JPH0518890A - Ion sensor, and method and device for measuring ion concentration using the sensor - Google Patents

Abstract

PURPOSE:To detect measurement object ion selectively and at high speed by layering Langmuir-Blodgett(LB) film having amphiphilic organic matter and ion sensing material on the surface of transparent inductor putting a metal film in between. CONSTITUTION:On one side of a transparent base plate 2, an LB film is layered putting a metal thin film 3 in between and by holding this film 4 in a cell frame 7 provided with a sample injection tube 5 and exhaust tube 6 so as to contact to a measured sample, a flow cell is constituted. A specific ion concentration in the sample is measured. As for the metal constituting the thin film 3, Ag and Au are preferable as they have a large real part of complex dielectric constant compared with the imaginary part. For the film 4 constitution material, a amphiphilic substance is used generaly. Therefore, the film 4 having the function of selecting ion is produced, for example, by adding ion sensing material to a amphiphilic substance or synthesizing a new ion sensing material with an amphiphilic property. By this, a film sensing selectively to various anion and cation can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion sensor for measuring a specific ion concentration in a solution and an ion concentration measuring method and apparatus using the ion sensor.

[0002]

2. Description of the Related Art Conventionally, measurement of ion concentration in a solution has been carried out by a flame light method, an ion selective electrode method, etc., but recently, measurement by an optical method has also begun to be proposed. For example, Japanese Unexamined Patent Publication (Kokai) No. 3-122553 discloses an optical sensor for detecting a change in absorbance or fluorescence emission amount of a polyion complex LB film to which an ionophore and a voltage-sensitive dye are added, and APPLIED OPTICS / Vol.27. ,
No.6 / 15March 1988. p.1160 to 1163 discloses a technique for measuring alcohol concentration in water by a surface plasmon resonance method.

[0003]

However, in the optical sensor disclosed in Japanese Patent Laid-Open No. 122553/1993, the change in absorbance is about 10 ^{-4 and the} change in fluorescence emission amount is about 10 ^-2 to 10 ^-3. Since it is extremely small, it is difficult to perform high-sensitivity photometry, and there are various points to be improved such as small S / N. In addition, the technique disclosed in the above-mentioned document merely provides a metal thin film on one surface of the optical prism and measures the alcohol concentration by the surface plasmon resonance method. It cannot be applied to the measurement of the specific ion concentration of the test solution.

The present invention has been made to solve various problems caused by the above-mentioned optical method, and the first purpose thereof is to appropriately configure the ion to be measured selectively and with high sensitivity. It is to provide an ion sensor. A second object of the present invention is to provide a novel ion concentration measuring method which can selectively measure ions to be measured with high accuracy by using the above ion sensor. Further, a third object of the present invention is to provide an ion concentration measuring device appropriately configured so that the above-mentioned ion concentration measuring method can be implemented easily, in a small size and at a low cost.

[0005]

In order to achieve the above first object, in the ion sensor of the present invention, at least a metal thin film is provided on the surface of a dielectric transparent to light of a specific wavelength. LB having an amphipathic organic compound and an ion-sensing substance that is selectively sensitive to a specific ion
It is constructed by stacking films.

In order to achieve the second object, in the ion concentration measuring method of the present invention, an amphipathic organic substance is formed on the surface of a dielectric material transparent to light of a specific wavelength at least through a metal thin film. Using an ion sensor formed by stacking an LB film having a compound and an ion-sensitive substance that selectively reacts with a specific ion, a measurement sample is brought into contact with the LB film of the ion sensor, and the LB film is interposed via the dielectric. P-polarized monochromatic light is incident on the metal thin film under the condition of total reflection to induce surface plasmon resonance, and the specific ion concentration in the measurement sample is measured based on the reflected light.

Further, in order to achieve the above third object,
In the ion concentration measuring apparatus of the present invention, a light source that emits monochromatic light, and an ion-sensitive substance that selectively reacts with an amphipathic organic compound and a specific ion through at least a metal thin film on one surface of a transparent substrate. An ion sensor formed by laminating the LB film, an optical prism provided on the other surface of the transparent substrate of the ion sensor, a condenser lens arranged between the light source and the optical prism, and reflection on the metal thin film. A photoelectric conversion element for receiving light through the optical prism, wherein a monochromatic light from the light source is passed through the condensing lens and the optical prism in a state where a measurement sample is in contact with the LB film of the ion sensor. A P-polarized light is incident on the thin film under the condition of total reflection to induce surface plasmon resonance, and the reflected light is received through the optical prism. Configured to measure specific ion concentration in the measurement sample on the basis of the force.

[0008]

1 is a sectional view showing a first embodiment of the ion sensor of the present invention. In this ion sensor 1, an LB film 4 having at least an amphipathic organic compound and an ion-sensitive substance selectively sensitive to a specific ion is laminated on one surface of a transparent substrate 2 through a metal thin film 3 to form a surface. The specific ion concentration in the measurement sample is measured by the plasmon resonance method. In this embodiment, the ion sensor 1 is placed in a cell frame 7 provided with an injection pipe 5 and a discharge pipe 6 for a measurement sample,
The LB film 4 is held in contact with the measurement sample to form a flow cell.

The metal forming the metal thin film 3 is a "surface" Vo.
As described in p.289 to 304 of l.20 No.6 (1982), Ag, Au, Cu, Zn, Al, and K are desirable because the real part of the complex permittivity is large and negative. From the size relationship, Ag and Au are particularly preferable, and Pd, Ni and Fe are not desirable. Further, the metal thin film 3 can be composed of an alloy composition, but when Pd is mixed with Ag, the surface plasmon resonance disappears, so that the use of this alloy is not preferable. Further, the metal thin film 3 is formed on the transparent substrate 2
On the transparent substrate 2 in order to improve the adhesion to
The Cr film may be formed to be extremely thin and an Au film or the like may be formed thereon to form a multilayer structure.

The LB film 4 can be formed, for example, by Masakazu Okada et al., "Molecular Design Technology," Science Forum Co., Ltd., P. 89.
In general, an amphipathic substance is used as a constituent substance as described in JP-A No. 61-254634 and JP-A No. 3-122553.
As disclosed in Japanese Patent Laid-Open Publication No. JP-A-2004-242242, a polyion complex substance composed of an ionic amphipathic compound and an ionic polymer having an opposite charge is used to maintain the charge of the LB film at a neutral level. It is also possible to facilitate the approach of ionic components to shorten the reaction time and stabilize the LB film.
In this embodiment, the LB film 4 is provided with an ion selection function. Such an LB film 4 is prepared by, for example, adding an ion-sensitive substance to an amphipathic substance, or an ion-sensitive substance so as to be amphiphilic. Can be prepared by a method of newly synthesizing

Here, as the ion-sensitive substance, valinomycin, which is well known as a K ⁺ ion-sensitive substance, and the crown ethers described in Electrochemistry 53, No. 12 (1985) p.942-946, Cryptand, Donald
Spherands described in J. Cram et al. J. Am. Chem. Soc. 1988, 110, p571 to 577 can be used, which forms the LB film 4 selectively sensitive to various cations. can do. In addition, Quaternary ammonium salts and orthophenanthroline derivative metal compounds described in Nobuhiko Ishibashi Bessaku Kagaku Kogyo, Vol.28 No.6 (1984) p.324-329, and Wihelm Simon et al, Anal.Chem.1984,56. , p.5
The neutral carriers described in 35 to 538 can be used, whereby the LB film 4 selectively sensitive to various anions can be formed.

When the ion sensor 1 is manufactured as described above and the sample is brought into contact with the LB film 4, a film potential is generated corresponding to the specific ion concentration, and at that time, the film is formed in the film thickness direction. It is possible to detect the surface plasmon resonance condition that changes depending on the size of the electric dipole. In the ion sensor 1, it is desirable that the film thickness of the LB film 4 be such that the evanescent light effectively reaches. For this purpose, the combined film thickness of the metal thin film 3 and the LB film 4 is not more than twice the excitation wavelength, The thickness is preferably equal to or less than the excitation wavelength.

FIG. 2 is a sectional view showing a second embodiment of the ion sensor of the present invention. This ion sensor 11 is the same as the ion sensor 1 shown in FIG.
And a dielectric thin film 12 is provided between and. The dielectric thin film 12 is preferably transparent and is formed as thin as possible in the range of several Å to several thousand Å. For example, imides represented by polyimide, amides such as nylon, arachidic acid, octadecanol, etc., which form a dense film, diic acid, ω-tricosenoic acid, etc., by the LB method which is a method of forming an ultra-thin film. It is preferable to form a film such as a molecule having a polymerizable group of
It can also be constituted by an oxide film or a nitride film of O ₂ , Si ₃ N ₄ , Ta ₂ O _5, or the like.

When the dielectric thin film 12 is provided between the metal thin film 3 and the LB film 4 as in this embodiment, Cu, K, Al, Zn, etc., which are easily sampled as the metal thin film 3, are added. When used, it can be effectively protected from the sample.

Since the LB film 4 is made of an amphipathic substance, it is necessary to control the properties of the substrate. In addition to physical methods such as plasma treatment, the LB method for forming a strong film using the substance shown in FIG. 2 is also effective. For example, by lowering the transparent substrate 2 on which the hydrophobic metal thin film 3 is formed in the water tank of the LB film manufacturing apparatus, one layer of LB film of arachidic acid is laminated on the surface of the metal thin film 3 to form the dielectric thin film 12. At the same time, the surface of the dielectric thin film 12 is kept hydrophilic by holding the substrate 2 in water, and then the molecular film on the water surface is exchanged to raise the substrate 2 to make the surface of the dielectric thin film 12 have an ion selective function. The LB film 4 is formed by laminating any LB film having In this way, the properties of the surface of the dielectric thin film 12 serving as the substrate can be controlled.

FIG. 3 is a sectional view showing a third embodiment of the ion sensor of the present invention. This ion sensor 21 is the same as the ion sensor 1 shown in FIG. 1, except that an optical prism 23 is provided on the other surface of the transparent substrate 2 via a refractive index adjusting oil 22. As described above, by providing the optical prism 23, it becomes possible to easily enter the P-polarized monochromatic light for inducing the surface plasmon resonance into the metal thin film 3 under the condition of total reflection. Note that such a configuration can be effectively applied to the ion sensor 11 shown in FIG.

In another embodiment of the ion sensor of the present invention, in the ion sensor shown in FIGS. 1 and 2, the transparent substrate 2 is replaced by the optical prism 23 shown in FIG. The LB film 4 is solid-phased on one surface via the metal thin film 3, or the LB film 4 is solid-phased via the metal thin film 3 and the dielectric thin film 12. According to this structure, the number of parts can be reduced, and the cost can be reduced easily and easily.

In each of the above embodiments, the LB film 4 is composed of an amphipathic organic compound and an ion-sensitive substance which is selectively sensitive to specific ions. In other embodiments of the present invention, the LB film 4 is composed of an amphiphilic substance. Organic compound, an ion-sensitive substance that selectively reacts with a specific ion, and a voltage-sensitive dye. As described above, when the voltage-sensitive dye is added to the LB film 4, the dielectric constant of the voltage-sensitive dye changes according to the membrane potential generated by the ion sensitivity, and the dielectric constant is also detected by the surface plasmon resonance method. Become. Therefore, since the voltage-sensitive dye acts to sensitize the ion sensitivity, higher sensitivity measurement becomes possible.

The potential-sensitive dye is roughly classified into a substance whose fluorescence intensity changes according to a potential difference and a substance whose absorbance changes according to the potential difference. When the fluorescent dye is formed by directly contacting the metal thin film 3. , It may not emit fluorescent light. Therefore, in this case, preferably, the dielectric thin film 12 is interposed between the metal thin film 3 and the LB film 4 as shown in FIG. 2, and the dielectric thin film 12 protects the metal thin film 3 from the sample. At the same time, the voltage-sensitive dye is prevented from coming into direct contact with the metal thin film 3 to prevent quenching of fluorescence.

Next, an ion concentration measuring method using the ion sensor according to the present invention will be described. FIG. 4 shows an example of the configuration of an ion concentration measuring device for carrying out the ion concentration measuring method of the present invention. In this example, FIG.
Using the ion sensor 21 shown in FIG. 1, monochromatic light from the laser light source 31 is made to enter P-polarized light into the metal thin film 3 through the condenser lens 32 and the optical prism 23 under the condition of total reflection, and the reflected light is reflected by the optical prism 23 and the cylindrical The light is received by the photodiode array 34 arranged on the focal plane through the lens 33. The cylindrical lens 33 and the photodiode array 34 are arranged so that the reflected light incident on the photodiode array 34 has an angular spectrum. It should be noted that the cylindrical lens 33 may be omitted in practical use.

In the above structure, when the monochromatic light from the laser light source 31 is made incident on the ion sensor 21 through the condenser lens 32 while the measurement sample is flowing through the injection tube 5 and the discharge tube 6, specific ions in the measurement sample are obtained. Surface plasmon resonance is induced depending on the concentration, and an angular spectrum of reflected light is generated on the photodiode array 34. Here, since each element of the photodiode array 34 corresponds to the reflection angle of light, the element corresponding to the strongest position of the dark line generated by the surface plasmon resonance is detected from the output of the photodiode array 34, and the element is detected. The reflection angle of the absorption peak is detected from the position, and the specific ion concentration in the measurement sample is measured based on the reflection angle. When an LB film having an ion selection function to which a voltage-sensitive dye is added is used as the ion sensor, the wavelength of the monochromatic light from the laser light source 31 is matched with the excitation wavelength of the voltage-sensitive dye.

Experimental examples will be described below. <Experimental Example 1> A cleaned slide glass having a refractive index of 1.523 was used as a transparent substrate, and a metal thin film was formed on one surface of the slide glass by a vacuum evaporation method to a thickness of about 1 nm and a thickness of about 40 nm.
A gold film of nm was laminated in the order of glass / Cr / Au. afterwards,
The surface of the Au film was hydrophilized by irradiation with O ₂ plasma, and then LB film having ion selection function, valinomycin (10 mol%) and octadecyl rhodamine B (C ₁₈ RB; 1 mol%) having K ⁺ ion selection function. An arachidic acid film containing and was further formed by the LB method. The LB film is
Toluene was used as the developing solvent and the specific resistance was 17.0 as the sewage phase.
Ion-exchanged water of MΩ · cm or more was used and the surface pressure was kept at 23 mN / m to form by the vertical dipping method. An ion sensor is manufactured as described above, and an optical prism is provided on the other surface of the slide glass via a refractive index adjusting oil,
Surface plasmon resonance was observed with the configuration shown in FIG.

FIG. 5 shows an angular distribution curve of reflectance obtained from the output of the photodiode array when pure water as a measurement sample is brought into contact with the LB film of the above-mentioned ion sensor, and FIG. 6 similarly shows the LB film. 10 ^-4 mol / l KC as a measurement sample
l It shows an angle distribution curve of reflectance when a solution is brought into contact with the vertical axis showing reflectance and the horizontal axis showing reflection angle. From FIG. 5 and FIG. 6, it can be seen that when the measurement sample is changed, the reflection angle of the absorption peak moves to the larger side.

FIG. 7 shows the result of an experiment in which pure water and measurement samples having different K ⁺ ion concentrations were alternately measured. The vertical axis represents the element number of the photodiode array and the horizontal axis represents time.
From the results of this experiment, the measured sample was purified from pure water to 10 ^-4 mol / l KCl.
It can be seen that the element numbers of the absorption peaks in pure water are almost the same and are reversible even when the pure water is replaced with pure water. If the sample to be measured is 10 ^-1 mol / l KCl, 10 ^-4
It can be seen that the reflection angle of the absorption peak is larger than that in the case of mol / l KCl. From the above, K ^{+ of} the measurement sample
It was found that the reflection angle of the absorption peak increased with increasing ion concentration depending on the ion concentration, whereby the K ⁺ ion concentration can be measured with high sensitivity.

<Experimental Example 2> A transparent substrate having a refractive index of 1.523
Using the washed slide glass of No. 1, a chromium film having a thickness of about 1 nm and a gold film having a thickness of about 45 nm were laminated in this order as a metal thin film on one surface thereof by a vacuum deposition method in the order of glass / Cr / Au. After that, the surface of the Au film is subjected to hydrophilic treatment by Ar plasma irradiation, and then C
_A polyion complex membrane composed of polycarboxymethyl cellulose-dimethyldioctadecyl ammonium containing ₁₈ RB (2 mol%) was further formed by the LB method. The LB film has a specific resistance of 17.0 MΩ as the sewage phase.
Using an aqueous solution of polycarboxymethyl cellulose dissolved in ion-exchanged water of 10 cm or more at a concentration of 10 ^-3 % by weight, dimethyldioctadecyl ammonium bromide (2C ₁₈ N2C ₁ Br ₁ ) containing C ₁₈ RB (1 mol%) was used on the water surface. ) Was dissolved in chloroform, developed, left for 5 minutes and then compressed,
It was formed by the vertical dipping method while maintaining the surface pressure of 25 mN / m. The LB film responds selectively to Cl ⁻ ions. An ion sensor was produced as described above, an optical prism was provided on the other surface of the slide glass via a refractive index adjusting oil, and the surface plasmon resonance of the configuration shown in FIG. I made an observation.

FIG. 8 shows experimental results obtained by measuring pure water and measurement samples having different Cl ⁻ ion concentrations, where the vertical axis represents the element number of the photodiode array and the horizontal axis represents time. From this experimental result, it can be seen that when the measurement sample is changed from pure water to 10 ⁻⁴ mol / l KCl, and further to 10 ⁻³ mol / l KCl, the measured values become smaller in order contrary to the experimental example 1. From this, it was found that the reflection angle of the absorption peak became smaller as the concentration of Cl ⁻ ion in the measurement sample increased, whereby the Cl ⁻ ion concentration could be measured with high sensitivity.

<Experimental Example 3> A transparent substrate having a refractive index of 1.523
On the one surface of the washed slide glass of No. 3, a silver vapor deposition film having a thickness of about 55 nm was formed as a metal thin film. Next, in order to make the surface of the silver vapor deposition film hydrophilic, a arachidic acid film is formed as a transparent dielectric thin film by the LB method, and then an LB film having an ion selection function is formed on the dielectric thin film. 15 mol% of bis [(12 crown 4) methyl] methyl dodecyl malonate (commonly known as bis 12 crown 4) as a Na ⁺ ion sensitizer and 5 as a voltage-sensitive dye
-(N octadecanol) aminofluorescein 1 m
It was further formed with octadecanoic acid containing ol%. In addition,
Chloroform was used as the developing solvent, and ion-exchanged water having a specific resistance of 17.0 MΩ · cm or more was used as the sewage phase. The film was formed by the vertical immersion method, the arachidic acid LB film was kept at a surface pressure of 25 mN / m, and the octadecanoic acid LB film was kept at a surface pressure.
I kept it at 23mN / m. An ion sensor was produced as described above, an optical prism was provided on the other surface of the slide glass via a refractive index adjusting oil, and the surface plasmon resonance of the configuration shown in FIG. I made an observation.

FIG. 9 shows the results of an experiment in which pure water and measurement samples having different Na ⁺ ion concentrations were alternately measured. The vertical axis and the horizontal axis were the element numbers of the photodiode array and the same as in FIGS. Represents time. From this experimental result, it was found that even if the measurement sample was changed from pure water to 10 ^-5 mol / l NaCl, and then to pure water, the element numbers of the absorption peaks in pure water were almost the same, and they were reversible changes. Recognize. In addition, the measurement sample is 10 ^-4 mol /
It can be seen that in the case of l NaCl, the reflection angle of the absorption peak is larger than that in the case of 10 ^-5 mol / l NaCl. From the above, it was found that the higher the concentration of Na ⁺ ion in the measurement sample, the larger the reflection angle of the absorption peak, and thus the Na ⁺ ion concentration can be measured with high sensitivity. When silver is used as the metal thin film, if oxygen plasma treatment is applied to the surface to make it hydrophilic, the surface becomes black and adversely affects hydrophilicity.
It was confirmed that by forming one layer of the Z-type LB film as described above, the surface can be effectively changed to a hydrophilic surface, and the ion concentration can be stably measured.

In the above-mentioned ion concentration measuring apparatus, a photodiode array is used, and the element corresponding to the strongest position of the dark line generated by the surface plasmon resonance is detected from the output to detect the reflection angle of the absorption peak, Although the specific ion concentration in the measurement sample is measured based on the reflection angle, one photoelectric conversion element is used instead of the photodiode array, and the specific ion concentration in the measurement sample is measured based on the output. It can also be configured as follows. Further, in the above-mentioned embodiment, the ion sensor is of the flow cell type, but it may be of the dip type.

[0030]

As described above, according to the ion sensor of the present invention, the amphiphilic organic compound and the specific ion are selected on the surface of the dielectric transparent to the light of the specific wavelength through at least the metal thin film. Since the LB film having the ion-sensitive substance that is sensitive to light is laminated, the film thickness of the LB film can be controlled to about several nm, and therefore the size and cost can be reduced, and the ions to be measured for anions and cations can be measured by the surface plasmon resonance method. Can be selectively detected with high sensitivity.

Further, according to the ion concentration measuring method of the present invention, P-polarized monochromatic light is made incident on the metal thin film under the condition of total reflection while the measurement sample is in contact with the LB film using the above-mentioned ion sensor. Then, the surface plasmon resonance is induced, and the specific ion concentration in the measurement sample is measured based on the reflected light, so that the measurement target ion can be selectively measured with high accuracy.

Further, according to the ion concentration measuring apparatus of the present invention, the monochromatic light from the light source is incident on the metal thin film of the ion sensor as P-polarized light under the condition of total reflection through the condenser lens and the optical prism to cause surface plasmon resonance. Is induced and the reflected light is received by the photoelectric conversion element through the optical prism to measure the specific ion concentration in the measurement sample, so that the configuration can be simplified, and the size and cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of an ion sensor of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the same.

FIG. 3 is a sectional view showing a third embodiment of the same.

FIG. 4 is a diagram showing a configuration of an example of an ion concentration measuring device of the present invention.

FIG. 5 is a diagram showing an angular distribution of reflectance in pure water by surface plasmon resonance measured by the ion concentration measuring method of the present invention.

FIG. 6 is a diagram showing an angular distribution of reflectance of a 10 ⁻⁴ mol / l KCl solution.

FIG. 7 is a diagram showing the measurement results of K ⁺ ion concentration by the ion concentration measuring method of the present invention.

FIG. 8 is a diagram showing a measurement result of Cl ⁻ ion concentration in the same manner.

FIG. 9 is a diagram similarly showing the measurement results of Na ⁺ ion concentration.

[Explanation of symbols]

1 Ion sensor 2 transparent substrate 3 metal thin film 4 LB film 5 injection tubes 6 discharge pipe 7 cell frame 11 Ion sensor 12 Dielectric thin film 21 Ion sensor 22 Refractive index adjusting oil 23 Optical prism 31 Laser light source 32 condenser lens 33 Cylindrical lens 34 photodiode array

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[Procedure amendment]

[Submission date] September 25, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 13

[Correction method] Added

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Here, as the ion-sensitive substance, valinomycin, which is well known as a K ⁺ ion-sensitive substance, and the crown ethers described in Electrochemistry 53, No. 12 (1985) p.942-946, Cryptand, Donald
Spherands described in J. Cram et al. J. Am. Chem. Soc. 1988, 110, p571 to 577 can be used, which forms the LB film 4 selectively sensitive to various cations. can do. Nobuhiko Ishibashi, Kagaku Kogyo, Vol.28 No.6 (1984) p.324-329, quaternary ammonium salts, orthophenanthroline derivative metal compounds, and Wilhel m Simon et al, Anal. Chem. 1984. , 56,
The neutral carrier described in p.535 to 538 can be used, whereby the LB film 4 selectively sensitive to various anions can be formed.

[Procedure 3]

[Document name to be corrected] Drawing

[Correction target item name] Figure 8

[Correction method] Change

[Correction content]

[Figure 8]

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Taiji Nagata             2-43 Hatagaya, Shibuya-ku, Tokyo Ori             Inside Npus Optical Industry Co., Ltd. (72) Inventor Masatsugu Shimomura             2-24-48-103 Nakamachi, Koganei-shi, Tokyo (72) Inventor Ichiro Yamaguchi             2-1 Hirosawa, Wako-shi, Saitama RIKEN (72) Inventor Takayuki Okamoto             2-1 Hirosawa, Wako-shi, Saitama RIKEN

Claims (12)

[Claims] 1. A Langmuir-Blodgett film having, on a surface of a dielectric material transparent to light of a specific wavelength, an amphipathic organic compound and an ion-sensitive substance that selectively reacts with a specific ion through at least a metal thin film. An ion sensor formed by stacking (LB film). 2. The ion sensor according to claim 1, wherein a voltage-sensitive dye is added to the LB film. 3. The ion sensor according to claim 1, wherein the dielectric is composed of an optical prism, and the metal thin film and the LB film are directly immobilized on one surface of the optical prism. 4. The metal thin film having a multi-layered structure of different metals.
The ion sensor described. 5. A transparent substrate is interposed between the optical prism and the metal thin film.
The ion sensor described. 6. The ion sensor according to claim 1, wherein a hydrophobic or hydrophilic dielectric thin film is interposed between the metal thin film and the LB film. 7. An LB film having an amphipathic organic compound and an ion-sensitive substance selectively sensitive to a specific ion is laminated on at least a metal thin film on the surface of a dielectric transparent to a light of a specific wavelength. Surface plasmon resonance by injecting P-polarized monochromatic light on the metal thin film through the dielectric under the condition of total reflection in a state where the measurement sample is in contact with the LB film of the ion sensor. Is induced, and the specific ion concentration in the measurement sample is measured based on the reflected light. 8. The ion concentration measuring method according to claim 7, wherein the reflected light is received by a photoelectric conversion element, and the specific ion concentration in the measurement sample is measured based on the received light output. 9. The reflected light is received by a photoelectric conversion element array, the reflection angle of an absorption peak due to the surface plasmon resonance is detected from the received light output, and the identification in the measurement sample is performed based on the detected reflection angle. The ion concentration measuring method according to claim 7, wherein the ion concentration is measured. 10. A light source that emits monochromatic light, and an LB film having an ion-sensitizing substance that selectively reacts with an amphipathic organic compound and specific ions at least through a metal thin film is laminated on one surface of a transparent substrate. Ion sensor consisting of
An optical prism provided on the other surface of the transparent substrate of the ion sensor, a condenser lens disposed between the light source and the optical prism, and a photoelectric conversion element that receives light reflected by the metal thin film through the optical prism. In the state where the LB film of the ion sensor is in contact with the measurement sample, monochromatic light from the light source is incident on the metal thin film as P-polarized light under the condition of total reflection through the condenser lens and the optical prism. An ion concentration measuring device configured to induce surface plasmon resonance and to measure a specific ion concentration in the measurement sample based on an output of the photoelectric conversion element that receives the reflected light through the optical prism. . 11. The voltage sensitive dye is added to the LB film constituting the ion sensor.
The ion concentration measuring device described. 12. The ion concentration measuring device according to claim 10, wherein the wavelength of the monochromatic light emitted from the light source is matched with the excitation wavelength of the voltage-sensitive dye.