Electrochemical detection test paper and method for judging whether sample size is sufficient or not

Abstract

The invention provides electrochemical detection test paper and a method for judging whether the sample size is sufficient or not, the electrochemical detection test paper comprises a test paper carrier, a PET base material, an electrode system, a reaction chamber and an insulating layer are arranged on the surface of one side of the test paper carrier, the electrode system is arranged on the surface of the PET base material, a sample inlet is formed in the insulating layer and connected with the reaction chamber, and the electrode system is connected with the reaction chamber. The electrode system comprises a third electrode, a working electrode and a counter electrode which are sequentially arranged at intervals, the insulating layer covers the third electrode, the working electrode and the counter electrode, the two ends of the third electrode, the two ends of the working electrode and the two ends of the counter electrode are aligned and arranged in parallel, and the distances between the working electrode and the third electrode and between the working electrode and the counter electrode are the same. The third electrode, the working electrode and the counter electrode penetrate through the reaction chamber, and the middle parts of the third electrode, the working electrode and the counter electrode are positioned in the reaction chamber. The electrochemical detection test paper is low in manufacturing cost and can accurately and quickly judge whether the sample size to be detected is sufficient or not.

Description

Technical Field

[0001] The invention belongs to the technical field of medical testing, and relates to an electrochemical test paper and a method for judging whether a sample amount is sufficient. Background Art

[0002] Electrochemical test strips are test strips that use electrochemical principles for detection. They have the advantages of fast detection speed, easy use, and low cost. They are widely used in environmental protection, medical care, food safety and other fields. At present, blood glucose test strips, uric acid test strips, blood ketone test strips and other test strips for home or hospital testing are common on the market. Because they can be used at home, users may not be familiar with the operation, resulting in insufficient sample addition, resulting in incorrect test results. Therefore, how to judge whether the test sample volume is sufficient is a key issue that needs to be solved urgently.

[0003] CN113588748A discloses an electrochemical test paper triggered by full blood, wherein the electrochemical test paper triggered by full blood has a full blood electrode located at one end away from the sampling port of the reaction zone. When the blood is sucked into the reaction zone and fills the reaction zone, the full blood trigger electrode will be turned on before the detection begins. If the blood is not fully absorbed, the full blood trigger electrode will not be turned on, and it will be prompted that the blood is not fully absorbed. This can completely avoid the risk of being misled by inaccurate test results during the test because the blood is not fully absorbed and not noticed. However, due to capillary action, it may happen that the two ends of the sample have contacted the third electrode, but the middle end does not completely cover the working electrode. At this time, the full blood electrode will also be triggered to turn on, thereby giving an erroneous result of sufficient sample addition. When the blood is sucked in, the current is detected to determine whether the blood is fully absorbed, which is easily affected by the enzyme membrane state or the concentration of the sample to be tested. When the sample to be tested is 0, the current signal is close to the background noise, and the current is not easy to change, which will give an erroneous judgment of insufficient sample addition.

[0004] CN114935599A discloses a method for judging whether the amount of added sample is sufficient and a method for measuring the concentration of analytes in a sample to be tested. The method for judging whether the amount of added sample is sufficient comprises the following steps: S1: connecting the electrochemical test paper to the electronic detection system and adding the sample; S2: applying alternating current between the working electrode and the counter electrode to obtain impedance Z1; S3: applying alternating current between the fourth electrode and the third electrode to obtain impedance Z2; S4: when the absolute value of the impedance deviation or the absolute value of the impedance deviation rate is greater than a preset value, it is judged that the amount of added sample does not meet the sample amount required for detection; when the absolute value of the impedance deviation or the absolute value of the impedance deviation rate is less than or equal to the preset value, it is judged that the amount of added sample meets the sample amount required for detection. The method requires many electrodes, has high preparation cost, is complicated to prepare, and is susceptible to the problem of impedance test deviation caused by unstable printing quality. Summary of the invention

[0005] The object of the present invention is to provide an electrochemical test strip and a method for judging whether the sample amount is sufficient. The electrochemical test strip of the present invention is only provided with three electrodes, which greatly reduces the cost and can accurately and quickly judge whether the sample amount to be tested is sufficient, thereby solving the problem that if the amount of sample added does not completely cover the content required by the detection system, the detection system will give an inaccurate result, thereby making an incorrect judgment on the patient's condition.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides an electrochemical test paper, the electrochemical test paper comprising a test paper carrier, a polyethylene terephthalate substrate, i.e., a PET substrate, an electrode system, a reaction chamber and an insulating layer are arranged on one side surface of the test paper carrier, the electrode system is arranged on the surface of the polyethylene terephthalate substrate, an injection port is arranged on the insulating layer, the injection port is connected to the reaction chamber, the electrode system comprises a third electrode, a working electrode and a counter electrode arranged in sequence, the insulating layer covers the third electrode, the working electrode and the counter electrode, the counter electrode is arranged at one end away from the injection port, and the two ends of the third electrode, the working electrode and the counter electrode are respectively aligned and arranged in parallel, the distance between the working electrode and the third electrode and the counter electrode is the same, and the reaction chamber covers the middle part of the third electrode, the working electrode and the counter electrode.

[0008] The reaction chamber of the present invention covers the middle part of the third electrode, the working electrode and the counter electrode, that is, the third electrode, the working electrode and the counter electrode pass through the reaction chamber, and the middle part of the third electrode, the working electrode and the counter electrode is located in the reaction chamber.

[0009] When the test strip is working, the sample to be tested is added to the sample inlet. Due to the capillary siphon effect of the test strip, the sample will enter the reaction zone and a corresponding reaction will occur in the reaction zone. When the amount of sample added does not completely cover the content required by the detection system, the detection system will give an inaccurate result, thereby making an incorrect judgment on the patient's condition. The electrochemical test strip of the present invention can accurately and quickly judge whether the sample amount is sufficient by calculating the difference between the ratio of the phase angle value between the working electrode and the counter electrode and between the third electrode and the working electrode and the preset value, thereby improving the accuracy of the detection system.

[0010] Preferably, the electrode system further comprises a third electrode pin, a working electrode pin and a counter electrode pin.

[0011] Preferably, the third electrode pin, the working electrode pin and the counter electrode pin are respectively arranged at one end of the electrode system away from the injection port.

[0012] Preferably, wires are respectively arranged between the third electrode pin and the third electrode, between the working electrode pin and the working electrode, and between the counter electrode pin and the counter electrode.

[0013] Preferably, the material of the wire includes any one of conductive silver, gold or carbon, or a combination of at least two of them.

[0014] Preferably, the materials of the working electrode, the third electrode and the counter electrode independently include any one of conductive silver, gold or carbon, or a combination of at least two of them.

[0015] Preferably, the working electrode, the third electrode and the counter electrode are respectively prepared by printing a conductive paste on a polyethylene terephthalate substrate.

[0016] Preferably, the reaction reagents include any one or a combination of at least two of a target substance-specific enzyme, a stabilizer, a buffer, a surfactant or an electron mediator. Typical but non-limiting combinations include a combination of a target substance-specific enzyme and an electron mediator, a combination of a stabilizer and an electron mediator, or a combination of a target substance-specific enzyme and a surfactant, etc.

[0017] Preferably, the stabilizer includes any one of trehalose, sorbitol, sodium glutamate or silk protein, or a combination of at least two of them, preferably trehalose.

[0018] Preferably, the buffer comprises Good's buffer solution, organic acid buffer solution or phosphate buffer solution, preferably phosphate buffer solution.

[0019] Preferably, the surfactant comprises any one of saponin, dodecyl sulfate, cetyltrimethylammonium bromide or Triton or a combination of at least two thereof, preferably Triton.

[0020] Preferably, the electron mediator includes any one of potassium ferrocyanide, hexaammonium ruthenium trichloride, tetrathiafulvalene or ferrocene, or a combination of at least two thereof, preferably hexaammonium ruthenium trichloride.

[0021] In a second aspect, the present invention provides a method for determining whether a sample size is sufficient, the method comprising the following steps:

[0022] (1) inserting the electrochemical test paper as described in the first aspect into the instrument and adding the sample to be tested into the instrument;

[0023] (2) applying a first alternating current between the working electrode and the counter electrode of the electrochemical test paper to obtain a first sample impedance phase angle value, and then applying a second alternating current between the third electrode and the working electrode of the electrochemical test paper to obtain a second sample impedance phase angle value;

[0024] (3) calculating the ratio of the first sample impedance phase angle value to the second sample impedance phase angle value, and judging whether the added test sample quantity meets the requirements of the test system according to the relationship between the ratio and the preset value;

[0025] If the amount of the added test sample does not meet the requirements of the test system, an error is reported; if the amount of the added test sample meets the requirements of the test system, the next step is performed;

[0026] (4) A direct current is applied between the working electrode and the counter electrode, and a corresponding current is obtained according to the reaction. The concentration value of the detected substance contained in the final sample is obtained by conversion.

[0027] In the method described in the present invention, an alternating current is applied to a working electrode and a counter electrode, and a first impedance phase angle value is measured. After a preset time, an alternating voltage is applied to a third electrode and a working electrode, and a second impedance phase angle value between the third electrode and the working electrode is measured. When the required sample amount for detection is insufficient, the sample to be tested cannot reach the counter electrode or the sample only covers a very small part of the counter electrode. Since the insufficient sample amount will cause a change in the sample impedance phase angle value, the two impedance phase angle values ​​differ greatly. When the ratio between the first impedance phase angle value and the second impedance phase angle value is greater than a preset value, for example, the set value is 105%, the instrument gives an error code for insufficient sample amount. When the required sample amount is sufficient, within a preset time, the sample covers all electrodes, and at this time, the difference between the first impedance phase angle value measured between the counter electrode and the working electrode and the second impedance phase angle value measured between the working electrode and the counter electrode is very small.

[0028] Preferably, the instrument in step (1) includes a blood glucose detector, a uric acid detector, a blood ketone detector or a creatinine detector, etc.

[0029] The instruments described in the present invention include but are not limited to the above-mentioned detectors. All instruments based on electrochemical detection methods can use the electrochemical detection test paper and the method for judging whether the sample amount is sufficient described in the present invention.

[0030] Preferably, the sample to be tested in step (1) includes any substance based on electrochemical detection, including but not limited to blood glucose, uric acid, blood ketones or creatinine.

[0031] Preferably, in step (2), the voltage of the first alternating current is 8 mV to 10 mV, for example, 8 mV, 8.5 mV, 9 mV, 9.5 mV or 10 mV.

[0032] Preferably, in step (2), the frequency of the first alternating current is 0.5-1.5 kHz, for example, 0.5 kHz, 0.8 kHz, 1 kHz, 1.2 kHz or 1.5 kHz.

[0033] Preferably, the time for applying the first alternating current in step (2) is 0.5 to 1.5 s, for example, 0.5 s, 0.8 s, 1 s, 1.2 s or 1.5 s, etc., and is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] Preferably, in step (2), the voltage of the second alternating current is 8 mV to 10 mV, for example, 8 mV, 8.5 mV, 9 mV, 9.5 mV or 10 mV.

[0035] Preferably, in step (2), the frequency of the second alternating current is 0.5-1.5 kHz, for example, 0.5 kHz, 0.8 kHz, 1 kHz, 1.2 kHz or 1.5 kHz.

[0036] Preferably, the time for applying the second alternating current in step (2) is 0.5 to 1.5 s, for example, 0.5 s, 0.8 s, 1 s, 1.2 s or 1.5 s, etc., and is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0037] Preferably, the preset value in step (3) is ≤105%.

[0038] Preferably, in step (3), if the ratio of the first sample impedance phase angle value to the second sample impedance phase angle value is greater than a preset value, the amount of added detection samples is insufficient.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] (1) The electrochemical test strip of the present invention uses the impedance phase angle of the blood sample, which can avoid the problem of misjudgment caused by impedance test deviation due to unstable printing quality, and can accurately and quickly determine whether the amount of the sample to be tested is sufficient.

[0041] (2) The method for judging whether the sample volume is sufficient according to the present invention requires fewer electrodes, has low cost, is simple to prepare, requires less sample volume, and can alleviate the pain of patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the structure of the electrochemical detection test paper provided by the embodiment of the present invention.

[0043] Among them, 1 is a PET substrate, 2-1 is a third electrode, 2-2 is a working electrode, 2-3 is a counter electrode, 2-4 is a third electrode pin, 2-5 is a working electrode pin, 2-6 is a counter electrode pin, 2-7 is a silver wire, 3 is a reaction chamber, 3-1 is a reaction reagent, 4 is an insulating layer, and 4-1 is an injection port. DETAILED DESCRIPTION

[0044] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0045] Example 1

[0046] This embodiment provides an electrochemical test paper. The structural schematic diagram of the electrochemical test paper is as follows: Figure 1 As shown, the electrochemical test paper includes a test paper carrier, and a PET substrate 1, an electrode system (including a third electrode 2-1, a working electrode 2-2, a counter electrode 2-3, a third electrode pin 2-4, a working electrode pin 2-5, a counter electrode pin 2-6 and a silver wire 2-7), a reaction chamber 3 and an insulating layer 4 are arranged on one side of the test paper carrier, wherein: Figure 1 The edges of the PET substrate 1 and the insulating layer 4 can completely overlap, and the edge range of the insulating layer 4 can also be smaller than the edge range of the PET substrate 1. It is only necessary to completely cover the third electrode 2-1, the working electrode 2-2 and the counter electrode 2-3 of the electrode system. In order to distinguish them in the figure, the edge range of the insulating layer 4 is smaller than the edge range of the PET substrate;

[0047] The electrode system is arranged on the surface of the PET substrate 1, the insulating layer 4 covers the third electrode 2-1, the working electrode 2-2 and the counter electrode 2-3, the insulating layer is provided with an injection port 4-1, and the injection port 4-1 is connected to the reaction chamber 3, the electrode system comprises the third electrode 2-1, the working electrode 2-2 and the counter electrode 2-3 arranged in sequence, the counter electrode 2-3 is arranged at one end away from the injection port 4-1, the third electrode 2-1, the working electrode 2-2 and the counter electrode 2-3 are the same in size, and the two ends of the third electrode 2-1, the working electrode 2-2 and the counter electrode 2-3 are respectively aligned and arranged in parallel, the distance between the working electrode 2-2 and the third electrode 2-1 and the counter electrode 2-3 is the same, and the reaction chamber 3 covers the middle part of the third electrode 2-1, the working electrode 2-2 and the counter electrode 2-3;

[0048] The third electrode 2-1, the working electrode 2-2 and the counter electrode 2-3 are all carbon electrodes;

[0049] The electrode system also includes a third electrode pin 2-4, a working electrode pin 2-5 and a counter electrode pin 2-6, and silver wires 2-7 are respectively arranged between the third electrode pin 2-4 and the third electrode 2-1, between the working electrode pin 2-5 and the working electrode 2-2, and between the counter electrode pin 2-6 and the counter electrode 2-3;

[0050] The reaction chamber 3 is provided with reaction reagents 3-1, including hexaammineruthenium trichloride, phosphate buffer, glucose dehydrogenase, Triton and trehalose.

[0051] Application Example 1

[0052] This application example uses the electrochemical test strip described in Example 1 to perform blood glucose testing. The blood glucose concentration of the sample is 5mmol / L, and the hematocrit is 20%. 10 groups of blood that meet the test requirements and 10 groups of blood that do not meet the test requirements are added. The test steps are as follows:

[0053] (1) Insert the electrochemical test strip into the blood glucose meter and add the sample after the meter displays the addition of sample;

[0054] (2) applying an alternating current of 9 mV and 1 kHz between the working electrode and the counter electrode for 1 second to obtain a first sample impedance phase angle value corresponding to the sample; after a set time, applying an alternating current of 9 mV and 1 kHz between the third electrode and the working electrode for 1 second to obtain a second sample impedance phase angle value corresponding to the sample;

[0055] (2) Calculate the ratio of the first sample impedance phase angle value to the second sample impedance phase angle value, and determine whether the added test sample volume meets the test system requirements based on the relationship between the ratio and the preset value (105%).

[0056] The ratio of the measured sample size to the impedance phase angle value is shown in Table 1:

[0057] Table 1

[0058]

[0059]

[0060] Application Example 2

[0061] The only difference between this application example and application example 1 is that the blood glucose concentration of the sample is 15mmol / L and the hematocrit is 20%. The other conditions and parameters are exactly the same as those in application example 1. The measured sample volume and impedance phase angle value ratio are shown in Table 2:

[0062] Table 2

[0063]

[0064]

[0065] Application Example 3

[0066] The only difference between this application example and application example 1 is that the blood glucose concentration of the sample is 25mmol / L and the hematocrit is 20%. The other conditions and parameters are exactly the same as those in application example 1. The measured sample volume and impedance phase angle value ratio are shown in Table 3:

[0067] Table 3

[0068]

[0069]

[0070] Application Example 4

[0071] The difference between this application example and application example 1 is that the blood glucose concentration of the sample is 5mmol / L and the hematocrit is 42%. The other conditions and parameters are exactly the same as those in application example 1. The measured sample volume and impedance phase angle value ratio are shown in Table 4:

[0072] Table 4

[0073]

[0074]

[0075] Application Example 5

[0076] The only difference between this application example and application example 1 is that the blood glucose concentration of the sample is 15mmol / L and the hematocrit is 42%. The other conditions and parameters are exactly the same as those in application example 1. The measured sample volume and impedance phase angle value ratio are shown in Table 5:

[0077] Table 5

[0078]

[0079]

[0080] Application Example 6

[0081] The only difference between this application example and application example 1 is that the blood glucose concentration of the sample is 25mmol / L and the hematocrit is 42%. The other conditions and parameters are exactly the same as those in application example 1. The measured sample volume and impedance phase angle value ratio are shown in Table 6:

[0082] Table 6

[0083]

[0084]

[0085] Application Example 7

[0086] The only difference between this application example and application example 1 is that the blood glucose concentration of the sample is 5mmol / L and the hematocrit is 70%. The other conditions and parameters are exactly the same as those in application example 1. The measured sample volume and impedance phase angle value ratio are shown in Table 7:

[0087] Table 7

[0088]

[0089]

[0090] Application Example 8

[0091] The only difference between this application example and application example 1 is that the blood glucose concentration of the sample is 15mmol / L and the hematocrit is 70%. The other conditions and parameters are exactly the same as those in application example 1. The measured sample volume and impedance phase angle value ratio are shown in Table 7:

[0092] Table 7

[0093]

[0094]

[0095] Application Example 9

[0096] The only difference between this application example and application example 1 is that the blood glucose concentration of the sample is 20mmol / L and the hematocrit is 70%. The other conditions and parameters are exactly the same as those in application example 1. The measured sample volume and impedance phase angle value ratio are shown in Table 9:

[0097] Table 9

[0098]

[0099]

[0100] It can be seen from Application Examples 1-9 that the method of the present invention can accurately and quickly determine whether the sample volume is sufficient, thereby improving the accuracy of the detection system.

[0101] Comparative application example 1

[0102] This comparative application example 1 uses the electrochemical test paper triggered by full blood described in CN113588748A and the test paper of the present invention to test the situation when both ends of the sample have contacted the third electrode, but the middle end does not completely cover the working electrode. The test results are shown in Table 10:

[0103] Table 10

[0104]

[0105]

[0106] From the comparison between Application Example 1 and Comparative Application Example 1, it can be seen that when both ends of the sample have contacted the third electrode but the middle end has not completely covered the working electrode, the prior art will produce an erroneous judgment result.

[0107] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. An electrochemical test paper, characterized in that: The electrochemical test paper comprises a test paper carrier; A polyethylene terephthalate substrate, an electrode system, a reaction chamber and an insulating layer are arranged on one side surface of the test paper carrier; The electrode system is arranged on the surface of the ethylene glycol terephthalate substrate; The electrode system comprises a third electrode, a working electrode and a counter electrode which are arranged in sequence and spaced apart, and the insulating layer covers the third electrode, the working electrode and the counter electrode; An injection port is arranged on the insulating layer, and the injection port is connected to the reaction chamber. The counter electrode is arranged at an end away from the injection port, and the two ends of the third electrode, the working electrode and the counter electrode are respectively aligned and arranged in parallel. The distance between the working electrode and the third electrode and the counter electrode is the same. The third electrode, the working electrode and the counter electrode pass through the reaction chamber, and the middle parts of the third electrode, the working electrode and the counter electrode are located in the reaction chamber.

2. The electrochemical test paper according to claim 1, characterized in that: The electrode system also includes a third electrode pin, a working electrode pin and a counter electrode pin; Wires are respectively arranged between the third electrode pin and the third electrode, between the working electrode pin and the working electrode, and between the counter electrode pin and the counter electrode; Preferably, the third electrode pin, the working electrode pin and the counter electrode pin are respectively arranged at one end of the electrode system away from the injection port; Preferably, the material of the wire includes any one of conductive silver, gold or carbon, or a combination of at least two of them.

3. The electrochemical test paper according to claim 1 or 2, characterized in that: The materials of the working electrode, the third electrode and the counter electrode independently include any one of conductive silver, gold or carbon or a combination of at least two thereof; Preferably, the working electrode, the third electrode and the counter electrode are respectively prepared by printing a conductive paste on a polyethylene terephthalate substrate.

4. The electrochemical test paper according to any one of claims 1 to 3, characterized in that: Reaction reagents are arranged in the reaction chamber; Preferably, the reaction reagents include any one or a combination of at least two of a target substance-specific enzyme, a stabilizer, a buffer, a surfactant or an electron mediator.

5. A method for determining whether a sample size is sufficient, characterized in that: The method comprises the following steps: (1) inserting the electrochemical test paper as described in any one of claims 1 to 4 into an instrument and adding a sample to be tested into the instrument; (2) applying a first alternating current between the working electrode and the counter electrode of the electrochemical test paper to obtain a first sample impedance phase angle value, and then applying a second alternating current between the third electrode and the working electrode of the electrochemical test paper to obtain a second sample impedance phase angle value; (3) calculating the ratio of the first sample impedance phase angle value to the second sample impedance phase angle value, and judging whether the added sample volume meets the requirements of the detection system according to the relationship between the ratio and the preset value; If the amount of samples added to be tested does not meet the requirements of the detection system, an error is reported; if the amount of samples added to be tested meets the requirements of the detection system, the next step is performed; (4) A direct current is applied between the working electrode and the counter electrode, and a corresponding current is obtained according to the reaction. The concentration value of the detected substance contained in the final sample is obtained by conversion.

6. The method according to claim 5, characterized in that The instrument in step (1) includes any one of a blood glucose detector, a uric acid detector, a blood ketone detector or a creatinine detector.

7. The method according to claim 5 or 6, characterized in that The sample to be tested in step (1) includes any one of blood glucose, uric acid, blood ketones or creatinine.

8. The method according to any one of claims 5 to 7, characterized in that: Step (2) The voltage of the first alternating current is 8 mV to 10 mV; Preferably, in step (2), the frequency of the first alternating current is 0.5 to 1.5 kHz; Preferably, the time for applying the first alternating current in step (2) is 0.5 to 1.5 seconds.

9. The method according to any one of claims 5 to 8, characterized in that: Step (2) The voltage of the second alternating current is 8mV to 10mV; Preferably, in step (2), the frequency of the second alternating current is 0.5 to 1.5 kHz; Preferably, the time for applying the second alternating current in step (2) is 0.5 to 1.5 seconds.

10. The method according to any one of claims 5 to 9, characterized in that: The preset value in step (3) is ≤105%; Preferably, in step (3), if the ratio of the first sample impedance phase angle value to the second sample impedance phase angle value is greater than a preset value, the amount of added detection samples is insufficient.

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