JPH0743342B2 - Lithium ion sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention measures a lithium ion sensor, and in particular, the concentration of lithium ion in the circulatory system in the body, which is changed by the administration of lithium carbonate used for the treatment of manic depression. The present invention relates to a lithium ion sensor that does.

[Prior Art] With regard to the pathophysiology of manic depression, depression occurs due to reserpine that depletes brain monoamines, and treatment of depression (antidepressant) has the property of enhancing the action of monoamines. From this, the monoamine hypothesis was born that depression is a condition in which noradrenaline or serotonin is decreased alone or together, and conversely, when these are increased, it is in a manic state. However, solid blood, urine, bone marrow fluid, and brain tissue analyzes of patients have not yet provided conclusive evidence to support this hypothesis. Therefore, lithium carbonate is often used for the treatment of manic state, and it is expected to suppress the actions of noradrenaline and serotonin in the brain.

To know the lithium ion concentration in the circulatory system in the body due to this lithium carbonate and its change are indispensable for the research on the cause of mania and the treatment method. However, there is currently no lithium ion sensor that has a fast response and high accuracy. Further, there is a need for a sensor that is safe for continuous measurement in the circulatory system or the body for a long time and has stable characteristics.

[Problems to be Solved by the Invention] Japanese Patent Application Laid-Open No. 61-266952 assigned to the applicant of the present invention discloses that a conductive carbon surface is coated with a quinone-hydroquinone type or amine-quinoid type redox film, and A potassium ion sensor whose surface is coated with a potassium ion carrier film is disclosed.

In addition, in Japanese Patent Application No. 61-15344 assigned to the present applicant (Japanese Patent Laid-Open No. 62-254050), the surface of the gate insulating film of MOSFET or its surface is coated with a conductive layer such as conductive carbon. An ion-selective FET sensor whose surface is coated with a redox functional layer, and whose surface is further coated with various ion-selective layers,
Japanese Patent Application No. 61-275250 (Japanese Patent Application Laid-Open No. 63-131056 discloses that a carbon thin film is coated on a semiconductor substrate, a gate insulating film surface of a MOSFET is covered with an organic thin film, and an FET film is further formed on the surface. FET electrodes coated with a hydrogen ion selective layer have been reported.

However, the structure of a lithium ion sensor that has a fast response speed, good accuracy, and is safe and stable for long-term continuous measurement, that is, a suitable lithium ion sensitive layer and this lithium ion sensitive layer are electrically or physically bonded No mention is made of a structure in which the property is kept good and the surface of the gate insulating film of the FET or the surface of the conductive material is covered.

INDUSTRIAL APPLICABILITY The present invention provides a lithium ion sensor that has a fast response and a high measurement accuracy.

Further, the present invention provides a lithium ion sensor which is safe in the body and can be stably measured for a long time.

In addition, a lithium ion sensor that can be stored for a long time is provided.

[Means for Solving the Problem] In order to solve this problem, a lithium ion sensor of the present invention includes a FET, and a redox functional layer that covers the gate insulating film of the FET and exhibits a redox function. Coating the redox functional layer with dibenzyl-14-crown-4 or dioxaheptyl-dodecyl-14-crown-4 or diethoxyphosphorioxyethyl-dodecyl-14-crown-4, and / or its derivatives. And a lithium ion sensitive layer selectively sensitive to lithium ions.

Further, a conductive substrate having at least a surface made of a conductive material, a redox functional layer for covering the surface of the conductive substrate and exhibiting a redox function, and a redox functional layer coated to form a dibenzyl-14-crown. -4 or dioxaheptyl-
Dodecyl-14-crown-4 or diethoxyphosphorioxyethyl-dodecyl-14-crown-4, and / or
Or a polyvinyl chloride layer containing a derivative thereof, and a lithium ion sensitive layer selectively sensitive to lithium ions.

[Example] As an FET used in the present invention, there is a MOSFET.

In particular, as the MOSFET used in the present invention,
Any material can be used as long as it can be used for ISFET and has a gate insulating layer (hereinafter sometimes referred to as a gate insulating film) [Matsuo, Esashi "Electrical Chemistry and Industrial Physical Chemistry" 50 , 64 (1982)], eg having a Si-SiO ₂ gate insulating layer on a silicon or sapphire substrate
An FET formed is used, and an isolation gate type is preferably used. The one using a silicon substrate is versatile because it is relatively inexpensive, and the one using a sapphire substrate is superior in terms of functionality, such as easy multi-processing, easy insulation, and easy miniaturization. .

The MOSFET can be manufactured by using the conventional planar technology, ion implantation technology, or the like. By forming an insulating film made of Si ₃ N ₄ etc. on the surface of the gate insulating layer of the MOSFET by using the CVD method (chemical vapor deposition method) or the sputtering method, it is possible to further improve the insulating performance of the gate section. it can.

The conductive substrate used in the ion sensor of the present invention is, for example, basal plane pyrolytic graphite (hereinafter referred to as BPG).
,), Conductive carbon materials such as glassy carbon;
Examples thereof include metals such as gold, platinum, copper, palladium, nickel, and iron, particularly noble metals or those whose surfaces are coated with a semiconductor such as iridium oxide or tin oxide. Above all,
A conductive carbon material is preferable, and BPG is particularly preferable.

Since the conductive base makes the ion sensor small,
A stick-shaped one is used, and an redox functional layer having a redox function is applied to the outer peripheral surface or 1 to ² mm ² of the outer peripheral surface and the tip surface. If the area is smaller than this, the membrane resistance will exceed 50 MΩ, which is not preferable, and if it is larger, the ion sensor will not be small. The stick may be cylindrical, prismatic, etc.,
From the viewpoint of moldability and film adherence, a cylindrical shape with a rounded tip is particularly preferable.

Conventionally, BPG has mainly been used as a basal surface as an electrode surface. However, the present inventor has found that the edge surface of the BPG can be effectively used, and accordingly, even if the BPG is used, a stick-shaped electrode can be formed. BPG is particularly excellent in terms of stability of sensor operation. For example, in the case of a cylindrical shape, the BPG stick has a diameter of 0.1 to 2 mm from the viewpoint of strength.
Is preferred.

Further, as the conductive substrate, one based on a metal or semiconductor substrate, or one combined with a separation gate type field effect transistor (FET), coated with a carbon film containing a carbon material, or printed Various materials are used depending on the application, such as those in which the conductive wire of the substrate is coated with a carbon material. A composite sensor can also be created by using a printed circuit board or the like.

The redox functional layer has a property that a constant potential can be generated by a redox reaction in a gate insulating film of a FET or a conductive substrate formed by depositing it on the surface, and in the present invention, it is particularly preferable. It is preferable that the potential does not fluctuate due to the partial pressure of oxygen gas. Examples of such a redox functional layer include an organic compound film or a polymer film capable of performing a quinone-hydroquinone type redox reaction, an organic compound film or a polymer capable of performing an amine-quinoid type redox reaction. Suitable examples include membranes and conductive substances such as poly (pyrrole) and poly (thienylene).

Here, the quinone-hydroquinone type redox reaction means, for example, in the case of a polymer, a reaction represented by the following reaction formula.

(In the formula, R ₁ and R ₂ represent, for example, a compound having an aromatic-containing structure.) The amine-quinoid type redox reaction is, for example, in the case of a polymer similar to the above, for example, the following reaction Refers to something expressed by a formula.

(In the formula, R ₃ and R ₄ represent, for example, a compound having an aromatic-containing structure) Examples of the compound capable of forming the layer having a redox function include the following compounds (a) to (d): Can be mentioned.

(In the formula, Ar ₁ is an aromatic nucleus, each R ₅ is a substituent, m ₂ is 1 to Ar ₁
The effective aromatic valence number, n ₂ represents 0 to Ar ₁ effective valence number -1).

The aromatic nucleus of Ar ₁ is a monocyclic ring such as a benzene nucleus, anthracene nucleus, pyrene nucleus, chrysene nucleus,
It may be a polycyclic nucleus such as a perylene nucleus or a coronene nucleus, and may be a heterocyclic bone nucleus as well as a benzene skeleton nucleus. Examples of the substituent R ₅ include an alkyl group such as a methyl group, an aryl group such as a phenyl group, and a halogen atom.

Specifically, for example, dimethylphenol, phenol, hydroxypyridine, o- or m-benzyl alcohol, o-, m- or p-hydroxybenzaldehyde, o- or m-hydroxyacetophenone, o.
-, M- or p-hydroxypropiophenone, o
-, M- or p-hydroxybenzophenone, o-,
m- or p-carboxyphenol, diphenylphenol, 2-methyl-8-hydroxyquinoline, 5-hydroxy-1,4-naphthoquinone, 4- (p-hydroxyphenyl) 2-butanone, 1,5-dihydroxy- 1,2,3,4
-Tetrahydronaphthalene, bisphenol A, salicylanilide, 5-hydroxyquinoline, 8-hydroxyquinoline, 1,8-dihydroxyanthraquinone, 5-hydroxy-1,4-naphthoquinone and the like can be mentioned.

(B) The following formula (In the formula, Ar ₂ is an aromatic nucleus, each R ₆ is a substituent, m ₃ is 1 to Ar ₂
N ₃ is 0 to Ar ₂ −1.
Represents an amino aromatic compound.

As the aromatic nucleus of Ar ₂ and the substituent R ₆ , those similar to Ar ₁ and the substituent R ₅ in the compound (a) are used. Specific examples of the amino aromatic compound include aniline and 1,2-
Diaminobenzene, aminopyrene, diaminopyrene, aminochrysene, diaminochrysene, 1-aminophenanthrene, 9-aminophenanthrene, 9,10-diaminophenanthrene, 1-aminoanthraquinone, p-phenoxyaniline, o -Phenylenediamine, p-chloroaniline, 3,5-dichloroaniline, 2,4,6-trichloroaniline, N-methylaniline, N-phenyl-p-phenylenediamine and the like.

(C) Quinones such as 1,6-pyrenequinone, 1,2,5,8-tetrahydroxyalizarin, phenanthrenequinone, 1-aminoanthraquinone, purpurine, 1-amino-4-hydroxyanthraquinone and anthralphine.

Among these compounds, especially 2,6-xylenol, 1-
Aminopyrene is preferred.

(D) Pyrrole and its derivatives (for example, N-methylpyrrole), thiophene and its derivatives (for example, methylthiophene) and the like.

Furthermore, examples of the compound capable of forming the redox function according to the present invention include poly (N-methylaniline) [Oonuki, Matsuda, Koyama, Journal of Chemical Society of Japan, 1801-1809 (1984)], poly (2,6).
-Dimethyl-1,4-phenylene ether), poly (o-
(Phenylenediamine), poly (phenol), polyxylenol; polymers of pyrazoloquinone vinyl monomers,
(A) to (d) such as quinone-based vinyl polymer polycondensation compounds such as polymers of isoalloxazine-based vinyl monomers
An organic compound containing a compound of (a) to (d), a low-polymerization degree high molecular compound (oligomer) of the compound of (a) to (d), or
The thing which has the said redox reactivity, such as what fixed (a)-(d) to the high molecular compound of a polyvinyl compound and a polyamide compound, is mentioned. In the present specification,
The term polymer includes both homopolymers and interpolymers such as copolymers.

In the present invention, in order to deposit the compound capable of forming the above redox functional layer on the gate insulating film of the FET or on the conductive substrate, an amino aromatic compound, a hydroxy aromatic compound or the like is electrolytically oxidized. Polymer or electron beam irradiation synthesized on the gate insulating film of FET or conductive substrate such as conductive carbon or noble metal by the chemical method or electrolytic deposition method,
A method in which a polymer synthesized by application of light, heat, etc. is dissolved in a solvent and applied or dipped on the FET gate insulating film or conductive substrate by reacting in a gas phase under vacuum. Direct deposition on the gate insulating film of FET or conductive substrate, deposition, direct irradiation on the gate insulating film of FET or conductive substrate by irradiation of light, heat, radiation, etc. be able to. Among these methods, the electrolytic oxidation polymerization method is particularly preferable. In the electrolytic oxidative polymerization method, an aminoaromatic compound, a hydroxyaromatic compound, etc. are electrolytically oxidatively polymerized in the presence of a suitable supporting electrolyte in a solvent to form a polymer layer on the gate insulating film of FET or the surface of a conductive substrate. It is carried out by being coated.

As the solvent, for example, acetonitrile, water, dimethylformamide, dimethyl sulfoxide, propylene carbonate methanol, etc. are used.

Examples of the supporting electrolyte include sodium perchlorate,
Suitable examples include sulfuric acid, disodium sulfate, phosphoric acid, boric acid, potassium tetrafluorophosphate, and quaternary ammonium salt.

The thickness of the redox functional layer is 0.01 μm to 1.0 mm, especially 0.1 μm.
It is preferable that the thickness is m to 0.1 mm. When the thickness is less than 0.01 μm, the effect of the present invention is not sufficiently exerted, and 1.
Making the thickness larger than 0 mm is not preferable for downsizing the sensor.

The redox functional layer used in the present invention can be used by impregnating it with an electrolyte. Examples of the electrolyte include phosphoric acid, dipotassium hydrogen phosphate, sodium perchlorate, sulfuric acid, tetrafluoroborate, and tetraphenylborate. In order to impregnate the redox functional layer with the electrolyte, it is convenient to immerse the redox functional layer in the electrolyte solution after the conductive substrate is coated.

More preferably, in order to prevent the transfer of the lithium ion sensitive layer to the plasticizer and enhance the stability of the sensor, the polymerization reaction is initiated by starting from a dimer or more instead of starting the electrolytic reaction from the monomer. It is possible to obtain a redox functional layer that is dense and has high solvent durability.

Such a dimer or higher multimer is obtained by polymerizing a multimer of a hydroxy compound or an amino compound. However, R ₁₁ and R ₁₂ represent OH or NH ₂ .

Or However, R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ represent OH and / or NH ₂ .

Or However, R ₁₁ and R ₁₂ represent OH or NH ₂ , What can be represented by is good.

In particular, o, o'-biphenol polymer and p, p'-biphenol polymer are preferable.

Next, as the lithium ion sensitive layer 4, dibenzyl-14
-Polyvinyl chloride film containing crown-4 and / or its derivatives, or dioxaheptyl-dodecyl-14
A polyvinyl chloride layer containing crown-4 or diethoxyphosphorioxyethyl-dodecyl-14-crown-4 and / or its derivatives is used.

In the following examples, using basal plane pyrrolytic graphite ((BPG: Union Carbite Co., Ltd.) as a conductive substrate, an electrolytic poly (p, p'-biphenol) polymer layer on this surface, The surface was covered with a polyvinyl chloride layer containing dibenzyl-14-crown-4, which is a lithium ion sensitive layer, and this BPG electrode was connected to the gate terminal of the MOSFET to prepare a lithium ion sensor. A lithium ion sensor was also prepared in which the electrolytic poly (p, p'-biphenol) polymer layer was not coated and the lithium ion sensitive layer was directly coated.

<Example> An example of film coating on a conductive carbon electrode is shown.

FIG. 1 shows a structural schematic view of the lithium ion sensor of this example. Incidentally, the dimensions are not taken into consideration in FIG.

A cylinder 1 with a diameter of 1 mm and a length of 3 mm is cut out (0.2 cm ² ) from a plate of basal plane proliferating graphite (BPC: Union Carbide), and a lead wire 3 (0.1 mmφ uremet is attached to the bottom of one of them). After being bonded with a conductive adhesive 2 (Amicon: C-850-6), it is inserted into a Teflon tube 6 (inner diameter 1.3 mm), and an insulating adhesive 7 (ThreeBond: TB2067). ), The BPG electrode insulated was produced.

Using this conductive BPG electrode as the working electrode, a saturated sodium chloride calomel electrode (SSCE) as the reference electrode, and a platinum mesh as the counter electrode, a redox functional layer was formed by electrolytic polymerization reaction under the following electrolytic oxidation conditions. Then, a p, p'-biphenol polymer film 5 was prepared.

(Electrolytic oxidation reaction conditions) Electrolyte solution: 0.05M p, p'-biphenol 0.2M sodium perchlorate solvent Acetonitrile solution Electrolysis temperature: 23 ℃ Electrolysis condition: -0.2 to +1.5 volts (vs SSCE), sweep speed 50
The electrolytic reaction was performed for 30 minutes by sweeping 27 times at mV / sec.

Figure 6 (a) shows a cyclic voltammogram of the electrolytic reaction.
Shown in.

In Fig. 6 (b), the poly (p, p'-biphenol) film thickness is 1
The response when the pH was changed in a 0.2 M sodium perchlorate solution at 0 μm and the sweep was performed at 200 mV / s is shown.

Then, this poly (p, p'-biphenol) polymer film 5
The lithium ion sensitive layer 4 was dated under the following conditions. The film thickness was 500 μm.

(Lithium ion sensitive layer composition) Dibenzyl-14-crown-4 (6,6-dibenzyl-1,
4,, 8,11-Tetraoxacyclotetradecane) 1.1
Parts by weight Au-nitrophenyl octyl ether 70.2 parts by weight potassium tetrakis (p-chlorophenyl) borate (K-TCPB) 0.7 parts by weight polyvinyl chloride (PVC) 28.0 parts by weight THF solution 3 ml The other end is connected to the gate of MOSFET8, and a lithium ion sensitive field effect transistor (below
Li-ISFET) was created. This is called a PBP / LSM coated sensor.

<Comparative Example> Example Li-ISFET was prepared in which the poly (p, p'-biphenol) polymer film 5 was not coated and a lithium ion sensitive layer having the same composition as in Example was directly coated. This is called an LSM coated sensor.

<Experimental Example 1> The response of the Li-ISFET made in the Examples and Comparative Examples was 150 mM.
In the NaCl solution, the concentration of Li was changed from 1.86 mM to 3.00 mM and tested.

Results are shown in FIG. In the example, 90% response is 10 seconds, and in the comparative example, 90% response is 2 to 3 seconds, both of which are sufficient as the response speed.

<Experimental Example 2> The relationship between the Li ⁺ ion concentration and the output voltage of the Li-ISFETs produced in Examples and Comparative Examples was kept constant at 150 mM NaCl, and pLi was changed from -5.2 at room temperature 25 ° C in a nitrogen atmosphere. I changed it to -1.9 and tested it.

Results are shown in FIG. The results showed that pLi showed a linearity in the range of 1.9 to 2.7, and the gradient at this time was 52 mV / pLi in both cases. Since the Li ⁺ ion concentration related to people with manic depression is around 10 ^-3 M, it is possible to measure in the linear part, and accurate measurement results can be expected.

<Experimental Example 3> Selection coefficient ▲ K ^Pot of sodium- or potassium-ion of Li-ISFET prepared in the examples and comparative examples
_{Li · Na} ▼ and ▲ K ^Pot _{Li · k} ▼ were measured.

The result is that ▲ K ^Pot _Li.Na ▼ is 3.3 × 10 ^-10 , ▲ K ^Pot _{Li ・ k} ▼
It was 6.2 × 10 ^-3 . It is considered to be less than sodium and potassium ions for other ions.

<Experimental Example 4> The effect of dissolved oxygen gas in the Li-ISFETs produced in Examples and Comparative Examples was examined by injecting O ₂ gas and N ₂ gas alternately into a 150 mM NaCl solution (pH 5.55 ± 0.03) containing 1 mM LiCl. Tested.

Results are shown in FIG. From the figure, it can be seen that the Li-ISFET coated with the poly (p, p'-biphenol) polymer film of the example is less affected by oxygen gas.

<Experimental Example 5> Li in a 150 mM NaCl solution of Li-ISFETs of Examples and Comparative Examples.
The change of the slope with time when the ion concentration was increased was tested. During these experiments, the electrode part was 150 mM NaCl in 1 mM Li
It was stored in an aqueous solution containing Cl.

Results are shown in FIG. In terms of change over time, poly (p, p′−
Those coated with a biphenol) polymer film showed sufficiently stable characteristics. The same effect was obtained even when a derivative thereof was used instead of dibenzyl-14-crown-4.

As described above, the lithium ion sensor of this embodiment can accurately detect and measure the lithium concentration in the body.
Also, the influence of other ions such as sodium ions and potassium ions is small.

In addition, the thickness can be made much finer than that of hair, so that it can be inserted into a living body without pain.

In addition, it is not affected by oxygen gas and can be used stably for more than one month.

Moreover, since it is a solid type sensor, it can be sterilized by heating steam and is easy to handle.

In addition, since the lithium ion sensitive layer is an organic thin film, it is unlikely to be affected by blood coagulation in the living body, and measures for that are easy.

Incidentally, the structure of the lithium sensor prepared in this example shows a suitable example, and as described at the beginning of the section of the examples of the present specification, the gate insulating film of the FET is directly coated. It is apparent that the same effects as those of the present embodiment can be achieved by using the materials other than those described above, also using the conductive substrate of the other examples, and the redox functional layer and the lithium ion sensitive layer. .

EFFECTS OF THE INVENTION The present invention can provide a lithium ion sensor that has a fast response and a high measurement accuracy.

Further, it is possible to provide a lithium ion sensor which is safe in the body and can be stably measured for a long time.

Further, it is possible to provide a lithium ion sensor that can be stored for a long time.

More specifically, the lithium concentration in the living body can be accurately detected and measured. Also, the influence of other ions such as sodium ions and potassium ions is small.

In addition, the thickness can be made much finer than that of hair, so that it can be inserted into a living body without pain.

In addition, it is not affected by oxygen gas and can be used stably for more than one month.

Moreover, since it is a solid type sensor, it can be sterilized and is easy to handle.

In addition, since the lithium ion sensitive layer is an organic thin film, it is unlikely to be affected by blood coagulation in the living body, and measures for that are easy.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of the lithium ion sensor of this embodiment, FIG. 2 is a diagram showing the measurement of the response speed of the lithium ion sensor of this embodiment, and FIG. 3 is of the lithium ion sensor of this embodiment. FIG. 4 is a diagram showing the lithium concentration vs. output potential, FIG. 4 is a diagram showing the effect of oxygen gas on the lithium ion sensor of this embodiment, and FIG. 5 is a diagram showing the change over time of the lithium ion sensor of this embodiment. (A) is a diagram showing a cyclic voltammogram, and FIG. 6 (b) is a diagram showing a potential response of a poly (p, p'-biphenol) film. In the figure, 1 ... BPG, 2 ... conductive adhesive, 3 ... lead wire, 4 ... lithium ion sensitive layer, 5 ... poly (p, p '
-Biphenol) polymer film, 6 ... Teflon tube,
7 ... Insulating adhesive, 8 ... MOSFET.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G01N 27/30 331 A 331 J

Claims (15)

[Claims] 1. A FET, a redox functional layer that exhibits a redox function that covers the gate insulating film of the FET, and a redox functional layer that covers the FET, and comprises dibenzyl-14-crown-4- or dioxalate. Lithium ion-sensitive, comprising a polyvinyl chloride layer containing heptyl-dodecyl-14-crown-4 or diethoxyphosphorioxyethyl-dodecyl-14-crown-4, and / or its derivatives, and selectively sensitive to lithium ions A lithium ion sensor comprising: a layer. 2. The lithium ion sensor according to claim 1, wherein the FET is a MOSFET. 3. The redox functional layer is obtained by polymerizing a multimer of a hydroxy compound or an amino compound, and particularly has the following structure. However, R ₁₁ and R ₁₂ represent OH or NH ₂ . Or However, R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ represent OH and / or NH ₂ . Or However, R ₁₁ and R ₁₂ represent OH or NH ₂ , The lithium ion sensor according to claim 1, wherein the lithium ion sensor is selected from those represented by: 4. The lithium ion sensor according to claim 3, wherein the redox functional layer is selected from an o, o'-biphenol polymer and a p, p'-biphenol polymer. 5. The lithium ion sensor according to claim 1, wherein the redox functional layer is selected from the group of substances that perform a quinone-hydroquinone type redox reaction. 6. The lithium ion sensor according to claim 1, wherein the redox functional layer is selected from the group of substances that perform an amine-quinoid type redox reaction. 7. The lithium ion sensor according to claim 1, wherein the redox functional layer is selected from the group of conductive substances such as poly (pyrrole) and poly (thienylene). 8. A conductive substrate, at least the surface of which is made of a conductive material, a redox functional layer for exhibiting a redox function for coating the surface of the conductive substrate, and a dibenzyl-functional coating for coating the redox functional layer. 14-crown-4 or dioxaheptyl-dodecyl-14-crown-4 or diethoxyphosphorioxyethyl-dodecyl-14-crown-4, and / or a derivative thereof comprising a polyvinyl chloride layer containing a lithium ion. A lithium ion sensor comprising a lithium ion sensitive layer that is selectively sensitive. 9. The conductive substrate comprises a metal, a semiconductor substrate as a base coated with a carbon film containing a carbon material, or an isolation gate type field effect transistor (FE).
9. The lithium ion sensor according to claim 8, wherein the separation gate extended from the gate surface with a conductive material in T) is coated with a carbon film containing a carbon material. 10. The lithium ion sensor according to claim 8, wherein the conductive substrate is a conductive carbon material. 11. The redox functional layer is obtained by polymerizing a multimer of a hydroxy compound or an amino compound, and particularly has the following structure: However, R ₁ and R ₂ represent OH or NH ₂ . Or However, R ₁ , R ₂ , R ₃ and R ₄ represent OH and / or NH ₂ . Or However, R ₁ and R ₂ represent OH or NH ₂ , The lithium ion sensor according to claim 8, wherein the lithium ion sensor is selected from those represented by: 12. The lithium ion sensor according to claim 11, wherein the redox functional layer is selected from an o, o'-biphenol polymer and a p, p'-biphenol polymer. 13. The lithium ion sensor according to claim 8, wherein the redox functional layer is selected from the group of substances that perform a quinone-hydroquinone type redox reaction. 14. The lithium ion sensor according to claim 8, wherein the redox functional layer is selected from the group of substances that perform an amine-quinoid type redox reaction. 15. The redox functional layer comprises poly (pyrrole),
9. The lithium ion sensor according to claim 8, wherein the lithium ion sensor is selected from the group of conductive materials such as poly (thienylene).