Analyzing device, electrolyte concentration measurement method, and analyzing apparatus

Abstract

In electrolyte concentration measurement employing an analyzing device that measures an electrolyte concentration by measuring an electric potential difference, a sample remains on the surface of the analyzing device even after the measurement has been performed, and therefore the present invention provides an analyzing device that reduces the risk of the sample trickling along the surface of a cover of the analyzing device after the measurement and contaminating the hand or arm of an operator or the measurement location.　This analyzing device is characterized in that: a flow passage wall is formed inside a porous substrate by means of a hydrophobic material; the porous substrate is divided by the flow passage wall into a flow passage region surrounded by the flow passage wall and a margin portion located outside the flow passage wall; hydrophobic covers are provided on both surfaces of the porous substrate; the covers are provided with an opening portion for introducing a sample; the area of the margin portion as viewed from the opening portion side is 50% or more of the area of the flow passage region as viewed from the opening portion side; and the margin portion includes a region that is not covered by the cover.

Description

Analytical device, electrolyte concentration measurement method and analytical apparatus

[0001] The present disclosure relates to an analytical device having a flow path region surrounded by a flow path wall provided inside a porous substrate, a method for measuring electrolyte concentration using the analytical device, and an analytical apparatus.

[0002] In recent years, microanalysis chips that utilize micro-sized fine channels to efficiently perform biochemical analysis within a single chip have been attracting attention in a wide range of fields, including biochemical research, medicine, drug discovery, healthcare, the environment, and food.

[0003] In the early 1990s, photolithography and molds were used to form micron-sized fine channels on glass or silicon, and microanalysis chips were developed that could perform sample pretreatment, stirring, mixing, reaction, and detection on a single chip. As a result, miniaturization of testing systems, rapid analysis, and reduction of specimens and waste liquids were realized.

[0004] Electrochemical analysis, which measures the potential between electrodes immersed in the sample to be analyzed, is widely used in the medical and environmental fields. Traditionally, electrochemical analysis has required sophisticated equipment and been performed by technicians, which has limited the fields and resources available for measurement. Therefore, there is a need for inexpensive, easy-to-use, disposable microanalysis chips for electrochemical analysis, which can be used in developing countries and remote areas with limited medical facilities, medical activities at disaster sites, and in airports and other locations where the spread of infectious diseases must be prevented at the border.

[0005] Electrochemical analysis, such as quantifying electrolyte ions in a solution, requires a stable reference electrode that can maintain a constant potential. Conventional glass reference electrodes are expensive and cannot be miniaturized because they require an internal liquid. Furthermore, they require storage in a concentrated ion solution, making them difficult to handle.

[0006] Patent Document 1 proposes a system including a microanalysis chip capable of measuring potential differences using a porous substrate, enabling electrochemical measurements at low cost, with easy handling and disposability. This microanalysis chip includes one or more working electrodes and one reference electrode on a porous substrate. In such a microanalysis chip, electrical continuity between the two electrodes must be established by a fluid during measurement. Patent Document 1 describes introducing a highly concentrated aqueous solution of KCl as a reference solution into a reference region including the reference electrode in order to obtain a stable potential at the reference electrode during measurement.

[0007] Furthermore, Non-Patent Document 1 proposes a filter paper-based analytical chip for measuring Na ion concentration and K ion concentration. This analytical chip has an inlet for introducing a sample, and the introduced sample permeates from the inlet into the working electrode and reference electrode regions, establishing electrical continuity between the two electrodes and measuring the potential difference. To stabilize the potential at the reference electrode, this analytical chip proposes an analytical chip in which KCl ion crystals are deposited on the reference electrode. During measurement, KCl dissolves in the sample, maintaining a high concentration of Cl ions in the reference electrode region, thereby achieving a stable reference electrode potential. Furthermore, an ion-selective membrane formed to cover the working electrode selects only the ions to be measured, allowing measurement to be performed without being affected by other ions.

[0008] There is also a technique for introducing a sample onto a working electrode, as described in Patent Document 2. Patent Document 2 discloses a technique for obtaining high accuracy in measuring the sample concentration of specific ions contained in the sample. The flow path area other than the working electrode is covered with a laminate, leaving only the working electrode exposed, and the sample is introduced in a pinpoint manner. Furthermore, a technique for maintaining sufficient contact between the sample and the working electrode by curving the working electrode is also disclosed. In Patent Document 2, the sample must be maintained in droplet form on the working electrode, which makes it possible to maintain contact between the sample and the working electrode. The working electrode surface must have a certain degree of hydrophobicity, and this technique can be realized by maintaining a droplet shape on the working electrode.

[0009] US Patent Application Publication No. 2016 / 0033438 JP 2023-048923 A

[0010] Nipapan Ruecha, Orawon Chailapakul, Koji Suzuki and Daniel Citterio “Fully Inkjet-Printed Paper-Based "Potentiometric Ion-Sensing Devices" Analytical Chemistry August 29, 2017 Published, 89, pp. 10608-10616

[0011] However, when considering analytical devices configured as described in the aforementioned Patent Document 2, the following problems exist. In such a configuration in which measurement is completed while droplets remain on the analytical device, care must be taken to prevent droplets from scattering on the analytical device when disposing of the used analytical device. For example, if the analytical device is transported and disposed of manually or using a belt, there is a risk that the sample will drip down the hydrophobic cover (laminate) surface of the analytical device and onto the hands, belt, or measurement site. Furthermore, at the disposal site, the sample may also drip down the analytical device, causing a liquid pool and contaminating the disposal site.

[0012] In view of the above-mentioned problems, the present disclosure aims to provide an analytical device that can be safely disposed of by providing a marginal area in advance within the analytical device for absorbing droplets, and providing an area in the marginal area that is not covered by a cover (a sample absorption area) to promote efficient absorption into the marginal area via the absorption area.

[0013] In order to achieve the above object, according to the present disclosure, there is provided an analytical device having a porous substrate formed of a porous material, wherein a flow path wall is formed inside the porous substrate using a hydrophobic material, and the porous substrate is divided by the flow path wall into a flow path region surrounded by the flow path wall and a margin portion located outside the flow path wall, and the flow path region has a first flow path chamber, a second flow path chamber, and a connecting flow path connecting the first flow path chamber and the second flow path chamber, the first flow path chamber has a reference electrode, the second flow path chamber has a working electrode, and the working electrode comprises a hydrophobic material, and a hydrophobic cover is provided on both sides of the porous substrate, and the cover has an opening for introducing a sample that is connected to the second flow path chamber, and the cover is provided so as to cover at least the flow path region except for the opening, and the area of ​​the margin portion as viewed from the opening side is 50% or more of the area of ​​the flow path region as viewed from the opening side, and the margin portion has an area that is not covered by the cover.

[0014] Further, according to the present disclosure, there is provided an analytical device having a porous substrate formed of a porous material, wherein a flow path wall is formed inside the porous substrate from a hydrophobic material, and the porous substrate is divided by the flow path wall into a flow path region surrounded by the flow path wall and a marginal portion existing outside the flow path wall, the flow path region has a first flow path chamber, a second flow path chamber, and a connecting flow path connecting the first flow path chamber and the second flow path chamber, the first flow path chamber has a reference electrode, the second flow path chamber has a working electrode, and the working electrode contains a hydrophobic material, and hydrophobic covers are provided on both sides of the porous substrate, and an opening for introducing a sample, which is communicated with the second flow path chamber, is provided in the cover, and the cover is provided so as to cover at least the flow path region except for the opening, and the area of ​​the marginal portion as viewed from the opening side is defined as A mm ２ The thickness of the marginal portion is T mm, the porosity of the marginal portion is P, and the amount of the sample to be introduced is S mm ３In this case, the following relational expression is satisfied: A×T×P≧S×0.33, and the marginal portion has an area that is not covered by the cover.

[0015] Further, according to the present disclosure, there is provided an analytical device having a porous substrate formed of a porous material, wherein a flow path wall is formed inside the porous substrate from a hydrophobic material, the porous substrate is divided by the flow path wall into a flow path region surrounded by the flow path wall and a margin portion existing outside the flow path wall, the flow path region has a first flow path chamber, a second flow path chamber, and a connecting flow path connecting the first flow path chamber and the second flow path chamber, the first flow path chamber has a reference electrode, the second flow path chamber has a working electrode, the working electrode includes a hydrophobic material, hydrophobic covers are provided on both sides of the porous substrate, the covers are provided with an opening communicating with the second flow path chamber for introducing a sample, the covers are provided so as to cover at least the flow path region except for the opening, and a maximum volume of a droplet of the sample remaining on an exposed surface of the working electrode at the opening is defined as V ｍａｘ mm ３ , the area of ​​the marginal portion as viewed from the opening side is A mm ２ , where the thickness of the marginal portion is T mm and the porosity of the marginal portion is P, V ｍａｘ There is provided an analytical device characterized in that the relationship A×T×P is satisfied, and the marginal portion has an area that is not covered by the cover.

[0016] The present disclosure also provides an electrolyte concentration measurement method and an analysis apparatus that use the analysis device according to the present disclosure.

[0017] By providing a marginal area in the analytical device that absorbs the sample and by providing an area in the marginal area that is not covered by a cover to promote absorption of the sample, the sample can be absorbed at the time of disposal, reducing the scattering and contamination of the sample on the device and handler.

[0018] 10 is a top view of the analytical device in Example 1 before lamination. FIG. 11 is a top view of the analytical device in Example 1 after lamination. FIG. 12 is a cross-sectional view of the analytical device in Example 1 after lamination. FIG. 13 is a perspective view of the analytical device in Example 1 after lamination. FIG. 14 is a top view of the analytical device according to the prior art before lamination. FIG. 15 is a cross-sectional view showing a method for leaving a margin exposed on the side surface of the analytical device in Example 1. FIG. 16 is a perspective view showing the analytical device in Example 1 connected to a measurement unit that measures electromotive force. FIG. 17 is a perspective view showing the step of introducing a droplet of a sample in the method for measuring an electrolyte concentration using the analytical device in Example 1. FIG. 18 is a schematic view showing the state of the analytical device in Example 1 when discarded. FIG. 19 is a perspective view showing a droplet of a sample. FIG. 19 is a perspective view showing a state in which a sample has been introduced into an analytical device in Example 3, the exposed surface of which is a circular working electrode. FIG. 19 is a top view of the analytical device shown in FIG. 8. FIG. 19 is a top view showing a state in which a sample has been introduced into the analytical device shown in FIG. 8. FIG. 19 is a perspective view showing a state in which a sample has been introduced into an analytical device in Example 3, the exposed surface of which is a square working electrode. FIG. 19 is a top view of the analytical device shown in FIG. 10. 11 is a top view showing a state in which a sample has been introduced into the analytical device shown in FIG. 10. FIG. 12 is a top view of an analytical device in Example 4 before lamination. FIG. 13 is a top view of an analytical device in Example 4 after lamination. FIG. 14 is a cross-sectional view of an analytical device in Example 4 after lamination. FIG. 15 is a perspective view of an analytical device in Example 4 after lamination. FIG. 16 is a top view of another analytical device in Example 4 before lamination. FIG. 17 is a top view of another analytical device in Example 4 after lamination. FIG. 18 is a cross-sectional view of another analytical device in Example 4 after lamination. FIG. 19 is a perspective view of another analytical device in Example 4 after lamination. FIG. 19 is a perspective view showing a state of an analytical device in Example 4 during sample absorption. FIG. 20 is a perspective view of another analytical device in Example 4 during sample absorption. FIG. 21 is a top view of an analytical device in Example 5 before lamination. FIG. 22 is a top view of an analytical device in Example 5 after lamination. FIG. 23 is a cross-sectional view of an analytical device in Example 5 after lamination. FIG. 24 is a perspective view of an analytical device in Example 5 after lamination. FIG. 25 is a perspective view showing a state of the analytical device in Example 5 at the time of disposal.Fig. 21B is a schematic diagram of an analytical device in Example 6. Fig. 21C is a perspective view showing a state in which an analytical device in Example 6 and a measurement unit that measures electromotive force are connected. Fig. 21D is a perspective view showing a step of introducing a specimen in a method for measuring electrolyte concentration using the analytical device in Example 6. Fig. 21E is a perspective view showing a part of an analytical device in Example 6 with a tilted belt. Fig. 21F is a perspective view showing an analytical device in the state shown in Fig. 21A. Fig. 21G is a perspective view showing a state of an analytical device in Example 7 at the time of disposal.

[0019] The analytical device, electrolyte concentration measurement method, and analytical apparatus according to the present disclosure for solving the above-mentioned problems will be described based on the following examples. Note that the examples and accompanying drawings shown below are merely examples and are not intended to limit the technical scope of the present disclosure.

[0020] [Example 1] An analytical device according to one embodiment of the present disclosure is an analytical device having a porous substrate formed of a porous material, wherein a channel wall is formed inside the porous substrate using a hydrophobic material, and the porous substrate is divided by the channel wall into a channel region surrounded by the channel wall and a margin portion located outside the channel wall, and the channel region has a first channel chamber, a second channel chamber, and a connecting channel connecting the first channel chamber and the second channel chamber, the first channel chamber having a reference electrode, the second channel chamber having a working electrode, and the working electrode comprising a hydrophobic material, and a hydrophobic cover is provided on both sides of the porous substrate, and the cover has an opening for introducing a sample that is connected to the second channel chamber, and the cover is provided to cover at least the channel region except for the opening, and the area of ​​the margin portion as viewed from the opening side is 50% or more based on the area of ​​the channel region as viewed from the opening side, and the margin portion is an analytical device characterized in that it has an area not covered by the cover. The analytical device according to the present disclosure can have a porous substrate that is flat.

[0021] <Configuration of flow path region> The analytical device 100 in Example 1 will be described with reference to Figures 1A to 1D. Figures 1A and 1B are simplified top views of the analytical device 100. Figure 1A is a view before lamination with a hydrophobic cover, and Figure 1B is a view after lamination. Figure 1C is a simplified cross-section of the analytical device 100 shown in Figure 1B taken along line AA'.

[0022] The analytical device 100 has a flow path region surrounded by a flow path wall 4 provided inside a porous substrate S1. The flow path region is composed of a first flow path chamber 1, a second flow path chamber 2, and a connecting flow path 3. The connecting flow path 3 connects the first flow path chamber 1 and the second flow path chamber 2.

[0023] A reference electrode 5 is disposed in the first flow chamber 1. The reference electrode 5 has a reaction region in the first flow chamber 1 that serves as a contact point with the sample during measurement and measures the electrolyte concentration of the sample. The reference electrode 5 also has a lead wire 8a that is connected to the reaction region and extends continuously onto the flow channel wall 4. The top and side surfaces of the reaction region of the reference electrode 5 are covered with ion crystals 7 such as potassium chloride.

[0024] A working electrode 6 is disposed in the second flow chamber 2. The working electrode 6 also has a reaction region for measuring the electrolyte concentration of the specimen within the second flow chamber 2 as a contact point with the specimen during measurement, and also has a lead wire 8b connected to the reaction region and continuously extending onto the flow channel wall 4. The specimen is introduced into this second flow chamber 2.

[0025] 1A and 1B, the portion covered with the ion crystal 7 and the portion covered with the cover 9 are indicated by dotted lines.

[0026] In Example 1, a hydrophobic resin was placed on a paper porous substrate S1 having a thickness T (shown in FIG. 1C) of 0.1 mm and a porosity of 0.5, and then thermally fixed to form a channel wall 4 that was impermeable to the sample, thereby forming a channel pattern.

[0027] In this example, a paper substrate was used as the porous substrate S1, but the porous substrate is not limited to paper. The porous substrate may be any substrate that generates capillary action in a liquid, and may have pores with a mesh structure such as open cells or nanofibers inside, or may be made of resin, glass, an inorganic substrate, fabric, metal paper, or the like.

[0028] In this example, a porous substrate S1 with a thickness of 100 μm was used, but the thickness of the porous substrate in the analytical device according to the present disclosure is not limited to this and can be selected appropriately depending on the purpose. Porous substrates of approximately 20 μm to 300 μm are often used. If the thickness of the porous substrate is 20 μm or less, it may not be able to maintain its strength as a substrate. Furthermore, if the thickness of the porous substrate is 300 μm or more, materials such as coating films may easily diffuse within the analytical device, which may result in a deterioration in dimensional accuracy. However, depending on the application, a thick porous substrate with a thickness of approximately 600 μm may be used by adjusting the arrangement within the analytical device.

[0029] In the analytical device according to the present disclosure, the porosity of the porous substrate can be appropriately selected depending on the purpose, but is preferably 0.2 or more and 0.9 or less. When the porosity is 0.9 or less, the strength of the substrate is easily maintained, and when it is 0.2 or more, the permeability of the sample liquid (analyte) is good, which is preferable. The porosity is calculated by the following formula: Porosity = (true density - apparent density) / true density. Also, the apparent density (g / cm ３ ) is the apparent density (g / cm ３ )=Basic weight (g / m ２ ) / thickness (mm)×1000.

[0030] The hydrophobic resin forming the flow path wall is not particularly limited, and examples thereof include polyester resin, vinyl resin, acrylic resin, styrene-acrylic resin, polyethylene, polypropylene, polyolefin, ethylene-vinyl acetate copolymer resin, and ethylene-acrylic acid copolymer resin.

[0031] In this example, the flow path pattern was formed by thermal fixing after disposing the hydrophobic resin. In this case, a method of using toner particles as the hydrophobic resin (thermoplastic resin) and thermally fixing the resin using an electrophotographic device can be mentioned. For this method, reference can be made to JP 2021-37612 A. The method of forming the flow path pattern is not limited to this. It is sufficient to form a flow path pattern having the desired flow path region. In addition to a cutting method in which a paper porous substrate is cut to leave only the flow path shape, the flow path walls may be formed using an inkjet printer or a wax printer.

[0032] As shown in FIG. 1B, in order to reduce contamination and evaporation during sample introduction, the analytical device 100 includes a hydrophobic cover 9, such as a laminate film that is impermeable to samples, in addition to the configuration shown in FIG. 1A. In this example, the analytical device 100 is covered on both sides except for the second flow channel chamber 2 and portions of the lead wires 8a and 8b. The cover 9 is a laminate film made of a PET film and an acrylic adhesive. The cover 9 on one side of the porous substrate S1, on both sides of which the cover 9 is provided, has an opening 9a for introducing the sample, which is connected to the second flow channel chamber 2. In order to connect the lead wires 8a and 8b to a measurement unit for measurement, which will be described later, the portions of the lead wires 8a and 8b are also processed so that they are not covered by the cover. However, the connection between the measurement unit and each electrode may be different.

[0033] <Electrode formulation> The electrode formulation in Example 1 will be described. A reference electrode 5 using Ag / AgCl was provided in the first flow path chamber 1. Furthermore, 3.5 mg of ion crystals 7, which were KCl ion crystals, were placed on the reference electrode 5. The material of the ion crystals 7 is not limited to KCl ion crystals as long as it contains Cl ions, and ions such as NaCl may also be used. The mass of the ion crystals 7 placed is the amount that results in a saturated solution when the KCl ion crystals are dissolved in pure water with a volume equivalent to the volume of the first flow path chamber 1.

[0034] On the other hand, Ag / AgCl was used for the working electrode 6 of the second flow channel chamber 2, as was the reference electrode 5. As the working electrode 6, an electrode mainly made of carbon or an electrode made of a conductive polymer such as PEDOT:PSS (a dispersion of polyethylenedioxythiophene and polystyrene sulfonic acid) may also be used.

[0035] The surfaces of the reference electrode 5 and the working electrode 6 are both FeCl ３ An oxidizing liquid such as an aqueous solution is used to bond Ag with Cl (called halogenation), and the Ag is then covered with simple AgCl (called an AgCl coat).

[0036] When measuring the electrolyte concentration of a sample, an electromotive force is generated, which is generated by a shift in the following equilibrium reaction: When a blood sample is used as the specimen, the AgCl-coated electrode makes it difficult for the interfering Br ions to react with the already bonded AgCl, and therefore makes it difficult for them to contribute to the equilibrium reaction of AgCl with Ag and Cl ions shown in formula (*). Therefore, the electrode selectively generates an electromotive force according to the Cl ion concentration.

[0037] The potential of the reference electrode 5 in contact with the liquid saturated with KCl ion crystals stabilizes at a constant value, while the potential of the working electrode 6 stabilizes at a value that varies depending on the ion concentration of the analyte.

[0038] The lead wires 8a and 8b were made of Ag / AgCl (molar ratio 6:4). Because Ag is conductive, it can function as a lead wire if a certain amount of Ag is mixed in. To prevent halogenation, masking or other treatments were used to ensure conductivity.

[0039] Other ions whose concentrations are to be measured can be measured by forming an ion-selective membrane corresponding to the respective ion. For example, to measure the concentration of Na ions, a Na ion-selective membrane is formed to cover the working electrode 6. The Na ion-selective membrane can be formed from the following materials: 3.0 mass% Bis(12-crown-4) (as an ion-selective material); 0.5 mass% Potassium tetrakis(4-chlorophenyl)borate (as an anion-rejecting agent); 64.0 mass% o-nitrophenyl octyl ether (o-nitrophenyl octyl ether); and 32.5 mass% polyvinyl chloride. This results in a voltage output corresponding to the concentration of Na ions. Note that in this example, an example of a working electrode for measuring Cl ions is shown.

[0040] 1B and 1C, in this embodiment, the inlet for dropping the sample is an opening 9a provided in the cover 9, and the opening 9a is provided to follow the shape of the second flow chamber 2. In the inlet provided on the upper surface side of the analytical device 100, the area of ​​the exposed surface 6a (reaction region) of the working electrode 6 (AgCl) is 3 mm × 3 mm = 9 mm ２The AgCl coating has a thickness of 0.01 mm. As shown in FIG. 1C , a sample 11 (shown as a dotted pattern) is introduced through the opening 9a, and a droplet of the sample 11 covers the exposed surface 6a of the working electrode 6, thereby bringing the working electrode 6 and the sample 11 into sufficient contact and generating an electromotive force. Due to the hydrophobic nature of the AgCl coating on the exposed surface 6a of the working electrode 6, a portion of the sample 11 shown in FIG. 1C maintains the shape of a droplet (approximately hemispherical) on the exposed surface 6a due to tension. Meanwhile, a portion of the sample 11 that seeps from the second flow channel chamber 2 into the connecting flow channel 3 permeates through the connecting flow channel 3 to the reference electrode 5 in the first flow channel chamber 1. A sufficient amount of sample is required to stably generate an electromotive force along with the permeation phenomenon; in this example, 30 μl of sample was introduced. This amount is the amount of sample that remains as a droplet on the exposed surface 6a of the working electrode 6 from immediately after introduction until measurement. The hydrophobicity of the working electrode 6 (exposed surface 6 a) needs to be appropriate so that a droplet can be held on the exposed surface 6 a and spread out. In terms of the contact angle, a hydrophobicity of about 50° to 100° is preferable.

[0041] (Margin area for absorbing sample) As a feature of the present disclosure, a margin area 10 for absorbing droplets of sample 11 is provided on the outside of the channel wall 4 on the analytical device 100 as shown in FIG. 1A. The margin area is a porous area (a portion where no channel wall is formed) on the outside of the channel wall, and includes both the area not covered by the cover and the area covered by the cover. The area of ​​the margin area as viewed from the opening side (top side) includes the area of ​​the area covered by the cover 9, and in this example, the area of ​​the margin area 10 as viewed from the opening 9a side is set to 2 cm. ２ It was decided.

[0042] For comparison, Figure 2 shows a top view of an analytical device 200 according to the prior art before lamination. The analytical device 200 includes a porous substrate S2 on which a first flow channel chamber 21, a second flow channel chamber 22, a connecting flow channel 23, a flow channel wall 24, a reference electrode 25, a working electrode 26, ionic crystals 27, lead wires 28a and 28b, and a cover (not shown). The shape, flow channel region configuration, and electrode formulation of the analytical device 200 are similar to those of the analytical device 100 of Example 1, except that it does not have any margins. Like the analytical device 100, the analytical device 200 has a hydrophobic cover with an opening, but this is not shown for ease of explanation. In Figure 2, the portion covered with the ionic crystals 27 is indicated by a dotted line.

[0043] The analytical device 200 according to the prior art shown in Figure 2 does not have a marginal area and is unable to absorb any sample that has not been absorbed into the flow path area. Unlike the analytical device 200 shown in Figure 2, the analytical device according to the present disclosure shown in Figures 1A to 1D has a marginal area 10, which allows the analytical device 100 to absorb any sample remaining on the analytical device 100 and allows it to be safely disposed of without contaminating the surrounding area.

[0044] -Features and Effects of this Example- In this example, the area of ​​the flow channel region is set to 4 cm ２ The area of ​​the flow channel region is the area of ​​the flow channel region (first flow channel chamber, second flow channel chamber, and connecting flow channel) surrounded by the flow channel wall as viewed from the opening side (the top side where the sample is introduced). This area includes the area covered by the cover as well as the area not covered by the cover. If electrodes or other components are present inside, the area also includes the area of ​​the porous portion below them. The area of ​​the flow channel region is related to the sample volume and is set to a size that allows a predetermined sample volume to fill the flow channel region. Due to variations in the area of ​​the flow channel region and variations in the sample volume, the sample volume may exceed the amount that can be filled into the flow channel region. Furthermore, when the sample is introduced onto the exposed surface of a hydrophobic working electrode and retained on the exposed surface, the sample remains on the exposed surface of the working electrode even after the measurement is completed. The sample volume is set to an amount that takes this into account, and the sample is introduced and measured. The larger the flow channel region to be filled with the sample, the larger the sample volume to be introduced, and the larger the sample volume tends to remain on the surface of the analytical device after the measurement. According to this example, the area of ​​the margin required to absorb the sample droplets can be estimated from the area of ​​the flow channel region.

[0045] In this embodiment, the area of ​​the margin for absorbing the sample is set to be the area of ​​the margin as seen from the opening side (the top surface side where the sample is introduced) ≧ the area of ​​the flow path region as seen from the opening side (the top surface side where the sample is introduced) × 0.50.

[0046] To be precise, the sample filling volume in the marginal area is set to be 50% or more of the sample filling volume in the flow path area, but in this embodiment, since the thickness and porosity of the porous area (flow path area and marginal area) are the same, this can be expressed by comparing the areas.

[0047] In this embodiment, the area of ​​the flow path region is 4 cm ２ This requires 30 μl of sample, of which about 10 μl cannot be adequately retained within the flow path area, and there is a risk of contaminating the surrounding area when the analytical device is discarded.

[0048] As a result of the experiment, the amount of sample that can be absorbed in the porous portion per unit area was 5 μl / cm ２ Therefore, at least 2 cm ２ The wider the margin, the greater the margin for sample absorption. However, there is a trade-off with increasing the size of the analytical device, so the optimum area is selected. In this case, 2 cm, which corresponds to 50% of the area of ​​the flow path region, is used. ２ A margin was provided.

[0049] See FIG. 1D , which is a perspective view of the analytical device 100 according to this example. In FIG. 1D , the portion covered by the cover 9 is omitted. As shown in FIG. 1D , an absorbent section 12, which is a region not covered by the cover 9, is provided in the marginal section 10. FIG. 3 is a cross-sectional view showing a method for exposing a porous section (the region not covered by the cover 9, i.e., the absorbent section 12) by exposing a portion of the marginal section 10 of the analytical device 100 according to this example. FIG. 3 shows the analytical device 100 in a state before the absorbent section 12 is exposed. Most analytical device covers according to conventional technology cover the side surfaces of the analytical device. In this example, the marginal section 10 is exposed as the absorbent section 12 by, for example, cutting the portion of the cover 9 covering the side surface of the analytical device 100 (here, this refers to the surface approximately perpendicular to the opening 9 a) along the dotted line in FIG. 3 . This allows the analytical device 100 to have an area (absorbent section 12) that is not covered by the cover 9 of the margin section 10 on the side surface (surface substantially perpendicular to the opening 9a).

[0050] The sample volume is 30 μl, and the area of ​​the flow path region is 4 cm ２ However, when the amount of sample is large, for example, when 90 μl of sample is introduced and measured, the area of ​​the flow channel region is tripled to 12 cm ２ In this case, too, if the area of ​​the margin as viewed from the opening side of the cover is 50% or more of the area of ​​the flow path region as viewed from the opening side of the cover, the sample can be absorbed with ease.

[0051] In particular, when an analytical device is used in which a working electrode is present in the introduction section and the contact angle of the exposed surface (reaction area) of the working electrode is 50° or more, the sample remains on the working electrode, and therefore contamination by the sample can be reduced by configuring the analytical device according to the present disclosure.

[0052] <Electrolyte Concentration Measurement Method> An electrolyte concentration measurement method according to one embodiment of the present disclosure is a method for measuring electrolyte concentration using an analytical device according to the present disclosure, and includes the steps of introducing a sample into the analytical device to measure the electrolyte concentration and transporting the analytical device after measurement to a disposal position provided with a disposal unit, in which the first analytical device after measurement that was transported earlier and the second analytical device after measurement that was transported later are arranged in the disposal unit so that the opening of one analytical device and the uncovered area of ​​the margin of the other analytical device are in contact or close proximity. The disposal unit refers to, for example, a trash can for disposing of analytical devices, and may be a part of the analytical device or a separate component from the analytical device.

[0053] In this example, a procedure for manually moving an analytical device, measuring electromotive force, and measuring electrolyte concentration is described. FIGS. 4 and 5 are schematic diagrams illustrating a method for measuring electrolyte concentration in this example. FIG. 6 is a schematic diagram illustrating a method for disposing of an analytical device after electrolyte concentration measurement in this example. Note that in FIGS. 4 and 5, the portion covered by the cover 9 is indicated by dotted lines, and in FIG. 6, the portion covered by the cover 9 is omitted. (1) The analytical device 100 is gripped with tweezers or the like at the portion where the cover 9 is provided and placed on the measurement table 202 as shown in FIG. 4. The electrode 203 of the measurement unit 201 for measuring electromotive force is connected to the lead wire 8a of the reference electrode 5 and the lead wire 8b of the working electrode 6 to prepare for electromotive force measurement. (2) As shown in FIG. 5, 30 μL of the sample 11 is collected from a sample ampule (not shown) into a dispensing syringe 204, and the entire 30 μL volume is dripped into the inlet (opening 9a) of the analytical device 100. (3) In this embodiment, the introduction section and the working electrode 6 are integrated, and the reference electrode 5 is wetted with the sample 11 from the second flow path chamber 2 around the working electrode 6, through the connecting flow path 3, and the first flow path chamber 1. Then, time is allowed to elapse (60 seconds after dropping in this embodiment) until the equilibrium reaction (the above formula (*)) that generates an electromotive force between the working electrode 6 and the reference electrode 5 stabilizes. (4) The measurement unit 201 prepared in (1) records the electromotive force value after 60 seconds and converts it into the actual ion concentration. (5) As shown in FIG. 6 , after measurement, the analytical device 100 is again grasped with tweezers or the like and disposed of in the disposal box 205, which is the disposal section. The operator carries the analytical device 100 to the disposal position 206, for example, directly above the disposal box 205, and drops the analytical device 100 into the disposal box 205. The analytical device 100 (first analytical device) that has been carried earlier and the analytical device 100 (second analytical device) that has been carried later are stacked in the disposal box 205. The exposed absorption section 12 (porous section) of one analytical device 100 comes into contact with the droplets of sample 11 on the other analytical device 100 (indicated by the dotted circle), and the droplets of sample 11 are absorbed.

[0054] As a result, an analytical device in which the specimen is less likely to accumulate at the bottom of the disposal section and is less likely to scatter to the outside, and an electrolyte concentration measuring method using the same, have been implemented.

[0055] Example 2 An analytical device according to another embodiment of the present disclosure is an analytical device having a porous substrate formed of a porous material, wherein a flow path wall is formed inside the porous substrate from a hydrophobic material, and the porous substrate is divided by the flow path wall into a flow path region surrounded by the flow path wall and a margin portion existing outside the flow path wall, the flow path region has a first flow path chamber, a second flow path chamber, and a connecting flow path connecting the first flow path chamber and the second flow path chamber, the first flow path chamber has a reference electrode, and the second flow path chamber has a working electrode, the working electrode containing a hydrophobic material, and hydrophobic covers are provided on both sides of the porous substrate, and the covers are provided with an opening for introducing a sample, which is connected to the second flow path chamber, and the covers are provided so as to cover at least the flow path region except for the opening, and the area of ​​the margin portion viewed from the opening side is A mm ２ The thickness of the margin is T mm, the porosity of the margin is P, and the amount of the sample introduced is S mm ３ In this case, the analytical device satisfies the relational expression A×T×P≧S×0.33, and the marginal portion has an area that is not covered by the cover.

[0056] In this example, an example is shown in which the area of ​​the marginal portion that absorbs droplets of sample is estimated according to the amount of sample introduced. The area of ​​the marginal portion will be described below using the analytical device 100.

[0057] The amount of sample required for testing is determined by the measurement item and measurement method, but when the sample amount is large, the area of ​​the flow path region and the area of ​​the required margin also increase proportionally, so the area of ​​the required margin can be estimated from the amount of sample introduced. In addition, by taking into account the thickness and porosity of the margin, the area of ​​the margin can be estimated more accurately.

[0058] (Marginal Area for Absorbing Sample) -Features and Effects of This Embodiment- A marginal area 10 for absorbing the sample is provided, as in the first embodiment. This embodiment shows the relationship between the amount of sample and the area of ​​the marginal area, etc.

[0059] The area of ​​the margin seen from the opening side (the top side where the sample is introduced) is A mm ２, the thickness of the marginal part is T mm, the porosity of the marginal part is P, and the amount of the sample introduced is S mm ３ (=μl), the following relational expression is satisfied: A×T×P≧S×0.33.

[0060] A specific calculation example is shown below. In this example, 30 μl of sample is dropped. With the area of ​​the flow path region expected in an analytical device used to measure this amount of sample, about 10 μl of this cannot be sufficiently retained within the porous substrate S1 of the analytical device 100, and there is a risk of contaminating the surrounding area when the analytical device 100 is discarded. It can be estimated that the amount of sample to be absorbed is 33% or more of the amount of sample introduced. In this example, the thickness T of the marginal portion 10 (porous substrate S1) of the analytical device 100 is 0.1 mm, and the porosity P is 0.5. By modifying A×T×P≧S×0.33 and substituting the numerical values, we obtain A≧S×0.33 / (T×P) A≧30 mm ３ x 0.33 / (0.1mm x 0.5) From the above, approximately 200mm ２ It can be estimated that a margin area of ​​1000 mm will be required.

[0061] Example 3 An analytical device according to another embodiment of the present disclosure is an analytical device having a porous substrate formed of a porous material, wherein a flow path wall is formed inside the porous substrate from a hydrophobic material, and the porous substrate is divided by the flow path wall into a flow path region surrounded by the flow path wall and a margin portion existing outside the flow path wall, the flow path region has a first flow path chamber, a second flow path chamber, and a connecting flow path connecting the first flow path chamber and the second flow path chamber, the first flow path chamber has a reference electrode, and the second flow path chamber has a working electrode, the working electrode including a hydrophobic material, and hydrophobic covers are provided on both sides of the porous substrate, and the covers are provided with an opening for introducing a sample, which is connected to the second flow path chamber, and the covers are provided so as to cover at least the flow path region except for the opening, and a maximum volume of a droplet of the sample remaining on an exposed surface of the working electrode at the opening is defined as V ｍａｘ mm ３ , the area of ​​the margin seen from the opening side is A mm ２ , the thickness of the marginal portion is T mm, and the porosity of the marginal portion is P, then V ｍａｘThe analytical device is characterized in that it satisfies the relational expression of ≦A×T×P, and the marginal portion has an area that is not covered by the cover.

[0062] This example shows an example of estimating the required area of ​​the margin 10 for the analytical device 100 from the relationship between the maximum volume of the sample droplet remaining on the exposed surface of the working electrode (corresponding to the size of the exposed surface 6a (reaction region) of the working electrode 6) and the required area of ​​the margin 10. This can be said to be a more accurate estimation than Examples 1 and 2.

[0063] (Margin area for absorbing sample) - Features and effects of this embodiment - As in embodiments 1 and 2, a margin area 10 is provided for absorbing the sample 11, but in this embodiment, the area of ​​the margin area 10 can be estimated from the volume of the droplet of sample 11 remaining on the working electrode 6.

[0064] When the analyte 11 is introduced onto the exposed surface 6a of the hydrophobic working electrode 6, and part of the analyte 11 permeates the flow path region and part of it is retained as droplets on the exposed surface 6a of the working electrode 6, droplets of the analyte 11 remain on the exposed surface 6a of the working electrode 6 even after the measurement is completed. These droplets of the analyte 11 remaining on the exposed surface 6a are the main target to be absorbed by the analytical device 100 (they are likely to contaminate the surrounding area when disposed of, etc.).

[0065] Furthermore, the amount of analyte 11 remaining on the exposed surface 6a of the working electrode 6 is related to the size and contact angle of the exposed surface 6a of the working electrode 6. Furthermore, the contact angle also changes depending on the properties of the analyte. If the analyte is water-soluble, the amount of analyte remaining is greatest when the contact angle is greatest. In other words, the maximum volume V of the droplet of analyte 11 remaining on the exposed surface 6a of the working electrode 6 can be calculated from the contact angle of the exposed surface 6a of the working electrode 6. ｍａｘ (mm ３ ) can be calculated.

[0066] Four calculation examples are shown below. Two examples are shown: one where the exposed surface 6a of the working electrode 6 at the opening 9a is circular, and the other where it is square. For each example, the contact angle of a droplet of analyte 11 on the exposed surface 6a is 100° and the other where it is 90°. The contact angle refers to the angle formed between a droplet of liquid dropped on a solid surface and the solid surface, and can be determined by, for example, the A half-angle method (θ / 2 method) or the tangent method.

[0067] (When the exposed surface of the working electrode is circular and the contact angle is 100°) The volume of the droplet of analyte 11 remaining on the exposed surface 6a of the working electrode 6 at the opening 9a is determined in relation to the area and contact angle of the exposed surface 6a of the working electrode 6. First, the maximum volume of the droplet of analyte 11 remaining on the exposed surface 6a of the working electrode 6 will be described when the contact angle θ of the hydrophobic exposed surface 6a is 100°. FIG. 8 shows a perspective view of the analytical device 100 when the analyte 11 is introduced, FIG. 9A shows a top view of the analytical device 100 before the introduction of the analyte 11, and FIG. 9B shows a top view of the analytical device 100 after the introduction of the analyte 11. In this example, the second flow chamber 2 is approximately circular, and the exposed surface 6a (reaction area) of the working electrode 6 in the second flow chamber 2 is also approximately circular. The opening 9a of the cover 9 has the same shape as the second flow chamber 2. Since the configurations of the second flow chamber 2, the working electrode 6, and the opening 9a are the same as those of Example 1, description thereof will be omitted.

[0068] In this embodiment, when a droplet of analyte 11 is introduced, the circular exposed surface 6a is in a stable state when covered with a spherical droplet having a bottom surface of the same shape as the circular exposed surface 6a, as shown in Figures 9A and 9B, and the volume of the droplet of analyte 11 remaining on the exposed surface 6a at this time is at its maximum. Figure 7 shows a simplified view of the droplet of analyte 11 remaining on the exposed surface 6a of the working electrode 6. The droplet shape parameters are 2r (mm) for the diameter of the droplet, h (mm) for the height, and V for the volume. ｍａｘ (mm ３ ), and the contact angle is θ (°). In this example, the radius of the circle of the exposed surface 6a of the working electrode 6 is 1.5 mm.

[0069] Assuming that the droplet is a part of a sphere, the diameter r of the droplet is x (mm ２), then r = (√x) / (√π).

[0070] The following equation is obtained from the A half-angle method, which is generally used to measure the contact angle.

[0071] Since tan 50° = 1.19, we can express it as h = 1.19 x r.

[0072] The volume of a part of a sphere, the spherical cap, is expressed by the following equation:

[0073] Eliminating h and r and expressing it using x, we get This can be expressed as:

[0074] In addition, when it is assumed that droplets are absorbed by the marginal portion (porous portion), the absorption capacity differs depending on the thickness and porosity of the marginal portion, and the thicker and the larger the porosity, the better the absorption of the marginal portion (porous portion). The maximum volume of the droplet of the sample remaining on the exposed surface of the working electrode is defined as V. ｍａｘ (mm ３ ), the area of ​​the margin is A (mm ２ ), the thickness of the margin is T (mm), and the porosity is P, ｍａｘ If the following expression is satisfied, the droplets of the specimen 11 can be sufficiently absorbed. From the expressions (1) and (2), the area A of the required margin is This can be expressed as:

[0075] In this example, the thickness T of the marginal portion 10 is 0.1 mm, the porosity P is 0.5, and the area of ​​the exposed surface 6a of the working electrode 6 is 1.5×1.5×π mm ２ Therefore, the area x of the exposed surface 6a of the working electrode 6 is 7.1 mm ２ From equation (1), the volume of the droplet V ｍａｘ = 9.3 mm ３ The volume of the sample actually introduced is 30 μl = 30 mm ３ and the volume of the droplet V ｍａｘ 30-9.3 mm excluding ３ The amount of the sample remaining on the exposed surface 6a of the working electrode 6 can be measured by sucking it up with a pipette.

[0076] The area A required for the margin 10 is approximately 185 to 186 mm according to formula (3). ２ This is all, and by ensuring this, excess sample droplets can be absorbed.

[0077] (When the exposed surface of the working electrode is circular and the contact angle is 90°) An example will be shown in which the contact angle of the exposed surface 6a of the working electrode 6 is 90°. In this example, as in the previous example, the exposed surface 6a of the working electrode 6 is circular with a radius of 1.5 mm. As in the previous example, refer to Figures 8, 9A, and 9B. The shape of a stable droplet of analyte 11 (a droplet of analyte 11 remaining on the exposed surface 6a of the working electrode 6) has a contact angle of 90°, so it has half the volume of a sphere with the same radius as the exposed surface 6a of the working electrode 6, and at this time, the volume of the droplet of analyte 11 remaining on the exposed surface 6a is maximum. This is half the volume of a sphere with a radius of 1.5 mm.

[0078] Therefore, the volume V of the droplet is the area of ​​the exposed surface 6a of the working electrode 6 x (mm ２ ) and This can be expressed as:

[0079] Hereinafter, as in the previous example, the maximum volume of the droplet of sample remaining on the exposed surface of the working electrode is defined as V ｍａｘ (mm ３ ), the area of ​​the margin is A (mm ２ ), the thickness of the margin is T (mm), and the porosity is P, ｍａｘ If the following expression (2) is satisfied, the droplets can be absorbed sufficiently.

[0080] From the formula (4) and the formula (2), the area A of the required margin is This can be expressed as:

[0081] In this example, the thickness T of the marginal portion 10 is 0.1 mm, the porosity P is 0.5, and the area of ​​the exposed surface 6a of the working electrode 6 is 1.5×1.5×π mm ２ Therefore, the area x of the exposed surface 6a of the working electrode 6 is 7.1 mm ２ , droplet volume V = 7.1 mm ３ The volume of the sample actually introduced is 30 μl = 30 mm ３ 30-7.1 mm excluding the volume V of the droplet ３The area A required for the margin 10 is approximately 141 mm ２ This is all, and by ensuring this, excess sample droplets can be absorbed.

[0082] (When the exposed surface of the working electrode is square and the contact angle is 100°) An example in which the exposed surface 6a of the working electrode 6 is square is shown. Fig. 10 is a perspective view of the analytical device 100 when the sample 11 is introduced, Fig. 11A is a top view of the analytical device 100 before the sample is introduced, and Fig. 11B is a top view of the analytical device 100 after the sample is introduced. In this example, the second flow channel chamber 2 is approximately square, and the exposed surface 6a (reaction area) of the working electrode 6 in the second flow channel chamber 2 is also approximately square. The opening 9a of the cover 9 has the same shape as the second flow channel chamber 2. The other parts are the same as those in Example 1, and therefore description thereof will be omitted.

[0083] When the exposed surface 6a of the working electrode 6 is square, if a sufficient amount of analyte 11 is introduced, the bottom of the droplet of analyte 11 remaining on the exposed surface 6a of the working electrode 6 will be the inscribed circle of the square, and the volume of the droplet of analyte 11 remaining on the exposed surface 6a will be maximum. As in the above example, as shown in Figure 7, the radius of the droplet of analyte 11 remaining on the exposed surface 6a of the working electrode 6 will be r, the height will be h, and the volume will be V. ｍａｘ , the contact angle is θ, and the droplet is assumed to be a part of a sphere. The diameter of the droplet 2r is calculated by dividing the square area of ​​the exposed surface 6a of the working electrode 6 by y (mm ２ ) then 2r = √y.

[0084] As above, the following equation is obtained from the A half-angle method, which is generally used to measure contact angles. Since tan 50° = 1.19, we can express it as h = 1.19 x r.

[0085] The volume of a part of a sphere, the spherical cap, is expressed by the following equation:

[0086] Eliminating h and r and expressing it using y, This can be expressed as:

[0087] Similarly to the previous example, the volume of the sample droplet remaining on the exposed surface of the working electrode is V ｍａｘ (mm ３), the area of ​​the margin is A (mm ２ ), the thickness of the margin is T (mm), and the porosity is P, ｍａｘ If the following formula (2) is satisfied, the droplets can be sufficiently absorbed. Therefore, the required area A of the margin 10 is This can be expressed as:

[0088] In this example, the thickness T of the marginal portion 10 is 0.1 mm, the porosity P is 0.5, and the area of ​​the exposed surface 6a of the working electrode 6 is 3×3 mm ２ Therefore, the area y of the exposed surface 6a of the working electrode 6 is 9 mm ２ From equation (6), the volume of the droplet V ｍａｘ = 9.3 mm ３ The volume of the sample actually introduced is 30 μl = 30 mm ３ and the volume of the droplet V ｍａｘ 30-9.3 mm excluding ３ The sample is used for permeation in the flow path area. The area A required for the margin 10 is approximately 186 mm ２ By ensuring this, excess droplets of the specimen 11 can be absorbed.

[0089] (When the exposed surface of the working electrode is square and the contact angle is 90°) As in the above example, an example is shown in which the exposed surface 6a of the working electrode 6 is square. As in the previous example, reference is made to FIGS. 10, 11A, and 11B. When the exposed surface 6a of the working electrode 6 is square, if a sufficient amount of analyte 11 is dropped, the bottom surface of the droplet of analyte 11 remaining on the exposed surface 6a of the working electrode 6 forms an inscribed circle of the square, and at this time, the volume of the droplet of analyte 11 remaining on the exposed surface 6a of the working electrode 6 is maximized. In this case, since the contact angle is 90°, the shape of the droplet is half the radius of the inscribed circle of the square. In other words, the volume is half the volume of a sphere with a radius of 1.5 mm.

[0090] Therefore, the area of ​​the exposed surface 6a of the working electrode 6 is defined as y mm ２ Then, the maximum volume V of the droplet of the sample 11 remaining on the exposed surface 6 a of the working electrode 6 is ｍａｘ teeth This can be expressed as:

[0091] Similarly to the previous example, the volume of the sample droplet remaining on the exposed surface of the working electrode is V ｍａｘ (mm３ ), the area of ​​the margin is A (mm ２ ), the thickness of the margin is T (mm), and the porosity is P, ｍａｘ If the following formula (2) is satisfied, the droplets can be absorbed sufficiently. Therefore, the required area A of the margin is This can be expressed as:

[0092] In this example, the thickness of the marginal portion 10 is 0.1 mm, the porosity is 0.5, and the area of ​​the exposed surface 6a of the working electrode 6 is 3×3 mm ２ Therefore, the area y of the exposed surface 6a of the working electrode 6 is 9 mm ２ From equation (8), the volume of the droplet V ｍａｘ = 7.1 mm ３ The volume of the sample actually introduced is 30 μl = 30 mm ３ and the volume of the droplet V ｍａｘ 30-7.1 mm excluding ３ The area A required for the margin 10 is approximately 141 mm ２ By ensuring this, excess specimen 11 can be absorbed.

[0093] Example 4 An electrolyte concentration measurement method according to one embodiment of the present disclosure is a method for measuring an electrolyte concentration using an analytical device according to the present disclosure, comprising the steps of introducing a sample into the analytical device to measure the electrolyte concentration, and transporting the analytical device after measurement to a disposal position provided with a disposal unit, and is characterized in that after the measurement step, the method comprises at least one of the following steps (i) to (iii): (i) before transporting the analytical device to the disposal position, tilting the analytical device by 30 to 80 degrees with respect to a direction horizontal to the ground so that an area not covered by the marginal cover is present below the opening, (ii) during transporting the analytical device to the disposal position, tilting the analytical device by 30 to 80 degrees with respect to a direction horizontal to the ground so that an area not covered by the marginal cover is present below the opening, and (iii) after transporting the analytical device to the disposal position, tilting the analytical device by 30 to 80 degrees with respect to a direction horizontal to the ground so that an area not covered by the marginal cover is present below the opening.

[0094] In this example, a method for recovering droplets more reliably is proposed. Unless otherwise specified, the same applies as in Example 1.

[0095] <Differences in analytical device shape> The analytical device according to the present disclosure can be an analytical device having an area on the same surface as the surface provided with the opening that is not covered by the marginal cover. Figures 12A to 12D show schematic diagrams of an analytical device 300 according to this example. Figure 12A is a top view of the analytical device 300 before lamination, Figure 12B is a top view of the analytical device 300 after lamination, Figure 12C is a cross-sectional view taken along line BB' shown in Figure 12B, and Figure 12D is a perspective view of the analytical device 300.

[0096] The analytical device 300 has a porous substrate S3 on which a first flow path chamber 31, a second flow path chamber 32, a connecting flow path 33, a flow path wall 34, a reference electrode 35, a working electrode 36, an ion crystal 37, lead wires 38a and 38b, a margin 30, and a cover 39 are formed. An opening 39a is provided in the cover 39, and an exposed surface 36a of the working electrode 36 is exposed. The shape of the analytical device 300, the configuration of the flow path region, and the electrode formulation are the same as those of the analytical device 100 of Example 1, except for the shape of the absorption section, and therefore will not be described again.

[0097] By changing the shape of the cover 39, the shape of the absorption section 312 is changed from that of Example 1. The area of ​​the marginal portion is the same as that of Example 1, and a portion of one side of the analytical device 300 (in this example, the top surface where the opening 39a for introducing the sample is provided) is left exposed and not covered with laminate, forming the absorption section 312. In this example, the cover 39 is positioned to one side, and the absorption section 312 is positioned to the other side. As in Example 1, the porous portion (the area of ​​the marginal portion 30 not covered by the cover 39) provided on the side of the analytical device 300 as the absorption section 312 can also absorb droplets of the sample 11. Note that in Figures 12A and 12B, the portions covered with the ion crystals 37 and the cover 39 are indicated by dotted lines, and in Figure 12D, the portion covered by the cover 39 is not shown.

[0098] Alternatively, the lamination method may be such that the margin surrounds the periphery of the cover. An analytical device 400 having a margin surrounding the periphery of the cover is shown in FIGS. 13A to 13D. FIG. 13A is a top view of the analytical device 400 before lamination, FIG. 13B is a top view of the analytical device 400 after lamination, FIG. 13C is a cross-sectional view taken along line CC' in FIG. 13B, and FIG. 13D is a perspective view of the analytical device 400. The analytical device 400 includes a porous substrate S4, a first flow channel chamber 41, a second flow channel chamber 42, a connecting flow channel 43, a flow channel wall 44, a reference electrode 45, a working electrode 46, an ion crystal 47, lead wires 48a and 48b, a margin 40, and a cover 49. An opening 49a is provided in the cover 49, exposing the exposed surface 46a of the working electrode 46. An absorption section 412 is provided surrounding the periphery of the cover 49. As in Example 1, the porous portion (the region of the margin portion 40 not covered by the cover 49) provided on the side of the analytical device 400 as the absorption portion 412 can also absorb droplets of the specimen 11. The shape of the analytical device 400, the configuration of the flow path region, and the electrode formulation are the same as those of the analytical device 100 of Example 1, except for the shape of the absorption portion. Note that in Figures 13A and 13B, the portions covered by the ion crystals 47 and the portions covered by the cover 49 are indicated by dotted lines, and in Figure 13D, the portions covered by the cover 49 are not shown.

[0099] <Differences in Electrolyte Concentration Measurement Method> See Figures 14 and 15. After measuring the electromotive force as in Example 1, the laminated portion of the analytical device is grasped with tweezers and tilted diagonally. This allows droplets to flow onto the exposed margin (absorbent portion) not covered by the cover, allowing the sample to be absorbed by the absorbent portion. In Figures 14 and 15, the droplets of sample 11 flow in the direction of the arrow and are absorbed, for example, in the area surrounded by the dotted circle. As shown in Figure 14, if the absorbent portion 312 is tilted, the sample can be easily absorbed even if the tilt is steep. As shown in Figure 15, if the absorbent portion 412 is shaped to surround the droplet of sample 11, absorption is possible regardless of the tilt direction. The appropriate angle can be selected based on the advantages. In this example, it is preferable to tilt the analytical device 30 to 80 degrees relative to the horizontal direction. An angle of 30 degrees or more relative to the horizontal direction facilitates sample flow, while an angle of 80 degrees or less facilitates absorption. Finally, the analytical device is carried to the disposal position and disposed of in a disposal box, which is the disposal section, to complete the measurement. In this case, the disposal position can be, for example, directly above the disposal box. This allows the sample to be disposed of in a state where it has been sufficiently absorbed.

[0100] [Example 5] In this example, a method for more efficiently collecting droplets of a specimen is proposed. Unless otherwise specified, the same as in Example 1.

[0101] <Difference in Shape of Analytical Device> An analytical device according to one embodiment of the present disclosure may be an analytical device having an area on the side opposite to the side on which the opening is provided that is not covered by a marginal cover. In this case, the analytical device may be one in which at least a portion of the same side as the side on which the opening is provided and the side opposite to the side on which the opening is provided are not covered by a cover.

[0102] In this example, the shape of the absorption section (the area of ​​the marginal portion not covered by the cover) is changed from that of Example 1. See FIGS. 16A to 16D. FIG. 16A is a top view of the analytical device 500 before lamination, FIG. 16B is a top view of the analytical device 500 after lamination, FIG. 16C is a cross-sectional view taken along the line D-D' in FIG. 16B, and FIG. 16D is a perspective view of the analytical device 500. The analytical device 500 includes a porous substrate S5 on which a first flow channel chamber 51, a second flow channel chamber 52, a connecting flow channel 53, a flow channel wall 54, a reference electrode 55, a working electrode 56, an ion crystal 57, lead wires 58a and 58b, a cover 59, and a marginal portion 50 are formed. An opening 59a is provided in the cover 59, exposing the exposed surface 56a of the working electrode 56. An absorption section 512 is provided surrounding the periphery of the cover 59. As in Example 1, the porous portion (the region of the margin portion 50 not covered by the cover 59) provided on the side of the analytical device 500 as the absorbing portion 512 can also absorb droplets of the specimen 11. The shape of the analytical device 500, the configuration of the flow path region, and the electrode formulation are the same as those of the analytical device 100 of Example 1, except for the shape of the absorbing portion.

[0103] The area of ​​the marginal portion is the same as in Example 1, and part of the marginal portion 50 on the surface of the analytical device 500 is exposed and not covered with the cover 59 on both sides (the same side as the side on which the opening 59a is provided and the opposite side) to form the absorption portion 512.

[0104] <Differences in Electrolyte Concentration Measurement Method> After measuring the electromotive force as in Example 1, the cover 59 of the analytical device 500 is grasped with tweezers, and the analytical device 500 is carried to the disposal position 206 as shown in FIG. 17, where it is disposed of in a disposal box 205, completing the measurement. As shown in FIG. 17, the analytical devices 500 overlap each other when disposed of. For this reason, by providing areas (absorption sections 512) on both sides that are not covered by the cover 59, the opportunities for absorbing droplets of sample 11 on another analytical device 500 are increased compared to Example 1 (examples of absorption locations are shown with dotted circles). This allows the analytical device to efficiently absorb the sample, improving safety during disposal.

[0105] Example 6 An analytical apparatus according to an embodiment of the present disclosure may include an analytical device according to the present disclosure, a measurement unit connected to the analytical device, which measures the electromotive force based on the potential difference between the reference electrode and the working electrode to measure the electrolyte concentration of the sample, and a disposal unit that transports the analytical device to a disposal position after measurement. The disposal unit may be, for example, a conveying member such as an arm or a belt. The disposal unit may be capable of tilting the analytical device by 30 to 80 degrees relative to a direction horizontal to the ground so that an area not covered by the marginal cover is present below the opening.

[0106] In Examples 1, 4, and 5, a method for manually moving and disposing of an analytical device with a modified absorption section was described. As another example, an example of a method for automatically moving an analytical device is shown. In this example, the analytical device 300 described in Example 4 (FIGS. 12A to 12D) is used. Hereinafter, the other configurations are the same as in Example 4 unless otherwise specified.

[0107] 18, the analytical device A1 according to this embodiment has a belt 207 as a disposal unit that carries the analytical device 300 after measurement to a disposal position 206 provided with a disposal section (disposal box 205). When carrying the analytical device 300 after measurement to the disposal position 206, the belt 207 can tilt the analytical device 300 by 30 to 80 degrees with respect to a direction horizontal to the ground so that an area (absorbent section 312) not covered by the marginal cover is present below the opening 39a.

[0108] A method for measuring electrolyte concentrations using the analytical device A1 will be described with reference to Figures 18 to 20. Note that in Figures 19 and 20, the portion covered by the cover 39 is indicated by dotted lines. (1) Analytical devices 300 are stored in a stocker 208. The stocker 208 is inclined, and a roller rotatable by a drive source (not shown) is provided at the exit of the stocker 208, which feeds out the analytical devices 300 one by one. (2) The measurement stage 202 is integrated with a belt (conveying member) 207 that can be rotated by power from a drive source (not shown). In synchronization with the analytical devices 300 being fed out from the roller, the analytical devices 300 are placed on the rotatable belt 207, which is rotated and transported, and fixed to the measurement position (the belt traveling direction is indicated by an arrow in the figures). In this example, a belt is used as the transporting member, but this is not limited to a belt. (3) Next, as shown in Figures 18 and 19, the electrode 203 of the measurement unit 201 (driven in the direction of the arrow) is positioned by a drive source (not shown) to connect to the lead wires 38b and 38a of the working electrode 36 and reference electrode 35, preparing for electromotive force measurement. (4) Next, as shown in Figures 18 and 20, 30 μl of sample is collected from a sample ampule (not shown) into a drop-dispensing syringe 204 (driven in the direction of the arrow (up, down, left, and right)) by a drive source and air source (not shown), and the entire amount is dripped and introduced into the inlet (opening 39a) of the analytical device 300. After introduction, the drop-dispensing syringe 204 is retracted. For ease of explanation, the measurement unit 201 is not shown in Figure 20. In this embodiment, the inlet (opening 39a) and the working electrode 36 are integrated. The reference electrode 35 is wetted with the sample 11, which travels from the second flow path chamber 32 around the working electrode 36 through the connecting flow path 33 and the first flow path chamber 31. Then, a time is allowed to elapse until the equilibrium reaction (formula (*)) that generates an electromotive force between the working electrode 36 and the reference electrode 35 stabilizes (in this embodiment, 60 seconds are allowed after dropping). (5) The measurement unit 201 prepared in (3) records the value of the electromotive force after 60 seconds has elapsed and converts it into the actual ion concentration. After measurement, the measurement unit 201 is retracted. (6) Transport is resumed again by the measurement stage 202 equipped with the rotatable belt 207.As shown in FIG. 21A , the belt 207 is transported using, for example, a movable stage 209 (movable in the direction of the arrow) while tilted 30 to 80 degrees from a horizontal direction so that the absorption section 312 is located below the opening 39 a of the analytical device 300. By intentionally tilting the analytical device 300 as shown in FIG. 21B , droplets of the specimen 11 flow in the direction indicated by the arrow and are absorbed by the absorption section 312. The degree of tilt is determined by the degree to which the droplets spread, and in this example, it was set to 45 degrees. In this example, an angle of 30 degrees or more facilitated the droplets to flow, while an angle of 80 degrees or less facilitated absorption to keep up with the droplet flow. In this way, by bringing the droplets of the specimen 11 into contact with the absorption section 312, the analytical device 300 can absorb and collect the droplets while transporting them on the belt 207. (7) Finally, at the disposal position 206 (e.g., directly above the disposal box 205), the analytical device 300 is dropped from the belt 207 and discarded. Since the droplets of the sample were sufficiently absorbed in the above step (6), the risk of droplet scattering could be reduced.

[0109] Example 7 An electrolyte concentration measurement method according to one embodiment of the present disclosure can be a method using an analytical device according to the present disclosure, comprising the steps of introducing a sample into the analytical device to measure the electrolyte concentration and transporting the analytical device after measurement to a disposal position provided with a disposal unit, wherein the disposal unit has a sloped bottom, and the analytical device after measurement is placed in the disposal unit at an angle of 30 to 80 degrees relative to a direction horizontal to the ground so that an area not covered by the marginal cover is present below the opening. Furthermore, an analytical apparatus according to one embodiment of the present disclosure can be an analytical apparatus further including a disposal unit having a bottom surface sloped at an angle of 30 to 80 degrees relative to a direction horizontal to the ground, and the disposal unit transports the analytical device to the disposal position provided with the disposal unit.

[0110] In Example 6, the analysis device was tilted by tilting the belt, which is the disposal unit. In this example, an example in which the analysis device is tilted at an angle in the disposal unit is shown.

[0111] In this example, the analytical device 300 described in Example 4 (FIGS. 12A to 12D) is used, as in Example 6. Hereinafter, the configuration and steps of the analytical device are the same as those in Example 6 unless otherwise specified. Specifically, steps (1) to (5) of the <Electrolyte Concentration Measurement Method> described in Example 6 are performed, and then the measurement is carried out according to the changes shown below.

[0112] <Changes in the Electrolyte Concentration Measurement Method> (6) A horizontal belt 207 is used for the analytical device transport process. (An angle-adjustable belt is not required.) (7) See FIG. 22 . After the belt 207 releases the analytical device 300 at the disposal position 206 (e.g., directly above the waste box 205, which is the waste section), the analytical device 300 is adjusted so that it strikes the drop direction adjustment bar 210. This allows the analytical device 300 to fall at an angle in the direction of the arrow in the figure, so that droplets of the sample 11 are directed toward the absorption section 312. Furthermore, the bottom surface 205a of the waste box 205 is angled so that droplets of the sample 11 are directed toward the arrow in the figure. Even after the analytical device 300 lands on the bottom of the waste box 205, the droplets continue to be absorbed by the absorption section 312 (shown by the dotted circle in the figure). In this example, the angle of the bottom surface 205a is 45 degrees relative to the horizontal direction. In this example, when the angle was 30 degrees or more, the droplets of the specimen 11 easily flowed, and when the angle was 80 degrees or less, the absorption easily kept up with the flow of the droplets. This enabled the analysis device 300 to sufficiently absorb the specimen 11 and discard it.

[0113] Example 8 This example uses the analytical device described in Example 6, and shows an example of efficiently absorbing droplets using the analytical device. The analytical device used can be any of the analytical device 100 described in Example 1, the analytical device 300, analytical device 400, and analytical device 500 described in Example 4, but in this example, the analytical device 300 is used. Hereinafter, the configuration and steps of the analytical device are the same as in Example 6 unless otherwise specified. Specifically, steps (1) to (5) of the <Electrolyte Concentration Measurement Method> described in Example 6 are performed, and then the measurement is carried out with the following modifications.

[0114] <Changes in the Electrolyte Concentration Measurement Method> (6) A horizontal belt 207 is used in the transport process (a belt with adjustable angle is not necessary). Meanwhile, multiple positions (disposal positions 206) for the analytical device 300 are available from the belt 207. (7) When the belt 207 releases the analytical device 300 during disposal, the disposal position 206 is adjusted so that the absorption section 312 of the analytical device 300 to be discarded contacts droplets of the specimen 11 on another analytical device 300 that has already been discarded. In other words, the states shown in Figures 6 and 17 are realized by mechanical control of the belt 207. This allows, for example, droplets on an analytical device that has fallen earlier to be absorbed by the absorption section of an analytical device that has fallen later.

[0115] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the present disclosure. Therefore, the following claims are appended to apprise the public of the scope of the present disclosure.

[0116] This application claims priority based on Japanese Patent Application No. 2024-103860, filed June 27, 2024, the entire contents of which are incorporated herein by reference.

[0117] 1, 21, 31, 41, 51... First flow path chamber 2, 22, 32, 42, 52... Second flow path chamber 3, 23, 33, 43, 53... Connection flow path 5, 25, 35, 45, 55... Reference electrode 6, 26, 36, 46, 56... Working electrode 9, 39, 49, 59... Cover 10, 30, 40, 50... Margin portion 12, 312, 412, 512... Absorption portion

Claims

1. An analytical device having a porous substrate formed of a porous material, wherein a flow path wall is formed inside the porous substrate from a hydrophobic material, and the porous substrate is divided by the flow path wall into a flow path region surrounded by the flow path wall and a marginal portion located outside the flow path wall, the flow path region has a first flow path chamber, a second flow path chamber, and a connecting flow path connecting the first flow path chamber and the second flow path chamber, the first flow path chamber has a reference electrode, and the second flow path chamber has a working electrode, the working electrode comprising a hydrophobic material, hydrophobic covers are provided on both sides of the porous substrate, and the covers have an opening for introducing a sample that is connected to the second flow path chamber, and the covers are provided to cover at least the flow path region except for the opening, the area of ​​the marginal portion as viewed from the opening side is 50% or more of the area of ​​the flow path region as viewed from the opening side, and the marginal portion has an area that is not covered by the cover.

2. An analytical device having a porous substrate formed of a porous material, wherein a flow path wall is formed inside the porous substrate from a hydrophobic material, and the porous substrate is divided by the flow path wall into a flow path region surrounded by the flow path wall and a marginal portion existing outside the flow path wall, the flow path region has a first flow path chamber, a second flow path chamber, and a connecting flow path connecting the first flow path chamber and the second flow path chamber, the first flow path chamber has a reference electrode, and the second flow path chamber has a working electrode, the working electrode containing a hydrophobic material, and hydrophobic covers are provided on both sides of the porous substrate, and the covers are provided with an opening communicating with the second flow path chamber for introducing a sample, and the covers are provided so as to cover at least the flow path region except for the opening, and the area of ​​the marginal portion viewed from the opening side is defined as A mm ２ The thickness of the marginal portion is T mm, the porosity of the marginal portion is P, and the amount of the sample to be introduced is S mm ３ In this case, the analytical device satisfies the relational expression A×T×P≧S×0.33, and the marginal portion has an area that is not covered by the cover.

3. An analytical device having a porous substrate formed of a porous material, wherein a flow path wall is formed inside the porous substrate by a hydrophobic material, and the porous substrate is divided by the flow path wall into a flow path region surrounded by the flow path wall and a margin portion existing outside the flow path wall, the flow path region has a first flow path chamber, a second flow path chamber, and a connecting flow path connecting the first flow path chamber and the second flow path chamber, the first flow path chamber has a reference electrode, and the second flow path chamber has a working electrode, the working electrode comprising a hydrophobic material, hydrophobic covers are provided on both sides of the porous substrate, and the covers are provided with an opening communicating with the second flow path chamber for introducing a sample, the covers are provided so as to cover at least the flow path region except for the opening, and the maximum volume of a droplet of the sample remaining on the exposed surface of the working electrode at the opening is defined as V ｍａｘ mm ３ , the area of ​​the marginal portion as viewed from the opening side is A mm ２ , where the thickness of the marginal portion is T mm and the porosity of the marginal portion is P, V ｍａｘ An analytical device, characterized in that the marginal portion has an area that is not covered by the cover, and the marginal portion satisfies the relational expression of ≦A×T×P.

4. An analytical device according to any one of claims 1 to 3, characterized in that the contact angle of the exposed surface of the working electrode at the opening is 50° or more.

5. An analytical device according to any one of claims 1 to 4, characterized in that the analytical device has a side surface having an area of ​​the marginal portion that is not covered by the cover.

6. An analytical device according to any one of claims 1 to 5, characterized in that the marginal portion has an area not covered by the cover on the same surface as the surface on which the opening is provided.

7. An analytical device according to any one of claims 1 to 6, characterized in that the marginal portion has an area not covered by the cover on the side opposite to the side on which the opening is provided.

8. A method for measuring the concentration of an electrolyte using an analytical device according to any one of claims 1 to 7, comprising the steps of introducing the sample into the analytical device to measure the concentration of an electrolyte, and transporting the analytical device after measurement to a disposal position provided with a disposal section, wherein the first analytical device and the second analytical device are arranged in the disposal section so that the opening of one analytical device after measurement, which was transported earlier, and the area of ​​the marginal part of the other analytical device that is not covered by the cover, are in contact with or close to each other.

9. A method for measuring the concentration of an electrolyte using the analytical device according to any one of claims 1 to 7, comprising the steps of introducing the sample into the analytical device to measure the concentration of an electrolyte, and transporting the analytical device after measurement to a disposal position provided with a disposal unit, and comprising at least one of the following steps (i) to (iii) after the measurement step: (i) before transporting the analytical device to the disposal position, tilting the analytical device by 30 to 80 degrees with respect to a direction horizontal to the ground so that an area of ​​the marginal portion not covered by the cover is located below the opening, (ii) during the step of transporting the analytical device to the disposal position, tilting the analytical device by 30 to 80 degrees with respect to a direction horizontal to the ground so that an area of ​​the marginal portion not covered by the cover is located below the opening, and (iii) after the step of transporting the analytical device to the disposal position, tilting the analytical device by 30 to 80 degrees with respect to a direction horizontal to the ground so that an area of ​​the marginal portion not covered by the cover is located below the opening.

10. A method for measuring the concentration of an electrolyte using an analytical device according to any one of claims 1 to 7, comprising the steps of introducing the specimen into the analytical device to measure the concentration of an electrolyte, and transporting the analytical device after measurement to a disposal position provided with a disposal section, wherein the disposal section has an inclined bottom, and the analytical device after measurement is placed in the disposal section at an angle of 30 to 80 degrees relative to a direction horizontal to the ground so that an area of ​​the margin not covered by the cover is present below the opening.

11. An analytical apparatus comprising: an analytical device according to any one of claims 1 to 7; a measurement unit connected to said analytical device, which measures electromotive force based on the potential difference between said reference electrode and said working electrode, and measures the electrolyte concentration of said sample; and a disposal unit which transports said analytical device to a disposal position after measurement.

12. The analytical apparatus described in claim 11, characterized in that the disposal unit tilts the analytical device 30 to 80 degrees from a direction horizontal to the ground so that an area of ​​the margin not covered by the cover is present below the opening.

13. An analytical device as described in claim 11 or 12, further comprising a disposal section having a bottom surface inclined at 30 to 80 degrees relative to a direction horizontal to the ground, wherein the disposal unit transports the analytical device to a disposal position where the disposal section is provided.

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