JPS63265153A - Ion carrier film and ion sensor provided with said ion carrier film - Google Patents

Abstract

PURPOSE:To obtain an ion carrier film, whose mutual stability with an electrolytic polymerization film is enhanced, by using a plasticizer, which is hard to dissolve in solution and has high mobility of ions in the ion carrier film. CONSTITUTION:An ion carrier film 6, which is sensitive to specified ions, is formed with polyvinyl chloride, which is plasticized with a plasticizer. At least one plasticizer is selected from phthalate based plasticizer, maleate based plasticizer, adipate based plasticizer and carbonate based plasticizer. As the phthalate based plasticizer, di-2-ethylhexyl phthalate (DOP), dioctyl maleate (DOM), dioctyl adipate (DOA) and the like are used. Thus the ion carrier film, whose mutual stability with an electrolytic polymerization film is enhanced, is obtained.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to an ion carrier membrane that exhibits ion selectivity in ion sensors, ion selective FET sensors (TSFET), etc., and an ion carrier membrane equipped with the same. The present invention relates to an ion sensor.

[Prior art] Polymer membranes in liquid film electrodes such as ion sensors that use polymer membranes as a substitute for glass membranes: In ion carrier membranes,
Regarding the effect of plasticizer in the film composition, W, Simon (W,
Simon et al. have described the electrical conductivity of membrane solutions (plasticizers) (a group of low-volatility hydrophobic liquids that are compatible with polyvinyl chloride and do not have a proton-friendly reaction: Water-immisci).
ble 1quid of low vapor-p
Ressure, compatible with
PV(:, n.

functional group which
can undergo protonati-
on reaction) improves the selectivity of monovalent cations of the same size (see ``Ion Reaction in Biomedicine'' of the International Research Group by W. Simon
Enzyme Electrode”: Ion Enzyme Electro
des in Biology & Medicine
int, Workshop pp 22-37 (1
976)).

As a result, o-NPOE (o-nitrophenyl-〇-octyl ether: .-nitrophenyl
-n-octylether ε24 (20°C)) is used as a plasticizer, and is used in the Na+ sensor and K3 sensor. Then, DO with a large lipophilic/hydrophilic partition coefficient
It has been reported that 3 (dioctyl sebacate) is the best for ion-selective electrodes (Analytical Chemistry: Anal, Chem
istry 52 (4) 692-700 (198
0)). However, when the ion carrier membrane is in a solid state, this idea does not hold true, and mutual stability between the membrane and the electrolytically polymerized membrane becomes important.

[Problems to be Solved by the Invention] The present invention uses a plasticizer that is difficult to dissolve in a solution and has ion mobility in the ion carrier film, thereby reducing mutual interaction between the electropolymerized film and the electropolymerized film. An ion carrier membrane with improved stability and an ion sensor equipped with the same are provided.

[Means for Solving the Problem] As a means for solving this problem, the ion carrier membrane of the present invention is made of polyvinyl chloride made plasticized with a plasticizer, and is made of polyvinyl chloride that is sensitive to predetermined ions. a carrier film, wherein the plasticizer is a phthalate plasticizer;
It is selected from at least one of maleate ester plasticizers, adipate ester plasticizers, and carboxylic ester plasticizers.

Further, the ion sensor of the present invention includes a conductive substrate, a redox functional layer that exhibits a redox function and coats the conductive base, and an ion carrier film that coats the redox functional layer. The carrier film is an ion carrier film made of polyvinyl chloride plasticized with a plasticizer and sensitive to predetermined ions, and the plasticizer is a phthalate ester plasticizer, a maleate ester plasticizer, or an adipate ester plasticizer. The plasticizer is selected from at least one of a plasticizer and a carboxylic acid ester plasticizer.

The ion sensor of the present invention also includes a gate insulating layer of an FET, a conductive layer covering the gate insulating layer, a redox functional layer covering the conductive layer exhibiting a redox function, and the redox functional layer. an ion carrier film that is sensitive to predetermined ions and is made of polyvinyl chloride plasticized with a plasticizer, and the ion carrier film is an ion carrier film that is sensitive to predetermined ions, and the ion carrier film is made of polyvinyl chloride that has been plasticized with a plasticizer, and the ion carrier film is an ion carrier film that is sensitive to a predetermined ion. The plasticizer is selected from at least one of a maleic acid ester plasticizer, an adipate ester plasticizer, and a carboxylic acid ester plasticizer.

[Function] With this configuration, by using such a plasticizer that is difficult to dissolve in a solution and has ion mobility in the ion carrier membrane, the ion carrier membrane can maintain mutual stability with the electropolymerized membrane. Increase.

[Example] <Example 1> The N electrode shown in FIG. 1 was created by the following procedure. Basalplane pyrolytic graphite (BPG)
(Manufactured by UCC) Cylindrical object 1 with a diameter of 1.56 mm width from a plate
Cut out one side and apply conductive adhesive 2 (Amico
C-850-13) made by n company, connect the silver wire as lead wire 7, and connect the outer periphery with heat shrink tube 3 or BPCI
The gap between the two was insulated with urethane adhesive 4. The BPG substrate prepared in this way was used as a working electrode, a reference electrode (saturated sodium chloride calomel electrode 25SCE), and a counter electrode (platinum wire mesh).
An electrolytic reaction was carried out using the three electrodes in a cell under the electrolytic conditions shown below to form a redox functional layer 5 on the surface of the BPG substrate.

Electrolyte night: 0.2M NaC10
40,5M 2.6-xyletoulacetonitrile
In-solution electrolysis reaction conditions = θ ~ 1.5 volts (vs. 5SCE) 3 sweeps (sweep rate 50 mV/S) Constant potential electrolysis was performed at 1.5 volts (vs. 5SCE) for 10 minutes.

The redox functional layer prepared as described above has a dark red color. After thoroughly washing with water and drying, a coating film was formed using a hydrogen ion carrier solution film 6 as an ion carrier film by a dipping method.

Composition of hydrogen ion carrier solution: Tridodecinogenine
15.65 (mg/mJ1) Potassium tetrakis(p-chlorophenyl)borate 1.5
65 (mg/+nQ) Di-2-ethylhexyl phthalate ester 162.8 (mg/+
++Q ) (DOP) Polyvinyl chloride (pn 1050)
81.25 (mg/m sentence) Tetrahydrofuran (THF) N6fi) 10
ml Dipping conditions: Dipping speed: 10 cm/min Number of operations: 15 times Carrier film thickness: Approximately 0.7 mm Experimental Example 1> Electrolytic redox cloth 5 and hydrogen ion carrier film were placed on the BPG substrate prepared in Example 1. The Nernst response change of the electrode coated with No. 6 was measured using the circuit shown in FIG. The measurement results are shown in Table 1.

Table 1 Comparative electrode: Saturated sodium chloride calomel electrode (SSCE
) Measurement temperature = 37°C <Example 2> Dioctyl sebacate (DO3) was used instead of DOP as a plasticizer for creating the hydrogen ion carrier film 6 of Example 1.
A coated electrode was prepared in the same manner as in Example 1 except that .

Experimental Example 2> The results of experiments on pH characteristics using the coated electrode of Example 2 are shown in Table 1, and it takes about 7 days for the standard potential (Eo) to become stable.

<Examples 3 to 5> Coated electrodes were prepared in the same manner as in Example 1, except that the types of embedding agents/solvents used were changed from those in Example 1 and shown in Table 2 below.

Table 2 <Experimental Examples 3 to 5> Table 3 shows the test results of testing the durability of sensor characteristics (Nernst equation Eo, slope) using the coated electrodes of Examples 3 to 5.

The same results as in Example 3 were also obtained with the carboxylic acid ester plasticizer (benzophenonetetofoundenylcarboxylic acid ester: BTCU).

Table 3 As a result, the combination of IIOM-THF has good stability in both the Eo and the slope of the Nernst equation.

The combination of DOA-THF has a large fluctuation in Eo, and 0OS
- In the case of cyclohexanone, it became clear that both Eo and the slope of the Nernst equation had large fluctuations.

These results are summarized in Figure 3(a).

Shown in (b).

<Example 6> A conductive carbon film 15 is formed on the surface of the gate insulating layer 14 of the MOSFET, and a redox functional layer 16 and a hydrogen ion carrier film 17 are formed on the padding in the same manner as in Examples 1 and 7. did. This is shown in FIGS. 4 and 5. Incidentally, the formation of the conductive carbon film 15 is as follows.

(1) MOSFET MOSFET is an FE that has a structure in which a p-type 5L-5102 gate insulating film is layered on a p-type silicon wafer.
T (so-called insulated FET) was used. This one is p
It is fabricated using general planar technology using photolithography on a molded silicon wafer, and is further coated with an insulating film 14 made of silicon nitride using a sputtering method. Note that 11 is a drain, 12 is a source, 13 is an oxide film, and 18 is a silicon substrate.

(2) Conductive carbon film A conductive carbon film (thickness: 2000 layers) was formed as a conductive layer 15 on the surface of the gate insulating film 14 of the MOSFET thus produced using ion beam sputtering.

Experimental Example 6 Using the electrode of Example 6, conductivity characteristics (Eo, Nernst equation slope) and durability tests were examined in the same manner as in Experimental Example 1. First, the same results as in Example 1 were obtained. was obtained, and it became clear that the durability of the electrode was improved by using DOP in the hydrogen ion carrier film.

<Example 7> The preparation of the carbon electrode and the coating of the redox functional layer 3 by the electrolytic polymerization method were the same as in Example 1.

The method for producing the hydrogen ion carrier film 4 was the same as in Example 1, but the composition was changed to that shown in Table 4.

Table 4 (Hydrogen ion carrier composition) As a plasticizer, adipine polyester: PN-250 (manufactured by Adeka Argus Co., Ltd. (HachiDEKA ARGtlS)) was used instead of dioctyl sebacate.

Experimental Example 7> Using the pH sensor produced according to Example 7 as a working electrode,
When the electromotive force for the reference electrode (SSCE) was measured in a phosphate buffer solution and the electromotive force was plotted against pH,
The slope and standard electrode potential (Eo) were measured over time. For comparison, the electrode prepared in Example 2 was also measured.

The results are shown in Table 5 and FIGS. 6(a) and (b).

As can be seen from this result, for all electrodes until 30 days after fabrication, the slope was 61.8 ± 0.5 mV/pH (37 °C), which was the theoretical value (61.5 mV/pH (37 °C)). It approximates well and is stable. The reference electrode potential is also stable up to 30 days.

Experimental Example 8> A severe test (accelerated test) was conducted using the pH sensor manufactured according to Example 7, in which the same measurement as in Experimental Example 7 was performed, but the electrode was stored in a 60° C. oven. Table 6
The results are shown below.

Table 6 Experimental Example 9> The influence of oxygen gas was observed using the pH sensor manufactured according to Example 7.

Bubble a certain concentration of oxygen and nitrogen mixed gas into the phosphate buffer solution of pH sensor 7.4, and the oxygen gas partial pressure in the solution will be 20 mmHg, 150 mmHg, and 400 mmHg.
When the potential of the pH sensor was measured at each partial pressure, it was found that the change in potential was within 2 mV at all electrodes, and was not affected by oxygen gas.

In this embodiment, a hydrogen ion carrier film is used as a representative ion carrier film, but other ion carrier films can have similar effects. In addition, a conductive substrate,
The conductive layer is not limited to carbon, but may also be made of gold, platinum, N, or the like. Furthermore, the structure of the film electrode and the FET sensor is not limited to this example.

[Effects of the Invention] According to the present invention, by using a plasticizer that is difficult to dissolve in a solution and has ion mobility in the ion carrier membrane, mutual stability between the plasticizer and the electropolymerized membrane is increased. An ion carrier membrane and an ion sensor equipped with the same can be provided.

As a result, it was found that: 1. By using DOP as a plasticizer in the PVC ion carrier film in a membrane-coated electrode, it was found that an excellent ion sensor with stable sensor characteristics for more than one month could be produced.

2. It was found that a large amount of plasticizer dissolved in PVC affected the durability of electrodes (coated wire type electrodes, 15FET electrodes).

[Brief explanation of drawings]

Figure 1 is a structural diagram of the coated electrode prepared in Examples 1 to 5, Figure 2 is a measurement diagram of the coated electrode in Figure 1, and Figures 3 (a) and (b) are the coated electrodes of Examples 1 to 5. Figures 4 and 5 are diagrams showing the characteristics of the electrode. Figures 4 and 5 are structural diagrams of the ion sensor created in Example 6. Figures 6 (a) and (b) are diagrams showing the characteristics of the coated electrode in Example 7. be. In the figure, 1... BPG, 2... Conductive adhesive, 3...
・Heat shrink tube, 4... Urethane adhesive, 5...
Redox functional layer, 6... Hydrogen ion carrier film, 7.
... Lead wire, 11 ... Drain, 12 ... Source, 13 ... Oxide film, 14 ... Insulating film, 15 ...
Conductive layer, 16... Redox functional layer, 17... Hydrogen ion carrier film, 18... Silicon substrate. Figure 1 Figure 2 Figure 3 (0) Figure 3 (b) Figure 4 Figure 6 (0)

Claims (21)

[Claims] (1) An ion carrier film made of polyvinyl chloride plasticized with a plasticizer and sensitive to predetermined ions, wherein the plasticizer is a phthalate ester plasticizer, a maleate ester plasticizer, or an adipic ester plasticizer. An ion carrier membrane characterized by being selected from at least one of a plasticizer and a carboxylic acid ester plasticizer. (2) As a phthalate ester plasticizer, the number of carbon atoms is 4.
14. The ion carrier membrane according to claim 1, wherein the ion carrier membrane is one of 14 to 14. (3) The ion carrier membrane according to claim 1 or 2, wherein di-2-ethylhexyl phthalate (DOP) is used as the phthalate plasticizer. (4) The ion carrier membrane according to claim 1, wherein dioctyl maleate (DOM) is used as the maleate ester plasticizer. (5) The ion carrier membrane according to claim 1, wherein dioctyl adipate (DOA) is used as the adipic acid ester plasticizer. (6) The ion carrier membrane according to claim 1, wherein an adipic acid polyester is used as the adipic acid ester plasticizer. (7) The ion carrier membrane according to claim 1, wherein benzophenonetetraundecylcarboxylic acid ester (BTCU) is used as the carboxylic acid ester plasticizer. (8) An electrically conductive substrate, a redox functional layer covering the electrically conductive substrate and exhibiting a redox function, and an ion carrier film covering the redox functional layer, the ion carrier film containing a plasticizer. An ion carrier membrane sensitive to predetermined ions, which is made of polyvinyl chloride plasticized with An ion sensor characterized by being selected from at least one ester plasticizer. (9) The ion sensor according to claim 8, wherein the phthalate ester plasticizer has 4 to 14 carbon atoms. (10) The ion sensor according to claim 8 or 9, wherein di-2-ethylhexyl phthalate (DOP) is used as the phthalate plasticizer. (11) The ion sensor according to claim 8, wherein dioctyl maleate (DOM) is used as the maleate ester plasticizer. (12) The ion sensor according to claim 8, wherein dioctyl adipate (DOA) is used as the adipate plasticizer. (13) The ion sensor according to claim 8, wherein an adipic acid polyester is used as the adipic acid ester plasticizer. (14) Benzophenonetetraundecyl carboxylic acid ester (BTCU) as a carboxylic acid ester plasticizer
9. The ion sensor according to claim 8, wherein the ion sensor is used. (15) A gate insulating layer of an FET, a conductive layer covering the gate insulating layer, a redox functional layer that exhibits a redox function covering the conductive layer, and an ion carrier film covering the redox functional layer. The ion carrier film comprises:
An ion carrier film sensitive to predetermined ions, made of polyvinyl chloride plasticized with a plasticizer, the plasticizer being a phthalate ester plasticizer, a maleate ester plasticizer, an adipic ester plasticizer, An ion sensor characterized by being selected from at least one carboxylic acid ester plasticizer. (16) As a phthalate ester plasticizer, the number of carbon atoms is 4.
15. The ion sensor according to claim 15, wherein the ion sensor is an ion sensor according to claim 15. (17) Claim 15 or 1, characterized in that di-2-ethylhexyl phthalate (DOP) is used as the phthalate plasticizer.
The ion sensor according to item 6. (18) The ion sensor according to claim 15, wherein dioctyl maleate (DOM) is used as the maleate ester plasticizer. (19) The ion sensor according to claim 15, wherein dioctyl adipate (DOA) is used as the adipate plasticizer. (20) The ion sensor according to claim 15, wherein an adipic acid polyester is used as the adipic acid ester plasticizer. (21) Benzophenonetetraundecyl carboxylic acid ester (BTCU) as a carboxylic acid ester plasticizer
16. The ion sensor according to claim 15, wherein the ion sensor is used.