JPH0634682Y2 - Electrode mounting structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an electrode mounting structure, and more specifically, a state in which an opening is formed at a predetermined position to maintain an accurate positional relationship with a casing. The present invention relates to an electrode mounting structure for mounting electrodes.

<Prior Art and Problems to be Solved by the Invention> Conventionally, as in a glucose sensor, a substance to be measured is measured based on an electric signal corresponding to the amount of the substance generated or lost as a result of an electrochemical reaction. There is provided a measuring device for measuring the presence or absence or the concentration.

Many of such measuring devices have a relatively large structure and require considerable skill in handling, and therefore have not been widely used.

Focusing on such a point, the inventors of the present invention are conducting research on a glucose sensor that is small and easy to handle, but in order to miniaturize it, it is necessary to miniaturize the electrode itself. In addition, in order to simplify the handling, it is necessary to improve the workability of exchanging consumable parts and the liquid tightness in the vicinity of the electrodes.

Therefore, it is necessary to fix the miniaturized electrode in a relatively small space of the casing with high-precision positioning, and it is very troublesome to fix the electrode, and the fixing position accuracy is not sufficient. There is a problem that it cannot be increased.

More specifically, if the workability of attaching the electrode to the casing is important, the electrode attachment space formed in the casing should be made larger and the electrode should be fixed by screwing, etc. Due to the large space, it is not possible to improve the positioning accuracy with respect to the space, and due to the large surplus space, the seal member for ensuring liquid tightness becomes large, which inevitably results in error size. Therefore, it becomes difficult to secure uniform liquid tightness over the entire circumference of the electrode.

On the other hand, when the electrode mounting accuracy with respect to the electrode mounting space is emphasized, the extra space formed in the vicinity of the electrode becomes small and it becomes very difficult to perform screwing or the like. It will be impossible. Therefore, it is conceivable to form an engaging portion that is accurately positioned in advance in the electrode mounting space and engage the engaging portion formed on the electrode base portion. Since the dimensional accuracy and the positional accuracy of the joint cannot be improved so much, the electrode mounting accuracy cannot be improved so much, and the manufacturing cost as a whole increases. In particular, when the casing is divided into an upper member and a lower member, the electrode is fixed to the lower member, and then the upper member is attached to the lower member, the accuracy of attaching the electrode to the lower member is improved. However, there is no guarantee that the accuracy of attaching the electrode to the upper member can be kept sufficiently high in the end, and as a result, the relative positional relationship between the opening formed in the upper member and the electrode varies considerably. There is a problem.

In addition, the above-mentioned problem appears not only in the electrode of the glucose sensor but also in the attachment structure of the electrode such as the urea sensor and the cholesterol sensor.

<Purpose of Invention> This invention was made in view of the above problems,
An object of the present invention is to provide an electrode mounting structure capable of improving the electrode mounting accuracy in the electrode mounting space without complicating the structure.

<Means for Solving the Problems> In order to achieve the above-mentioned object, the electrode mounting structure of the present invention has a base for mounting an electrode composed of an upper member and a lower member, and inserts the electrode at a predetermined position of the upper member. A common opening is formed, an engaging portion is provided at a predetermined position of the lower member, and an electrode is provided on the engaging portion of the lower member and an electrode base portion having a diameter larger than that of the electrode body. It is supported in a loosely engaged state with the mating part, and a cylindrical body with an outer diameter larger than the inner diameter of the opening is screwed into the protruding part of the electrode body that projects above the opening. Of the upper member with the tubular body and the electrode base,
A predetermined position close to the opening is sandwiched.

However, it is preferable that the engaging portion provided on the lower member of the base on which the electrode is mounted is a boss and the engaging portion provided on the electrode base is a hole. In this case, it is preferable that the electrode has a large-diameter flange at the base and a hole that engages with the boss at a predetermined position of the flange.

Further, it is preferable that the electrode has an annular packing near the base.

<Operation> With the above electrode mounting structure, when the electrode is mounted with the upper part of the electrode protruding to the outside of the casing through the opening formed at the predetermined position of the upper member of the base on which the electrode is mounted, The engaging portion provided on the lower member of the base to be mounted and the engaging portion provided on the electrode base portion are loosely engaged with each other, and in this state, a cylindrical body having an outer diameter larger than the inner diameter of the opening is formed. The electrode can be fixed to the casing by being screwed into the protruding portion of the electrode. Then, in this case, the relative positional relationship between the opening and the outer periphery of the electrode can be accurately determined by moving the electrode within the movement range allowed by both engaging parts before completely screwing the cylindrical body. Can be set, and then the cylindrical body can be completely screwed in, so that electrode mounting can be achieved in a state where highly accurate positioning is performed. Further, if the opening is formed so as to match the outer diameter of the electrode, it is possible to perform highly accurate positioning by simply screwing the tubular body without moving the electrode. Electrode attachment can be achieved.

When the engaging portion provided on the lower member of the base to which the electrode is attached is a boss and the engaging portion provided on the electrode base is a hole, the boss does not project to the outside. The boss can be reliably prevented from being damaged, and the position of the boss can be easily confirmed to easily and surely achieve the engagement with the hole of the electrode base.

If the electrode has a large-diameter flange at the base and a hole that engages with the boss at a predetermined position of the flange, a lead wire, a signal output terminal, etc. are provided. It is possible to form a hole that engages with the boss without any effect on the electrode body, and press the peripheral portion of the opening between the cylindrical body and the flange to attach the electrode to the base. The electrodes can be fixed.

Furthermore, when the electrode has an annular packing near the base, the tubular packing is screwed into the electrode to compress and deform the annular packing, and the deformed bulge portion of the annular packing causes the electrode to move. Since it is strongly pressed against a predetermined position of the base to be mounted, liquid tightness can be improved and
The electrode can be reliably fixed to the base on which the electrode is mounted in combination with the engagement between the tubular body and the peripheral edge of the opening.

<Examples> Hereinafter, detailed description will be given with reference to the accompanying drawings illustrating examples.

FIG. 4 is a plan view showing a state in which the present invention is applied to a glucose sensor, and FIG. 5 is a vertical sectional view showing a hinge portion (13).
The enzyme electrode (2), the sponge (3), and the preservative storage unit (4) are attached to the casing (1) consisting of a base (11) (12) that is openably and closably connected to each other via There is.

FIG. 1 is an enlarged vertical cross-sectional view showing the structure of an enzyme electrode mounting portion.
FIG. 2 is an exploded perspective view in which the base (11) is composed of an upper member (11u) and a lower member (11d), and the tip end portion of the upper member (11u) is formed by the tubular body (5). ), The enzyme electrode (2) is attached. Then, an electrode insertion opening (14) having an inner diameter equal to the outer diameter of the enzyme electrode (2) is formed at a predetermined position of the upper member (11u), and one at a predetermined position of the lower member (11d).
A pair of temporary fixing bosses (15) are formed.

More specifically, the upper enzyme electrode (2) includes a working electrode (21) made of Pt and a counter electrode (2) made of Ag.
2) with a large diameter flange (2
4) and a hole (25) into which the boss (15) can be loosely inserted is formed at a predetermined position of the flange (24). Then, an immobilized GOD membrane (28) on which glucose oxidase (hereinafter abbreviated as GOD) is immobilized
Are laminated so as to cover both the electrodes (21, 22).

The upper member (11u) has a push-in portion in a predetermined range around the opening (14), and a hanging portion (16) facing the boss (15) is formed at a predetermined position on the lower surface of the push-in portion. In addition, a hanging part (17) is formed at the opening edge. An annular packing accommodating space (18) is formed between the hanging parts (16) (17). Further, a protrusion (19) for attaching the seal packing is formed at a predetermined position on the upper surface of the pressing portion. It should be noted that the engaging portion (81) that engages with one end of the diffusion limiting film holding plate (8) and the diffusion limiting film holding plate (8) are located at predetermined positions that face each other across the push-in portion. An engagement portion (82) that engages with a predetermined position near the other end portion is provided, and the diffusion limiting film holding plate (8) is positioned by the both engagement portions (81) and (82), and diffusion limiting is performed. Solution to be measured drop hole (8) formed on the membrane holding plate (8)
3) is made to face the center of the opening (14). A diffusion limiting film (84) is attached so as to cover the solution to be measured dropping hole (83).

The tubular pair (5) has an outer diameter larger than that of the opening (14), and has an inner surface formed with a female screw (51) that is screwed into a male screw (26) formed on the outer periphery of the electrode body (23). ) Is formed, and moreover, a projection (52) that engages with an attachment / detachment jig (not shown) is formed at a predetermined position on the outer circumference. A cap (27) is attached to a recess formed on the outer periphery of the upper part of the tubular body (5), and an immobilized GOD film (is formed between the upper end surface of the tubular body (5) and the cap (27). The tubular body (5) is screwed into the electrode body (23) by sandwiching the peripheral edge of the electrode (28) to fix the immobilized GOD film (28) to the electrodes (21) (2).
It is made to adhere to the surface of 2).

In addition, the seal packing (6) has a ridge (1
9) has an annular groove (61) to engage with it, and also has an outwardly inclined tongue piece (62) on the upper part, and moreover, it has a tongue in comparison with the elastic strength of the base. The elastic strength of the piece (62) is set small.

The enzyme electrode (2) is added to the casing (1) having the above structure.
The operation when mounting is as follows.

First, attach the flange (2) to the boss (15) of the lower member (11d).
The hole (25) of 4) is engaged, and then the upper member (11u) is fixed to the lower member (11d) so that the electrode body (23) is loosely inserted into the opening (14). In the state where the upper member (11u) is fixed to the lower member (11d), the O-ring (7) as the annular packing is accommodated in the annular packing accommodation space (18), and the O-ring (7) The lower end surface of () is in contact with the flange (24).

In this state, since the tip of the electrode body (23) is projected upward through the opening (14), the tubular body (5) is screwed in from the projecting end side of the electrode body (23). The electrode body (23) can be fixed to the base (11). More specifically, if the tubular body (5) is screwed in, the distance between the lower end face of the tubular body (5) and the flange (24) becomes smaller, and finally the tubular body (5) and the flange ( While pressing the hanging part (17) with 24),
The electrode body (23) can be provided to the upper member (11u) by compressing and deforming the O-ring (7) housed in the annular packing housing space (18). The electrode body (23) fixed in this way
Is accurately positioned with respect to the opening (14), and as a result, is accurately positioned with respect to both the engaging portions (81) and (82).

When the glucose concentration in the solution to be measured is measured using the glucose sensor to which the enzyme electrode (2) is attached as described above, one end of the diffusion limiting membrane holding plate (8) is engaged. The state of being engaged with the part (81) (see FIG. 6A)
Then, by rotating the diffusion limiting film holding plate (8),
When a predetermined position near the other end is engaged with the engaging portion (82), the diffusion limiting film (84) attached to the diffusion limiting film holding plate (8) comes into contact with the surface of the enzyme electrode (2). At the same time, the measurement target solution dropping hole (83) formed in the diffusion limiting film holding plate (8) is in a state of directly facing the center of the enzyme electrode (2) (see FIG. 6B).

Therefore, in this state, the solution to be measured may be dropped on the upper surface of the diffusion limiting film holding plate (8), and the solution to be measured in which glucose diffusion is limited by the diffusion limiting film (84) is immobilized on the GOD film ( 28) Of the working electrode (21) and the counter electrode (22)
And a current signal corresponding to the amount of H ₂ O ₂ produced is produced.

Therefore, the glucose concentration can be detected based on this current signal.

When the measurement of the glucose concentration is completed, the diffusion limiting film holding plate (8) is removed by operating in the reverse order, and then the hinge (13) is centered and the base (11) ( If the sponge (3) is brought into contact with the surface of the enzyme electrode (2) by contacting it with 12), the immobilized GOD membrane (28) is kept in a wet state, so that the activity of the immobilized GOD membrane (28) is suppressed. The enzyme electrode can be stored for a long period of time without lowering. In this state, the enzyme electrode (2)
Since the seal packing (6) is attached to the periphery of the, the leakage of the storage solution in the storage state can be reliably prevented.

The present invention is not limited to the above-described embodiment. For example, as shown in FIG. 3, a boss is provided at a predetermined position of the electrode body (23) and a hole is provided at a predetermined position of the lower member (11d). It is possible to provide the opening (14) and the electrode body (23).
It is possible to fix the electrode body (23) by screwing the tubular body (5) while adjusting the position of the electrode body (23) with a diameter slightly larger than that of the tubular body. As (5), a structure having a main body portion having an outer diameter equal to that of the opening (14) and a flange portion having an outer diameter larger than the opening (14) is adopted, and the electrode body (23) is positioned by the main body portion. The electrode main body (23) can be fixed by pinching the hanging part (17) with this, and it can also be applied when attaching electrodes other than the glucose sensor. It is possible to make various design changes within the range that does not.

<Effect of the Invention> As described above, in the present invention, the electrode body is temporarily fixed,
After that, the electrode body can be attached with high accuracy by simply screwing the tubular body into the electrode, and since the measurement conditions can be made uniform, it is possible to greatly suppress variations in measurement data. It has a practical effect.

[Brief description of drawings]

FIG. 1 is an enlarged vertical cross-sectional view showing the structure of an enzyme electrode mounting portion, FIG. 2 is an exploded perspective view, FIG. 3 is a vertical cross-sectional view of a main portion showing another embodiment, and FIG. 4 is a glucose sensor of the present invention. FIG. 5 is a plan view showing a state in which the present invention is applied to FIG. 5, FIG. 5 is a longitudinal sectional view, and FIG. 6 is a view for explaining an operation for measuring glucose concentration. (1) …… Casing, (2) …… Enzyme electrode, (5) …… Cylinder, (7) …… O ring, (14) …… Opening, (15) …… Boss, (24)… … Flange, (26) …… Male thread, (51) …… Female thread

Claims (4)

[Scope of utility model registration request] 1. A base on which an electrode is mounted comprises an upper member and a lower member, an opening for inserting an electrode is formed at a predetermined position of the upper member, and an engaging portion is provided at a predetermined position of the lower member. The electrode is supported in a state where the engaging portion of the lower member and the engaging portion provided on the electrode base portion having a diameter larger than that of the electrode body are loosely engaged, and the electrode body A tubular body having an outer diameter larger than the inner diameter of the opening is screwed into a projecting portion projecting above the opening, and the tubular body and the electrode base portion clamp a predetermined position of the upper member close to the opening. Electrode mounting structure characterized by being 2. The electrode mounting structure according to claim 1, wherein the engaging portion of the lower member is a boss, and the engaging portion provided on the electrode base is a hole. 3. The utility model registration claim 2 according to claim 2, wherein the electrode has a large-diameter flange at the base and a hole engaging with the boss at a predetermined position of the flange. Electrode mounting structure. 4. The utility model registration claim 2 or 3, wherein the electrode has an annular packing near the base.
The electrode mounting structure according to item.