JP2018173283A - Field asymmetric ion mobility spectrometer, and mixture separation method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a field asymmetric ion mobility spectrometer having a higher separation capability.SOLUTION: There is provided a field asymmetric ion mobility spectrometer for selectively separating at least one substance from a mixture containing two or more substances. A filter comprised in the spectrometer comprises first to fourth planar electrodes having a main surface parallel to a direction from an ionization device toward the filter. The second planar electrode is positioned between the first planar electrode and the third planar electrode. The third planar electrode is positioned between the second planar electrode and the fourth planar electrode. The third planar electrode and the fourth planar electrode are electrically connected to the first planar electrode and the second planar electrode, respectively. A gap is formed between adjacent twos of the planar electrodes. The electrodes are disposed on a substrate which has a concave-and-convex shape on a surface thereof.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a field asymmetric ion mobility spectrometer and a mixture separation method using the same.

Patent Document 1 and Patent Document 2 disclose an electric field asymmetric ion mobility spectrometer.
Field asymmetric ion mobility spectrometers are used to selectively separate at least one substance from a mixture containing two or more substances. The separated at least one substance is detected by a detector included in the electric field asymmetric ion mobility spectrometer.

Japanese Patent No. 5221954 Japanese Patent No. 5015395

  An object of the present invention is to provide a field asymmetric ion mobility spectrometer having high separation ability.

A field asymmetric ion mobility spectrometer according to the present invention is a field asymmetric ion mobility spectrometer for selectively separating at least one substance from a mixture containing two or more substances,
An ionizer for ionizing two or more kinds of substances contained in the mixture, and a filter for selecting the at least one kind of substance from the two or more kinds of ionized substances;
It comprises.
here,
The filter is adjacent to the ionizer;
The filter includes a first electrode group and a second electrode group,
The filter includes a flat plate-like first electrode, a flat plate-like second electrode, a flat plate-like third electrode, and a flat plate-like fourth electrode,
The first electrode group includes the flat plate-like first electrode and the flat plate-like third electrode,
The second electrode group includes the flat plate-like second electrode and the flat plate-like fourth electrode,
Each of the flat plate-shaped first to fourth electrodes has a main surface parallel to the direction from the ionizer toward the filter,
The plate-like second electrode is located between the plate-like first electrode and the plate-like third electrode,
The plate-like third electrode is located between the plate-like second electrode and the plate-like fourth electrode,
The flat plate-like third electrode is electrically connected to the flat plate-like first electrode,
The flat plate-like fourth electrode is electrically connected to the flat plate-like second electrode,
A first gap is formed between the flat plate-like first electrode and the second electrode,
A second gap is formed between the flat plate-like second electrode and the third electrode,
A third gap is formed between the flat plate-like third electrode and the fourth electrode,
The first electrode group is electrically insulated from the second electrode group;
The filter includes a lower insulating substrate and an upper insulating substrate parallel to each other,
Between the lower insulating substrate and the upper insulating substrate, the plate-like first to fourth electrodes are located,
The normal direction of the flat plate-shaped first to fourth electrodes is orthogonal to the normal line of the lower insulating substrate,
In a cross section including both the normal line of the flat plate-like first electrode and the normal line of the lower insulating substrate, the lower insulating substrate has a lower first recess on the upper surface thereof,
In the cross section, the lower insulating substrate includes a lower first convex portion and a lower second convex portion on an upper surface thereof,
In the cross section, the lower first concave portion is located between the lower first convex portion and the lower second convex portion,
In the cross section, the flat plate-like first electrode is located on the lower first convex portion, and in the cross section, the flat plate-like second electrode is located on the lower second convex portion. ing.

  The gist of the present invention includes a method for selectively separating at least one substance from a mixture containing two or more kinds of substances using the above-described electric field asymmetric ion mobility spectrometer.

  The present invention provides a field asymmetric ion mobility spectrometer with high separation capability.

FIG. 1 shows a schematic diagram of an electric field asymmetric ion mobility spectrometer. FIG. 2 is a graph showing the relationship between electric field strength and ion mobility ratio. FIG. 3 is a schematic diagram of a filter according to the embodiment. FIG. 4A is a graph showing the relationship between the asymmetrical AC voltage applied to the first electrode group and time. FIG. 4B is a graph showing a relationship between an asymmetrical AC voltage applied to the first electrode group and time. FIG. 4C is a graph showing the relationship between the asymmetrical AC voltage applied to the first electrode group and time. FIG. 4D is a graph showing the relationship between the asymmetrical AC voltage applied to the first electrode group and time. FIG. 5 shows a schematic plan view of the movement of two types of ionized gas between a pair of flat electrodes included in a conventional filter. FIG. 6 is a schematic plan view showing movements of two types of ionized gas between the flat plate-like first electrode to the fourth electrode included in the filter according to the embodiment. FIG. 7A is a schematic diagram of one step included in the method of manufacturing a filter according to the embodiment. FIG. 7B is a schematic diagram of one step included in the method for manufacturing the filter according to the embodiment, following FIG. 7A. FIG. 7C is a schematic diagram of one step included in the method for manufacturing the filter according to the embodiment, following FIG. 7B. FIG. 7D is a schematic diagram of one step included in the method for manufacturing the filter according to the embodiment, following FIG. 7C. FIG. 8A shows a plan view of a filter according to an embodiment. FIG. 8B shows a cross-sectional view along line 8B-8B included in FIG. 8A. FIG. 8C shows an enlarged view of a portion surrounded by a broken line included in FIG. 8B. FIG. 8D shows an enlarged view of the portion included in FIG. 8C when there is no lower first recess. FIG. 9A shows a plan view of a filter according to a first modification of the embodiment. FIG. 9B shows a cross-sectional view along line 9B-9B included in FIG. 9A. FIG. 10A is a plan view of a filter according to a second modification of the embodiment. FIG. 10B shows a cross-sectional view along line 10B-10B included in FIG. 10A. FIG. 10C shows a cross-sectional view along line 10C-10C included in FIG. 10A. FIG. 11A is a plan view of a filter according to a third modification of the embodiment. FIG. 11B shows a cross-sectional view along line 11B-11B included in FIG. 11A. FIG. 12A is a plan view of a filter according to a fourth modification of the embodiment. FIG. 12B shows a cross-sectional view along line 12B-12B included in FIG. 12A. FIG. 12C shows a cross-sectional view along line 12C-12C included in FIG. 12A.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention relates to an improvement in the electric field asymmetric ion mobility spectrometer disclosed in Japanese Patent Application No. 2006-217738 (changed to the corresponding US application 15/350155). Japanese Patent Application No. 2006-217738 (in the English specification, changed to the corresponding US application 15/350155) is hereby incorporated by reference.

  First, a field asymmetric ion mobility spectrometer (hereinafter may be referred to as “FAIMS”) will be described. The user prepares FAIMS according to the present embodiment. That is, the user assembles the FAIMS according to the present embodiment. Alternatively, the user purchases FAIMS according to the present embodiment from the patentee or its licensee. Next, the user turns on the FAIMS according to the present embodiment so that the FAIMS can be used.

  Field asymmetric ion mobility spectrometers are used to selectively separate at least one substance from a mixture containing two or more substances.

  FIG. 1 shows a schematic diagram of an electric field asymmetric ion mobility spectrometer. As shown in FIG. 1, the electric field asymmetric ion mobility spectrometer includes an ionizer 301 and a filter 302. Using the ionizer 301, two or more kinds of substances contained in the mixture are ionized. At least one material is selected from the two or more ionized materials via the filter 302.

(Ionizer 301)
The mixture supplied to the ionizer 301 is a liquid or a gas. In this specification, a mixture shall contain three types of gas 202-204. The gases 202 to 204 are ionized using the ionizer 301.

  For details of the ionization apparatus 301, see Patent Document 1 and Patent Document 2. These documents are hereby incorporated by reference.

(Filter 302)
Next, the ionized gases 202 to 204 are supplied to a filter 302 disposed adjacent to the ionizer 301.

  The filter 302 includes a flat plate-like first electrode 201a and a flat plate-like second electrode 201b arranged in parallel to each other. The first electrode 201a is grounded. On the other hand, the second electrode 201 b is connected to the power source 205. The power source 205 is used to apply an asymmetrical AC voltage to the second electrode 201b. A compensation voltage CV can be superimposed on the asymmetrical AC voltage. The asymmetrical AC voltage applied to the second electrode 201b will be described later.

  Three types of ionized gases 202 to 204 are supplied between the grounded first electrode 201a and the second electrode 201b to which an asymmetrical AC voltage is applied. The three types of gases 202 to 204 are affected by the electric field generated between the first electrode 201a and the second electrode 201b.

  FIG. 2 is a graph showing the relationship between electric field strength and ion mobility ratio. As indicated by reference numeral 701 in FIG. 2, some ionized gases move more actively as the electric field strength increases. Ions with a mass-to-charge ratio of less than 300 exhibit this behavior.

  As indicated by reference numeral 702 included in FIG. 2, some ionized gases move more actively when the electric field strength increases, but the degree of movement decreases when the electric field strength is further increased. There is also.

  As indicated by reference numeral 703 included in FIG. 2, some ionized gases have a lower degree of movement as the electric field strength increases. Ions with a mass-to-charge ratio of 300 or more exhibit this behavior.

  Due to such a difference in characteristics, as shown in FIG. 1, three kinds of gases 202 to 204 travel in different directions inside the filter 302. Only the gas 203 is exhausted from the filter 302, while the gas 202 is trapped on the surface of the first electrode 201a and the gas 204 is trapped on the surface of the second electrode 201b. In this way, only the gas 203 is selectively separated from the three types of gases. In other words, only the gas 203 is exhausted from the filter 302.

  The intensity of the electric field is appropriately set depending on the type of ions to be separated.

  Next, features of the electric field asymmetric ion mobility spectrometer according to the present embodiment will be described below.

  The electric field asymmetric ion mobility spectrometer according to the present embodiment is characterized by the structure of the filter 302.

  FIG. 3 is a schematic diagram of the filter 302 according to the present embodiment. As shown in FIG. 3, the filter 302 includes a first electrode group 102 and a second electrode group 103. Needless to say, the filter 302 according to the present embodiment is included in the electric field asymmetric ion mobility spectrometer.

  The filter 302 includes a flat plate-like first electrode 106a, a flat plate-like second electrode 106b, a flat plate-like third electrode 106c, and a flat plate-like fourth electrode 106d.

  The first electrode group 102 includes a flat plate-like first electrode 106a and a flat plate-like third electrode 106c. The second electrode group 103 includes a flat second electrode 106b and a flat fourth electrode 106d. Inside the filter 302, the first electrode group 102 is electrically insulated from the second electrode group 103.

  Each of the flat plate-like first to fourth electrodes 106a to 106d has a main surface parallel to the direction from the ionizer 301 toward the filter 302 (that is, the flow direction of the mixture). The black arrows included in FIG. 3 indicate the flow direction of the mixture (that is, the direction from the ionizer 301 toward the filter 302).

  As shown in FIG. 3, the flat plate-like second electrode 106b is located between the flat plate-like first electrode 106a and the flat plate-like third electrode 106c. The plate-like third electrode 106c is located between the plate-like second electrode 106b and the plate-like fourth electrode 106f.

  The filter 302 shown in FIG. 1 further includes a plate-like fifth electrode 106e and a plate-like sixth electrode 106f. The flat fifth electrode 106 e is included in the first electrode group 102. The flat plate-like sixth electrode 106 f is included in the second electrode group 103.

  The filter 103 can include a larger number of flat electrodes 106. The plate-shaped n-th electrode 106 is located between the plate-shaped (n−1) -th electrode 106 and the plate-shaped (n + 1) -th electrode 106 (n represents a natural number of 2 or more). The plate-shaped nth electrode 106 has a main surface parallel to the direction from the ionizer 301 toward the filter 302 (that is, the flow direction of the mixture). The first electrode group 102 includes a flat second m-1 electrode 106 (m represents an integer of 1 or more). The second electrode group 103 includes a flat second m electrode 106.

  A gap 108 is formed between two adjacent flat electrodes 106. Specifically, a first gap 108a is formed between the flat first electrode 106a and the flat second electrode 106b. Similarly, a second gap 108b is formed between the flat second electrode 106b and the flat third electrode 106c. A third gap 108c is formed between the flat third electrode 106c and the flat fourth electrode 106d.

  Hereinafter, a method for selectively separating at least one substance from a mixture containing two or more kinds of substances in the filter 302 according to the present embodiment will be described. Hereinafter, the mixture contains two types of gases 202 to 203.

  Gases 202 to 203 ionized by the ionizer 301 are supplied to the filter 302. While the second electrode group 103 is grounded, an asymmetrical AC voltage is applied to the first electrode group 102 from the power source 205.

  FIG. 4A is a graph showing the relationship between the asymmetrical AC voltage applied to the first electrode group 102 and time. In FIG. 4A, the compensation voltage is 0 volts. During the period t1, the positive voltage V1 (> 0) is applied to the first electrode group 102. During the period t2, the negative voltage V2 (<0) is applied to the first electrode group 102. This is repeated. The area S1 defined by the product V1 · t1 is equal to the area S2 defined by the product | V2 | · t2.

  Desirably, time t1 is 6 nanoseconds or more and 100 nanoseconds or less. Desirably, positive voltage V1 is 67.5 volts or more and 118.125 volts or less, and negative voltage V2 is 16 volts or more and 28.4 volts or less. Generally, the absolute value of the positive voltage V1 is larger than the absolute value of the negative voltage V2. However, as shown in FIGS. 4C and 4D, the absolute value of the positive voltage V1 may be smaller than the absolute value of the negative voltage V2. Desirably, the asymmetrical AC voltage has a frequency of 2 MHz to 30 MHz.

  The asymmetrical AC voltage shown in FIG. 4A is a rectangular wave. However, instead of the rectangular wave, the asymmetrical AC voltage may be a sine wave.

  FIG. 4B is also a graph showing the relationship between the asymmetrical AC voltage applied to the first electrode group 102 and time. In FIG. 4B, the compensation voltage CV is superimposed on the asymmetrical AC voltage. The duty ratio of the asymmetrical AC voltage while keeping the frequency constant so that the area S3 defined by the product (V1 + CV) · t1 ′ is equal to the area S4 defined by the product | −V2 + CV | · t2 ′ Is adjusted. Desirably, the compensation voltage CV is -20 volts or more and +20 volts or less.

  FIG. 5 shows a schematic plan view of the movement of two kinds of ionized gases 902 to 903 between a pair of flat electrodes 900a and 900b included in a conventional filter. The flat electrode 900 a is grounded, and the flat electrode 900 b is electrically connected to the power source 205. The arrows included in FIG. 5 indicate the flow direction of the mixture (that is, the direction from the ionizer 301 toward the filter 302).

  As shown in FIG. 5, in the period t1, the ionized gases 902 and 903 are attracted toward the flat electrode 900b. On the other hand, in the period t2, the ionized gases 902 and 903 are attracted toward the flat electrode 900a. For gas 903, the lateral travel distance in period t1 is substantially equal to the lateral travel distance in period t2. On the other hand, for the gas 902, the lateral movement distance in the period t1 is larger than the lateral movement distance in the period t2. Accordingly, the gas 903 travels along the pair of flat electrodes 900 a and 900 b, while the gas 902 is trapped on the surface of the flat electrode 900.

  However, when the electric field applied to the gas 902 in the period t1 is too small, when the length of the electrodes 900 is too short, or when the distance between the electrodes 900 is too large, the gas 902 is formed on the surface of the flat electrode 900. Not trapped. In other words, the gas 902 is exhausted from the filter together with the gas 903. As a result, gas 902 is not separated from the mixture containing gas 902 and gas 903. Thus, the conventional filter shown in FIG. 5 has a low separation capability.

  On the other hand, FIG. 6 shows a schematic plan view of the movement of the two types of ionized gases 202 to 203 between the flat plate-like first electrode 106a to the fourth electrode 104d included in the filter 302 according to the present embodiment. As described above, the flat plate-like first electrode 106 a and the flat plate-like third electrode 106 c are electrically connected to the power source 205. On the other hand, the flat plate-like second electrode 106b and the flat plate-like fourth electrode 106d are grounded.

  In the period t1, the ionized gases 202 and 203 are directed toward one of the flat electrodes included in the first electrode group 102 (that is, the flat first electrode 106a or the flat third electrode 106c). Gravitate. On the other hand, in the period t2, the ionized gases 202 and 203 are supplied to one of the flat electrodes included in the second electrode group 103 (that is, the flat second electrode 106b or the flat fourth electrode 106d). It is drawn towards.

  For gas 203, the lateral travel distance in period t1 is substantially equal to the lateral travel distance in period t2. On the other hand, for the gas 202, the lateral movement distance in the period t1 is larger than the lateral movement distance in the period t2.

  As is clear from comparison of FIG. 6 with FIG. 5, the ionized gas 202 is flat even when the electric field applied to the gas 202 is small in the period t1 or when the length of the flat electrode 106 is short. While being trapped on the surface of the electrode 106, the ionized gas 203 travels straight through the filter 302 along the plate electrode 106 and is discharged from the filter 302. As described above, at least one target ion (that is, the ionized gas 203) is efficiently separated from the mixture containing two or more types of ions using the filter 302 according to the present embodiment. The Thus, the filter according to the present embodiment shown in FIG. 6 has a high separation capability.

  Depending on the nature of the intended ionized gas (ie, ionized gas 203), the electric field applied to the gas is adjusted. As an example, in the filter 302 according to the present embodiment, the distance 801 between two adjacent planar electrodes 106 may be 10 micrometers or more and 35 micrometers or less. The length of the flat electrode 106 may be 300 micrometers or more and 10,000 micrometers or less. In the period t1, an electric field of 20000 volts / cm or more and 70000 volts / cm or less can be applied to the gas. In the period t2, an electric field of 1000 volts / cm or more and 10,000 volts / cm or less can be applied to the gas.

  The filter 302 according to the present embodiment will be described more specifically below.

  As shown in FIG. 3, the filter 302 has a rectangular parallelepiped shape. The filter 302 preferably includes a lower insulating substrate 101 and an upper insulating substrate 105 that are parallel to each other. A plate-like electrode 106 is located between the lower insulating substrate 101 and the upper insulating substrate 105. Each of the flat electrodes 106 has a normal line orthogonal to the thickness direction of the lower insulating substrate 101 (that is, the vertical direction on the paper surface). Furthermore, each flat electrode 106 has a main surface parallel to the flow direction of the mixture (that is, the direction from the ionizer 301 to the filter 302).

  Thus, the flat electrode 106 is provided between the lower insulating substrate 101 and the upper insulating substrate 105 so as to stand in the vertical direction on the lower insulating substrate 101.

  A first strip electrode 112 and a second strip electrode 114 are provided on the lower surface of the upper insulating substrate 105. The first strip electrode 112 is included in the first electrode group 102 and has a plate-like second m-1 electrode 106 (for example, a plate-like first electrode 106a, a plate-like third electrode 106c, and a plate-like shape). The fifth electrode 106e) is electrically connected. The second strip electrode 114 is included in the second electrode group 103 and has a flat plate-like second m electrode 106 (for example, a flat plate-like second electrode 106b, a flat plate-like fourth electrode 106d, and a flat plate-like second electrode 106d). 6 electrodes 106f) are electrically connected. As shown in FIG. 3, the first strip electrode 112 and the second strip electrode 114 extend in a direction parallel to the normal line of the flat plate-like first electrode 106a (that is, the horizontal direction on the paper surface). Is desirable.

  Thus, it is desirable that the first electrode group 102 and the second electrode group 103 have a comb shape. In plan view, the first electrode group 102 and the second electrode group 103 having a comb shape are engaged with each other.

  The first electrode group 102 preferably includes a first wall surface electrode 122 positioned at one end (the left end on the paper surface) of the filter 302. Similarly, the second electrode group 103 preferably includes a second wall surface electrode 124 positioned at the other end of the filter 302 (the right end on the paper surface). Needless to say, a pair of openings are provided on the other two side surfaces of the filter 302 (the front side and the rear side on the paper surface). The mixture enters the interior of the filter 302 through one opening (the rear opening on the paper). At least one substance of interest is discharged from the filter 302 through the other opening (front opening on the paper surface).

  The upper insulating substrate 105 is provided with a first through hole 106 and a second through hole 107. The first wall electrode 122 is electrically connected to the power source 205 through the first through hole 106. Similarly, the second wall electrode 124 is grounded through the second through hole 107.

  In the period t1, a very high voltage is applied between two adjacent electrodes 106. Therefore, creeping discharge can occur along the surface of the lower insulating substrate 101 between two adjacent flat electrodes 106. In the present embodiment, the lower first concave portion is provided on the upper surface of the lower insulating substrate 101. The said lower 1st recessed part suppresses creeping discharge.

  Hereinafter, the lower insulating substrate 101 according to the present embodiment will be described in detail. FIG. 8A shows a plan view of a filter 302 according to an embodiment. This plan view includes the first electrode 106a to the sixth electrode 106f. FIG. 8B shows a cross-sectional view along line 8B-8B included in FIG. 8A. The cross-sectional view shown in FIG. 8B is also a front view of the filter 302.

  The arrow X included in FIG. 3 is parallel to the normal line of the flat plate-like first electrode 106a (that is, the left-right direction on the paper). The arrow Y is parallel to the flow direction of the mixture (that is, the front and back direction on the paper). The arrow Z is parallel to the normal line of the lower insulating substrate 101 (that is, the vertical direction on the paper surface). FIG. 8A appears when the filter 302 is cut along a plane including the arrows X and Y. FIG. 8B appears when the filter 302 is cut along a plane including the arrows X and Z.

  As shown in FIG. 8B, the lower insulating substrate 101 includes a lower first recess 131a, a lower second recess 131b, a lower third recess 131c, a lower fourth recess 131d, and a lower fifth recess. 131e is provided on the upper surface. Further, the lower insulating substrate 101 includes a lower first convex portion 141a, a lower second convex portion 141b, a lower third convex portion 141c, a lower fourth convex portion 141d, a lower fifth convex portion 141e, The lower sixth convex portion 141f is provided on the upper surface. The lower first concave portion 131a is located between the lower first convex portion 141a and the lower second convex portion 141b. The lower second concave portion 131b is located between the lower second convex portion 141b and the lower third convex portion 141c.

  The first electrode 106a is located on the lower first convex portion 141a. Desirably, one side surface of the first electrode 106a having a thin rectangular parallelepiped shape is in contact with the lower first convex portion 141a. Similarly, the second electrode 106b to the sixth electrode 106e are positioned on the lower second convex portion 141b to the lower sixth convex portion 141f, respectively.

  Although not shown, similarly, the upper insulating substrate 105 also includes an upper first concave portion to an upper fifth concave portion and an upper first convex portion to an upper sixth convex portion on the lower surface.

  As shown in FIG. 3, each recess 131 has a groove shape parallel to the arrow Y.

  FIG. 8C shows an enlarged view of a portion surrounded by a broken line included in FIG. 8B. FIG. 8D shows an enlarged view of the portion where there is no lower first recess 131a. As indicated by the arrow L2 included in FIG. 8D, creeping discharge may occur along the surface of the lower insulating substrate 101 between two adjacent flat electrodes 106. On the other hand, in the present embodiment, as indicated by an arrow L1 included in FIG. 8C, the surface of the lower insulating substrate 101 between the two adjacent flat electrodes 106 because of the lower first recess 131a. The distance L1 along is longer as compared with the case where there is no lower first recess 131a. In other words, the distance L1 is longer than the distance L2. For this reason, the possibility of occurrence of creeping discharge is reduced.

  As an example, when the depth D (see FIG. 8C) of the lower first recess 131a is 5 micrometers or more, the electric field strength between two adjacent electrodes 106 even when a voltage of 70000 volts / cm is applied. Does not exceed the threshold for creeping discharge. Depth D can be 10 micrometers or less. The recess 131 having a depth D of 10 micrometers or less can be formed by the Bosch method.

  FIG. 9A shows a plan view of a filter according to a first modification of the embodiment. FIG. 9B shows a cross-sectional view along line 9B-9B included in FIG. 9A. As shown in FIG. 9B, two or more grooves may be formed between the lower first convex portion 141a and the lower second convex portion 141b. In other words, the lower insulating substrate 101 includes not only the lower first recess 131a to the lower fifth recess 131e but also the lower first additional recess 151a to the lower fifth additional recess 151e on the upper surface. Yes. Although not shown, the upper insulating substrate 105 may also include such an additional recess on the lower surface.

  FIG. 10A is a plan view of a filter according to a second modification of the embodiment. FIG. 10B shows a cross-sectional view along line 10B-10B included in FIG. 10A. FIG. 10C shows a cross-sectional view along line 10C-10C included in FIG. 10A. 10B, the lower recess 131 is provided, but in FIG. 10C, the lower recess 131 is not provided. That is, the length L3 of the groove (that is, the recess 131 in the cross-sectional view) in plan view may be smaller than the length L4 of the short side of the lower insulating substrate 101. As described above, the lower concave portion 131 can be provided only in a portion where creeping discharge is required to be suppressed. The upper insulating substrate 105 may also have a structure similar to the structure shown in FIGS. 10A to 10C.

  FIG. 11A is a plan view of a filter according to a third modification of the embodiment. FIG. 11B shows a cross-sectional view along line 11B-11B included in FIG. 11A. As shown in FIG. 11A, in the plan view, the distance between the first electrode 106a and the second electrode 106b may be different from the distance between the second electrode 106b and the third electrode 106c. Similarly to the case of the second modification example shown in FIGS. 10A to 10C, in the third modification example shown in FIGS. 11A and 11B, a portion where suppression of creeping discharge is required (for example, between adjacent electrodes 106). The lower concave portion 131 can be provided only in a portion where the interval is particularly narrow.

  FIG. 12A is a plan view of a filter according to a fourth modification of the embodiment. FIG. 12B shows a cross-sectional view along line 12B-12B included in FIG. 12A. FIG. 12C shows a cross-sectional view along line 12C-12C included in FIG. 12A. The electric field strength generated at one end of the electrode 106 may be different from the electric field strength generated at the center of the electrode 106. Specifically, the electric field tends to concentrate locally at one end of the electrode 106. Therefore, as shown in FIGS. 12A to 12C, a lower recess 131 can be formed at one end of the electrode 106. As shown in FIG. 12A, a lower additional recess 151 may be formed at the other end of the electrode 106. Similarly, an upper concave portion (not shown) and an upper additional convex portion (not shown) can be formed at one end of the electrode 106.

  Hereinafter, a method for manufacturing the filter 302 according to the present embodiment will be described.

  First, as shown in FIG. 7A, a silicon substrate 501 having a gold layer (not shown) on the surface is formed on a lower insulating substrate 101 such as a glass substrate having an aluminum layer (not shown) on the surface. Lamination is performed to form a layer / aluminum layer / silicon layer / gold layer laminate. The silicon substrate 501 may have a thickness of 300 micrometers or more and 700 micrometers or less. The silicon substrate 501 is doped with an impurity such as antimony. Therefore, the silicon substrate 501 has conductivity. The gold layer can be formed by coating the lower insulating substrate 101 with gold by sputtering or vapor deposition. The gold layer can have a thickness of 200 nanometers or more and 300 nanometers or less. The aluminum layer can be formed by coating a silicon substrate doped with an impurity such as antimony with aluminum by sputtering or vapor deposition. The aluminum layer can have a thickness of approximately 1 micrometer. A silicon substrate 501 having an aluminum layer on its surface is bonded to the lower insulating substrate 101 by an anodic bonding method.

  Next, a photoresist is applied on the gold layer exposed on the outermost surface. The photoresist is exposed using a mask to form a resist pattern (not shown). A part of the gold layer is removed by wet etching using the resist pattern as a mask. Further, a part of the silicon layer is removed by the Bosch method using the resist pattern as a mask. A part of the aluminum layer is removed using the resist pattern as a mask. In this manner, the plate-like electrode 106, the first wall surface electrode 122, and the second wall surface electrode 124 are formed on the lower insulating substrate 101.

Thereafter, as shown in FIG. 7C, the glass layer is further etched. Using the flat electrode 106, the first wall surface electrode 122, and the second wall surface electrode 124 as a mask and using a fluorocarbon gas such as tetrafluoromethane represented by the chemical formula CF ₄ , the glass layer has a thickness direction. Is etched along. In this way, the lower recess 131 is formed between the two adjacent electrodes 106.

  Alternatively, the lower recess 131 can be formed on the glass substrate before the silicon substrate 501 is laminated on the glass substrate. In this case, a photoresist layer is formed on the surface of the glass substrate. Next, only a portion where the lower recess 131 is formed is removed by a development process by a photolithography technique. Using the photoresist layer left on the glass substrate as a mask, the surface of the glass substrate is etched to form the lower recess 131. The photoresist layer is removed through a remover process and an oxygen ashing process. Next, a silicon substrate 501 is laminated on the glass substrate. Thereafter, the electrode 106 is formed according to the above process. An upper recess (not shown) can be formed on the lower surface of the upper insulating substrate 105 in this manner. Needless to say, alignment (ie, alignment) is performed if necessary for forming the photoresist layer and forming the recesses.

  Finally, as shown in FIG. 7D, the upper insulating substrate 105 having the first strip electrode 112 and the second strip electrode 114 on the lower surface is bonded onto the lower insulating substrate 101. At the time of bonding, the first strip electrode 112 is electrically connected to the plate-like second m-1 electrode 106 (for example, the plate-like first electrode 106a, the plate-like third electrode 106c, and the plate-like fifth electrode 106e). Connected to. Similarly, the second strip electrode 114 is electrically connected to the plate-like second m electrode 106 (for example, the plate-like second electrode 106b, the plate-like fourth electrode 106d, and the plate-like sixth electrode 106f). Is done. In this way, the filter 302 shown in FIG. 3 is obtained.

(Other)
(Ion detector)
As shown in FIG. 1, the electric field asymmetric ion mobility spectrometer can include an ion detector 303. The ion detector 303 is disposed adjacent to the filter 302. In other words, the filter 302 is disposed between the ionizer 301 and the ion detector 303.

  A known ion detector 303 as disclosed in Patent Document 1 and Patent Document 2 can be used. At least one substance (that is, gas 203) that has passed through the filter 302 is detected by the ion detector 303. At least one kind of substance (that is, the gas 203) that has reached the ion detection unit 303 delivers charges to the electrode 310 included in the ion detection unit 303. The ammeter 311 measures the value of the current that flows in proportion to the amount of charge delivered. The gas 203 is identified based on the value of the current measured by the ammeter.

(Pump or electrostatic field)
As shown in FIG. 1, the field asymmetric ion mobility spectrometer may comprise a pump 304. By the pump 304, the mixture is sucked from the ionizer 301 through the filter 302 to the ion detector 303.

  Instead of the pump 304, an electrostatic field can be used. In other words, the mixture can flow from the ionizer 301 through the filter 302 to the ion detector 303 by the electrostatic field. In this case, the electric field asymmetric ion mobility spectrometer includes a pair of electrodes (not shown). An ionizer 301, a filter 302, and an ion detector 303 are sandwiched between the pair of electrodes. A DC voltage is applied to the pair of electrodes. The ionized mixture can flow from the ionizer 301 to the ion detector 303 through the filter 302 by a DC voltage applied between the pair of electrodes.

  The electric field asymmetric ion mobility spectrometer according to the present invention can be used for detecting a component contained in a biological gas released from a living body or for detecting a dangerous component contained in an environmental gas.

101 Lower insulating substrate 102 First electrode group 103 Second electrode group 105 Upper insulating substrate 106a Flat plate-like first electrode 106b Flat plate-like second electrode 106c Flat plate-like third electrode 106d Flat plate-like fourth electrode 106e Flat fifth electrode 106f Flat sixth electrode 108a First gap 108b Second gap 108c Third gap

112 1st strip electrode 114 2nd strip electrode 122 1st wall electrode 124 2nd wall electrode

131a Lower first recess 131b Lower second recess 131c Lower third recess 131d Lower fourth recess 131e Lower fifth recess

141a Lower first convex portion 141b Lower second convex portion 141c Lower third convex portion 141d Lower fourth convex portion 141e Lower fifth convex portion 141f Lower sixth convex portion

151a Lower first additional recess 151b Lower second additional recess 151c Lower third additional recess 151d Lower fourth additional recess 151a Lower fifth additional recess

201a Flat first electrode 201b Flat second electrode 202 Gas 203 Gas 204 Gas 205 Power supply

301 Ionizer 302 Filter 303 Ion Detector 304 Pump 311 Ammeter

900a Flat electrode 900b Flat electrode 902 Gas 903 Gas

Claims (40)

A field asymmetric ion mobility spectrometer for selectively separating at least one substance from a mixture containing two or more substances, comprising:
An ionizer for ionizing two or more kinds of substances contained in the mixture, and a filter for selecting the at least one kind of substance from the two or more kinds of ionized substances;
here,
The filter is adjacent to the ionizer;
The filter includes a first electrode group and a second electrode group,
The filter includes a flat plate-like first electrode, a flat plate-like second electrode, a flat plate-like third electrode, and a flat plate-like fourth electrode,
The first electrode group includes the flat plate-like first electrode and the flat plate-like third electrode,
The second electrode group includes the flat plate-like second electrode and the flat plate-like fourth electrode,
Each of the flat plate-shaped first to fourth electrodes has a main surface parallel to the direction from the ionizer toward the filter,
The plate-like second electrode is located between the plate-like first electrode and the plate-like third electrode,
The plate-like third electrode is located between the plate-like second electrode and the plate-like fourth electrode,
The flat plate-like third electrode is electrically connected to the flat plate-like first electrode,
The flat plate-like fourth electrode is electrically connected to the flat plate-like second electrode,
A first gap is formed between the flat plate-like first electrode and the second electrode,
A second gap is formed between the flat plate-like second electrode and the third electrode,
A third gap is formed between the flat plate-like third electrode and the fourth electrode,
The first electrode group is electrically insulated from the second electrode group;
The filter includes a lower insulating substrate and an upper insulating substrate parallel to each other,
Between the lower insulating substrate and the upper insulating substrate, the plate-like first to fourth electrodes are located,
The normal direction of the flat plate-shaped first to fourth electrodes is orthogonal to the normal line of the lower insulating substrate,
In a cross section including both the normal line of the flat plate-like first electrode and the normal line of the lower insulating substrate, the lower insulating substrate has a lower first recess on the upper surface thereof,
In the cross section, the lower insulating substrate includes a lower first convex portion and a lower second convex portion on an upper surface thereof,
In the cross section, the lower first concave portion is located between the lower first convex portion and the lower second convex portion,
In the cross section, the flat plate-like first electrode is located on the lower first convex portion, and in the cross section, the flat plate-like second electrode is located on the lower second convex portion. ing,
Electric field asymmetric ion mobility spectrometer. The electric field asymmetric ion mobility spectrometer according to claim 1,
In the cross section, a lower second recess is provided on the upper surface of the lower insulating substrate,
In the cross section, a lower third convex portion is provided on the upper surface of the lower insulating substrate,
In the cross section, the lower second concave portion is located between the lower second convex portion and the lower third convex portion, and in the cross section, on the lower third convex portion, A plate-like third electrode is located,
Electric field asymmetric ion mobility spectrometer. The field asymmetric ion mobility spectrometer according to claim 2,
In the cross section, a lower third recess is provided on the upper surface of the lower insulating substrate,
In the cross section, a lower fourth convex portion is provided on the upper surface of the lower insulating substrate,
In the cross section, the lower third concave portion is located between the lower third convex portion and the lower fourth convex portion, and in the cross section, on the lower fourth convex portion, A flat fourth electrode is located,
Electric field asymmetric ion mobility spectrometer. The electric field asymmetric ion mobility spectrometer according to claim 1,
In the cross section, an upper first recess is provided on a lower surface of the upper insulating substrate,
In the cross section, an upper first convex portion and an upper second convex portion are provided on the lower surface of the upper insulating substrate,
In the cross section, the upper first concave portion is located between the upper first convex portion and the upper second convex portion,
In the cross section, the upper first convex portion is located on the flat plate-like first electrode, and in the cross section, the upper second convex portion is located on the flat plate-like second electrode. ing,
Electric field asymmetric ion mobility spectrometer. The field asymmetric ion mobility spectrometer according to claim 4,
In the cross section, an upper second concave portion is provided on the lower surface of the upper insulating substrate,
In the cross section, an upper third convex portion is provided on the lower surface of the upper insulating substrate,
In the cross section, the upper second concave portion is located between the upper second convex portion and the upper third convex portion, and in the cross section, the upper third convex portion is the flat plate-like third. Located on the electrode,
Electric field asymmetric ion mobility spectrometer. The electric field asymmetric ion mobility spectrometer according to claim 5,
In the cross section, an upper third recess is provided on the lower surface of the upper insulating substrate,
In the cross section, an upper fourth convex portion is provided on the lower surface of the upper insulating substrate,
In the cross section, the upper third concave portion is located between the upper third convex portion and the upper fourth convex portion, and in the cross section, the upper fourth convex portion is the flat plate-shaped fourth. Located on the electrode, The electric field asymmetric ion mobility spectrometer according to claim 1,
In the cross section, a lower first additional recess is provided on the upper surface of the lower insulating substrate,
And in the cross section, the lower first additional concave portion is located between the lower first convex portion and the lower second convex portion,
Electric field asymmetric ion mobility spectrometer. The electric field asymmetric ion mobility spectrometer according to claim 1,
In another cross section including both the normal line of the flat plate-like first electrode and the normal line of the lower insulating substrate, the lower first concave portion does not appear.
Electric field asymmetric ion mobility spectrometer. The electric field asymmetric ion mobility spectrometer according to claim 1,
The first electrode group includes a first strip electrode,
The second electrode group includes a second strip electrode,
The first strip electrode is provided on at least one of a lower surface of the upper insulating substrate or an upper surface of the lower insulating substrate,
The second strip electrode is provided on at least one of the lower surface of the upper insulating substrate or the upper surface of the lower insulating substrate,
The first strip electrode is electrically connected to the flat first electrode and the flat third electrode, and the second strip electrode is the flat second electrode and the flat plate. Electrically connected to the fourth electrode of
Electric field asymmetric ion mobility spectrometer. The field asymmetric ion mobility spectrometer according to claim 2,
The first strip electrode and the second strip electrode extend in a direction parallel to the normal line of the flat plate-like first electrode,
Electric field asymmetric ion mobility spectrometer. The electric field asymmetric ion mobility spectrometer according to claim 1, further comprising a detection unit for detecting the at least one kind of substance selected by the filter,
The filter is located between the ionizer and the detector;
Electric field asymmetric ion mobility spectrometer. The electric field asymmetric ion mobility spectrometer according to claim 1,
The lower first recess has a depth of 5 micrometers to 10 micrometers,
Electric field asymmetric ion mobility spectrometer. The electric field asymmetric ion mobility spectrometer according to claim 1,
The first gap, the second gap, and the third gap all have a width of 10 micrometers to 35 micrometers,
Electric field asymmetric ion mobility spectrometer. The electric field asymmetric ion mobility spectrometer according to claim 1,
Each of the flat plate-like first electrode to fourth electrode has a length of 300 micrometers to 10,000 micrometers,
Electric field asymmetric ion mobility spectrometer. A method for selectively separating at least one substance from a mixture containing two or more substances using a field asymmetric ion mobility spectrometer, comprising:
Providing the field asymmetric ion mobility spectrometer comprising: (a)
An ionizer for ionizing two or more kinds of substances contained in the mixture, and a filter for selecting the at least one kind of substance from the two or more kinds of ionized substances;
here,
The filter is adjacent to the ionizer;
The filter includes a first electrode group and a second electrode group,
The filter includes a flat plate-like first electrode, a flat plate-like second electrode, a flat plate-like third electrode, and a flat plate-like fourth electrode,
The first electrode group includes the flat plate-like first electrode and the flat plate-like third electrode,
The second electrode group includes the flat plate-like second electrode and the flat plate-like fourth electrode,
Each of the flat plate-shaped first to fourth electrodes has a main surface parallel to the direction from the ionizer toward the filter,
The plate-like second electrode is located between the plate-like first electrode and the plate-like third electrode,
The plate-like third electrode is located between the plate-like second electrode and the plate-like fourth electrode,
The flat plate-like third electrode is electrically connected to the flat plate-like first electrode,
The flat plate-like fourth electrode is electrically connected to the flat plate-like second electrode,
A first gap is formed between the flat first electrode and the second electrode, and a second gap is formed between the flat second electrode and the third electrode. A third gap is formed between the third electrode and the fourth electrode, and the first electrode group is electrically insulated from the second electrode group,
The filter includes a lower insulating substrate and an upper insulating substrate parallel to each other,
Between the lower insulating substrate and the upper insulating substrate, the plate-like first to fourth electrodes are located,
The normal direction of the flat plate-shaped first to fourth electrodes is orthogonal to the normal line of the lower insulating substrate,
In a cross section including both the normal line of the flat plate-like first electrode and the normal line of the lower insulating substrate, the lower insulating substrate has a lower first recess on the upper surface thereof,
In the cross section, the lower insulating substrate includes a lower first convex portion and a lower second convex portion on an upper surface thereof,
In the cross section, the lower first concave portion is located between the lower first convex portion and the lower second convex portion,
In the cross section, the flat plate-like first electrode is located on the lower first convex portion, and in the cross section, the flat plate-like second electrode is located on the lower second convex portion. And
Supplying a mixture containing the two or more substances to the ionizer, ionizing the two or more substances contained in the mixture, and (b) filtering the two or more ionized substances into the filter And c) separating the at least one substance through the filter;
Comprising
here,
An asymmetrical alternating voltage is applied between the first electrode group and the second electrode group, and the ionized at least one kind of substance passes through the first to third gaps, while the other ionized substance is ionized. The substance is trapped on the main surface of the flat plate-shaped first to fourth electrodes.
Method. 16. A method according to claim 15, comprising
In the cross section, a lower second recess is provided on the upper surface of the lower insulating substrate,
In the cross section, a lower third convex portion is provided on the upper surface of the lower insulating substrate,
In the cross section, the lower second concave portion is located between the lower second convex portion and the lower third convex portion, and in the cross section, on the lower third convex portion, A plate-like third electrode is located,
Method. The method according to claim 16, comprising:
In the cross section, a lower third recess is provided on the upper surface of the lower insulating substrate,
In the cross section, a lower fourth convex portion is provided on the upper surface of the lower insulating substrate,
In the cross section, the lower third concave portion is located between the lower third convex portion and the lower fourth convex portion, and in the cross section, on the lower fourth convex portion, A flat fourth electrode is located,
Method. 16. A method according to claim 15, comprising
In the cross section, an upper first recess is provided on a lower surface of the upper insulating substrate,
In the cross section, an upper first convex portion and an upper second convex portion are provided on the lower surface of the upper insulating substrate,
In the cross section, the upper first concave portion is located between the upper first convex portion and the upper second convex portion,
In the cross section, the upper first convex portion is located on the flat plate-like first electrode, and in the cross section, the upper second convex portion is located on the flat plate-like second electrode. ing,
Method. The method according to claim 18, comprising:
In the cross section, an upper second concave portion is provided on the lower surface of the upper insulating substrate,
In the cross section, an upper third convex portion is provided on the lower surface of the upper insulating substrate,
In the cross section, the upper second concave portion is located between the upper second convex portion and the upper third convex portion, and in the cross section, the upper third convex portion is the flat plate-like third. Located on the electrode,
Method. 20. The method according to claim 19, comprising
In the cross section, an upper third recess is provided on the lower surface of the upper insulating substrate,
In the cross section, an upper fourth convex portion is provided on the lower surface of the upper insulating substrate,
In the cross section, the upper third concave portion is located between the upper third convex portion and the upper fourth convex portion, and in the cross section, the upper fourth convex portion is the flat plate-shaped fourth. Located on the electrode, 16. A method according to claim 15, comprising
In the cross section, a lower first additional recess is provided on the upper surface of the lower insulating substrate,
And in the cross section, the lower first additional concave portion is located between the lower first convex portion and the lower second convex portion,
Method. 16. A method according to claim 15, comprising
In another cross section including both the normal line of the flat plate-like first electrode and the normal line of the lower insulating substrate, the lower first concave portion does not appear.
Method. 16. A method according to claim 15, comprising
The first electrode group includes a first strip electrode,
The second electrode group includes a second strip electrode,
The first strip electrode is provided on at least one of a lower surface of the upper insulating substrate or an upper surface of the lower insulating substrate,
The second strip electrode is provided on at least one of the lower surface of the upper insulating substrate or the upper surface of the lower insulating substrate,
The first strip electrode is electrically connected to the flat first electrode and the flat third electrode, and the second strip electrode is the flat second electrode and the flat plate. Electrically connected to the fourth electrode of
Method. 24. The method of claim 23, comprising:
The first strip electrode and the second strip electrode extend in a direction parallel to the normal line of the flat plate-like first electrode,
Method. 24. The method of claim 23, comprising:
The electric field asymmetric ion mobility spectrometer further includes a detection unit for detecting the at least one substance selected by the filter, and the filter is interposed between the ionization device and the detection unit. positioned,
Method. 16. A method according to claim 15, comprising
The lower first recess has a depth of 5 micrometers to 10 micrometers,
Method. 16. A method according to claim 15, comprising
The first gap, the second gap, and the third gap all have a width of 10 micrometers to 35 micrometers,
Method. 16. A method according to claim 15, comprising
Each of the flat plate-like first electrode to fourth electrode has a length of 300 micrometers to 10,000 micrometers,
Method. A filter used for a field asymmetric ion mobility spectrometer that selectively separates at least one substance from a mixture containing two or more substances, comprising:
A flat first electrode,
A plate-like second electrode;
A plate-like third electrode, and a plate-like fourth electrode, wherein
The flat plate-like first electrode and the flat plate-like third electrode are included in the first electrode group,
The flat plate-like second electrode and the flat plate-like fourth electrode are included in the second electrode group,
Each of the flat plate-shaped first to fourth electrodes has a main surface parallel to the direction from the ionizer toward the filter,
The plate-like second electrode is located between the plate-like first electrode and the plate-like third electrode,
The plate-like third electrode is located between the plate-like second electrode and the plate-like fourth electrode,
The flat plate-like third electrode is electrically connected to the flat plate-like first electrode,
The flat plate-like fourth electrode is electrically connected to the flat plate-like second electrode,
A gap is formed between the flat plate-shaped first to fourth electrodes,
The first electrode group is electrically insulated from the second electrode group;
The filter includes a lower insulating substrate and an upper insulating substrate parallel to each other,
Between the lower insulating substrate and the upper insulating substrate, the plate-like first to fourth electrodes are located,
The normal direction of the flat plate-shaped first to fourth electrodes is orthogonal to the thickness direction of the lower insulating substrate,
In a cross section including both the normal line of the flat plate-like first electrode and the normal line of the lower insulating substrate, the lower insulating substrate has a lower first recess on the upper surface thereof,
In the cross section, the lower insulating substrate includes a lower first convex portion and a lower second convex portion on an upper surface thereof,
In the cross section, the lower first concave portion is located between the lower first convex portion and the lower second convex portion,
In the cross section, the flat plate-like first electrode is located on the lower first convex portion, and in the cross section, the flat plate-like second electrode is located on the lower second convex portion. And
The first electrode group includes a first strip electrode,
The second electrode group includes a second strip electrode,
The first strip electrode is provided on at least one of a lower surface of the upper insulating substrate or an upper surface of the lower insulating substrate,
The second strip electrode is provided on at least one of the lower surface of the upper insulating substrate or the upper surface of the lower insulating substrate,
The first strip electrode is electrically connected to the flat plate-like first electrode and the flat plate-like third electrode,
The second strip electrode is electrically connected to the plate-like second electrode and the plate-like fourth electrode,
filter. 30. The filter of claim 29, comprising:
In the cross section, a lower second recess is provided on the upper surface of the lower insulating substrate,
In the cross section, a lower third convex portion is provided on the upper surface of the lower insulating substrate,
In the cross section, the lower second concave portion is located between the lower second convex portion and the lower third convex portion, and in the cross section, on the lower third convex portion, A plate-like third electrode is located,
filter. The filter according to claim 30, wherein
In the cross section, a lower third recess is provided on the upper surface of the lower insulating substrate,
In the cross section, a lower fourth convex portion is provided on the upper surface of the lower insulating substrate,
In the cross section, the lower third concave portion is located between the lower third convex portion and the lower fourth convex portion, and in the cross section, on the lower fourth convex portion, A flat fourth electrode is located,
filter. 30. The filter of claim 29, comprising:
In the cross section, an upper first recess is provided on a lower surface of the upper insulating substrate,
In the cross section, an upper first convex portion and an upper second convex portion are provided on the lower surface of the upper insulating substrate,
In the cross section, the upper first concave portion is located between the upper first convex portion and the upper second convex portion,
In the cross section, the upper first convex portion is located on the flat plate-like first electrode, and in the cross section, the upper second convex portion is located on the flat plate-like second electrode. ing,
filter. A filter according to claim 32, comprising:
In the cross section, an upper second concave portion is provided on the lower surface of the upper insulating substrate,
In the cross section, an upper third convex portion is provided on the lower surface of the upper insulating substrate,
In the cross section, the upper second concave portion is located between the upper second convex portion and the upper third convex portion, and in the cross section, the upper third convex portion is the flat plate-like third. Located on the electrode,
filter. 34. The filter of claim 33, wherein
In the cross section, an upper third recess is provided on the lower surface of the upper insulating substrate,
In the cross section, an upper fourth convex portion is provided on the lower surface of the upper insulating substrate,
In the cross section, the upper third concave portion is located between the upper third convex portion and the upper fourth convex portion, and in the cross section, the upper fourth convex portion is the flat plate-shaped fourth. Located on the electrode, 30. The filter of claim 29, comprising:
In the cross section, a lower first additional recess is provided on the upper surface of the lower insulating substrate,
And in the cross section, the lower first additional concave portion is located between the lower first convex portion and the lower second convex portion,
filter. 30. The filter of claim 29, comprising:
In another cross section including both the normal line of the flat plate-like first electrode and the normal line of the lower insulating substrate, the lower first concave portion does not appear.
filter. 30. The filter of claim 29, comprising:
The first strip electrode and the second strip electrode extend in a direction parallel to the normal line of the flat plate-like first electrode,
filter. 30. The filter of claim 29, comprising:
The lower first recess has a depth of 5 micrometers to 10 micrometers,
filter. 30. The filter of claim 29, comprising:
The first gap, the second gap, and the third gap all have a width of 10 micrometers to 35 micrometers. 30. The filter of claim 29, comprising:
Each of the flat plate-like first electrode to fourth electrode has a length of not less than 300 micrometers and not more than 10,000 micrometers.

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