CN2195757Y - Disposable biosensor - Google Patents

Abstract

The utility model belongs to a disposable biosensor that can measure the content of a substance in a solution. The sensor uses a sheet metal as a conductive substrate, and a conductive layer and an insulating protective ring are coated on its surface by a printing process to form a basic electrode. An electron transfer receptor membrane, an immobilized enzyme membrane and an anti-interference membrane are coated on the surface of the basic electrode to form a biosensor that can measure a substance in an aqueous solution. The basic electrode can also be used as an electrochemical detector to determine the concentration of heavy metal ions.

Description

The utility model belongs to a biological sensor capable of measuring the content of a substance in a solution. This biosensor can detect the presence of a substance in an aqueous solution, measure the concentration of a substance, and monitor changes in its concentration over time.

There are many types of biosensors that can measure the content of a substance in a solution, such as metal electrode biosensors based on current measurement, ion-sensitive field-effect transistor biosensors based on potential measurement, optical fiber biosensors, and thermistor biosensors. Although many types of biosensors have been developed at home and abroad, it is difficult to achieve commercialization because the manufacturing process used is not suitable for batch and automatic production. The literature Bioseneors, 3, 317-318 (1998) and Sensors and Actuators B, 8, 59-64 (1992) reported a biosensor that is achievable and suitable for commercial production. The shape of this biosensor is a rectangular sheet. On a polyimide substrate, two silver conductive strips are first printed by screen printing, and a graphite conductive layer is printed on one of them, and then coated with an electron transfer layer. The immobilized glucose oxidase membrane of the body is used to detect glucose; on another silver bar, a silver chloride layer is printed, and then the surface of the thin slice is sealed with an encapsulation material, and the electrode and the chlorine dioxide attached to the immobilized enzyme membrane are exposed at one end of the thin slice. The silver electrode becomes the sensitive part of the measurement sample, and a part of the electrode is exposed at the other end of the sheet, so that the sheet is connected to the measuring instrument. Finally, a nylon mesh is pasted on the sensitive part to protect the immobilized enzyme membrane. In the structure of the biosensor, since the reference electrode and the working electrode are made on the same substrate, they are discarded together with the working electrode after use, thus increasing the analysis cost and causing waste. In addition, the manufacturing process includes the manufacturing process of the reference electrode, so the manufacturing process is complicated. Since the biosensor has a planar structure, there needs to be a certain distance for the transition from the sensitive area to the contact end, so it is difficult to reduce the volume, and it is difficult to realize integrated packaging, which brings inconvenience to carrying and storage.

The purpose of the utility model is to provide a sheet-shaped disposable biological substrate which is sequentially coated with a conductive layer, a protective ring, a chemical modification layer, an immobilized biologically active film, and an anti-interference film by a printing method on a sheet-shaped metal substrate. sensor.

When the biosensor is in contact with the tested solution, the molecules of the tested substance will pass through the anti-interference membrane to reach the immobilized bioactive membrane, while larger molecules or substances with different electrical properties from the tested substance will be blocked. The molecules of the analyte are oxidized by the biologically active substances in the oxidized state (such as enzymes) in the immobilized bioactive film, and at the same time the biologically active substances are converted into a reduced state, and then oxidized by the electronic mediator in the lower layer to return to the oxidized state. The electron mediator becomes reduced at the same time. The electron mediator in the reduced state releases electrons on the surface of the conductive layer at a certain potential, and returns to the oxidized state, and the above process is repeated. The electrons released by the electron medium cause the change of the measurement current, which is transmitted to the measurement circuit through the metal substrate, and the current change detected by the measurement circuit can reflect the concentration of the measured substance.

Compared with the currently existing biosensor, the utility model has a smaller area and volume due to the use of a sheet-like conductive structure, thus saving the volume of manufacturing materials and analysis samples. At the same time, since the separate reference electrodes are used, the manufacturing process is simplified and waste is avoided. The measurement requires a small amount of the sample to be tested, from a few microliters to a few milliliters, and it can work normally. In addition, because the sensor is small in size and shaped like a tablet, it is suitable for mechanized integrated packaging and is easy to carry, store and transport.

The design scheme of this sensor is described as follows in conjunction with accompanying drawing.

Accompanying drawing 1 is the structure diagram of biosensor.

In the accompanying drawing 1 (a), the base electrode is composed of a metal substrate 1, a printed conductive layer 2, and a guard ring 3. The conductive layer can be an adhesive mixed with ultrafine graphite powder, or other inert metal powder, and its function is to form an electrochemically stable, conductive film as the working electrode of the sensor. The protective ring can be water-resistant, acid-alkali corrosion-resistant materials such as silicone rubber, ink, etc. Its function is to limit the geometric size of the central part of the conductive layer as the working electrode in contact with the solution, and isolate the rest of the sensor surface to prevent the immersion of the aqueous solution. eclipse. The basic electrode can be used to detect electrochemically active substances. A chemical modification layer 4, an immobilized bioactive film 5 and an anti-interference film 6 are sequentially formed on the surface of the basic electrode by means of spin coating or dropping. The chemical modification layer is composed of electron mediators, such as ferrocene and its derivatives, benzoquinone, organic dyes, etc. Its function is to catalyze the electrochemical redox process on the electrode surface, reduce the measurement voltage, and lift off the detection sensitivity. Immobilized bioactive membranes can be immobilized enzyme membranes, immobilized microbial membranes, immobilized biological tissue membranes, and immobilized antigen-antibody membranes. electrochemically active product. When measuring different substances, corresponding immobilized bioactive membranes can be selected. The anti-interference film can be cellulose film, ion exchange resin, etc. Its function is to prevent macromolecular substances from reaching the electrode surface, avoid dry resistance and prevent pollution. The appearance of the fabricated biosensor is shown in Figure 1(b)7.

During the measurement, the biosensor and the reusable reference electrode constitute a measurement circuit, and the electrical signal output by the sensor is processed by the measurement circuit to display the concentration of a substance in the solution. Such as the measurement of glucose, the linear measurement range is 0.5-25mmol/L, the detection limit is up to 55mmol/L, the response time is 25 seconds, and each measurement time is 30-45 seconds. The encapsulated biosensors are stored at 4°C and are valid for 8 to 12 months. Using the basic electrode, the concentration of lead ions in the solution is measured by anodic stripping voltammetry, and the linear measurement range reaches 0.05-100 μg/L.

The utility model can carry out chemical modification on the surface of the basic electrode to form a chemically modified electrode, and can also be coated with various immobilized enzyme films, immobilized microbial films, and biological tissue immobilized films, thereby forming enzyme biosensors, microbial sensors and biological tissues Sensors for the measurement of various substances. The base electrode can be used as an electrochemical detector for the determination of the concentration of heavy metal ions.

This biosensor is suitable for clinical testing, family monitoring, environmental monitoring, health inspection, labor protection, chemical process monitoring, fermentation process control and other fields.

Claims (1)

1. A disposable biosensor, characterized in that a conductive layer, a protective ring, a chemical repair layer, an immobilized bioactive film and an anti-interference film are printed on a sheet metal substrate.

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