DE10018959B4 - Biosensor with multiple sampling routes - Google Patents

Abstract

A biosensor for detecting levels of biochemical components in a sample comprising:
An electrically insulating substrate;
An anode disposed on the substrate, the anode being formed at each end of the anode with a working electrode and an anode connector, respectively;
A cathode disposed on the substrate, the cathode being formed at each end of the cathode with a reference electrode and a cathode connector, respectively;
A reaction layer having an area disposed on the working electrode and the comparison electrode, the reaction layer being used for contacting and reacting with the sample;
Electrically insulating layers 10 and 10 'on the substrate 2 with an opening 11 (having a height of about 0.25 to 0.3 mm) for receiving the sample on the reaction layer 9 and an opening end 12; and
A net-shaped covering layer, wherein the net-shaped covering layer 13 comprises the electrically insulating layer 10 and ...

Description

Background of the invention

Technical area

The The present invention relates to a biosensor, in particular a Strip biosensor (current strip biosensor) for detecting levels of biochemical Substances.

Description of the state of technology

biochemical Analyzers are generally divided into three categories: wet types, dry types and biosensors. The biochemical analyzers wet types mix samples and reagents (usually a color reagent) for reaction and then detect one Color difference by optical instruments, such as colorimeter or Spectrophotometer. The wet type analyzers can not Use whole blood as a sample because whole blood requires pretreatment. Furthermore, the wet type analyzers require expensive equipment and qualified personnel for operation. That's why they usually become applied in clinics and research centers. In the case of biochemical Dry type analyzers become the test strips after the surfaces the test strip is coated with chemical reagents, enzymes or antibodies subsequently directly contacted with the samples for analysis. Although the procedures for the preparation of the reagents and the operation are simplified based the detection still on colorimetry. The test strips of the analyzers The dry type is subject to oxidation and discoloration. The test strips can because of the disturbing Influence of color can not be used with whole blood.

Of the Biosensor is from a biological device, a membrane device and a transducer. The biological device is a biological material that has a specific ability to discriminate such as microorganisms, cells, tissues, enzymes, antigens and antibodies. The membrane device is generally a polymeric material for Fixing the biological device and screening of interfering substances. The transducer contains Electrodes, an ion selection field effect transistor, a heat sensitive Resistor, a thermistor, a piezoelectric device, optical fibers, a photocell and a sound wave counter. The Peroxidase electrode is one of the most common transducers for biosensors.

For example becomes glucose oxidase in blood glucose monitoring with biosensors a membrane fixed on the surface of a columnar peroxidase electrode is attached. Subsequently are attached to a platinum anode and a silver / silver chloride cathode Polarization potentials applied. The glucose oxidase catalyses the glucose for the production of hydrogen peroxide. hydrogen peroxide will be near the anode surface further oxidized to water and then releases electrons. The released Electrons are used to increase the glucose concentration in the To calculate samples.

The aforementioned columnar electrode has the following disadvantages: it must be polished frequently, the membrane It is difficult to fix on it and it is difficult to clean. It also has the disadvantage that it is the cross contamination is exposed and difficult to calibrate. Furthermore, she is heavy in a form for make the one-time use and requires high production costs. It is impractical in the application. To overcome the disadvantages of columnar electrode Test strip electrodes are developed which are favorable for industrial production are.

US Pat. 5,120,420 A discloses a biochemical detection electrode strip including an electrode part, an insulating layer, a reaction layer, and a sample receiving space formed by applying a synthetic resin plate and a hydrophilic cover to the reaction layer. The room contains a sample inlet and an air outlet. The reaction layer is prepared by sequentially coating an electrode base plate with a carboxymethyl cellulose (CMC) solution, drying the CMC layer, spraying a glucose oxidase solution (GOD) and drying it, and coating with an organic suspension containing a conductive medium and drying the same formed to form a biochemical reaction surface. The biochemical detection electrode strip is completed by applying the resin plate and the hydrophilic cover to form the sample receiving space on the base plate.

The biochemical detection electrode strip has the following disadvantages. First, there are three steps required to form the reaction layer, namely, formation of the CMC layer to improve the hydrophilic property of the carbon electrode surface, formation of the GOD layer, and formation of the conductive medium. Each step requires a subsequent drying step. The process is complex. Second, there is only one sample inlet. The sample is introduced into the reaction zone by contacting it with a tip of the electrode strip.

US Pat. 5,628,890 A discloses another biochemical detection electrode strip comprising an electrode part, an insulating layer, a reaction layer, a double layer of hydrophilic mesh on the reaction layer and a covering layer on the mesh layers. The electrode portion includes three electrodes in which a carbon layer is printed first and then a silver layer is printed thereon. A bioactive substance, silver / silver chloride and a conductive medium are deposited on a working electrode, a reference electrode. and a counting electrode disposed in the reaction zone. Subsequently, the double layer of braid is placed on the reaction zone, the braid layer should be hydrophilic for the access of the sample to the reaction zone. A blood sample in the hydrophilic mesh layers will remain limited due to the hydrophilic affinity on the reaction layer. Subsequently, the cover layer is adhered to the mesh layers and leaves a sample inlet therein. The detection electrode strip described above has the following disadvantages: it is complex, requires multiple mesh layers and hydrophilic operation. In addition, there is only one sample inlet and it is difficult to determine if the samples are properly incorporated into the reaction zone. In addition, more than μl of blood sample is required.

Summary of the invention

The present invention is to overcome the disadvantages of the prior art and to provide an efficient biosensor that is easy to manufacture and to detect. Reactive substances are mixed in one step and introduced into the reaction layer. A reticular covering layer is placed on a sample inlet to establish capillary attraction between the reticular covering layer and the reaction layer. The reticular covering layer and the resulting capillary attraction facilitate sampling when a sample is introduced from an opening end on one side of the biosensor. When the reticular covering layer is hydrophilic, a sample may be introduced from the upper part of the biosensor by hydrophilic affinity. Finally, in the international patent application WO 98/24366 A2 a biosensor is described in which there is a reticulated blood-conducting layer between the cover and the substrate. This configuration allows the supply of a sample only from above, also the reticular layer is accessible only in the region of the opening.

A Object of the present invention is a biosensor with multiple Provide sampling points. The type of sampling can be achieved are by dropping a sample on the biosensor or approximating the Biosensors to the sample, for example a drop of blood on one Earlobe. He allows in a practical way the sampling.

A Another object of the present invention is to provide a biosensor, which can quickly and easily introduce a sample into the reaction layer. The sample can be effective for the detection can be obtained.

A Another object of the present invention is to provide a biosensor, which reduces the required sample quantities. The required Amount of sample blood can be reduced to 5 μl. The patient must be lower Endure pain.

A Another object of the present invention is to provide a biosensor, which does not require several drying steps and one on one surface can form a uniform and shallow reaction layer. He is easy to manufacture and can meet the measurement accuracy requirements fulfill.

In order to achieve the above-mentioned objects and avoid the disadvantages of the prior art, the present invention discloses a biosensor for detecting contents of biochemical components in a sample comprising: an electrically insulating substrate; an anode disposed on the substrate, the anode being formed at both ends of the anode with a working electrode and an anode connector, respectively; a cathode disposed on the substrate, the cathode being formed at both ends of the cathode with a reference electrode and a cathode connector, respectively; a reaction layer having a zone disposed on the working electrode and the comparison electrode, the reaction layer being used for contacting and reacting with the sample; one arranged on the substrate electrically insulating layer having an opening for receiving the sample on the reaction layer and an opening end; and a reticular covering layer on the reaction layer, the reticular covering layer covering at least a part of the opening. The sample may thus be introduced into the reaction layer from above the reticular covering layer by hydrophilic affinity of the reticular covering layer, or from the opening end by capillary attraction between the reticular covering layer and the reaction layer. The reaction layer is of a formulation containing an enzyme, a carrier, an electrical medium and a surface-active agent.

The reticular Covering layer of the present invention is a hydrophilic reticulated material or a hydrophobic net-shaped Material or a wire mesh, which is a Kapillaranziehung Provides the sample easy and effective from the opening end on one side of the biosensor for detection on the reaction layer introduce. The opening end serves as a sample contact point for sampling by a patient approximated can be. The sample can be transferred from the opening end to the reaction layer introduced for detection become. By simply approaching and touching of the patient, the biosensor can effectively secure the sample. He is Practical handling of the sampling. In a preferred embodiment the substrate further has a semicircular protruding part under the opening end as a sample contact point. The semicircular protruding part is not only distinguishable and can be brought closer to the sample be to facilitate the sampling, but also can the Reduce pain of the patient.

By the disclosure of the invention will obtain various advantages. A manufacturer of biosensors can lower the biosensors to a more favorable one Making an analyst can reduce the samples to a more favorable one and more effective way, and a patient can get his / her inconvenience to a minimum. This can be an accurate detection result to be obtained.

The The above and other objects and advantages of the invention and the way in which it is achieved becomes clearer will be communicated on the basis of the following detailed description with the accompanying drawings.

Short description of the drawings

1 is an exploded view of the biosensor according to an embodiment of the invention;

2 is perspective view of the biosensor of 1 ;

3 is a top view of the biosensor of 1 ;

4 is a section through the biosensor along the line AA of 3 ; and

5 Fig. 10 is a comparison chart of blood glucose concentrations between the detection result of the biosensor of the present invention and that of a YSI glucose analyzer.

Detailed description of the invention

Referring to 1 to 4 , contains a biosensor 1 according to an embodiment of the invention for detecting levels of biochemical components in a sample: an electrically insulating substrate 2 ; one on the substrate 2 arranged anode 3 , wherein the anode 3 with working electrodes 4 (as in 3 shown) or an anode connection part 5 on one side of the anode 3 is provided; and one on the substrate 2 arranged cathode 6 , where the cathode 6 with reference electrodes 7 (as in 3 shown) or a cathode connector 8th on each side of the cathode 6 is provided.

The substrate 2 is electrically insulated and has a flat surface. The substrate 2 should be at temperatures of 40 to 200 ° C in a thermal process that is used to control the electrical conductivity and the adhesion of the anode 3 and the cathode 6 to increase, be thermally resistant. Suitable materials for the substrate 2 include, but are not limited to: PVC, polyester, bakelite, glass fibers (FR-4), PET, PC, PP, polyethylene, PA, PS, glass, and ceramics (CEM-1).

The anode 3 and the cathode 6 are made of two spaced conductive films which are connected to a detection device (not shown in the figures).

After being partially covered with electrically insulating layers 10 and 10 ' has been covered, the anode becomes 3 at both exposed ends of the anode with an anode connector 5 for connection to the detection equipment and a working electrode 4 on which the bioactive layer is arranged, that is, the reaction layer 9 (please refer 4 ), educated. The working electrode 4 is used to transmit electrical signals induced by chemical or biochemical reactions of the sample on the detection device. After getting off the electrically insulating layers 10 and 10 ' has been covered, the cathode becomes 6 at both exposed ends with a cathode connector 8th for connecting the detection device or the reference electrode 7 (please refer 3 ), on which the reaction layer 9 is arranged, shaped. The reference electrode 7 will work in collaboration with the working electrode 4 used to detect the electrical signals from the samples.

The biosensor according to the invention 1 further comprises a reaction layer 9 on the working electrode 4 and the reference electrode 7 , The reaction layer 9 does not overlap the electrically insulating layer 10 ,

The reaction layer 9 is formed by placing a formulation of bioactive substances on a part of the substrate 2 , the anode 3 and the cathode 6 , The formulation of the reaction layer comprises an enzyme, a carrier, an electrical medium and a surface-active agent. In one embodiment, the carrier comprises from 0.05% to 1.5% by weight of the composition. The carrier includes microcellulose, methylcellulose, carboxymethylcellulose, starch, vinyl alcohol, vinylpyrrolidone, PVA, PVP, PEG or gelatin. An appropriate recipe is described below:
An enzyme such as glucose oxidase at a dosage of about 200 to 1200 U / ml;
an enzyme preservative at a dosage of about 0.1 to 1.0% by weight of the formulation, which protective agent may include albumin, dextrin, dextran or amino acids, which may be used alone or in combination;
an electrical medium at a dosage of 2.0 to 10.0% by weight of the formulation, wherein a suitable electrical medium includes potassium ferricyanide; and
a surfactant at a dosage of less than 0.1% by weight of the formulation wherein a suitable surfactant is polyoxyethylene ether (polyethylene glycol ether) surfactants (such as Triton X-100, Triton X-405, Triton X-114), sodium lauryl sulfate, polyoxyethylene sorbit (such as Tween 20, Tween 40, Tween 60 and Tween 80) or other water-soluble surfactants or detergents.

The biosensor 1 The present invention further includes electrically insulating layers 10 and 10 ' on the substrate 2 with an opening 11 (with a height of about 0.25 to 0.3 mm) for receiving the sample on the reaction layer 9 and an opening end 12 , The electrically insulating layers 10 and 10 ' are made of PP, PVC, PET, PC, PE or other insulating plastic materials.

After the electrically insulating layers 10 and 10 ' on the substrate 2 have been arranged, the exposed ends of the anode 3 or the cathode 6 formed at one end with an anode connector 5 and a cathode connector 8th , and at the other end within a range through the opening 11 is limited, become a working electrode 4 and a reference electrode 7 educated. In a preferred embodiment, the area of the working electrode 4 two to three times the area of the reference electrode 7 ,

A reaction zone for receiving the sample for reaction refers to a zone passing through the opening 11 and the reaction layer 9 below the opening 11 is limited. The thickness of the electrically insulating layer 10 over the reaction zone is generally 0.2 mm to 0.3 mm.

The biosensor according to the invention 1 further comprises a net-shaped cover layer 13 to protect the reaction layer 9 and the capillary action with the sample on the electrically insulating layer 10 to increase. The net-shaped covering layer 13 covers at least part of the opening 11 and the electrically insulating layer 10 , By Kapillaranziehung between the reticular cover layer 13 and the reaction layer 9 can take a sample from the opening end 12 on the reaction layer 9 be received.

The net-shaped covering layer 13 is made of a hydrophilic reticulated material or a hydrophobic reticulated material or a wire mesh having a mesh number of preferably 60 to 300. When the reticular covering layer 13 made of a hydrophilic net-shaped material, a hydrophilic sample may be from the opening end 12 or from above the reticular covering layer in the direction 'a' of 4 be introduced. When the reticular cover layer 13 is made of a hydrophobic reticulated material, a hydrophilic sample with lower affinity of the opening end 12 introduced by capillary action. The net-shaped covering layer 13 may also be a hydrophobic reticulated material coated with a surfactant including polyoxyethylene ethers (such as Triton X-100, Trion X-405, Triton X-114), sodium lauryl sulfate, polyoxyethylene sorbitan (such as Tween 20, Tween 40, Tween 60, Tween 80). or other water soluble surface active agents or detergents.

The biosensor according to the invention 1 shows two ways of introducing the sample onto the reaction layer 9 on. When the reticular cover layer 13 is hydrophilic, the samples in a first sample insertion direction 'a' of 4 by hydrophilic attraction passing through the hydrophilic reticular covering layer 13 or a sample may be introduced from a second sample introduction direction 'b' of FIG 4 be introduced by Kapillaranziehung. In the direction 'b', the biosensor 1 can be approximated directly to the sample and the sample can be fast and peppy from the reaction layer 9 be attracted. Not only can detection results be secured, but also the quantitative requirements for the sample can be reduced. Furthermore, if the reticular cover layer 13 is hydrophobic, a sample in the second sample introduction direction 'b' in the reaction layer 9 be introduced. This is done by the biosensor 1 approaching a patient. For example, the patient's ear can be pierced with a lancet, followed by a drop of blood, and then the biosensor becomes 1 approaching the drop of blood, in the second sample insertion direction 'b' on the reaction layer 9 should be introduced. The sample requirement can thereby be reduced as much as possible.

blood samples needed by a diabetic, around on blood sugar test strips to be applied. Especially with a patient who is serious is sick, become daily frequent Blood samples needed to monitor the patient. If the blood requirement can be reduced, a finer lancet can be used can be applied and the pain of the patient can be kept to a minimum be reduced. Furthermore, the Blood sample should be wiped if the sample is on a conventional Test strip is applied and the sample size is not big enough is what leads to measurement errors to lead can. The invention can reduce blood demand and can be conventional Improve sampling methods.

In a preferred embodiment, the substrate 2 of the biosensor 1 a semicircular protruding part 14 below the opening end 12 on, which serves as a sample contact point. The semicircular protruding part 14 allows the biosensor 1 closer to the sampling point and facilitates sampling and helps to reduce the patient's perception when the biosensor touches the patient.

Unlike the earlier ones US patents Nos. 5,120,420 A and 5,628,890 A For example, the present invention provides a single layer of reticulated material on the reaction layer. Since the reticulated material very many stitches at the opening end 12 the reaction zone, capillary attraction will take place and sampling will be facilitated. Both hydrophilic and hydrophobic reticulated materials can be applied to the reaction zone of the biosensor. When the reticular cover layer 13 is hydrophobic, a sample can be introduced in the direction 'b'; if the net-shaped covering layer 13 is hydrophilic, a sample can be introduced in both the 'a' and 'b' directions.

The Process for the preparation of the electrode test strips of the biosensor according to the invention is simplified and the quality of the strip is improved. We will become the manufacturing steps follows summarized.

Step 1

A layer of conductive foil containing an anode 3 and a cathode 6 is screen printed on one of the flat surfaces of a flat substrate plate 2 printed. The conductive film is composed of conductive ink suitable for screen printing, such as carbon ink, silver ink, gold ink, or a combination of silver and carbon inks, or any combination of these inks. For example, the silver ink is printed first followed by the carbon ink. The conductive film is then dried at a temperature of 40 ° C to 150 ° C.

step 2

A 0.01 to 1.0 mm thick electrically insulating layer 10 ' is arranged by film pasting technology on the side on which the conductive film is printed. A 0.25 to 0.3 mm thick electrical isolie layer 10 that have an opening 11 and an opening end 12 is disposed on the reaction zone. The working electrode 4 and the reference electrode 7 are formed by leaving the conductive film partially exposed, and the electrodes 4 and 7 be on the zone through the opening 11 is limited. The through the working electrode 4 and the reference electrode 7 formed zone is referred to here as a reaction zone.

step 3

To form the reaction layer 9 Bioactive substances are added dropwise to the reaction zone and dried at 40 ° C to 60 ° C.

Step 4

On the reaction layer 9 becomes a net-shaped covering layer 13 arranged.

The The present invention will be described according to the following embodiments described in more detail.

example 1

A conductive film of carbon ink is screen printed on a flat surface of a PC substrate plate 2 applied, wherein an anode 3 and a cathode 6 are formed, which are isolated independently. The substrate 2 is dried at a temperature of 130 ° C. Then, a 0.27 mm thick electrically insulating layer of PET is placed on the flat surface to form an anode connector, a cathode connector, a working electrode, and a comparison electrode by partially exposing the conductive film. The zone formed by the working electrode and the reference electrode is the reaction zone.

Subsequently, a composition of the following formulation is dripped onto the surface of the reaction zone, forming a reaction layer: glucose oxidase 0.63% albumin 0.5% potassium 6% methylcellulose 0.5% Triton X-100 (t-octylphenoxypolyethanol) 0.07% Phosphate buffer (pH = 5.0) 92.30%

After this the above-described formulation of bioactive substances of the reaction zone has been added, the test strip is at a temperature from 50 ° C Dried for 15 minutes. Subsequently, a net-shaped cover layer made of polyester, Teterlon T120-54 (mesh 120) arranged on the reaction layer and the current electrode test strip of the Biosensors is completed.

A disposable current electrode test strip is fabricated in this manner and can receive samples in the direction 'b' as in FIG 4 shown, and can determine blood sugar in whole blood samples. The results are in 5 3 shows a comparison of blood sugar concentrations between the results of the biosensor according to the invention and those of a YSI blood sugar analyzer. The coefficient of variation of the test strips according to the invention is less than 5%. The blood requirement for detection is less than 4 μl. The results show that accurate measurements are made with the biosensor of the present invention.

Example 2

Example 2 is substantially similar to Example 1, except that the recipe has been modified as follows: glucose oxidase 0.63% albumin 0.5% potassium 6% carboxymethylcellulose 0,5% Triton X-100 (t-octylphenoxypolyethanol) 0.07% Phosphate buffer (pH = 5.0) 92.30%

Example 3

Example 3 is substantially similar to Example 1, except that the recipe has been modified in the following manner: glucose oxidase 0.63% albumin 0.5% potassium 6% dextran 0.5% Trition X-100 (t-Octylphenoxypolyethanol) 0.07% Phosphate buffer (pH = 5.0) 92.3%

Example 4

Example 4 is substantially similar to Example 1, except that the recipe has been modified in the following manner: glucose oxidase 0.63% albumin 0.5% potassium 6% glutamic acid 0.1% PEG 0.3% Tween 20 (polyoxyethylene sorbitan monolaurate) 0.1% Phosphate buffer (pH = 6.0) 92.37%

Example 5

example Figure 5 is substantially similar to Example 1, except that the reticular covering layer is through a hydrophobic polyester PES-37T (mesh 110) has been replaced is. The manufacturing steps are the same as in Example 1 explained. After a reaction layer has been formed, the reticulated material becomes PES-37T glued to the electrically insulating and the test strips is finished.

Example 6

example Fig. 6 is substantially similar to Example 1, except that the reticular cover layer is through a stainless steel wire mesh is replaced. The manufacturing steps are the same as explained in Example 1. After the reaction layer has been formed, the stainless steel wire mesh is on the electrically insulating Layer glued on and the test strip is completed.

Example 7

example Figure 7 is substantially similar to Example 1, except that the PC board is replaced by a PVC board is replaced. The manufacturing steps are the same as in Example 1 explained. After the reaction layer has been formed, the reticular cover layer becomes glued to the electrically insulating layer and the test strip is finished.

Example 8

Example 8 is substantially similar to Example 1, except that the reticulated cover layer is replaced by PET (polyethylene terephthalate), PET-43T (110 mesh). The reticular cover layer is soaked with 1% Triton X-100 and treated to become hydrophilic. The production steps are the same as explained in Example 1. After the reaction layer has been formed, the reticular cover layer is adhered to the electrically insulating layer and the test strip is completed. rehearse can in the directions 'a' or 'b', as in 4 be introduced shown.

Of the The disclosed biosensor of the present invention does not exclude only the advantages of simplicity of manufacture and accuracy of measurement one, but contains multiple sampling points. Samples may be dropped for release, or the biosensor can be approximated to the samples, taking the sampling is relieved. A sample can be easily and quickly added to the reaction layer introduced become. Furthermore, can The pain of the patient can be reduced by the required Sample amount is reduced. The invention provides a convenient and effective solution for manufacturers, Analyst and patient

The Methods and features of the invention are in the above Examples and the description have been described sufficiently. It should be noted that any Modifications or changes, who do not abandon the idea of the invention, from the scope of the Invention should be.

Claims (15)

A biosensor for detecting levels of biochemical components in a sample, comprising: - an electrically insulating substrate; An anode disposed on the substrate, the anode being formed at each end of the anode with a working electrode and an anode connector, respectively; A cathode disposed on the substrate, the cathode being formed at each end of the cathode with a reference electrode and a cathode connector, respectively; A reaction layer having an area disposed on the working electrode and the comparison electrode, the reaction layer being used for contacting and reacting with the sample; - electrically insulating layers 10 and 10 ' on the substrate 2 with an opening 11 (with a height of about 0.25 to 0.3 mm) for receiving the sample on the reaction layer 9 and an opening end 12 ; and a net-shaped covering layer, wherein the net-shaped covering layer 13 the electrically insulating layer 10 and at least part of the opening 11 the electrically insulating layer on the side facing away from the substrate covers. Biosensor according to claim 1, characterized in that that the reticular Covering layer of a hydrophilic reticulated material or a hydrophobic net-shaped Material or a net-shaped material made of metal wire. Biosensor according to claim 1 or 2, characterized that the reticular Covering layer has a mesh number of 60 to 300. Biosensor according to one of claims 1 to 3, characterized that the reticular Covering layer is a hydrophobic reticulated material that with a surface active Agent has been treated. Biosensor according to claim 4, characterized in that that this surfactants Agent surface-active Polyoxyethylene ether, sodium lauryl sulfate, polyoxyethylene sorbitan or another water-soluble surfactant Agent or detergent is. Biosensor according to one of claims 1 to 5, characterized that this Substrate further a semicircular, protruding part below the opening end, the serves as a sample contact point. Biosensor according to one of claims 1 to 6, characterized that the Reaction layer from a formulation containing an enzyme, a Carrier, an electrical medium and a surfactant produced is. Biosensor according to claim 7, characterized in that that the Carrier a microcellulose, methylcellulose, carboxymethylcellulose, Strength, Vinyl alcohol, vinylpyrrolidone, PVA, PVP, PEG or gelatin. Biosensor according to claim 8, characterized in that that the Carrier 0.05 to 1.5 wt .-% of the formulation. Biosensor according to claim 7, characterized in that the electrical medium is potassium ferricyanide is. Biosensor according to claim 7, characterized in that that this surfactants Agent surface-active Polyoxyethylene ether, sodium lauryl sulfate, polyoxyethylene sorbitan or another water-soluble surfactant Agent or detergent is. Biosensor according to claim 7, characterized in that that this surfactants Agent less than 0.1 wt .-% of the recipe. Biosensor according to one of claims 1 to 12, characterized that the area the working electrode is two to three times the area of the Comparative electrode is. Biosensor according to one of claims 1 to 13, characterized that the electrically insulating layer of PP, PVC, PET, PC, PE or a other insulating plastic material is. Biosensor according to one of claims 1 to 14, characterized that the electrically insulating layer has a thickness of 0.25 to 0.35 mm.