BIOSENSOR

Abstract

The present invention relates to a biosensor capable of determining whether the sample addition amount is sufficient. The biosensor at least comprises an insulating substrate, a working electrode and a fill detection electrode. The fill detection electrode is further away from the sample supply port of the biosensor than the working electrode, and the fill detection electrode is not in contact with a sample supply channel. The biosensor of the present invention can determine whether the sample amount added to the biosensor meets detection requirements, which effectively avoids the risk of insufficient sample amount and ensures the accuracy of test results.

Claims

1. A biosensor, comprising an insulating substrate, an sample supply channel, a working electrode and a fill detection electrode disposed on the insulating substrate, and a reagent layer covering at least the working electrode, wherein said fill detection electrode is further away from the sample supply port of the sample supply channel than the working electrode, and a gap is formed between the ends of both sides of the head of the fill detection electrode close to the sample supply port and the inner side wall of the sample supply channel.

2. The biosensor according to claim 1, wherein the ends of both sides of the tail of the fill detection electrode away from the sample supply port are in contact with the inner side wall of the sample supply channel.

3. The biosensor according to claim 1, wherein the fill detection electrode is not in contact with the inner side wall of the sample supply channel.

4. The biosensor according to claim 1, wherein said gap is set such that in the case where the added sample amount is the sample addition amount required by said biosensor, the working electrode in the sample supply channel is already completely covered by the sample when the sample contacts the fill detection electrode.

5. The biosensor according to claim 1, wherein the biosensor further comprises a counter electrode.

6. The biosensor according to claim 5, wherein the fill detection electrode is further away from the sample supply port of the sample supply channel than the working electrode and the counter electrode.

7. The biosensor according to claim 6, wherein the working electrode is closest to the sample supply port, and the counter electrode is disposed between the working electrode and the fill detection electrode.

8. The biosensor according to claim 6, wherein the counter electrode is closest to the sample supply port, and the working electrode is disposed between the counter electrode and the fill detection electrode.

9. The biosensor according to claim 5, wherein said gap is set such that in the case where the added sample amount is the sample addition amount required by said biosensor, the working electrode and the counter electrode in the sample supply channel are already completely covered by the sample when the sample contacts the fill detection electrode.

10. The biosensor according to claim 1, wherein the width of the sample supply channel ranges from 2 mm to 4 mm, and the width of the fill detection electrode ranges from 1 mm to 1.8 mm.

11. The biosensor according to one of claims claim 1, wherein the biosensor further comprises an insulating layer and a cover layer, the cover layer being provided with a vent hole, and an interlayer being disposed between the insulating layer and the cover layer.

12. The biosensor according to one of claims claim 1, wherein said fill detection electrode has the function of the counter electrode.

13. The biosensor according to claim 1, wherein said biosensor is used to detect uric acid, blood glucose, cholesterol, lipoproteins, hemoglobin, creatinine or urea in a biological sample.

14. The biosensor according to claim 2, wherein the biosensor further comprises a counter electrode.

15. The biosensor according to claim 14, wherein the fill detection electrode is further away from the sample supply port of the sample supply channel than the working electrode and the counter electrode.

16. The biosensor according to claim 15, wherein the working electrode is closest to the sample supply port, and the counter electrode is disposed between the working electrode and the fill detection electrode; or wherein the counter electrode is closest to the sample supply port, and the working electrode is disposed between the counter electrode and the fill detection electrode.

17. The biosensor according to claim 14, wherein said gap is set such that in the case where the added sample amount is the sample addition amount required by said biosensor, the working electrode and the counter electrode in the sample supply channel are already completely covered by the sample when the sample contacts the fill detection electrode.

18. The biosensor according to claim 3, wherein the biosensor further comprises a counter electrode.

19. The biosensor according to claim 18, wherein the fill detection electrode is further away from the sample supply port of the sample supply channel than the working electrode and the counter electrode.

20. The biosensor according to claim 19, wherein the working electrode is closest to the sample supply port, and the counter electrode is disposed between the working electrode and the fill detection electrode; or wherein the counter electrode is closest to the sample supply port, and the working electrode is disposed between the counter electrode and the fill detection electrode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 is a biosensor described in the present invention.

[0038] FIG. 2 is an exploded schematic diagram of the biosensor described in FIG. 1.

[0039] FIG. 3a is a schematic diagram of a biological sample added at the sample supply channel of the biosensor shown in FIG. 1 of the present invention.

[0040] FIG. 3b to FIG. 3d are situations that three different volumes of biological samples enter the sample supply channel of the biosensor shown in FIG. 1.

[0041] FIG. 4b to FIG. 4d are partial enlarged views of the sample supply channel in FIG. 3b to FIG. 3d respectively, showing how the sample in the sample supply channel covers the electrode.

[0042] FIG. 5a is a schematic diagram of a biological sample added at the sample supply channel of the biosensor shown in FIG. 7.

[0043] FIG. 5b to FIG. 5d are situations that three different volumes of biological samples enter the sample supply channel of the biosensor described in FIG. 7.

[0044] FIG. 6b to FIG. 6d are partial enlarged views of the sample supply channel in FIG. 5b to FIG. 5d respectively, showing how the sample in the sample supply channel covers the electrodes.

[0045] FIG. 7 is a biosensor with both sides of the three different volumes of biological samples electrode in contact with the inner side wall of the sample supply channel.

[0046] FIGS. 8a to 8f are biosensors of the present invention having fill detection electrodes of different shapes.

[0047] FIG. 9 is a schematic diagram of another biosensor of the present invention, which includes a working electrode and a fill detection electrode having the function of a counter electrode.

[0048] FIG. 10 is another biosensor of the present invention, with the working electrode of said biosensor being located between the counter electrode and the fill detection electrode.

[0049] FIG. 11 illustrates L1 and L2 measurement positions on the biosensor.

[0050] FIG. 12 illustrates an L3 measurement position on the biosensor.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] As shown in FIGS. 1 and 2, a biosensor of the present invention includes a working electrode 104, a counter electrode 103 and a fill detection electrode 102, which are disposed on an insulating substrate 101. The fill detection electrode 102 is further away from the sample supply port of the sample supply channel of the biosensor than the working electrode 104. The working electrode 104, the counter electrode 103 and the fill detection electrode 102 are arranged in sequence from the sample supply port 113 of the sample supply channel 112 to the distal end of the sample supply channel of the biosensor. The working electrode is closest to the sample supply port, the fill detection electrode is farthest from the sample supply port, and the counter electrode is disposed between the working electrode and the fill detection electrode. The fill detection electrode is used to determine whether the sample addition amount is sufficient, and whether the sample is sufficient refers to whether a sample added to the sensor meets the sample addition amount required by this sensor. The fill detection electrode is a linear electrode, and the ends of both sides of the line of the fill detection electrode 102 do not touch the two inner side walls 114 of the sample supply channel 112, or in other words, the positive projection of the fill detection electrode 102 on the insulating substrate does not contact or intersect with the two inner sides of the projection of the sample supply channel on the insulating substrate. As shown in FIG. 1, there's a certain spacing distance between the ends of both sides of the fill detection electrode and the two inner side walls of the sample supply channel, i.e., there is a gap 150 between the fill detection electrode and the two inner side walls of the sample supply channel, and the spacing distance or the gap is set such that: in the case where the added sample amount is the sample addition amount required by said biosensor, the working electrode and the counter electrode in the sample supply channel are already completely covered by the sample when the front edge of the sample in the sample supply channel contacts the fill detection electrode.

[0052] A way of determining the width of the fill detection electrode and the gap distance is that the width of the fill detection electrode and the spacing distance between the fill detection electrode and the inner side walls of the sample supply channel are determined according to the width of the sample supply channel and the sample addition amount. For example, as shown in FIGS. 11 and 12, FIG. 11 shows a fill detection electrode 102 in the prior art, and the fill detection electrode 102 is in contact with the inner side wall of the sample supply channel; and FIG. 12 shows a fill detection electrode 102 of the present invention, and the fill detection electrode 102 is not in contact with the inner wall of the sample supply channel. L1 refers to the width between the two inner sides of the sample supply channel. Contact point A indicates the contact point where the sample with a concave liquid surface formed contacts the fill detection electrode 102 and is closest to the sample supply port 113 when the sample in the sample supply channel covers all over the working electrode and the counter electrode. L2 is the distance from the contact point A to the inner side of the sample supply channel when the sample in the sample supply channel covers all over the working electrode and the counter electrode. The width L3 of the fill detection electrode is obtained based on L1 and L2, and the formula for calculating L3 is shown in Formula I, for example. According to Formula I, the value of L2 can be used as the gap distance between the fill detection electrode and the inner side wall of the sample supply channel.

L3=L1L2*2Formula I

[0053] Considering that the shape of the concave liquid surface of the liquid sample in the channel is not necessarily consistent after sample addition every time, for example, the concave radian of the concave liquid surface is different in size, in a preferred solution, the spacing distance from the ends of both sides of the fill detection electrode to the inner side wall of the sample supply channel is appropriately enlarged on the basis of L2 when being set, for example, L2 is selected to be multiplied by a 1.5 times enlargement factor to obtain a safe distance (the safe distance is defined as follows: regardless of the size of the concave radian of the concave liquid surface, when the tail end of the concave liquid surface of the liquid sample in the channel covers all over the working electrode and the counter electrode, none of the two sides of the concave liquid surface touches the fill detection electrode, at which time the distance from the two ends of the fill detection electrode to the inner side wall of the sample supply channel is the safe distance). Different enlargement factors can be selected according to the requirements of different biosensors. Finally, according to the width of the sample supply channel and the safe distance, the width L3 of the fill detection electrode is obtained, and the formula for calculating L3 is shown in Formula II, for example. According to Formula II, the value of said safe distance can be used as the gap distance between the fill detection electrode and the inner side wall of the sample supply channel.

L3=L1L2*1.5*2Formula II

[0054] In a specific design, when the width L1 of the sample supply channel of the biosensor of the present invention is set to range from 2.0 to 4.0 mm, the value of L2 is measured after a corresponding amount of sample is added to the sample supply channel, and its corresponding width L3 of the fill detection electrode is calculated to be in the range of about 1.0 to 1.8 mm according to Formula II, with specific values being shown in the table below.

TABLE-US-00001 Distance Safe distance L2 from from two contact ends of fill point detection Width A to electrode to L1 of inner side inner side Width L3 Sample sample of sample of sample of fill addition supply supply supply detection amount channel channel channel electrode (L) (mm) (mm) (mm) (mm) 2.4 2.0 0-0.2 0.3 1.4 2.9 2.4 0-0.2 0.3 1.8 3.7 3.0 0-0.4 0.6 1.8 4.3 3.5 0-0.8 1.2 1.1 4.9 4.0 0-1.0 1.5 1.0

[0055] Three groups of sample volumes are set as V1, V2 and V3, where V1 indicates that the sample addition amount is much less than the sample addition amount required by the biosensor; V2 indicates that the sample addition amount is more than V1, but still does not reach the sample addition amount required by the biosensor; and V3 indicates that the sample addition amount reaches the sample addition amount required by the biosensor. In the manner of FIG. 3a and FIG. 5a, different volumes of samples are added from the sample supply port to the biosensor shown in FIG. 1 and FIG. 7, respectively.

[0056] Samples of these three volumes V1, V2 and V3 are added to the sample supply channel of the biosensor shown in FIG. 1, respectively. FIGS. 3b and 4b, FIGS. 3c and 4c, and FIGS. 3d and 4d are how the electrode in the sample supply channel is covered by the sample after addition of different sample amounts, respectively. Samples of these three volumes V1, V2 and V3 are added to the sample supply channel of the biosensor shown in FIG. 7, respectively. FIGS. 5b and 6b, FIGS. 5c and 6c, and FIGS. 5d and 6d are situations that the electrode in the sample supply channel is covered after addition of different sample amounts, respectively. The structure of the biosensor shown in FIG. 7 is basically the same as that of the biosensor shown in FIG. 1, only except that the settings of the fill detection electrode of the two are different. The ends of both sides of the fill detection electrode 102 shown in FIG. 1 are not in contact with the two inner side walls of the sample supply channel, while the ends of both sides of the fill detection electrode 102 shown in FIG. 7 are in contact with the two inner side walls of the sample supply channel.

[0057] When the sample volume is V1, as shown in FIGS. 3b and 4b, and FIGS. 5b and 6b, none of the samples completely covers the counter electrode, and the sample does not contact the fill detection electrode either. In this case, the test instrument connected to the biosensor cannot detect the electrical signal of the electrical circuit associated with the fill detection electrode, and thus the test instrument gives the determination that the sample addition amount is insufficient, which is a correct determination in accordance with the actual situation. Said electrical signal of the electrical circuit associated with the fill detection electrode, is the electrical signal between the working electrode and the fill detection electrode, for example.

[0058] When the sample volume is V2, as shown in FIG. 3c and FIG. 4c, the area of the counter electrode covered by the sample is larger than the area covered when the sample addition amount is V1, but the sample still does not completely cover all over the counter electrode. Since the two ends of the fill detection electrode of the biosensor shown in FIG. 1 are not in contact with the two sides of the sample supply channel, the sample does not contact the fill detection electrode even though the front ends of both sides of the sample appearing as a concave liquid surface have reached the gap 150 (blank) area between the fill detection electrode and both sides of the sample supply channel. In this case, the test instrument does not obtain the electrical signal between the working electrode and the fill detection electrode, and gives the determination that the sample addition amount is insufficient, giving a correct determination the same as the actual sample addition situation. In contrast, as shown in FIG. 5c and FIG. 6c, the area of the counter electrode covered by the sample is larger than the area covered when the sample addition amount is V1, but the sample still does not completely cover all over the counter electrode. Since the two ends of the fill detection electrode of the biosensor shown in FIG. 7 are in contact with both sides of the sample supply channel, the front ends of both sides of the sample appearing as a concave liquid surface already reaches and contacts the fill detection electrode in the case where the sample does not completely cover all over the counter electrode. In this case, the test instrument obtains the electrical signal between the working electrode and the fill detection electrode, and gives an incorrect determination that the sample addition amount is sufficient, which is not in accordance with the actual situation.

[0059] When the sample volume is V3, as shown in FIGS. 3d and 4d, and FIGS. 5d and 6d, the sample completely covers all over the counter electrode and the working electrode, and the samples all contact the fill detection electrode. In this case, the test instrument obtains the electrical signal between the working electrode and the fill detection electrode and gives the determination that the sample addition amount is sufficient, which is a correct determination in accordance with the actual situation.

[0060] An uneven liquid front edge such as a concave liquid surface is formed at the front end of the sample in the sample supply channel of the biosensor sometimes, so the fill detection electrode set in the way of FIG. 1 can effectively reduce the probability that the test instrument incorrectly determines whether the sample addition amount is sufficient due to the occurrence of the concave liquid surface. Use of the way of designing the fill detection electrode shown in FIG. 7 is very likely to result in that the test instrument incorrectly determines whether the sample addition amount is sufficient. From the further test results in FIGS. 3b, 3c and 3d and FIGS. 5b, 5c and 5d, it can be seen that both the biosensors in FIG. 1 and FIG. 7 can determine that the sample addition amount is insufficient when the sample addition amount is very small and cannot meet the sample addition amount requirement at all; when the sample addition amount is slightly insufficient, the case of a concave liquid surface sometimes appears at the front end of the liquid surface of the sample in the sample supply channel, and in this case, the biosensor in FIG. 1 can still accurately determine that the sample addition amount is insufficient, while the biosensor in FIG. 7 will incorrectly determine that the sample addition amount is sufficient; and when the sample addition amount is sufficient, both the biosensors in FIG. 1 and FIG. 7 can determine that the sample addition amount is sufficient.

[0061] On the other hand, the fill detection electrode described in the present invention can also play a role in auxiliary positioning when the interlayer is assembled. For example, in the step of assembling the interlayer 108 when manufacturing the biosensor, as long as the inner side wall of the interlayer 108 is not in contact with the two ends of the fill detection electrode described in the present invention, it can ensure that the interlayer 108 is assembled in the correct position and the scrap rate can be reduced during production of products.

[0062] The fill detection electrode may have a - (linear) or T shape. It can also be the shapes shown in FIGS. 8a, 8b, 8c, 8d, 8e, and 8f, which are variant designs on the basis of FIG. 1, such as the convex belly shape in FIG. 8a, the oval shape in FIG. 8b, the round shape in FIG. 8c, the wavy line in FIG. 8d, the inverted T shape in FIG. 8e, and the inclined shape in FIG. 8f. The fill detection electrodes in FIGS. 8a to 8d and FIG. 8f are not in contact with the lateral side of the sample supply channel as the fill detection electrode shown in FIG. 1. The ends of both sides of the head of the fill detection electrode in FIG. 8e close to the sample supply port are not in contact with the two sides of the sample supply channel, and the tail of this electrode away from the sample supply port is in contact with both sides of the sample supply channel. The two ends of the fill detection electrode have a certain distance from both sides of the sample supply channel, and the distance meets the condition that the working electrode and/or the counter electrode is already covered by the sample when the sample contacts the fill detection electrode in the case where the added sample reaches the sample addition amount required by the biosensor.

[0063] In a preferred example, the fill detection electrode as shown in FIG. 1 is designed in a T shape, and for the fill detection electrode, the end 1021 of I of the T shape is connected to a wire 105. Such design can not only avoid the impact of overprinting deviation during the production of test strips when the design of the fill detection electrode is designed too narrow, but also reduce the production cost.

[0064] The working electrode, the counter electrode, and the fill detection electrode may also be referred to as an electrode system, and the biosensor 100 shown in FIGS. 1 and 2 further includes an insulating layer 106 disposed on the electrode system. A reagent layer 107 covers at least the working electrode. An interlayer 108 is disposed between the insulating layer 106 and a cover layer 110, and grooves 109 and 106 are formed at positions at the front ends of the interlayer and the insulating layer corresponding to the electrode system, respectively, and said grooves together with the cover layer 110 and the insulating substrate 101 form the sample supply channel 112, in which the working electrode, the counter electrode and the fill detection electrode are exposed. The cover layer is provided with a vent hole 111, and when the sample enters through the sample supply port of the sample supply channel, the gas in the sample supply channel is discharged through the vent hole, so that the detection sample automatically enters the sample supply channel by capillary-siphon action. One end of the wire 105 on the insulating substrate 101 is connected to the electrode, and the other end of the wire 105 is connected to the contact pin in the test instrument. The wire 105 has the function of powering on the instrument and identifying a test strip.

[0065] The material of the insulating substrate 101 can be polystyrene, polycarbonate, polyvinyl chloride resin and polyester and other substances. The insulating substrate provides support for the electrodes and electrode wires.

[0066] The electrodes and the wires can be disposed on the insulating substrate by screen printing or laser engraving, etc. They can use silver or silver chloride, carbon, graphite, palladium, gold, platinum, iridium stainless steel and other suitable conductive materials. The electrodes can also be made from a combination of these materials. For example, the electrodes are made of graphite material and the wires are made of silver material. Said electrode system is a three-electrode system, or may be a two-electrode system, wherein one is the working electrode, and one is the counter electrode, which may also act as the fill detection electrode. The material of the counter electrode can be Ag/AgCl and other materials, but is not limited to these materials. The biosensor as shown in FIG. 9 includes a working electrode 104 and a fill detection electrode 102, and said fill detection electrode also has the function of the counter electrode. A certain spacing distance between the ends of both sides of the fill detection electrode and the two inner side walls of the sample supply channel meets that: in the case where the added sample amount is the sample addition amount required by said biosensor, the working electrode in the sample supply channel is already completely covered by the sample when the sample in the sample supply channel contacts the fill detection electrode.

[0067] In some other design solutions, the order of the working electrode and the counter electrode of the biosensor described in the present invention is interchangeable. If the working electrode 104 and counter electrode 103 are interchanged in the present invention, the biosensor shown in FIG. 10, for example, includes the working electrode 104, the counter electrode 103 and the fill detection electrode 102, the counter electrode is closest to the sample supply port, the fill detection electrode is farthest from the sample supply port, and the working electrode is disposed between the counter electrode and the fill detection electrode.

[0068] The material of the interlayer 108 can be a hydrophilic binder material, which can be an adhesive tape with or without a substrate, and then bonded after processing; or it can be a glue or polymer slurry, which is printed by screen printing.

[0069] The insulating layer 106 is made of an insulating material. In the biosensor, the insulating layer 106 is a non-essential element, and in some designs, the biosensor may not include an insulating layer. If the electrodes are not separated by an insulating layer, the material of the interlayer adopts an insulating material.

[0070] The inner side of the groove 109 of the interlayer 108 forming the sample supply channel is made of a hydrophilic material or treated with a hydrophilic material, and the side of the cover layer 110 facing the sample supply channel is made of a hydrophilic material or treated with a hydrophilic material. When a blood sample flows in this sample supply channel, the sample solution diffuses faster than the middle sample at the contact end of the hydrophilic lateral side of the sample supply channel, sometimes resulting in the formation of a concave liquid surface at the front edge of the sample. When the sample with a concave liquid surface formed diffuses along the sample supply channel, the liquid surface at the two ends of the front edge of the sample contacts the extended line of the fill detection electrode earlier than the liquid surface in the middle of the sample.

[0071] In one design solution, the reagent layer 107 is added to the working electrode, but it can also be added to the counter electrode at the same time, with no reagent layer covering the fill detection electrode. The reagent layer contains one or more chemical components used to detect the presence or absence of an analyte or its content in the liquid sample. For example, the reagent layer includes an oxidoreductase and an electron acceptor, both of which are used to detect the sample and produce a reaction product measurable by an electronic detection system. A specific embodiment is that the target analyte detected by the biosensor is uric acid in blood. The reaction reagent layer includes chemical reagents such as buffer solutions, polymers, and mediators. The reagents may also include a binder. The binder is hydroxyethylcellulose (HEC), which is hydrophilic and can be used to mix with an introduced blood sample, allowing establishment of an electrochemical cell within a few seconds. Other materials can also be used as the binder, such as hydroxymethyl cellulose and hydroxypropyl cellulose. The reaction reagent layer may also include a stabilizer. The reaction layer may also contain mediators, surfactants, polymers, and other reagents that are conducive to carrying out the detection.

[0072] The present invention is designed to be a biosensor for detecting blood glucose, uric acid, hemoglobin (Hb), cholesterol, lipoproteins, creatinine, or urea or the like in biological samples.

[0073] The cover layer 110 can be made of a PET material, preferably a transparent hydrophilic material. The transparent window can better reflect the state of the sample entering the sample supply channel, and the hydrophilic material can lead to smoother sample supply.

[0074] The test instrument is provided therein with contact pins in electrical contact with different wires of the biosensor, and the electrical circuit is formed among the contact pins, wires and at least two different electrodes, and the test instrument measures the electrical signal of the electrical circuit.

[0075] The fill detection electrode described in the present invention is used to determine whether the sample added to the biosensor is sufficient and whether the sample reaches the sample addition amount required by the biosensor, according to whether the test instrument can detect whether an electrical signal is generated between the fill detection electrode and another electrode paired with this electrode, or whether this generated electrical signal is greater than a set value which is preset. When the generated electrical signal is greater than the set value, the instrument determines that the added sample amount is sufficient. When no electrical signal is generated or the electrical signal is greater or less than the set value, the instrument determines that the added sample amount is insufficient.

[0076] A method for analyzing an analyte in a sample by a biosensor described in the present invention, comprises the following steps: [0077] Step 1: the biosensor is inserted into a test instrument, and the test instrument is triggered to power on after the wires of the biosensor contact the contact pins inside the instrument. [0078] Step 2: the test instrument enters the self-test process. [0079] Step 3: after the instrument displays a sample addition identifier, the operator is prompted to add the sample to the biosensor. [0080] Step 4: the operator adds the sample to the sample supply port of the biosensor and starts a sample addition test. [0081] Step 5: the test instrument applies a DC (direct current) voltage or an AC (alternating current) voltage with small amplitude between the working electrode and the counter electrode to obtain a current signal 1. [0082] Step 6: the working electrode and the counter electrode are disconnected, and the test instrument applies a DC (direct current) voltage or an AC (alternating current) voltage with small amplitude between the working electrode and the fill detection electrode, and circle detection is performed within a specified time to obtain a current signal 2.

[0083] If the obtained current signal 2 is greater than the set value within the specified time, the test instrument determines that the sample addition amount is sufficient.

[0084] If no current signal 2 greater than the set value is obtained within the specified time, the test instrument determines that the sample addition amount is insufficient.

[0085] Said specified time is within 0 to 5 s.

[0086] Step 7: if the sample addition amount is sufficient, the test instrument obtains the test result of the analyte according to the current signal 1. If the sample addition amount is insufficient, the test instrument gives a message that the sample addition amount is insufficient, and the detection ends.

[0087] Steps 1 to 3 are non-essential steps, and they can be set or not set by the test instrument according to actual situations. Steps 5 and 6 are interchangeable, i.e., step 5 is operated after step 6. In step 5, if the fill detection electrode of the electrode system of the biosensor serves the function of determining whether the sample addition amount is sufficient when determining whether the sample addition amount is sufficient, and serves the function of the counter electrode when measuring the analyte in the sample. The counter electrode in step 5 is replaced with the fill detection electrode.

[0088] The set value used for determination can be predetermined by experimental testing.

Example 1 Experiment on Error Reporting Accuracy of Biosensor for Insufficient Sample Addition Amount

[0089] A biosensor for measuring the content of uric acid in blood, used the structure of the biosensor shown in FIGS. 1 and 2. The fill detection electrode was not in contact with both sides of the sample supply channel, the length of the working electrode was 3.2 mm, the length of the counter electrode was 2.2 mm, the fill detection electrode had a width (L3) of 1.6 mm and a length of 0.6 mm, the width of the sample supply channel was 2.3 mm, the spacing distance between the two ends of the fill detection electrode and the inner side of the sample supply channel was 0.35 mm, and the spacing distance between the counter electrode and the fill detection electrode was 0.65 mm. The reagents on the working electrode and counter electrode included buffer solutions, polymers, mediators and other reagents. The test instrument applied a 0.4V DC voltage between the working electrode and the fill detection electrode, and a current signal 2 was obtained from the fill detection electrode and the working electrode, with the circle test time being 1 second. (The length described in the present invention was the distance in a direction the same as the sample flow direction, and the width was the distance in a direction perpendicular to the sample flow direction. Said sample flow referred to the flow of the sample over the electrodes.)

[0090] Different volumes of sample with different hematocrit and different concentrations of a substance to be tested were added to the biosensor shown in FIG. 1 and the biosensor shown in FIG. 7, respectively. The fill detection electrode of the biosensor shown in FIG. 1 was not in contact with both sides of the sample supply channel, and the fill detection electrode of the biosensor shown in FIG. 7 was in contact with both sides of the sample supply channel. 30 samples were tested under each test condition, and error reporting times and the accuracy were calculated respectively. In this experiment, the sample volumes were V1, V2 and V3, where V1 was 2.4 L, V2 was 2.7 L and V3 was 3.0 L, and different volumes of samples were added to the above two biosensors, respectively. When the sample volume was V1, the sample did not completely cover the counter electrode; when the sample volume was V2, the sample basically covered the counter electrode, but did not completely cover the counter electrode; and when the sample volume was V3, the sample completely covered the electrode system, V3 being the sample addition amount required by this biosensor. Blood samples with 10%, 42% and 70% hematocrit were prepared as the samples to be tested. The sample statuses in the sample supply channel were shown in FIGS. 4 and 6.

[0091] Blood samples with different hematocrit were added, and the experimental results about sample supply were shown in Table 2 and Table 3, respectively. The experimental results indicated that (1) when the sample volume was V1, both the biosensor in FIG. 1 and the biosensor in FIG. 7 would obtain an accurate message that the sample addition amount was insufficient because the solution did not reach the third electrode. (2) When the sample volume was V2, in the test of the biosensor in FIG. 7, because the front end of the sample with a concave liquid surface formed would contact the fill detection electrode in contact with the sample supply channel, the two ends of the solution would diffuse along the hydrophilic interlayer when the sample was added, and the diffusion speed at the two ends was faster than that in the middle, the solution in the sample supply channel reached the fill detection electrode at first and generated a current, so that the instrument did not obtain the message that the sample addition amount was insufficient, but the sample supply channel was not filled with the sample actually; while in the test of the biosensor in FIG. 1, even though a concave liquid surface was formed at the front end of the sample, the biosensor in FIG. 1 still obtained the accurate message that the sample addition amount was insufficient in each test because the sample did not touch the fill detection electrode not in contact with the sample supply channel. (3) When the sample volume was V3, the biosensors in FIG. 1 and FIG. 7 both obtained a message that the sample addition amount was sufficient because the solution already covered the electrode system.

[0092] The fill detection electrode designed by the present invention could accurately determine whether the sample addition amount is sufficient, which was not affected by the hematocrit of the sample.

TABLE-US-00002 TABLE 2 Experiment on sample addition amount over electrode shown in FIG. 1 Hematocrit 10% 10% 10% 42% 42% 42% 70% 70% 70% Concentration 250 250 250 250 250 250 250 250 250 of substance to be tested (mol/L) Sample volume V1 V2 V3 V1 V2 V3 V1 V2 V3 (l) Number of tests 30 30 30 30 30 30 30 30 30 Error reporting 30 30 0 30 30 0 30 30 0 times Accuracy rate 100% 100% 100% 100% 100% 100% 100% 100% 100% Hematocrit 10% 10% 10% 42% 42% 42% 70% 70% 70% Concentration 600 600 600 600 600 600 600 600 600 of substance to be tested (mol/L) Sample volume V1 V2 V3 V1 V2 V3 V1 V2 V3 (l) Number of tests 30 30 30 30 30 30 30 30 30 Error reporting 30 30 0 30 30 0 30 30 0 times Accuracy rate 100% 100% 100% 100% 100% 100% 100% 100% 100% Hematocrit 10% 10% 10% 42% 42% 42% 70% 70% 70% Concentration 1100 1100 1100 1100 1100 1100 1100 1100 1100 of substance to be tested (mol/L) Sample volume V1 V2 V3 V1 V2 V3 V1 V2 V3 (l) Number of tests 30 30 30 30 30 30 30 30 30 Error reporting 30 30 0 30 30 0 30 30 0 times Accuracy rate 100% 100% 100% 100% 100% 100% 100% 100% 100% Total number 90 90 90 90 90 90 90 90 90 of tests Total error 90 90 0 90 90 0 90 90 0 reporting times Total accuracy 100% 100% 100% 100% 100% 100% 100% 100% 100% rate

TABLE-US-00003 TABLE 3 Experiment on sample addition amount over electrode shown in FIG. 7 Hematocrit 10% 10% 10% 42% 42% 42% 70% 70% 70% Concentration 250 250 250 250 250 250 250 250 250 of substance to be tested (umol/L) Sample volume V1 V2 V3 V1 V2 V3 V1 V2 V3 (pl) Number of tests 30 30 30 30 30 30 30 30 30 Error reporting times 30 0 0 30 0 0 30 0 0 Accuracy rate 100% 0% 100% 100% 0% 100% 100% 0% 100% Hematocrit 10% 10% 10% 10% 10% 10% 10% 10% 10% Concentration 600 600 600 600 600 600 600 600 600 of substance to be tested (mol/L) Sample volume V1 V2 V3 V1 V2 V3 V1 V2 V3 (l) Number of tests 30 30 30 30 30 30 30 30 30 Error reporting times 30 0 0 30 0 0 30 0 0 Accuracy rate 100% 0% 100% 100% 0% 100% 100% 0% 100% Hematocrit 10% 10% 10% 42% 42% 42% 70% 70% 70% Concentration of substance to be tested 1100 1100 1100 1100 1100 1100 1100 1100 1100 (mol/L) Sample volume V1 V2 V3 V1 V2 V3 V1 V2 V3 (l) Number of tests 30 30 30 30 30 30 30 30 30 Error reporting 30 0 0 30 0 0 30 0 0 times Accuracy rate 100% 0% 100% 100% 0% 100% 100% 0% 100% Total number 90 90 90 90 90 90 90 90 90 of tests Total error 90 0 0 90 0 0 90 0 0 reporting times Total accuracy 100% 0% 100% 100% 0% 100% 100% 0% 100% rate (Note: This experiment counts the number of errors reporting times by the sample volume V2, which were merely conditions of FIGS. 3c and 4c and FIGS. 5c and 6c formed in the sample supply channel after sample addition)

Example 2 Experiment on Sample Addition Amounts at Different Temperatures

[0093] Temperature also has a relatively significant effect on the rate of the sample entering the sample supply channel. Therefore, in this example, on the basis of Example 1, the biosensor in FIG. 1 and the biosensor in FIG. 7 were tested at different temperatures (2.5 C., 10.0 C., 21.0 C., 40.0 C., and 47.5 C.), samples with different hematocrit (10%, 42%, and 70%) were added to the sample supply channel of a test strip in a sample addition amount V2, i.e., 2.7 L, and 100 times of tests were carried out under each test condition.

[0094] The experimental results were shown in Table 4 and Table 5 below. The experiments showed that the test accuracy of the biosensor in FIG. 1 was significantly higher than that of the biosensor in FIG. 7 at different temperatures. Even at different temperatures, the fill detection electrode not in contact with the sample supply channel also could greatly avoid the risk that the instrument made an incorrect determination due to insufficient sample amount.

TABLE-US-00004 TABLE 4 Experiment on sample addition amount over electrode shown in FIG. 1 Hematocrit 10% 10% 10% 10% 10% 42% 42% 42% 42% 42% 70% 70% 70% 70% 70% Concentration of substance to 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 be tested (mol/L) Temperature 2.5 10.0 21.0 40.0 147.5 2.5 10.0 21.0 40.0 47.5 2.5 10.0 21.0 40.0 47.5 of test environment ( C.) Sample V2 V2 V2 V2 V2 V2 V2 V2 V2 V2 V2 V2 V2 V2 V2 volume (l) Number of 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 tests Error 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 reporting times Accuracy 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% rate

TABLE-US-00005 TABLE 5 Experiment on sample addition amount over electrode shown in FIG. 7 Hematocrit 10% 10% 10%| 10% 10% 42% 42% 42% 42% 42% 70% 70% 70% 70% 70% Concentration 200 200 200 200 200 200 200 200 200 200 200 200 200 200 200 of substance to be tested (mol/L) Temperature 2.5 10.0 21.0 40.0 47.5 2.5 10.0 21.0 40.0 47.5 2.5 10.0 21.0 40.0 47.5 of test environment ( C.) Sample V2 V2 V2 V2 V2 V2 V2 V2 V2 V2 V2 V2 V2 V2 V2 volume (l) Number of 100 1100 100 100 100 100 100 100 100 100 100 100 100 100 100 tests Error 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 reporting times Accuracy rate 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% 0% (Note: This experiment counts the number of errors reporting times by the sample volume V2, which were merely conditions of FIGS 3c and 4c and FIGS. 5c and 6c formed in the sample supply channel after sample addition)

Example 3 Experiment on Test Accuracy

[0095] The biosensor shown in FIG. 1 was used to carry out the experiment on test accuracy.

[0096] Blood samples, the uric acid concentrations of which were 250 mol/L, 500 mol/L, 700 mol/L and 1050 mol/L respectively, were added to the biosensor shown in FIG. 1 of the present invention at ambient temperatures 7.5 C., 21 C. and 42.5 C. for detection, and the sample addition amount was 3.0 l as required by this test strip, with the results shown in Table 6 below. The experiment indicated that the biosensor of the present invention had a small deviation from Mindray BS-350E fully automated biochemical test instrument in various concentration segments of uric acid tests, and has good test stability.

TABLE-US-00006 TABLE 6 Experiment on test accuracy of urine acid Test value- 232 523 706 1068 232 523 706 1068 232 523 706 1068 1 of biochemical analyzer (mol/L) Test value- 236 519 705 1057 236 519 705 1057 236 519 705 1057 2 of biochemical analyzer (mol/L) Average test 234.0 521.0 705.5 1062.5 234.0 521.0 705.5 1062.5 234.0 521.0 705.5 1062.5 value of biochemical analyzer (mol/L) Temperature 7.5 C. 7.5 C. 7.5 C. 7.5 C. 21 C. 21C 21 C. 21 C. 42.5 C. 42.5 C. 42.5 C. 42.5 C. of test environment Reading of test instrument (mol/L) Test value 1 222 481 718 1037 229 515 711 1057 213 510 758 1087 Test value 2 246 490 702 1028 265 494 717 1074 238 516 754 1097 Test value 3 226 489 706 1057 223 494 698 1045 223 558 774 1100 Test value 4 210 484 696 1000 233 516 719 1029 187 556 732 1082 Test value 5 222 511 682 1006 234 509 698 1048 217 504 749 1080 Test value 6 246 499 709 1028 246 513 712 1046 219 498 752 1095 Test value 7 229 502 708 1006 233 519 693 1006 226 561 741 1054 Test value 8 221 488 729 1027 230 500 682 1017 210 520 753 1041 Test value 9 202 508 695 1025 215 495 705 1018 184 545 740 1050 Test value 10 218 498 686 1023 194 489 696 1040 192 525 741 1056 Test value 11 201 482 706 1017 221 526 708 1034 198 520 733 1077 Test value 12 220 489 727 1014 223 493 699 1041 234 531 736 1055 Test value 13 211 507 705 1004 218 485 691 1037 227 525 732 1036 Test value 14 226 491 721 999 232 519 701 1028 197 492 742 1068 Test value 15 200 502 720 1005 222 521 726 1039 216 520 747 1059 Test value 16 218 504 671 1012 237 478 697 1030 168 528 743 1067 Test value 17 224 502 694 1023 272 488 717 1010 195 490 746 1067 Test value 18 218 515 711 992 223 497 685 1021 215 509 744 1104 Test value 19 235 512 715 1042 206 499 714 1033 218 509 740 1050 Test value 20 225 510 725 1027 222 503 681 1016 211 525 728 1096 Average test 221.0 498.2 706.3 1018.6 228.9 502.7 702.5 1033.5 209.4 522.1 744.3 1071.1 value SD 12.64 10.71 15.55 16.19 17.63 13.70 12.80 16.51 18.01 20.52 10.67 20.85 CV 5.7% 2.1% 2.2% 1.6% 7.7% 2.7% 1.8% 1.6% 8.6% 3.9% 1.4% 1.9% Deviation 13.0 4.4% 0.1% 4.1% 5.1 3.5% 0.4% 2.7% 24.6 0.2% 5.5% 0.8% from test value of biochemical analyzer (%)