JPS6130754A - Electrochemical sensor and inspection apparatus using the same - Google Patents

Abstract

PURPOSE:To eliminate the deformation of a membrane under negative and positive pressure states, in an electrochemical sensor having the conductive boundary surface contacted with a membrane for passing a chemical substance and an electrode in the opposite side of the membrane. CONSTITUTION:A boundary liquid phase 57 having an electrolyte having conductivity fixed thereto is provided in an electrode body 56 and a Pt-electrode 52 is provided to the inside of the body 56 of said liquid phase 57 and the lead wire 51 of the electrode 52 is connected to an opposed electrode. A membrane 53 for passing a chemical substance in a specimen is provided to the opposite side of the electrode 52 of the liquid phase 57 and a porous membrane 54 for protecting from directly applied pressure is provided to the surface thereof and fixed to the body 56 by rolling 55. Further, when the gas in the specimen is measured as the membrane 53, a gas permeable membrane is used and, when the special substance in the specimen is detected by enzymatic reaction, an enzyme membrane is used.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an electrochemical sensor capable of quantifying a chemical substance in a specimen by converting it into an electrical signal, and an inspection device using the electrochemical sensor.

[Background of the invention]

Conventional electrochemical sensors have a thin film on the electrode surface through which chemical substances in the sample pass (for example, a gas permeable membrane when measuring gas components in the sample, an ion permeable membrane when measuring ionic components, and a thin film that allows the chemical substances in the sample to pass through). A conductive boundary phase (mainly an electrolyte solution) that is in contact with this thin film, and an electrode (transducer) that is in contact with this liquid phase on the opposite side of the thin film. The types include a gas sensor (also referred to as a gas electrode) that measures the gas concentration in a specimen, an ion sensor (also referred to as an ion electrode) that measures the ion concentration in a specimen, There are enzyme sensors (also called enzyme electrodes) that measure the concentration of a special substrate through an enzymatic reaction, biosensors that measure the amount of microorganisms in a specimen, and antigen-antibody sensors that measure a special antigen in a specimen using an antibody. These are known (for example, ■Blood Gas P150 to P188, published by Shinko Trading Co., Ltd., Medical Book Publishing Department, published in 1981; ■Ion Electrode and Enzyme Electrode, published in 1981, published by Kodansha Saisen Teifuku Co., Ltd., Publishing Department).

In such an electrochemical sensor, the electrode emits a predetermined electrical signal depending on the type and amount of the chemical substance that has passed through the thin film and exists in the boundary phase between the thin film and the electrode, and the amount of the chemical substance is quantified. Is going.

As an example of the above electrochemical sensor, C0 in a sample
BACKGROUND ART There are gas electrodes for detecting the concentration of gases such as No. 2, and enzyme electrodes for measuring glucose by converting glucose in blood into hydrogen peroxide in blood samples by enzymatic reaction.

In order to perform accurate measurements with the electrochemical sensor described above, it is necessary to accurately match the amount of chemical substances with the electrical signals output from the electrodes.

Therefore, as the electrochemical sensor is used, the composition of the boundary phase that exists between the thin film and the electrode changes, and the amount of chemical substance in the sample no longer corresponds to the electrical signal, so the lifetime of the electrochemical sensor is generally limited. It is provided.

In addition, the thin film is made thin to improve responsiveness, and when using an electrochemical sensor, when the sensor is under positive pressure, the thin film deforms and the thickness of the boundary phase changes depending on the thin film. Change.

Therefore, the amount of chemical substances in the sample and the change in the electrical signal in the boundary phase do not correspond accurately. Further, deformation of the thin film may damage the thin film, further shortening the life of the thin film.

Therefore, in testing equipment that uses the electrochemical sensor described above to measure the amount of chemical substances in a sample while flowing the sample, it is necessary to use atmospheric pressure to prevent direct positive pressure or positive pressure from being applied to the thin film of the electrochemical sensor. The chemical substances in the samples were being measured. However, in such a testing device, since the specimen must flow through the channel to the position where the chemical electrode is present, the specimen is drawn to the measurement site using a pump. Furthermore, if a blockage occurs in a part of the channel, which is likely to occur with a highly viscous sample, the blockage must be removed by applying pressure to the sample in the channel using a pump.

Therefore, the thin film of an electrochemical sensor cannot avoid being under pressurized or negative pressure.

This further shortens the life of the electrochemical sensor, which poses a problem in terms of accuracy of an inspection device using this electrochemical sensor.

[Purpose of the invention]

A first object of the present invention is to provide an electrochemical sensor that is free from deformation of the thin film even when used under positive pressure or pressurized conditions.

A second object of the present invention is to provide an inspection device that can accurately measure the amount of chemical substances in a sample even when using a conventional electrochemical sensor.

[Summary of the invention]

The first invention of the present application includes a thin film that allows the chemical substance in the specimen to pass through either as it is or after being converted into another chemical substance through an enzyme reaction, and a thin film that has electrical conductivity and is in contact with the thin film. An electrochemical sensor comprising: an existing boundary phase; and an electrode that is in contact with the boundary phase on the opposite side of the thin film, passes through the thin film, and outputs an electrical signal according to the amount of the chemical substance present in the boundary phase. In the electrochemical sensor, a porous protective film is provided on the surface of the thin film to prevent the thin film of the electrochemical sensor from being deformed or damaged by pressure, thereby making it possible to accurately measure the total amount of chemical substances in the sample. It is a chemical sensor.

The second invention of the present application includes a flow channel for flowing a sample, a pump for guiding the sample into the flow channel, or for sucking or pushing out the sample in the flow channel when a blockage occurs in the flow channel, and A thin film that changes the chemical substance in its original form or into another chemical substance through an enzyme reaction, etc., and allows the chemical substance to pass through; a boundary phase that has electrical conductivity and exists in contact with the thin film; an electrochemical sensor having an electrode that contacts the boundary phase on the opposite side of the thin film and outputs an electrical signal according to the amount of the chemical substance that passes through the thin film and is present in the boundary phase; and the electrochemical sensor. means for displaying an electrical signal detected by the electrochemistry system, so as to quickly detect a change in pressure such as a blockage occurring in the flow channel, and quickly discover a blockage in the flow channel. This testing device is characterized by its ability to accurately measure the amount of chemical substances in a sample without applying excessive pressure to the thin film of the sensor.

The protective film used in the electrochemical sensor of the first invention of the present application is generally a woven fabric and is made of polymeric fibers such as polyester, nylon, polyglobulene, and carbon fiber, and has a thickness of 30 mm.
A net-like metal thin film having the above-mentioned thickness and pore size and made of a chemically inert substance such as platinum and woven with a pore diameter of 10 to 300 μm or less is preferably used. The above-mentioned net-like plastic or metal thin film is preferably woven in a cross-like manner from thread-like fibers with a wire diameter of 10 to 150 μIn, and the pore size of the woven fabric is 60 to 300 mesh 1 inch as mesh size NO. is preferably used. In addition to the above, polyethylene, Teflon, etc. can also be used as the polymer resin that forms the fibers.

Further, it is desirable that the above-mentioned protective film is not affected by chemical components in the specimen and is not likely to have any effect on the specimen. For example, when the specimen is blood, it does not cause blood coagulation. Basically, any chemically inert substance can be used. In this sense, chemically inert metals such as platinum can also be used.

[Embodiments of the invention]

Next, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a configuration diagram showing an embodiment of an electrochemical sensor according to the first invention of the present application.

In the figure, there is a boundary liquid phase 57 in which a conductive electrolyte liquid is fixed inside the electrode body 56 of the vapor chemical sensor, and a space is suspended inside the body 56 of this liquid phase 57 in contact with the liquid phase 57. A PT electrode 52 is mainly provided.

The electrode 2 has a conductive wire 51 for guiding an electric signal from the electrode 52.
Although not shown in the drawings, this conducting wire 51 is connected to a counter electrode. The boundary liquid phase 57
On the opposite side of the electrode 52, a thin film 53 is provided in contact with the boundary liquid phase 57, which allows the chemical substance in the specimen to pass through.

A porous material (a net-like plastic woven fabric) 54 is provided on the surface of the thin film 53 to protect the thin film from pressure directly applied to the thin film 53. This porous material 54 is fixed to a body 56 by a low link 55.

Since the porous material 54 is provided in this embodiment,
The pressure generated on the specimen is not directly applied to the thin film 53.

Note that the thin film 53 is a scum-permeable membrane when measuring a gas in a specimen, and an enzyme membrane is used when a special substance in a specimen is detected by an enzyme reaction.

Further, in this embodiment, a liquid phase having electrical conductivity is used as the boundary liquid phase. In addition, a solid phase can also be used. Further, the composition of the liquid phase is determined depending on the type of chemical substance to be detected, and for example, in an enzyme sensor for measuring the amount of glucose in blood, it is an IMOI solution of KCI.

FIG. 2 is a configuration diagram showing an embodiment in which the electrochemical sensor according to the first invention of the present application is used in an inspection device.

In this example, a case will be described in which blood is used as a specimen.

The blood test apparatus according to the present embodiment consists of three main flow path systems. One of them is PH2゜PO2, PC
A flow path system 22 consisting of a gas electrode section for measuring blood gas such as O2, two of which are a flow path system 23 consisting of an ion electrode section for measuring ion concentrations of Na, CL, Ca, etc. Three of them are a flow path system 24 consisting of an enzyme electrode section that measures the concentration of glucose, urea nitrogen, etc. by utilizing an enzyme reaction.

A squeeze bomb 1, 28, 29 is provided in each of the flow path systems, and waste liquid is discharged from the flow path outlet 2. Furthermore, a sampling nozzle 20 is provided in each flow path.

A cut pulp 17 to which a standard solution suction nozzle 18 is connected is provided in the middle of the flow path 22, and further includes a liquid sensor 3, a comparison electrode 9, a PH electrode 4, a PO2 electrode 5, a PCO
Two electrodes 7 are provided.

A cut valve 25 to which the standard solution ion suction nozzle 19 and the buffer solution suction nozzle 21 are connected is provided in the middle of the flow path 23, and in the middle of the flow path 23, a liquid sensor 8, a reference electrode 26, and an Na electrode are provided. 10, K electrode 11, Ct electrode 12,
A liquid sensor 16 , a reference electrode 27 , a glucose electrode 14 , and a urea nitrogen electrode 15 are provided in the middle of the Ca electrode 13 in the flow path 24 .

Here, in the ion electrode section 23, the imine permeable membrane of the general ion electrode is generally thick, about 0.2 to 0.4 trrm.゜5 K5+/m" (DO pressure: can easily withstand pressure removal. However, in the waste electrode section 22 and the enzyme electrode section 24, the thickness of the sensitive membrane is such that the response time is within 1 to 2 minutes. 10-30 to suppress
An extremely thin polymer membrane of micrometers is used. Therefore, it is difficult for such a thin film to maintain a stable state under the positive pressure generated by the above-mentioned squeeze bombs 1, 29 or under pressure, and especially under pressure, the gas permeable membrane and sensitive membrane must be in close contact with each other. may become separated from the electrochemical device, making measurement impossible.

Next, the operation of this embodiment will be explained.

The sampling nozzle 20 is driven by the squeeze pump 1, 28, 29 provided in each of the channels 22, 23, 24.
A blood sample is sampled from. At this time, the cut pulp 17.25 has a blood sample in each of the channels 22, 23, 24.
The pulp is controlled so that it flows smoothly.

When the blood sample has spread to the various electrodes provided in each of the channels 22, 23, 24, the squeeze pump 1,
28. Stop 29. This is for each flow path system 22, 23.2
This is due to the fact that if the electrodes provided at No. 4 were to perform measurements under pressurized or negative pressure conditions, it would not be possible to make measurements that accurately correspond to the amount of the sample chemical substance. Next, the gas concentration, electrolyte concentration, and substrate concentration such as glucose urea in the blood is measured according to the characteristics of the electrodes provided in each channel system. This measurement is carried out using reference electrodes 9 provided in each flow path system 22, 23, 24.
, 26, 27, and the potentials generated at each electrode are calculated, and the concentration of each component is converted according to this difference.

After the above measurements are completed, the cut pulp 17°25 is
The standard solution gas from the standard solution gas pulp 18 flows into the channel 22, the standard solution ions from the standard solution ion pulp 19 flows into the channel 23, and the buffer solution from the buffer solution pulp 21 flows into the channel 24. Controlled squeeze pump 1,
Driven to 28.29.

Then, by driving the squeeze pumps 1, 28, 29, the blood that had been present in each channel 22, 23, 24 is discharged as waste fluid, and each standard solution is replaced by each channel 22, 23, 24.
24, and the amount of chemical substance in the standard solution is measured at the electrode section in each channel. The reason why the standard solution is measured in this manner is to obtain accurate measurements even if the influence of output instability that may occur at each electrode on the measurement is eliminated.

When the measurement of the above standard solutions is completed, the coral bomb 1.28
．． 29 and control of the cut pulp 17.25, each flow path 22, 23.24 is replaced with the next blood sample.

By the way, if something like blood tends to aggregate and cause clogging in a narrow channel, it is necessary to discover the clogging in order to perform accurate measurements.

The clogging can be detected by abnormal measurements at each electrode, but it can be detected quickly by providing pressure sensors in each channel 22, 23, 24 to detect the pressure within the channel. . When a blockage is discovered, the blockage is removed by driving the squeeze pumps 1, 28 and 29.

As described above, this embodiment has the following unique effects.

In other words, in conventional testing devices that measure the concentration of special substrates such as gas components, electrolyte components, curcose, and urea in blood using electrochemical sensors, in order to improve responsiveness, Gas permeable membranes, ion permeable membranes, and enzyme membranes are thin. Furthermore, since the flow path leading the sample to the measuring section is narrow, the flow path resistance increases, blood clogs are likely to occur, and electrolytes and the next sample cannot be exchanged quickly. If you forcefully increase the driving force of the squeeze bomb to increase the flow of the sample in the channel, the electrochemical sensor will easily deteriorate. Therefore, it has not been possible to respond to tests that require quick and urgent testing in hospitals, but the blood test apparatus of this embodiment solves the above problems.

In addition, by installing a pressure sensor in the above-mentioned inspection equipment, it is possible to quickly discover blockages in the flow path, and by applying pressure correction to the measured value according to the pressure detected by the pressure sensor. This makes it possible for the electric sensor to perform continuous measurements while flowing the sample into the flow path under pressurized or negative pressure conditions, rather than under atmospheric pressure conditions.

FIG. 3 is a configuration diagram showing an embodiment of the inspection device according to the third invention of the present application.

This example will be explained using blood as in the example shown in FIG. 2, but the electrochemical sensor uses a conventional sensitive membrane without a protective film.

This embodiment differs from the embodiment shown in FIG. 2 in that pressure sensors 30, 31, and 32 are necessarily used in each channel system. Therefore, in this embodiment, the parts designated by the same reference numerals as those in the embodiment of FIG. 2 have the same structure and operation.

This embodiment has the following unique effects.

In other words, it is necessary to drive the coral bomb when blood clogs occur in the flow path or when replacing the sample or standard solution in the flow path with another sample or standard solution.

At this time, it is possible to prevent an unnecessarily large pressure from being applied to the surface of the gas permeable membrane, ion permeable membrane, enzyme membrane, etc. of the electrochemical sensor by detecting the channel pressure with a pressure sensor. Therefore, by preventing the electrochemical sensor from deteriorating more than expected, it is possible to obtain an inspection device with high measurement accuracy.

Further, by providing the pressure sensors 30, 31, and 32, continuous measurement of the specimen can be performed while the specimen is flowing through the flow path, similar to the embodiment shown in FIG. Furthermore, the pressure sensor constantly detects the pressure in each flow path.
If the pressure in the flow path becomes negative, an alarm is generated and the Sogoki pump 1 is immediately stopped, thereby preventing damage to the membranes of the gas and enzyme electrodes.

FIG. 4 is a configuration diagram of a pressure sensor used in the embodiments of FIGS. 2 and 3. FIG.

When the sample is blood, a semiconductor pressure sensor such as a strain gauge is preferably used as a pressure sensor that measures pressure changes in a flow path caused by changes in the viscosity or the like of blood. In addition, by detecting changes in the liquid level position in a glass tube made by winding a capillary-shaped glass tube in a U shape or in a spiral shape, it is possible to know changes in pressure within the flow path. Specifically, as shown in Fig. 4, a capillary-shaped glass tube or plastic tube 44 is connected to the sample flow path by a cross tube, and at this time, the position of the liquid level entering the capillary tube is detected using a photocoupler or the like. Then, the internal pressure of the flow path can be known.

Note that 31 indicates the sampling channel outlet, and 46 indicates the sampling channel inlet.

The desirable characteristics of this pressure sensor are that it can detect fluctuations in fluid pressure before the gas permeable membrane or enzyme membrane separates from the electrochemical device such as the PT electrode or hydrogen peroxide electrode, and the Since it is necessary to stop rotation and issue an alarm to the operator, etc., responsiveness to pressure fluctuations is also important. Suitable pressure sensors for this purpose include not only semiconductor strain gauges but also liquid column type pressure sensors.

〔Effect of the invention〕

As described above, according to the present invention, since a protective film is provided on the surface of the thin film of an electrochemical sensor, the stability of the thin film can be improved, and as a result, the life of the electrochemical sensor can be extended. be able to.

Next, by using such an electrochemical sensor, it is possible to improve the measurement accuracy of a test device that measures the amount of chemical substances in a sample.

Furthermore, by providing a pressure sensor in an inspection device that measures the amount of chemical substances in a specimen using a conventional thin-film electrochemical sensor without a protective film, it is possible to improve the measurement accuracy of the inspection device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of an electrochemical sensor according to the first invention of the present application, and FIG. 2 is a block diagram showing an embodiment of an inspection device using the electrochemical sensor according to the first invention of the present application. , FIG. 3 is a block diagram showing an embodiment of an inspection device according to the second invention of the present application, and FIG. 4 is a block diagram showing an embodiment of a pressure sensor. 1.28.29... Coral pump, 22... Gas electrode part flow path, 23... Ion electrode part flow path, 24... Enzyme electrode part flow path, 30, 31. 32... Pressure sensor ,
52... Electrode, 53... Thin film, 54... Protective film,
56...Body.

Claims (1)

[Claims] 1. A thin film that allows the chemical substance in the sample to pass through either as it is or after changing it into another chemical substance; a boundary phase that is in contact with the thin film and has electrical conductivity; An electrochemical sensor comprising: an electrode that is in contact with the boundary phase on the opposite side of the thin film and that passes through the thin film and outputs an electrical signal according to the amount of the chemical substance present in the boundary phase; An electrochemical sensor characterized by having a porous protective film. 2. The electrochemical sensor according to claim 1, wherein the protective film is at least one of a thin film of an inert metal and a thin film of high quality fiber. 3. An electrochemical sensor as set forth in claim 1, wherein the inert metal is platinum. 4. A flow channel for flowing the sample, a pump that sucks or pushes out the sample in the flow channel to flow the sample into the flow channel, and a chemical substance in the sample as it is or converted into another chemical substance. a thin film through which the chemical substance passes; a boundary phase in contact with the thin film and having electrical conductivity; An inspection device comprising: an electrochemical sensor having an electrode that outputs an electrical signal according to the amount of a substance; and means for displaying the electrical signal detected by the electrochemical sensor.