JPS6275342A - Biosensor - Google Patents

Abstract

PURPOSE:To increase measuring accuracy with an electrode reaction, by making a sample blood dripped react with a reaction layer to guide the resulting reaction liquid quickly to a groove at an end face of an electrode section from a liquid retaining layer. CONSTITUTION:A groove 9 is formed at an upper end face of an cylindrical insulating substrate 5 made of a polyvinyl chloride resin or an ABS resin. Platinum is buried so as to be exposed in the groove 9 to form an electrode section which is provided with an electrode system comprising a measuring pole 6, an counter pole 7 and a reference pole 8. A reaction section composed of a triple laminate layer of a reaction layer 1, 1 filtration layer 2 and a liquid retaining layer 3 held with a frame body 4 is provided covering the electrode system. A projection section 13 is so provided on the upper side of a base body 5 that a clearance part 10 surrounded by the frame body 5, the base body 5 and the liquid retaining layer 3 is formed at the position where the projection 13 is set. This aligns the electrode section and the frame body 4 at the centers. Thus, the clearance section 10 between the frame body 4 and the electrode section is made so uniform in the perimeter thereof to transfer a reaction liquid evenly throughout the liquid retaining layer 3 without retention of air in the liquid retaining layer 3 thereby increasing the measuring accuracy with a quick guide of the reaction liquid to the groove 9.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a biosensor that detects a specific component in a biological sample, and particularly relates to an improvement in the structure of an electrode part, and can be widely applied to the medical field, food engineering, etc. It is something.

2. Description of the Related Art Conventionally, a glucose sensor known as this type of sensor had a configuration as shown in FIG. In FIG. 5, 1 is a reaction layer, 2 is a filter, 3 is a liquid retaining layer, and 4 is a frame that holds the periphery of the three layers consisting of 1, 2, and 3.

Further, reference numeral 5 denotes a cylindrical electrode portion having an outer diameter smaller than the inner diameter of the frame, and a measuring electrode 6. Counterpoint 7. Reference electrode 8 is electrode 5
It is exposed on the upper surface 6-1. A groove 9 is provided on the upper surface 5-1 of the electrode portion 5. This state is shown in FIG. 6 as a perspective view of the electrode section.

When a blood sample is dropped from the top, the reaction first proceeds in the reaction layer 1, and the reaction liquid is filtered and removed to remove solid components such as red blood cells and platelets that interfere with the reaction of the measurement electrode. do. Further, the reaction liquid is absorbed into the liquid retaining layer 3.

This liquid retaining layer 3 allows filtration to be carried out quickly. The reaction liquid transferred to the liquid retaining layer 3 fills the exposed grooves 9 of the three electrodes of the cylindrical electrode section. This reaction solution was detected by electrode reaction.

Problems to be Solved by the Invention However, with this conventional structure, there was a problem in 1 that the reaction liquid could not be guided quickly into the groove on the upper surface of the electrode part, resulting in variations in the amount of reaction measured by the electrode reaction. .

The reason for this is that the outer diameter of the cylindrical electrode part 5 is set slightly smaller than the inner diameter of the frame 4. This is because when the blood sample is dropped from the top and penetrated downward, the frame This means is necessary for escaping the air present in the reaction layer from the cavity 10 of the columnar electrode part 5. However, the existence of this void 10 makes it easy for the frame 4 and the electrode section 5 to become misaligned. FIG. 7 is a sectional view showing a defective configuration state. When the inner surface of the frame 4 and the electrode section 5 come into close contact, air that has no place to escape accumulates in the liquid retaining layer 12 near the closely contacted part 11 in FIG. 7, and the air migrates to the liquid retaining layer of the reaction liquid. This caused a problem in that the reaction solution could not be guided quickly into the groove 9 on the upper surface of the electrode part, and the accuracy of the measured reaction amount due to the electrode reaction was lowered.

The present invention solves these problems by making it possible for the dropped blood sample to react in the reaction layer, and for the reaction liquid to be quickly guided to the grooves of the electrode section, thereby improving the measurement accuracy due to the electrode reaction. This is the purpose.

Means for Solving the Problems In order to solve this problem, the present invention provides a protrusion on at least a part of the side surface of the electrode part, and this protrusion partially contacts the inner surface of the frame, so that the frame A uniform gap is provided between the inside of the body and the electrode part to prevent center deviation between the frame body and the electrode part.

Function: With this configuration, no center deviation occurs between the frame and the electrode part, so the gap between the frame and the electrode part is uniformly provided around the circumference, and air is prevented from entering the liquid retaining layer. The reaction liquid is uniformly transferred to the entire liquid retaining layer without accumulation, and the reaction liquid is quickly guided to the groove on the upper surface of the electrode portion, thereby improving measurement accuracy by electrode reaction.

EXAMPLES The present invention will be described below using a glucose sensor as an example of a biosensor.

FIG. 1 is a sectional view of a sensor according to an embodiment of the present invention, and FIG. 2 is a perspective view of an electrode section. A groove 9 with a depth of 0.1 ffil is formed on the upper end surface of a cylindrical insulating substrate 5 made of polyvinyl chloride resin or ABS resin, and platinum is embedded in the groove so as to be exposed, thereby forming a measuring electrode 6 and a counter electrode 7. and a reference electrode 8 constitute an electrode system. The diameter of platinum is about 1 mm, and the cylindrical insulating substrate 5 has a diameter of about 5 to 611 m.

A protrusion 13 was provided on the upper side surface of the insulating base. The protrusion 13 is installed at a position such that a gap 10 surrounded by the frame 4 and the liquid retaining layer 3 at 5 degrees of the base body is formed. As a result, the centers of the electrode portion and the frame coincide. The shape of this protrusion 13 may be semicircular or square, and its protrusion height is approximately 0.6 from the relationship with the frame inner diameter.
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A reaction layer 1 held by a frame 4 so as to cover the electrode system.
Filtration vortex layer 2. A reaction section with a three-layer stack of liquid retaining layers 3 is installed.

The glucose sensor of this example used glucose oxidase as an oxidoreductase and potassium ferricyanide as an oxidized dye conjugated with the oxidoreductase. The reaction layer 1 is made of a nonwoven pulp fabric, and supports the above-mentioned glucose oxidase and potassium ferricyanide fine crystals at a high density. The filter 2 is a porous polycarbonate membrane with a pore diameter of 1 μm, and is used to remove solid components such as red blood cells from the blood. Hydrophilic rayon paper was used for the liquid retaining layer 3.

Other examples of protrusions on the side surfaces of the electrode portions for centering are shown in perspective views in FIGS. 3 and 4.

A notch step 14 is provided on the circumferential surface near the upper end of the rib 13 and the base 5 along the length of the electrode part, and the tip is used as the electrode part, and the outer diameter of the base is slightly smaller than the inner diameter of the frame. This part is used as a protrusion for positioning.

The operating method of this glucose sensor will be explained with reference to FIG. 1. 3Qμ4 drops of blood are added to the reaction layer 1 as a sample liquid. When the dripped glucose in the blood is oxidized by the glucose oxidase supported on the reaction layer 1, potassium ferricyanide is reduced by an enzyme-dye coupling reaction to produce potassium ferrocyanide. The reaction solution thus produced passes through a porous polycarbonate membrane, which is the filtration chamber 2. As it passes through, large solid components such as red blood cells are filtered out. After filtration, the reaction solution is retained in the liquid retaining layer 3 of hydrophilic rayon paper. Since the blood (reaction liquid) after reaction filtration is still highly viscous, it may be difficult for the air in the liquid retention layer to escape.If there is no gap between the inner surface of the frame and the electrode part, the reaction liquid will not flow into the liquid retention layer. Insufficient penetration and retention.

In the present invention, the protrusions 13 and 14 on the side surfaces of the electrode part function as positioning, so that the center of the electrode part does not shift within the frame, and the void part 10 can be formed evenly around the electrode part, and the void part 10 can retain liquid. As air escapes from the layer, the reaction solution uniformly permeates into the liquid retaining layer.

In the case of the configuration shown in FIG. 4, air can escape to the outside through a small gap between the cutout step 14 and the inner surface of the frame 4. Further, the reaction liquid moves from the liquid retaining layer to the groove 9 where the three electrodes on the upper surface of the electrode section are exposed. Here, the voltage of the measurement electrode 6 is adjusted from 0 to +0.0 with reference to the reference electrode 8. The voltage was varied in a sawtooth manner at 0.1 v/sec between IV. Potassium ferrocyanide in the reaction solution is oxidized by sweeping the voltage of the measurement electrode, and an oxidation current flows at this time. This oxidation current is proportional to the amount of change in the dye, and the glucose concentration can be detected.

With the conventional electrode without a protruding part described above, there are cases where sufficient reaction liquid does not flow into the groove on the top surface of the electrode part, and the measurement accuracy is ±2Q%, but with the present invention, the reaction liquid does not flow into the groove. Because it was done quickly, the measurement accuracy improved to ±10%.

Effects of the Invention As described above, according to the present invention, the dropped blood sample reacts in the reaction layer, and the reaction liquid is quickly guided from the liquid retaining layer to the groove on the end face of the electrode part, so that measurement by electrode reaction is possible. 0 which can improve accuracy

[Brief explanation of drawings]

FIG. 1 is a sectional view of a glucose sensor according to an embodiment of the present invention, FIG. 2 is a perspective view showing the electrode part of the sensor, and FIG.
4 is a perspective view showing another example of the electrode section, FIG. 6 is a sectional view showing a conventional glucose sensor, FIG. 6 is a perspective view of the same electrode section, and FIG. 7 is a defective configuration of the sensor. FIG. 1... Reaction layer, 2... Retirement, 3...
...Liquid retaining layer, 4...Frame body, 5...Base body,
6...Measurement electrode, 7...Counter electrode, 8...
...Reference pole, 9...Groove, 1o...Gap, 13.14...Protrusion. Name of agent: Patent attorney Toshio Nakao and one other person II
Figure/-Ansho・1 Figure 2 Figure 3

Claims (1)

[Claims] An electrode part having an electrode system consisting of a measurement electrode, a counter electrode, and a reference electrode on an insulating base; a reaction layer containing an oxidoreductase and an oxidized dye conjugated with the enzyme on the electrode part; and a liquid retaining layer. A biosensor in which a protruding part is provided on at least a part of the side surface of the electrode part, and the protruding part is configured to be in contact with the inner surface of the frame. .