A portable chromatographic detection device and its application

Abstract

The application discloses a portable chromatographic detection device and application thereof, and belongs to the technical field of detection devices. The device comprises a top cover, a base, a test strip and a flexible PCB circuit board. The test strip comprises a sample pad, a binding pad, a nitrocellulose membrane, a water absorption pad and a supporting back plate. The nitrocellulose membrane has a patterned electrode as an electric channel, and is divided into a clamping area and a detection area for solution flow. The clamping area is connected with the flexible PCB circuit board through a magnetic attraction connector. One end of the detection area is connected with the water absorption pad in a top-overlapping manner, the other end of the detection area is connected with the binding pad in a top-overlapping manner, and the other end of the binding pad is connected with the sample pad in a top-overlapping manner. Hollow windows are formed in the top cover at the sample pad and the nitrocellulose membrane. The detection device is convenient to carry, has various functions, is high in sensitivity and integration, can be used in combination with computers, mobile phones and other equipment, and is particularly suitable for use in families, fields and other places.

Description

Technical Field

[0001] This invention belongs to the field of detection device technology, specifically relating to a portable, multifunctional, highly sensitive and integrated chromatography detection device. Background Technology

[0002] In recent years, with the increasing awareness of health, traditional testing methods based on large-scale instruments have struggled to meet the demand for large-scale, rapid testing, and are also incompatible with the uneven distribution of medical resources in my country. Therefore, miniaturized, low-cost, and rapid testing methods, such as point-of-care testing (POC), are gaining popularity. Colloidal gold-based test strips are one of the most commonly used POC platforms, but they currently primarily focus on qualitative and semi-quantitative detection, lacking accurate quantification and exhibiting low sensitivity. Electrochemical detection, due to its simplicity, high sensitivity, and real-time performance, can be used as a quantitative detection method in conjunction with test strips to achieve accurate quantification of target analytes.

[0003] Current electrochemical test strips all combine separate electrodes and test strips. For example, Chinese patent CN204731241U discloses an electrochemical blood test strip where electrodes are printed on an insulating substrate, which is then placed below a membrane to detect electrochemical signals. Wires and hydrophilic membranes are also stacked. This assembly method requires consideration of the fit between the electrodes and the test strip to ensure signal detection. Furthermore, the stacking method increases the complexity and cost of the device, affecting its repeatability. Similar Chinese patents such as CN 1908645A, CN102565153A, CN 103175871B, and CN 111781351A all suffer from this deficiency.

[0004] Miniaturized and low-cost detection methods rely on portable detection tools. Chaiyo et al. implemented smartphone-based electrochemical test strip detection, inserting the electrodes into a USB-type portable electrochemical analyzer, and then relying on the mobile phone for power and signal processing for on-site real-time detection (Anal. Chem. 2022, 94, 2554-2560). However, this method can damage the paper-based electrodes, affecting signal reading, thus necessitating the development of new connection methods. The new connection method secures the test strip while ensuring stable electrochemical analysis and stable electrochemical signal reading. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a portable chromatography detection device and its application. The detection device of this invention is portable, multifunctional, highly sensitive and integrated, and can be used with devices such as computers and mobile phones, making it particularly suitable for use in homes, fields, and other locations.

[0006] The specific technical solution adopted in this invention is as follows:

[0007] In a first aspect, the present invention provides a portable chromatography detection device, comprising a top cover, a base, a test strip, and a flexible PCB circuit board; the top cover and the base together form a shell structure with a hollow inner cavity, and the test strip is detachably located in the hollow inner cavity;

[0008] The test strip includes a sample pad, a conjugate pad, a nitrocellulose membrane, an absorbent pad, and a support backplate. The sample pad, conjugate pad, nitrocellulose membrane, and absorbent pad are all fixed to the base by the support backplate. The nitrocellulose membrane has patterned electrodes as electrical channels and is divided into a clamping area and a detection area for solution flow. The clamping area is connected to a flexible PCB circuit board via a magnetic connector. One end of the detection area is overlapped and attached to the top of an absorbent pad, and the other end is overlapped and attached to the top of a conjugate pad. The other end of the conjugate pad is overlapped and attached to the top of a sample pad. The top cover has perforated windows at the sample pad and the nitrocellulose membrane, respectively.

[0009] Preferably, the base also has a battery fixed on it for powering the flexible PCB circuit board.

[0010] Preferably, the nitrocellulose membrane is divided into a clamping area and a detection area by a hydrophobic material, with the clamping area located on both sides and the detection area located in the middle; the clamping areas on both sides are connected by a back strap of the male and female ends of a magnetic connector.

[0011] Preferably, the inner side of the base is provided with a slot for fixing the test strip, magnetic connector and flexible PCB circuit board.

[0012] Preferably, the patterned electrode includes one or more working electrodes, a set of counter electrodes and a reference electrode, and the pattern of the working electrode at least covers the detection line of the test strip.

[0013] Furthermore, the working electrode pattern also covers the control lines of the test strip.

[0014] Preferably, the flexible PCB circuit board can support electrical analysis methods such as cyclic voltammetry, chronoamperometry, differential pulse voltammetry, ampere method, charge method, and line scan voltammetry.

[0015] Preferably, the sample pad is made of glass fiber or polyester fiber, the binding pad is made of glass fiber with the target detection signal material deposited on it, and the absorbent pad is made of polyester fiber.

[0016] Preferably, the test strip can perform detection methods such as electrical signal detection, electrochromic reaction, and electrochemiluminescence.

[0017] Secondly, the present invention provides an application of the portable chromatography detection device as described in any of the first aspects in the fields of immunoassay, environmental detection, food detection and health monitoring.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. The device is compatible with test strips with membrane electrodes, effectively fixing the test strips without damaging the membrane electrodes, achieving efficient and stable electrochemical analysis with analytical results comparable to those of an electrochemical workstation; 2. The device is portable, versatile, highly sensitive, and integrated; 3. The device has a wide range of applications, including immunoassay, environmental monitoring, food testing, and health monitoring. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of one embodiment of the portable chromatography detection device of the present invention;

[0021] The attached figures are labeled as follows: 1. Top cover; 2. Sample pad; 3. Binding pad; 4. Nitrocellulose membrane; 5. Support backplate; 8. Water-absorbing pad; 6. Magnetic connector; 7. Flexible PCB circuit board; 9. Base; 10. Battery.

[0022] Figure 2 The image shows a cross-sectional view of the nitrocellulose electrode on the test strip in Example 1. a is the working electrode / counter electrode, and b is the reference electrode.

[0023] Figure 3 The cyclic voltammetric response of the test strip in Example 2 to 0.5 mmol / L methanol ferrocene (solvent is 0.1 mol / L potassium chloride) in an electrochemical workstation (solid line) and a flexible PCB circuit board (dashed line).

[0024] Figure 4 The curve shows the sensitive response of the device in Example 3 to low concentrations of rabbit IgG. Detailed Implementation

[0025] The present invention will be further described and illustrated below with reference to the accompanying drawings and specific embodiments. The technical features of each embodiment of the present invention can be combined accordingly, provided that there is no mutual conflict.

[0026] like Figure 1 The diagram illustrates a portable chromatography detection device provided by this invention. The device mainly comprises a top cover 1, a base 9, a test strip, and a flexible PCB circuit board 7. The top cover 1 and the base 9 together form a shell structure with a hollow inner cavity, and the test strip is detachably located within the hollow inner cavity. Specifically, the top cover 1 and the base 9 can be completely assembled to form a relatively sealed hollow inner cavity.

[0027] In the device of this invention, the test strip mainly includes a sample pad 2, a conjugate pad 3, a nitrocellulose membrane 4, an absorbent pad 8, and a support backing plate 5. The sample pad 2, conjugate pad 3, nitrocellulose membrane 4, and absorbent pad 8 are all disposed on the same surface of the support backing plate 5, and the other side of the support backing plate 5 is used to adhere and fix it to the inner surface of the base 9. The nitrocellulose membrane 4 has specific patterned electrodes that can serve as electrical channels; these channels are divided into a clamping area and a detection area for solution flow. The clamping area is connected to a flexible PCB circuit board 7 via a magnetic connector 6. One end of the detection area is top-overlapped with the absorbent pad 8, and the other end is top-overlapped with the conjugate pad 3. The other end of the conjugate pad 3 is top-overlapped with the sample pad 2. That is, the sample pad 2 and the conjugate pad 3, the conjugate pad 3 and the nitrocellulose membrane 4, and the nitrocellulose membrane 4 and the absorbent pad 8 are all partially adhered and overlapped. Hollow windows are provided on the top cover 1 at the sample pad 2 and the nitrocellulose membrane 4 for adding solution or observation.

[0028] In this embodiment, the flexible PCB circuit board 7 has wireless transceiver functionality and can support various electroanalytical methods. The circuit uses a strap-type fixation method for the test strip, and the two are connected via a magnetic connector. By simply replacing test strips with different functions, quantitative detection of different target substances can be achieved. Specifically, the electrode pattern on the nitrocellulose membrane 4 is divided into a clamping area and a detection area by a hydrophobic material to determine the electrode area and restrict the solution flow area. The clamping areas are located on both sides and are used to connect the magnetic connector 6. They do not flow through the solution, ensuring that the electrodes in the clamping areas only serve a conductive function. The detection area is located in the middle and is used for solution flow. The clamping areas on both sides are connected via a strap-type connection using the male and female ends of the magnetic connector 6. The magnetic connector 6 can contact the clamping areas in the electrode pattern of the test strip and conduct electrical channels. The hydrophobic material here can be wax, hydrophobic ink, polydimethylsiloxane, etc.

[0029] As a preferred embodiment, the flexible PCB circuit board 7 should be able to meet the following electrical analysis methods: cyclic voltammetry, chronoamperometry, differential pulse voltammetry, ammeter method, charge method, and line scan voltammetry.

[0030] In this embodiment, a battery 10 for powering the flexible PCB circuit board 7 is also fixed on the base 9. The inner side of the base 9 has slots for fixing the test strip, magnetic connector 6, and flexible PCB circuit board 7. This is to fix the circuit board on the base, simplifying the steps when using the device and increasing its portability. The flexible PCB circuit board 7 is designed with specific channels for soldering the magnetic connector 6. During use, the magnetic connector is first disconnected, then the test strip is placed in the test strip placement slot on the base, and then the magnetic connector is aligned with the electrodes and closed, thus completing the connection between the circuit board and the electrodes. This "strap-style" connection effectively reduces wear on the membrane electrodes and secures the test strip, facilitating accurate signal measurement. After the required reaction is completed, an electroanalysis method command is sent to the flexible PCB circuit board 7 via a computer or mobile phone. The electrical signal received from the flexible PCB circuit board 7 allows for quantitative analysis of the required reaction.

[0031] In this embodiment, the patterned electrode includes one or more working electrodes, a set of counter electrodes and a reference electrode, and the pattern of the working electrode should at least cover the detection line of the test strip. Of course, the pattern of the working electrode may also cover the control line of the test strip.

[0032] In this embodiment, the sample pad 2 is preferably made of glass fiber or polyester fiber; the binding pad 3 is preferably made of glass fiber with a target detection signal substance deposited on it. For example, when detecting rabbit IgG, the deposited substance is rabbit IgG antibody labeled with horseradish peroxidase; the absorbent pad 8 is preferably made of polyester fiber.

[0033] The test strips of this invention can achieve detection methods including electrical signal detection, electrochromic, and electrochemiluminescence. The portable chromatographic detection device of this invention can be applied in fields such as immunoassay, environmental monitoring, food testing, and health monitoring.

[0034] Example 1

[0035] This example illustrates the manufacturing process of the test strips used in this portable chromatography detection device, as follows:

[0036] A 2.5 × 10 cm nitrocellulose membrane 4 was used, and wax-etched templates, working electrode / counter electrode stencils, and reference electrode stencils of corresponding sizes were designed. First, liquid wax was rapidly printed onto the nitrocellulose membrane 4 using the wax-etched template at 65°C. After cooling and curing, silver / silver chloride ink was screen-printed onto the membrane as the reference electrode. After air drying, carbon conductive ink was finally printed onto the membrane as the working electrode / counter electrode, and the membrane was allowed to stand for 30 minutes. The resulting cross-sectional views of the working electrode / counter electrode and the reference electrode are shown below. Figure 2As shown in a and b, conductivity is achieved without affecting the chromatography of the solution. The desired antibody is then applied to the working electrode area and dried at 37°C for 5 hours. After drying, the 2.5 × 10 cm membrane is cut into identical 2.5 × 2.5 cm pieces, with the pattern as shown. Figure 1 The nitrocellulose membrane 4 is shown in the diagram. Finally, the 1×2cm sample pad 2, the 1×1cm binding pad 3 with detection antibody, the 1×3.2cm absorbent pad 8, and the 2.5×2.5cm nitrocellulose membrane are assembled onto the support backing plate 5 to obtain the following result: Figure 1 The test strip shown.

[0037] Example 2

[0038] This example illustrates the response of the test strip in Example 1 to electrochemically active substances and the feasibility of a portable chromatography detection device.

[0039] Take the test strip from Example 1, and add 200 μL of 0.5 mmol / L ferrocene methanol to the sample pad 2 area. After 5 minutes, the solution completely wets the three electrodes through chromatography. At this point, clamp the electrodes in the clamping area with alligator clips and start the cyclic voltammetry detection program on the electrochemical workstation to record the curve. The result is as follows: Figure 3 The result of the solid line shows a clear redox signal, good peak shape, and small peak-to-peak difference, indicating that the prepared test strip responds well to electrochemically active substances. Then, the portable chromatography detection device was replaced, and the electrodes in the clamping area were clipped using the magnetic connector 6. Cyclic voltammetry detection program instructions and received signals were input into the computer. The results, after simple calibration, are as follows: Figure 3 The results shown by the dashed line indicate that the curve largely overlaps with the solid line, demonstrating a clear redox signal, good peak shape, and small peak-to-peak difference. This suggests that the portable chromatography detection device can replace the electrochemical workstation for detection. The above results indicate that the test strip in Example 1 has a good response to electrochemically active substances, and the results from the portable chromatography detection device are highly consistent with those from the electrochemical workstation, thus it can replace the electrochemical workstation for detection.

[0040] Example 3

[0041] This example illustrates how a portable chromatography detection device assembled using the test strips obtained in Example 1 can achieve a linear relationship between rabbit IgG antibody concentration and current, demonstrating the quantification capability of this device.

[0042] Rabbit IgG capture antibody was applied to the working electrode area of ​​the prepared nitrocellulose 4, and rabbit IgG detection antibody, labeled with horseradish peroxidase, was sprayed onto the binding pad 3. Other pads were then assembled to obtain a test strip for detecting rabbit IgG. The detection principle utilizes square wave voltammetry to measure the oxidation current signal of the 3,3',5,5'-tetramethylbenzidine / hydrogen peroxide / horseradish peroxidase system. As the concentration of rabbit IgG increases, the sandwich immunization of antigen and antibody increases the horseradish peroxidase content in the working electrode area, thus enhancing the oxidation peak current signal. Five rabbit IgG samples with different concentrations were detected using a portable chromatography detection device. The oxidation peak current was measured within the potential range of -0.2 to 0.8 V, using a step potential of 5 mV, a pulse potential of 50 mV, and a frequency of 50 Hz. Each sample was tested three times, and the sample concentration was compared with the corresponding oxidation current. Figure 4 The results showed that the oxidation current corresponding to 0–15 pg / mL rabbit IgG was approximately 3.46–8.00 μA, and the linear equation was y = 0.3049x + 3.4292 with R² = 0.9994, indicating that this portable chromatography device can achieve highly sensitive quantitative detection of low-concentration samples.

[0043] The detection device of the present invention has the advantages of being portable, having multiple functions, high sensitivity and integration, and can be used with devices such as computers and mobile phones, making it particularly suitable for use in homes, outdoors and other places.

[0044] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A portable chromatography detection device, characterized in that, It includes a top cover (1), a base (9), a test strip, and a flexible PCB circuit board (7); the top cover (1) and the base (9) together form a shell structure with a hollow inner cavity, and the test strip is detachably located in the hollow inner cavity; The test strip includes a sample pad (2), a conjugate pad (3), a nitrocellulose membrane (4), an absorbent pad (8), and a support backplate (5). The sample pad (2), the conjugate pad (3), the nitrocellulose membrane (4), and the absorbent pad (8) are all fixed to the base (9) by the support backplate (5). The nitrocellulose membrane (4) has patterned electrodes as electrical channels and is divided into a clamping area and a detection area for solution flow. The clamping area is connected to the flexible PCB circuit board (7) by a magnetic connector (6). The top of one end of the detection area is overlapped and attached to the absorbent pad (8), and the top of the other end is overlapped and attached to the conjugate pad (3). The top of the other end of the conjugate pad (3) is overlapped and attached to the sample pad (2). The top cover (1) has perforated windows at the sample pad (2) and the nitrocellulose membrane (4), respectively. The nitrocellulose membrane (4) is divided into a clamping area and a detection area by a hydrophobic material. The clamping area is located on both sides and the detection area is located in the middle. The clamping areas on both sides are connected by the male and female ends of the magnetic connector (6) in a strap-like manner. The patterned electrode includes one or more working electrodes, a set of counter electrodes and a reference electrode, and the working electrode pattern at least covers the detection line of the test strip.

2. The portable chromatography detection device according to claim 1, characterized in that, A battery (10) for powering the flexible PCB circuit board (7) is also fixed on the base (9).

3. The portable chromatography detection device according to claim 1, characterized in that, The base (9) has a slot on its inner side for fixing the test strip, magnetic connector (6) and flexible PCB circuit board (7).

4. The portable chromatography detection device according to claim 1, characterized in that, The working electrode pattern also covers the control lines of the test strip.

5. A portable chromatography detection device according to claim 1, characterized in that, The flexible PCB circuit board (7) can perform electrical analysis methods such as cyclic voltammetry, chronoamperometry, differential pulse voltammetry, amperometric method, charge method, and line scan voltammetry.

6. The portable chromatography detection device according to claim 1, characterized in that, The sample pad (2) is made of glass fiber or polyester fiber, the binding pad (3) is made of glass fiber with the target detection signal material deposited on it, and the absorbent pad (8) is made of polyester fiber.

7. A portable chromatography detection device according to claim 1, characterized in that, The test strip can perform detection methods including electrical signal detection, electrochromic reaction, and electrochemiluminescence.

8. The application of a portable chromatography detection device as described in any one of claims 1 to 7 in the fields of immunoassay, environmental detection, food detection, and health monitoring.

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