JP3267016B2 - Portable measuring instrument - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a portable biochemical measuring instrument using an immobilized enzyme sensor.

[0002]

2. Description of the Related Art Enzymes can be repeatedly and stably used due to their excellent substrate specificity and immobilization technology, and their practical use has been promoted. In recent years, enzymes have been widely used in the fields of food industry and clinical testing. I have. In the inspection field, it is used for detection and quantification of a specific substance in a composite sample using an enzyme, and the following two types of methods have been put to practical use. Part 1
One method is to convert an enzyme reaction amount into a color change by mixing an enzyme and a color-forming reagent, and to optically detect the color change to measure a specific substance (substrate). In this method, a substance that increases or decreases with the enzymatic reaction is electrochemically detected by combining an electrode and an electrode, and a specific substance (substrate) is measured from a change in the amount of electricity.

In the latter method, the enzyme may be mixed with the sample solution and used, but the equipment becomes large-scale.
For general use, immobilization of enzymes that can reduce the size of the device
A combination of thinning and electrodes is used. In this case, it is necessary to keep both the contact between the immobilized enzyme membrane and the electrode and the wet state of the sensor section constant. This is to stabilize the measurement results by keeping the diffusion amount of the target substance (substrate) in the liquid sample to the immobilized enzyme layer and the diffusion amount to the electrode surface of the substance that increases or decreases with the enzymatic reaction constant. is there. Conversely, when the adhesion between the enzyme film and the electrode or the wet state between the enzyme film and the electrode changes, the measurement result changes as a result.

In order to maintain constant adhesion between the electrode and the enzyme film when the enzyme film is mounted, attempts have been made to improve the operability by providing an enzyme film mounting jig, for example. Instability due to failure is inevitable. Further, in order to keep the immobilized enzyme sensor unit in a constant wet state, a method has been used in which the sensor unit is provided in a flow cell and a sample / preservation solution is supplied. However, a pump is required in addition to the flow cell.

[0005] In any case, the size of the apparatus for waterproofing and maintenance of the preservation solution has been increased, and the apparatus has been expensive. Also, it is necessary to dispense a fixed amount of sample and supply it to the sensor, or to collect the sample in a container and immerse the sensor,
Pretreatment of the sample was required. In contrast, in recent years,
It has been proposed that a sponge-like porous material absorb a preservative solution and the porous material is brought into contact with a sensitive surface of an immobilized enzyme sensor to keep the enzyme sensor wet (for example, Japanese Patent Application Laid-Open No. 4-43947). Bulletin, Shokai 64-5
No. 0).

[0006] In this case, the portability is improved due to the miniaturization, but the diffusion limiting film is separated, and it is necessary to attach the diffusion limiting film for each measurement, and the operability and stability cannot be said to be sufficient. Furthermore, the pressure contact state between the electrode and the water absorbing body is apt to change due to the elastic change of the soft water absorbing body, and the circulation of the preservative is also difficult to be performed,
The amount of stored liquid is also reduced. Further, during storage, the container is in a sealed state, and a pressure change due to a temperature change or the like occurs.

[0007]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned conventional problems, and is mainly concerned with miniaturization, improvement of operability, improvement of output stability, and waterproofness. It is an object of the present invention to provide a portable measuring instrument realizing the improvement of the measurement.

[0008]

According to a first aspect of the present invention, there is provided a portable measuring instrument comprising a sensor holder having a built-in enzyme sensor, a measuring circuit, and a power supply section. And a cover which is detachably attached to the measuring instrument main body so as to cover the enzyme sensor protruding from the measuring instrument main body, and has a storage liquid storage section for storing a storage liquid for the enzyme sensor. .

[0009]

In the measuring instrument according to the first aspect, if the cover is removed from the measuring instrument main body at the time of measurement, the sensor holder (that is, the enzyme sensor) appears to be in a measurable state. Conversely, the cover is attached to the measuring instrument main body. If this is the case, the enzyme sensor can be immersed in the storage solution in the cover, so that the enzyme sensor can be maintained in a constant wet state and operability is improved.

By making the sensor holder detachable from the measuring instrument body (claim 2), the enzyme sensor can be replaced together with the sensor holder, so that the enzyme sensor can be easily replaced and the enzyme membrane and the electrode can be replaced. Adhesion is also constant. By fixing the sensor holder to the measuring instrument body in a liquid-tight manner with the fixture (claim 3), the sealing performance is improved and the waterproof performance is improved.

[0011] By providing detection means for detecting whether or not the sensor holder and / or the cover are respectively mounted on the measuring instrument main body, the mounted state or non-mounted state of the sensor holder or the cover is measured. It is possible to make the measuring device automatically judge, the operability is further improved, and the measuring device can be turned on / off by attaching / detaching the cover.

The sensor holder has an opening corresponding to the sensitive part of the enzyme sensor inside the sensor holder. The cross-sectional shape of this opening is semicircular. The sample can be supplied from the section to the sensitive section of the enzyme sensor by supplying the sample to the enzyme sensor, and the method of supplying the sample to the enzyme sensor can be broadened and the usability is improved.
The sensor holder has an opening corresponding to the sensitive part of the enzyme sensor inside the sensor holder, and the opening has a mortar shape (claim 6). Air bubbles are less likely to remain in the opening, and the preservation solution reliably enters the enzyme sensor through the opening.

[0013] The cover encloses the preservation liquid in a sealed space formed by a soft thin film bag and an annular packing member provided therein, and the sensor holder is inserted into the cover through the packing member. This allows the enzyme sensor in the sensor holder to come into contact with the preservation solution in the cover (claim 7), so that the inside of the soft thin film bag can be filled with only the preservation solution, as compared with the conventional case using a water absorber. The storage efficiency of the storage solution is improved.

The cover has an annular packing member provided inside the cover, the packing member has a concave portion provided near the center and a slit portion following the concave portion, and the sensor holder is a concave portion of the packing member. By moving into and out of the cover through the slit and the slit portion (claim 8), it is possible not only to prevent foreign matter such as dust from entering the storage solution from the outside, but also to prevent the storage solution from Can also be prevented from leaking. In addition, since the recess functions as a guide when the sensor holder is inserted (that is, when the cover is attached), the sensor holder can be easily inserted.

As described above, a portable measuring instrument which is reduced in size and weight as a whole and has good operability and reliability is provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A portable measuring instrument according to the present invention will be described below based on an embodiment. FIG. 1 shows a top view of the external appearance of the measuring instrument according to the embodiment, and FIG. 2 shows a side view of the external appearance. This measuring instrument 1
A sensor holder having a built-in enzyme sensor, a measuring circuit body 2 provided with a measuring circuit and a power supply section, and a detachably attached to the measuring instrument body 2 so as to cover the sensor holder protruding from the measuring instrument body 2. And a cover 3 provided with a storage solution storage section for storing the storage solution. The measuring instrument body 2
It has a display section 6 and a battery case 7, and an internal measuring circuit is made up of various electronic components such as a calculator and a buzzer.
As shown in FIGS. 3 and 4, if the cover 3 is removed from the measuring device main body 2, the sensor holder 5 containing the enzyme sensor appears from the measuring device main body 2.

The enzyme sensor built in the sensor holder 5 includes:
For example, as shown in FIG. 5, an integrated planar enzyme sensor 18 includes a base electrode 10 attached to the sensor holder 5 and an immobilized enzyme film 13 laminated on the base electrode 10. Examples of the base electrode 10 include the following two examples,
Is mentioned. A field effect transistor is used as a voltage → current conversion element. In this case, an insulated gate portion is provided at the outermost portion, and an immobilized enzyme layer is formed outside the outermost portion, and a pH change accompanying the enzyme reaction is captured as a gate voltage change (simultaneously converted to a drain current change). A planar oxygen electrode / hydrogen peroxide electrode is used as a current-to-voltage conversion element. In this case, an immobilized enzyme layer is formed on the surface of the sensitive portion, and an increase or decrease in oxygen or hydrogen peroxide accompanying the enzyme reaction is captured as a change in the oxidation current of the base electrode. Various metals are used for the electrodes. Platinum (Pt) is mainly used for the working electrode, and gold (Au) is used for the reference electrode and the counter electrode.
Platinum (Pt), silver (Ag), or the like is used.

Examples of the enzymes used in the enzyme sensor 18 are as follows. Glucose + O ₂ → gluconic acid + H ₂ O ₂ Consumption (decrease) of oxygen (O ₂ ) and hydrogen peroxide (H ₂ O ₂ )
(Increase) and gluconic acid (decrease in pH). Lactate oxidase (LOD) L-Lactate + O ₂ → Pyruvate + H ₂ O ₂ Consumption (decrease) of oxygen (O ₂ ) and hydrogen peroxide (H ₂ O ₂ )
(Increase). Urease Urea + H ₂ O → 2NH ₃ + CO ₂ Ammonia (increase in pH due to decrease in hydrogen ion concentration) and increase in CO ₂ gas are involved. Uricase Uric acid + O ₂ + 2 H ₂ O → Allantoin + H ₂ O + CO ₂ Consumption (decrease) of oxygen (O ₂ ) and hydrogen peroxide (H ₂ O ₂ )
(Increase) and an increase in CO ₂ gas.

A typical example of the immobilized enzyme film 13 is a sandwich structure in which the immobilized enzyme layer 15 made of the above-mentioned enzyme is protected by upper and lower layers. Immobilized enzyme layer 15
Are formed by a cross-linking method using a cross-linking material having a functional group, an entrapment method in which the inside of the gel lattice is covered with a polymer, or the like. The lower protective film 14 restricts the permeation of the interfering substance to the electrode surface if necessary.
Adhesiveness and stability with No. 5 are required, and acetylcellulose, an ion-exchange membrane material, or the like is used. Upper protective film 1
Reference numeral 6 is intended to protect the immobilized enzyme layer 15 and to restrict the diffusion of the substrate into the immobilized enzyme layer 15, and the adhesive layer 6 and the immobilized enzyme layer 15 need to have good adhesion and mechanical strength.

A thin and uniform film can be obtained by using a dip coating method or a spin coating method for forming each of these layers. For example, as the lower protective film 14, a 5% acetylcellulose thin film (solvent composition; acetone: cyclohexanone = 3: 1) is dropped on the metal electrode 12, and the lower protective film 14 is 2,000 rpm.
m for 5 seconds. Immobilized enzyme layer 15
Can be formed by spin coating an enzyme solution obtained by mixing a 0.5% glutaraldehyde solution adjusted with a 0.1 M phosphate buffer (pH 7.0) and an enzyme in the same manner as the lower protective film 14. The upper protective film 16 is a 2.5% acetylcellulose thin film (solvent composition; acetone: ethanol = 1: 1).
Can be formed by dip coating at 1 cm / sec.

In this embodiment, a planar type hydrogen peroxide electrode as the base electrode 10 is formed by selectively forming a thin film of, for example, platinum, gold, or silver as the metal electrode 12 on the surface of an insulating film 11 such as a ceramic or resin film. It is formed in. Further, the immobilized enzyme film 13 cross-links and fixes GOD and LOD as the immobilized enzyme layer 15, and further has an upper protective film 16.
In order to enhance the function of the above, a surface protective film 17 made of nylon lattice or polycarbonate is separately provided on the upper protective film 16.
It is adhered on top.

FIGS. 6 (top view), FIG. 7 (side view), FIG. 8 (longitudinal sectional view), and FIG. 9 (line A- in FIG. 8) show a structural example of the sensor holder 5 incorporating such an enzyme sensor 18. A cross section at A). The planar-type enzyme sensor 18 is housed in the sensor holder 5 except for the sensitive part 21 and the connector part 22. By integrally storing the enzyme sensor 18 in the sensor holder 5, it is not necessary to additionally attach a protective film or the like when replacing the enzyme sensor 18 or when starting the measurement. Moreover, since the enzyme sensor 18 can be replaced by replacing the entire sensor holder 5, the adhesion between the electrode surface and the enzyme film in the enzyme sensor 18 becomes constant without being affected by the replacement operation. The connector 22 of the enzyme sensor 18 protrudes from the sensor holder 5, and the sensor holder 5
Is inserted into the measuring instrument main body 2, the connector section 22 is connected to the circuit inside the measuring instrument main body 2, so that it is not necessary to wire using a lead wire or the like, and operability such as replacement work is improved. And connection reliability is increased.

As shown in FIG. 8, the sensor holder 5 has a portion 30 having an opening 30a (see FIG. 6) corresponding to the sensitive portion 21 of the enzyme sensor 18, and is screwed into this portion 30 to measure A part 31 having a mounting part (not shown) for mounting a waterproof O-ring (not shown) to prevent invasion of water, foreign matter, and the like into the vessel main body 2, and a part 31 having a connector part 22 of the enzyme sensor 18. A portion 32 for positioning and fixing together, a portion 33 for positioning the sensitive portion 21 of the enzyme sensor 18 in a convex shape between the portion 30, and a portion 34 for fixing the vicinity of the sensitive portion 21 of the enzyme sensor 18 together with the portion 33. Become. In addition, these sensor holder parts 30-34
For example, by fixing by welding, it is possible to prevent a sample or cleaning water from entering the sensor holder 5.

In FIG. 9, the surface protective film 17 of the enzyme sensor 18 is adhered and fixed to a support member 37. After the surface protective film 17 is mounted in the sensor holder 30, the enzyme sensor 18 and the sensor holder 33 are separated. These are sequentially inserted, and these are fixed by the sensor holder part 34, and the surface protective film 17 is fixedly adhered to the sensitive part 21 of the enzyme sensor 18. Further, an O-ring 38 is provided inside the opening 30a in order to prevent a sample or cleaning water from entering the sensor holder 5 from the opening 30a of the sensor holder portion 30.

The opening 30a of the sensor holder 30 has a mortar shape (see FIG. 9).
“a” has an elliptical shape that is an ellipse in the longitudinal direction of the sensor holder 5 and a short circle in the transverse direction (see FIG. 6). This allows
When the cover 3 is attached to the measuring instrument main body 2, that is, when the enzyme sensor 18 in the sensor holder 5 is immersed in the storage solution in the cover 3, the storage solution easily enters the opening 30 a. Hardly remain in the opening 30a. Since the tip of the sensor holder 5 has a smooth convex shape (curved shape), it can be easily inserted into the cover 3.

As can be seen from FIG. 9, the sensor holder portion 30 has a semicircular cross section in which the opening 30a is convex, and the sensor holder portion 34 is
Has a cross-sectional shape lower than the cross-sectional curvature of. For this reason,
Even when the sample is directly hung on the sensitive part 21 of the enzyme sensor 18, the sample does not scatter around the opening 30a,
The method of supplying the sample to the opening 30a has a wider selection range, and is convenient. Further, as can be seen from FIGS. 7 and 8, the rear portion of the sensor holder 5 (the sensor holder portion 31,
Since the shape of (32) is asymmetric, erroneous insertion of the sensor holder 5 into the measuring instrument main body 2 can be prevented.

FIG. 10 shows an example of the structure of the cover 3 which is detachably attached to the measuring instrument main body 2 and has a storage solution storing section for storing the preserving liquid, and the tip end of the measuring instrument main body 2 (incorporation of the sensor holder 5). ). The preservation solution in the cover 3 includes a preservation solution bag (soft thin film bag) 40 and ring-shaped fixing members 44 and 45.
And is housed in an internal space formed by the packing member 41 fixed at a predetermined position. The storage liquid bag 40
It is sandwiched and fixed between the inner surface of the wall 42 of the cover 3 and the side surface of the packing member 41. Therefore, the storage solution bag 40
Since it comes into contact with the side surface of the packing member 41 and adheres to the inner surface of the meat wall 42 and the side surface of the packing member 41 by the contraction force, the leakage of the preservation liquid is effectively prevented and the waterproofness is improved. Further, since the storage liquid bag 40 and the packing member 41 are housed and fixed in the cover 3 by the fixing members 44 and 45, when the cover 3 is attached to and detached from the measuring instrument main body 2, that is, when the sensor is inserted into the cover 3, When inserting / removing the holder 5,
Its position is kept constant. The material of the storage solution bag 40 is preferably a material having a high water vapor barrier property, such as a silicon film, a polyethylene film, or a latex film.

Further, a through-hole 43 is formed at an appropriate position of the cover 3 for communicating the inside and the outside of the cover 3 so that the storage liquid bag 40 is maintained at atmospheric pressure. Therefore, the preservation liquid bag 40 freely expands and contracts, and the self-expansion force reduces the internal pressure change due to the attachment / detachment of the cover 3 and protects the sensitive portion 21 of the enzyme sensor 18 from a sudden pressure change.

At the center of the packing member 41, a recess having a shape similar to that of the tip of the sensor holder 5 for inserting the sensor holder 5 is formed, and a slit continuous with the recess is formed. The slit part opens and closes depending on the presence or absence of the sensor holder 5. Preferably, if a shrink ring (not shown) is attached to the slit for assisting opening and closing, the sealing performance when the slide is closed is improved. or,
When the sensor holder 5 is inserted (when the cover 3 is attached), an O-ring 46 is provided between the recess entrance and the fixing member 44 in order to prevent the leakage of the storage solution from the recess of the packing member 41. . These configurations not only prevent foreign substances such as dust from entering the storage solution from outside, but also effectively prevent leakage of the storage solution to the outside.

The slit of the packing member 41 may be formed after the packing member 41 is manufactured.
The packing member 41 may be a two-part member, and the two parts may be combined and press-fitted into the cover 3 to make a portion other than the press-fit portion a free portion, and the free portion may be a slit portion. In order to prevent the sensor holder 5 from being easily detached from the measuring instrument main body 2 due to the attachment / detachment of the cover 3 to / from the measuring instrument main body 2, a fixing tool 51 is provided at the distal end side of the measuring instrument main body 2. The enzyme sensor 18 in the sensor holder 5 is stabilized by being always in a measurement state including a non-measurement period.
The sensor holder 5 is securely fixed so that the sensor holder 5 does not come off from the measuring device main body 2 by touching or washing lightly except for operating the sensor holder 5 when the enzyme sensor 18 is replaced.

Next, the sensor holder 5 (that is, the enzyme sensor 1)
FIG. 11 shows an embodiment in which 8) is provided with detecting means for detecting whether or not the cover 3 is mounted on the measuring device main body 2 while detecting whether or not the cover 3 is mounted on the measuring device main body 2. However, since the structure other than the detecting means is the same as that of the embodiment shown in FIG. 10, the same elements are denoted by the same reference numerals and description thereof will be omitted. In this embodiment, the measuring circuit board 60 is extended to the vicinity of the end of the sensor holder 5 inside the measuring instrument main body 2, and a portion of the circuit board 60 corresponding to the engaging portion between the measuring instrument main body 2 and the cover 3. , A reed relay 61 is attached, and a microswitch 62 is attached to a portion corresponding to an end of the sensor holder 5.
A connector 64 that is electrically connected to the enzyme sensor 18 is attached to a portion of the enzyme sensor 18 protruding from the portion facing the connector portion 22. On the other hand, a magnet 63 is embedded in the corresponding portion of the cover 3.

If such a detecting means is provided, when the cover 3 is mounted on the measuring instrument body 2, the reed relay 61 is turned on by the magnetic action of the magnet 63, and the cover 3 is turned on.
Is detected. Using this,
Since the measurement start state can be automatically set by removing the cover 3, it is not necessary to provide a measurement start switch on the measuring device main body 2. When the sensor holder 5 is inserted into the measuring device main body 2, the connector 22 of the enzyme sensor 18 is connected to the connector 64 of the circuit board 60, and the micro switch 62 is turned ON by the sensor holder 5,
It is detected that the sensor holder 5 is mounted. Therefore, when the cover 3 is attached in a state where the sensor holder 5 is not attached to the measuring instrument main body 2, that is, when the enzyme sensor 18 is not immersed in the preservative solution in the cover 3, a caution is required. Can be.

By providing such a detecting means, it is possible to reliably detect whether the cover 3 or the sensor holder 5 is not mounted. In order to notify the presence or absence of the attachment based on the detection signal, for example, the fact may be displayed on the display unit 6 of the measuring device main body 2 or a sound may be generated by a buzzer or the like. Briefly describing the operation of the measuring instrument 1 configured as described above, at the time of measurement, first remove the cover 3 from the measuring instrument main body 2 and confirm a display or a buzzer sound indicating that measurement is possible, and then place the instrument in the container. The opening 30a of the sensor holder 5 is immersed in the placed sample, or the sample is continuously hung on the opening 30a. Then, after confirming the display of the end of the measurement or the buzzer sound, the measurement operation is terminated, and the measurement result is confirmed by the display. After that, the opening 30a of the sensor holder 5, that is, the vicinity of the sensitive portion 21 of the enzyme sensor 18 is washed with water or the like, and then the cover 3 is attached to the measuring device main body 2.

[0034]

The portable measuring device of the present invention has the following effects because it is configured as described above. (1) In the measuring device according to the first aspect, the measuring device main body including the sensor holder, the measuring circuit, and the power supply unit having the built-in enzyme sensor, and the measuring device main body so as to cover the enzyme sensor protruding from the measuring device main body. It consists of a cover that is detachably attached and has a storage solution storage unit that stores the storage solution for the enzyme sensor. If the cover is removed from the measuring instrument body during measurement, a sensor holder (that is, an enzyme sensor) appears, When the cover is attached to the main body of the measuring instrument, the enzyme sensor can be immersed in the storage solution inside the cover, and not only can the enzyme sensor be kept in a constant wet state, but also the operability is improved. improves. (2) By making the sensor holder detachable from the measuring device main body (claim 2), the enzyme sensor can be replaced together with the sensor holder, and the enzyme sensor can be easily replaced. Adhesion is also constant. (3) By fixing the sensor holder to the measuring instrument body in a liquid-tight manner with the fixture (claim 3), the sealing performance is improved and the waterproof performance is improved. (4) By providing detection means for detecting whether or not the sensor holder and / or the cover are respectively mounted on the measuring instrument main body (claim 4), the mounted state or the non-mounted state of the sensor holder or the cover is measured. It is possible to make the measuring device automatically judge, the operability is further improved, and the measuring device can be turned on / off by attaching / detaching the cover. (5) The sensor holder has an opening corresponding to the sensitive part of the enzyme sensor therein, and the opening in the sensor holder has a semicircular cross-sectional shape (claim 5). The sample can be supplied from the section to the sensitive section of the enzyme sensor by supplying the sample to the enzyme sensor, and the method of supplying the sample to the enzyme sensor can be broadened and the usability is improved. (6) The sensor holder has an opening corresponding to the sensitive part of the enzyme sensor inside the sensor holder, and the opening has a mortar shape (claim 6). This makes it difficult for air bubbles to remain in the opening of the sensor holder, and the preservation solution reliably enters the enzyme sensor through the opening. (7) The cover encloses the preservation liquid in the sealed space formed by the soft thin film bag and the annular packing member provided therein, and the sensor holder is inserted into the cover through the packing member. This allows the enzyme sensor in the sensor holder to come into contact with the preservation solution in the cover (claim 7), so that the inside of the soft thin film bag can be filled with only the preservation solution, as compared with the conventional case using a water absorber. The storage efficiency of the storage solution is improved. (8) The cover has an annular packing member provided therein, the packing member has a concave portion provided near the center and a slit portion following the concave portion, and the sensor holder is a concave portion of the packing member. By moving into and out of the cover through the slit and the slit portion (claim 8), it is possible not only to prevent foreign matter such as dust from entering the storage solution from the outside, but also to prevent the storage solution from Can also be prevented from leaking. In addition, since the recess functions as a guide when the sensor holder is inserted (that is, when the cover is attached), the sensor holder can be easily inserted. (9) Due to the above effects, a portable measuring instrument that is small and lightweight as a whole and has good operability and reliability can be provided.

[Brief description of the drawings]

FIG. 1 is an external top view of a measuring instrument according to one embodiment.

FIG. 2 is an external side view of the measuring instrument shown in FIG.

FIG. 3 is a top view of the measuring instrument shown in FIG. 1 with a cover removed.

FIG. 4 is a side view of the measuring device shown in FIG.

FIG. 5 is a cross-sectional view of a main part showing a structural example of an enzyme sensor housed in a sensor holder.

FIG. 6 is a top view showing a structural example of a sensor holder.

FIG. 7 is a side view of the sensor holder shown in FIG.

8 is a vertical sectional view of the sensor holder shown in FIG.

9 is a cross-sectional view of the sensor holder shown in FIG. 8 taken along line AA.

FIG. 10 is a longitudinal sectional view showing a structural example of a distal end portion of a measuring instrument main body and a cover in a state where a sensor holder is mounted.

FIG. 11 is a longitudinal sectional view showing another example of the structure of the distal end portion of the measuring device main body and the cover in a state where the sensor holder is mounted.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Portable measuring device 2 Measuring device main body 3 Cover 5 Sensor holder 18 Enzyme sensor 21 Sensitive part of enzyme sensor 30a Opening of sensor holder 40 Storage liquid bag (soft thin film bag) 41 Packing member

Continuation of the front page (56) References JP-A-3-237349 (JP, A) JP-A-5-72172 (JP, A) JP-A-4-215057 (JP, A) JP-A-4-43947 (JP) JP-A-1-287455 (JP, A) JP-A-5-249068 (JP, A) JP-A-6-229772 (JP, A) JP-A-5-23125 (JP, U) JP-A-5-23125 1-102757 (JP, U) Hira 4-55560 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 27/28 G01N 27/28 331 G01N 27/327

Claims (8)

(57) [Claims] An enzyme sensor which is detachably attached to the measuring device main body so as to cover a sensor holder having a built-in enzyme sensor, a measuring circuit and a power supply, and an enzyme sensor protruding from the measuring device main body; A portable measuring device, comprising: a cover having a storage solution storage section for storing a storage solution for a sensor. 2. The portable measuring instrument according to claim 1, wherein the sensor holder is detachable from the measuring instrument main body. 3. The portable measuring instrument according to claim 2, wherein the sensor holder is fixed to the measuring instrument main body in a liquid-tight manner by a fixing tool. 4. The portable measuring instrument according to claim 2, further comprising a detecting means for detecting whether the sensor holder and / or the cover are respectively mounted on the measuring instrument main body. 5. The sensor holder according to claim 1, wherein the sensor holder has an opening corresponding to a sensitive part of the enzyme sensor therein, and the opening has a semicircular cross section. Portable measuring instrument. 6. The portable measuring instrument according to claim 1, wherein the sensor holder has an opening corresponding to a sensitive part of the enzyme sensor in the sensor holder, and the opening has a mortar shape. 7. The cover encloses a preservation liquid in an enclosed space formed by a soft thin film bag and an annular packing member provided therein, and the sensor holder penetrates the packing member to cover the storage solution. The portable measuring device according to claim 1, wherein the enzyme sensor in the sensor holder is brought into contact with the storage solution in the cover. 8. The cover has an annular packing member provided inside the cover, the packing member has a concave portion provided near the center and a slit portion following the concave portion, and the sensor holder has 2. The portable measuring instrument according to claim 1, wherein the portable measuring instrument moves forward and backward inside the cover through a concave portion and a slit portion of the packing member.