JP5046203B2 - Measuring device, fuel cell including the same, and measuring method - Google Patents

Description

  The present invention relates to a measurement device, a fuel cell including the same, and a measurement method, and more particularly to a technique for locally measuring the distribution of the amount of protic solvent in a membrane.

  In a functional material such as a film, the amount of solvent in the material may dominate the performance of the material. In the design and development of such materials, it is an important technical problem to locally measure the distribution of the amount of solvent. Examples of such functional materials include solid polymer electrolyte membranes used in fuel cells.

  In a fuel cell including a solid polymer electrolyte membrane, a gas containing water vapor is supplied as a fuel and an oxidant from a channel groove formed in a separator during operation. Due to the supply of the fuel and the oxidant, a distribution occurs in the amount of water in the solid polymer electrolyte membrane, and the distribution state changes with time. In order to improve the operating efficiency of such a fuel cell, it is important to accurately grasp the wet state of the solid polymer electrolyte membrane and control the supply of fuel and oxidant.

  As described above, the case of the fuel cell has been described as an example. If the distribution of the amount of the protic solvent contained in the membrane can be locally grasped on the spot, it is useful for evaluating the performance of the material.

  Here, as a technique for locally measuring the amount of the protic solvent at a specific portion of a sample, there is a conventional one described in Patent Document 1. In this document, a technique of locally applying a multi-echo method to a specific part of a sample, measuring a relaxation time constant by 1H-NMR, and locally measuring the amount of a protic solvent in the specific part of the sample. Is described. According to this technique, it is possible to measure the amount of local protic solvent at a specific location in a substance in a relatively short time using the NMR measurement result.

Other conventional techniques related to NMR measurement of samples include those described in Patent Documents 2 and 3.
Patent Document 2 describes that NMR measurement of a sample is performed using a U-shaped magnet and a solenoid coil.
Patent Document 3 describes a moisture distribution measuring device for a polymer film. In this method, an MRI image of a polymer film is acquired and a moisture distribution is acquired.

International Publication No. 2006/030743 Pamphlet JP 54-127785 A JP 2004-170297 A Tsushima S and two others, "Magnetic resonance imaging of the water distribution within a polymer electrolyte membrane in fuel cells", ELECTROCHEMICAL AND SOLID-STATE LETTERS, 7 (9), A269-A272, 2004 Takenaka Keigo, “Solid Polymer Electrolyte Water Electrolysis Technology and Its Applications”, Soda and Chlorine, Vol. 37, pp. 323-337 (1986)

  Here, if the distribution of the protic solvent when the protic solvent diffuses in the thickness direction and the plane direction in the film from a part of the film surface can be measured, it is useful for evaluating the characteristics of the film. Further, for example, the above-described solid polymer electrolyte membrane of a fuel cell is useful for optimal control of the operating state during battery operation.

  In the solid polymer electrolyte membrane of a fuel cell, water (protic solvent component) in the wet gas diffuses into the membrane from the region facing the separator groove. The amount of the protic solvent in the membrane is adjusted by the water supply from the wet gas and the water (protic solvent component) generated by the reaction between the fuel gas and the oxidant. Within the fuel cell separator, the concentration of fuel gas and oxidant is distributed between the inlet and outlet, and the amount of water (protic solvent component) produced in the membrane also depends on the active state of the catalyst. Has a spatial distribution. In addition, even when the amount of protic solvent in the membrane is adjusted by flowing a wet gas around the membrane, there is a difference in the concentration of the protic solvent at the inlet and outlet of the wet gas, and there is a difference between the protic solvent in the separator channel. A spatial distribution of the solvent concentration occurs. As a result, a spatial distribution is formed in the amount of protic solvent in the membrane.

  Therefore, we have developed a membrane that minimizes the amount of protic solvent in the membrane, and controlled the concentration of the protic solvent in the wet gas supplied so that the fuel cell can be operated with the optimum amount of protic solvent. It is necessary to do.

  For this purpose, a device for measuring the spatial distribution of the amount of protic solvent in the membrane is required. However, the conventional measuring device described above is used when the protic solvent diffuses into the membrane from a specific location of the membrane. However, it was not always suitable for measuring the amount of protic solvent in the membrane.

According to the present invention,
An apparatus for locally measuring the amount of a protic solvent at a specific location in a film using a nuclear magnetic resonance method,
A permanent magnet for applying a static magnetic field to the film;
An RF coil that applies an excitation oscillating magnetic field to a part of the film and acquires an echo signal corresponding to the excitation oscillating magnetic field;
From the intensity of the echo signal, a solvent amount calculation unit for calculating the amount of the protic solvent at a specific location of the membrane;
With
The permanent magnet is provided with a channel groove through which a fluid containing the protic solvent flows,
A measuring device is provided in which the film is provided in parallel to the flow path forming surface of the permanent magnet.

Moreover, according to the present invention,
A method of locally measuring the amount of the protic solvent at a specific location in the film by using a nuclear magnetic resonance method by disposing a film in parallel with the flow path forming surface of the permanent magnet in which the flow path groove is formed. There,
While flowing a fluid containing the protic solvent in the flow channel groove of the permanent magnet, a static magnetic field is applied to the film by a permanent magnet, and RF is applied to a part of the film placed in the static magnetic field. A first step of sequentially applying the excitation oscillating magnetic field a plurality of times using a coil and acquiring a plurality of echo signals corresponding to the excitation oscillating magnetic field;
A second step of determining the amount of the protic solvent at a specific location of the membrane from the intensity of the plurality of echo signals;
A measurement method is provided.

In the present invention, since a permanent magnet having a specific shape having a flow path forming surface is used, a static magnetic field is applied to the film, and a protic solvent is allowed to flow in the flow path groove to distribute the amount of protic solvent in the film. Can be formed. Then, the distribution of the protic solvent in the film is detected by applying an excitation oscillating magnetic field to the part of the film in which the distribution of the amount of the protic solvent is formed using an RF coil to obtain an echo signal. Can do.
In addition, since the film is arranged in parallel with the flow path forming surface of the permanent magnet, it is possible to reliably align the measurement location when performing the measurement using the permanent magnet having a specific shape and the RF coil.

Therefore, according to the present invention, for example, in the state where the protic solvent flowing through the flow channel is supplied into the membrane, or conversely, the proton solvent in the membrane is discharged from the membrane, The amount of the neutral solvent can be measured in situ.
In addition, a static magnetic field is applied to the membrane, and a protic solvent is allowed to flow through the channel groove to supply the protic solvent to the membrane, or conversely, the solvent is discharged from the membrane so that the membrane has a desired protic solvent. The amount can be adjusted. At that time, in order to confirm whether the amount of the protic solvent in the membrane is spatially uniform or a spatial distribution is formed, vibration for excitation is applied to a part of the membrane using an RF coil. An echo signal is acquired by applying a magnetic field, and a distribution of the amount of protic solvent can be obtained.
In addition, since it is possible to evaluate the diffusion behavior of the protic solvent in the in-plane direction of the membrane, for example, the evaluation of the membrane such as a simulation device for evaluating the distribution of the protic solvent in the solid polymer electrolyte membrane of the fuel cell The present invention can also be preferably applied to an apparatus. Further, as will be described later, the measuring apparatus of the present invention can be incorporated in, for example, a fuel cell.

  In addition, according to the present invention, measurement can be performed while flowing a fluid containing a protic solvent in the flow channel groove of the permanent magnet, and an echo signal can be acquired. This is not essential in the present invention, and the measurement may be performed without flowing a fluid. Examples of the protic solvent include water and alcohols such as methanol and ethanol.

Further, in this specification, the “echo signal” may be any signal that corresponds to the excitation oscillating magnetic field and functions as an NMR signal capable of calculating the T ₂ relaxation time constant.

Further, in this specification, the “static magnetic field” is a completely stable magnetic field as long as it is a time-stable magnetic field that can stably acquire an echo signal and a T ₂ relaxation time constant. There may not be, and there may be some variation within the range.

In the measurement apparatus of the present invention, the solvent amount calculation unit calculates a T ₂ relaxation time constant from the intensity of the echo signal, and the calculated protic solvent at a specific location of the membrane from the calculated T ₂ relaxation time constant. May be calculated.
In the measurement method of the present invention, the second step is a step of calculating a T ₂ relaxation time constant from the intensity of the echo signal, and a correlation between the amount of protic solvent in the membrane and the T ₂ relaxation time constant. And obtaining the amount of the protic solvent from the data and the T ₂ relaxation time constant calculated in the step of calculating the T ₂ relaxation time constant. .
By calculating the amount of the protic solvent from the T ₂ relaxation time constant, it is possible to further simplify the calibration operation of the measured value depending on the apparatus configuration.

  Here, in the vicinity of the surface of the permanent magnet, the magnitude of the static magnetic field changes along the normal direction of the surface. Further, when the flow path is provided on the surface of the permanent magnet, a spatial distribution different from the case where the flow path is not formed in the magnitude of the static magnetic field is generated in the upper part of the flow path forming surface. Since the resonance frequency in the measurement of the film changes depending on the strength of the static magnetic field at the measurement location, the relative position between the permanent magnet and the measurement location of the membrane is reliably adjusted in order to reliably acquire the echo signal. At the same time, it is important to reliably form an oscillating magnetic field for excitation at the measurement location in the film.

  In view of adjusting the distance between the permanent magnet and the film more precisely, for example, the flow path groove of the permanent magnet may include a plurality of groove portions arranged in parallel to each other. In this way, even when the measurement target is a flexible membrane, one of the membranes is formed at a specific interval from the flow path formation surface by the convex portions (flow path formation surface) formed between the plurality of grooves. The surface can be supported. Therefore, it is possible to keep the distance between the film and the flow path forming surface in the normal direction of the flow path forming surface in a specific size and stably hold the film near the flow path forming surface. At this time, one surface of the film may be in direct contact with the flow path forming surface of the permanent magnet, or a gap adjusting member made of a nonmagnetic material between the flow path forming surface and the film. It may be configured to intervene.

In the present invention, the RF coil may form the excitation oscillating magnetic field having an amplitude in a direction perpendicular to the extending direction of the groove portion in the flow path forming plane. In this way, among the upper regions of the flow path formation surface, particularly in the following regions (i) and (ii), a region having a uniform static magnetic field strength in a plane parallel to the flow path formation surface is provided. Can be formed.
(I) a region sandwiched between adjacent groove portions, along a direction in which the flow path forming surface extends, and (ii) a region above the single groove portion, in which the groove portion extends. The area along.

  In the above (i), the static magnetic field in the cross section perpendicular to the extending direction of the groove portion is maximized. Therefore, the region (i) is formed in a static direction in the extending direction of the groove portion in a plane parallel to the flow path forming surface. This is a region where the change of the magnetic field is small. In (ii) above, since the static magnetic field in the cross section perpendicular to the extending direction of the groove portion is minimized, the region (ii) is the extending direction of the groove portion in a plane parallel to the flow path forming surface. This is a region where the change of the static magnetic field is small.

  Therefore, by making the above (i) or (ii) as a measurement region, the local protic solvent amount can be measured with higher accuracy. In addition, if a plurality of regions having a uniform static magnetic field strength are formed, it is further preferable from the viewpoint of accurately performing multipoint measurement.

  When the above (i) or (ii) is used as the measurement region, for example, the RF coil includes a pair of coil portions, and the excitation oscillating magnetic field is formed in a region sandwiched between the pair of coil portions. , When viewed from above the flow path forming surface of the permanent magnet, a region sandwiched between the pair of coil portions is within a single groove portion forming region or a region sandwiched between adjacent groove portions. It can be set as the structure contained in.

  Among these, when (i) is used as the measurement region, the RF coil includes a first linear region including the first straight region from the viewpoint of further reliably suppressing the displacement of the flow path forming surface of the permanent magnet, the RF coil, and the film. A planar coil in which a coil portion and a second coil portion including a second linear region are connected, wherein the first coil portion and the second coil portion are conductively wound in a reverse direction, and the first linear region And the second linear region is arranged in parallel with the extending direction of the groove, and when viewed from above the flow path forming surface of the permanent magnet, between the first linear region and the second linear region. It is good also as a structure where the area | region pinched | interposed into is contained in the area | region pinched | interposed into the said adjacent groove part.

  By disposing the linear region of the RF coil on the upper part of the flow path forming surface of the permanent magnet, a region having a uniform static magnetic field strength in a plane parallel to the flow path groove forming surface can be set as the measurement region. In addition, since the linear region can be supported directly or indirectly by the flow path forming surface by arranging the linear region above the flow path forming surface, the gap between the flow path forming surface and the linear region can be further increased. This further suppresses the measurement of the amount of protic solvent more accurately.

  Further, when the above (ii) is used as a measurement region, the RF coil is a planar coil in which a first coil portion including a first linear region and a second coil portion including a second linear region are connected, In the first coil portion and the second coil portion, a conducting wire is reversely wound, and the first linear region and the second linear region are arranged in parallel to the extending direction of the groove portion, and the permanent magnet When viewed from above the flow path forming surface, a region sandwiched between the first straight region and the second straight region may be included in a single groove forming region.

  In the region above the groove, as will be described later with reference to FIG. 3B, the static magnetic field strength becomes maximum at a specific distance from the flow path formation surface in the normal direction of the flow path formation surface. By setting the region where the static magnetic field strength is maximized as the measurement region, the fluctuation of the static magnetic field during measurement can be further suppressed, and therefore the amount of the protic solvent can be measured more accurately.

  Further, from the viewpoint of more reliably suppressing the displacement of the flow path forming surface of the permanent magnet, the RF coil, and the film, the RF coil is disposed between the flow path forming surface of the permanent magnet and the film. A gap adjusting member having a specific thickness made of a nonmagnetic material is disposed between the flow path forming surface of the permanent magnet and the planar coil, and between the planar coil and the film. It may be.

  According to the present invention, a fuel cell comprising the above-described measuring device of the present invention is provided. This fuel cell may include, for example, a solid polymer electrolyte membrane as a membrane. At this time, since the amount of the local protic solvent in the solid polymer electrolyte membrane can be measured, the distribution of the protic solvent in the solid polymer electrolyte membrane can be directly obtained.

  In particular, in the measuring apparatus of the present invention, since the flow channel is provided on the surface facing the permanent magnet film, for example, at least one of the separators provided facing the fuel electrode or the oxidant electrode of the fuel cell. The part can be composed of a permanent magnet of the measuring device. As a result, the amount of local protic solvent in the solid polymer electrolyte membrane is measured while supplying fuel or an oxidant and further water vapor to the electrode of the fuel cell while simplifying the device configuration of the entire fuel cell. Can do.

  In this configuration, the flow path forming surface of the permanent magnet is disposed opposite to the fuel electrode of the fuel cell, and fuel gas may be supplied to the flow path groove, or the flow path of the permanent magnet The forming surface may be disposed to face the oxidant electrode of the fuel cell, and oxidant gas may be supplied to the flow channel.

As described above, according to the present invention, a static magnetic field is applied to a film by a permanent magnet having a specific shape having a flow path forming surface, and an RF coil is excited for vibration with respect to a part of the film placed in the static magnetic field. Since a plurality of echo signals corresponding to a magnetic field are applied and a distribution is formed in the amount of protic solvent in the membrane, the distribution state can be accurately detected.
In addition, by flowing a fluid containing fuel or an oxidant and a protic solvent through the flow channel, the amount of the protic solvent in the membrane is adjusted, and a plurality of echo signals corresponding to this are obtained, It is possible to accurately detect the spatial distribution state of the amount of the protic solvent.
Thereby, the local amount of the protic solvent in the membrane can be measured in-situ while flowing a fluid containing the protic solvent through the channel groove of the permanent magnet.
In addition, the diffusion characteristics of the amount of protic solvent in the plane direction of the membrane can be evaluated.

  Embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same reference numerals are given to the same components, and the description will be omitted as appropriate.

In the following embodiments, the amount of protic solvent in the film is calculated using a nuclear magnetic resonance (NMR) method.
In the NMR method, the number density and relaxation time constant can be obtained by detecting the movement of nuclear magnetization as an NMR signal by the spin resonance phenomenon of a nucleus placed in a magnetic field. Examples of the physical quantity corresponding to the atomic number density include the water content in the polymer electrolyte membrane. As relaxation time constants, for example, there are T ₁ and T ₂ relaxation time constants. If the CPMG method is used, a T ₂ (CPMG) relaxation time constant strongly dependent on the water content can be obtained. Hereinafter, the case where the excitation oscillating magnetic field is applied as a high-frequency pulse sequence using the CPMG method will be described as an example.

  In addition, the measurement apparatus of the present invention includes a specific-shaped permanent magnet having a channel groove and an RF detection coil (also simply referred to as “RF coil”) that applies an excitation oscillating magnetic field. Therefore, in the following, first, specific examples of the permanent magnet and the RF coil constituting the measuring device in the first embodiment and the second embodiment will be shown. And in 3rd embodiment, the specific structure of the measuring apparatus which combined the said permanent magnet and RF coil is demonstrated. Furthermore, in 4th embodiment, the specific example of a fuel cell provided with the measuring apparatus as described in 3rd embodiment is shown.

(First embodiment)
In the present embodiment, the configuration of the permanent magnet used in the third embodiment will be described.
Fig.1 (a) and FIG.1 (b) are figures which show the structure of the permanent magnet of this embodiment. FIG.1 (b) is AA 'sectional drawing of Fig.1 (a).
In addition, although an example of the shape and dimension of the permanent magnet 113 is shown in FIGS. 1A and 1B, the shape and dimension of the permanent magnet 113 are not limited to those illustrated. In FIG. 1, unless otherwise specified, the unit of dimension is mm. FIG. 2 is a diagram showing a permanent magnet manufactured with the dimensions shown in FIG.

  The permanent magnet shown in FIGS. 1 and 2 is made of a magnetic material and is a member that applies a static magnetic field to a film to be measured in a protic solvent amount measuring device. Examples of the material of the permanent magnet 113 include neodymium, iron, and boron-based materials such as NEOMAX (registered trademark) manufactured by NEOMAX.

  1A and 1B exemplify a configuration in which the permanent magnet 113 is formed by joining blocks made of a plurality of magnetic materials. However, the permanent magnet 113 is made up of a single block and joined. The structure which does not have a part may be sufficient.

  The permanent magnet 113 is provided with a flow path forming surface, and a flow path groove 101 through which a fluid containing a protic solvent flows is provided on the flow path forming surface. The film to be measured is provided in parallel to the flow path forming surface of the permanent magnet 113. The permanent magnet 113 applies the static magnetic field in the normal direction of the film.

In the following description, the flow path forming surface of the permanent magnet 113 corresponds to the top surface of the convex portion 103, and the groove portion included in the flow channel groove 101 corresponds to the concave portion 105.
The flow path forming surface of the permanent magnet 113 includes an uneven surface constituted by a plurality of recesses 105 and protrusions 103 provided alternately and continuously. The plurality of convex portions 103 and the plurality of concave portions 105 all extend in parallel with each other. Both of the convex portion 103 and the concave portion 105 extend linearly in one specific direction (x direction in the figure).

Further, the top surfaces of the plurality of convex portions 103 are all located in the same plane, and the bottom surfaces of the plurality of concave portions 105 are all located in the same plane parallel to the top surface of the convex portion 103. Yes. FIG. 1A illustrates a case where the top surface of the convex portion 103 and the bottom surface of the concave portion 105 are both horizontal to the xy plane.
Further, in the AA ′ cross section, the width of the plurality of convex portions 103 (y direction) and the width of the plurality of concave portions 105 are both substantially equal.

When the permanent magnet 113 having such a configuration is arranged in the space, the static magnetic field strength in the in-plane direction (xy plane in the figure) parallel to the flow path forming surface is uniform on the upper part of the convex part 103 and the upper part of the concave part 105. Areas are formed.
Among these, in the upper part of the convex portion 103, a region having a uniform static magnetic field strength in a plane parallel to the flow path forming surface is formed along the extending direction of the convex portion 103, and It is formed over a specific width in the width direction.
In addition, in the upper part of the recess 105, a region having a uniform static magnetic field strength in a plane parallel to the flow path forming surface is formed along the extending direction of the recess 105, and in the width direction of the recess 105, It is formed over a specific width.
These regions are suitably used as measurement regions when performing local NMR measurement of the film.

Hereinafter, it will be described more specifically that a uniform static magnetic field plane is formed on the top of the convex portion 103 and the concave portion 105 along the extending direction.
The inventor evaluated the spatial distribution of the static magnetic field intensity using the permanent magnet shown in FIG. A Gauss meter (TM-501 manufactured by KANETEC) was used as a measuring device. For the static magnetic field strength, only the z-direction component was measured. 3, 4, and 5, the measured static magnetic field intensity (z-direction component) in the z-axis direction (normal direction of the flow path forming surface), the y-axis direction (cross-sectional direction of the groove), and x The distribution of the position in the axial direction (extending direction of the groove) is shown. Here, the center of the central row of the five convex portions of the permanent magnet shown in FIG. 2 is set to y = 0 mm.

FIGS. 3A and 3B are diagrams for explaining the measurement results of the position distribution in the z-axis direction of the static magnetic field intensity H ₀ (z-direction component). FIGS. 4A and 4B are diagrams illustrating measurement results of the position distribution in the y-axis direction of the static magnetic field strength H ₀ (z-direction component).

  From FIG. 3B and FIG. 4B, in the region above the convex portion 103 (y = 0 mm), the magnetic field strength is strongest on the magnet surface (z = 0 mm), and the distance from the magnet increases, that is, z increases. It can be seen that the magnetic field strength decreases. On the other hand, in the upper region of the recess 105 (y = 6.35 mm), the magnetic field strength becomes maximum when z = 5 to 6 mm, and thereafter, the magnetic field strength decreases as the distance from the magnet increases.

  Further, in the measurement using the permanent magnet 113, from the viewpoint of suppressing abrupt fluctuations in the magnetic field strength in the z direction, the height is 1 / depth of the depth of the recess 105 in the region above the recess 105 on the flow path forming surface. Four or more positions, preferably one third or more positions can be set as the measurement region. Moreover, although there is no restriction | limiting in particular in the upper limit of the height of a measurement area | region, For example, from FIG.3 (b), about the height of about 1.5 times the depth of the recessed part 105, the rapid fluctuation | variation of the static magnetic field of az direction is carried out. Can be suppressed.

  Further, as shown in FIG. 3B, a region where the magnetic field strength is maximized is formed above the recess 105. The region where the magnetic field intensity becomes maximum is not formed on the plane of the permanent magnet having no flow channel 101 and is a phenomenon peculiar to the permanent magnet 113 having the flow channel 101. In the vicinity of the region where the magnetic field strength at the upper part of the recess 105 is maximized, for example, in the region having a height of 1/3 or more and 3/2 or less of the depth of the recess 105, in the in-plane direction horizontal to the flow path forming surface. Since the amount of change in the static magnetic field strength is even smaller, the change in the measured value due to the displacement of the measurement position can be further suppressed when performing NMR measurement of the film.

  Further, from FIG. 3B, the magnetic field strength is about 0.2 to 0.3 Tesla even at a position away from the magnet, for example, z> 10 mm. As shown in the examples described later, NMR measurement is sufficiently possible with such a magnetic field strength.

  Further, from FIG. 4B, the magnetic field strength is a maximum value at the position of the central axis (y = 0 mm) of the convex portion 103 and the central axis (y = 6.35 mm) of the concave portion 105 regardless of the position of z. And the minimum value. In the vicinity of these two y positions, the magnetic field is flat, and in this embodiment, this region is a position where NMR measurement is performed.

Figure 5 (a) ~ FIG. 5 (c) is a diagram illustrating the measurement results of the positional distribution of the x-axis direction of the static magnetic field strength H ₀ (z-direction component). FIG. 5A shows a cross section of the permanent magnet 113 with respect to the extending direction of the convex portion 103 and the concave portion 105, and FIG. 5B shows the permanent magnet 113 perpendicular to the extending direction of the convex portion 103 and the concave portion 105. A cross section is shown.

FIG. 5C is a diagram showing a position distribution in the x-axis direction of the static magnetic field strength H ₀ (z-direction component). That is, FIG. 5C shows the magnetic field strength in the groove direction. From FIG. 5C, it can be seen that the magnetic field strength is substantially uniform along the extending direction in both the upper portion of the convex portion 103 and the upper portion of the concave portion 105. Further, it can be seen that the nuclear magnetic resonance frequency of the film at the time of NMR measurement is uniform in the extending direction of the groove, that is, in the extending direction of the convex portion 103 and the concave portion 105.

  From the above results, for example, by arranging the film and the RF coil so that the first region 107 and the second region 109 shown in FIG. 6 are the NMR measurement regions, the static magnetic field strength at the time of measurement can be appropriately selected. Since the spatial distribution of the static magnetic field can also be appropriately selected, the nuclear magnetic resonance frequency to be measured and the measurement region can be adjusted, and NMR measurement can be performed with higher accuracy in accordance with the apparatus and the measurement sample.

  FIG. 6 is a perspective view showing the first region 107 and the second region 109 that are easily subjected to NMR measurement by the permanent magnet 113 of the present embodiment. In FIG. 6, the first region 107 is a region above the convex portion 103 in the vicinity of y = 0 mm, and the first region 107 is formed along the extending direction of the convex portion 103. The second region 109 is an upper region of the recess 105 in the vicinity of y = 6.35 mm, and is formed along the extending direction of the recess 105.

  As shown in FIG. 6, when viewed from the upper part of the flow path forming surface of the permanent magnet 113, the static magnetic field strength is uniform in the plane parallel to the flow path forming surface (the first region 107 and the second region). The region 109) is formed as a cylindrical region on the upper portion of the convex portion 103 and the upper portion of the concave portion 105, respectively.

  In addition, in the cross-sectional view in the extending direction of the recess 105, the widths of the first region 107 and the second region 109 vary depending on the position in the z direction as shown in FIG. As for one region 107, a region having about ¼ of the width of the convex portion 103 on both sides from the center (maximum point) of the convex portion 103 can be a region where the spatial nonuniformity of the static magnetic field is small. . In addition, as for the second region 109, a region having about 1/4 of the width of the concave portion 105 on both sides from the center (minimum point) of the concave portion 105 may be a region having a small static magnetic field non-uniformity. it can.

  Moreover, the permanent magnet 113 of this embodiment is a shape provided with an uneven surface, and the NMR measurement is performed by disposing the uneven surface in parallel with the film. For this reason, for example, the permanent magnet 113 can be incorporated into the fuel cell as a separator (gas flow path portion). By using the permanent magnet 113 as a fuel cell separator, it is possible to measure the amount of the protic solvent in the electrolyte layer of the fuel cell such as a solid polymer electrolyte membrane. Note that a configuration example of a fuel cell including a measuring device having a permanent magnet 113 will be described in more detail in the fourth embodiment.

In the present embodiment, the configuration in which a plurality of recesses 105 (grooves) are independently provided on the flow path forming surface of the permanent magnet 113 is illustrated, but the flow path groove 101 has a plurality of shapes in cross-sectional view. As long as the convex portion 103 and the concave portion 105 are repeatedly provided, a plurality of groove portions may be connected in plan view. Even in the case where a plurality of grooves are in communication, if the permanent magnet has the cross-sectional shape described above with reference to FIGS. 3 to 6, the static magnetic field distribution conforming to the static magnetic field distribution shown in FIGS. Since it is formed, it can be used as a permanent magnet used for measuring the distribution of the amount of protic solvent in the film.
Moreover, in this embodiment, although the structure which the some flow part contained in the flow-path groove extended mutually parallel was illustrated, the planar shape and planar arrangement | positioning of a flow path are not restricted to this.

(Second embodiment)
In the present embodiment, the configuration of the RF coil used in the measurement apparatus of the third embodiment will be described. In the following description, the case where the NMR measurement target film is a solid polymer electrolyte film will be described as an example.

As described above with reference to FIG. 6 in the first embodiment, in the permanent magnet 113 used in the apparatus for measuring the amount of protic solvent, the direction perpendicular to the top surface of the convex portion 103 and the bottom surface of the concave portion 105 (z direction, A static magnetic field H ₀ is formed in the upward direction in the figure. In addition, in the upper region of the convex portion 103 and the concave portion 105, a region in which NMR measurement is more easily performed is formed along these extending directions.

  Therefore, in the present embodiment, a planar coil configured to form an excitation oscillating magnetic field in the first region 107 or the second region 109 is used as the RF coil. Hereinafter, the planar coil forms an oscillating magnetic field for excitation in a direction perpendicular to the static magnetic field, specifically, excitation having an amplitude in the direction in the flow path forming plane and perpendicular to the extending direction of the groove. An example of forming an oscillating magnetic field will be described.

  FIG. 8 is a diagram showing the configuration of the planar coil. The planar coil 114 shown in FIG. 8 includes a pair of coil parts (a first coil part 119 and a second coil part 121) and forms an excitation oscillating magnetic field in a region sandwiched between the pair of coil parts. Further, for example, when the planar coil 114 is viewed from the upper part of the flow path forming surface of the permanent magnet 113, the region sandwiched between the pair of coil portions is formed in a single groove portion forming region or adjacent groove portions. Used in an arrangement contained within the sandwiched area.

  In FIG. 8, the first coil portion 119 is a coil portion including the first straight region 123 and the conducting wire is wound in a right-handed manner, and the second coil portion 121 includes the second straight region 125 and the conducting wire is provided in a left-handed manner. Although the example which is the coil part wound was shown, how to wind the conducting wire of each coil part is not restricted to this. When current flows in the same direction in the first linear region 123 and the second linear region 125, an excitation oscillating magnetic field perpendicular to the linear region and parallel to the coil surface is formed between these linear regions.

  More specifically, the planar coil 114 is a Double-D type (also referred to as an 8-shaped coil or a butterfly coil). The Double-D type coil has a shape in which a conducting wire is wound in a semicircular shape and two coils are opposed to each other, and the two semicircular strings correspond to straight portions, and the strings are arranged in parallel to each other. .

FIG. 8 shows specific dimensions of the planar coil 114 and the LC resonance circuit. The resonance frequency of this coil is, for example, 13.07 MHz. The manufactured coil has a chlority factor Q value of 25. The dimension of the illustrated planar coil 114 is an example designed according to the dimension of the permanent magnet 113 shown in FIG. 1, and is not limited to this dimension.
FIG. 9 is a view showing a coil manufactured based on the design of FIG.

In the planar coil 114 configured by combining coil portions having two linear regions parallel to each other like a Double-D type coil, a region between the first linear region 123 and the second linear region 125, that is, two An oscillating magnetic field H ₁ is formed around the axis of symmetry of the semicircular coil. As shown in the analysis results of the examples described later, the periphery of this axis of symmetry is the detection region (measurement region) of the planar coil 114. Therefore, if the two first regions 107 or the second regions 109 of the permanent magnet 113 shown in FIG. 6 are superimposed on the detection region of the planar coil 114, the static magnetic field H ₀ and the oscillating magnetic field H ₁ are perpendicular to each other. Therefore, the region in the vicinity of the symmetry axis of the pair of coil portions is a more preferable region for performing NMR measurement.
Note that the spatial distribution of the oscillating magnetic field formed by the planar coil 114 will be described in more detail in an embodiment described later.

  By using the planar coil 114 of this embodiment in combination with the first embodiment, the static magnetic field forms a uniform region (first region 107, second region 109) in the plane, and these regions are formed. In addition, the excitation oscillating magnetic field can be reliably formed. Then, a film is disposed on the first region 107 or the second region 109, and an echo signal is acquired by using the region above the first region 107 or the second region 109 as a measurement region. Accuracy can be improved.

  In addition, since a plurality of planar coils such as the planar coil 114 need not be stacked, the structure is suitable for multipoint measurement in the thickness direction of the film. When a plurality of planar coils 114 are arranged so as to overlap each other when viewed from the upper part of the flow path forming surface of the permanent magnet 113, the distribution of the amount of protic solvent in the thickness direction at a specific location within the surface of the membrane is measured. Can do. Further, by using one planar coil 114, it is possible to perform measurement at different positions in the film thickness direction. The resonance frequency in NMR measurement varies depending on the strength of the static magnetic field. With this magnet, the magnetic field strength changes in the thickness direction of the film, and the resonance frequency changes accordingly. NMR measurement can be performed by selecting a measurement position in the thickness direction of the film depending on the difference. Due to this difference in resonance frequency, the interference of NMR signals can also be suppressed.

In addition, if a plurality of planar coils 114 are arranged side by side in the first region 107 or the second region 109, it becomes possible to perform multipoint measurement in the same static magnetic field, and therefore, measurement of the distribution in the in-plane direction of the film. In addition, the region is suitable for a case where the amount of the protic solvent is measured a plurality of times in the region where the membrane faces the specific recess 105.
In addition, since the magnitude of the static magnetic field in a plane parallel to the flow path forming surface is different between the upper part of the convex part 103 and the upper part of the concave part 105, if the planar coil 114 is arranged in each of these, the signal interference Can be more effectively suppressed.

  Further, as will be described later in the fourth embodiment, when the permanent magnet 113 is used as a fuel cell separator, an RF detection coil is sandwiched between the polymer electrolyte membrane and the separator (the gas diffusion layer is on the separator side). Is desirable.

In this respect, a cylindrical shape such as a solenoid type coil has a three-dimensional shape and cannot be sandwiched in the gap.
On the other hand, if the RF detection coil is planar (sheet-like), it can be easily sandwiched in the gap. In this embodiment, by using the planar coil 114 as the RF coil, it is easy to incorporate into the fuel cell even when measuring the solid polymer electrolyte membrane using the permanent magnet 113 as the separator of the fuel cell. The enlargement of the whole fuel cell can be suppressed.

  In addition, although the case where the planar coil 114 is a Double-D type coil having two half-moon-shaped coil sections has been described above, the planar coil 114 is a first coil section including the first linear region 123. 119 and the 2nd coil part 121 provided with the 2nd linear area | region 125 should be included, and the conducting wire of these coil parts should just be the structure of reverse winding, and the planar shape of a coil part is not restricted to a half-moon shape. For example, the planar shape of the two coil portions may be a polygon such as a square, a rectangle, or a triangle.

  The planar coil 114 is not particularly limited in size as long as it is configured to apply an excitation oscillating magnetic field to a part of the film, but can be made smaller than the film to be measured, for example. Further, the planar coil 114 can be made smaller than the flow path forming surface of the permanent magnet 113, for example. More specifically, in a cross-sectional view with respect to the extending direction of the groove portion of the permanent magnet 113, the width of the planar coil 114 is larger than the total width of the convex portion 103 and the concave portion 105 of the permanent magnet 113, and the convex portion 103, You may make it smaller than the sum total of the width | variety of the recessed part 105 and the convex part 103. FIG. In this way, when the planar coil 114 is disposed between the flow path forming surface of the permanent magnet 113 and the film, the spacing in the z direction between the planar coil 114, the permanent magnet 113, and the film is more reliably regulated. can do.

(Third embodiment)
The present embodiment relates to a measuring apparatus including the permanent magnet 113 described in the first embodiment and the RF coil (planar coil 114) described in the second embodiment.

  FIG. 10 is a diagram illustrating a configuration of the measurement apparatus of the present embodiment. A measuring apparatus 100 shown in FIG. 10 is an apparatus that locally measures the amount of a protic solvent at a specific location in a film using a nuclear magnetic resonance method. Hereinafter, the case where the protic solvent is water will be described as an example.

The measuring device 100 is
A permanent magnet 113 for applying a static magnetic field in a specific direction to the film 115 to be measured;
An excitation oscillating magnetic field is applied to the film 115 in a direction perpendicular to the static magnetic field, an echo signal corresponding to the oscillating magnetic field for excitation is acquired, and T ₂ relaxation is obtained from the intensity of the echo signal. A time constant is calculated, and from the calculated T ₂ relaxation time constant, a solvent amount calculation unit (solvent amount calculation unit 124) that calculates a protic solvent amount at a specific location in the membrane 115
Is provided.

The permanent magnet 113 is made of a magnetic material as described above in the first embodiment. The film 115 is disposed in parallel to the flow path forming surface of the permanent magnet 113. The permanent magnet 113 applies a static magnetic field in the thickness direction of the film 115. An excitation high-frequency pulse is applied to the film 115 in a state where the static magnetic field is applied, and the T ₂ relaxation time constant is measured.

  The planar coil 114 applies a high frequency pulse for excitation. More specifically, the planar coil 114 is the Double-D type RF detection coil described above in the second embodiment. FIG. 10 shows an example in which two linear regions of the planar coil 114 are arranged on the upper portion of the concave portion 105. However, the arrangement of the planar coil 114 is not limited to this, for example, on the upper portion of the convex portion 103. You may arrange.

  FIG. 11 is a cross-sectional view showing in more detail the arrangement of the permanent magnet 113, the planar coil 114, and the film 115 in the measuring apparatus 100 shown in FIG. FIG. 11 illustrates the case where the membrane 115 is a solid polymer electrolyte membrane 117.

The planar coil 114 is disposed above the flow path forming surface of the permanent magnet 113, for example, between the flow path forming surface (uneven surface) of the permanent magnet 113 and the solid polymer electrolyte membrane 117.
As shown in FIG. 11, in the measuring apparatus 100, non-periphery is provided between the convex portion 103 of the permanent magnet 113 and the planar coil 114 and between the planar coil 114 and the solid polymer electrolyte membrane 117. An interval adjusting member (a first spacer 127 and a second spacer 129) having a specific thickness made of a magnetic material is disposed. The direction of the static magnetic field H ₀ created by the permanent magnet 113 and the direction of the oscillating magnetic field H ₁ created by the Double-D type coil (planar type coil 114) are perpendicular to each other.

Further, in the Double-D type RF detection coil, the echo signal intensity changes when the distance in the z direction from the solid polymer electrolyte membrane 117 is changed. This is because the intensity distribution of the oscillating magnetic field H ₁ and the reception sensitivity of the coil change depending on the distance. For example, according to the study of the present inventor, as will be described later in the embodiment, in the Double-D coil shown in FIG. 9, the distance at which the maximum echo signal intensity can be obtained is about 1 mm. By experimentally acquiring the intensity distribution of the oscillating magnetic field H ₁ in advance, the positions of the Double-D type detection coil and the solid polymer electrolyte membrane 117 can be determined as shown in FIG.

As shown in FIG. 11, in the measuring apparatus 100, a first spacer 127 having a specific thickness is disposed between the permanent magnet 113 and the planar coil 114, thereby holding them at a specific interval. Further, by arranging the second spacer 129 between the planar coil 114 and the solid polymer electrolyte membrane 117, these are held at a specific interval. By using these separators to adjust the concave / convex surface of the permanent magnet 113, the planar coil 114 installation surface, and the relative position (z direction) of the solid polymer electrolyte membrane 117, the thickness of the solid polymer electrolyte membrane 117 is adjusted. The reception position of the echo signal can be improved in the measurement region by precisely adjusting the measurement position. Therefore, local T ₂ measurement of the solid polymer electrolyte membrane 117 can be performed with high sensitivity and accuracy.

  In addition, from the viewpoint of further reliably suppressing the deflection of the solid polymer electrolyte membrane 117, the third spacer 135 is provided on the upper portion of the convex portion 103 where the planar coil 114 is not disposed, together with the third spacer, You may fill the space | gap 137 formed between the 3rd spacer 135 and the solid polymer electrolyte membrane 117 with the bead-shaped space | interval adjustment member (not shown). In this way, the distance between the permanent magnet 113 and the solid polymer electrolyte membrane 117 can be adjusted more precisely, and the solid polymer electrolyte membrane 117 can be held in that state. At this time, the thickness of the third spacer 135 is set to be smaller than the total thickness of the first spacer 127, the second spacer 129, and the planar coil 114, and more specifically, the first spacer The thickness is approximately the same as the total thickness of the spacer 127 and the second spacer 129.

  Further, in the arrangement shown in FIG. 11, for example, a solid polymer electrolyte membrane (PEM) for a fuel cell is held by a separator (permanent magnet 113), and a Double-D type RF detection coil (planar coil 114) is placed in the gap therebetween. Since it can be easily applied to the installation mode, the measuring apparatus 100 is also preferably used for local moisture measurement of the solid polymer electrolyte membrane of the fuel cell. Thus, the measuring apparatus 100 of this embodiment can be used as an apparatus for evaluating the local water content of a film such as a solid polymer electrolyte membrane.

In addition, the result of having performed NMR measurement of various samples with the arrangement shown in FIG. 11 and the calculated T ₂ (CPMG) value will be described later in Examples.

Returning to FIG. 10, the configuration of the measuring apparatus 100 will be further described.
The planar coil 114 may be single or plural. If the number is plural, the moisture content distribution in the film 115 can be measured. In this case, if it is arranged two-dimensionally along the surface of the film 115, a two-dimensional moisture content distribution on the film surface can be obtained. Further, if the film 115 is three-dimensionally arranged, the three-dimensional moisture content distribution in the film can be obtained.

  The oscillating magnetic field (exciting oscillating magnetic field) applied by the planar coil 114 is generated by the cooperation of the RF oscillator 102, the modulator 104, the RF amplifier 106, the pulse control unit 108, the switch unit 161, and the planar coil 114. That is, the excitation high-frequency RF transmitted from the RF oscillator 102 is modulated by the modulator 104 based on the control by the pulse control unit 108 and becomes a pulse shape. The generated RF pulse is amplified by the RF amplifier 106 and then sent to the planar coil 114. The planar coil 114 applies this RF pulse to a specific part of the film. The planar coil 114 detects an echo signal of the applied RF pulse. This echo signal is amplified by the preamplifier 112 and then sent to the phase detector 110. The phase detector 110 detects this echo signal and sends it to the A / D converter 118. The A / D converter 118 performs A / D conversion on the echo signal and then sends it to the arithmetic unit 130.

The switch part 161 is provided in a branch part that connects the planar coil 114, the RF signal generation part, and the echo signal detection part.
The RF signal generation unit includes an RF oscillator 102, a modulator 104, and an RF amplifier 106, and generates an RF signal that causes the planar coil 114 to generate an oscillating magnetic field for excitation. The echo signal detection unit includes a preamplifier 112, a phase detector 110, and an A / D converter 118. The echo signal detection unit detects an echo signal acquired by the planar coil 114 and sends the echo signal to the arithmetic unit 130.

  The switch unit 161 has a first state in which the planar coil 114 and the RF signal generation unit (RF amplifier 106) are connected, and a planar coil 114 and the echo signal detection unit (phase detector 110). It has a function of switching the second state. That is, the switch unit 161 serves as such a “transmission / reception switching switch”.

  By providing the switch part 161 at the branch part, the loss of the excitation high-frequency pulse signal applied from the planar coil 114 to the film 115 is reduced, and as a result, the pulse angles of the 90 ° pulse and the 180 ° pulse are accurately set. It becomes possible to control. Accurate control of the pulse angle is an important technical problem for reliably obtaining a compensation effect in the pulse echo method, and in the present embodiment, this problem is solved by providing the switch unit 161.

  In addition, the planar coil 114 for local measurement is miniaturized, and the reduction in noise during NMR reception is an important factor for ensuring the accuracy of measurement. When receiving an NMR signal, noise that enters the preamplifier 112 mainly includes an RF wave transmission system, which is caused by “RF wave leakage” or “high power amplifier” from the RF amplifier 106 that amplifies the excitation pulse. There is "noise". When receiving the NMR signal, it is necessary to reliably block the excitation wave leaking from the transmission side by the switch unit 161 and receive the NMR signal with low noise. In the present embodiment, this problem is also solved by the arrangement of the switch unit 161.

  The application of the excitation high-frequency pulse and the detection of the echo signal have been described above. However, these can be realized by an LC circuit (FIG. 8) including a small coil. In FIG. 8, the coil portion (inductance portion) of the resonance circuit is a small RF coil as described above. In the nuclear magnetic resonance (NMR) method, the atomic number density and the spin relaxation time constant can be measured by detecting the movement of nuclear magnetization as an NMR signal by the spin resonance phenomenon of a nucleus placed in a magnetic field. The spin resonance frequency in a magnetic field of 1 Tesla is about 43 MHz (this frequency band is called radio frequency). In order to selectively detect the frequency band with high sensitivity, an LC resonance circuit as shown in FIG. Used.

The excitation high frequency pulse applied to the film 115 by the planar coil 114 is, for example,
(A) a 90 ° pulse, and
(B) A pulse sequence including n 180 ° pulses applied at intervals of time 2τ, starting after the time τ of the pulses in (a) elapses. In order to clearly grasp the correlation between the T ₂ relaxation time constant and the amount of moisture in the film, it is important to appropriately apply the oscillating magnetic field. By setting it as the above patterns, the correlation between the T ₂ relaxation time constant and the amount of moisture in the film can be clearly grasped.

Here, if the 90 ° pulse is in the first phase and the n 180 ° pulses are in the second phase that is 90 ° shifted from the first phase, the T ₂ relaxation time constant and the moisture in the film A clear correlation with the quantity can be obtained stably.

When the planar coil 114 is used, it may be difficult to adjust the excitation pulse intensities (a) and (b). For example, in the region to be measured, that is, the region surrounded by the planar coil 114, a difference occurs in the excitation method between the central portion and the peripheral portion, so that the whole becomes a uniform excitation angle. That is, it may be difficult to excite so that the intensity ratio of the excitation magnetic field in (a) and (b) is constant. If the excitation angle ratio in (a) and (b) varies, accurate T ₂ measurement becomes difficult.

  Therefore, in such a case, in addition to the above pulse sequence, the pulse control unit 108 adds another sequence in which a step of applying a 180 ° pulse is added at a time τ before the 90 ° pulse (a). Make it run. Then, by comparing the behavior of the attenuation curve of the 180 ° pulse (b) corresponding to these two sequences, whether the excitation pulse intensity of the 90 ° pulse (a) and the 180 ° pulse (b) is accurate or not. Can be determined. As a result, even when the excitation pulse intensity is deviated due to an abnormality of the apparatus, the abnormality can be detected at a stage before the measurement is performed, and the measurement value can be made more accurate.

  The apparatus configuration around the film has been described above. Next, an echo signal processing block will be described.

The calculation unit 130 calculates a T ₂ relaxation time constant from the intensity of the echo signal, and calculates the water content at a specific location in the film from the calculated T ₂ relaxation time constant.

Inside the calculation unit 130, first, an echo signal is acquired by the data reception unit 120, and then a T ₂ relaxation time constant is calculated by the relaxation time constant calculation unit 122.

When the T ₂ relaxation time constant is calculated, the data is sent to the solvent amount calculation unit 124. The solvent amount calculation unit 124 accesses the calibration curve table (storage unit) 126 and acquires calibration curve data corresponding to the film. The calibration curve table 126 stores calibration curve data indicating the correlation between the amount of moisture in the membrane and the T ₂ relaxation time constant for each type of membrane.

The solvent amount calculation unit 124 calculates the amount of moisture in the film using the obtained calibration curve data and the T ₂ relaxation time constant calculated as described above. The calculated amount of water is presented to the user by the output unit 132. Various types of presentation types are possible, and there are no particular restrictions on display on the display, printer output, file output, and the like.

  In the present embodiment, a plurality of planar coils 114 may be arranged inside the film, on the film surface, or in the vicinity of the film. Thereby, it is comprised so that the application of the oscillating magnetic field for excitation and the acquisition of the echo signal corresponding to this can be performed with respect to several places of a film | membrane. The solvent amount distribution calculation unit 128 calculates the moisture amount distribution in the film based on the moisture amounts at a plurality of locations in the film. The output unit 132 outputs this moisture content distribution.

In the above apparatus, it is preferable to use a high frequency pulse for excitation by the CPMG method. By doing so, a clear correlation between the T ₂ relaxation time constant and the amount of water in the film can be stably obtained.

Therefore, a method for measuring the amount of protic solvent (for example, moisture) of the membrane 115 by the CPMG method in the measuring apparatus 100 will be described next.
In this measurement method, the film 115 is arranged in parallel to the flow path forming surface of the permanent magnet 113 in which the flow path groove is formed, and the amount of the protic solvent at a specific location in the film 115 is measured using the nuclear magnetic resonance method. A local measurement method includes the following steps.
First, a static magnetic field is applied in the thickness direction of the film 115 by the permanent magnet 113 while flowing the fluid containing the protic solvent in the flow channel groove of the permanent magnet 113 (S102). In this state, an excitation vibration magnetic field is sequentially applied to a part of the film 115 placed in a static magnetic field using an RF coil (planar coil 114) a plurality of times, and a plurality of vibration vibration magnetic fields corresponding to the excitation vibration magnetic field are applied. An echo signal is acquired (S104, first step above). Then, a T ₂ relaxation time constant is calculated from the intensity of these echo signals (S106). Then, data indicating the correlation between the amount of the protic solvent in the membrane 115 and the T ₂ relaxation time constant is acquired, and the data in the membrane 115 is identified from the data and the T ₂ relaxation time constant calculated in the second step. The amount of protic solvent at the location is determined (S108, second step above). Thereafter, the result is output (S110).

In step 104, an excitation high-frequency pulse is applied to the film. The excitation high-frequency pulse is preferably a pulse sequence composed of a plurality of pulses, and an echo signal group corresponding to the pulse sequence is acquired. By doing so, the T ₂ relaxation time constant can be accurately obtained. The pulse sequence is preferably composed of the following (a) and (b).
(A) a 90 ° pulse, and
(B) n 180 ° pulses applied at intervals of time 2τ, starting after the time τ of the pulse in (a) has elapsed.

In order to clearly grasp the correlation between the T ₂ relaxation time constant and the amount of moisture in the film, it is important to appropriately apply the oscillating magnetic field. By setting it as the above patterns, the correlation between the T ₂ relaxation time constant and the amount of moisture in the film can be clearly grasped. According to the method using the above pulse sequence, after τ time of the 90 ° excitation pulse, a 180 ° excitation pulse having twice the excitation pulse intensity is applied, and the phase of the magnetization vector M is changed to the xy plane (rotating coordinate system). ) reverses the disturbance of the phase turbulence will prematurely on, after 2τ time can be obtained echo signal to get on and converges the phase T ₂ decay curves on.

Here, if the 90 ° pulse is in the first phase and the n 180 ° pulses are in the second phase that is 90 ° shifted from the first phase, the T ₂ relaxation time constant and the moisture in the film A clear correlation with the quantity can be obtained stably. The CPMG method is an example of a method for providing such a pulse sequence.

In the CPMG method, first, the magnetization vector is tilted in the positive direction of the Y-axis by a 90 ° pulse, and after 180 hours, a 180 ° excitation pulse is irradiated from the outside in the “Y-axis direction”, so As a symmetry axis. As a result, after 2τ time, the magnetization vector converges on the “positive direction” of the Y axis, and an echo signal having a large amplitude is observed. Furthermore, after 180 hours, the magnetization vector is irradiated with a 180 ° excitation pulse from the outside in the “Y-axis direction” and converged again on the “positive direction” on the Y-axis, and an echo signal having a large amplitude after 4τ time. Observe. Further, irradiation with 180 ° pulses is continued at the same 2τ interval. During this time, the peak intensity of even-numbered echo signals of 2τ, 4τ, 6τ,... Is extracted and fitted with an exponential function, whereby the T ₂ (lateral) relaxation time constant by the CPMG method can be calculated.

In step 106, the T ₂ relaxation time constant is measured by utilizing the spin echo method.
Strength S _SE of the echo signal that may occur when using spin echo, in the case of TR >> TE is represented by the following formula (A).

  Where ρ is the density distribution of the target nuclide as a function of the position (x, y, z), TR is the 90 ° excitation pulse repetition time (about 100 ms to about 10 s), and TE is the echo time (about 2 t, about 1 ms to 100 ms) ), A is a constant that represents device characteristics such as RF coil detection sensitivity and amplifier.

An echo signal group riding on T ₂ decay curves, from the above equation (A), can be obtained the T ₂ relaxation time constant.
More specifically, the peak intensity of even-numbered echo signals of 2τ, 4τ, 6τ,... The peak intensity of the plurality of echo signals gradually decreases with time. By fitting the intensities of a plurality of echo signals that decay with time with an exponential function, the T ₂ relaxation time constant can be obtained from the above equation (A).

In step 108, the water content is calculated from the relaxation time constant. The amount of water in the film and the T ₂ relaxation time constant have a positive correlation. As the amount of water increases, the T ₂ relaxation time constant increases. Since this correlation varies depending on the type and form of the membrane, it is desirable to prepare a calibration curve for a membrane of the same type as the membrane to be measured whose moisture concentration is known in advance. That is, it is desirable to measure the relationship between the moisture content and the T ₂ relaxation time constant for a plurality of standard sample films with known moisture content, and to obtain a calibration curve representing this relationship in advance. By referring to the calibration curve thus created, the amount of water in the film can be calculated from the measured T ₂ relaxation time constant.

The T ₂ relaxation time constant of the entire film is expressed by the following formula when expressed by the simplest formula.
1 / T ₂ (total) = (adsorbed water amount) / (adsorbed water T ₂ ′) + (free water amount) / (free water T ₂ ″) (1)

The observer measures this T ₂ (total). When free water that fills the space increases, T ₂ (overall) increases, and therefore the amount of water in the polymer can be determined from the measurement result of T ₂ (overall).

Next, the effect of this embodiment is demonstrated.
In the present embodiment, the permanent magnet 113 and the planar coil 114 are of a specific shape, and these and the film 115 are arranged in a specific positional relationship. Thereby, first, a fluid containing a protic solvent is caused to flow in the concave portion 105 of the permanent magnet 113 to form a distribution in the amount of the protic solvent in the film 115, and the formed distribution can be measured by the planar coil 114. It is also possible to adjust the amount of protic solvent in the film 115 and measure the spatial distribution of the amount of protic solvent in the film 115 with the planar coil 114.

  Therefore, according to the measuring apparatus 100, for example, the moisture content distribution in the film 115 can be measured on the spot. Further, the dispersion behavior of water in the in-plane direction of the film 115 can be evaluated.

  Further, by taking the measurement region of the film 115 to be included in the first region 107 and the second region 109, the local moisture content measurement of the film 115 can be performed with higher accuracy and good reproducibility. In particular, as described above with reference to FIG. 3B, the second region 109 that is an upper region of the convex portion 103 is in a direction (z direction) perpendicular to the flow path forming surface of the permanent magnet 113. There is a position where the static magnetic field is maximized. If measurement is performed at such a position, fluctuations in the measurement value due to the displacement of the measurement region can be suppressed, and more accurate measurement can be performed.

  For example, in the present embodiment, a magnetic field is applied only to a position and place where measurement is desired on a thin sheet-like film 115 such as a polymer electrolyte, and a planar RF detection coil is used in the gap between the magnet and the film. To measure the local water content. Also, local measurement can be performed in a shorter time than MRI measurement.

  Moreover, in the measuring apparatus 100, since the NMR sensor can be made compact, restrictions on the installation location of the apparatus are relaxed. In addition, the price of the equipment can be reduced. In addition, if an integrated apparatus combining the planar coil 114 and the permanent magnet 113 is used, it is not necessary to align the two, and measurement can be performed easily.

In the present embodiment, the permanent magnet 113 can be downsized. Here, in FIG. 10 and FIG. 12, the configuration in which the uneven surface of the permanent magnet 113 is larger than that of the film 115 is illustrated, but the permanent magnet 113 only needs to be able to form a static magnetic field at the measurement location of the film 115. It is not limited to the case where the uneven surface is larger than the film 115. If a small magnet is used as a permanent magnet, a magnetic field is applied only to a part of the film, and an NMR signal can be received from only a region where the magnetic field is applied by a small RF detection coil, for example, the following advantages are produced. Is possible.
First, the dimensions of the membrane are arbitrary and are not limited to magnet dimensions.
Second, the magnet shape can be arbitrarily set. Therefore, for example, when applied to a fuel cell, a structure in which a gas flow path portion is incorporated in a magnet can be obtained.
Thirdly, by using a magnet and an RF detection coil suitable for a thin sheet polymer electrolyte membrane, the local water content of the membrane at the position to be measured can be measured.
Fourthly, local measurement is possible, and measurement can be performed in a shorter time than MRI measurement.
Fifth, restrictions on the device material that can be used are relaxed, and it is not necessary to use all non-magnetic material for the device, so there is a possibility that it can be installed in a fuel cell close to the actual device.
Sixth, the NMR sensor can be made more compact, easier to install, and less expensive.
With the development of an NMR measurement apparatus equipped with such a new permanent magnet 113, the applicable range of the NMR sensor can be expanded.

  Note that the configuration of the measuring apparatus in the present embodiment may be as shown in FIG. 12, for example. FIG. 12 is a diagram illustrating another configuration of the measuring apparatus including the permanent magnet 113 and the planar coil 114.

(Fourth embodiment)
In the present embodiment, a solid polymer electrolyte fuel cell including the measuring apparatus 100 (FIG. 10) described in the third embodiment will be described.

When the moisture content of the solid polymer electrolyte membrane of a fuel cell is measured by the NMR method, if a magnet that covers the entire membrane to be measured is used, all components of the fuel cell are made of non-magnetic materials. It is necessary to manufacture, and it is necessary to manufacture an apparatus for NMR / MRI measurement. However, its manufacture is difficult from the viewpoint of heat resistance and durability.
In addition, when a magnet that covers the entire membrane is used, a large magnet is also incorporated into the actual fuel cell and used as a monitoring device. However, the magnet is too large to be mounted, and it is not a practical sensor.

On the other hand, the measuring apparatus 100 described in the third embodiment has a structure in which the concave portion 105 of the permanent magnet 113 can be used as a gas flow path portion.
Therefore, in this embodiment, the permanent magnet 113 is incorporated in the fuel cell device as a part of the separator of the fuel cell, and the moisture content of the membrane 115, that is, the solid polymer electrolyte membrane 117 can be measured.
By incorporating the measuring apparatus 100 into the fuel cell, the water content of the polymer electrolyte membrane of the fuel cell can be constantly monitored and controlled so that the polymer electrolyte membrane can always maintain high conductivity. . For this reason, it becomes possible to control the operation of the fuel cell so as to keep the power generation efficiency of the fuel cell high.

FIG. 45 is a diagram showing the configuration of the fuel cell of the present embodiment.
45 includes a measuring apparatus 100, a cell 133, an oxidant gas supply unit 32 that supplies an oxidant gas (for example, oxygen or air) to the cell 133, and a fuel gas (for example, hydrogen gas) to the cell 133. The fuel gas supply unit 33 for supplying gas, the oxidant gas supplied from the oxidant gas supply unit 32 toward the cell 133, and the water vapor mixed with the fuel gas supplied from the fuel gas supply unit 33 toward the cell 133 It has a mixing unit 34, a water vapor mixing unit 35, and a control unit 36.

FIG. 46 is a cross-sectional view showing a configuration of cell 133 of fuel cell 131 shown in FIG.
The cell 133 includes a solid polymer electrolyte membrane 117 as a sample to be measured, a catalyst layer 311A and a catalyst layer 311B provided on both sides of the solid polymer electrolyte membrane 117, a porous diffusion layer 312A and a diffusion layer 312B, , Separator 313A and separator 313B.

  The catalyst layer 311A and the diffusion layer 312A constitute a fuel electrode 314, and the catalyst layer 311B and the diffusion layer 312B constitute an oxidant electrode 315.

  The separator 313A is formed with a groove serving as a fuel gas flow path. A fuel gas containing water vapor is supplied to the flow path groove of the separator 313A as a fluid containing a protic solvent. Further, the separator 313B is formed with a groove serving as a flow path for the oxidant gas. An oxidant gas containing water vapor is supplied to the flow path groove of the separator 313B as a fluid containing a protic solvent.

  In the fuel cell 131, at least one of the separators provided opposite to the fuel electrode or the oxidant electrode, that is, the separator 313A or the separator 313B, includes the permanent magnet 113 described in the first embodiment. The flow path forming surface of the permanent magnet 113 is disposed so as to face the fuel electrode of the fuel cell 131 and fuel gas is supplied to the recess 105, or is disposed to face the oxidant electrode of the fuel cell 131, so that the recess 105 Is supplied with an oxidant gas. The separator 313A or the separator 313B may be composed of the permanent magnet 113, or the permanent magnet 113 may constitute a part of the separator 313A or the separator 313B.

The oxidant gas supply unit 32 supplies oxidant gas to the cell 133. The fuel gas supply unit 33 supplies fuel gas to the cell 133.
A water vapor mixing unit 34 is provided between the oxidant gas supply unit 32 and the cell 133. The water vapor mixing unit 34 generates water vapor and mixes the water vapor with the oxidant gas supplied from the oxidant gas supply unit 32 toward the cell 133. The oxidant gas thus mixed with the water vapor is supplied to the cell 133.
Similarly, a steam mixing unit 35 is provided between the fuel gas supply unit 33 and the cell 133. In the water vapor mixing unit 35, water vapor is generated and mixed with the fuel gas supplied from the fuel gas supply unit 33 toward the cell 133. The fuel gas mixed with the water vapor is sent to the cell 133.
As described above, the solid polymer electrolyte membrane 117 of the cell 133 is wetted by mixing the water vapor with the oxidant gas and the fuel gas.

  When measuring the moisture content in the solid polymer electrolyte membrane 117 of the cell 133, the plurality of planar coils 114 of the measuring device 100 are brought into contact with the surface of the solid polymer electrolyte membrane 117. Thereby, the water content in the solid polymer electrolyte membrane 117 can be measured.

The control unit 36 is connected to the measuring device 100, the water vapor mixing unit 34, and the water vapor mixing unit 35.
The control unit 36 acquires the moisture content measurement result and the moisture content distribution from the measuring device 100, and is generated by the steam mixing unit 34 and the steam mixing unit 35 based on the measurement result and supplied to the cell 133. The water vapor mixing unit 34 and the water vapor mixing unit 35 are controlled so as to adjust the amount of water vapor.

For example, when the cell 133 is generating power, the water in the solid polymer electrolyte membrane 117 moves from the fuel electrode 314 side to the oxidant electrode 315 side as hydrogen ions generated on the fuel electrode 314 side move. To do.
Further, water is generated by the reaction between hydrogen ions and oxygen gas on the oxidant electrode 315 side. Therefore, the amount of water in the solid polymer electrolyte membrane 117 may be excessive particularly on the oxidant electrode 315 side. If the amount of water is excessive, water aggregates in the flow path of the separator 313B, which obstructs the flow of the oxidant gas, and power generation efficiency may be reduced.
On the other hand, when sufficient water vapor is not supplied to the solid polymer electrolyte membrane 117 and the solid polymer electrolyte membrane 117 is in a dry state, proton conductivity is lowered and the power generation efficiency of the cell 133 is lowered. Therefore, it is not preferable that the solid polymer electrolyte membrane 117 is in a dry state and proton conductivity is lowered.

  Therefore, the control unit 36 acquires the moisture content distribution from the measuring apparatus 100 and determines whether the moisture content value in the acquired distribution is within a predetermined range, that is, the solid polymer electrolyte membrane 117 is moderately wet. Determine if it is in a state. When it is determined that the predetermined range is exceeded, the control unit 36 requests the water vapor mixing unit 34 or the water vapor mixing unit 35 to reduce the amount of water vapor generated.

  On the other hand, when it is determined that the value of the moisture content in the moisture content distribution obtained from the measuring apparatus 100 is outside the predetermined range and the moisture content is small, the control unit 36 performs the steam mixing unit 34 or the steam mixing unit 35. On the other hand, the amount of water vapor to be generated is required to be increased, and the solid polymer electrolyte membrane 117 is prevented from being dried.

  In the present embodiment, the control unit 36 adjusts the water vapor generation amount of both the water vapor mixing unit 34 and the water vapor mixing unit 35 and the water vapor supply amount to the cell 133. However, the present invention is not limited to this. Only the water vapor generation amount of 35 and the water vapor supply amount to the cell 133 may be adjusted.

  By utilizing this, it is possible to perform NMR measurement of a plurality of polymer electrolyte membranes by installing a plurality of RF detection coils inside. For example, with the arrangement shown in FIG. 7 described later, the water content of a plurality of PEMs can be measured with one magnet.

Next, the effect of this embodiment is demonstrated.
In the fuel cell 131, since the permanent magnet 113 can be used as a separator, the local water content distribution of the solid polymer electrolyte membrane 117 is measured while fuel or an oxidant is allowed to flow in the flow channel of the permanent magnet 113. Can do. Since the moisture content distribution in the solid polymer electrolyte membrane 117 during operation can be measured on the spot, it is possible to control to improve the operation efficiency of the battery.
For example, if the amount of water in the solid polymer electrolyte membrane 117 at the top of the recess 105 is measured, the amount of water in the membrane near the region where fuel or oxidant is supplied into the membrane can be measured in real time.
Further, if the amount of water in the solid polymer electrolyte membrane 117 at the top of the convex portion 103 is measured, the diffusion state of the protic solvent supplied from the channel groove can also be grasped.

  In addition, for thin sheet-like samples such as polymer electrolyte membranes, it is necessary to be able to install an RF detection coil that applies a magnetic field only to the position and location where measurement is desired, without greatly changing the overall shape of the battery. . In this regard, in the fuel cell according to the present embodiment, by using the permanent magnet 113 as a separator, the solid polymer electrolyte membrane 117 is disposed in parallel to the separator surface and in the vicinity of the separator. For this reason, it has a configuration suitable for measurement of the solid polymer electrolyte membrane 117 disposed in a magnetic field formed in the vicinity of the flow path forming surface of the separator. Further, by using the planar coil 114 as the RF coil, it is easy to stack the coil at a predetermined position near the surface of the solid polymer electrolyte membrane 117, and the thickness of the cell 133 is greatly increased. It is possible to incorporate a moisture measuring device without change. As described above, in the fuel cell 131, the configuration of the permanent magnet 113 and the planar coil 114 is adapted to the thin sheet-like solid polymer electrolyte membrane 117, and the local area of the membrane at the position where measurement is desired. The water content can be measured.

  Further, in this embodiment, since the magnetic field is applied only to a part of the apparatus, restrictions on usable apparatus materials are alleviated, and it is not necessary to use all of the apparatus as a non-magnetic material. It has become.

  Further, in the fuel cell 131, the planar coil 114 is brought into contact with the surface on the fuel electrode 314 side and the surface on the oxidant electrode 315 side of the solid polymer electrolyte membrane 117, and the vicinity of the surface on the fuel electrode 314 side is oxidized. It is also possible to grasp the amount of water near the surface on the agent electrode 315 side and grasp the relationship between the amount of water near the surface of each electrode and the power generation efficiency. Thereby, it is also possible to grasp whether the supply of water vapor from either the fuel electrode 314 side or the oxidant electrode 315 side is effective for power generation efficiency.

  Furthermore, the fuel cell 131 of the present embodiment provides useful data for searching for the cause of the decrease in power generation efficiency that occurs when the cell 133 is operated for a long time from the viewpoint of “water content of polymer membrane”. Can do.

Note that the fuel cell of the present embodiment may be of a stack type in which a plurality of cells are stacked as shown in FIG. Also in the case of a stack type fuel cell, the permanent magnet 113 can be a “permanent magnet with gas flow path”, that is, a separator.
FIG. 7 is a cross-sectional view showing a configuration of a stack type fuel cell including a plurality of cells including a solid polymer electrolyte membrane 117a and a solid polymer electrolyte membrane 117b.
In FIG. 7, the permanent magnet 113 is provided as the outermost separator. The permanent magnet 113 is provided to face the endmost cell (solid polymer electrolyte membrane 117b) of the fuel cell stack, holds the solid polymer electrolyte membrane 117b with the convex portion 103 of the permanent magnet 113, and has a concave portion. A fuel gas or an oxidant gas flows through 105. In FIG. 7, the separator 111 is a normal separator that does not have the permanent magnet 113.

  Further, from FIG. 3B described above, the magnetic field strength is about 0.2 to 0.3 Tesla even at a position away from the magnet (z> 10 mm). With such a magnetic field strength, NMR measurement is sufficiently possible. Therefore, even if a magnet is placed at the extreme end of the fuel cell stack, a magnetic field is formed even inside the stack. Moreover, since the static magnetic field strength gradually decreases as the distance increases, the resonance frequency also decreases as the distance from the magnet increases. If the resonance frequency is different, interference of excitation pulses in a plurality of RF coils is less likely to occur.

  Moreover, there is no restriction | limiting in particular in the use of the fuel cell of this invention. For example, it may be used not only as a battery but also as an evaluation apparatus for the solid polymer electrolyte membrane 117.

  As mentioned above, although embodiment of this invention was described with reference to drawings, these are the illustrations of this invention, Various structures other than the above are also employable.

  For example, in the above embodiment, the measuring apparatus 100 includes a plurality of planar coils 114, and the plurality of planar coils 114 applies an excitation oscillating magnetic field to a plurality of locations of the film 115 and the excitation oscillating magnetic field. And the solvent amount calculation unit 124 may be configured to calculate the amount of protic solvent at a plurality of locations of the membrane 115. By disposing the planar coil 114 at a plurality of locations on the membrane 115 and measuring the amount of protic solvent, the distribution of the amount of protic solvent in the membrane 115 can be measured in a shorter time. At this time, if a plurality of planar coils 114 are arranged on one first region 107 or one second region 109 described above with reference to FIG. 6, the deviation of the static magnetic field strength in the film thickness direction is suppressed. Thus, multipoint measurement with even higher accuracy becomes possible.

In the above embodiment, the case where the relaxation time constant T ₂ is calculated from the echo signal acquired by the CPMG method and the amount of the protic solvent in the membrane is calculated from the calculated T ₂ has been described as an example. As will be described later in the embodiment, the amount of the protic solvent can be obtained from the signal intensity of the echo signal.
Since T ₂ does not depend on the device configuration such as RF coil sensitivity, amplifier magnification, filter characteristics, etc., calculating the amount of protic solvent in the membrane from T ₂ makes the amount of protic solvent even easier. Can be calculated. Further, when calculating the amount of protic solvent from the signal intensity, a calibration curve for associating the signal intensity with the amount of protic solvent may be obtained in advance by experiments in accordance with the configuration of the measuring apparatus.

Further, in the above embodiment, for example, the following can be performed.
That is, a double-D type suitable for a thin sheet-like polymer electrolyte membrane using a gas flow path magnet attached to a magnet and using a gas flow path magnet that can be incorporated into a fuel cell device as a part of a fuel cell separator The local moisture content of the membrane at the position (depth) to be measured can be measured by the RF detection coil.
Further, if the gas flow path magnet and the Double-D type coil are installed and measured at the position or place where the fuel cell is to be measured, it is only necessary to apply the magnetic field only to that place. This eliminates the need for the device at a position other than the magnetic field application location to be made of a non-magnetic material, so that the NMR sensor can be applied to a more practical fuel cell device.
In addition, the NMR sensor can be made compact, easy to install, and low in equipment cost.
In addition, if an integrated apparatus combining an RF detection coil and a magnet is used, positioning of the two is unnecessary and measurement can be performed easily.
Also, if this sensor is incorporated into a fuel cell, the water content of the polymer electrolyte membrane of the fuel cell can be constantly monitored and controlled so that it can always maintain high conductivity. It is possible to maintain high power generation efficiency.

Moreover, although the case where the amount of the protic solvent of the solid polymer electrolyte membrane of the fuel cell is mainly exemplified in the above embodiment, the sample to be measured may be in the form of a membrane.
Further, the sample is not limited to a solid sample as long as it is in the form of a film, and may be, for example, a liquid containing a protic solvent filled in a space having a predetermined thickness. Further, the sample is not limited to a film made of a solid polymer electrolyte or the like, and for example, a predetermined layer such as a catalyst layer may be formed on one or both surfaces of the film.

Example 1
In this example, T ₂ (CPMG) values of the samples A to C shown below were measured by the CPMG method using the measurement apparatus (third embodiment) shown in FIG.
(Sample A) Liquid sample (water)
(Sample B) Polymer electrolyte membrane (PEM)
(Sample C) Polymer electrolyte membrane with electrode and catalyst (MEA)
Was used. In this example, the permanent magnet shown in FIG. 2 was used. The material of the permanent magnet was NEOMAX-44H manufactured by NEOMAX.

(Sample A) Liquid sample (water)
FIG. 13 is a diagram showing a sample of this example. The sample was prepared according to the following procedure. First, two cover glasses (dimensions 18 mm × 18 mm, thickness 0.12 mm) were bonded with a gap of 0.5 mm to produce a container. Water was poured into the container and the container was sealed. The dimensions of the water part are 15 mm × 15 mm × thickness 0.5 mm. Hereinafter, this sample is also referred to as a “0.5 mm thick water sample”.

  A 0.5 mm thick water sample was regarded as a PEM and placed at the position of a solid polymer electrolyte membrane (PEM) 117 having the arrangement shown in FIG. FIG. 14A is a diagram showing a state in which a Double-D coil is placed on a permanent magnet with a gas flow path, and a “0.5 mm thick water sample” is placed thereon.

  Moreover, the apparatus used for NMR measurement was shown in FIG.14 (b). A magnet, a coil, and a sample (FIG. 14A) were placed in a brass electromagnetic shielding box at the lower left in FIG. 14B and measured. Noise from the outside is blocked by this shield. CPMG measurement was performed using this apparatus.

  An echo signal obtained by CPMG measurement with a 0.5 mm thick water sample is shown in FIG. The NMR measurement parameters were as follows. The 90-degree excitation pulse repetition time (TR) is 5 seconds, the 90-degree excitation pulse dummy count is 4, the NMR signal integration count is 64, and the resonance frequency is 13.07 MHz. The temperature of the 0.5 mm thick water sample was about 25 ° C.

FIG. 16 shows a state where only the “even-numbered echo signal intensity” is extracted from the acquired echo signals and is logarithmically plotted. Based on this data, linear approximation was performed by the least square method, and T ₂ (CPMG) was calculated from the gradient of the straight line. As a result, T ₂ (CPMG) was 24 ms.

CPMG measurement was performed by changing the distance between the Double-D type RF detection coil and the 0.5 mm thick water sample in 0.5 mm increments, and the relationship with the echo signal intensity was obtained. The result is shown in FIG.
FIG. 17 shows that the echo signal intensity becomes maximum when the distance (gap) between the coil and the sample is 1 mm. Since the sample thickness is 0.5 mm, a distance of 1 mm means that there is a water sample between 1.0 mm and 1.5 mm from the coil. This distance corresponds to the distance (1.2 mm) between the two semicircular coils of the Double-D coil. From this result, in the Double-D type coil, it is possible to measure the position (depth) separated by about the gap of the half-moon shaped coil, and to measure the inside of the sample a little.

  From this example, it can be seen that in the Double-D type coil, the measurement depth changes in accordance with the geometric dimension of the coil. Therefore, it is possible to measure the thickness direction (depth direction) distribution in the polymer film by using a coil according to a desired measurement depth.

(Sample B) Polymer electrolyte membrane (PEM)
As a polymer electrolyte membrane (PEM), Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd. was used. The dimensions of the PEM are 15 mm × 15 mm × thickness 0.5 mm. The membrane was previously standardized by immersing in an order of 3% hydrogen peroxide solution at 80 ° C., ion exchange water, 1N hydrochloric acid, and ion exchange water for 1 hour each.

  Immediately before the experiment, the PEM soaked in ion-exchanged water was taken out, wiped with dry Kimwipe (registered trademark), and dried appropriately to adjust the water content of the PEM. After the adjustment, the PEM was quickly sandwiched between two cover glasses (dimensions 18 mm × 18 mm, thickness 0.12 mm) and sealed with a polyimide film so as not to be dried. This is shown in FIG. The mass of PEM was measured with an electronic balance, and it was confirmed that the water content did not change before and after NMR measurement.

The water content of the PEM was calculated from the increase in mass by measuring the mass of the sufficiently dried PEM with an electronic balance and measuring the mass of the PEM in the water-containing state.
In this example, the water content of PEM was changed to 14.9 [H ₂ O / SO ₃ ⁻ H ⁺ ] and 12.4 [H ₂ O / SO ₃ ⁻ H ⁺ ]. The PEM sample itself is the same sample, and only the water content is different.

  Similar to the measurement with the “0.5 mm thick water sample” of sample A, the PEM was placed at the position shown in FIG. A Double-D type coil was placed on a permanent magnet with a gas flow path, a “polymer electrolyte membrane (PEM)” was placed thereon, and this was placed in a brass shield box to perform CPMG measurement.

FIG. 19 shows an echo signal obtained by CPMG measurement using a PEM having a water content of 14.9 [H ₂ O / SO ₃ ⁻ H ⁺ ] as a sample. The NMR measurement parameters were as follows. The 90-degree excitation pulse repetition time (TR) is 5 seconds, the 90-degree excitation pulse dummy count is 0, the NMR signal integration count is 64, and the resonance frequency is 13.07 MHz. The temperature of the polymer electrolyte membrane (PEM) was about 25 ° C.

FIG. 20 shows a state where only the “even-numbered echo signal intensity” is extracted from the echo signal acquired by the PEM and logarithmically plotted in the same manner as the 0.5 mm thick water sample. Based on this data, linear approximation was performed by the least square method, and T ₂ (CPMG) was calculated from the gradient of the straight line. As a result, T ₂ (CPMG) was 34 ms.

Moreover, the same measurement was performed with PEM having a water content of 12.4 [H ₂ O / SO ₃ ⁻ H ⁺ ]. The CPMG measurement was performed 3 times with each water content PEM, and the calculated T ₂ (CPMG) value is shown in FIG. The straight line is connected based on the average value of three T ₂ (CPMG) values.

FIG. 21 shows that the T ₂ (CPMG) value decreases as the water content decreases.
Moreover, when the water content of PEM decreased, the echo signal intensity also decreased. FIG. 22 shows the relationship between the echo signal intensity and the water content acquired from the two water content PEMs. The echo signal intensity used here is an average value of the third, fourth, and sixth echo signal intensities obtained by CPMG measurement. Such an averaging operation was performed in order to suppress variations in signal intensity.

  From FIG. 21 and FIG. 22, it was found that a quantitative relationship between the water content of PEM and the echo signal intensity can be obtained. Therefore, the water content of the PEM can be converted based on the intensity of the echo signal.

(Sample C) Polymer electrolyte membrane with electrode and catalyst (MEA)
Furthermore, an experiment for obtaining a T ₂ (CPMG) value was performed using an electrode / catalyst-attached polymer electrolyte membrane (MEA) provided with an electrode and catalyst on the surface of the polymer electrolyte membrane (PEM).
MEA was performed with reference to Non-Patent Document 2. Specifically, a polymer electrolyte membrane manufactured by Asahi Glass Co., Ltd. was electrolessly plated with Pt and Ir on the anode side and Pt on the cathode side. The dimensions of the MEA are 17 mm × 15 mm square and 500 μm thickness.

The standardized MEA was pulled up from ion-exchanged water just before the experiment and pressed against Kimwipe to sufficiently wipe off the water. The water content of the experimental immediately preceding MEA about _{15 [H 2 O / SO 3} - H +] is. After wiping off the water, the MEA was quickly sandwiched between two cover glasses (dimensions 18 mm × 18 mm, thickness 0.12 mm) and sealed with a polyimide film to prevent drying. This is shown in FIG.

  Similar to the measurement with the “0.5 mm thick water sample” of sample A, the MEA was placed at the position shown in FIG. A Double-D type coil was disposed on a permanent magnet with a gas flow path, and a “polymer electrolyte membrane with electrode / catalyst (MEA)” was disposed thereon. This was put into a brass shield box and CPMG measurement was performed.

FIG. 24 shows an echo signal obtained by CPMG measurement using MEA as a sample. The NMR measurement parameters were as follows. The 90-degree excitation pulse repetition time (TR) is 5 seconds, the 90-degree excitation pulse dummy count is 0, the NMR signal integration count is 64, and the resonance frequency is 13.07 MHz. The temperature of the electrode / catalyst-attached polymer electrolyte membrane (MEA) was about 25 ° C.
FIG. 25 shows a state in which only the “even-numbered echo signal intensity” is extracted from the echo signal acquired by the MEA and logarithmically plotted in the same manner as the sample A 0.5 mm thick water sample. Based on this data, linear approximation was performed by the least square method, and T ₂ (CPMG) was calculated from the gradient of the straight line. As a result, T ₂ (CPMG) was 41 ms.

From the above, even when the sample was a polymer electrolyte membrane with electrode / catalyst (MEA), an appropriate T ₂ (CPMG) value could be measured.
Therefore, CPMG measurement of the electrode / catalyst polymer electrolyte membrane (MEA) can be performed using the permanent magnet with gas flow path and the Double-D type RF coil manufactured so as to be mounted in the fuel cell, and the calculated T _{2 It} can be seen that the water content in the polymer electrolyte membrane can be estimated from the (CPMG) value.

As described above, it was confirmed that for any of Sample A to Sample C, a significant T ₂ (CPMG) value can be calculated by CPMG measurement.

Non-Patent Document 1 describes that the water content value of the solid polymer electrolyte membrane of the fuel cell is about 4 to 6 [H ₂ O / SO ₃ ⁻ H ⁺ ]. _{2 [H 2 O / sO 3} - H +] if it is possible to detect the variation in the degree of water content, considered can be suitably used for the evaluation of the solid polymer electrolyte membrane of the fuel cell. In this respect, it can be seen from the above measurement results that the method of this example has a detection sensitivity that can sufficiently detect fluctuations in the water content of the solid polymer membrane.

Further, the concentration per unit volume of the protic solvent in the fuel gas and the oxidant gas flowing in the separator channel during the operation of the fuel cell is very small compared to the concentration of the protic solvent in the polymer electrolyte membrane. As a result, the echo signal from the gas is negligibly small. For this reason, even if a gas containing a protic solvent is caused to flow in the flow channel groove of the permanent magnet, T ₂ (CPMG) measurement can be performed with the same measurement accuracy as in the state where no flow is made.

(Example 2)
In this embodiment, the excitation magnetic field distribution H _x created by the Double-D type coil is theoretically analyzed, and the echo signal intensity distribution S _{SE_Detect} (equivalent to the measurement region) received by the coil when the CPMG method is used is quantitatively calculated. did. In particular, it was confirmed that the NMR signal acquisition region was separated from the coil when the distance L between the two D-type coils was changed. It was also shown that the measurement depth can be changed by adjusting the interval L.

  The geometric shape of the Double-D coil was almost the same as the shape used in Example 1, the diameter D = 12 mm, three turns, and the distance between the two D-type coils was L = 1.2 mm. FIG. 26A and FIG. 26B are diagrams showing the configuration of the Double-D type coil analyzed in this example. FIG. 26 (a) shows the shape of the Double-D coil in the case of one turn, but in actual calculation, as shown in FIG. 26 (b), three turns were used.

  As the shape parameter, the distance L between the two D-shaped coils was changed to 0.6 mm, 1.2 mm, 1.8 mm, and 2.4 mm, and the change in the NMR signal acquisition region (measurement region) received by the coil was examined. .

(Analysis of formation region of oscillating magnetic field for excitation)
First, the excitation magnetic field H _x (x _p , y _p , z _p ) formed by the three-turn Double-D coil having the geometric shape shown in FIG. 27 was analyzed under the following assumptions.
(I) The coil wire diameter is zero (infinitely small wire diameter).
(Ii) There is no skin effect during conduction. Since the wire diameter is zero, the effect of current flowing only on the coil surface is ignored.
(Iii) In the three-turn coil, three circles having different diameters are arranged concentrically as shown in FIG. 26 (b), and the interval between the first and second straight wire portions is set to L1 and the second turn straight line in order from the largest arc. The interval between the partial conductors was L2, and the interval between the third winding straight portion conductors was L3 (L1>L2> L3).
(Iv) The coil is made only of a conductive wire, and the coating film is ignored. The dielectric constant and permeability use vacuum values.
(V) There is no sample (membrane). Vacuum values are used for permittivity and permeability throughout the space.
(Vi) Lead parts (wiring parts other than circular coils) are ignored.

  Under the above assumption, the magnetic field H generated by the current I flowing through the conductor was calculated based on Bio-Savart's law. For explanation, the circular coil shown in FIGS. 28A and 28B will be described as an example. In FIG. 28, for convenience of explanation, the planar shape of the coil is circular, but in the analysis, it is the shape shown in FIG.

When the circular coil is placed in a vacuum (permeability is 4π × 10 ⁻⁷ N / A ² ), the magnetic field H (x _p , y _p ) created by the circular coil at the position (x _p , y _p , z _p ) , Z _p ) is expressed by equation (2).

The coordinate system of the above formula (2) is as shown in FIG. 28, and the meanings of symbols in the formula (2) are as follows.
H: Magnetic field strength at position r [A / m] (vector)
r: position (x _p , y _p , z _p ) [m] (vector) of point P in space
r ′: position of the point Q on the coil (x _q , y _q , z _q ) [m] (vector)
I: Current [A] (scalar)
t: unit vector representing the direction of current flow (represents the shape of the coil at point Q. In FIG. 28, when the angle between point Q and the x-axis is θ, t is t = (sin θ, cos θ, 0). [-] (Vector)
Meaning of integration: Line integration is performed over the entire circumference of the coil. The magnetic field generated at the point P is obtained by moving the point Q on the coil along the coil and integrating the magnetic field created at the position of each point Q over the entire circumference of the coil (obtaining the sum).

In the case of a Double-D type coil, a circular arc part and a straight line part are combined. Therefore, the coil shape was approximated as follows to make it almost equal to the shape of the Double-D type coil.
That is, the arc portion of the Double-D type coil is divided into a number of sections and approximated to be represented by a straight line having a length cL_ds [m] within the section. It is assumed that t in the section changes smoothly as the angle θ increases. Moreover, the linear part of the coil was divided as a linear element. This makes it possible to numerically calculate equation (2). In the present embodiment, one single-side D-shaped coil was divided into 16 straight lines, and the curved portion was also divided into 16 straight lines. This division method was the same for the first roll, the second roll, and the third roll (innermost). FIG. 29 shows parameters at the time of division. The center of the divided element is indicated by a point, and the entire shape is shown in FIG.

The current I flowing through the coil was set to 1A and L = 1.2 mm, and the x-direction magnetic field strength H _x (x _p , y _p , z _p ) in the space shown in FIG. 30 was numerically analyzed by the equation (2). It is an xz plane with y _p = 0 mm. However, since this calculation is a singular point on the coil and cannot be calculated, an area within a radius of 0.05 mm in the vicinity of the coil is excluded from calculation. FIG. 31 is a diagram showing overall contour lines of a 3-turn Double-D type coil. FIG. 32 is a diagram illustrating the z-position distribution H _x (z _p ) of the x-direction magnetic field strength. FIGS. 34 and 35 are enlarged views showing only the linear conductor portion (FIG. 33) of FIGS. 31 and 32, respectively. In FIGS. 31 and 34, the cross section of the coil is indicated by a white circle (◯).

  34 and 35, it can be seen that a magnetic field that can be considered uniform is formed around the apex where the magnetic field strength is highest. By arranging the coil so that this region is a measurement region of the Double-D type coil, variations in the excitation oscillating magnetic field can be suppressed, and more accurate measurement can be performed. It can be seen that the measurement region may be a region approximately 0.6 to 0.7 mm away from the coil.

  Similar magnetic field analysis was performed by changing the distance L between the two D-type coils to 0.6 mm, 1.2 mm, 1.8 mm, and 2.4 mm. FIG. 36A is a diagram showing a coil shape when the distance L is 0.6 mm, and FIG. 36B is a diagram showing a coil shape when L = 2.4 mm.

As an example of a magnetic field analysis, x-direction magnetic field strength of the three turns the Double-D coil when the distance L of two D-type coil 2.4mm distribution _{H x (x p, y p} , z p) Figure 37 Shown in FIG. 38 is a diagram showing the z-position distribution H _x (z _p ) of the x-direction magnetic field strength when L is 2.4 mm.

  Comparing FIG. 37 and FIG. 38 with the analysis result in the case of L = 1.2 mm, by setting L = 2.4 mm, the measurement area where the magnetic field intensity becomes maximum and the intensity becomes uniform is separated from the coil. I understand.

FIG. 39 is a diagram showing the z-position distribution H _x (z _p ) of the x-direction magnetic field strength when the distance L between the two D-type coils of the Double-D type coil is changed. From FIG. 39, it can be seen that the measurement region is further away from the coil as the distance L between the two D-type coils is increased.

  From the above analysis results, it became clear that in the Double-D type coil, the depth of the measurement region can be changed by adjusting the distance L between the two D type coils.

(Analysis of formation area of echo signal intensity distribution)
Next, using the analysis results of the magnetic field distribution above, both the “signal reception sensitivity of the Double-D coil” and the “relationship between the excitation angle α of nuclear magnetization and the signal intensity” based on an experimental relational expression In combination, the measurement area of the surface coil was calculated by the following procedure.
(I) Excitation angle distribution α (x _p , y _p when the excitation angle α at the position where H _x (0, 0, z _p ) is maximum on the central axis of the Double-D coil is 90 degrees. , Z _p ) were theoretically analyzed.
(Ii) Echo signal intensity distribution S _SE (x _p , y _p , z _p ) using an experimental relational expression that the echo signal intensity S _SE in the spin echo method is an excitation angle α and S _SE = (sin α) ^3. ) Was calculated. At this time, it was judged from the experimental results that the CPMG method and the echo method are the same.
(Iii) The signal reception sensitivity of the Double-D type coil is proportional to the magnetic field H _x (x _p , y _p , z _p ), and the echo signal reception intensity distribution S _{SE, Detect} ( x _p, y _p, was calculated z _p).

FIG. 40 shows the echo signal reception intensity distribution S _{SE, Detect} obtained by analyzing the case where the diameter D of the Double-D coil is 12 mm, the number of turns is 3 and the distance between the two D coils is L = 1.2 mm. _{(x p, y p, z} p) is a diagram showing a. In FIG. 40, the xz plane of only the central region of the Double-D type coil is shown enlarged. In the figure, a cross section of three straight line conductors of a Double-D type coil is schematically shown. The schematic meaning is that the diameter of the conducting wire is analyzed as zero.

  In FIG. 40, a region where the signal intensity is approximately 0.8 or more is indicated by being surrounded by a thick line. In the region surrounded by the bold line, echo signals are mainly acquired by the Double-D type coil, and this region can be regarded as a measurement region in the Double-D type coil in this case.

41 is a diagram showing the echo signal reception intensity distribution S _{SE, Detect} (0, 0, z _p ) on the z axis in FIG. In the case of this distribution, if a region where the signal intensity is approximately 0.8 or more is regarded as a measurement region in the Double-D type coil, it is the same as the region surrounded by the thick line in FIG.

FIG. 42 shows the echo signal reception intensity distribution S _SE obtained by analyzing the case where the diameter D of the Double-D coil is 12 mm, the number of turns is 3 and the distance between the two D coils is L = 2.4 mm. _{, Detect} (x _p , y _p , z _p ). 42, as in FIG. 40, the xz plane of only the central region of the Double-D coil is shown enlarged.

  Also in FIG. 42, a region where the signal intensity is approximately 0.8 or more is shown surrounded by a thick line. In FIG. 42, as compared with FIG. 40, it can be seen that the region where the signal intensity is approximately 0.8 or more is widened and at the same time, the region is separated from the coil.

FIG. 43 is a diagram showing the echo signal reception intensity distribution S _{SE, Detect} (0, 0, z _p ) on the z axis of FIG. FIG. 43 also shows a range that can be regarded as a measurement region of the Double-D type coil. Also in FIG. 43, it can be seen that the measurement area expands and at the same time moves away from the coil as compared with FIG.

FIG. 44 shows the echo signal reception intensity distribution S _{SE, Detect} (0,0) on the z-axis when the distance L between the two D-type coils is changed to 0.6 mm, 1.2 mm, 1.8 mm, and 2.4 mm. , Z _p ).
44, as the interval L between the D-type coils is increased _{, the} region where the normalized echo signal reception intensity distribution S _{SE, Detect} on the vertical axis is 0.8 or more increases, and further to a position where it is further away. You can see it moving. From this, it can be said that the measurement region can be changed from a position close to the coil to a position far away by adjusting the distance L between the two D-type coils.

  From the above results, when installing Double-D type coils in a fuel cell, for example, by installing multiple coils with different intervals L and switching individual coils from the transceiver, various thicknesses can be obtained. Water content measurement at the position can be realized.

  In this example, the analysis was performed with respect to the three-turn coil. However, regarding the five-turn coil used in Example 1, the width of the coil bundle was used in this example when viewed as a “coil bundle”. It has almost the same shape as the coil. If the widths are about the same, it may be considered that a magnetic field similar to the five-turn coil used in Example 1 is formed.

It is a figure which shows the structure of the permanent magnet in embodiment. It is a figure which shows the structure of the permanent magnet in embodiment. It is a figure explaining the measurement result of z position distribution of the static magnetic field strength formed with the permanent magnet in an embodiment. It is a figure explaining the measurement result of y position distribution of the static magnetic field strength formed with the permanent magnet in an embodiment. It is a figure explaining the measurement result of x position distribution of the static magnetic field strength formed with the permanent magnet in an embodiment. It is a perspective view explaining the static magnetic field formed by the permanent magnet in an embodiment. It is sectional drawing which shows the structure of the fuel cell in embodiment. It is a figure which shows the structure of the planar coil in embodiment. It is a figure which shows the structure of the planar coil in embodiment. It is a figure which shows the structure of the measuring apparatus in embodiment. It is sectional drawing which shows arrangement | positioning of the permanent magnet of the measuring apparatus of embodiment, a planar coil, and a sample. It is a figure which shows the structure of the measuring apparatus in embodiment. It is a figure which shows the sample used in the Example. It is a figure which shows the measuring apparatus in an Example. It is a figure which shows the measurement result of the echo signal in an Example. It is a figure which shows the measurement result of the echo signal in an Example. It is a figure which shows the relationship between the distance of the coil and sample in an Example, and echo signal intensity | strength. It is a figure which shows the sample used in the Example. It is a figure which shows the measurement result of the echo signal in an Example. It is a figure which shows the measurement result of the echo signal in an Example. Is a diagram showing the relationship between water content and T ₂ of the samples in Examples. It is a figure which shows the relationship between the moisture content of the sample in an Example, and echo signal intensity | strength. It is a figure which shows the sample used in the Example. It is a figure which shows the measurement result of the echo signal in an Example. It is a figure which shows the measurement result of the echo signal in an Example. It is a figure which shows the structure of the Double-D type coil in an Example. It is a figure which shows the structure of the Double-D type coil in an Example. It is a figure explaining the analysis method of the magnetic field in an Example. It is a figure which shows the analysis conditions of the magnetic field in an Example. It is a figure which shows z position distribution of the x direction magnetic field strength of the Double-D type coil in an Example. It is a figure which shows the contour line of the magnetic field formed with the Double-D type coil in an Example. It is a figure which shows z position distribution of the x direction magnetic field strength of the Double-D type coil in an Example. It is a figure which shows the analysis conditions of the magnetic field in an Example. It is a figure which shows the contour line of the magnetic field formed with the Double-D type coil in an Example. It is a figure which shows z position distribution of the x direction magnetic field strength of the Double-D type coil in an Example. It is a figure which shows the structure of the Double-D type coil in an Example. It is a figure which shows x direction magnetic field strength distribution Hx of the Double-D type coil in an Example. It is a figure which shows z position distribution of the x direction magnetic field strength of the Double-D type coil in an Example. It is a figure which shows z position distribution of the x direction magnetic field strength of the Double-D type coil in an Example. It is a figure which shows the echo signal receiving intensity distribution of the Double-D type coil in an Example. It is a figure which shows z position distribution of the echo signal receiving intensity of the Double-D type coil in an Example. It is a figure which shows the echo signal receiving intensity distribution of the Double-D type coil in an Example. It is a figure which shows z position distribution of the echo signal receiving intensity of the Double-D type coil in an Example. It is a figure which shows z position distribution of the echo signal receiving intensity of the Double-D type coil in an Example. It is a figure which shows the structure of the fuel cell in embodiment. It is a figure which shows the structure of the cell of the fuel cell in embodiment.

Explanation of symbols

32 Oxidant Gas Supply Unit 33 Fuel Gas Supply Unit 34 Water Vapor Mixing Unit 35 Water Vapor Mixing Unit 36 Control Unit 100 Measuring Device 101 Channel Groove 102 RF Oscillator 103 Convex Part 104 Modulator 105 Concave Part 106 RF Amplifying Part 107 First Area 108 Pulse Control unit 109 Second region 110 Phase detector 111 Separator 112 Preamplifier 113 Permanent magnet 114 Planar coil 115 Membrane 117 Solid polymer electrolyte membrane 117a Solid polymer electrolyte membrane 117b Solid polymer electrolyte membrane 118 A / D converter 119 First Coil unit 120 Data reception unit 121 Second coil unit 122 Relaxation time constant calculation unit 123 First linear region 124 Solvent amount calculation unit 125 Second linear region 126 Calibration curve table 127 First spacer 128 Solvent amount distribution calculation unit 129 Second Spacer 130 Arithmetic unit 131 Fuel cell 132 Output unit 133 Cell 135 Third spacer 137 Air gap 161 Switch unit 311A Catalyst layer 311B Catalyst layer 312A Diffusion layer 312B Diffusion layer 313A Separator 313B Separator 314 Fuel electrode 315 Oxidant electrode

Claims (15)

An apparatus for locally measuring the amount of a protic solvent at a specific location in a film using a nuclear magnetic resonance method,
A permanent magnet for applying a static magnetic field to the film;
An RF coil that applies an excitation oscillating magnetic field to a part of the film and acquires an echo signal corresponding to the excitation oscillating magnetic field;
From the intensity of the echo signal, a solvent amount calculation unit for calculating the amount of the protic solvent at a specific location of the membrane;
With
The permanent magnet is provided with a channel groove through which a fluid containing the protic solvent flows,
The measurement apparatus, wherein the film is provided in parallel to a flow path forming surface of the permanent magnet. The measuring apparatus according to claim 1,
The solvent amount calculation unit calculates a T ₂ relaxation time constant from the intensity of the echo signal, and calculates the amount of the protic solvent at a specific location of the membrane from the calculated T ₂ relaxation time constant. apparatus. The measuring apparatus according to claim 1 or 2,
The measuring device in which the flow channel groove of the permanent magnet is composed of a plurality of groove portions, and the groove portions are arranged in parallel to each other. The measuring device according to claim 3,
The measurement apparatus, wherein the RF coil forms the excitation oscillating magnetic field having an amplitude in a direction in the flow path forming plane and perpendicular to the extending direction of the groove. The measuring apparatus according to claim 4, wherein
The RF coil includes a pair of coil parts, and forms the excitation oscillating magnetic field in a region sandwiched between the pair of coil parts,
When viewed from above the flow path forming surface of the permanent magnet, the region sandwiched between the pair of coil portions is within a single groove portion forming region or a region sandwiched between adjacent groove portions. Measurement equipment included. In the measuring apparatus in any one of Claims 3 thru | or 5,
The RF coil is a planar coil in which a first coil part including a first linear region and a second coil part including a second linear region are connected,
The first coil portion and the second coil portion have a conductive wire reversely wound,
The first straight region and the second straight region are arranged in parallel to the extending direction of the groove,
When viewed from above the flow path forming surface of the permanent magnet, a region sandwiched between the first linear region and the second linear region is included in a region sandwiched between the adjacent groove portions. ,measuring device. In the measuring apparatus in any one of Claims 3 thru | or 5,
The RF coil is a planar coil in which a first coil part including a first linear region and a second coil part including a second linear region are connected,
The first coil portion and the second coil portion have a conductive wire reversely wound,
The first straight region and the second straight region are arranged in parallel to the extending direction of the groove,
When viewed from the upper part of the flow path forming surface of the permanent magnet, a region sandwiched between the first linear region and the second linear region is included in a single groove forming region, measuring device. The measuring apparatus according to claim 6 or 7,
The RF coil is disposed between the flow path forming surface of the permanent magnet and the film,
An interval adjusting member having a specific thickness made of a nonmagnetic material is disposed between the flow path forming surface of the permanent magnet and the planar coil, and between the planar coil and the film. ,measuring device.   The measuring apparatus according to claim 1, wherein the protic solvent is water.   A fuel cell comprising the measuring device according to claim 1. The fuel cell according to claim 10, wherein
Including a separator provided opposite the fuel electrode or the oxidant electrode,
A fuel cell, wherein the separator includes the permanent magnet. The fuel cell according to claim 11, wherein
The fuel cell in which the flow path forming surface of the permanent magnet is disposed to face the fuel electrode of the fuel cell, and fuel gas is supplied to the flow path groove. The fuel cell according to claim 11, wherein
The fuel cell, wherein the flow path forming surface of the permanent magnet is disposed opposite to the oxidant electrode of the fuel cell, and an oxidant gas is supplied to the flow channel groove. A method of locally measuring the amount of the protic solvent at a specific location in the film by using a nuclear magnetic resonance method by disposing a film in parallel with the flow path forming surface of the permanent magnet in which the flow path groove is formed. There,
While flowing a fluid containing the protic solvent in the flow channel groove of the permanent magnet, a static magnetic field is applied to the film by a permanent magnet, and RF is applied to a part of the film placed in the static magnetic field. A first step of sequentially applying an excitation oscillating magnetic field a plurality of times using a coil and acquiring a plurality of echo signals corresponding to the excitation oscillating magnetic field;
A second step of determining the amount of the protic solvent at a specific location of the membrane from the intensity of the plurality of echo signals;
Including a measuring method. The measurement method according to claim 14,
The second step includes
Calculating a T ₂ relaxation time constant from the intensity of the echo signal;
Data indicating the correlation between the amount of protic solvent in the membrane and the T ₂ relaxation time constant is obtained, and the data and the T ₂ relaxation time constant calculated in the step of calculating the T ₂ relaxation time constant are obtained. Determining the amount of the protic solvent;
Including a measuring method.