0274] Nitrate:

[0275] The nitrate assay branch 2b has a reaction disc carrying a reducing agent, zinc loaded in first reaction site 4b and a reaction disc carrying a griess reagent in second reaction site 5b.

[0276] Potassium:

[0277] The potassium assay branch 2a has a reaction disc carrying 0.002 M citric acid buffer of pH 6.5 loaded in first reaction site 4a and a reaction disc carrying an ionophore cocktails in second reaction site 5a.

[0278] The ionophore cocktails recipe is a follows:

[0279] 0.52% Nile blue 1% Potassium ionophore- BME 44 0.48% Potassium tetrakis(4-chlorophenyl) borate 66% Bis(2-ethylhexyl)sebacate 32% Poly(vinyl chloride)

[0280] Ammonium:

[0281] The ammonium assay branch 2c has a reaction disc carrying TrisHCl buffer of pH 7 loaded in first reaction site 4c and a reaction disc carrying an ionophore cocktails in second reaction site 5c.

[0282] The ionophore cocktails recipe is a follows:

[0283] 2.00 wt % Ammonium ionophore I 1.2 wt % Potassium tetrakis(4-chlorophenyl)borate 2.100 wt % Chromoionophore III 65.50 wt % Bis(2-ethylhexyl)sebacate (84818) 15.00 wt % Poly(vinyl chloride) high molecular weight 15.00 wt % Polyurethane

[0284] Phosphate:

[0285] The phosphate assay branch 2d has a reaction disc carrying H2SO4, 5N pH 1 buffer in first reaction site 4d and a reaction disc carrying the following reagents in second reaction site 5d:

[0286] antimony potassium tartrate, 4mM

[0287] ammonium molybdate, 0.27M

[0288] 0.1 M ascorbic acid solution.

[0289] The liquid is allowed to through the channels and reached the reaction chambers which provide signals.

[0290] The microfluidic device is then inserted in the analysis device comprises the reader and computer system and the algorithms on the device predict the quantitative value of the inorganic molecule of interest.

EXAMPLE 2—URINE SAMPLE

[0291] A urine sample is provided and optionally diluted.

[0292] A two drops of the sample are fed into the inlet of a microfluidic device. The microfluidic device is identical to the microfluidic device used in example 1.

[0293] After the sample has reached and reacted with the reagents, the microfluidic device is then inserted in the analysis device comprises the reader and computer system and the algorithms on the device predict the quantitative value of the inorganic molecule of interest.

EXAMPLE 3—PLANT SAP

[0294] Sap is extracted from the plant for example from the leaf or stem petiole.

[0295] Two drops of sap are fed into the inlet of a microfluidic device and the analysis is performed as in example 2.

EXAMPLE 4—PRODUCTION OF REAGENT DISCS

[0296] For each type of reagent disc a reagent solution is produced for example 1 litre reagent solution

[0297] An example of producing reagent discs and a microfluidic device with reagent discs. A support structure is provided e.g. in form of long length of pater or sheets of A4 or A5 size etc.

[0298] The support structure advantageously is selected in dependence of the reagent. The pore size and matrix composition of the support structure may affect the embedding of the reagents.

[0299] The support structure is dipped into the solution for 60 seconds and where after the support structure is air-dried in a low humidity area, e.g. by hanging vertically using hooks. The time required for drying differs in dependence on the reagent solution and the support structure used.

[0300] After drying the support structure with the dried reagents is cut into Strips using a vinyl cutter and pre-cuts into specific sized circular discs of 2-3 mm diameter is performed, such that the circular discs remain connected to the strip, but can be removed by a mechanical picking process. The reagent discs are now ready to be used in the microfluidic device.

[0301] In a variation thereof, the support structure with dry reagents is cut into sheets of size A5 or 128×80 cm or 100×100 cm.

[0302] In a variation thereof, a die-cutter with a selected height according to the thickness of the support structure is applied for cutting the support structure with dry reagents.

EXAMPLE 5—PRODUCTION OF A MICROFLUIDIC DEVICE

[0303] Three layers of material L1, L2 and L3 as shown in FIG. 3 are provided. The Bottom layer L1 carries a pressure sensitive adhesive on its middle layer facing side and the top layer L3 carries a pressure sensitive adhesive on its middle layer facing side.

[0304] The strips comprising the circular reagent discs produced in example 4 are then fed into an automatic pick and place machine. The circular reagent discs are picked and placed at predetermined locations onto and adhered to the bottom layer L1 using an automated robot arm. Subsequently, the middle layer L2 and the top layer L1, which have an adhesive on one side, are assembled.

EXAMPLE 6—PRODUCTION OF A MICROFLUIDIC DEVICE

[0305] In a 100 hectare field, 40-50 spots are selected and a soil sample is collected from each spot. At the collection spot the soil sample is placed in a sample bag, which carries a unique bar code and the bar code is scanned using a barcode scanner of a barcode scanner arrangement comprising a global positioning system (GPS) and associated to a reader, wherein the barcode scanner is operating in a first mode, such that geographic coordinates of the location of taking the soil sample are associated with the unique barcode and the bag with the soil sample.

[0306] The soil sample bags are brought to a test location, where each of the respective soil samples are tested by performing a plurality of inorganic determinations using the method and microfluidic devices as described above and comprising for each sample. [0307] withdrawing a portion of the preselected matter, [0308] subjecting the portion of environmental matter to an extracting process comprising mixing the sample with a predetermined amount of an aqueous extracting solvent, and [0309] filtering off solid parts, [0310] adding the sample to a microfluidic device [0311] applying the microfluidic device in the reader, which is associated to the barcode scanner arrangement [0312] scamming the barcode of the sample bag wherefrom the sample under analysis was withdrawn using a barcode scanner of the barcode scanner arrangement, where the scanner is operating in a first mode.

[0313] Thereby the geographic coordinates of the location of taking the soil sample are associated with the test result obtained from the microfluidic device with the liquid sample, which is extract from soil taking at the geographic coordinates of the location of taking the soil sample.

[0314] The data gathered is using mathematic models and statistics to determine the inorganic concentration of the ions from the reader. The data gathered in terms of test results gathered from microfluidic devices is stored on a computer system and displayed either directly on the screen of the reader or on a IoT platform (Internet of Thinks platform) in the form of a map or list.

EXAMPLE 6—PRODUCTION OF A MICROFLUIDIC DEVICE

[0315] Two solid polymer layers is provided, including a channel forming layer and a cover layer. The channel-forming layer is milled to form a carved channel arrangement with the desired depths and widths of reaction chambers and the flow channels. One or more selected reagent discs are prepared and positioned at the bottom of one or more of the carved reaction chambers. The cover layer carries a pressure sensitive adhesive and is stacked with the channel-forming layer to form the microfluidic channel arrangement.

[0316] In a first variation thereof, the channel arrangement is formed in the channel-forming layer by laser ablation.

[0317] In a second variation thereof, the channel arrangement is formed in the channel-forming layer molding of the layer.

[0318] In a third variation thereof, the channel-forming layer with the channel arrangement is formed by stacking at least two layers a first basic layer and a second middle layer with through-cuts forming the channel arrangement. The basic layer and/or the middle layer may comprise a pressure sensitive adhesive for fixing to each other.

[0319] In an embodiment, the middle layer carries an adhesive on both of its sides for adhering both to the first basic layer and to the cover layer.

[0320] It has been observed that, in this third variation comprising three solid layers, a basic layer, a middle layer and a cover layer only one of the layers need to be hydrophilic to provide a desired uniform and fast flow of a hydrophilic liquid sample, without addition of surfactant to the liquid sample.

[0321] In a fourth variation thereof, two selected reagent discs are prepared and positioned at the bottom of a common reaction chamber.

[0322] In a fifth variation thereof, two selected reagent discs are prepared and positioned at the bottom of separate reaction chambers, such as separate reaction chambers of separate branches of the microfluidic channel arrangement or separate reaction chambers where one of the reaction chambers is located downstream to the other one of the reaction chambers.

[0323] In a sixth variation thereof, one or more of the layers has a hydrophilic surface forming a surface area of the microfluidic channel arrangement. For example the cover layer may be of a hydrophilic PMMA or a polyester coated with a surfactant e.g. as the materials described above.