JPS58167951A - Chlorine ion sensor - Google Patents

Abstract

PURPOSE:To prevent a chlorine ion sensor from being influenced by disturbing ingredients in blood and urine by using such a substance obtained by fixing covalently bonded 4th class ammonium chloride and dodecyl benzene sulfonic acid as an ion sensitive membrane. CONSTITUTION:A field-effect type transistor chlorine ion sensor is composed of a substrate semiconductor made of P type Si on which an n type source 2 and a drain 3 are installed, and further between those two electrodes, an insulation gate composed of silicon dioxide 7, silicon nitride 8 and a chlorine sensitive membrane 9 is provided. The chlorine sensitive membrane 9 is formed by such a method that at first, a thin film 9 of 5mum is formed by coating chloromethyl polystyrene, and on this film 9, 4th class ammonium chloride is fixed, and further sulfonic groups are fixed by dodecyl benzene sulfonic acid solution. The chlorine ion sensor composed like this is not influenced by disturbing organic ingredients in blood and urine and capable of making stable measurements.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chlorine ion sensor for measuring chlorine 111 in a sample solution, and particularly to a chlorine ion sensor for measuring chlorine 111 in blood and urine.
The present invention relates to a chloride ion sensor suitable for I-degree measurement.

Conventional chloride ion sensors have widely used solid chloride ion sensitive membranes in which AgCt and *g*8 imitation powders are mixed and heated and pressurized to form a disk shape. When this chloride ion-sensitive membrane comes into contact with body fluids such as blood and urine, unnecessary interfacial reactions such as adsorption of proteins, lipids, etc. to the sensitive membrane surface occur.
There was a drawback that the concentration measurement error became large. Conventionally, a thin film such as a dialysis membrane was closely coated on the surface of the sensitive membrane, but the problem was that the reproducibility of the close coat was poor and production could not be carried out at a high yield. Furthermore, in terms of performance, there were drawbacks such as a decrease in response speed and an increase in the time required for analysis.

In addition, a MOSFET type (insulated gate field effect transistor) chloride ion sensor has recently been developed (Patent No. 54).
66091), hgctemg as a chloride ion sensitive membrane
Because it uses an organic material in which ts is dispersed, AgC6
, there is a drawback that unnecessary interfacial reactions between Agm8 and components present in body fluids cannot be essentially controlled. Also F
The ion-sensitive film is formed on the ET gate by dispersing silver particles and coating them with scanning equipment, which has the drawback that coating on the extremely small gate surface cannot be performed with high precision, making it difficult to miniaturize the sensor. there were.

An object of the present invention is to provide a highly accurate minute chlorine ion sensor that is not affected by interfering components in blood or urine.

A feature of the present invention is that a negative micro-electron beam resist based on either chloromethylated polystyrene or chlorinated polystyrene is coated on the insulated gate portion of a field effect transistor made of a semiconductor, silicon dioxide, or silicon nitride, and quaternary ammonium The objective is to form a chloride ion sensitive membrane in which chloride and dodecylbenzenesulfonic acid are covalently immobilized.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view showing the structure of an example of the field effect microtransistor chloride ion sensor of the present invention. In this case, PM11111 silicon with a specific resistance of 10 Ω is used as the substrate semiconductor l. By photo-etching and enlarging, the na11 north 2 and n#1 drain 3 are formed, and furthermore, the Kn4'' region inside the north 2 and drain 3 is formed for the purpose of making good contact with the aluminum interconnection mill.Next, the substrate semiconductor 1
The surface is treated by thermal oxidation and CVD to form electrical insulating layers 6.7.8 of silicon dioxide and silicon nitride. Further, an external electrode lead-out band 11 is formed by aluminum vapor deposition. Next, the surface portion excluding the channel region sandwiched between the source 2 and drain 3 is covered with a silicon nitride electrical insulating film 10 to ensure water resistance of the sensor. The chlorine ion sensitive film 9 is formed on the insulating film 8 as follows. First, a negative electron beam resist mainly composed of chloromethylated polystyrene is applied to the insulating layers 8 and 10.
Spread evenly over the entire surface using a spinner. The film thickness is determined by the spinner rotation speed and the viscosity of the resist used. The thickness of the sensitive film is preferably in the range of 0.5 μm to 10 μm.

If it is too small, pinholes will occur and the sensor operation will become unstable.

Using the above resist with a viscosity of 30 cp, the rotation speed was 200 O.
A thin film of 5 μm was formed at rpm. Next, a region other than the top of the insulating layer 8 was exposed to light using an electron beam irradiation device with an electron density of 0.8×10 −IC/cd and an acceleration voltage of 2017. After blanching, the resist surface marked Ila on the semiconductor surface was treated with triethylamine to immobilize quaternary ammonium chloride on the film 9. Furthermore, sulfonic acid groups were immobilized on the thin film 9 using 3Qwt - dodecylbenzenesulfone ## solution. This treatment must be carried out under mild conditions that do not cause decomposition of the quaternary ammonium chloride previously immobilized on the membrane 9. Finally, the surface area of the conductor in iron is treated with a mixed solution of oxygen plasma, sulfuric acid, and hydrogen peroxide (2:1) to remove unnecessary polymer films other than the upper surface of the insulating film 8. The chloride ion sensor manufactured through the above steps is thoroughly washed with deionized water and then stored in a 100mM potassium chloride aqueous solution. FIG. 2 shows an example of the use of the chloride ion sensor manufactured using the above-mentioned punching machine. A chloride ion sensor 12 and a reference electrode 13 having a liquid junction structure are immersed in a test liquid 14.

The external FET 15 and operational amplifier 16 keep the drain current of the chlorine sensor 12 constant, and the chlorine ion sensor 12
The circuit configuration allows direct reading of the gate voltage. The sensor output voltage is recorded by the recording needle 17. The characteristics of the chlorine sensor 12 are ascertained by the test liquid 14 having a high chlorine ion intensity, and the results are stored and held in the arithmetic storage unit 18.

A test liquid 14 whose chloride ion concentration is unknown is cauterized, its output voltage is calculated by an arithmetic and storage unit, and the chloride ion concentration is printed out by a printer 19.

Next, we investigated the interference of organic components in serum with this chloride ion senna. An interference solution with a known intensity was used as a test solution, and the concentration measurement device shown in FIG. 2 was used for investigation. Table 1 summarizes the concentration of each interfering component in normal serum and the concentration of the above-mentioned test solution. In all cases, there was no interference above smM chloride ion equivalent concentration, confirming that this sensor is suitable for determining serum chloride ion concentrations.

According to the present invention, a highly stable chlorine ion sensor that is not affected by organic interfering components in blood, urine, etc. can be manufactured at a high yield and at low cost. Furthermore, since the ion-sensitive film is formed using an electron beam resist, a sensitive film of any shape can be easily manufactured with good reproducibility, and chlorine senna can be miniaturized.

Table 1

[Brief explanation of drawings]

FIG. 1 shows a sectional view showing the configuration of one row of a field effect transistor chloride ion sensor according to the present invention, and FIG. 2 shows an explanatory diagram of a chloride ion concentration measuring device. 1...p-type silicon, 2.3...n-type silicon, 4.5...
・n0 type silicon, 6.8.10... silicon nitride, 7...
Silicon dioxide, 9... Sensitive polymer film, 11... Aluminum vapor deposited wire, 12... Chlorine ion sensor, 13...
Reference electrode, 14... Test liquid, 1s... FET, 16
...Operation amplifier, 17... Kishu needle, 18... Memory calculator, 19... Printer. (Leap J

Claims (1)

[Claims] 1. An ion-sensitive field effect transistor consisting of a three-layer structure of a semiconductor, an electrically insulating material, and an ion-sensitive film, in which quaternary ammonium quaride and dodecylbenzenesulfonic acid are used as the ion-sensitive film. A chloride ion senna characterized by having a covalently fixed polymer film. 2. 2 of silicon dioxide and valued silicon as the electrical insulating material.
A chloride ion senna according to claim 1, characterized in that a layered structure is used. (F) A chlorine ion sensor according to claim 1, wherein a negative electron beam resist having either chloromethylated polystyrene or chlorinated polystyrene as a base is used as the chlorine ion-sensitive polymer film.