Biosensor and preparation method thereof

Abstract

The invention provides a biosensor and a preparation method thereof, and the biosensor comprises an insulating substrate, a sample injection port, a sample injection channel for a detection sample to enter, a conductive layer arranged on the insulating substrate, engraving lines distributed on the conductive layer, and electrodes divided by the engraving lines, a reagent layer is arranged on a part of or all of the electrodes in the sampling channel area, and a short circuit prevention area is arranged at the edge of the biosensor. According to the invention, the risk of short circuit between the electrodes of the biosensor can be effectively overcome.

Description

Technical Field

[0001] The present invention relates to the field of biomedical detection, and particularly to a biosensor and a method. Background Art

[0002] Electrochemical sensors for detecting the content of analytes in samples and their supporting detectors have been widely used in the daily monitoring of diseases. For example, diabetic patients usually use electrochemical sensors to monitor the glucose concentration in their daily blood.

[0003] The basic structure of such electrochemical sensors includes: an electrode system disposed on an insulating substrate, the electrode system including a working electrode, a counter electrode, and multiple or various types of electrodes, and a reaction reagent that reacts with the analyte covering the corresponding electrode. A sample spacer with a groove is located on the electrode, and a cover sheet with air holes covers the sample spacer. The insulating substrate, the spacer, and the cover sheet form an injection channel, and the other end of the electrode system is in contact with the contacts of the detector. The sample flowing into the injection channel reacts with the reaction reagent on the electrode to generate an electrical signal, and the detector obtains the detection result based on these electrical signals.

[0004] Using screen printing technology to print conductive materials on an insulating substrate to form electrodes, electrode connection contacts, and leads is a commonly used method for preparing electrochemical sensors. When manufacturing electrochemical sensors using the screen printing method, there are significant batch-to-batch differences in some parameters for each batch. To eliminate the influence of batch-to-batch differences on the detection results, generally, a calibration chip is inserted into the detector to correct the detection results, thereby overcoming the problem of batch-to-batch differences. However, inserting a calibration chip not only increases the operation steps of the operator, but also if the operator forgets to insert or inserts the calibration chip incorrectly, it will lead to inaccurate detection results. Some researchers have also adopted methods such as those in Chinese Patent ZL201210095096.5 to correct batch-to-batch differences, by setting calibration information on the sensor.

[0005] To solve the problems of cumbersome detection steps or complex preparation processes mentioned above, Chinese Patent ZL00803756.6 provides a method for forming a thin film electrode, that is, a thin film-shaped conductor layer is uniformly paved on an insulating substrate in advance, and the electrode is formed by laser etching. This method has a high manufacturing precision and can basically ensure that there are no batch-to-batch differences between products produced in different batches, or the existence of batch-to-batch differences will not affect the detection results without correction.

[0006] The process of evenly covering the thin-film conductive layer on the insulating substrate determines the adhesion between the conductive layer and the insulating substrate. Different processes, different conductive layers, and insulating substrates made of different materials are all factors affecting the adhesion. The quality of the adhesion between the conductive layer and the insulating substrate directly affects the cutting performance of the sensor. During the process of using a cutting tool to cut the semi-finished thin-film sensor into individual finished sensors, metal conductive layers such as gold, palladium, etc., or non-metal conductive layers such as carbon, conductive glass, etc., will produce metal conductive particles or non-metal conductive particles due to the difference in adhesion and the mechanical shear force of the cutting process on the conductive layer, and may remain in the engraved lines near the travel route of the cutting tool, thus connecting multiple electrode regions that should originally be open circuits to form a short circuit. The resulting finished sensor can only be scrapped.

[0007] A biosensor includes an insulating substrate and a conductive layer disposed on the insulating substrate. Engraved lines are distributed on the conductive layer, and electrodes are formed on the conductive layer and separated by the engraved lines. The detection reagent is added to all or part of the electrodes at the sample contact end. The biosensor also includes a fluid channel for the solution of the analyte to enter, and the fluid channel is jointly composed of the conductive layer, the opening groove of the middle partition layer, and the upper cover. The electrodes extend from the sample contact end to the sensor contact end, and conduct the electrical signal generated by the reaction between the analyte and the reagent to the sensor contact end, and then the test result is reported to the user through the instrument. After the cutting process of the sensor is completed, quality inspection personnel will detect the sensor to determine whether the obtained sensor is qualified. Among them, detecting whether the sensor will cause a short circuit between the electrodes due to cutting and thus be scrapped is a particularly important step.

[0008] Specifically, during the process of cutting the semi-finished biosensor into independent finished biosensors, there is mechanical shear on the conductive layer along the travel route of the cutting tool. After the conductive layer is stressed, there is a certain probability that conductive particles will flake off or detach and remain in the nearby engraved lines. As Figure 1 shown, it is a schematic diagram of the conductive layer of a thin-film electrode biosensor, where 21, 22, 23, 24 are the edges of the conductive layer obtained after the cutting tool cuts along the preset route, and the travel route of the cutting tool intersects with the engraved lines 31, 32, 33, 34, 41, 43. Figure 1 at L of Figure 1The magnified views of the regions selected for the instrument contact end and the sample contact end of the illustrated sensor are shown at R. The electrodes D and E on the left and right sides of the engraving line 34 are separated by the engraving line 34, and the electrodes D and E should be open circuits with respect to each other, and there is no electrical conduction between them. When the cutting tool cuts along the preset route to obtain the bio-sensor side line 24, when the cutting tool reaches the engraving line 34, due to the conductive layer being subjected to a certain mechanical shearing force, conductive particles X may flake off or detach and remain in the engraving line 34, resulting in electrical conduction between the electrodes D and E through the conductive particles X, that is, a short circuit occurs between the electrodes D and E. When the sensor with this phenomenon is inserted into the detection instrument, if the detection instrument detects a short circuit between the electrodes, it will automatically report an error and the user cannot use it. Similarly, when the cutting tool cuts along the preset route to obtain the bio-sensor side line 21, when the cutting tool reaches the engraving line 41, it is also possible that the peeled conductive particles X remain in the engraving line 41, resulting in electrical conduction between the electrode B and the non-electrode conductive block region A other than the electrode B. The non-electrode conductive block region A does not participate in the conduction of electrochemical signals. The electrode B is connected to the electrode C at the instrument contact end, and the two together form an electrode participating in the conduction of electrochemical signals. Since a short circuit occurs between the non-electrode conductive block region A and the electrode B, the size of the sensor electrode B changes, that is, the electrode size of the electrode B also includes the non-electrode conductive block region A with which it has a short circuit, which may cause fluctuations in the conduction signal and lead to deviations in the measured values of the sensor. In Figure 1 In the attached drawing indication, the electrodes B and C point to the same electrode, and the electrodes B and C are the same electrode.

[0009] Sensors in which short circuits occur between electrodes that were originally disconnected due to conductive particles remaining in the engraving line, or sensors in which the electrode size fluctuates due to conductive particles remaining on the common engraving line, are all defective waste products that cannot be used by customers. Since the size of the conductive particles is small, it is impossible to quickly judge by the naked eye. Summary of the Invention

[0010] The present invention is completed based on the above problems existing in the prior art, and its purpose is to provide a bio-sensor that can avoid the risk of short circuits between electrodes or between an electrode and a non-electrode conductive block region other than the electrode.

[0011] The short-circuit prevention area is jointly composed of the engraving line and the bio-sensor side line, and its main purpose is to avoid the risk of sensor scrapping caused by electrical conduction between electrodes or between an electrode and a non-electrode conductive block region other than the electrode. The short-circuit prevention area is provided at the four peripheral edges of the sensor or is relatively close to the bio-sensor side line.

[0012] Since the laser etching process has a large customization space, technicians can design the travel route of the engraving line according to the actual situation or customize the etching parameters of the engraving line. Therefore, the design scheme of the short-circuit prevention area has various forms. Specifically, the short-circuit prevention area can be enclosed by multiple independent engraving lines and the conductive layer side line. The above solutions can well avoid the risk that the non-electrode conductive block areas on both sides of the engraving line on the edge of the biosensor are connected by residual conductive particles, and have strong operability and practicability. The above solutions will be specifically described below in combination with specific embodiments.

[0013] Therefore, the present invention provides a biosensor, comprising an insulating substrate, a sample inlet, a sample inlet channel for detecting samples to enter, a conductive layer provided on the insulating substrate, engraving lines distributed on the conductive layer, and electrodes formed by dividing the engraving lines. A reagent layer is provided on some or all of the electrodes located in the sample inlet channel area. On the path where two adjacent electrodes extend towards the edge of the biosensor, at least one electrode does not extend to the edge of the biosensor; or on the path where the electrode and the non-electrode conductive block adjacent to it extend towards the edge of the biosensor, at least one of the electrode or the non-electrode conductive block does not extend to the edge of the biosensor.

[0014] Furthermore, between two adjacent electrodes, at least one of the electrodes and the sensor edge is provided with a non-electrode conductive block.

[0015] Furthermore, a short-circuit prevention area is provided between the electrode that does not extend to the edge of the biosensor or the conductive block that does not extend to the edge of the biosensor and the edge of the biosensor.

[0016] Furthermore, the short-circuit prevention area is enclosed by the conductive layer side line and the engraving line.

[0017] Furthermore, neither of the adjacent electrodes extends to the edge of the biosensor, or neither the adjacent electrode nor the non-electrode conductive block extends to the edge of the biosensor.

[0018] Furthermore, the engraving lines on the conductive layer do not intersect with the biosensor side line.

[0019] Furthermore, the conductive layer is selected from gold, silver, platinum, palladium, carbon, graphite, conductive glass, or a mixture thereof.

[0020] The present invention also provides a method for preparing a biosensor, comprising the following steps: on a raw material having an insulating substrate and a conductive layer, engraving lines are etched on the conductive layer, and electrodes are formed by dividing with the engraving lines; the prepared reagent is added to the corresponding electrodes; a middle spacer layer and an upper cover are sequentially pasted on the electrodes to form a biosensor with a sample injection channel; on the path where two adjacent electrodes extend towards the edge of the biosensor, at least one electrode does not extend to the edge of the biosensor; or on the path where an electrode and a non-electrode conductive block adjacent thereto extend towards the edge of the biosensor, at least one of the electrode or the non-electrode conductive block does not extend to the edge of the biosensor; or between two adjacent electrodes, at least one of the electrodes is provided with a non-electrode conductive block between it and the sensor edge.

[0021] Further, the conductive layer is selected from gold, silver, platinum, palladium, carbon, graphite, conductive glass, or a mixture thereof.

[0022] Further, the etching method is laser cutting or laser marking.

[0023] The present invention also provides a method for avoiding short circuit of the electrodes of a biosensor. On the path where two adjacent electrodes extend towards the edge of the biosensor, at least one electrode does not extend to the edge of the biosensor; or on the path where an electrode and a non-electrode conductive block adjacent thereto extend towards the edge of the biosensor, at least one of the electrode or the non-electrode conductive block does not extend to the edge of the biosensor; or between two adjacent electrodes, at least one of the electrodes is provided with a non-electrode conductive block between it and the sensor edge.

[0024] The present invention proposes a scheme for setting up a short-circuit prevention area on a conductive layer through the controllable design of engraving lines, which can effectively avoid the risk of the non-electrode conductive block areas on both sides of the engraving lines being conducted by residual conductive particles, so as to ensure the stable performance of the finished sensor and improve the finished product yield of the sensor. Description of the Drawings

[0025] Figure 1 is a schematic diagram of the electrode and engraving line distribution of the electrode biosensor conductive layer without a short-circuit prevention area.

[0026] Figure 2 is an exploded schematic diagram of the biosensor of the present invention.

[0027] Figure 3 is a flowchart of the manufacturing method of the biosensor

[0028] Figure 4 is a schematic diagram of the sensor basic unit A arranged in multiple rows formed by laser engraving of the biosensor conductive layer.

[0029] Figure 5 is along the cutting knife Figure 4Schematic diagram of the sensor basic unit A arranged in a single row formed after cutting along the cutting line 50 shown.

[0030] Figure 6 It is a schematic diagram of the design of the short - circuit prevention area in Embodiment 1. Among them, R and L are enlarged views of the left figure.

[0031] Figure 6-1 They are schematic diagrams of two other designs of the short - circuit prevention area in Embodiment 1.

[0032] Figure 6-2 It is another schematic diagram of the short - circuit prevention design. Among them, R and L are enlarged views of the left figure.

[0033] Figure 7 It is a line graph of the test values of the glucose sensor in Embodiment 3 and the test values of YSI. Detailed implementation manners

[0034] Hereinafter, the implementation manners of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments listed.

[0035] Embodiment 1:

[0036] As Figure 2 and Figure 6 shown, the biosensor 100 includes an insulating substrate 1, an electrode system formed on the substrate by dividing a conductive layer 2 through engraved lines. The electrode system includes a working electrode E, a counter electrode D, and a reference electrode C. The electrodes have a sample contact end 101 in contact with the sample and a contact end 102 in contact with the analyzer contacts. A reagent layer 6 is added to the corresponding electrodes at the sample contact end. A septum layer 8 with an opening groove 81 covers the sample contact end of the electrodes. An upper cover 9 covers the septum layer 8. Thus, a sample injection channel is formed between the conductive layer 2, the opening groove 81, and the upper cover 9. Electrodes and a reagent layer are provided in the sample injection channel. An air vent 91 is opened on the upper cover 9, and the air vent is located above the opening groove for discharging the gas in the sample injection channel after sample addition.

[0037] Engraved lines are distributed on the conductive layer 2 and are divided into independent conductive blocks through the engraved lines. These independent conductive blocks can be divided into electrode and non - electrode conductive blocks. The so - called electrode refers to a conductive block with part located in the sample injection channel and the remaining part extending towards the contact end of the biosensor, such as electrodes C, D, and E. Non - electrode conductive blocks refer to conductive blocks other than electrodes, such as conductive blocks A, A1, B1, C1, D1, E1, and the area enclosed by the engraved lines 41, 31, 42, and the side lines, etc. In Figure 2 , Figure 6-1 and Figure 6-2 the attached drawings, electrode B and electrode C point to the same electrode, and electrode B and electrode C are the same electrode.

[0038] The electrode is formed after the conductive layer 2 is divided by engraved lines. The engraved lines are insulating gaps left after removing the conductive material, and the engraved lines are not limited to the gaps formed by engraving. Figure 2 The front view of the corresponding conductive layer 2 is as Figure 6 shown. The working electrode E is enclosed by engraved lines 32, 33, 34, 42, 43, 44. The counter electrode D is enclosed by engraved lines 33, 34, 42, 44, 45. The reference electrode C is enclosed by engraved lines 31, 32, 33, 41, 42, 43.

[0039] The engraved lines in the present invention are not only limited to straight lines, but can also be curves such as arcs and wavy lines. The transverse engraved lines do not mean that they need to be parallel to the two end edges of the sample end and the contact end of the biosensor. The transverse engraved lines can be parallel to the end edges or at a certain angle to the end edges. The longitudinal engraved lines do not mean that they need to be parallel to the two side edges of the biosensor. The longitudinal engraved lines can be parallel to the side edges or at a certain angle to the side edges.

[0040] Taking Figure 3 、 Figure 4 and Figure 5 as examples to illustrate a method for manufacturing the Figure 2 shown biosensor.

[0041] Step 1: Laser etching of the electrode pattern: According to the pre-designed electrode pattern, on the raw material with an insulating substrate and a conductive layer, use a laser to etch the electrode pattern on the conductive layer to obtain the electrode large cards of multiple sensor basic units A.

[0042] Step 2: Adding a reagent layer: Prepare the detection reagent and add the prepared reagent to the corresponding electrodes that need to add the reagent.

[0043] Step 3: Attach the septum 8 to each sensor basic unit A. Generally, the septum is placed at the sample contact end of the biosensor.

[0044] Step 4: Paste the upper cover 9 on each septum 8 and roll it.

[0045] Step 5: After the upper cover is attached, attach and roll the color layer on the upper cover to obtain a semi-finished large card.

[0046] Step 6: Cutting: Use a cutting tool to cut the semi-finished large card along the preset cutting line to obtain the finished biosensor.

[0047] Specifically, in step 1, a laser etching technique is used to etch the conductive layer 2 on the surface of the insulating substrate, forming multiple engraving lines 31 - 34 and 41 - 46 on the conductive layer 2. The conductive layer is removed within the engraving lines, exposing the insulating substrate. After being divided by the engraving lines, a working electrode E, a counter electrode D, and a reference electrode C are formed on the conductive layer. When the laser etching is completed, a large electrode card is obtained. The large electrode card on the insulating substrate contains a plurality of sensor basic units A arranged side by side that can be used to fabricate finished biosensors. Each sensor basic unit A includes an insulating substrate, an electrode system formed by being divided by the engraving lines, engraving lines, and other regions formed by etching. In this example, the electrode system includes a working electrode E, a counter electrode D, a reference electrode C, and a short - circuit prevention region.

[0048] As Figure 4 shown, after laser etching, two rows of sensor basic units A are formed with their heads and tails arranged in sequence (the contact ends of two sensor basic units A are set opposite to each other vertically); where N represents from 0 to n, and "a total of N" means including N sensor basic units A.

[0049] In step 1 of the laser etching of the electrode pattern, the etching walking route of the engraving lines within the conductive layer is custom - set through software. For the specific implementation methods such as the path and direction of the engraving lines, they can be artificially designed and software - controlled according to the requirements of the actual product, and there is not only one path. Similarly, the software can also apply different laser engraving parameters to the engraving lines. The range of the obtained engraving line width is 0.020 mm to 0.200 mm. In this example, the preferred engraving line width is 0.080 mm. Based on the basic performance of the laser etching equipment, some equipment and software can also achieve a complete stripping mode for the pattern. The specific implementation method will be introduced later.

[0050] The material of the insulating substrate is polyvinyl chloride, polyethylene terephthalate, polyethylene terephthalate glycol ester, polyethylene glycol ester, etc. In this example, polyethylene terephthalate glycol ester is preferred.

[0051] The material of the conductive layer 2 can be gold, silver, platinum, palladium, carbon, graphite, conductive glass, etc., as well as other conductive metals or non - metals not limited to this, or their mixtures. The conductive layer covering method can be printing, coating, electroplating, sputtering, etc. In this example, a conductive carbon layer (carbon film) formed by coating is used. The thickness of the carbon layer is 1 - 30 μm. The thickness used in this example is about 8 μm. The resistance of the conductive layer is 10 Ω / □ to 100 Ω / □. In this example, 30 Ω / □ is preferred.

[0052] Some or all of the electrodes of the biosensor can be configured with a reagent layer. The reagent layer uses specific enzymes to quantitatively or qualitatively analyze the measured target substance in the environment of a buffer system, and generally contains the following components: enzymes, electron mediators, polymers, disintegrants, surfactants, stabilizers, and buffer systems. According to the needs of the detection item, the enzyme is selected from one or several of glucose oxidase, glucose dehydrogenase, lactate oxidase, lactate dehydrogenase, uric acid oxidase, cholesterol oxidase, or D-3-hydroxybutyric acid oxidase, etc.; the electron mediator is selected from one or several of ruthenium compounds, potassium ferricyanide, ferrocene, etc.; the buffer system is any one or more of sodium succinate, sodium citrate, piperazine buffer, propanesulfonic acid, PBS buffer, or sodium fumarate; the disintegrant is any one or several of cross-linked PVP, sodium carboxymethyl starch, cross-linked CCNa, etc.; the surfactant is any one or several of anionic surfactants, cationic surfactants, zwitterionic surfactants, or non-ionic surfactants; the stabilizer is one or several of maltitol, trehalose, BSA, or protein protectant. After the above components are formulated, they are fully stirred to make the components fully dissolved and dispersed to form a uniform solution. In this example, as Figure 1 The biosensor shown in

[0053] In step 2 of configuring the reaction reagent, methods such as spotting, screen printing, drop coating, Slot-Die coating, etc. are often used to configure the reagent mixture with a certain chemical composition onto a specific electrode of the biosensor to form a reagent layer. In this example, screen printing is preferably used to configure the reagent on the specific electrode in a specific pattern and position. The biochemical reagent in the specific pattern and position can react with the substance to be detected in the sample and generate a certain electrical signal. The electrical signal is conducted to the detection instrument through a conductive material and fed back to the user. The screen used for screen printing is generally made of materials such as polyester, nylon, stainless steel, etc., with a mesh count generally ranging from 250 mesh to 420 mesh, the wire diameter of the screen used generally ranging from 27um to 120um, and the maximum tension it can withstand generally ranging from 22 to 38N / cm; in this example, a nylon screen with 305 mesh and a wire diameter of 34um is preferably used, and the maximum tension it can withstand is 33N / cm.

[0054] The biochemical reagent with a fixed pattern and position obtained by the above screen printing contacts the sample in the injection channel and reacts with the substance to be detected in the sample. The injection channel is formed between the opening groove 81 and the upper cover 9, and the surface of the upper cover facing the injection channel is made of a hydrophilic layer material. Specifically, the material of the middle layer is usually a PET substrate, and an acrylic resin system is coated as an adhesive material. The thickness of the middle layer generally ranges from 75um to 150um, and the width of the opening groove generally ranges from 0.7mm to 1.8mm. In this example, the thickness of the middle layer is preferably 100um, and the width of the hollow structure is preferably 1.2mm.

[0055] The upper cover 9 has a vent hole 91 at the tail of the sampling channel. The shape of the vent hole can be circular, square, rectangular, linear or other shapes. In this example, the shape of the vent hole is preferably rectangular. In this example, the hydrophilic material is preferably 9901P produced by 3M. The vent holes of the hydrophilic material can ensure that the original air in the cavity is smoothly discharged when the blood sample flows into the sampling channel, ensuring that the sample can smoothly flow into the cavity.

[0056] The color layer is generally a printable single-sided adhesive, and the commodity name is generally printed on the surface, which plays the role of facilitating the identification of the commodity and protecting the biosensor from scratching damage.

[0057] Step 5 is an optional step. For example, if the upper cover itself can be printed with the commodity name and can simultaneously perform a function similar to that of the color layer, then step 5 can be omitted. Or, if the biosensor does not require a color layer, then step 5 can be omitted.

[0058] During the production process, the material that has been laminated with the middle layer, the upper cover, and the color layer and has multiple sensor basic units A is generally called a semi-finished large card. Or, the material that has completed steps 1 to 4 or steps 1 to 5 is called a semi-finished large card.

[0059] In cutting step 6, a cutting tool is used along a preset cutting line. Specifically, the cutting tool is along the Figure 4 cutting lines shown by the horizontal dotted line 50 and the vertical dotted line 51 in the figure, and the semi-finished large card is cut to obtain the finished biosensor. Suitable cutting methods include but are not limited to hob rolling cutting, die punching, chopping, etc. Specifically, in this example, it is preferably to use a hob to roll-cut the semi-finished large card as shown in Figure 4 into a semi-finished long strip sheet containing several sensor basic units A as shown in Figure 5 shown in the figure, and then use a hob to cut the semi-finished long strip sheet along the vertical dotted line 51 to obtain the finished biosensor. To more intuitively illustrate the cutting position of the hob, when using Figure 4 and 5 as the introduction of the cutting process in step 6, the middle layer and the upper cover are not shown in Figure 4 and 5 shown in the figure. The cutting process described in step 6 is one of the important steps in sensor assembly, and its effect directly affects the final passing rate of the sensor and the finished product effect of the sensor. The dotted lines marked on Figure 4 and Figure 5 do not exist during the actual product processing, and the same applies hereinafter. After cutting, the positions of the dotted lines 50 and 51 are the side lines of the biosensor, or can also be called the edge of the biosensor or the side of the biosensor.

[0060] During the cutting process of the full-page semi-finished product, in order to ensure the passing rate of the finished product, after the hob rolls and cuts the large semi-finished card into strip-shaped sheets along the preset horizontal dotted line 50, the quality inspector in the production process first checks whether the engraving lines 41 and 42 in the upper sample channel exist intact. If they exist intact, it can be determined that the strip-shaped sheets obtained by cutting are semi-finished products of qualified products. After the hob cuts the strip-shaped sheets along the preset vertical dotted line 51, the quality inspector in the production process checks again whether the cutting position is in the gap between the two sensor units, that is, if the finished biosensor can completely see the bilateral engraving lines 31 and 32, it is a qualified product biosensor. For the biosensor obtained after cutting, if its engraving lines 31, 32, 41, and 42 are complete engraving lines, it indicates that the produced biosensor is a qualified product. Therefore, by using the engraving lines 31, 32, 41, and 42 as the quality inspection lines to inspect the integrity of the engraving lines 31, 32, 41, and 42 during the production process, defective products with unqualified cutting can be effectively removed.

[0061] However, due to the mechanical shearing force of the cutting tool on the conductive layer, the conductive particles remaining in the engraving lines are very difficult for quality inspectors to identify with the naked eye. The main risks generated are that it may cause a short circuit between adjacent electrodes or electrical conduction between the electrode and non-electrode conductive block areas other than the electrodes. The obtained sensors are also defective products and cannot enter the next production process. In order to eliminate the risk of such defective sensors, the present invention proposes a design scheme that uses engraving lines and conductive wire side edges to form a short-circuit prevention area. The following is a specific elaboration with examples. Figure 6 To make a specific elaboration.

[0062] Compared with Figure 1 At the contact end of the biosensor, Figure 6 The biosensor shown has an engraving line 42 at the contact end. The non-electrode conductive blocks C1, D1, and E1 are jointly enclosed by the engraving line 42 and the engraving lines 31, 32, 33, 34 and the biosensor side edge 24. More specifically, the non-electrode conductive block C1 is enclosed by the engraving lines 42, 31, and 33 and the biosensor side edge 24; the non-electrode conductive block D1 is enclosed by the engraving lines 42, 33, and 34 and the biosensor side edge 24; the non-electrode conductive block E1 is enclosed by the engraving lines 42, 34, and 32 and the biosensor side edge 24. The non-electrode conductive blocks C1, D1, and E1 located at the contact end of the sensor are directly adjacent to the biosensor side edge 24 and are independent of each other. Taking the non-electrode conductive blocks D1 and E1 as examples, as Figure 6Enlarged view of the selected area L of the sensor contact end, where X is the conductive particle X remaining in the engraving line 34 when the cutting tool cuts along the preset route to obtain the sensor edge 24. The conductive particle X connects the non-electrode conductive blocks D1 and E1 that were originally separated by the engraving line 34 and not connected, resulting in a short circuit between D1 and E1. Due to the existence of the engraving line 42, the non-electrode conductive block D1 and the electrode D, and the non-electrode conductive block E1 and the electrode E are separated by the engraving line 42 and not connected. That is to say, even if a short circuit occurs between D1 and E1, the electrodes D and E are still in an open circuit state with each other and will not be affected by the conductive particle X remaining in the engraving line 34. The conductive blocks D1 and E1 are the short-circuit prevention areas of the sensor contact end, which can prevent electrical conduction between the electrodes D and E due to the conductive particle X falling into the engraving line 34.

[0063] Similarly, as Figure 6 shown, compared with Figure 1 , in the sensor sample contact end, the engraving line 32 extends to the biosensor edge 22. The non-electrode conductive block B1 is enclosed by the engraving line 41, the engraving line 32, 43, and the biosensor edge 21, and the non-electrode conductive block A1 is enclosed by the engraving line 41, the engraving line 32, and the biosensor edges 21 and 22. The non-electrode conductive blocks A1 and B1 at the sensor sample contact end are directly adjacent to the biosensor edge 21 and are independent of each other, as Figure 6 the enlarged view of the selected area R of the sensor sample contact end in the figure, where X is the conductive particle X remaining in the engraving line 41 when the cutting tool cuts along the preset route to obtain the sensor edge 21. The conductive particle electrically conducts the conductive blocks A1 and B1 that were originally separated by the engraving line 41 and not connected, resulting in a short circuit between A1 and B1. Due to the existence of the engraving line 32, the non-electrode conductive block A1 and the non-electrode conductive block A, and the non-electrode conductive block B1 and the electrode B are separated by the engraving line 32 and not connected. That is to say, even if a short circuit occurs between A1 and B1, the non-electrode conductive block A and the electrode B are still in an open circuit state with each other and will not be affected by the conductive particle X remaining in the engraving line 41. The non-electrode conductive blocks A1 and B1 are the short-circuit prevention areas of the sample contact end, which can prevent electrical conduction between the electrode B and the conductive block A, thereby avoiding the change in the area of the electrode B due to the conductive particle X remaining in the engraving line.

[0064] Through the design of the short-circuit prevention area jointly composed of the biosensor edge and the engraving line, it can effectively prevent electrical conduction between electrodes or between the electrode and the conductive layer other than the electrode, greatly improving the accuracy of the product and the passing rate of the finished product.

[0065] Figure 6-1 is an improved design based on Figure 6 . As Figure 6-1As shown in a of [Figure Reference], the non - electrode conductive block area around the sensor, which is jointly enclosed by the engraving lines 41, 42, 31, 32 and the biosensor side lines 21, 22, 23, 24, can also be regarded as a form of short - circuit prevention area, and the function of this short - circuit prevention area is consistent with the previous example. As Figure 6-1 As shown in b of [Figure Reference], all engraving lines that may extend to the biosensor side lines only terminate at the engraving lines 41, 42, 31, 32. The non - electrode conductive block area around the sensor, which is jointly enclosed by the engraving lines 41, 42, 31, 32 and the biosensor side lines 21, 22, 23, 24, is still another form of short - circuit prevention area, and it can still prevent electrical conduction between electrodes or between the electrodes and the conductive layer outside the electrodes due to conductive particles generated by cutting.

[0066] As Figure 6-2 shown in the biosensor, it includes electrode C, electrode D, and electrode E, as well as non - electrode conductive blocks B1, D1, etc. In Figure 6-2 the design scheme, electrode E is adjacent to electrode D and non - electrode conductive block D1, where the non - electrode conductive block D1 is located between electrode D and the biosensor edge 24. As Figure 6-2 shown in the enlarged view at L of [Figure Reference], after the tool cuts, even if conductive particles X fall on the engraving line 34 near the sensor edge, it will not cause a short - circuit between electrode E and electrode D.

[0067] Example 2 Blood Glucose Detection Data

[0068] Next, the present invention will be further described in conjunction with the attached drawings and the solution of Example 1 Figure 2 and 6 as follows.

[0069] As Figure 2 shown, the glucose biosensor of this embodiment includes: an insulating substrate 1, a conductive carbon layer 2, a reagent layer 6, a septum layer 8, and an upper cover 9. Specifically, the glucose biosensor of this embodiment includes a conductive carbon coating 2 with a uniform thickness prepared on the insulating substrate 1 by a coating process, on which laser engraving lines such as 31, 32, 33, 34, 41, 42, 43, 44, 45, 46 are etched according to a reasonable programming design using laser etching technology. The laser engraving lines ablate the conductive layer to expose the insulating substrate, thereby forming non - connected electrodes C, D, and E on the conductive layer 2; the reagent layer 6 is located on the electrodes and within the sample injection groove 81 of the septum layer 8. An upper cover 9 is covered on the septum layer 8, and the air holes 91 thereon are located at the bottom of the sample injection groove 81 of the septum layer. The sample injection groove 81 of the septum layer, the hydrophilic upper cover 9 thereon, and the air holes 91 form a blood sample injection channel.

[0070] After inserting the glucose sensor into the testing instrument, start the testing instrument. The blood sample is aspirated into the injection channel by siphon action, and the air originally in the injection channel is discharged through the upper cover air hole 91 at the end of the injection channel, effectively ensuring the smoothness of the blood flowing into the channel. When the channel is filled with blood, a DC voltage of 200 - 500 mv is applied to the electrode to cause an oxidation-reduction reaction between the reagent layer 6 and the glucose to be measured in the blood, and a test current is generated. The testing instrument performs appropriate calibration compensation based on the detected current value and the ambient temperature measured by the temperature sensor, and converts it into a blood glucose value for display to the user.

[0071] The materials of the reagent layer 6 mainly include glucose dehydrogenase FAD-GDH, potassium ferricyanide, and a second electron mediator; the enzyme activity of glucose dehydrogenase is 200 - 600 U / mg.

[0072] The above glucose sensor is used to test 11 blood samples with different glucose concentrations at room temperature. The hematocrit of the blood samples with different concentrations is adjusted to 42% ± 2% before testing, and its specific concentration is measured by a glucose lactate analyzer of model YSI 2300 produced by YSI Company in the United States. Each blood sample with a certain concentration is tested 10 times, and the test results are shown in Table 1.

[0073] Table 1: Test Results of Glucose Sensor

[0074] YSI Reading (mg / dl) 11 23 47 83 106 174 224 325 453 547 647 Reading 1 LO 25 48 83 104 175 230 329 461 520 HI Reading 2 LO 26 46 84 100 170 229 323 452 518 HI Reading 3 LO 26 47 82 108 181 238 317 455 529 HI Reading 4 LO 25 47 82 104 172 228 324 461 522 HI Reading 5 LO 24 46 84 102 175 229 327 459 554 HI Reading 6 LO 24 47 83 101 175 221 317 459 520 HI Reading 7 LO 25 47 81 97 178 235 323 459 540 HI Reading 8 LO 26 48 83 99 172 235 328 476 561 HI Reading 9 LO 23 46 81 99 174 221 319 474 515 HI Reading 10 LO 25 46 81 100 176 225 326 469 522 HI Average Value ---- 24.9 46.8 82.4 101.4 174.8 229.1 232.3 462.5 530.1 ---- Standard Deviation ---- 0.99 0.79 1.17 3.20 3.16 5.76 4.40 7.92 16.11 ---- Test Precision ---- 4.0％ 1.7％ 1.4％ 3.2％ 1.8％ 2.5％ 1.4％ 1.7％ 3.0％ ---- Test Deviation ---- 2.0 -0.6 -0.2 -4.2％ 0.4％ 2.2％ -0.6％ 2.2％ -3.0％ ----

[0075] Taking the average value of 10 repeated tests of blood at each glucose concentration and comparing it with the test results of YSI 2300, it can be seen that in the extremely low glucose concentration range (less than 20 mg / dl) and the extremely high glucose concentration range (greater than 600 mg / dl), the instrument test results show LO and HI respectively. Except for these extreme concentrations, the test deviation of the glucose sensor is very small, the accuracy is relatively high, and the coefficient of variation of the test values of the same blood sample is within 3%, and the precision fully meets the requirements.

[0076] Figure 7 It is a linear graph of the test values of the glucose sensor in Example 2 and the test values of YSI, and its fitting equation is y = 0.9888x + 1.7767; R 2 = 0.9986. It can be seen that the glucose sensor has a good linearity.

Claims

1. A biosensor, comprising an insulating substrate, a sample inlet, a sample injection channel for allowing a test sample to enter, a conductive layer disposed on the insulating substrate, engraved lines distributed on the conductive layer, and electrodes formed by dividing the engraved lines, wherein a reagent layer is provided on part or all of the electrodes located in the sample injection channel area, and is characterized in that, On the path where two adjacent electrodes extend toward the edge of the biosensor, at least one electrode does not extend to the edge of the biosensor; or on the path where an electrode and an adjacent non-electrode conductive block extend toward the edge of the biosensor, at least one of the electrode or the non-electrode conductive block does not extend to the edge of the biosensor.

2. The biosensor according to claim 1, characterized in that, A non-electrode conductive block is provided between at least one of two adjacent electrodes and the edge of the sensor.

3. The biosensor according to claim 1, characterized in that, An anti-short circuit area is provided between the electrode that does not extend to the edge of the biosensor or the conductive block that does not extend to the edge of the biosensor and the edge of the biosensor.

4. The biosensor according to claim 1, characterized in that, The anti-short circuit area is formed by enclosing the edge of the biosensor and the engraving line.

5. The biosensor according to claim 1, characterized in that, Neither adjacent electrodes extend to the edge of the biosensor, or neither adjacent electrodes nor non-electrode conductive blocks extend to the edge of the biosensor.

6. The biosensor according to claim 1, wherein The engraved lines on the conductive layer do not intersect with the edges of the biosensor.

7. The biosensor according to claim 1, wherein The conductive layer is selected from gold, silver, platinum, palladium, carbon, graphite, conductive glass, or a mixture thereof.

8. A method for preparing a biosensor, comprising the following steps: On a raw material having an insulating substrate and a conductive layer, engraving lines are etched on the conductive layer, and electrodes are divided by the engraving lines; a prepared reagent is added to the corresponding electrodes; an intermediate layer and an upper cover are sequentially attached to the electrodes to form a biosensor with an injection channel; the method is characterized in that, along the path where two adjacent electrodes extend toward the edge of the biosensor, at least one electrode does not extend to the edge of the biosensor; or On the path where the electrode and the adjacent non-electrode conductive block extend toward the edge of the biosensor, at least one of the electrode or the non-electrode conductive block does not extend to the edge of the biosensor.

9. The method according to claim 7, characterized in that: A non-electrode conductive block is provided between at least one of the two adjacent electrodes and the edge of the sensor.

10. A method for avoiding short - circuit of a biosensor electrode, characterized in that, On the path where two adjacent electrodes extend toward the edge of the biosensor, at least one electrode does not extend to the edge of the biosensor; or on the path where an electrode and an adjacent non-electrode conductive block extend toward the edge of the biosensor, at least one of the electrode or the non-electrode conductive block does not extend to the edge of the biosensor; or between two adjacent electrodes, a non-electrode conductive block is provided between at least one of the electrodes and the edge of the sensor.

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