JPS6361157A - chemical sensor card - Google Patents

Abstract

PURPOSE:To make a chemical sensor easy to carry and to analyze a specimen on the sampling spot, by incorporating elements such as a solid chemical sensor, for example, an enzyme FET sensor, an amplifying circuit, an operation circuit, a display device, a power source or the like in an IC card. CONSTITUTION:Spots 11 to which a specimen is added, a solar cell 12, a display device 13 and sheet switches 4 are incorporated in an IC card to constitute a chemical sensor. Further, a temp. sensor is mounted in said card to perform the temp. correction of measuring output. As each of the spots 11, one formed by fixing an ion selective response film or an enzyme film to ISEFT or a membrane electrode is used. When one of the sheet switches 14 is pushed and the specimen is added to each spot 11, the interface potential of ISEFT changes and the specimen is analyzed from said potential to display an analytical result on a display device 13. Since various elements such as a solid chemical sensor or the like are incorporated in the IC card to be made portable, environmental analysis and clinical analysis can be performed on the site sampling the specimen.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a portable chemical sensor device used in fields such as environmental analysis and clinical analysis, and which is not limited to any environment.

[Background of the Invention] Chemical sensors have been actively developed in the fields of environmental analysis and clinical analysis due to their simplicity and speed of analysis, their use in the field, and their use in the field of medical examinations and house calls. It's here. Gas sensors, ion sensors, enzyme sensors, immune sensors, etc. have been proposed as chemical sensors.

Generally, chemical sensors are constructed as a combination of a receptor and a transducer. A receptacle is a substance that specifically reacts with or binds to a measurement target, such as a gas adsorption membrane, an ion permeation membrane, an ion exchange membrane, or an enzyme,
Substrate, substrate analog.

Membranes on which biotin, antibodies, antigens, receptacles (in a narrow sense), etc. are immobilized are used. On the other hand, transducers include glass electrodes, metal electrodes (platinum, gold, etc.), thin film gold layer electrodes,
l5FET, photodiode, phototransistor,
Materials such as thermistors, oxygen electrodes, H2O2 electrodes, ammonia electrodes, etc.

They are classified into various types depending on their structure or use. Furthermore, by combining these receptors and transducers, 68 different types of sensors are emitted.
These are used in combination as appropriate depending on the purpose or use.

Here, an enzyme sensor will be described below as a typical example.

Normally, measurements using an enzyme sensor are performed as follows. That is, an enzyme electrode, in which a membrane on which an enzyme is immobilized is attached to an electrode sensitive to the substrate or product of an enzyme reaction, such as a pH electrode, an oxygen electrode, a hydrogen peroxide electrode, or an ammonia electrode, and a reference electrode (silver, A silver chloride electrode or an Amagi electrode) is inserted into the sample solution kept at a constant temperature, and the potential difference between the two electrodes is measured at a potentiometer. Analyzers using enzyme electrodes have already been put into practical use, and relatively small desktop-type devices are commercially available. However, since the electrodes are made of glass, they are easily damaged, and the device is too large to be held in one hand, making it unsuitable for portable use.

Various attempts have been made to eliminate individual shortcomings. With the recent development of semiconductor microfabrication technology, sensors have become ultra-small and durable by using 15FET and 1110 electrodes in transducers, and metal interfaces created by replacing reference electrodes with metal electrodes. The potential is
It has also become clear that compensation can be achieved by combining senna with immobilized enzyme and a sensor without immobilized enzyme or with a sensor in which the enzyme is immobilized and then deactivated, and measuring the differential output.

On the other hand, with the development of ICs, electronic elements have become ultra-miniaturized, and credit card-sized calculators,
Memory cards and the like have been put into practical use.

[Object of the Invention] The present invention has been made in view of the above, and its object is to provide a chemical sensor device that is easy to carry and suitable for outdoor use. Another object of the present invention is to provide a chemical sensor device that does not require a constant temperature device.

Still another object of the present invention is to provide a chemical sensor device capable of measuring the entire surface.

Yet another object of the present invention is to provide a chemical sensor device that can measure multiple items simultaneously.

[Summary of the Invention] The chemical sensor card of the present invention, which has been made to achieve the above object, is characterized in that a solid chemical sensor, an amplifier circuit, an arithmetic circuit, a display, and a power source are integrated into a card-shaped body. It is characterized by being built-in.

The solid state chemical sensor used in the present invention includes l5F
ET, thin film electrode or thermistor with ion selective sensitive membrane, ion selective permeable membrane, ion exchange membrane, or enzyme,
A sensor with a membrane fixed thereon, such as a substrate, antibody, antigen, or receptor, is preferably used, but any sensor that can be solidified and made thin can be incorporated into a sensor card.

For example, in an enzyme FET sensor, a decrease in substrate or an increase in product due to an enzyme reaction changes the interfacial potential of the rsFET, and this change is extracted as an electrical signal. Furthermore, in the antibody FET sensor, changes in interfacial potential due to the formation of a complex between an antibody and an antigen are extracted as an electrical signal. In the chemical sensor explained in the example, the enzyme is added to the frost U.
Although a method of accumulating and solidifying a LB film on a transducer is shown, enzymes can also be immobilized using a chemical bonding method, a physical adsorption method, an entrapment method, or the like.

Various measurement circuits are used as amplifier circuits depending on the type of transducer. The signal amplified by the amplifier circuit is digitized by an A/D converter and a V/F converter, and the measurement results are shown on a display. The chemical sensor output may be displayed as is, but in many cases it is displayed as the concentration of the chemical component using a standard curve and conversion factor stored in memory.

The output of the 15FET and the output of the thin film electrode exhibit temperature dependence. The enzyme reaction rate also shows temperature dependence.

In the present invention, since the temperature sensor can be built into the sensor card, temperature errors can be corrected using correction coefficients stored in advance in the memory.

The display device is not particularly limited, but a liquid crystal display is preferable because its driving voltage and driving current are small. As a power source, thin batteries such as solar cells and lithium batteries are preferably used.

The sensor card configured as described above has an area of 30cd to 1oOci, and an area of I'+7 and 2a+a+ to 1
0M, and further miniaturization is possible by miniaturizing individual modules.

Serum is generally used for chemical analysis of biological components. However, serum separation requires time and centrifugation equipment. In the present invention, by interposing a porous membrane between the sample addition spot of the sensor card and the chemical sensor, these devices become unnecessary and it becomes possible to use a blood sample. In this case, the porous membrane is preferably a hydrophilic membrane such as a cellulose membrane, preferably a membrane having pores of 0.1 μm to 30 μm. Therefore, the sensor card according to the present invention does not require serum separation and can be used for measurement on its entire surface. On the other hand, in the field of environmental analysis, it is also possible to directly add turbid wastewater or the like to the sensor card by selecting an appropriate membrane from among the membranes.

This sensor card can incorporate multiple types of sensors and can simultaneously measure multiple items. Therefore, by using a sensor card that incorporates related items as a set, it becomes possible to properly diagnose the cause of the disease. For example, in the above-mentioned size, up to 7 to 8 types of sensors are incorporated.

[Embodiments of the Invention] The present invention will be further described below with reference to embodiments shown in the drawings.

Embodiment FIG. 1 is an external view of an example of a sensor card according to the present invention. 11 is the spot where the sample is added, 12 is the solar cell, 1
3 is a liquid crystal display circuit star and a sheet switch. If you press the start switch immediately after adding the sample to the sensor card, any value such as the output after a certain period of time, the steady output value, the maximum output value, or the output at maximum tilt will be stored in the sensor card. The measurement results can be managed by transferring the measurement results to an external data processing device through the terminal of the temperature sensor and storing time series data in the external data processing device. The data transmission terminal is not limited to the one using the metal terminal shown in this embodiment, and may use an electromagnetic coupling.

FIG. 2 is an external view of an example of the sensor card according to the present invention. In the figure, 21 to 25 correspond to 11 to 15, respectively. By using this sensor, it is also possible to place the sample addition spot directly into the sample and perform measurements. In the embodiment shown in FIG. 11 and FIG. 2, a sample addition spot is provided for each measurement item, but by miniaturizing the sensor, multiple sensors can be integrated in one spot.
It is also possible to attach a hydrophilic film such as a cellulose acetate film to the sensor surface and spread a sample added to one spot onto multiple sensors by diffusion.

Further, in the embodiments shown in FIGS. 11 and 2, the sensor section is integrated, but it is obvious that the sensor section can be constructed so that only the sensor section can be replaced, or that the number of items can be increased to a single item or more.

FIG. 3 is a diagram showing a schematic diagram of an example of a sensor card according to the present invention. In this figure, 31 is a chemical sensor, 32
33 is a temperature sensor (thermistor), 33 is an amplifier circuit, 34 is a multiplexer, 35 is an arithmetic circuit, 36 is a liquid crystal display circuit, 37 is a switch circuit, and 38 is a power supply.

FIG. 4 shows an example of a chemical sensor used in this card, which is a sensor for measuring urea. 41 is a measurement sensor, 44 is a pseudo reference electrode, and 45 is a comparison sensor. The measurement sensor and the comparison sensor are formed on a silicon substrate 48.
Aragin B with urease adsorbed on the surface of 5FET,
This is an accumulation of LB films. The comparative sensor was further irradiated with ultraviolet light to deactivate the enzyme. The pseudo reference electrode is made by forming an insulating film on a silicon substrate and further depositing gold on it. A commonly used amplifier circuit connected to the 15FET is shown in FIG. 51 and FIG.

FIG. 5 is a constant drain current circuit. In this circuit, the gate voltage is controlled so that the drain current is constant. l
Changes in the interface potential of the 5FET are determined from changes in gate voltage. The output is obtained as the difference between the measurement sensor and the comparison sensor. FIG. 6 shows a constant gate voltage circuit. In this circuit, a change in interface potential is applied to the channel of the rsFET superimposed on the gate voltage, causing a change in the drain current. This circuit converts the train current into a voltage using a current-voltage conversion circuit, and outputs the difference between the measurement sensor and the comparison sensor. FIG. 7 shows an example of a calibration curve for a sensor for measuring urea.

FIG. 8 shows another example of a chemical sensor used in this card, which is a glucose measurement sensor. 81 is a measurement anode, 82 is a reference cathode, and 83 is a comparison anode. Each electrode is mounted on a glass substrate. It is formed by a thin film of vapor-deposited gold.

On the surface of each electrode, an arachidic acid LB film adsorbed with glucose-ol-1-siguse was accumulated. Glucose oxidase immobilized on the surfaces of the reference cathode and comparative anode was inactivated by ultraviolet light to prevent the enzyme from leaking. A commonly used amplifier circuit connected to a thin film electrode sensor is shown in Fig. 91 and Fig. 10.

Figure 9 shows the circuit used in the potentiometric method.
0 is a circuit used in the Amperome 1~S-Schiff method. FIG. 10 shows an example of a calibration curve for a glucose measuring sample.

[Effects of the Invention] According to the present invention, a portable chemical sensor device used in fields such as environmental analysis and m-bed analysis has become possible. Furthermore, according to the present invention, it has become possible to immediately analyze the sample at the site where it was collected, and therefore it has become possible to immediately feed back the analysis results. Furthermore, it has become possible to quickly analyze samples without pretreatment.

[Brief explanation of drawings]

FIG. 1 is an external view of an example of a sensor card of the present invention. FIG. 2 is an external view of another example of the sensor card of the present invention. Figure 3 is a block diagram of the sensor card. Figure 4 is a sensor for measuring urea, and Figure 5 is an example of a constant drain current circuit. Figure 6 is an example of a constant gate voltage circuit 1 Figure 7 is a glucose measurement sensor 0 Figure 8 is a potentiometric measurement circuit 1
FIG. 9 shows a measuring circuit for amperometric method 1. FIG. 10 shows an example of a calibration curve for a sensor for measuring glucose. 11.21: Spot for sample addition, 12.38: Solar cell, 13, 23.36 + liquid crystal display, 14° 24.37
: sheet switch, 31: solid chemical sensor, 32: 4 degree sensor 233: multiplexer. 34: Drawer, 41.51, 61: Measurement sensor. 42.46: l5FET, 43: urease immobilized membrane, 44, 52, 62: l pseudo reference ° electrode, 45°5
3.63: Comparison sensor, 47: Ultraviolet irradiation urease immobilization membrane, 48; Silicon substrate, 81°91.101
: Anode for measurement, 82, 92° 102: Common cathode, 83, 93, 103: Cathode for comparison, 84 Niger glucose oxidase immobilized membrane, 85: Ultraviolet heat DJ glucose oxidase immobilized membrane, 86: Plastic mounted substrate. Patent applicant Toyo Soda Kogyo Co., Ltd. Figure 1 Figure 2 Figure 5 Figure 7 Figure 8 Figure 9

Claims (4)

[Claims] (1) A chemical sensor card comprising a solid-state chemical sensor, an amplifier circuit, an arithmetic circuit, a display, and a power source, each of which is incorporated into an IC card. . (2) The chemical sensor card according to claim 1, wherein a temperature sensor is incorporated, and the output of the solid chemical sensor is temperature-corrected and displayed on a display. (3) The chemical sensor card according to claim 1, which has a serum separation filter, and the added whole blood sample comes into contact with the solid chemical sensor after passing through the serum separation filter. (4) The chemical sensor card according to claim 1, which has a plurality of solid chemical sensors.