A microorganism number-measuring apparatus includes a container holder holding container that accommodates a liquid into which microorganisms are released, power supply unit applying a microorganism-collecting voltage and a microorganism number-measuring voltage to measurement electrode that is dipped in container held by the container holder, and reuse prevention unit that makes measurement electrode burn out after a measurement operation thereof. With this configuration, it is possible to prevent improper reuse of the measurement electrode.

THIS APPLICATION IS A U.S. NATIONAL PHASE APPLICATION OF PCT INTERNATIONAL APPLICATION PCT/JP2010/006867.

TECHNICAL FIELD

The present invention relates to a microorganism number-measuring apparatus for measuring, for example, the number of microorganisms (the number of bacteria) present in an oral cavity.

BACKGROUND ART

Measuring cells of conventionally-known microorganism number-measuring apparatuses have a configuration as follows.

The conventional measuring cell includes a container, a measurement space, a liquid containing space, an agitator, and a measurement electrode. A sampling portion disposed at a lower end of a stick-like specimen-sampling carrier is inserted into the container from a top-surface opening of the container The measurement space and the liquid containing space are sequentially disposed upward from the bottom surface of the container. The agitator is disposed on a basal plane of the measurement space. The measurement electrode is disposed above the agitator in the measurement space. The liquid containing space accommodates a liquid (sample liquid).

In addition, a body of the microorganism number-measuring apparatus is disposed outside the measurement space of the container, and includes a driving unit to drive the agitator. The body performs a measurement of the number of microorganisms by using the measuring cell.

When performing the measurement of the number of microorganisms, after the measuring cell is set in the body of the microorganism number-measuring apparatus, the sampling portion of the stick-like specimen-sampling carrier that has collected microorganisms is inserted into the container of the measuring cell from an upper portion thereof. On this occasion, the sampling portion is disposed in the measurement space disposed in a lower portion of the container, together with the liquid accommodated in the liquid containing space of the container. After that, a driving unit disposed below and outside the container drives to rotate the agitator which is disposed on the basal plane of the measurement space. With the rotation of the agitator, the sampling portion is struck to receive impacts, which thereby releases the microorganisms of the sampling portion into the sample liquid.

The released microorganisms are carried to the measurement electrode by an agitated-water flow of the sample liquid agitated by the agitator. Then, the number of the microorganisms is measured at the measurement electrode.

Note that, after finishing the measurement of the number of microorganisms, a user discards the sampling portion and the sample liquid, together with the measuring cell having the measurement electrode (see, for example, Patent Literature 1 listed below).

In this conventional case, the measuring cell having the measurement electrode is discarded after finishing the measurement of the number of microorganisms, and then a fresh measuring cell is used for the next measurement. Accordingly, since a measurement of the number of microorganisms can always be performed by using a fresh measuring cell, the apparatus has been claimed to be a highly reliable and useful device.

On the other hand, however, in the above conventional case, there has been a problem that it is difficult to prevent improper use of measuring cells.

That is, with a measuring cell once used for measuring, the top-surface of the container thereof remains in an open state for easy removal of the used sample liquid from the measuring cell. Hence, there is a possibility for the user to erroneously consider that the measuring cell would be still useable only if the sample liquid is replaced. Based on the consideration, the user would erroneously reuse the used measuring cell, with the sample liquid thereof being replaced.

However, after having been once used for measurement, the measuring cell is in the state where invisibly small microorganisms remain attached to the measurement electrode thereof, even if the sample liquid has been replaced. For this reason, reuse of the measurement electrode once used for measurement will spoil results of the measurement.

CITATION LIST

Patent Literature

SUMMARY OF THE INVENTION

In view of the above mentioned problem, an object of the present invention is to prevent improper use of measurement electrodes.

A microorganism number-measuring apparatus according to the invention includes: a container holder that holds a container accommodating a liquid into which microorganisms are released; a power supply unit that applies a microorganism-collecting voltage and a microorganism number-measuring voltage to a measurement electrode that is dipped into the container held by the container holder; and a reuse prevention unit that makes the measurement electrode burn out after finishing a measuring operation thereof.

Moreover, a microorganism number-measuring apparatus according to the invention includes: a container that accommodates a liquid into which microorganisms are released; a container holder that holds the container; a measurement electrode that is dipped in the container held by the container holder; a power supply unit that applies a microorganism-collecting voltage and a microorganism number-measuring voltage to the measurement electrode; and a reuse prevention unit that makes the measurement electrode burn out after finishing a measuring operation thereof.

That is, in the microorganism number-measuring apparatus according to the invention, the reuse prevention unit is designed to make the used measurement electrode physically burn out after finishing the measuring operation.

Hence, for the next measurement, it is possible to confirm the burnout of the measurement electrode before starting measuring the number of microorganisms, which results in the prevention of reuse of the improper measurement electrode.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1is a perspective view illustrating a configuration of microorganism number-measuring apparatus100according to the first embodiment of the invention.FIG. 2is a perspective view of microorganism number-measuring apparatus100according to the first embodiment of the invention in a state where bacteria-measuring cell1is loaded therein. And,FIG. 3is a cross-sectional view illustrating a configuration of bacteria-measuring cell1in the microorganism number-measuring apparatus according to the first embodiment of the invention.

Microorganism number-measuring apparatus100is a device for measuring the number of microorganisms (the number of bacteria) present in a specimen (saliva, for example) taken from inside an oral cavity. Microorganism number-measuring apparatus100includes loading portion (one example of a container holder)2at a top-surface thereof at which bacteria-measuring cell1is loaded. Moreover, at the inside of microorganism number-measuring apparatus100, measurement unit4(seeFIG. 7) is disposed and coupled with measurement electrode3of bacteria-measuring cell1shown inFIG. 3.

Loading portion2has a cylindrical configuration in which the top-surface thereof is opening5. A lower portion of bacteria-measuring cell1is inserted from opening5as shown inFIG. 2.

A configuration of bacteria-measuring cell1will now be described with reference toFIG. 3.

Bacteria-measuring cell1includes container6, thin film9, thin film10, and measurement electrode3. Container6is composed of polycarbonate and has a blind cylinder shape with an open top-surface. Thin film9partitions the inside of container6into lower measurement space7and upper liquid containing space8. Thin film10covers liquid containing space8of container6. Measurement electrode3is disposed at a central portion of measurement space7in an up-down direction. Moreover, liquid containing space8accommodates pure water11as a liquid for measurement.

That is, as shown inFIG. 3, measurement space7and liquid containing space8are sequentially disposed toward an upward direction from the bottom surface of container6.

Incidentally, thin film9and thin film10are each composed of a metal foil, specifically an aluminum foil. Thin film9is fixed by the outer periphery thereof to stepped portion12disposed at a lower portion of liquid containing space8of container6. And, thin film10is fixed by the outer periphery thereof to flange13disposed at an upper opening of liquid containing space8of container6.

Moreover, measurement electrode3is prepared by depositing silver on a PET, i.e. a substrate, by vapor deposition (or depositing palladium by sputtering), and then trimming it by laser processing.

Next, a configuration of measurement electrode3will now be described.FIGS. 4 and 5are views for illustrating a configuration of measurement electrode3in the microorganism number-measuring apparatus according to the first embodiment of the present invention.

As shown inFIG. 4, measurement electrode3has a configuration in which comb-like electrodes16and17are respectively coupled with terminals14and15, in an area between terminals14and15.FIG. 5shows a configuration of comb-like electrodes16and17.

Comb-like electrodes16and17are disposed in an opposed state in which both are very close to one another entirely along a long path thereof, thereby generating electrostatic capacity therebetween.

When the number of microorganisms (the number of bacteria) to be detected is large, the electrostatic capacity between comb-like electrodes16and17becomes large. Therefore, use of the variation in the electrostatic capacity allows the measurement of the number of microorganisms.

FIG. 6is a perspective view of microorganism number-measuring apparatus100according to the first embodiment of the invention in a state where cap18, for example, is placed to cover bacteria-measuring cell1as a container cover thereof, after bacteria-measuring cell1is loaded to the apparatus. As shown inFIG. 6, at a substantially central portion of cap18, through-hole18A is disposed, through which stick20configuring stick-like specimen-sampling carrier19(a cotton swab, for example) penetrates.

Here, a detailed description of the configuration and operation of microorganism number-measuring apparatus100will be given.FIG. 7is a view illustrating the detailed configuration of microorganism number-measuring apparatus100according to the first embodiment of the invention.

Specimen-sampling carrier19is provided with sampling portion21to which cotton is balled up, at a lower end of the carrier as shown inFIG. 7.

Here, how to use microorganism number-measuring apparatus100will be described. First, in the embodiment, a user takes stick20of specimen-sampling carrier19and rubs an inside of the oral cavity of a patient with sampling portion21. In this way, the user is able to collect microorganisms (bacteria) together with saliva by using sampling portion21.

Next, an upper end (an end at which sampling portion21is not disposed) of specimen-sampling carrier19is placed at a central portion of thin film10of bacteria-measuring cell1shown inFIG. 3, and then pushed straight down. In this way, the upper end of specimen-sampling carrier19pierces a hole in thin film10and a hole in thin film9subsequently.

With this state, the user enlarges the holes pierced in thin film10and thin film9, by rotationally moving stick20of specimen-sampling carrier19in a concentric manner. This causes pure water11held in liquid containing space8to flow into measurement space7, resulting in a submergence of measurement electrode3below the water surface of pure water11.

Next, the user once pulls out specimen-sampling carrier19from bacteria-measuring cell1. Then, the user inserts specimen-sampling carrier19into measurement space7of bacteria-measuring cell1, with sampling portion21being downward, as shown inFIG. 7. And then, the user places cap18to cover container6such that an upper end of stick20of specimen-sampling carrier19penetrates through through-hole18A of cap18, as shown inFIGS. 6 and 7. As a result, sampling portion21is disposed below the water surface of pure water11in measurement space7so as to be in a submerged state.

In this state, at a location over container6of bacteria-measuring cell1, through-hole18A of cap18serves as a supporting portion to movably support an upper portion of stick20of specimen-sampling carrier19. Sampling portion21and a portion of stick20located below the supporting portion are able to rotate in a horizontal direction, with the supporting portion being used as a loose rotational axis.

FIG. 7shows an electrical block diagram as well, of microorganism number-measuring apparatus100. Rotor22is disposed beneath the bottom of container6. Magnets23and24are disposed at rotor22.

Consequently, when motor25, i.e., a driving unit, rotates rotor22with magnets23and24, the rotating magnets entail a rotation of stick-like agitator26that is movably disposed at the inside bottom of container6. By rotating, agitator26strikes sampling portion21of specimen-sampling carrier19.

As a result, sampling portion21is subjected to impacts in a flapping manner, which allows the oral-cavity microorganisms collected in sampling portion21to be effectively released into pure water11.

Moreover, stick20moves in a conical manner such that through-hole18A supporting stick20is used as a tip of the cone. Therefore, in measurement space7, not only the rotational force of sampling portion21but also the rotational force of stick20adjacent to sampling portion21works as a force to agitate pure water11. As a result, pure water11in measurement space7is subjected to the agitating action large enough to effectively reach comb-like electrodes16and17located above.

Then, after finishing the release operation described above, a detection of the microorganisms by using comb-like electrodes16and17is started.

Regarding the measurement of microorganisms, a further description will be given with reference toFIG. 7. In order to collect microorganisms released into pure water11, alternating-current power supply unit27A of power supply unit27applies an alternating voltage (a microorganism-collecting voltage) for collecting bacteria to terminals14and15(seeFIG. 4) of measurement electrode3. Thereby, the microorganisms in pure water11are polarized to positive and negative states by a dielectrophoretic force caused by the applied voltage. As a result, the microorganisms are attracted to a portion of comb-like electrodes16and17shown inFIG. 5. In this process, the electrostatic capacity becomes large with increasing number of the microorganisms (bacteria) collected between comb-like electrodes16and17.

Measurement unit4measures a magnitude of the electrostatic capacity in accordance with an instruction from control unit28, and sends the result thereof to computing unit29. Computing unit29determines a rate of change in the electrostatic capacity based on the measurement result of measurement unit4, converts the rate into the number of the microorganisms (bacteria) by the same procedure as conventional one, and then displays the result thereof on display unit30via control unit28.

Incidentally, operation unit31shown inFIG. 7is one for the user to input instructions for a sequence of operations described above.

In microorganism number-measuring apparatus100according to the embodiment, disconnection unit32is disposed inside the control unit28as a reuse prevention unit for bacteria-measuring cell1which has been used for a measurement, as shown inFIG. 7. Disconnection unit32makes measurement electrode3physically burn out after finishing measuring microorganisms. Therefore, for the next measurement, it is possible that disconnection detecting unit33disposed inside measurement unit4confirms the burnout of measurement electrode3before starting measuring the bacteria.

Hence, in case a user tries to reuse bacteria-measuring cell1(reuse of measurement electrode3), it is possible to prompt the user to use another fresh bacteria-measuring cell1(use of fresh measurement electrode3).

As a result, by using microorganism number-measuring apparatus100according to the embodiment, it is possible to prevent improper reuse of bacteria-measuring cell1(improper reuse of measurement electrode3).

Hereinafter, a detailed description will be given regarding the prevention of improper reuse of bacteria-measuring cell1.

In bacteria-measuring cell1which has been used for measuring bacteria, the top surface of container6thereof is in the open state for easy removal of used pure water11from bacteria-measuring cell1. Hence, there is a possibility for a user to erroneously consider that bacteria-measuring cell1would be still useable only if the sample liquid is replaced. Based on the erroneous consideration, the user would replace pure water11in bacteria-measuring cell1and use the cell again.

However, after having been once used for a measurement, used bacteria-measuring cell1is in the state where some of invisibly small microorganisms present during the measurement still remain inside container6and on measurement electrode3, even if pure water11thereof is replaced. For this reason, reuse of bacteria-measuring cell1once used for a measurement makes it impossible to perform a proper measurement.

Moreover, comb-like electrodes16and17of bacteria-measuring cell1are made of silver. Therefore, after used pure water11is removed from bacteria-measuring cell1, microscopic organic materials in the air will adhere to comb-like electrodes16and17, which makes it impossible to perform a proper measurement. For this reason as well, reuse of bacteria-measuring cell1(measurement electrode3) once used for a measurement spoils proper results from the measurement.

In contrast, in microorganism number-measuring apparatus100according to the embodiment, disconnection unit32, i.e., the reuse prevention unit, is disposed so as to treat used bacteria-measuring cell1such that measurement electrode3thereof is made to physically burns out after finishing measurement operation. Therefore, improper reuse of bacteria-measuring cell1can be prevented.

Next, an operation of microorganism number-measuring apparatus100according to the first embodiment of the present invention will be described with reference to a flowchart.

FIG. 8is the flowchart illustrating the operation of microorganism number-measuring apparatus100according to the first embodiment of the invention.

Then, the user operates operation unit31shown inFIG. 2to start a preparation for measurement (Step S3). After starting the preparation for measurement, control unit28confirms coupling of bacteria-measuring cell1, and disconnection detecting unit33confirms a state of comb-like electrodes16and17of measurement electrode3(Step S4). Specifically, control unit28starts by causing motor25(one example of a driving unit to rotate pure water11) to rotate at a speed of 1200 rpm.

Thereby, stick-like agitator26disposed at the inside bottom of cylindrical container6is rotated to agitate pure water11. Pure water11is rotated around a center axis in an up-down direction, which generates an agitated-water stream in a spiral state (a water stream rotating inside container6). In addition, agitator26strikes sampling portion21of specimen-sampling carrier19, thereby causing microorganisms of sampling portion21to be released into pure water11. After that, the microorganisms are carried to comb-like electrodes16and17by the agitated-water stream of pure water11.

In this process, in accordance with an instruction from disconnection detection unit33disposed in measurement unit4, alternating-current power supply unit27A applies an alternating-current voltage of 800 kHz and 1V to comb-like electrodes16and17. If comb-like electrodes16and17are in a proper state, electric current flows between comb-like electrodes16and17, with the microorganisms being used as a medium which have been carried to comb-like electrodes16and17.

On the other hand, if comb-like electrodes16and17have burned out by means of disconnection unit32, no electric current flows between comb-like electrodes16and17. Therefore, by detecting the state of the electric current, disconnection detecting unit33is able to detect whether or not comb-like electrodes16and17have burned out.

When fresh bacteria-measuring cell1is used, disconnection detecting unit33judges that comb-like electrodes16and17are in a proper state without burnout, thus the confirmation of coupling of the cell is completed.

In the case where bacteria-measuring cell1is judged to be in a proper state, automatic suspending process is started (Step S5). Specifically, control unit28causes motor25to rotate at a speed of 3000 rpm, which thereby releases remaining microorganisms from sampling portion21into pure water11. Note that the automatic suspending process is carried out for, for example, one minute.

Next, a measurement of the number of microorganisms (the number of bacteria) is performed (Step S6). Specifically, control unit28changes the speed of rotation of motor25from 3000 rpm to 1200 rpm that is suitable for collecting bacteria. In the embodiment, during the measurement of the number of microorganisms, the speed of rotation of rotor22is reduced so that the microorganisms collected to comb-like electrodes16and17will not be detached from comb-like electrodes16and17due to the agitated-water stream.

Then, control unit28instructs alternating-current power supply unit27A of power supply unit27to apply both a bacteria-collecting voltage (microorganism-collecting voltage) of 3 MHz, 10 V and a measuring voltage (microorganism number-measuring voltage) of 800 kHz, 1V to comb-like electrodes16and17, simultaneously for 20 seconds. And then, measurement unit4measures the magnitude of the electrostatic capacity, and sends the result thereof to computing unit29. Computing unit29determines a rate of change in the electrostatic capacity, converts the rate into the number of microorganisms (the number of bacteria) by the same procedure as conventional one, and then displays the result thereof on display unit30via control unit28. Thus, the measurement is completed.

Next, in order to prevent improper use of used bacteria-measuring cell1, comb-like electrodes16and17of measurement electrode3are made to burn out (Step S7). Specifically, for comb-like electrodes16and17, disconnection unit32switches over the connection from alternating-current power supply unit27A to direct-current power supply unit27B. Then, direct-current power supply unit27B applies a direct current voltage of 5V for 10 seconds, as a disconnection voltage.

In this way, comb-like electrodes16and17burn out, and after that it is impossible for bacteria-measuring cell1to be reused. Regarding the burnout treatment, a more detailed description will be given later.

In the case where the user tries to reuse bacteria-measuring cell1whose comb-like electrodes16and17have burned out, the operation proceeds again in sequence of steps S1, S2, and S3shown inFIG. 8. However, in step S4, because of comb-like electrodes16and17having burned out, no electric current flows between comb-like electrodes16and17. Then, disconnection detecting unit33of measurement unit4detects the state of electric current, and measurement unit4thereby judges that comb-like electrodes16and17are not in a proper state. Then, control unit28displays on display unit30a notice of caution for use of fresh bacteria-measuring cell1, reading “Use Fresh Bacteria-Measuring Cell1,” for example. After that, the successive treatments are halted (Step S8).

As a result, it is possible to prevent reuse of bacteria-measuring cell1(measurement electrode3) which has been once used, and therefore prevent improper use of bacteria-measuring cell1(measurement electrode3).

Here, the burnout treatment of comb-like electrodes16and17will be described in detail with reference to the drawings.FIGS. 9A,9B, and10are views for illustrating the burnout treatment of comb-like electrodes16and17in the microorganism number-measuring apparatus according to the first embodiment of the invention. Note thatFIGS. 9A and 9Bare simplified views, for explanation, of measurement electrode3shown inFIG. 5.FIG. 10is a magnified view of portion A1ofFIG. 9.

Measurement electrode3shown inFIG. 9Ais prepared by depositing silver on PET, i.e., a substrate, by vapor deposition, and then trimming it to form comb-like electrodes16and17with a laser having a spot diameter of 25 μm. Therefore, in comb-like electrodes16and17, as shown inFIG. 10, interelectrode groove34between the electrodes is configured such that circles are sequentially connected one another with a partial overlap to form a continuous shape. Hence, comb-like electrodes16and17have undulating sides which are disposed opposite to one another and symmetric with respect to center line35that connects centers of the consecutive circles.

Incidentally, in the embodiment, since the spot diameter of the laser is set to 25 μm, then gap width36between comb-like electrodes16and17is 25 μm. And, in the example ofFIG. 10, pitch37between comb-like electrodes16and17is set to 50 μm.

Starting with the normal state shown inFIG. 9A, when comb-like electrodes16and17are made to burn out, disconnection unit32switches over the power supply unit from alternating-current power supply unit27A to direct-current power supply unit27B, and couples the power supply unit with terminals14and15of measurement electrode3. Thereby, a direct-current voltage of 5 V is applied to comb-like electrodes16and17coupled with terminals14and15, with comb-like electrode16being positive and comb-like electrode17being negative.

This leads to a concentrated electric current flow across portion38at which comb-like electrodes16and17are located closest one another as shown inFIG. 10. For this reason, heat is generated at negative-side comb-like electrode17to which the electric current concentrates, thereby causing the silver of comb-like electrode17to peel off from the PET.

Incidentally, the peel-off starts from an edge portion of negative-side comb-like electrode17. First, once edge portion T1is lifted from the PET due to the heat, the agitated-water stream (the water stream rotating inside container6) of pure water11peels and tears off edge portion T1. Next, when edge portion T2is lifted from the PET, the water stream peels and tears off edge portion T2. In this manner, such peeling gradually proceeds to edge portions T3, T4, and so on. Finally, negative-side comb-like electrode17becomes in a state of a complete burnout (burned down) as shown inFIG. 9B. As a result, it is possible to make measurement electrode3burn out.

Note that the time period for applying the direct-current voltage by direct-current power supply unit27B is set to one during which negative-side comb-like electrode17burns out completely. The time period varies depending on solution electric conductivity of pure water11. The solution electric conductivity varies depending on the quality and quantity of saliva of the patient, which is collected together with the microorganisms when rubbing the inside of the oral cavity of the patient with sampling portion21for collecting the microorganisms. Also, the solution electric conductivity varies depending on the quality and quantity of adhesive which bonds sampling portion21to stick20of specimen-sampling carrier19. That is, these adhesive and saliva of the patient are eluted into pure water11together with the microorganisms from sampling portion21, which causes variations in the solution electric conductivity of pure water11.

Regarding conditions for a complete burnout of negative-side comb-like electrode17, when the solution electric conductivity is high, the direct-current voltage becomes low and the time period thereof becomes short because of ease of electric current flow. In contrast, when the solution electric conductivity is low, the direct-current voltage becomes high and the time period thereof becomes long. In the embodiment, in order to make measurement electrode3burn out completely even if the solution electric conductivity is low, the applied voltage is set to 5V and the time period thereof is set to 10 seconds.

Note that, during burning out of measurement electrode3, the agitated-water stream plays a role in aiding comb-like electrode17in peeling off, as described above. Moreover, after peeling-off of comb-like electrode17, the agitated-water stream rapidly quenches heat of comb-like electrode17, which allows the burnout of measurement electrode3with an appropriate environment for burnout being kept.

As a result, it is possible to prevent reuse of bacteria-measuring cell1(measurement electrode3) which has been once used, and therefore prevent improper use of bacteria-measuring cell1(measurement electrode3).

Furthermore, during burning out of measurement electrode3, negative-side comb-like electrode17is in a state of a complete burnout as shown inFIG. 9B, which allows visual confirmation of bacteria-measuring cell1(measurement electrode3) having burned out. Hence, the user is able to recognize such as “this is a used measurement electrode”. From this viewpoint, it is possible to prevent improper use of bacteria-measuring cell1(measurement electrode3).

As described above, in the first embodiment, for preventing reuse of measurement electrode3, microorganism number-measuring apparatus100performs the following operations after finishing measuring the number of microorganisms. That is, disconnection unit32switches over the power supply unit from alternating-current power supply unit27A to direct-current power supply unit27B, and couples the power supply unit with terminals14and15of measurement electrode3. Thereby, a direct-current voltage of 5 V is applied such that comb-like electrode16is positive and comb-like electrode17is negative.

In contrast, in the second embodiment, for preventing reuse of measurement electrode3, an alternating-current voltage is applied to comb-like electrodes16and17as a burnout voltage from alternating-current power supply unit27A without using direct-current power supply unit27B, in accordance with an instruction from disconnection unit32.

That is, in the embodiment, a reuse prevention unit causes alternating-current power supply unit27A of power supply unit27to apply the alternating-current voltage, as a burnout alternating-current voltage, between comb-like electrodes16and17of measurement electrode3. The applied alternating-current voltage has a frequency lower than those of a microorganism-collecting voltage (3 MHz, 10 V) and a microorganism number-measuring voltage (800 kHz, 1 V).

FIGS. 11A and 11Bare views illustrating burnout treatment of comb-like electrodes16and17in a microorganism number-measuring apparatus according to the second embodiment of the invention.FIG. 11Ashows a state before the burnout alternating-current voltage (10 Hz, 10 V) described above is applied for 10 seconds between comb-like electrodes16and17in order to prevent reuse of measurement electrode3.FIG. 11Bshows a state after the burnout alternating-current voltage (10 Hz, 10 V) described above is applied for 10 seconds between comb-like electrodes16and17in order to prevent reuse of measurement electrode3.

In the embodiment, as shown inFIG. 11B, comb-like electrodes16and17are in a state where both electrodes have largely burned out to blisteringly segmented. That is, in this embodiment both comb-like electrodes16and17burn largely out, while in the first embodiment negative-side comb-like electrode17burns out by applying direct-current voltage.

In accordance with the embodiment, in the configuration of microorganism number-measuring apparatus100shown inFIG. 7, it is possible to simplify the configuration of power supply unit27by eliminating the need for direct-current power supply unit27B through means that alternating-current power supply unit27A applies the burnout alternating-current voltage (10 Hz, 10 V) for 10 seconds.

Note that, in the embodiment, regarding the burnout alternating-current voltage (one example, 10 Hz, 10 V) applied between comb-like electrodes16and17from alternating-current power supply unit27A, it is intended to use an alternating-current voltage with a frequency lower than commercial frequencies (50 Hz or 60 Hz, in most countries in the world including Japan).

Moreover, in the embodiment as well, it is after finishing measuring the number of microorganisms (the number of bacteria) that comb-like electrodes16and17are made to burn out by applying the burnout alternating-current voltage (10 Hz, 10 V) between comb-like electrodes16and17from alternating-current power supply unit27A.

Furthermore, in the embodiment as well, before measurement operation of measurement electrode3, the burnout detection of measurement electrode3is performed.

Specifically, in a similar way to the first embodiment, in accordance with an instruction from disconnection detection unit33disposed in measurement unit4, an alternating-current voltage of 800 kHz and 1V (identical to the microorganism number-measuring voltage) is applied to comb-like electrodes16and17from alternating-current power supply unit27A. Then, if comb-like electrodes16and17are in a proper state, electric current flows between comb-like electrodes16and17, with the microorganisms (bacteria) being used as a medium, which have been carried to comb-like electrodes16and17.

On the other hand, if comb-like electrodes16and17have burned out in accordance with an instruction from disconnection unit32, no electric current flows between comb-like electrodes16and17. Therefore, by detecting the state of the electric current, disconnection detecting unit33is able to detect whether or not comb-like electrodes16and17have burned out.

Note that, in the embodiment, the alternating-current voltage applied to measurement electrode3for performing burnout detection is one that has a frequency higher than that of the burnout alternating-current voltage (10 Hz, 10 V). Specifically, the burnout detection is configured so as to be performed by applying the microorganism number-measuring voltage (800 kHz, 1 V) to measurement electrode3.

As described in the embodiment, during burning out of measurement electrode3, comb-like electrodes16and17become in a state where both have largely burned out as shown inFIG. 11B. Therefore, the user is able to visually confirm that bacteria-measuring cell1(measurement electrode3) has burned out. Hence, the user is able to recognize that this is a used measurement electrode. From this viewpoint, it is possible to prevent improper use of bacteria-measuring cell1(measurement electrode3).

INDUSTRIAL APPLICABILITY

As described above, the present invention is useful for, for example, microorganism number-measuring apparatuses for measuring the number of microorganisms (the number of bacteria) present in an oral cavity, because the invention provides them with the capability of preventing improper use of measurement electrodes thereof.

REFERENCE MARKS IN THE DRAWINGS

8liquid containing space

27power supply unit

27A alternating-current power supply unit

27B direct-current power supply unit

33disconnection detection unit

38portion at which electrodes are located closest one another