JPS6213003Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a composite sensor consisting of an ion sensor consisting of a gate-insulated field effect transistor having a sensor gate and a liquid junction type comparison electrode.

Conventionally, as this type of ion sensor, one having a structure shown in FIG. 1, for example, is known. In the figure, 1 is a P-type silicon substrate, and an N-type drain 2 and a sensor source 3 are formed on this substrate 1.
is formed. 4, 5, and 6 are the common drain layer 2, the sensor source 3, and each electrode portion of the silicon substrate 1, and 7 is the sensor gate portion, the cross section of which is shown in FIG.

As is clear from FIG. 2, the gate section 7 has a two-layer structure consisting of a silicon oxide layer 8 and a silicon oxide layer 9 formed on the silicon substrate 1, and the sensor gate section 7 has, for example, an ion ion layer. A sensitive layer 10 is coated.

The ion sensor having the above configuration is immersed in the test liquid 12 in the container 11 together with the comparison electrode 13, as shown in the circuit of FIG. A positive potential of a voltage source Vd is connected to the drain 2 of the ion sensor, and a constant current circuit 14 is connected to the source 3 to operate as a source follower circuit. Then, the change in conductivity at the semiconductor surface under the gate insulating film due to the interfacial potential between the gate insulating film of the ion sensor and the test liquid and the change in the interfacial potential at this time are extracted as the source potential Vs. Since this source potential Vs has a linear relationship with the logarithm of the ion concentration, the ion concentration of the test liquid can be measured by measuring this Vs.

The present invention provides a compact and easy-to-manufacture composite sensor that integrates the above-mentioned ion sensor and reference electrode.

An embodiment of the composite sensor of the present invention will be described below with reference to the drawings. FIG. 4 is an explanatory diagram of the composite sensor. After inserting the lead wires 15 connected to the electrode parts 4, 5, and 6 of the ion sensor into the thin tube 16, the sensor is attached to the side wall of the thick tube 17. The sensor is inserted liquid-tight into the tube through the opening 18, and the gate portion 7 of the sensor is located at the tip of the tube. The tip of the tube 17 is sealed by sealing a resin 19 in the gap between the inner wall of the thick tube tip, a part of the tip of the thin tube into which the lead wire is inserted, and at least a portion of the ion sensor excluding the gate. .

On the other hand, the other end of the tube 17 is closed with a rubber stopper 20, and an electrolyte chamber 21 for sealing an electrolyte is formed inside the tube. In addition, the electrolyte chamber 21
A liquid junction portion 25 is provided in the resin 19 to communicate the liquid to be tested. A silver-silver chloride wire 22 is liquid-tightly inserted into the electrolyte chamber through an opening provided in the side wall of the tube. The silver-silver chloride wire and lead wire are connected to a connector 23. 24 is a resin that seals the gap between the opening provided in the side wall of the tube and the lead wire and silver-silver chloride wire.

The material for the thin tube 16 into which the lead wire is inserted must be water resistant, and polyamides such as nylon 6, nylon 11, and nylon 12, polyester, polyethylene, polypropylene, polyvinyl chloride resin, etc., or rubber resins may be used. I can do it. In particular, rubber-like resin is preferred because it can be swollen with a good solvent to make it thicker, pass a lead wire through it, and then be made thinner by evaporating the solvent, so that a thin tube can be kept to a minimum thickness. Examples of this rubbery resin include silicone rubber, urethane rubber, polyisoprene rubber, etc. Silicone rubber is preferable, and in this case, the swelling solvent may be trichlene, hexane, chloroform, etc. I can do it. By this method, the outer diameter of silicone resin with an outer diameter of 300μ and an inner diameter of 100μ is
It is extremely easy to insert three 50μ lead wires. Furthermore, when passing the sensor lead wire through the tube, it is also possible to pass the guard electrode lead wire through the tube at the same time to create a composite sensor with a guard electrode.

The liquid junction 25 that communicates the electrolyte chamber 21 with the outside can be formed by disposing cotton thread, hollow fibers made of a hydrophilic polymer material, or porous ceramics in a resin. Hollow fibers are particularly desirable in terms of reducing the shape of the liquid junction and improving reproducibility, and among them, those made of cellulose, cellulose acetate, ethylene vinyl alcohol copolymer, or polyvinyl alcohol are preferred. Further, pores may be formed in the side wall of the thick tube 17 to serve as a liquid junction.

As the resin for sealing the tip of the thick tube 17, it is preferable to use epoxy resin, silicone resin, or a combination of both.

As the electrolyte, saturated KCl or physiological saline can be used. When used by inserting it into a living body, it is desirable for safety to use physiological saline. Thin tube 1 is the material for thick tube 17.
Although it is the same as in case 6, by using rubber-like resin such as silicone rubber in both cases, it is possible to provide a flexible composite sensor that is extremely excellent for biological measurement.

The silver-silver chloride wire inserted into the electrolyte chamber may be of any flexible type and may have any cross-sectional shape.

FIG. 5 shows another example in which a connector is used as a seal plug in the opening at the other end of the thick tube 17 to close the opening. The electrolyte sealed in the electrolyte chamber in the tube can be injected into the tube before closing the opening at the end of the tube with a connector, or after the opening at the end of the tube has been closed with a connector in advance.
It may also be injected into the tube with a syringe. In this case, the hole made with the injection needle in the side wall of the tube 17 can be sealed with tape or the like.

Figure 6 shows yet another example, with a thin tube 1.
6 and at least the electrode part of the sensor are liquid-tightly fixed with a short tube 26, and then the sensor is inserted into the thick tube 17, and the gap between the thick tube 17 and the short tube 26 is liquid-tightly sealed. This is a still image. In this case, when inserting the sensor into a thick tube, a liquid junction can be easily formed by arranging a hollow fiber outside the short tube.

<Example> A silicone rubber tube with an inner diameter of 0.3 mm and an outer diameter of 0.5 mm for the thin tube 16, and a silicone rubber tube with an inner diameter of 0.5 mm for the thick tube 17.
1.0mm, outer diameter 2.0mm silicone rubber tube, used as an ion sensor, length 6mm, width 0.55mm, thickness 150μ
Using a PH sensor of We fabricated flexible composite PH sensors with lengths of 5 cm, 10 cm, and 15 cm from the side wall of the thick tube to the opening where the sensor and thin tube exit to the outside. A composite sensor with excellent stability and durability was obtained by filling physiological saline as an internal liquid through the opening at the other end of the thick tube. The composite PH sensor fabricated in this way could be stored for a long period of time in a saline-filled pod.

As described above, in the composite sensor of the present invention, the reference electrode and ion sensor are located very close to each other, so that close electrical contact between the two is maintained, providing a sensor free from measurement errors such as AC interference and noise. It became possible.

[Brief explanation of drawings]

Fig. 1 is a plan view showing the structure of the ion sensor, Fig. 2 is a cross-sectional view of the gate part of the ion sensor, Fig. 3 is an electric circuit diagram using the ion sensor, and Figs. is a sectional view of the composite sensor of the present invention. 7...Sensor gate, 15...Lead wire, 17
...Tube, 21...Electrolyte chamber, 22...Silver-
Silver chloride wire, 25...liquid junction means.

Claims (1)

[Scope of utility model registration request] Each electrode 4 of an ion sensor consisting of a gate insulated field effect transistor having a sensor gate 7,
A lead wire 15 coated with resin is connected to 5 and 6, and the lead wire is inserted into a water-resistant thin tube 16 whose one end is connected to the connector 23. Insert the thin tube into the thick tube 17, position the sensor gate at the tip of the thick tube, fill the gap formed between the inner wall of the thick tube and the electrode part of the ion sensor with resin, and close the opening at the tip of the thick tube. The tip of a thin tube with a lead wire inserted through it is embedded and fixed in the resin to form an electrolyte chamber 21 inside the thick tube, and a silver-silver chloride wire 2 is inserted into the electrolyte chamber. A composite sensor characterized in that a liquid junction means 25 is provided in a resin that is tightly inserted and closes the opening at the tip of a thick tube.