Patent Description:
The present disclosure relates to a measuring device configured to measure a state of a solution.

Techniques for measuring the concentration of any ions such as hydrogen ions contained in a solution are known.

For example, Patent Literature <NUM> (PTL <NUM>) discloses an Ion Sensitive Field Effect Transistor (ISFET) ion sensor that can be miniaturized and solidified with an excellent reproducibility and stability of measurement results due to an excellent stability of a reference part and an excellent chemical and physical durability.

PTL <NUM> discloses a system for obtaining a pH measurement. The system includes a disposable probe and a reader. The disposable probe comprises multiple indicating electrodes and at least one reference electrode. The reader is configured to operably engage with the disposable probe and obtain pH information for a sample.

PTL <NUM> discloses a sensor that includes a film disposed over at least one sensing section for optimizing the functioning and/or results from the sensor. The film includes at least one dissolvable layer.

PTL <NUM> discloses a material detector that includes a plurality of sensor sections and sealing section for blocking each of the plurality of sensor sections from the outside. The material detector can designate a sensor section and remove the sealing section corresponding to the designated sensor section to enable detection of the concentration of a material.

PTL <NUM> discloses an electrochemical sensor that includes a working electrode, a counter electrode and a reference electrode formed on an insulating substrate. An examining electrode is provided to enable examination of the electric potential of the reference electrode and detection of abnormalities.

PTL <NUM> discloses a measurement device for measuring a property of a fluid, in particular a pH-value of said fluid, comprising: a housing comprising a housing section to be immersed into the fluid during measurement operation, and an aperture foreseen in an outside wall of the housing section for exposing a single sensor for measuring the property of the fluid to the fluid, when the housing section is immersed into the fluid. This allows quick and easy replacement of the single sensor and characterizes in that, a number of at least two sensors for measuring the property are foreseen, each of the sensors is mounted in a different outside surface region of a movable mechanical support, and the mechanical support is movably secured inside the housing.

However, a portion of a measuring unit in contact with a solution deteriorates with use due to causes such as adhesion of foreign matter, alteration, scraping, etc., and an accurate measurement signal cannot be output from the measuring unit. In the case of the ion sensor described in PTL <NUM>, for example, an ion sensitive film gradually deteriorates due to contact with a solution. In such a case, the user needs to replace the ion sensor with a new one in a short period of time, which is inconvenient.

It is therefore an object of the present disclosure to provide a measuring device that can measure a state of a solution over a long period of time and improves user convenience.

A measuring device according to some embodiments is a measuring device configured to measure a state of a solution. The measurement device of the present invention is defined in claim <NUM>. The measuring device includes a measuring unit configured to output a measurement signal associated with the state of the solution, a protection unit attached to the measuring unit, and a controller configured to obtain information on the state of the solution on the basis of the measurement signal output from the measuring unit. The measuring unit has a first part in a usable state that contributes to output of the measurement signal by coming into contact with the solution, and a second part that is isolated from the solution by the protection unit and is in a standby state for measurement. The information on the state of the solution includes a pH concentration, the measuring unit may have a glass electrode unit, a first reference electrode unit and a second reference electrode unit used for glass electrode type pH measurement, the first part may have a pair including the glass electrode unit and the first reference electrode unit, and the second part may have the second reference electrode unit. The protection unit has a protection plate that isolates the second part of the measuring unit from the solution, and the protection plate is composed of at least one of biodegradable resin and acid-soluble resin. In this manner, the state of the solution can be measured over a long period of time and the user convenience is improved. More specifically, the measuring unit has the second part in a standby state for measurement, thus the cycle of maintenance work including calibration and refill of an inner solution is extended, which allows for a long-term measurement. For example, with the measuring device, continuous measurement on a year-to-year basis is possible. Moreover, the cycle of maintenance work including calibration and refill of an inner solution is extended even when a conventional glass electrode type pH measuring device is used, thus a long-term measurement is possible.

The second part of the measuring unit is not in contact with the solution, so deterioration of the second part of the measuring unit is suppressed. The second part of the measuring unit can remain unused while the measurement by the first part is continued. Since the protection plate is composed of at least one of biodegradable resin and acid-soluble resin, the protection plate is decomposed or dissolved by the solution even if it is detached from the measuring unit. Therefore, the protection plate can be prevented from remaining as a foreign matter in the solution.

In an embodiment, the protection unit may further include a heater that heats an attaching portion of the protection plate to the measuring unit, which enables control of the state of the attaching portion of the protection plate to the measuring unit by heating by the heater.

In an embodiment, the attaching portion may include a thermally soluble adhesive having a melting point higher than the temperature of the solution and lower than the temperature at which it is heated by the heater, and the protection plate may be attached to the measuring unit by the thermally soluble adhesive. Thus, when the thermally soluble adhesive included in the attaching portion is melted through heating by a heater, the protection plate is detached from the measuring unit. Therefore, control by the heater allows control of the second part of the measuring unit to switch from the standby state for measurement to the usable state, which makes control of switching easy.

In an embodiment, when determining that a measured value of the information on the state of the solution exceeds a predetermined range that can be measured by the first part of the measuring unit, the controller may detach the protection plate from the measuring unit through heating by the heater, and obtain the measurement signal based on the second part. In this manner, even if it is impossible to measure based on the first part of the measuring unit, it is possible to switch to measurement based on the second part of the measuring unit. Therefore, the state of the solution can be measured over a long period of time, and the user convenience is improved.

In an embodiment, an inner solution or gel with known properties may be filled between the protection plate and the second part of the measuring unit. This allows for calibration of the measuring device using the second part of the measuring unit until immediately before the controller detaches the protection plate.

In an embodiment, the distance between the internal electrode contained in the glass electrode unit and the internal electrode contained in the first reference electrode unit may be the same as that between the internal electrode contained in the glass electrode unit and the internal electrode contained in the second reference electrode unit. Therefore, the distance between the internal electrode of the glass electrode unit and the internal electrode of each reference electrode unit is constant, and thus measurement errors are reduced between the measurement results when the internal electrode of each reference electrode unit is used.

In an example (not according to the present invention), the information on the state of the solution may include an ion concentration, the measuring unit may have a first ion sensitive field effect transistor and a second ion sensitive field effect transistor, the first part may have the first ion sensitive field effect transistor and the second part may have the second ion sensitive field effect transistor. Thus, even when a conventional ion sensitive field effect transistor (ISFET) type measuring device is used, the cycle of maintenance work is extended, which allows for a long-term measurement. The measuring unit composed of a small ISFET allows the measuring device <NUM> to be kept small.

According to the present disclosure, a measuring device that can measure a state of a solution over a long period of time and improve user convenience can be provided.

An embodiment of the present disclosure will be mainly described below with reference to the accompanying drawings. In the following drawings, for the sake of simplicity of description, the illustration of predetermined components is omitted as appropriate. For example, a solution L described later is omitted in <FIG>, <FIG>, <FIG>, <FIG> and <FIG>.

Configurations and functions of the measuring device <NUM> according to the first embodiment will be mainly described with reference to <FIG>.

<FIG> is a schematic diagram illustrating an example of configuration of the measuring device <NUM> according to the first embodiment. The measuring device <NUM> according to the first embodiment obtains the information on a state of a solution L. In the first embodiment, the "information on the state of the solution L" includes a pH concentration, i.e. a hydrogen ion concentration. The measuring device <NUM> according to the first embodiment has a plurality of electrode units used for the glass electrode type pH measurement. Referring to <FIG>, the measuring device <NUM> has a measuring unit <NUM> and a protection unit <NUM> attached to the measuring unit <NUM>.

The measuring unit <NUM> outputs a measurement signal associated with the state of the solution L. The measuring unit <NUM> has a first part P1 in a usable state and a second part P2 in a standby state for measurement. The "usable state" includes the state of the measuring unit <NUM> that can contribute to output of a measurement signal associated with the state of the solution L by coming into contact with the solution L. More specifically, in the first embodiment, the "usable state" includes the state of the measuring unit <NUM> that can contribute to output of a measurement signal based on the glass electrode type pH measurement. The "standby state for measurement" includes the state of the measuring unit <NUM> that is isolated from the solution L by the protection unit <NUM> and does not contribute to output of a measurement signal associated with the state of the solution L. More specifically, in the first embodiment, the "standby state for measurement" includes the state of the measuring unit <NUM> that does not contribute to output of a measurement signal based on the glass electrode type pH measurement.

The first part P1 of the measuring unit <NUM> has a pair including a glass electrode unit <NUM> and a first reference electrode unit <NUM>. The glass electrode unit <NUM> includes a glass thin film 11a that responds to hydrogen ions, an inner solution 11b with a known pH concentration, an internal electrode 11c for reading electric signals and a support 11d that supports the internal electrode 11c. The glass thin film 11a is attached to the end of the support 11d. The inner solution 11b is filled inside the support 11d. The inner solution 11b may include any solution, such as a pH <NUM> phosphate buffer solution. The internal electrode 11c is immersed in the inner solution 11b filled inside the support 11d.

The first reference electrode unit <NUM> has a liquid junction 12a, an inner solution 12b with a known pH concentration and a small liquid junction potential, an internal electrode 12c for reading electrical signals and a support 12d that supports the internal electrode 12c. The liquid junction 12a is disposed on the end of the support 12d and has a plurality of fine holes. The inner solution 12b is filled inside the support 12d. The inner solution 12b may include any solution such as a KCL solution. The inner solution 12b diffuses into the solution L via the liquid junction 12a. The internal electrode 12c is immersed in the inner solution 12b filled inside the support 12d.

In the glass electrode type pH measurement based on the first part P1, two different kinds of solutions are disposed inside and outside the support 11d with respect to the glass thin film 11a. That is, the inner solution 11b and the solution L are disposed. At this time, an electromotive force proportional to the difference in the pH concentration between the inner solution 11b and the solution L is generated on both surfaces of the glass thin film 11a. The internal electrode 11c immersed in the inner solution 11b generates an electromotive force corresponding to the electromotive force generated on both surfaces of the glass thin film 11a. On the other hand, the internal electrode 12c immersed in the inner solution 12b always generates a constant electromotive force while being in electrical contact with the solution L as the inner solution 12b diffuses into the solution L through the liquid junction 12a.

As described above, in the first part P1 of the measuring unit <NUM>, the inner solution 12b is diffused little by little from the liquid junction 12a to maintain the electrical connection between the internal electrode 12c of the first reference electrode unit <NUM> and the solution L. Therefore, the inner solution 12b gradually decreases over the measurement time as the pH concentration of the solution L is measured by the measuring device <NUM>. When the inner solution 12b is empty, measurement using the first part P1 of the measuring unit <NUM> becomes impossible. Therefore, in the conventional glass electrode type pH measuring device having no second part P2 and the protection unit <NUM>, due to the above described factors, the maintenance work including calibration and refill of the inner solution 12b occurs in a short period of time of about one to three months, for example. Although it is possible to increase the amount of inner solution 12b to extend the maintenance work cycle, in this case, the support 12d that contains the inner solution 12b will become large, and as a result, the whole glass electrode type pH measuring device becomes large. As described above, in the prior art, it is difficult to perform a long-term measurement using a glass electrode type pH measuring device while keeping the glass electrode type pH measuring device small, and the user convenience is low.

The measuring device <NUM> according to the first embodiment solves the above described problem, realizes measurement of the solution L over a long period of time, and improves the user convenience. Thus, the measuring device <NUM> has the second part P2 of the measuring unit <NUM> and the protection unit <NUM>.

The second part P2 of the measuring unit <NUM> has a second reference electrode unit <NUM>, which is different from a pair of the glass electrode unit <NUM> and the first reference electrode unit <NUM> in the usable state. The second reference electrode unit <NUM> has a liquid junction 13a, an inner solution 13b with a known pH concentration and a small liquid junction potential, an internal electrode 13c for reading electrical signals and a support 13d that supports the internal electrode 13c. The liquid junction 13a is disposed on the end of the support 13d and has a plurality of fine holes. The inner solution 13b is filled inside the support 13d. The inner solution 13b may include any solution such as a KCL solution. Diffusion of the inner solution 13b to the solution L via the liquid junction 13a is suppressed by the protection unit <NUM>. The internal electrode 13c is immersed in the inner solution 13b filled inside the support 13d.

The distance between the internal electrode 11c contained in the glass electrode unit <NUM> and the internal electrode 12c contained in the first reference electrode unit <NUM> may be the same as that between the internal electrode 11c and the internal electrode 13c contained in the second reference electrode unit <NUM>. In this manner, the distance between the internal electrode 11c of the glass electrode unit <NUM> and the internal electrode of each reference electrode unit is constant, and thus measurement errors are reduced between the measurement result when the internal electrode 11c and the internal electrode 12c are used and the measurement result when the internal electrode 11c and the internal electrode 13c are used.

<FIG> is a block diagram including the measuring device <NUM> and the solution L. Referring to <FIG>, the measuring device <NUM> has the measuring unit <NUM> including the glass electrode unit <NUM>, the first reference electrode unit <NUM> and the second reference electrode unit <NUM> and the protection unit <NUM>. In addition, the measuring device <NUM> has a voltage detector <NUM>, a controller <NUM>, a communication unit <NUM> and a memory <NUM>.

The voltage detector <NUM> includes any voltage sensor capable of detecting a voltage. The voltage detector <NUM> detects the difference in electromotive force, that is, a voltage, generated between the internal electrode 11c of the glass electrode unit <NUM> and the internal electrode 12c of the first reference electrode unit <NUM>. The voltage detector <NUM> switches the connection with the internal electrode 12c to the connection with the internal electrode 13c of the second reference electrode unit <NUM> in response to switching from the measurement based on the first reference electrode unit <NUM> to the measurement based on the second reference electrode unit <NUM> described later.

The controller <NUM> includes one or more processors. For example, the controller <NUM> includes a processor that enables processing related to the measuring device <NUM>. The controller <NUM> is connected to each component constituting the measuring device <NUM>, and controls and manages the entire measuring device <NUM> including each component. The controller <NUM> obtains the information on the state of the solution L on the basis of the measurement signal output from measuring unit <NUM>. More specifically, the controller <NUM> calculates the pH concentration of the solution L on the basis of the voltage signal from the measuring unit <NUM> obtained via the voltage detector <NUM>.

The communication unit <NUM> includes any communication interface corresponding to any communication protocol based on wire or wireless. The communication unit <NUM> may transmit the information on the state of the solution L obtained by the controller <NUM> to any external device. The communication unit <NUM> may receive a control signal for controlling an electrode heater <NUM> of the protection unit <NUM> described later from any external device.

The memory <NUM> includes any memory such as Hard Disk Drive (HDD), Solid State Drive (SSD), Electrically Erasable Programmable Read-Only Memory (EEPROM), Read-Only Memory (ROM) and Random Access Memory (RAM), and stores the information required for realizing operation of the measuring device <NUM>. The memory <NUM> may function as a main storage device, an auxiliary storage device, or a cache memory. The memory <NUM> is not limited to those built in the measuring device <NUM>, and may be an external memory connected by a digital input/output port such as a USB. The memory <NUM> stores, for example, the information on the state of the solution L obtained by the controller <NUM>.

<FIG> is an enlarged view of an end portion of the second reference electrode unit <NUM> in <FIG>. In <FIG>, the inner solution 13b and the internal electrode 13c contained in the support 13d are not illustrated. Configuration and function of the protection unit <NUM> will be mainly described with reference to <FIG>.

The protection unit <NUM> has a protection plate <NUM> that isolates the second part P2 of the measuring unit <NUM> from the solution L. More specifically, the protection plate <NUM> electrically isolates the second reference electrode unit <NUM> contained in the second part P2 from the solution L. The protection plate <NUM> is composed of at least one of biodegradable resin and acid-soluble resin including for example resin having a controlled molecular weight of acrylic acid type, phthalic acid type and the like. Configuration of the protection plate <NUM> is not limited thereto.

The protection plate <NUM> is attached, for example, to the end surface side of the support 13d of the second reference electrode unit <NUM> of the measuring unit <NUM> by adhesion with a heat-soluble adhesive <NUM>. The heat-soluble adhesive <NUM> is any resin having a melting point higher than the temperature of the solution L to be measured and lower than the temperature when heated by the electrode heater <NUM> described later.

An inner solution 13e with known properties is filled between the protection plate <NUM> and the liquid junction 13a of the second reference electrode unit <NUM>. The "properties" of the inner solution 13e include, for example, a pH concentration. The inner solution 13e may be the same solution as the inner solution 13b, a solution having the same pH concentration as and composed of components different from the inner solution 13b, or a solution completely different from the inner solution 13b.

In this manner, since the outside of the liquid junction 13a is protected by the inner solution 13e and the protection plate <NUM>, diffusion of the inner solution 13b to the solution L is suppressed. The inner solution 13e and the protection plate <NUM> suppress degradation of the internal electrode 13c, and maintain the second reference electrode unit <NUM> in the unused state which is the state before the second reference electrode unit <NUM> comes into contact with the solution L.

The protection unit <NUM> further has an electrode heater <NUM> that heats the attaching portion of the protection plate <NUM> to the measuring unit <NUM>. The heat-soluble adhesive <NUM> described above is provided to the attaching portion of the protection plate <NUM> to the measuring unit <NUM>, more specifically, the attaching portion of the protection plate <NUM> to the support 13d of the second reference electrode unit <NUM>. The electrode heater <NUM> is disposed near the heat-soluble adhesive <NUM>, and as illustrated in <FIG>, is connected to the controller <NUM> via a conduction wire <NUM> as illustrated in <FIG>. The electrode heater <NUM> heats the heat-soluble adhesive <NUM> on the basis of control by the controller <NUM>.

<FIG> is a schematic diagram illustrating time dependency of the pH concentration of the solution L obtained by the measuring device <NUM> in <FIG>. The vertical axis of <FIG> represents the pH concentration of the solution L and the horizontal axis of <FIG> represents the measurement time. The dashed lines illustrated in the example of the measurement graph of <FIG> represent drift of the measured value of the pH concentration of the solution L.

Referring to <FIG>, the measured value of the pH concentration of the solution L obtained by the measuring device <NUM> drifts in a fixed direction over the measurement time. When the actual pH concentration of the solution L changes, the measured value of the pH concentration of the solution L also changes correspondingly. However, even if the actual pH concentration of the solution L is fixed, the measured value of the pH concentration of the solution L shows a drift such that the measured value decreases at a constant rate. The user has some estimates on the pH concentration of the solution L, and the measuring device <NUM> is appropriately selected by the user so as to have a measurement range corresponding to the pH concentration of the solution L. That is, the measuring device <NUM> has a predetermined range that can be measured.

The controller <NUM> determines whether or not the measured value of the information on the state of the solution L exceeds a predetermined range that can be measured by the first part P1 of the measuring unit <NUM>. For example, due to the above described drift, the measured value of the information on the state of the solution L exceeds, at a certain measurement time, the lower limit value of a predetermined range that can be measured by the measuring device <NUM>. The measured value of the information on the state of the solution L takes a zero value or increases and goes off the scale when all of the inner solution 12b of the first reference electrode unit <NUM> flows to the solution L and the remaining amount of the inner solution 12b in the first reference electrode unit <NUM> becomes zero. At this time, the measured value of the information on the state of the solution L exceeds the lower limit value or the upper limit value in a predetermined range that can be measured by the measuring device <NUM>. When a foreign matter attaches to the surface of the glass thin film 11a, for example, the measured value of the information on the state of the solution L exceeds the lower limit value or the upper limit value in a predetermined range that can be measured by the measuring device <NUM> and keeps a specific pH concentration determined by the foreign matter.

When determining that the measured value of the information on the state of the solution L exceeds a predetermined range, the controller <NUM> heats the electrode heater <NUM> to remove the protection plate <NUM> from the measuring unit <NUM> through heating by the electrode heater <NUM>. At this time, the controller <NUM> obtains a measurement signal based on the second part P2. More specifically, the controller <NUM> switches the measurement using the glass electrode unit <NUM> and the first reference electrode unit <NUM> to the measurement using the glass electrode unit <NUM> and the second reference electrode unit <NUM>. In response to such a switching of measurement by the controller <NUM>, the voltage detector <NUM> switches the connection to the internal electrode 12c of the first reference electrode unit <NUM> to the connection to the internal electrode 13c of the second reference electrode unit <NUM>.

<FIG> is a flowchart illustrating an example of operation of the measuring device <NUM> in <FIG>. An example of operation of the measuring device <NUM> will be mainly described with reference to <FIG>.

In step S101, the measuring device <NUM> measures the state of the solution L based on the first part P1. More specifically, the controller <NUM> continuously obtains the information on the state of the solution L based on the voltage signal output from the measuring unit <NUM> using the glass electrode unit <NUM> and the first reference electrode unit <NUM>.

In step S102, the controller <NUM> determines whether or not the measured value of the information on the state of the solution L exceeds a predetermined range that can be measured by the first part P1 of the measuring unit <NUM>. If the controller <NUM> determines that the measured value of the information on the state of the solution L exceeds the predetermined range, the process proceeds to step S103. If the controller <NUM> determines that the measured value of the information on the state of the solution L does not exceed the predetermined range, the process goes back to step S101.

In step S103, the controller <NUM> stops measurement based on the first reference electrode unit <NUM>, heats the electrode heater <NUM> and detaches the protection plate <NUM> from the measuring unit <NUM> through heating by the electrode heater <NUM>. More specifically, the controller <NUM> melts the heat-soluble adhesive <NUM> that bonds the protection plate <NUM> to the support 13d by the electrode heater <NUM> to detach the protection plate <NUM>. When the protection plate <NUM> is composed of acid-soluble resin and the solution L is acidic, the thickness of the protection plate <NUM> may be determined by the measurement time when the measured value of the pH concentration of the solution L exceeds the lower limit value due to drift and the acid concentration of the solution L. More specifically, the thickness of the protection plate <NUM> is such that the protection plate <NUM> is not completely dissolved by the solution L before the measured value of pH concentration of the solution L exceeds the lower limit value due to drift. The detached protection plate <NUM> is dissolved by the solution L and disappears.

In step S104, the measuring device <NUM> measures the state of the solution L based on the second part P2. More specifically, the controller <NUM> continuously obtains the information on the state of the solution L based on the voltage signal output from the measuring unit <NUM> using the glass electrode unit <NUM> and the second reference electrode unit <NUM>.

According to the measuring device <NUM> of the first embodiment as described above, the state of the solution L can be measured over a long period of time, and the user convenience is improved. More specifically, the measuring unit <NUM> has, in addition to the first part P1, the second part P2 in the standby state for measurement. Thus, while the measuring device <NUM> is kept small, the cycle of maintenance work including calibration and refill of the inner solution 12b is extended, enabling a long-term measurement. Even if the measurement based on the first reference electrode unit <NUM> becomes impossible, the measurement can be continued based on the second reference electrode unit <NUM>. This allows for a long-term measurement with the measuring device <NUM> introduced into a biological body or a process from which the measuring device <NUM> is difficult to be removed. For example, when the measuring device <NUM> is used, a continuous measurement on a year-to-year basis is possible.

The information on the state of the solution L is transmitted to any external device by the communication unit <NUM>, thus the user can obtain the information on the state of the solution L even if the user is not at the site where the measuring device <NUM> is installed, for example, by using a communication method such as wireless communication.

Variations of the measuring device <NUM> according to the first embodiment will be mainly described below with reference to <FIG>.

<FIG> is a schematic diagram illustrating a first variation of the measuring device <NUM> in <FIG>. <FIG> illustrates the measuring unit <NUM> and the protection unit <NUM> of the measuring device <NUM> viewed from the bottom.

In the first embodiment, the measuring unit <NUM> is described as having one glass electrode unit <NUM> and two reference electrode units, but is not limited thereto. The measuring unit <NUM> may have three or more reference electrode units for one glass electrode unit <NUM>. Referring to <FIG>, the measuring unit <NUM> may further include a third reference electrode unit <NUM> and a fourth reference electrode unit <NUM>, for example, in addition to the glass electrode unit <NUM>, the first reference electrode unit <NUM> and the second reference electrode unit <NUM>.

In this case, the protection unit <NUM> similar to one that attached to the second reference electrode unit <NUM> may be attached also to the third reference electrode unit <NUM> and the fourth reference electrode unit <NUM>. That is, the first part P1 of the measuring unit <NUM> in the usable state has a pair of the glass electrode unit <NUM> and the first reference electrode unit <NUM>, which is the same as above. The second part P2 of the measuring unit <NUM> in the standby state for measurement further has, in addition to the second reference electrode unit <NUM>, the third reference electrode unit <NUM> and the fourth reference electrode unit <NUM>.

The distance between the internal electrode 11c contained in the glass electrode unit <NUM> and the internal electrode contained in each reference electrode unit may be the same. For example, the internal electrodes each contained in reference electrode units may be disposed concentrically with the internal electrode 11c contained in the glass electrode unit <NUM> as the center. This reduces the measurement error between the measurement results when using the internal electrode 11c and the internal electrode of each reference electrode unit because the distance between the internal electrode 11c of the glass electrode unit <NUM> and the internal electrode of each reference electrode unit is constant.

In the above embodiment, the protection plate <NUM> is described as being attached to the end surface side of the corresponding support through the heat-soluble adhesive <NUM>, but the attachment method of the protection plate <NUM> is not limited thereto. The protection plate <NUM> may be fixed by any method. For example, when it is necessary to fix a plurality of protection plates <NUM> as illustrated in <FIG>, instead of attaching to each corresponding support, a plurality of protection plates <NUM> may be attached to the end surface side of the support 10a that collectively contains each electrode unit through the heat-soluble adhesive <NUM>.

The protection plate <NUM> may be directly attached to the end surface of the corresponding support without using the heat-soluble adhesive <NUM>, instead of being attached to the end surface side of the corresponding support through the heat-soluble adhesive <NUM>. That is, the heat-soluble adhesive <NUM> is not necessary. At this time, the protection plate <NUM> is composed of any resin having a melting point higher than the temperature of the solution L to be measured and lower than the temperature when heated by the electrode heater <NUM>. In this manner, the protection plate <NUM> can be properly detached at a predetermined measurement time through control of the electrode heater <NUM> by the controller <NUM>.

<FIG> is a schematic diagram illustrating a second variation of the measuring device <NUM> in <FIG>. <FIG> illustrates the measuring unit <NUM> and the protection unit <NUM> of the measuring device <NUM> viewed from the bottom.

In the above, the measuring unit <NUM> is described as having one glass electrode unit <NUM>, but is not limited thereto. The measuring unit <NUM> may have two or more glass electrode units. For example, as illustrated in <FIG>, the measuring unit <NUM> may have another pair of a glass electrode unit <NUM> and a second reference electrode unit <NUM>, in addition to a pair of the glass electrode unit <NUM> and the first reference electrode unit <NUM>. At this time, the protection unit <NUM>, which is the same as the above described protection unit <NUM> attached to the second reference electrode unit <NUM>, may be attached to the glass electrode unit <NUM>. That is, the first part P1 of the measuring unit <NUM> in the usable state has a pair of the glass electrode unit <NUM> and the first reference electrode unit <NUM>, which is the same as above. The second part P2 of the measuring unit <NUM> in the standby state for measurement has a pair of the glass electrode unit <NUM> and the second reference electrode unit <NUM>. From mentioned above, the protection plate <NUM> suppresses deterioration of the glass electrode unit <NUM> in addition to the second reference electrode unit <NUM>. For example, it is possible to suppress adhesion of foreign matter to the surface of the glass thin film of the glass electrode unit <NUM>, and to suppress contamination of the glass thin film.

The distance between the internal electrode 11c contained in the glass electrode unit <NUM> and the internal electrode 12c contained in the first reference electrode unit <NUM> may be the same as the distance between the internal electrode contained in the glass electrode unit <NUM> and the internal electrode 13c contained in the second reference electrode unit <NUM>. Thus, the distance between each internal electrode of a pair of a glass electrode unit and a reference electrode unit is the same as that of a different pair. Therefore, the measurement error is reduced between measurement results when each pair of the internal electrode of the glass electrode units and the internal electrode of the reference electrode unit is used.

<FIG> is a schematic diagram illustrating a third variation of the measuring device <NUM> in <FIG>.

In the above, the protection plate <NUM> is described as being individually attached to each electrode unit contained in the second part P2 of the measuring unit <NUM>, but the attachment method of the protection plate <NUM> is not limited thereto. For example, as illustrated in <FIG>, as with <FIG>, when the second part P2 of the measuring unit <NUM> in the standby state for measurement has a pair of the glass electrode unit <NUM> and the second reference electrode unit <NUM>, the protection plate <NUM> may be attached collectively to the pair of the glass electrode unit <NUM> and the second reference electrode unit <NUM>.

As illustrated in <FIG> and <FIG>, even when a pair of the glass electrode unit <NUM> and the second reference electrode unit <NUM> are contained in the second part P2 of the measuring unit <NUM>, an inner solution 13e with known properties may be filled between the protection plate <NUM> and the second part P2 of the measuring unit <NUM>. This allows for calibration using the glass electrode unit <NUM> and the second reference electrode unit <NUM> until immediately before the controller <NUM> detaches the protection plate <NUM>. More specifically, before the protection plate <NUM> is detached, the measuring device <NUM> measures the inner solution 13e with known pH concentration using the glass electrode unit <NUM> and the second reference electrode unit <NUM>. In this manner, the controller <NUM> and the user can determine whether the known pH concentration and the measured value are the same or not. This allows for easy calibration of the measuring device <NUM>.

In the above, the inner solution 13e is described as being any solution, but is not limited thereto. The inner solution 13e may be any gel.

In the above description, measurement is switched when the controller <NUM> determines whether or not the measured value of the information on the state of the solution L exceeds the predetermined range that can be measured by first part P1 of measuring unit <NUM>. However, the determination method is not limited thereto. For example, the controller <NUM> may calculate the measurement life T in advance on the basis of the slope of the drift calculated by calibration before starting to use the measuring device <NUM> and the lower limit value of the predetermined range that can be measured. For example, the controller <NUM> may calculate the measurement life T in advance on the basis of the initial filling amount of the inner solution 12b of the first reference electrode unit <NUM> and the amount of the inner solution 12b flowing out from the liquid junction 12a per unit time.

The controller <NUM> may store the calculated measurement life T in a memory <NUM> and compare the operating time of the first part P1 of the measuring unit <NUM> with the measurement life T calculated in advance. For example, when determining that the measurement life T is not reached, the controller <NUM> continues measurement based on the first part P1 of the measuring unit <NUM>. For example, when determining that the measurement life T is reached, the controller <NUM> switches to the measurement based on the second part P2 of the measuring unit <NUM>.

For example, the controller <NUM> may measure the remaining amount of the inner solution 12b based on any sensor installed inside the support 12d in real time to determine whether or not the remaining amount of the inner solution 12b becomes zero. For example, when determining that the remaining amount of the inner solution 12b is not zero, the controller <NUM> continues measurement based on the first part P1 of the measuring unit <NUM>. For example, when determining that the remaining amount of the inner solution 12b is zero, the controller <NUM> switches to the measurement based on the second part P2 of the measuring unit <NUM>.

In the above description, the protection plate <NUM> is detached by controlling the electrode heater <NUM>. However, the removal method of the protection plate <NUM> is not limited thereto. For example, the protection unit <NUM> may not have the electrode heater <NUM>. In this case, the protection plate <NUM> being composed of biodegradable resin or acid-soluble resin, and is gradually decomposed or dissolved by the solution L. The protection plate <NUM> is formed to have a thickness such that the time during which the protection plate <NUM> is completely decomposed or dissolved and the measurement life T are substantially the same. The electrode heater <NUM> is not needed any more with the above described configuration. Thus consumption of a battery attached as a power source to the measuring device <NUM> is suppressed. Since the space for attaching the electrode heater <NUM> is saved, the measuring device <NUM> is downsized.

The measuring device <NUM> may further have a temperature sensor that is installed at any position such as an exterior wall of each support, for example, and measures the temperature of the solution L. This allows the controller <NUM> to correct the measured value of the information on the state of the solution L on the basis of the measured temperature of the solution L. Such a temperature sensor may be disposed between the protection plate <NUM> and the second part P2. This isolates the temperature sensor from the solution L during measurement based on the first part P1. Therefore, degradation of the temperature sensor is suppressed, and when the measurement based on the second part P2 is started, the temperature sensor can detect, in an unused state, the temperature.

(Second Example (not according to the present invention)) <FIG> is a schematic diagram illustrating an example of configuration of the measuring device <NUM> according to a second example. Configuration and function of the measuring device <NUM> according to the second example will be mainly described with reference to <FIG>.

In the description of the first embodiment, the information on the state of the solution L includes a pH concentration, and the measuring unit <NUM> has each electrode unit used for the glass electrode type pH measurement, but not limited thereto. In the measuring device <NUM> according to the second example, for example, the information on the state of the solution L includes ion concentration, and the measuring unit <NUM> may have a first ISFET <NUM> and a second ISFET <NUM>. The configuration of the measuring device <NUM> according to the second example is the same as that of the first embodiment other than the measuring unit <NUM>, and the above description for the first embodiment is applied as it is to the second example. The same reference signs are given to the same configurations as those in the first embodiment, and the description thereof will be omitted. The points different from the first embodiment will be mainly described.

Referring to <FIG>, the measuring unit <NUM> has a first ISFET <NUM> and a second ISFET <NUM>. The first ISFET <NUM> has a measurement electrode including a source electrode 71a and a drain electrode 71b and a reference electrode 71c. The first ISFET <NUM> has an ion sensitive film 71d disposed over the source electrode 71a and the drain electrode 71b. Similarly, the second ISFET <NUM> has a measurement electrode including a source electrode 72a and a drain electrode 72b and a reference electrode 72c. The second ISFET <NUM> has an ion sensitive film 72d disposed over the source electrode 72a and the drain electrode 72b.

The first part P1 of the measuring unit <NUM> has the first ISFET <NUM>. The second part P2 of the measuring unit <NUM> has the second ISFET <NUM>. The protection unit <NUM> is not attached to the first ISFET <NUM>, and the ion sensitive film 71d of the first ISFET <NUM> is in contact with the solution L. On the other hand, the protection unit <NUM> is attached to the second ISFET <NUM>, and an ion sensitive film 72d of the second ISFET <NUM> is isolated from the solution L. Therefore, the protection unit <NUM> suppresses deterioration including adhesion of foreign matters, alteration, scraping and the like in the ion sensitive film 72d of the second ISFET <NUM>.

The measuring unit <NUM> of the measuring device <NUM> according to the second example may further have some ISFETs having the same configuration as the second ISFET <NUM> to which the protection unit <NUM> is attached.

The measuring device <NUM> according to the second example as described above has the same effect as that of the first embodiment. In the measuring device <NUM> according to the second example, the measuring unit <NUM> is composed of a small ISFET. Therefore, even if the number of components of the second part P2 is increased as compared with that of the first embodiment, the measuring device <NUM> is kept small. The measuring device <NUM> according to the second example can extend the maintenance work cycle even when it is kept small, and allows for a long-term measurement.

(Third Example (not according to the present invention)) <FIG> is a schematic diagram illustrating an example of configuration of the measuring device <NUM> according to a third example. Configuration and function of the measuring device <NUM> according to the third example will be mainly described with reference to <FIG>.

In the measuring device <NUM> according to the third example, the information on the state of the solution L includes the ion concentration or the amount of chemical component composition, for example, and the measuring unit <NUM> may have a first metal thin film <NUM>, a second metal thin film <NUM>, a prism substrate <NUM> and a photo detector not illustrated. The configuration of the measuring device <NUM> according to the third example is the same as that of the first embodiment other than the measuring unit <NUM>, and the above description for the first embodiment is applied as it is to the configuration of the third example. The same reference signs are given to the same configurations as those in the first embodiment, and the description thereof will be omitted. The points different from the first embodiment will be mainly described.

The measuring unit <NUM> has the first metal thin film <NUM>, the second metal thin film <NUM>, the prism substrate <NUM> and a photo detector not illustrated. The first metal thin film <NUM> or the second metal thin film <NUM> is irradiated with a measurement light L1 via the prism substrate <NUM>. For example, the controller <NUM> obtains the light absorption spectrum of the solution L that is in contact with the first metal thin film <NUM> by detecting the measurement light L1 reflected on the surface of the first metal thin film <NUM> with a photo detector. The controller <NUM> analyzes the ion concentration or the chemical composition amount of each component in the solution L on the basis of the obtained light absorption spectrum.

The first part P1 of the measuring unit <NUM> has the first metal thin film <NUM>. The second part P2 of the measuring unit <NUM> has the second metal thin film <NUM>. The protection unit <NUM> is not attached to the first metal thin film <NUM>, and the first metal thin film <NUM> is in contact with the solution L. On the other hand, the protection unit <NUM> is attached to the second metal thin film <NUM>, and the second metal thin film <NUM> is isolated from the solution L. Therefore, in the second metal thin film <NUM>, the protection unit <NUM> suppresses deterioration including adhesion of foreign matters, alteration, scraping and the like.

The measuring unit <NUM> of the measuring device <NUM> according to the third example may further have some metal thin films having the same configuration as that of the second metal thin film <NUM> to which the protection unit <NUM> is attached.

The measuring device <NUM> according to the third example described above produces the same effect as that produced by the first embodiment. In the measuring device <NUM> according to the third example, unlike the first embodiment and the second example, there is no drift of the measurement signal. Therefore, the measuring device <NUM> can measure the state of the solution L over a long period of time as long as the metal thin film is not deteriorated due to factors including adhesion of foreign matters, alteration, scraping and the like. Even if the metal thin film deteriorates, the measuring unit <NUM> of the measuring device <NUM> has the second part P2, thus the measuring device <NUM> can extend the maintenance work cycle and allows for a long-term measurement. The above description is exemplary and is not limited thereto. The scope of disclosure is defined by the appended claims, not by the foregoing description.

For example, the shape, the disposition, the orientation, the number, and the like of each component described above are not limited to the contents illustrated in the above description and drawings. The shape, the disposition, the orientation, the number, and the like of each component may have any configuration as long as the function thereof can be realized.

Claim 1:
A measuring device (<NUM>) configured to measure a state of a solution, comprising:
a measuring unit (<NUM>) configured to output a measurement signal associated with the state of the solution;
a protection unit (<NUM>) attached to the measuring unit (<NUM>); and
a controller (<NUM>) configured to obtain information on the state of the solution on the basis of the measurement signal output from the measuring unit (<NUM>), wherein
the measuring unit (<NUM>) has:
a first part (P1) in a usable state that contributes to output of the measurement signal by coming into contact with the solution; and
a second part (P2) that is isolated from the solution by the protection unit and is in a standby state for measurement,
wherein:
the information on the state of the solution includes a pH concentration;
the measuring unit (<NUM>) has a glass electrode unit (<NUM>), a first reference electrode unit (<NUM>) and a second reference electrode unit (<NUM>) used for glass electrode type pH measurement;
the first part (P1) has a pair of the glass electrode unit (<NUM>) and the first reference electrode unit (<NUM>); and
the second part (P2) has the second reference electrode unit (<NUM>)
characterized in that:
the protection unit (<NUM>) has a protection plate (<NUM>) configured to isolate the second part (P2) of the measuring unit (<NUM>) from the solution; and
the protection plate (<NUM>) is composed of at least one of biodegradable resin and acid-soluble resin.