Test paper and kit for detecting urea in body fluid

Abstract

A test paper and kit for detecting urea in a body fluid. The test paper comprises: a base layer (1), comprising a proximal end and a distal end extending transversely from the proximal end; a sampling zone (2), arranged at the distal end of the base layer (1) and used for absorbing a body fluid under test; a reaction zone (3), arranged on the base layer (1) and used for absorbing the body fluid from the sampling zone (2) to react with urease in the reaction zone (3); a diffusion zone (4), arranged on the base layer (1) and connected to the reaction zone (3), and used for laterally chromatographing, from the distal end towards the proximal end, a reaction product generated in the reaction zone (3); and a color development zone (5), arranged on the base layer (1) and isolated from the reaction zone (3) by means of the diffusion zone (4), and used for absorbing the laterally chromatographed reaction product from the diffusion zone (4) to carry out a color development reaction with a color development substance in the color development zone (5), so as to display a detection result of urea in the body fluid.

Description

Test paper and kit for detecting urea in body fluid TECHNICAL FIELD

[0001] The present application relates to the technical field of urea detection, and particularly relates to a test paper and kit for detecting saliva urea. BACKGROUND

[0002] Currently, the methods for detecting whether urea is contained in a liquid mainly include liquid reagent detection and test paper detection. The liquid reagent detection has the disadvantages of not being easy to save and carry, needing a special configuration support and a test tube, and being inconvenient to operate, while the test paper detection has the advantages of being convenient to carry and simple to operate.

[0003] In the related art, the test paper for detecting whether urea is contained in a liquid is mainly a longitudinal vertical test paper. The longitudinal vertical test paper includes superimposing carriers with reaction reagents on each other, and a to-be-detected liquid sample flows through each reaction reagent layer from top to bottom, and finally displays a detection result. For example, the test paper for detecting urea nitrogen disclosed in the invention patent CN106645675A is suitable for detecting whether urea nitrogen exists in blood. For another example, the urea test paper disclosed in the Chinese utility model patent CN210604396U has a urease test paper layer arranged on an upper layer of a phenol red chemical layer. If the to-be-detected liquid sample contains urea, the urease in the urease test paper layer will decompose the urea in the to-be-detected liquid sample to generate ammonia and carbon dioxide. The ammonia is easily dissolved in water and is alkaline in the aqueous solution. Under the action of gravity, the solution moves downward to the phenol red chemical layer to generate a color change reaction. The above longitudinal vertical test paper has the limitation that the reaction area and the color development area cannot be completely isolated due to the structural design, and has the limitations of short color development and reading time window.

[0004] Therefore, the detection accuracy of the current test paper mainly depends on the reading time / picture taking time of the accurate color development result. In other words, the current test paper needs to complete the reading / picture taking of the color development result immediately after the reaction is completed, and thus the test paper is limited to be used in professional scenes such as laboratories and hospitals. Therefore, how to design a urea test paper with an extended reading time window for personal users is a technical problem to be solved. SUMMARY

[0005] In view of the above-mentioned shortcomings of the related art, the purpose of the present application is to provide a test paper and kit for detecting urea in body fluid, a method and system for detecting urea in body fluid, a computer device, a computer readable storage medium, and a computer program product, to solve the technical problem of how to design a urea test paper with an extended reading time window for personal users.

[0006] To achieve the above object and other related objects, the first aspect of the present application provides a test paper for detecting urea in a body fluid, comprising: a base layer comprising a proximal end and a distal end extending laterally from the proximal end; a sampling area arranged at the distal end of the base layer for absorbing the body fluid to be detected; a reaction area arranged on the base layer for absorbing the body fluid in the sampling area to react with urease in the reaction area; a diffusion area arranged on the base layer and connected to the proximal end of the reaction area for laterally chromatographing the reaction product generated by the reaction area from the distal end to the proximal end; and a color development area arranged on the base layer and isolated from the reaction area by the diffusion area, for absorbing the reaction product laterally chromatographed by the diffusion area to develop color with color developing substances in the color development area, so as to display the detection result of urea in the body fluid.

[0007] The second aspect of the present application provides a kit for detecting urea in a body fluid, comprising: a shell having an internal space, a first window located at the distal end of the shell, and a second window away from the first window; a base layer arranged in the internal space; a sampling area arranged at the distal end of the base layer and used for absorbing the body fluid to be detected through the first window; a reaction area arranged on the base layer for absorbing the body fluid in the sampling area to react with urease in the reaction area; a diffusion area arranged on the base layer and connected to the proximal end of the reaction area for laterally transferring the reaction product of the reaction area; and a color development area arranged on the base layer corresponding to the second window and isolated from the reaction area by the diffusion area, for absorbing the reaction product laterally transferred by the diffusion area to develop color with color developing substances in the color development area, so as to display the detection result of urea in the body fluid through the second window.

[0008] The third aspect of the present application provides a method for detecting urea in a body fluid, comprising: obtaining a detection image by photographing the test paper according to the first aspect of the present application or the kit according to the second aspect of the present application using an image capturing device; wherein the detection image is photographed within a reading time window after the test paper or the kit absorbs the body fluid to be detected by a user, and the detection image includes an image of a color development area; determining color development data corresponding to the image of the color development area based on the detection image; and determining the urea concentration of the body fluid based on the color development data and a standard curve corresponding to the test paper or the kit.

[0009] The fourth aspect of the present application provides a system for detecting urea in a body fluid, comprising: an acquisition module configured to acquire a detection image obtained by photographing the test paper according to the first aspect of the present application or the kit according to the second aspect of the present application by using an image capturing device; wherein the detection image is photographed within a reading time window after the test paper or the kit absorbs the body fluid to be detected, and the detection image comprises an image of a color development zone; a color development data determination module configured to determine color development data corresponding to the image of the color development zone based on the detection image; and a concentration determination module configured to determine the urea concentration of the body fluid based on the color development data and a standard curve corresponding to the test paper or the kit.

[0010] The fifth aspect of the present application provides a computer device, comprising: a storage device configured to store at least one program; and a processing device connected to the storage device, configured to invoke the at least one program from the storage device and execute the at least one program to implement the method for detecting urea in a body fluid according to the third aspect of the present application.

[0011] The sixth aspect of the present application provides a computer-readable storage medium storing at least one program, wherein the at least one program is invoked and executed by a processor of a computer to implement the method for detecting urea in a body fluid according to the third aspect of the present application.

[0012] The seventh aspect of the present application provides a computer program product, which, when running on a computer, causes the computer to execute the method for detecting urea in a body fluid according to the third aspect of the present application.

[0013] In summary, the test paper and the kit for detecting urea in a body fluid, the method and the system for detecting urea in a body fluid, the computer device, the computer-readable storage medium, and the computer program product provided by the present application, the test paper is arranged in sequence in a transverse direction / lateral direction by arranging a sampling zone, a reaction zone, a diffusion zone, and a color development zone, so that the reaction zone and the color development zone are effectively separated by the diffusion zone in between, the diffusion zone can prevent urease in the reaction zone from entering the color development zone, so as to terminate the catalytic reaction before the reaction solution reaches the color development zone, thereby improving the stability of the color development reaction in the color development zone, and further prolonging the reading time window of the color development result of the test paper to facilitate the use of individual users. BRIEF DESCRIPTION OF DRAWINGS

[0014] The specific features involved in the present application are shown in the appended claims. The features and advantages of the application involved in the present application can be better understood by referring to the exemplary embodiments described in detail below and the accompanying drawings. A brief description of the drawings is as follows:

[0015] FIG. 1 shows a cross-sectional view of a test paper for detecting urea in a body fluid according to an embodiment of the present application.

[0016] Figure 2 shows a cross-sectional view of a test paper for detecting body fluid urea according to an embodiment of the present application.

[0017] Figure 3 shows a standard curve according to an embodiment of the present application.

[0018] Figure 4 shows a standard curve corresponding to a test paper according to a comparative example of the present application, which was prepared using a reaction reagent having a urease concentration of 65 kU / L.

[0019] Figure 5 shows a standard curve corresponding to a test paper according to a comparative example of the present application, which was prepared using a reaction reagent having a buffer concentration of 1.25 mM and a pH of 7.4.

[0020] Figure 6 shows a top view of a test kit for detecting body fluid urea according to an embodiment of the present application.

[0021] Figure 7 shows a standard curve of a test paper according to another embodiment of the present application, which has a detection range of urea concentration of 5-30 mM.

[0022] Figure 8 shows a flowchart of a method for detecting body fluid urea according to an embodiment of the present application.

[0023] Figure 9 shows a structural block diagram of a system for detecting body fluid urea according to an embodiment of the present application. DETAILED DESCRIPTION

[0024] The advantages and technical effects of the present application can be easily understood by those skilled in the art from the description of specific embodiments disclosed herein. In the following description, some embodiments can be described with reference to the accompanying drawings. It should be understood that other embodiments not depicted in the drawings can also be used, and that changes in specific structures, components or mechanisms, assemblies and operations can be made without departing from the spirit and scope of the present application. The following detailed description should not be considered as limiting, and the scope of the embodiments of the present application is only limited by the claims disclosed herein. The terms used herein are only for describing specific embodiments, and are not intended to limit the present application.

[0025] It should be understood that, although the terms first, second, or third etc. can be used herein to describe various elements or parameters, these elements or parameters should not be limited by these terms. These terms are only used to distinguish one element or parameter from another element or parameter. For example, a first window can be termed a second window, and similarly, a second window can be termed a first window without departing from the scope of the various described embodiments, both the first window and the second window are windows, but they are not the same window unless the context clearly indicates otherwise.

[0026] Also, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including", when used herein, specify the presence of stated features, steps, operations, elements, components, items, and / or groups but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, items, and / or groups thereof. For example, a process, method, system, product or apparatus that comprises a list of steps or units need not necessarily be limited to the steps or units clearly recited, but can include other steps or units that are not expressly listed or inherent to such processes, methods, products or apparatuses. In addition, the term "and / or" used in the following can be used to describe the association relationship of associated objects, which means that there can be three relationships, for example, A and / or B can represent the three cases of A existing alone, A and B existing together, and B existing alone. In addition, the character " / ", if not specially indicated, generally represents a "and / or" relationship between the front and rear associated objects. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two. Furthermore, the terms "or" and "and / or" used herein are interpreted as inclusive or mean any one or any combination. This definition is only an exception when the combination of elements, functions, steps or operations is inherently mutually exclusive in some way.

[0027] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms used herein should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0028] Relative terms such as "below" or "above" or "upper" or "lower" or "horizontal" or "vertical" can be used herein to describe a relationship of one element, layer, or region to another element, layer, or region as illustrated in the Figures. It will be understood that these terms are intended to encompass different orientations of the device in addition to the orientation depicted in the Figures. In the present application, the term "vertical", "horizontal", "parallel", are defined as including ±10% on the basis of standard definitions. For example, vertical generally means ±90° from a reference line, but in the present application, vertical means ±80° to 100°. Unless specifically stated otherwise, comparative quantitative terms such as "greater than" and "less than" are intended to encompass the concept of "equal to".

[0029] Further, the use of endpoints in the description of ranges of values of parameters (such as, for example, ranges of values for the number of endpoints) is merely intended to indicate that the range of values is inclusive of the values that are recited as the upper and lower limits of the range. Unless otherwise indicated, all numbers indicating quantities of components, molecular weights, etc. in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, numerical parameters listed in the specification and claims are approximations. At the very least, each numerical parameter should at least be construed in light of the number of significant digits it contains. Each numerical parameter should at least be construed in accordance with the number of significant digits it contains.

[0030] Notwithstanding that the numerical ranges and parameters setting forth the broadest scope of the application are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0032] As described in the background, the test paper for detecting whether urea is contained in the liquid is mostly longitudinal vertical test paper. The area of the reaction reagent carrier in the longitudinal vertical test paper is small, so the liquid sample needs to be used in a small amount, and the sample amount also has certain requirements, which cannot exceed the maximum capacity of the reaction reagent carrier. If the amount of the liquid sample added is too large, the reaction reagent layer saturated with the liquid cannot absorb the excess sample, and the excess sample will overflow the test paper, pollute the environment or contact the detector. In addition, the excess liquid will also gather on the reaction reagent layer to form droplets, which not only affects the judgment of the result by optical detection instruments, but also seriously pollutes the detection instrument. It can also cause the color developing area to be polluted by the sample, the reaction liquid to move down to the color developing area to cause the color development to be unable to terminate, the data read by the fixed reading time of the equipment to deviate from the preset standard, and thus cause inaccurate quantification.

[0033] To solve the above problems, the invention patent CN 102128918A adopts a liquid locking structure, which aims to vertically flow into the reaction reagent layer when the liquid sample is added to the sample layer. When the reaction reagent layer is saturated with the liquid, the liquid diffuses into the liquid locking component which is overlapped with the reaction reagent layer. Since the liquid absorption speed of the liquid locking component is less than or equal to the liquid absorption speed of the reaction reagent layer, when the excess liquid diffuses into the liquid locking component, the liquid on the reaction reagent layer is sufficient for the related detection reaction, so as not to affect the effective amount required for the detection reaction. When an excessive amount of sample is added, the excess sample is absorbed by the liquid locking component, so the excess sample will not form droplets and overflow outside the test paper. However, this kind of liquid locking structure is complex in process, requires the liquid absorption speed of the liquid locking component to be less than or equal to the liquid absorption speed of the reaction reagent layer, has high requirements on the material of the liquid locking component, and increases the process in the test paper production process, making the test paper production process more complex.

[0034] In addition, the MicroSlide, a hospital-end urea detection product launched by the American company Ortho Clinical Diagnostics The MicroSlide is also a longitudinal dry chemical test paper, which adopts a highly precise quantitative sampling and fixed-time reading method to ensure the accuracy of the detection. The test paper uses a precise sampling device to accurately sample 5.5 μL, and a matching dry biochemical analyzer to collect color developing data at fixed time to analyze the urea content in the sample. This method has high requirements on the test paper process and equipment precision, is only suitable for hospital-end detection products, and is not convenient for personal users to use, thereby limiting the use scenarios of the dry chemical test paper.

[0035] As described above, the enzyme kinetics method presents different enzyme kinetics curves by fixing the amount of enzyme and reaction time according to different substrate concentrations, and then reflects the change of the reaction system pH in the color development zone to realize the quantitative or semi-quantitative test method. The method is commonly used in chemical kits and reagent discs, and the above-mentioned longitudinal test strips are all designed by using this method. Whether the longitudinal test strip is designed to flow from top to bottom or migrate from bottom to top, the physical distance between the color development zone and the reaction zone cannot be significantly separated in the design level. If the enzyme kinetics quantification is to be completed after the sample passes through the reaction zone, the reaction should be theoretically terminated or the color development data should be immediately read. However, the termination of the reaction usually requires changing the pH value of the reaction system, which is contrary to the most commonly used pH indicator to indicate the reaction intensity in the dry chemical test paper. Therefore, most of the longitudinal dry chemical urea test strips cannot complete the termination of the reaction, and thus the detection accuracy depends on the accurate result collection time.

[0036] Therefore, at present, the detection accuracy of the test strip mainly depends on the reading time / picture taking time of the color development result. Specifically, the test strip currently used for detecting whether the liquid (such as blood) contains urea is arranged longitudinally between the reaction zone and the color development zone, and the interval between the two is in the order of microns, which leads to a short reading time window of the color development result, and thus it is inconvenient for individual users to use, which limits the use scenarios of the dry chemical test paper. For example, the thickness of the carrier / substrate of each layer in the current longitudinal test strip is in the order of microns, which leads to that even if the reaction zone and the color development zone are isolated in the longitudinal test strip, the interval between the reaction zone and the color development zone will remain in the order of microns due to the insufficient thickness of the isolation substrate, which affects the stability of the color development of the color development zone and leads to a short reading time window.

[0037] In view of this, in some embodiments provided in the present application, a test paper for detecting urea in body fluid is disclosed, which comprises a base layer, a sampling area, a reaction area, a diffusion area, and a color development area. The reaction area is used to absorb the body fluid in the sampling area to react with urease in the reaction area. The diffusion area is used to laterally chromatograph the reaction product generated by the reaction area from the distal end to the proximal end. The color development area is isolated from the reaction area by the diffusion area and is used to absorb the reaction product laterally chromatographed by the diffusion area to perform a color development reaction with a color development substance in the color development area to display the detection result of the urea in the body fluid. The test paper of the present application effectively separates the laterally arranged reaction area and color development area by the intermediate diffusion area. The diffusion area can prevent the urease in the reaction area from entering the color development area, and thus the diffusion area can terminate the catalytic reaction of the urease to improve the stability of the color development reaction in the color development area, so as to prolong the reading time window of the color development result in the color development area to facilitate the use of individual users.

[0038] The body fluid can be a body fluid of an animal or a body fluid of a human. Since the content of urea in the body fluid of an animal or a human has a correlation with the content of urea in blood, the content of urea in blood can be calculated by using the content of urea in the body fluid. The body fluid includes, but is not limited to, saliva, tears, sweat, urine, blood, serum, plasma, and the like.

[0039] In an embodiment, the test paper is used for detecting saliva, i.e., the test paper is used for detecting urea in saliva. Compared with collecting blood, serum, plasma, and the like to detect urea, saliva does not need to be collected in a hospital or a laboratory, and is convenient for personal users to use.

[0040] The test paper can also be referred to as a test paper strip, a reagent strip, or a detection test paper, and the test paper can display a detection result of urea in a body fluid. Specifically, the detection result can be represented by a color of a chromogenic area in the test paper, and then an image of the chromogenic area is acquired, and the image is analyzed to quantitatively calculate the content of urea by the color of the image of the chromogenic area.

[0041] In an embodiment, referring to FIG. 1, a cross-sectional view of a test paper for detecting urea in a body fluid in an embodiment of the present application is shown. As shown in the figure, the test paper for detecting urea in a body fluid includes a base layer 1, a sampling area 2, a reaction area 3, a diffusion area 4, and a chromogenic area 5. Specifically, the base layer 1 includes a proximal end and a distal end extending transversely from the proximal end, the distal end of the base layer 1 is provided with the sampling area 2 for absorbing a body fluid to be detected, the reaction area 3 is used for absorbing the body fluid in the sampling area 2 to react by using urease in the reaction area 3, the diffusion area 4 is connected with the reaction area 3 and is used for laterally chromatographing a reaction product generated by the reaction area 3 from the distal end to the proximal end, and the chromogenic area 5 is isolated from the reaction area 3 by the diffusion area 4, and is used for absorbing the reaction product laterally chromatographed by the diffusion area 4 to perform a chromogenic reaction by using a chromogenic substance in the chromogenic area 5, so as to display a detection result of urea in a body fluid.

[0042] In an embodiment, the base layer includes a proximal end and a distal end extending transversely from the proximal end. The proximal end and the distal end are opposite ends of the base layer, one end of the base layer for arranging the sampling area is referred to as the distal end of the base layer, and conversely, the other end of the base layer away from the sampling area is referred to as the proximal end of the base layer. Similarly, one side of each layer (the sampling area, the reaction area, the diffusion area, and the chromogenic area) in the test paper close to the proximal end of the base layer is also referred to as the proximal end of each layer, and conversely, the other side of each layer in the test paper away from the proximal end of the base layer is referred to as the distal end of each layer.

[0043] In an embodiment, the base layer is made of a material with a water absorption rate lower than a preset water absorption rate, so as to avoid absorbing the liquid (body fluid, reagent) in each layer (sampling area, reaction area, diffusion area, and color development area). In an example, the preset water absorption rate is 1%, 2%, 3%, or 4%. For example, the base layer is a PVC (Polyvinyl chloride) plate; further, the PVC plate is a PVC plate with adhesive. As another example, the material of the base layer is polypropylene (pp) or polyethylene (pe), etc. It should be noted that the material of the base layer is not limited to the above examples, and in other embodiments, as long as the material has a water absorption rate lower than the preset water absorption rate, it can be used as the material of the base layer.

[0044] In an embodiment, in the test paper, the size of the base layer at least needs to meet the size required for arranging the sampling area, the reaction area, the diffusion area, and the color development area. In an example, the width of the base layer is greater than or equal to the width of any one of the sampling area, the reaction area, the diffusion area, and the color development area. In an example, the length of the base layer is related to the length of each layer of the sampling area, the reaction area, the diffusion area, and the color development area, for example, the length of the base layer needs to be greater than or equal to the sum of the lengths of each layer of the sampling area, the reaction area, the diffusion area, and the color development area. In another example, when there is an overlapping area between adjacent layers (for example, the reaction area and the diffusion area), the length of the base layer is related to the length of each layer of the sampling area, the reaction area, the diffusion area, and the color development area and the size of the overlapping area of the adjacent layers.

[0045] In an embodiment, as shown in FIG. 1, the sampling area 2 is arranged at the distal end of the base layer 1 for absorbing the body fluid to be detected.

[0046] In some embodiments, the sampling area 2 can be arranged at the distal end of the base layer 1 by means of adhesion. For example, the base layer 1 is a PVC plate with adhesive, and the sampling area 2 is adhered to the adhesive side of the base layer 1. In other examples, the sampling area can also be fixed at the distal end of the base layer by means of clamping, pressing, or the like.

[0047] In some embodiments, the user can drop the body fluid to be detected on the sampling area 2 of the test paper. Taking saliva as an example, the user can use a sampling container such as a sampling tube or a dropper to directly take the body fluid to be detected from the oral cavity or a container containing the body fluid to be detected and drop it on the sampling area 2, so that the sampling area 2 absorbs the body fluid to be detected. The user can also directly immerse the sampling area 2 in a container containing the body fluid to be detected to allow the sampling area 2 to absorb the body fluid to be detected. It should be noted that the application does not limit the way the sampling area absorbs the body fluid to be detected.

[0048] For example, the user drops the body fluid to be detected on the sampling area of the test paper. In an example, the amount of the body fluid to be detected dropped on the sampling area is 50-200 μL. For example, the amount of the body fluid to be detected dropped on the sampling area is 50 μL, 60 μL, 70 μL, 80 μL, 90 μL, 100 μL, 110 μL, 120 μL, 130 μL, 140 μL, 150 μL, 160 μL, 170 μL, 180 μL, 190 μL, 200 μL.

[0049] In some embodiments, the material of the sampling area is a water-absorbing material. For example, a glass fiber membrane, a polyester fiber membrane, a water-absorbing paper, or a filter paper, etc.

[0050] In some embodiments, in the test paper, the length of the sampling area is between 15 mm and 30 mm, and the width of the sampling area is between 3 mm and 5 mm, that is, the length of the substrate of the sampling area is between 15 mm and 30 mm, and the width of the substrate of the sampling area is between 3 mm and 5 mm. For example, the length of the substrate of the sampling area is 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, or 30 mm, and the width of the substrate of the sampling area is 3 mm, 4 mm, or 5 mm.

[0051] It should be noted that the size of each layer defined in the embodiments of the present application and the cover plate described below is not the size in the manufacturing process (such as spraying or scribing), but the size of each layer and the cover plate in the final test paper. In the manufacturing process, only the size of the substrate required by each manufacturing process needs to be met.

[0052] In an embodiment, as shown in FIG. 1, the reaction area 3 is arranged on the base layer 1, and the reaction area 3 is used to absorb the body fluid in the sampling area 2 to react with urease in the reaction area 3. Specifically, the reaction area 3 is arranged on the back side / proximal end of the sampling area 2, and then the reaction area 3 can absorb the body fluid in the sampling area 2. The reaction area reacts (catalytic reaction) with urease in the reaction area and urea in the body fluid to produce ammonia, and then obtains a reaction product (which can also be referred to as a reaction liquid) including ammonia ions.

[0053] In some embodiments, the reaction area 3 can be arranged on the base layer 1 by pasting. For example, the base layer 1 is a PVC plate with adhesive on the back, and the reaction area 3 is pasted on the back of the base layer 1. In other examples, the reaction area 3 can also be fixed on the base layer by clamping, pressing, or other fixing methods.

[0054] The reaction reagent is configured on the substrate of the reaction zone. In some embodiments, the reaction reagent can be configured on the substrate of the reaction zone by scribing or sputtering. For example, the reaction reagent is uniformly scribed on the substrate of the reaction zone by scribing sputtering instrument. For another example, the reaction reagent is uniformly sputtered on the substrate of the reaction zone by scribing sputtering instrument. Further, after the reaction reagent is configured on the substrate of the reaction zone, drying treatment is needed, for example, drying in a 37℃ air-drying oven for 60 min.

[0055] In an embodiment, the distribution density (also referred to as sputtering amount or scribing amount) of the reaction reagent configured on the substrate of the reaction zone is 6-8 μL / cm 2 . For example, the distribution density of the reaction reagent configured on the substrate of the reaction zone is 6 μL / cm 2 , 7 μL / cm 2 , or 8 μL / cm 2 .

[0056] In some embodiments, the substrate of the reaction zone is water-absorbing material. For example, the substrate of the reaction zone is nitrocellulose membrane, PES membrane, PVDF membrane, cellulose acetate membrane, mixed cellulose membrane, NC membrane, water-absorbing paper, or filter paper. The nitrocellulose membrane can have backing or not.

[0057] In some embodiments, in the test paper, the length of the reaction zone is between 5 mm and 15 mm, and the width of the reaction zone is between 3 mm and 5 mm, i.e. the length of the substrate of the reaction zone is between 5 mm and 15 mm, and the width of the substrate of the reaction zone is between 3 mm and 5 mm. For example, the length of the substrate of the reaction zone is 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, or 15 mm, and the width of the substrate of the reaction zone is 3 mm, 4 mm, or 5 mm.

[0058] In some embodiments, the reaction reagent comprises a buffer, a protective agent, a metal ion chelator, a preservative, a surfactant, and urease; wherein the buffer is used to stabilize the pH of the reaction reagent to prevent external factors from affecting the pH of the reaction reagent. The metal ion chelator is used to avoid the metal ions in the reaction reagent from affecting the catalytic reaction. The preservative is used to ensure that the reaction reagent remains stable within the effective period. The surfactant is used to facilitate the uniform distribution of the reaction reagent on the substrate in the reaction area. The urease is used to catalyze the reaction with urea in the body fluid. The protective agent can include at least one of a protein protective agent, a sugar protective agent, and a reducing protective agent. The protein protective agent is used to prevent the denaturation or inactivation of urease. The sugar protective agent is used to stabilize urease during the drying process to prevent urease from being unstable in structure or even crystallizing due to changes in the hydration layer environment. The reducing protective agent is used to prevent oxidation reactions in the reaction reagent, and in particular, the reducing protective agent can provide a reducing environment to slow down the oxidation of the disulfide bond of urease by oxygen in the air, thereby changing the three-dimensional structure of urease. It should be noted that the roles of the substances (buffer, protective agent, metal ion chelator, preservative, surfactant, and urease) in the reaction reagent described in the embodiments of the present application are the main roles of the substances, and the substances can also have other roles that they can play in the reaction reagent.

[0059] In an embodiment, the final concentration of urease in the reaction reagent is 10-50 KU / L. For example, the final concentration of urease in the reaction reagent is 10 KU / L, 15 KU / L, 20 KU / L, 25 KU / L, 30 KU / L, 35 KU / L, 40 KU / L, 45 KU / L, or 50 KU / L. It should be noted that when the concentration of urease in the reaction reagent exceeds the range of 10-50 KU / L, it will affect the accuracy of the detection result (color development of the color development area), and further, it will lead to poor linearity of the standard curve fitted based on the detection result or lead to a non-linear fitted standard curve. For example, when the concentration of urease is greater than 50 KU / L, the linearity of the standard curve is poor. The standard curve is fitted according to different urea concentrations and the G / (R+G+B) values of each image obtained by analysis. For example, the G / (R+G+B) value of the image is obtained according to the G / (R+G+B) value of each pixel point in the image. For example, the G / (R+G+B) value of the image is the average value of the G / (R+G+B) values of all pixel points in the image.

[0060] In an embodiment, the buffer in the reaction reagent is at a final concentration of 0.05-0.5 mM in the reaction reagent. For example, the buffer in the reaction reagent is at a final concentration of 0.05 mM, 0.06 mM, 0.07 mM, 0.08 mM, 0.09 mM, 0.10 mM, 0.11 mM, 0.12 mM, 0.13 mM, 0.14 mM, 0.15 mM, 0.16 mM, 0.17 mM, 0.18 mM, 0.19 mM, 0.20 mM, 0.21 mM, 0.22 mM, 0.23 mM, 0.24 mM, 0.25 mM, 0.26 mM, 0.27 mM, 0.28 mM, 0.29 mM, 0.30 mM, 0.31 mM, 0.32 mM, 0.33 mM, 0.34 mM, 0.35 mM, 0.36 mM, 0.37 mM, 0.38 mM, 0.39 mM, 0.40 mM, 0.41 mM, 0.42 mM, 0.43 mM, 0.44 mM, 0.45 mM, 0.46 mM, 0.47 mM, 0.48 mM, 0.49 mM, or 0.50 mM. In an example, the buffer in the reaction reagent includes potassium phosphate monobasic and sodium phosphate dibasic dihydrate.

[0061] In an embodiment, the final concentration of the sugar protecting agent in the reaction reagent is 2.5-50 mM, e.g., the final concentration of the sugar protecting agent is 2.5 mM, 3.0 mM, 3.5 mM, 4.0 mM, 4.5 mM, 5.0 mM, 5.5 mM, 6.0 mM, 6.5 mM, 7.0 mM, 7.5 mM, 8.0 mM, 8.5 mM, 9.0 mM, 9.5 mM, 10.0 mM, 10.5 mM, 11.0 mM, 11.5 mM, 12.0 mM, 12.5 mM, 13.0 mM, 13.5 mM, 14.0 mM, 14.5 mM, 15.0 mM, 15.5 mM, 16.0 mM, 16.5 mM, 17.0 mM, 17.5 mM, 18.0 mM, 18.5 mM, 19.0 mM, 19.5 mM, 20.0 mM, 20.5 mM, 21.0 mM, 21.5 mM, 22.0 mM, 22.5 mM, 23.0 mM, 23.5 mM, 24.0 mM, 24.5 mM, 25.0 mM, 25.5 mM, 26.0 mM, 26.5 mM, 27.0 mM, 27.5 mM, 28.0 mM, 28.5 mM, 29.0 mM, 29.5 mM, 30.0 mM, 30.5 mM, 31.0 mM, 31.5 mM, 32.0 mM, 32.5 mM, 33.0 mM, 33.5 mM, 34.0 mM, 34.5 mM, 35.0 mM, 35.5 mM, 36.0 mM, 36.5 mM, 37.0 mM, 37.5 mM, 38.0 mM, 38.5 mM, 39.0 mM, 39.5 mM, 40.0 mM, 40.5 mM, 41.0 mM, 41.5 mM, 42.0 mM, 42.5 mM, 43.0 mM, 43.5 mM, 44.0 mM, 44.5 mM, 45.0 mM, 45.5 mM, 46.0 mM, 46.5 mM, 47.0 mM, 47.5 mM, 48.0 mM, 48.5 mM, 49.0 mM, 49.5 mM, or 50.0 mM. In an example, the sugar protecting agent in the reaction reagent comprises sucrose and / or trehalose.

[0062] In an embodiment, the final concentration of the protein protecting agent in the reaction reagent is 1-5 mM, e.g., the final concentration of the protein protecting agent is 1.0 mM, 1.5 mM, 2.0 mM, 2.5 mM, 3.0 mM, 3.5 mM, 4.0 mM, 4.5 mM, or 5.0 mM. In an example, the protein protecting agent in the reaction reagent comprises bovine serum albumin.

[0063] In an embodiment, the final concentration of the reducing protective agent in the reaction reagent is 0.5-5 mM, for example, the final concentration of the protein-based protective agent is 0.5 mM, 0.6 mM, 0.7 mM, 0.8 mM, 0.9 mM, 1.0 mM, 1.1 mM, 1.2 mM, 1.3 mM, 1.4 mM, 1.5 mM, 1.6 mM, 1.7 mM, 1.8 mM, 1.9 mM, 2.0 mM, 2.1 mM, 2.2 mM, 2.3 mM, 2.4 mM, 2.5 mM, 2.6 mM, 2.7 mM, 2.8 mM, 2.9 mM, 3.0 mM, 3.1 mM, 3.2 mM, 3.3 mM, 3.4 mM, 3.5 mM, 3.6 mM, 3.7 mM, 3.8 mM, 3.9 mM, 4.0 mM, 4.1 mM, 4.2 mM, 4.3 mM, 4.4 mM, 4.5 mM, 4.6 mM, 4.7 mM, 4.8 mM, 4.9 mM, or 5.0 mM. In an example, the reducing protective agent in the reaction reagent includes dithiothreitol.

[0064] In an embodiment, the final concentration of the metal ion chelator in the reaction reagent is 1-5 mM, for example, the final concentration of the metal ion chelator is 1.0 mM, 1.5 mM, 2.0 mM, 2.5 mM, 3.0 mM, 3.5 mM, 4.0 mM, 4.5 mM, or 5.0 mM. In an example, the metal ion chelator in the reaction reagent includes ethylenediaminetetraacetic acid.

[0065] In an embodiment, the final concentration of the preservative in the reaction reagent is 5-10 mM, for example, the final concentration of the preservative is 5.0 mM, 5.5 mM, 6.0 mM, 6.5 mM, 7.0 mM, 7.5 mM, 8.0 mM, 8.5 mM, 9.0 mM, 9.5 mM, 10.0 mM. In an example, the preservative in the reaction reagent includes sodium benzoate.

[0066] In an embodiment, the final concentration of the surfactant in the reaction reagent is 0.5-2 mM, for example, 0.5 mM, 0.6 mM, 0.7 mM, 0.8 mM, 0.9 mM, 1.0 mM, 1.1 mM, 1.2 mM, 1.3 mM, 1.4 mM, 1.5 mM, 1.6 mM, 1.7 mM, 1.8 mM, 1.9 mM, or 2.0 mM. In an example, the surfactant in the reaction reagent includes Triton-X-100.

[0067] In an embodiment, the pH of the reaction reagent is maintained between 4.5 and 6.5. For example, the pH of the reaction reagent is maintained at 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, or 6.5. In an embodiment, the pH adjusting agent for adjusting the reaction reagent to be acidic can be hydrochloric acid, in other words, the reaction reagent further comprises hydrochloric acid.

[0068] It should be noted that when the final concentration of the buffer or other substances in the reaction reagent or the pH value exceeds the above range, the accuracy of the detection result will be affected, and the linear of the standard curve fitted will be poor or the curve fitted will be nonlinear. For example, when the final concentration of the buffer exceeds 0.5 mM, the standard curve fitted based on the detection result will be nonlinear. For another example, when the pH value exceeds 6.5 (for example, 7.4), the standard curve fitted will be nonlinear.

[0069] In a specific embodiment, the reaction reagent is prepared by adding potassium dihydrogen phosphate, disodium hydrogen phosphate dihydrate, trehalose, bovine serum albumin, ethylenediaminetetraacetic acid, dithiothreitol, and a preservative into water, dissolving them sufficiently, adding a surfactant, adjusting the pH to be acidic, and then adding urease; wherein the final concentrations of the potassium dihydrogen phosphate, disodium hydrogen phosphate dihydrate, trehalose, bovine serum albumin, ethylenediaminetetraacetic acid, dithiothreitol, preservative, surfactant, and urease in the reaction reagent are 0.05-0.5 mM, 0.05-0.5 mM, 2.5-50 mM, 1-5 μM, 1-5 μM, 0.5-5 mM, 5-10 mM, 0.5-2 μM, and 10-50 KU / L, respectively.

[0070] In another embodiment, the reaction reagent is prepared by adding potassium dihydrogen phosphate, disodium hydrogen phosphate dihydrate, sucrose, trehalose, bovine serum albumin, ethylenediaminetetraacetic acid, and a preservative into water and dissolving thoroughly, then adding a surfactant and adjusting the pH to be acidic, and then adding urease; wherein the final concentrations of potassium dihydrogen phosphate, disodium hydrogen phosphate dihydrate, sucrose, trehalose, bovine serum albumin, ethylenediaminetetraacetic acid, a preservative, a surfactant, and urease in the reaction reagent are 0.05-0.5 mM, 0.05-0.5 mM, 2.5-50 mM, 2.5-50 mM, 1-5 μΜ, 1-5 μΜ, 5-10 mM, 0.5-2 μΜ, and 10-50 KU / L, respectively. In one example, the final concentrations of potassium dihydrogen phosphate, disodium hydrogen phosphate dihydrate, sucrose, trehalose, bovine serum albumin, ethylenediaminetetraacetic acid, a preservative, a surfactant, and urease in the reaction reagent are 0.1 mM, 0.1 mM, 25 mM, 25 mM, 2.5 μΜ, 2.5 μΜ, 7.5 mM, 1 μΜ, and 30 KU / L, respectively.

[0071] In one embodiment, as shown in FIG. 1, the diffusion zone 4 is disposed on the base layer 1, and the diffusion zone 4 is connected to the rear side / proximal end of the reaction zone 3 for lateral chromatography of the reaction product generated by the reaction zone 3 from the distal end toward the proximal end. Specifically, the diffusion zone 4 is disposed on and connected to the rear side / proximal end of the reaction zone 3, and the diffusion zone 4 can absorb the reaction product in the reaction zone 3 and perform lateral chromatography of the reaction product generated by the reaction zone 3 from the distal end toward the proximal end of the diffusion zone 4, for example, the diffusion zone 4 performs lateral chromatography of the reaction product generated by the reaction zone 3 in the direction of lateral chromatography shown by the arrow in FIG. 1.

[0072] In some embodiments, the diffusion zone 4 can be disposed on the base layer 1 by pasting. For example, the base layer 1 is a PVC plate with adhesive on the back, and the diffusion zone 4 is pasted on the back of the base layer 1. In other examples, the diffusion zone 4 can also be fixed on the base layer by clamping, pressing, or other fixing methods.

[0073] In one embodiment, the diffusion zone is formed by disposing the dispersion reagent on the substrate. In this way, the reactants can be uniformly and rapidly diffused in the diffusion zone to the color development zone in the lateral direction, so as to improve the accuracy and reliability of the detection. In one embodiment, the dispersion reagent can be disposed on the substrate of the diffusion zone by scribing or spraying. For example, the dispersion reagent is uniformly scribed on the substrate of the diffusion zone by a scribing and spraying instrument. For another example, the dispersion reagent is uniformly sprayed on the substrate of the diffusion zone by a scribing and spraying instrument. In another embodiment, the diffusion zone is formed by immersing the substrate in a bubble film tank containing the dispersion reagent. Further, after the dispersion reagent is disposed on the substrate of the diffusion zone, a drying process is required, for example, drying in a 37°C air-drying oven for 2 hours.

[0074] In one embodiment, the distribution density (also referred to as the spraying amount or scribing amount) of the dispersion reagent disposed on the substrate of the diffusion zone is 7-9 μL / cm 2 . For example, the distribution density of the dispersion reagent disposed on the substrate of the diffusion zone is 7 μL / cm 2 , 8 μL / cm 2 , or 9 μL / cm 2 .

[0075] In some embodiments, the substrate of the diffusion zone is a water-absorbing material. For example, the substrate of the diffusion zone is a nitrocellulose membrane, a PES membrane, a PVDF membrane, a cellulose acetate membrane, a mixed cellulose membrane, an NC membrane, a water-absorbing paper, or a filter paper. Among them, the nitrocellulose membrane can have a backing or not.

[0076] In some embodiments, in the test paper, the length of the diffusion zone is between 5 mm and 15 mm, and the width of the diffusion zone is between 3 mm and 5 mm, i.e., the length of the substrate of the diffusion zone is between 5 mm and 15 mm, and the width of the substrate of the diffusion zone is between 3 mm and 5 mm. For example, the length of the substrate of the diffusion zone is 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, or 15 mm, and the width of the substrate of the diffusion zone is 3 mm, 4 mm, or 5 mm.

[0077] In some embodiments, the dispersion reagent comprises a dispersant. The dispersant is used to facilitate dispersion and mixing of the reactants during diffusion in the diffusion zone, so that a more uniform color development can be achieved in the color development zone, thereby avoiding uneven pH distribution in the color development zone due to deviation in the reaction process, reducing reading error, and improving the accuracy of detection. It should be noted that the role of the dispersant described in the embodiments of the present application is the main role of the dispersant, and the dispersant can also have other roles that it can play in the dispersion reagent. The final concentration of the dispersant in the dispersion reagent is 0.5%-1.5%, for example, the final concentration of the dispersant in the dispersion reagent is 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%; wherein the dispersant is exemplified by sorbitol.

[0078] Further, in an embodiment, the dispersion reagent further comprises 0.9% sodium chloride. For example, the dispersion reagent comprises 0.9% sodium chloride and 1.0% sorbitol.

[0079] In another embodiment, the dispersion reagent can further comprise an enzyme inhibitor, for example, the dispersion reagent comprises a dispersant and an enzyme inhibitor, thereby preventing the residual urease in the reactants from continuing to catalyze the reaction while accelerating diffusion. The final concentration of the enzyme inhibitor in the dispersion reagent is 0.01-0.05 mM. In a specific embodiment, the dispersion reagent is prepared by adding sorbitol to water to a final concentration of 0.5%-1.5% sorbitol. For example, the final concentration of sorbitol is 1%.

[0080] In an embodiment, as shown in FIG. 1, the color development zone 5 is disposed on the base layer 1 and is isolated from the reaction zone 3 by the diffusion zone 4, the color development zone 5 is used to absorb the reactants from the lateral chromatography of the diffusion zone 4 to perform color development reaction with the color development substance in the color development zone 5, so as to display the detection result of the body fluid urea. Specifically, the color development zone 5 is disposed on the back side / proximal end of the diffusion zone 4, which is isolated from the reaction zone 3 by the diffusion zone 4, and the color development zone 5 performs color development reaction with the reactants by using the color development substance to display the detection result of the body fluid urea; in this way, the color development zone can improve the stability of the detection result, i.e. the stability of the color development, and prolong the reading time window of the detection result by being isolated from the reaction zone.

[0081] In an embodiment, the pH value of the reactant varies with the concentration of the ammonia ion contained in the reactant, and then the color-developing substance can present different colors when the color-developing reaction is performed, and then the detection result is the color-developing area with different colors, in other words, the detection result can be represented by the color of the color-developing area in the test paper; further, the image of the color-developing area is acquired, and the image is color-analyzed to quantitatively calculate the urea concentration / ammonia ion concentration by the image color of the color-developing area. For example, the value of G / (R+G+B) of the image can be determined by the image of the color-developing area, and then the urea concentration / amount can be determined by the value of G / (R+G+B) of the image and the standard curve.

[0082] In some embodiments, the color-developing area 5 can be arranged on the base layer 1 by pasting. For example, the base layer 1 is a PVC plate with back glue, and the color-developing area 5 is pasted on the back glue side of the base layer 1. In other examples, the color-developing area 5 can also be fixed on the base layer by clamping, pressing and the like.

[0083] In some embodiments, the color-developing area 5 can be arranged on the base layer 1 by pasting. For example, the base layer 1 is a PVC plate with back glue, and the color-developing area 5 is pasted on the back glue side of the base layer 1. In other examples, the color-developing area 5 can also be fixed on the base layer by clamping, pressing and the like.

[0084] In an embodiment, the distribution density (which can also be referred to as the spraying amount or the film-drawing amount) of the color-developing reagent arranged on the base material of the color-developing area is 8-10 μL / cm 2 . For example, the distribution density of the color-developing reagent arranged on the base material of the color-developing area is 8 μL / cm 2 , 9 μL / cm 2 , or 10 μL / cm 2 .

[0085] In some embodiments, the base material of the color-developing area is a water-absorbing material. For example, the base material of the color-developing area includes an NC film, a PES film, a PVDF film, a cellulose acetate film, a mixed cellulose film, a water-absorbing paper, or a filter paper.

[0086] In some embodiments, in the test paper, the length of the chromogenic zone is between 5mm-15mm, and the width of the chromogenic zone is between 3mm-5mm, i.e. the length of the substrate of the chromogenic zone is between 5mm-15mm, and the width of the substrate of the chromogenic zone is between 3mm-5mm. For example, the length of the substrate of the chromogenic zone is 4mm, 5mm, 6mm, 7mm, 8mm, 9mm, 10mm, 11mm, 12mm, 13mm, 14mm, or 15mm, and the width of the substrate of the chromogenic zone is 3mm, 4mm, or 5mm.

[0087] In some embodiments, the chromogenic reagent comprises a buffer, a chromogenic substance, a preservative, and a surfactant. The buffer is used to stabilize the pH value of the chromogenic reagent to prevent external factors from affecting the pH value of the chromogenic reagent. The preservative is used to ensure that the chromogenic reagent remains stable within the effective period. The surfactant is used to promote the uniform distribution of the chromogenic reagent on the substrate of the chromogenic zone. The chromogenic substance is used to undergo a chromogenic reaction to obtain the detection result.

[0088] In an embodiment, the final concentration of the buffer in the chromogenic reagent is 0.05-0.5mM. For example, the final concentration of the buffer in the chromogenic reagent is 0.05mM, 0.06mM, 0.07mM, 0.08mM, 0.09mM, 0.10mM, 0.11mM, 0.12mM, 0.13mM, 0.14mM, 0.15mM, 0.16mM, 0.17mM, 0.18mM, 0.19mM, 0.20mM, 0.21mM, 0.22mM, 0.23mM, 0.24mM, 0.25mM, 0.26mM, 0.27mM, 0.28mM, 0.29mM, 0.30mM, 0.31mM, 0.32mM, 0.33mM, 0.34mM, 0.35mM, 0.36mM, 0.37mM, 0.38mM, 0.39mM, 0.40mM, 0.41mM, 0.42mM, 0.43mM, 0.44mM, 0.45mM, 0.46mM, 0.47mM, 0.48mM, 0.49mM, or 0.50mM. In an example, the buffer in the chromogenic reagent comprises citric acid monohydrate and sodium citrate dihydrate.

[0089] In an embodiment, the final concentration of the preservative in the chromogenic reagent is 5-10mM, for example, the final concentration of the preservative in the chromogenic reagent is 5.0mM, 5.5mM, 6.0mM, 6.5mM, 7.0mM, 7.5mM, 8.0mM, 8.5mM, 9.0mM, 9.5mM, or 10.0mM. In an example, the preservative in the chromogenic reagent comprises sodium benzoate.

[0090] In one embodiment, the final concentration of the surfactant in the color developing reagent is 0.5-2 μM, for example, the final concentration of the surfactant in the color developing reagent is 0.5 μM, 0.6 μM, 0.7 μM, 0.8 μM, 0.9 μM, 1.0 μM, 1.1 μM, 1.2 μM, 1.3 μM, 1.4 μM, 1.5 μM, 1.6 μM, 1.7 μM, 1.8 μM, 1.9 μM, or 2.0 μM. In one example, the surfactant in the reaction reagent includes Triton-X-100.

[0091] In one embodiment, the final concentration of the color developing substance in the color developing reagent is 1-5 mM, for example, the final concentration of the color developing substance in the color developing reagent is 1 mM, 1.5 mM, 2.0 mM, 2.5 mM, 3.0 mM, 3.5 mM, 4.0 mM, 4.5 mM, or 5.0 mM. In one example, the color developing substance in the color developing reagent is phenol red. In other examples, the color developing substance can also be other pH indicators suitable for detecting urea.

[0092] In one embodiment, the pH value of the color developing reagent is maintained between 2.5-5.5. For example, the pH value of the color developing reagent is maintained at 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, or 5.5. In one embodiment, the pH adjusting agent for adjusting the color developing reagent to be acidic can be hydrochloric acid, in other words, the color developing reagent also includes hydrochloric acid.

[0093] It should be noted that when the final concentration of the buffer or other substances in the color developing reagent or the pH value exceeds the above range, it will also affect the accuracy of the detection result, and further cause the linear of the fitted standard curve to be poor or the fitted curve to be nonlinear.

[0094] In one specific embodiment, the color developing reagent is prepared by adding citric acid monohydrate, sodium citrate dihydrate, phenol red, and preservative to water and fully dissolving, then adding surfactant, and adjusting the pH to be acidic; wherein the final concentration of citric acid monohydrate, sodium citrate dihydrate, phenol red, preservative, and surfactant in the color developing reagent is 0.05-0.5 mM, 0.05-0.5 mM, 1-5 mM, 5-10 mM, 0.5-2 μM, respectively. In one example, the final concentration of citric acid monohydrate, sodium citrate dihydrate, phenol red, preservative (such as sodium benzoate), and surfactant (such as Triton X 100) in the color developing reagent is 0.1 mM, 0.1 mM, 2.5 mM, 7.5 mM, and 1 μM, respectively.

[0095] The back side of the color development zone is not provided with water-absorbable material. Due to the size limitation of the color development zone, the water holding capacity of the color development zone is limited. After the color development zone is filled with the reactant, the reactant in the reaction zone loses the driving force for continuous lateral migration through capillary action, thereby physically isolating the path for continuous migration of the reactant generated in the reaction zone to the color development zone, and objectively achieving the effect of terminating the color development reaction. Further, the detection result of the color development zone after the reaction is completed is stably displayed, and the color does not continue to change, thereby further prolonging the reading time window.

[0096] In an embodiment, the test paper further comprises a protective layer covering any one or more of the reaction zone, the diffusion zone, and the color development zone. The protective layer is used to control the evaporation of water and the escape of ammonia gas. Specifically, the concentration of ammonium ions in the reactant is a direct factor affecting the color development intensity of the color development zone. The evaporation of water and the escape of ammonium ions in the form of ammonia gas will both cause changes in the concentration of ammonium ions in the reaction solution, thereby affecting the color development intensity of the color development zone. Further, the protective layer can also be used to fix reagents. In some examples, the test paper comprises a protective layer covering any one of the reaction zone, the diffusion zone, and the color development zone. In other examples, the test paper comprises a protective layer covering any two of the reaction zone, the diffusion zone, and the color development zone; for example, as shown in FIG. 1, the test paper comprises a protective layer 6 covering the reaction zone 3 and the color development zone 5. In this way, the problem of evaporation of water and escape of ammonia gas in the reaction zone 3 and the color development zone 5 can be avoided, and the protective layer 6 fixing the reaction reagent can avoid the migration of the reaction reagent to the diffusion zone 4 or even the color development zone 5, thereby affecting the termination of the reaction. The protective layer 6 fixing the color development reagent can ensure that the color development reagent is stably developed in a certain area without migrating with the liquid, thereby ensuring the stability of the sampling of the color development result, and further ensuring the accuracy and stability of the detection. Further, in yet other embodiments, the test paper comprises a protective layer covering the reaction zone, the diffusion zone, and the color development zone. In this way, the problem of evaporation of water and escape of ammonia gas during the entire process of diffusion of the reactant from the reaction zone to the color development zone can be avoided, thereby further improving the accuracy of the detection.

[0097] In embodiments in which the body fluid is saliva, the content of urea in saliva is low. By providing the protective layer in any of the above embodiments in the test paper, the accuracy of saliva urea detection can be improved.

[0098] In one embodiment, the protective layer is formed by disposing a protective reagent on any one or more of the reaction zone, diffusion zone, and color development zone. The formation of the protective layer is described by way of example using a test paper comprising a protective layer covering the reaction zone and color development zone. After the reaction reagent is disposed on the substrate of the reaction zone and the color development reagent is disposed on the substrate of the color development zone, the protective reagent is disposed on the reaction zone and color development zone. It should be noted that the size of the reaction layer and color development layer can be larger than the size defined in the above embodiment, as long as the size of the color development zone and reaction zone of the test paper satisfies the above definition. Further, after the protective reagent is disposed on the reaction zone and color development zone, a drying process is required, for example, drying in a 37°C air-drying oven for 60 minutes.

[0099] In one embodiment, the distribution density (also referred to as the spraying amount or film coating amount) of the protective reagent disposed on the reaction zone, diffusion zone, and / or color development zone is 14-16 μL / cm 2 . For example, the distribution density of the protective reagent disposed on the reaction zone, diffusion zone, and / or color development zone is 14 μL / cm 2 , 15 μL / cm 2 , or 17 μL / cm 2 .

[0100] In one embodiment, the protective reagent comprises a buffer and a film forming agent. The buffer is used to stabilize the pH value of the reaction reagent to prevent the influence of external factors on the pH value of the reaction reagent. The film forming agent is used to form a protective film on the surface of the reaction zone and color development zone.

[0101] In an embodiment, the final concentration of the buffer in the protection reagent is 0.05-0.5 mM. For example, the final concentration of the buffer in the protection reagent is 0.05 mM, 0.06 mM, 0.07 mM, 0.08 mM, 0.09 mM, 0.10 mM, 0.11 mM, 0.12 mM, 0.13 mM, 0.14 mM, 0.15 mM, 0.16 mM, 0.17 mM, 0.18 mM, 0.19 mM, 0.20 mM, 0.21 mM, 0.22 mM, 0.23 mM, 0.24 mM, 0.25 mM, 0.26 mM, 0.27 mM, 0.28 mM, 0.29 mM, 0.30 mM, 0.31 mM, 0.32 mM, 0.33 mM, 0.34 mM, 0.35 mM, 0.36 mM, 0.37 mM, 0.38 mM, 0.39 mM, 0.40 mM, 0.41 mM, 0.42 mM, 0.43 mM, 0.44 mM, 0.45 mM, 0.46 mM, 0.47 mM, 0.48 mM, 0.49 mM, or 0.50 mM. In an example, the buffer in the protection reagent includes potassium dihydrogen phosphate and disodium hydrogen phosphate dihydrate.

[0102] In an embodiment, the final concentration of the film forming agent in the protection reagent is 0.5%-1.5%, for example, the final concentration of the film forming agent in the protection reagent is 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%. In an example, the film forming agent in the protection reagent includes chitosan, chitosan quaternary ammonium salt, carboxymethyl chitosan, starch, modified starch, chondroitin sulfate, keratin, silk protein, cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, konjac glucomannan, dextran, alginate, carrageenan, xanthan gum, gum arabic, poloxamer, polyethylene glycol, polylactic acid, polylysine, polyglycolide, polyvinyl alcohol, polyacrylonitrile, or polyvinylpyrrolidone.

[0103] In an embodiment, the pH value of the protection reagent is maintained between 4.5-6.5. For example, the pH value of the protection reagent is maintained at 4.5, 4.6, 4.7, 4.8, 4.9, 5.0, 5.1, 5.2, 5.3, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, or 6.5. In an embodiment, the pH adjusting agent for adjusting the protection reagent to be acidic can be hydrochloric acid, in other words, the protection reagent further includes hydrochloric acid.

[0104] In one embodiment, the protective reagent is prepared by adding potassium dihydrogen phosphate and disodium hydrogen phosphate dihydrate into water, dissolving thoroughly, adjusting pH to be acidic, and then adding a film forming agent; wherein the final concentrations of potassium dihydrogen phosphate, disodium hydrogen phosphate dihydrate, and the film forming agent in the protective reagent are 0.05-0.5 mM, 0.05-0.5 mM, and 0.5%-1.5%, respectively. In one example, the final concentrations of potassium dihydrogen phosphate, disodium hydrogen phosphate dihydrate, and the film forming agent in the protective reagent are 0.07 mM, 0.03 mM, and 1%, respectively.

[0105] It should be noted that when the final concentration of the buffer or other substances in the protective reagent or the pH value exceeds the above range, it will also affect the accuracy of the detection result, and thus will lead to poor linearity of the fitted standard curve or non-linear curve.

[0106] Referring to FIG. 1, the test paper for detecting urea in body fluid further comprises a cover plate 7 arranged at the proximal end of the color developing zone 5. For example, the cover plate 7 is directly pasted on the base layer 1. For another example, the cover plate 7 is fixed at the proximal end of the color developing zone 5 by clamping, pressing, or other fixing methods. In this embodiment, the cover plate 7 is made of non-water-absorbing material. Non-water-absorbing material refers to material with a water absorption rate lower than the preset water absorption rate. For example, the cover plate 7 is made of PVC material. By arranging the cover plate 7 to be made of non-water-absorbing material, the color developing zone 5 can be prevented from absorbing too much reactant, so as to improve the stability of color development and the accuracy of detection.

[0107] Further, as shown in FIG. 1, the distal end of the cover plate 7 and the proximal end of the color developing zone 5 further have an overlapping area. The length of the overlapping area is, for example, 1-2 mm.

[0108] In some embodiments, in the test paper, the length of the cover plate is between 15 mm and 30 mm, and the width of the cover plate is between 3 mm and 5 mm. For example, the length of the cover plate is 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, or 30 mm, and the width of the cover plate is 3 mm, 4 mm, or 5 mm.

[0109] The reaction zone, the diffusion zone, and the color developing zone in the test paper for detecting urea in body fluid described in the present application can be formed on different substrates and connected in sequence as shown in FIG. 1, or can be formed on different regions of the same substrate, or can be adjacent reaction zone and diffusion zone, or adjacent diffusion zone and color developing zone formed on different regions of the same substrate.

[0110] In one embodiment, as shown in FIG. 1, the diffusion zone 4, the reaction zone 3, and the color development zone 5 are formed on different substrates, and the diffusion zone 4 is located between the reaction zone 3 and the color development zone 5 to spatially separate the reaction zone 3 and the color development zone 5; in other words, the substrates of the diffusion zone 4, the reaction zone 3, and the color development zone 5 are three independent substrates, and the diffusion zone 4 is arranged between the reaction zone 3 and the color development zone 5 to spatially separate the reaction zone 3 and the color development zone 5. In this embodiment, the sampling zone 2, the reaction zone 3, the diffusion zone 4, and the color development zone 5 can be adhered to the base layer 1 by an adhesive on the base layer 1. The adhesive is exemplified by a back adhesive on the base layer 1.

[0111] Further, as shown in FIG. 1, the sampling zone 2, the reaction zone 3, the diffusion zone 4, and the color development zone 5 are sequentially and overlappingly arranged on the base layer 1 to form a liquid passage through the overlapping regions, so that the test paper can perform lateral chromatography on the reactants. In one example, the length of the overlapping region is 1-2 mm. For example, the length of the overlapping region is 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, or 3.0 mm.

[0112] In another embodiment, as shown in FIG. 2, a cross-sectional view of a test paper for detecting urea in a body fluid according to another embodiment of the present application is shown. As shown, the reaction zone 3, the diffusion zone 4, and the color development zone 5 are sequentially formed on different regions of the same substrate. Specifically, the reaction zone 3 is formed on a distal region of a substrate, the color development zone 5 is formed on a proximal region of the substrate, and the diffusion zone 4 is formed on an intermediate region of the substrate. For example, the distal region, the intermediate region, and the proximal region on a substrate are respectively provided with a reaction reagent, a dispersion reagent, and a color development reagent to form the reaction zone 3, the diffusion zone 4, and the color development zone 5. The distal region, the intermediate region, and the proximal region are sequentially connected. In this embodiment, the whole of the reaction zone 3, the diffusion zone 4, and the color development zone 5 and the sampling zone 2 can be adhered to the base layer 1 by an adhesive on the base layer 1. Further, in one embodiment, the proximal end of the sampling zone 2 and the distal end of the reaction zone 3 have an overlapping region. The length of the overlapping region is exemplified by 1-2 mm.

[0113] In yet another embodiment, the reaction zone and the diffusion zone are formed on different regions of the same substrate, and the color development zone is formed on another independent substrate; further, the proximal end of the sampling zone has an overlapping region with the distal end of the reaction zone, and the proximal end of the diffusion zone has an overlapping region with the distal end of the color development zone.

[0114] In yet another embodiment, the reaction zone and the diffusion zone are formed on different regions of the same substrate, and the color development zone is formed on another independent substrate; further, the proximal end of the sampling zone has an overlapping region with the distal end of the reaction zone, and the proximal end of the diffusion zone has an overlapping region with the distal end of the color development zone.

[0115] Based on the above description of the embodiments, in some embodiments, the present application provides a preparation method of the test paper of Embodiment 1 and Embodiment 2 to make two different structures of the test paper for detecting urea in body fluid.

[0116] Embodiment 1:

[0117] In the first step, 1.36 mg of potassium dihydrogen phosphate, 1.78 mg of disodium hydrogen phosphate dihydrate, 8.56 g of trehalose, 250 mg of bovine serum albumin, 10 mg of ethylenediaminetetraacetic acid, 15.43 mg of dithiothreitol, and 100 mg of sodium benzoate are dissolved in ultrapure water, and after being fully dissolved, 150 μL of Triton X 100 is added, hydrochloric acid is added to adjust the pH value of the solution to 6.5, and the solution is diluted to 100 mL. Urease is dissolved in the above solution to ensure that the final concentration of urease is 15 kU / L, and the reaction reagent is prepared. 1 g of sorbitol is dissolved in ultrapure water, and after being fully dissolved, the solution is diluted to 100 mL to prepare the dispersion reagent. 1.68 mg of citric acid monohydrate, 0.59 mg of sodium citrate dihydrate, 0.1 g of phenol red, and 100 mg of sodium benzoate are dissolved in ultrapure water, and after being fully dissolved, 150 μL of Triton X 100 is added, hydrochloric acid is added to adjust the pH value of the solution to 3.5, and the solution is diluted to 100 mL to prepare the color development reagent. 0.95 mg of potassium dihydrogen phosphate, 0.53 mg of disodium hydrogen phosphate dihydrate, and 1 g of chitosan are dissolved in ultrapure water, and after being fully dissolved, the pH value of the solution is adjusted to 6.5 by adding hydrochloric acid, and the solution is diluted to 100 mL to prepare the protection reagent.

[0118] The second step, the prepared reaction reagent is uniformly sprayed on the substrate (nitrocellulose membrane) of the reaction area by the membrane scribing gold spraying instrument at a spraying amount of 7 μL / cm2, and is placed in a 37°C air drying oven for drying for 60 min; the substrate (nitrocellulose membrane) of the diffusion area is placed in a bubble film tank containing 60 mL of the dispersion reagent for soaking for 5 min and then taken out, and is placed in a 37°C air drying oven for drying for 2 h; the prepared color developing reagent is uniformly sprayed on the substrate (nitrocellulose membrane) of the color developing area by the membrane scribing gold spraying instrument at a spraying amount of 9 μL / cm2, and is placed in a 37°C air drying oven for drying for 60 min; then, after the nitrocellulose membrane sprayed with the reaction reagent and the color developing reagent is dried, the prepared protection reagent is uniformly sprayed on the reaction area and the color developing area respectively by the membrane scribing gold spraying instrument at a spraying amount of 15 μL / cm2, and is placed in a 37°C air drying oven for drying for 60 min.

[0119] The third step, an 18 mm long sampling area (glass fiber membrane), a 7 mm long reaction area, an 8 mm long diffusion area, a 7 mm long color developing area and a 15 mm long cover plate are overlapped and pasted on the PVC plate in sequence, and after pasting, a 4 mm wide test paper for detecting body fluid urea is cut, and the structure of the test paper prepared in this embodiment is shown in FIG. 1.

[0120] Example 2

[0121] The first step, 1.36 mg of potassium dihydrogen phosphate, 1.78 mg of disodium hydrogen phosphate dihydrate, 8.56 g of trehalose, 250 mg of bovine serum albumin, 10 mg of ethylenediaminetetraacetic acid, 15.43 mg of dithiothreitol, 100 mg of sodium benzoate are dissolved in ultrapure water, after fully dissolved, 150 μL of Triton X 100 is added, hydrochloric acid is added to adjust the pH value of the solution to 6.5 and constant volume to 100 mL, urease is dissolved in the above solution, and the final concentration of urease is 15 kU / L, and the reaction reagent is prepared; 1 g of sorbitol is dissolved in ultrapure water, after fully dissolved, constant volume to 100 mL, and the dispersion reagent is prepared; 1.68 mg of citric acid monohydrate, 0.59 mg of sodium citrate dihydrate, 0.1 g of phenol red, 100 mg of sodium benzoate are dissolved in ultrapure water, after fully dissolved, 150 μL of Triton X 100 is added, hydrochloric acid is added to adjust the pH value of the solution to 3.5 and constant volume to 100 mL, and the color developing reagent is prepared; 0.95 mg of potassium dihydrogen phosphate, 0.53 mg of disodium hydrogen phosphate dihydrate, 1 g of chitosan are dissolved in ultrapure water, after fully dissolved, hydrochloric acid is added to adjust the pH value of the solution to 6.5 and constant volume to 100 mL, and the protection reagent is prepared.

[0122] The second step, taking a NC membrane as the substrate of the reaction zone, diffusion zone and color developing zone, using a membrane scribing and gold spraying instrument to draw lines of the prepared reaction reagent, dispersion reagent and color developing reagent in the corresponding areas with a membrane scribing amount of 7 μL / cm, 8 μL / cm and 9 μL / cm respectively. The scribed area of the reaction reagent is the first 7 mm, the scribed area of the dispersion reagent is 8 mm long and connected with the scribed area of the reaction reagent, and the scribed area of the color developing reagent is 7 mm long and connected with the scribed area of the dispersion reagent. After each scribing is completed, dry in a 37°C air-drying oven for 60 min; after drying, use a membrane scribing and gold spraying instrument to uniformly spray the prepared protective reagent on the reaction zone and the color developing zone with a spraying amount of 15 μL / cm2, and dry in a 37°C air-drying oven for 60 min.

[0123] The third step, overlapping and pasting a 15 mm long sampling area (glass fiber membrane), a 22 mm long NC membrane and a 15 mm long cover plate on a PVC plate in turn, and cutting into 4 mm wide test paper for detecting body fluid urea after pasting. The structure of the test paper prepared in this embodiment is shown in FIG. 2.

[0124] The test paper for detecting body fluid urea corresponding to the preparation method of Example 1 was tested. Six portions of saliva with urea concentrations of 2 mM, 4 mM, 6 mM, 8 mM, 10 mM and 12 mM were taken as samples, and the amount of each portion of saliva was 100 μL. 100 μL of each of the six portions of saliva was dropped on the sampling area of the six test papers respectively, and the reaction was carried out at room temperature. The color development of the color developing zone remained stable within the time window of 5-10 min after the sample was added, and the color developing zone of the saliva of the six test papers was photographed at 5 min. After analyzing the images, a standard curve was fitted according to the different urea concentrations and the G / (R+G+B) values of the images obtained by analysis. The standard curve obtained by fitting is shown in FIG. 3. According to FIG. 3, the standard deviation of the fitted standard curve is 0.9925, which has good linearity. In other words, the test paper in this embodiment has high detection accuracy.

[0125] Further, five test papers with urea concentrations of 2 mM, 4 mM, 6 mM, 8 mM and 10 mM were taken from the above examples, and the color developing zone of the saliva of the five test papers was photographed and analyzed at 5 min, 8 min and 10 min respectively. The G / (R+G+B) values of the images of different urea concentrations at different times are shown in the following table:

[0126] According to the table, the values of G / (R+G+B) corresponding to each urea concentration remain relatively stable at 5 min, 8 min, and 10 min. According to the table and FIG. 3, the test paper of the present application has both high detection accuracy and a long reading time window, thereby meeting the sampling time requirements of users for self-testing.

[0127] It should be noted that the stable color development time of 5-10 min shown in the table should not be understood as a limitation on the stable color development time of the test paper of the present application. In the laboratory, the test paper for detecting salivary liquid urea corresponding to the preparation method of Example 1 was tested, and a stable color development time of 5-15 min was achieved. Further, the test paper can achieve a stable color development time of up to 5-30 min through optimized design. For example, by optimizing the concentrations of each substance in the reagent and the sizes of each region in the test paper within the optional ranges of the concentrations of each substance and the optional ranges of the sizes of each region provided in the embodiments of the present application, the test paper of the present application can achieve a stable color development time of 5-30 min.

[0128] In a comparative example, six test papers were prepared by replacing the urease concentration in the preparation method of Example 1 with 65 kU / L. Six portions of saliva with urea concentrations of 2 mM, 4 mM, 6 mM, 8 mM, 10 mM, and 12 mM were taken as samples, each portion of saliva having a volume of 100 μL. The six portions of 100 μL saliva were dropped onto the sampling regions of the six test papers, respectively, and reacted at room temperature. The color development regions of the saliva of the six test papers were photographed at 5 min. After analyzing the images, a standard curve was fitted according to different urea concentrations and the analyzed images G / (R+G+B). The fitted images are shown in FIG. 4. FIG. 4 shows the standard curve diagram corresponding to the test paper prepared by the reaction reagent with a urease concentration of 65 kU / L in the comparative example. As shown in FIG. 4, when the urease concentration exceeds the limited range of the urease concentration in the foregoing example, the linearity of the standard curve is poor.

[0129] In another comparative example, six test papers were prepared by replacing the buffer concentration of the reaction reagent in the preparation method of Example 1 with 1.25 and the pH of the reaction reagent was 7.4, and six samples of saliva with urea concentrations of 2 mM, 4 mM, 6 mM, 8 mM, 10 mM, and 12 mM were taken, each sample of saliva was 100 μL, and 100 μL of each sample of saliva was dropped on the sampling area of the six test papers, and the reaction was carried out at room temperature. The color development area of the saliva of the six test papers was photographed at 5 min. After analyzing the images, a standard curve was fitted according to the different urea concentrations and the G / (R+G+B) of the images obtained by analysis, and the fitted images are shown in FIG. 5. FIG. 5 shows the standard curve diagram corresponding to the test paper prepared by using the reaction reagent with a buffer concentration of 1.25 mM and a pH of 7.4 in the comparative example. As shown in FIG. 5, when the buffer concentration and the pH value exceed the limited range of the buffer concentration and the pH value in the foregoing examples, the standard curve is nonlinear.

[0130] It should be noted that the urea concentration of the samples in FIG. 3 and the table should not be understood as a limitation of the detectable urea concentration range of the present application. For example, by selecting within the final concentration range of the urease and the color developing substance provided in the foregoing examples of the present application, the test paper can have good detection accuracy in the detection range of different urea concentrations. For example, refer to FIG. 7, which shows the standard curve diagram of the test paper for detecting urea in the range of 5-30 mM in another example of the present application. As shown in the figure, the standard deviation of the fitted standard curve is 0.9923, also with good linearity.

[0131] In an example, refer to FIG. 6 in combination with FIGS. 1 and 2, which shows a top view of the kit for detecting urea in body fluid in an example of the present application. As shown in the figure, the kit for detecting urea in body fluid includes a shell 8, a base layer 1, a sampling area 2, a reaction area 3, a diffusion area 4, and a color development area 5. The shell 8 is provided with a first window 81 at the distal end of the shell 8 and a second window 82 away from the first window 81; the sampling area 2, the reaction area 3, the diffusion area 4, and the color development area 5 are arranged on the base layer 1, which is arranged in the built-in space of the shell 8. The sampling area 2 absorbs the body fluid to be detected through the first window 81, the diffusion area 4 is arranged on the base layer 1 and is connected to the proximal end of the reaction area 3 for lateral transmission of the reactants of the reaction area; the color development area 5 corresponds to the second window 82 and is isolated from the reaction area 3 through the diffusion area 4. The color development area 5 is used to absorb the reactants laterally transmitted by the diffusion area 4 to perform color development reaction by using the color developing substance in the color development area 5, so as to display the detection result of urea in body fluid through the second window 82.

[0132] In an embodiment, the housing is detachable so as to facilitate fixing the test paper / base layer in the housing after the housing is detached. For example, the housing comprises an upper housing and a lower housing which are detachable. In an example, the lower housing has a fixing groove in which the test paper / base layer is fixed. In another example, the test paper / base layer is fixed to the lower housing by means of a sticking structure. It is to be noted that the present application does not limit the arrangement of the test paper / base layer.

[0133] As shown in FIG. 6, the first window is in the shape of an ellipse and the second window is in the shape of a rectangle. It is to be noted that the present application does not limit the shape of the first window and the second window, and in other embodiments, the first window and the second window can also be in the shape of a rectangle, a circle or other regular or irregular shapes.

[0134] In some embodiments, the size of the area corresponding to the first window needs to be slightly smaller than or equal to the size of the sampling area so as to ensure sufficient contact between the body fluid and the sampling area and control the amount of body fluid entering. In an embodiment, the size of the second window needs to be slightly smaller than or equal to the size of the color development area so as to ensure that the color change in the color development area can be clearly visible through the second window.

[0135] In an embodiment, the first window and the second window are provided in the upper housing of the housing, the first window is located at the distal end of the upper housing, and the second window is away from the first window.

[0136] The base layer is located in the housing. The sampling area is arranged at the distal end of the base layer and is used to absorb the body fluid to be detected through the first window. The reaction area is arranged on the base layer and is used to absorb the body fluid in the sampling area to react with urease in the reaction area. The diffusion area is arranged on the base layer and is in contact with the proximal end of the reaction area and is used to laterally transfer the reactants of the reaction area. The color development area corresponding to the second window is arranged on the base layer and is isolated from the reaction area through the diffusion area, and the color development area is used to absorb the reactants laterally transferred from the diffusion area to perform color development reaction with color development substances in the color development area so as to display the detection result of the body fluid urea through the second window.

[0137] Further, in an embodiment, the kit for detecting body fluid urea further comprises a protective layer covering the reaction area and the color development area.

[0138] Further, in an embodiment, the kit for detecting body fluid urea further comprises a cover plate arranged at the proximal end of the color development area.

[0139] In the present application, the configuration and function of each layer (base layer, sampling area, reaction area, diffusion area, color development area, and protective layer) and cover plate in the kit for detecting urea in body fluid are the same as or similar to those of the corresponding layers (base layer, sampling area, reaction area, diffusion area, color development area, and protective layer) and cover plate in the test paper for detecting urea in body fluid, and will not be repeated here.

[0140] In summary, the test paper and kit for detecting urea in body fluid provided by the present application can effectively separate the transversely arranged reaction area and color development area by the intermediate diffusion area, which can prevent urease in the reaction area from entering the color development area, and further play a role in terminating the catalytic reaction of urease to improve the stability of the color development reaction in the color development area, thereby prolonging the reading time window of the color development result in the color development area for the convenience of individual users. In addition, the test paper of the present application uses saliva as the liquid to be detected, which can further facilitate individual use. Moreover, the present application can further prolong the reading time window and the stability of color development and improve the detection accuracy by providing a protective layer. Furthermore, the present application can further improve the stability of color development and prolong the reading time window by setting the rear side of the color development area as a cover plate of non-absorbent material.

[0141] In some embodiments, the present application provides a method for detecting urea in body fluid, which can be executed by a computer device configured with a system for detecting urea in body fluid. For example, the system for detecting urea in body fluid can be configured as a module in the computer device for execution. The system for detecting urea in body fluid is a software tool or software module that can process data by means of hardware devices in the computer device and the operating environment provided by the operating system.

[0142] In an embodiment, the computer device can be configured as an electronic device, i.e., the method for detecting urea in body fluid is executed by an electronic device, for example, the electronic device includes desktop computers, notebook computers, tablet computers, smart televisions, smart phones, and tablet computers, and the electronic device can also be an electronic device composed of a host with multiple virtual machines and a human-computer interaction device (such as a touch display screen, a keyboard, and a mouse) corresponding to each virtual machine.

[0143] In an embodiment, the computer device can be configured as a server, i.e., the server executes the method for detecting urea in body fluid. The server can be arranged on one or more physical servers according to functions, loads, and various factors. In some examples, the server can be a cloud architecture-based server, which refers to a cloud computing platform provided by a cloud computing provider, and the cloud computing platform can provide IaaS (Infrastructure as a Service), PaaS (Platform as a Service), SaaS (Software as a Service), and other services. Among them, the cloud computing platform includes Public Cloud, Private Cloud, Hybrid Cloud, and the like. In some examples, the server can be composed of a distributed or centralized server cluster. For example, the server cluster is composed of at least one physical server. Each physical server is configured with multiple virtual servers, and each virtual server runs at least one functional module in the system, and the virtual servers communicate with each other through a network.

[0144] In an embodiment, referring to FIG. 8, a flowchart of the method for detecting urea in body fluid in an embodiment of the present application is shown. As shown in the figure, the method for detecting urea in body fluid includes steps S110, S120, and S130. The following describes each embodiment with the method for detecting urea in body fluid executed by a computer device as an example.

[0145] In step S110, the computer device acquires a detection image obtained by photographing a test paper or a test kit by using an image capturing device.

[0146] The detection image is photographed within a reading time window after the test paper or test kit absorbs the body fluid to be detected. Specifically, after the sampling area of the test paper or test kit in any of the foregoing embodiments absorbs the body fluid to be detected, the reaction area reacts and the reactant is laterally chromatographed to the color developing area through the diffusion area. After the reactant reacts with the color developing substance in the color developing area, the color developing reaction is stable within the reading time window (i.e., the stable display time described above), and the user can photograph the test paper or test kit by using the image capturing device (such as the camera configured on the smart phone) configured on the computer device or the image capturing device independent of the computer device to acquire the detection image within the reading time window. In the following embodiments, the user photographs by using the image capturing device configured on the computer device to acquire the detection image is taken as an example for description.

[0147] The detection image includes an image of a color development region in a test paper or a test kit. Specifically, the detection image includes a color image of the color development region. The image taking device is an image taking device that can acquire a color image. For example, the image taking device is a camera including a CCD or a CMOS.

[0148] After the computer device acquires the detection image, the computer device performs step S120.

[0149] In step S120, the computer device determines color development data corresponding to the image of the color development region based on the detection image.

[0150] Specifically, the computer device determines the image of the color development region by performing image recognition on the detection image, and then obtains the color development data based on R, G, and B values of each pixel point in the image of the color development region.

[0151] The color development data is used to represent a color condition of the image of the color development region. In an example, the color development data is a value of G / (R+G+B) of the image of the color development region, and the value of G / (R+G+B) of the image of the color development region is a mean value. For example, a mean value of R, G, and B values of all pixel points in the image of the color development region can be calculated first, and then a value of G / (R+G+B) of the image can be calculated according to the formula G / (R+G+B). For another example, a value of G / (R+G+B) of each pixel point can be calculated first, and then a mean value of G / (R+G+B) of the image of the color development region can be obtained. It should be noted that, according to different software designs or different color development substances in the test paper or the test kit, in other examples, the color development data can also be a value of R / (R+G+B) or a value of B / (R+G+B) of the image of the color development region.

[0152] In step S130, the computer device determines the urea concentration of the body fluid according to the color development data and a standard curve corresponding to the test paper or the test kit.

[0153] In an embodiment, the standard curve represents a corresponding relationship between the urea concentration of the body fluid and the color development data, and thus the urea concentration of the corresponding body fluid can be determined after the standard curve of the test paper or the test kit and the color development data are known. For example, the corresponding urea concentration can be obtained based on the standard curve shown in FIG. 3 and the calculated value of G / (R+G+B) of the image of the color development region. In an example, the standard curve is pre-stored, for example, pre-stored in the computer device or pre-stored in a server in communication connection with the computer device.

[0154] In some embodiments, the standard curves of different batches are different, and therefore the method for detecting urea in body fluid further comprises a step of acquiring batch information of the test paper or kit to determine a standard curve corresponding to the batch information. In an example, a user inputs the batch information of the test paper or kit through an input device (such as a touch screen or keyboard, etc.) of a computer device. In another example, a mark of the batch information is configured on the test paper or kit, for example, the mark is configured on a base layer of the test paper or a shell of the kit by pasting or printing, and accordingly, the detection image further comprises an image of the mark, and then the computer device can acquire the batch information of the test paper or kit by recognizing the image of the mark.

[0155] In an embodiment, the method for detecting urea in body fluid further comprises a step of determining evaluation information of a user according to the determined urea concentration of the body fluid and the type of the body fluid. The evaluation information comprises health information of the user and suggestion information. The health information is exemplified by health condition of the user, and / or treatment effect, etc. The suggestion information is exemplified by diet suggestion, work and rest suggestion, and / or treatment suggestion, etc. In an example, the evaluation information corresponding to different body fluid types and different urea concentrations is pre-stored, and then the computer device can determine the corresponding evaluation information according to the urea concentration of the body fluid and the type of the body fluid. It should be noted that the evaluation information can also be remotely input by a doctor based on different body fluid types and different urea concentrations, and then the computer device can directly acquire the evaluation information to display to the user.

[0156] In an embodiment, referring to FIG. 9, a structural block diagram of a system for detecting urea in body fluid in an embodiment of the present application is shown, the system 9 for detecting urea in body fluid comprises an acquisition module 90, a chromogenic data determination module 91, and a concentration determination module 92.

[0157] The above modules can be implemented in software run by different types of processors. For example, a module of executable code can include one or more physical blocks or logical blocks of computer instructions that are organized as objects, procedures, or functions. However, the executable files of the modules do not have to be physically located together, but can include different commands stored in different locations that, when linked together logically, include the modules and achieve the specified objectives of the modules.

[0158] Of course, a module of executable code can be a single instruction, or many instructions, and can even be distributed over several different code segments, among different programs, and across several memory devices. Similarly, operational data can be identified and illustrated herein within modules, and can be embodied in any suitable form and organized within any suitable type of data structure. The operational data can be collected as a single data set, or can be distributed over different locations including over different storage devices, and can exist, at least partially, merely as electronic signals on a system or network. Where a module or portions of a module are implemented in software, the software portions are stored in one or more computer-readable media memories.

[0159] The acquisition module 90 is configured to acquire a detection image of the test paper or the kit according to any one of the above embodiments, which is obtained by using an image capturing device to capture the test paper or the kit; wherein the detection image is captured within a reading time window after the test paper or the kit absorbs the body fluid to be detected, and the detection image includes an image of the color development zone.

[0160] The color development data determination module 91 is configured to determine color development data corresponding to the image of the color development zone based on the detection image.

[0161] The concentration determination module 92 is configured to determine color development data corresponding to the image of the color development zone based on the detection image.

[0162] In an embodiment, the system for detecting urea in a body fluid further includes a standard curve determination module (not shown), which is configured to acquire batch information of the test paper or the kit to determine a standard curve corresponding to the batch information.

[0163] In an embodiment, the system for detecting urea in a body fluid further includes an evaluation information module (not shown), which is configured to determine evaluation information of a user according to the determined urea concentration of the body fluid and the type of the body fluid.

[0164] Herein, the working modes of the modules in the system 9 for detecting urea in a body fluid according to the present application are the same as or similar to the corresponding steps in the method for detecting urea in a body fluid described above, and will not be described herein again.

[0165] The present application further provides a computer-readable and writable storage medium, which stores at least one program, and the at least one program, when invoked, executes the method for detecting urea in a body fluid described in any one of the above embodiments.

[0166] The application also provides a computer program product in an embodiment, when the computer program product is run on a computer, causes the computer to execute the above related steps to realize the method for detecting body fluid urea described in any of the embodiments.

[0167] The functions described above, if implemented in the form of software function units and sold or used as independent products, can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the application essentially or the parts of the prior art that make contributions or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in the embodiments of the application.

[0168] In the embodiments provided in the application, the computer readable storage medium can include a read-only memory (ROM, Read Only Memory), a random access memory (RAM, Random Access Memory), an EEPROM, a CD-ROM or other optical disk storage device, a magnetic disk storage device or other magnetic storage device, a flash memory, a U disk, a mobile hard disk, or any other medium capable of storing desired program code in the form of instructions or data structures and capable of being accessed by a computer. In addition, any connection can be appropriately referred to as a computer readable medium. For example, if the instructions are sent from a website, a server or other remote source using a coaxial cable, an optical fiber cable, a twisted pair, a digital subscriber line (DSL) or wireless technologies such as infrared, radio and microwave, the coaxial cable, the optical fiber cable, the twisted pair, the DSL or the wireless technologies such as infrared, radio and microwave are included in the definition of the medium. However, it should be understood that the computer readable storage medium and the data storage medium do not include connections, carriers, signals or other temporary media, but are intended to be directed to non-transitory, tangible storage media. As used in the application, magnetic disks and optical disks include compact disks (CD), laser disks, optical disks, digital versatile disks (DVD), floppy disks and Blu-ray disks, in which magnetic disks usually magnetically copy data, and optical disks optically copy data with a laser.

[0169] The application also discloses a computer device for realizing the method for detecting body fluid urea described in any of the embodiments. The computer device is a device capable of digital calculation, logical processing and information processing of data. The computer device includes a storage device and a processing device connected to the storage device.

[0170] In some embodiments, the storage device is configured to store at least one program executable by the processing device to coordinate the method for detecting the body fluid urea described in any of the embodiments above.

[0171] In some embodiments, the storage device includes, but is not limited to, read-only memory, random access memory, non-volatile memory. For example, the storage device includes a flash memory device or other non-volatile solid-state storage device. In some embodiments, the storage device can also include memory that is remote from the one or more processing devices, such as network attached storage accessed via RF circuitry or an external port and a communication network, which can be the Internet, one or more intranets, local area networks, wide area networks, storage area networks, etc., or suitable combinations thereof. A memory controller can control access to the memory by other components of the device, such as the CPU and peripheral interfaces.

[0172] In some embodiments, the processing device includes one or more processors. The processing device is operatively connected with the storage device to perform data read and write operations. The processing device includes one or more general purpose microprocessors, one or more application specific processors (ASICs), one or more digital signal processors, one or more field programmable logic arrays (FPGAs), or any combination thereof.

[0173] Further, the computer device also includes an interface device. In some embodiments, the interface device includes at least one interface unit, each interface unit being configured to output a visual interface, receive a human-machine interaction event generated according to a user's operation (e.g., receive batch information input by a user), etc. For example, the interface device includes, but is not limited to, a serial interface such as an HDMI interface or a USB interface, a parallel interface, etc. In an embodiment, the interface device also includes a network communication unit, which is a device configured to transmit data using a wired or wireless network, examples of which include, but are not limited to, an integrated circuit including a network card, a local area network module such as a WiFi module or a Bluetooth module, a wide area network module such as a mobile network module, etc.

[0174] In an embodiment, the computer device also includes an input device, which is, for example, a touch screen connected to the processing device. The input device is configured to provide a human-machine interaction interface for a user to input. In an embodiment, the computer device also includes an image capturing device connected to the processing device, the image capturing device being configured to capture an image of a test paper or a test kit to obtain a detection image.

[0175] In one or more exemplary aspects, the functions described with the method for detecting urea in body fluid described in the present application can be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, the functions can be stored or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media include both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage medium can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Also, functional

[0176] The flow diagrams and block diagrams in above-described figures of the present application illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present application. In this regard, each block in the flow diagrams or block diagrams can represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical functions. It should also be noted that in some alternative implementations, the functions noted in the blocks can occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently or the blocks can sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and / or flow diagrams, and combinations thereof, can be implemented by special purpose hardware-based systems that perform the specified functions or operations, or combinations of special purpose hardware and computer instructions.

[0177] In summary, the method and system for detecting urea in body fluid, computer device, computer readable storage medium, and computer program product provided by the present application can obtain detection images within a longer reading time window of test paper or test kit, determine the color development data corresponding to the image of the color development zone based on the detection images, and accurately determine the urea concentration of the body fluid by using the pre-configured standard curve.

[0178] The above-described embodiments are merely illustrative of the principles of the present application and the effect thereof, and are not intended to limit the present application. Any person skilled in the art can modify or change the above-described embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical idea of the present application should be covered by the claims of the present application.

Claims

1. A test paper for detecting urea in a body fluid, characterized by, The application relates to a test strip for detecting urea in a body fluid, comprising: a base layer, including a proximal end and a distal end extending laterally from the proximal end; a sampling area arranged at the distal end of the base layer for absorbing the body fluid to be detected; a reaction area arranged at the base layer for absorbing the body fluid in the sampling area to react with urease in the reaction area; a diffusion area arranged at the base layer and connected with the reaction area for laterally chromatographing the reaction product generated by the reaction area from the distal end to the proximal end; a color developing area arranged at the base layer and separated from the reaction area through the diffusion area, for absorbing the reaction product laterally chromatographed by the diffusion area to develop color with color developing substances in the color developing area, so as to display the detection result of urea in the body fluid.

2. The test paper according to claim 1, characterized in that, The base layer is a PVC plate.

3. The test paper according to claim 1, characterized by The material of the sampling area comprises glass fiber membrane, polyester fiber membrane, water absorption paper or filter paper.

4. The test paper according to claim 1, characterized by The base material of the reaction area and the diffusion area comprises nitrocellulose membrane, PES membrane, PVDF membrane, cellulose acetate membrane, mixed cellulose membrane, water absorption paper or filter paper.

5. The test paper according to claim 1, characterized by The reaction area is formed by arranging pre-prepared reaction reagents on the base material.

6. The test paper according to claim 5, characterized in that The reaction reagents comprise buffer, protective agent, metal ion chelating agent, preservative, surfactant and urease; wherein the final concentration of urease in the reaction reagents is 10-50 KU / L.

7. The test paper according to claim 6, characterized in that The reaction reagents are prepared by adding potassium dihydrogen phosphate, disodium hydrogen phosphate dihydrate, sucrose and / or trehalose, bovine serum albumin, ethylenediaminetetraacetic acid, dithiothreitol and preservative into water and fully dissolving, then adding surfactant and adjusting pH to be acidic, and finally adding urease; wherein the final concentrations of potassium dihydrogen phosphate, disodium hydrogen phosphate dihydrate, sucrose / trehalose, bovine serum albumin, ethylenediaminetetraacetic acid, dithiothreitol, preservative, surfactant and urease in the reaction reagents are respectively 0.05-0.5 mM, 0.05-0.5 mM, 2.5-50 mM, 1-5 muM, 1-5 muM, 0.5-5 mM, 5-10 mM, 0.5-2 muM and 10-50 KU / L.

8. The test paper according to claim 5 or 7, characterized in that The pH value of the reaction reagents is kept between 4.5 and 6.

5.

9. The test paper according to claim 1, characterized by The diffusion area is formed by arranging dispersion reagents on the base material.

10. The test paper according to claim 9, characterized in that The dispersion reagents comprise dispersion agent; wherein the final concentration of the dispersion agent is 0.5%-1.5%.

11. The test paper according to claim 10, characterized in that The dispersion reagents further comprise enzyme inhibitor and sodium chloride.

12. The test strip of claim 10, wherein, The dispersion reagents are prepared by adding sorbitol into water to a final concentration of 0.5%-1.5%.

13. The test paper according to claim 1, characterized by The base material of the color developing area comprises NC membrane, PES membrane, PVDF membrane, cellulose acetate membrane, mixed cellulose membrane, water absorption paper or filter paper.

14. The test paper according to claim 1, characterized by The color developing area is formed by arranging pre-prepared color developing reagents on the base material.

15. The test strip of claim 14, wherein, The color developing reagents comprise buffer, color developing substance, preservative and surfactant.

16. The test strip of claim 15, wherein, The color developing reagent is prepared by adding citric acid monohydrate, sodium citrate dihydrate, phenol red, and a preservative into water, dissolving them thoroughly, adding a surfactant, and adjusting the pH to be acidic; wherein the final concentrations of citric acid monohydrate, sodium citrate dihydrate, phenol red, the preservative, and the surfactant in the color developing reagent are 0.05-0.5 mM, 0.05-0.5 mM, 1-5 mM, 5-10 mM, and 0.5-2 μM, respectively.

17. The test strip of claim 14 or 16, wherein, The pH value of the color developing reagent is maintained between 2.5 and 5.

5.

18. The test paper according to claim 1, characterized by The test paper further comprises a protective layer covering any one or more of the reaction zone, the diffusion zone, and the color developing zone.

19. The test strip of claim 18, wherein, The protective layer is formed by disposing a protective reagent on any one or more of the reaction zone, the diffusion zone, and the color developing zone.

20. The test strip of claim 19, wherein, The protective reagent comprises a buffer and a film forming agent.

21. The test strip of claim 20, wherein, The protective reagent is prepared by adding potassium dihydrogen phosphate and disodium hydrogen phosphate dihydrate into water, dissolving them thoroughly, adjusting the pH to be acidic, and then adding a film forming agent; wherein the final concentrations of potassium dihydrogen phosphate, disodium hydrogen phosphate dihydrate, and the film forming agent in the protective reagent are 0.05-0.5 mM, 0.05-0.5 mM, and 0.5%-1.5%, respectively.

22. The test strip of claim 20, wherein The film forming agent comprises chitosan, chitosan quaternary ammonium salt, carboxymethyl chitosan, starch, modified starch, chondroitin sulfate, keratin, silk protein, cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, konjac glucomannan, dextran, alginate, carrageenan, xanthan gum, gum arabic, poloxamer, polyethylene glycol, polylactic acid, polylysine, polyglycolide, polyvinyl alcohol, polyacrylonitrile, or polyvinylpyrrolidone.

23. The test strip of claim 21, wherein The pH value of the protective reagent is maintained between 4.5 and 6.

5.

24. The test strip of claim 1, wherein The length of the sampling zone is between 15 mm and 30 mm.

25. The test strip of claim 1, wherein The lengths of the reaction zone, the diffusion zone, and the color developing zone are between 5 mm and 15 mm.

26. The test strip of claim 24 or 25, wherein, The widths of the sampling zone, the reaction zone, the diffusion zone, and the color developing zone are between 3 mm and 5 mm.

27. The test strip of claim 1, wherein The diffusion zone, the reaction zone, and the color developing zone are formed on different substrates, and the diffusion zone is located between the reaction zone and the color developing zone to spatially separate the reaction zone and the color developing zone.

28. The test strip of claim 27, wherein, The sampling zone, the reaction zone, the diffusion zone, and the color developing zone are attached to a base layer by an adhesive on the base layer.

29. The test strip of claim 27, wherein The sampling zone, the reaction zone, the diffusion zone, and the color developing zone are sequentially and overlappingly arranged on the base layer to form a liquid passage through the overlapping areas.

30. The test strip of claim 29, wherein, The length of the overlapping area is 1-2 mm.

31. The test strip of claim 1, wherein The reaction zone, the diffusion zone, and the color developing zone are sequentially formed on different areas of the same substrate.

32. The test strip of claim 27 or 31, wherein, The test paper further comprises a cover plate arranged at the proximal end of the color developing zone; wherein the cover plate is made of a non-water-absorbing material.

33. A kit for detecting urea in a body fluid, characterized by The test paper comprises: a housing having an internal space, a first window located at the distal end of the housing, and a second window away from the first window; a base layer arranged in the internal space; a sampling zone arranged at the distal end of the base layer and used to absorb a body fluid to be detected through the first window; a reaction zone disposed on the base layer for absorbing the body fluid in the sampling zone to react with urease in the reaction zone; a diffusion zone disposed on the base layer and in communication with a proximal end of the reaction zone for laterally transferring reactants of the reaction zone; a color development zone disposed on the base layer corresponding to the second window and isolated from the reaction zone by the diffusion zone, for absorbing the reactants laterally transferred from the diffusion zone to react with color development substances in the color development zone to display the detection result of urea in the body fluid through the second window.

34. A method for detecting urea in a body fluid, characterized by, The method comprises: acquiring a detection image obtained by photographing the test paper or the kit using an image capturing device; wherein the detection image is photographed within a reading time window after the test paper or the kit absorbs the body fluid to be detected, and the detection image includes an image of the color development zone; determining color development data corresponding to the image of the color development zone based on the detection image; determining the urea concentration of the body fluid based on the color development data and a standard curve corresponding to the test paper or the kit.

35. The method for detecting a body fluid urea according to claim 34, characterized by, The method further comprises the step of acquiring batch information of the test paper or the kit to determine the standard curve corresponding to the batch information.

36. The method for detecting a body fluid urea according to claim 34, wherein, The method further comprises the step of determining evaluation information of the user according to the determined urea concentration of the body fluid and the type of the body fluid.

37. A system for detecting urea in a bodily fluid, comprising: The method comprises: an acquisition module configured to acquire a detection image obtained by photographing the test paper or the kit using an image capturing device; wherein the detection image is photographed within a reading time window after the test paper or the kit absorbs the body fluid to be detected, and the detection image includes an image of the color development zone; a color development data determination module configured to determine color development data corresponding to the image of the color development zone based on the detection image; a concentration determination module configured to determine the urea concentration of the body fluid based on the color development data and a standard curve corresponding to the test paper or the kit.

38. A computer device, comprising: The method comprises: a storage device configured to store at least one program; a processing device connected to the storage device and configured to invoke the at least one program from the storage device and execute the at least one program to implement the method for detecting urea in a body fluid according to any one of claims 34 to 36.

39. A computer-readable storage medium, characterized in that, A computer program product is stored in a computer readable storage medium, and when the computer program product is run on a computer, the computer is caused to execute the method for detecting urea in a body fluid according to any one of claims 34 to 36.

40. A computer program product, characterised in that, ​

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