JP4986504B2 - Electromagnetic flow measuring device - Google Patents

Description

  The present invention relates to an electromagnetic flow measurement device that measures the flow rate of a fluid to be measured, and more particularly to an electromagnetic flow measurement device that can measure a minute flow rate with high accuracy.

Conventionally, a magnetic field is generated perpendicular to the flow direction of the fluid to be measured, an electromotive force generated between a pair of detection electrodes arranged in contact with the fluid to be measured is detected, and the fluid to be measured is based on the detection signal. An electromagnetic flow rate measuring device that measures the flow rate of is known from Patent Document 1 below.
JP 2003-42821 A

  The sensing part of this type of electromagnetic flow measuring device is provided with a pair of detection electrodes in the vicinity of the inner wall surface in the flow path through which the fluid to be measured flows, so that the flow of the fluid to be measured is not obstructed. Although the flow rate of the liquid can be measured with high accuracy, the full scale of the minimum flow rate of the fluid to be measured that can be measured with high accuracy is about 0.3 m / sec.

  For this reason, when manufacturing a flow path for flowing a fluid to be measured at a small flow rate (for example, about 10 mL / min) when the full scale is 0.3 m / second, the flow path becomes extremely thin, and the detection electrode is attached. There was a problem that became difficult.

That is, for example, when measuring a fluid with a very small flow rate of about 10 mL / min, the inner diameter of the flow path through which the measured fluid passes is d (m), and a flow rate of 0.3 m / second is passed through the flow path. When flowing the fluid to be measured,
10 × 10 ⁻⁶ /60=3.14×(d/2) ² × 0.3
Therefore, the inner diameter d of the flow path is about 0.84 mm.

  Therefore, in the electromagnetic flow measuring device that measures the fluid to be measured with such a small flow rate, the flow path of the sensing unit that flows the fluid to be measured is a microtubule having an inner diameter of about 0.84 mm. It is necessary to attach an insulating lining in the microcapillary and to attach a pair of detection electrodes to the wall of the capillaries.

  However, in order to attach the detection electrode, a minute electrode hole is drilled in the wall surface of the micro-thin tube. However, even if a machine tool for precision machining is used, such a minute hole is accurately drilled. However, it is very difficult to attach the detection electrode while maintaining the tightness of the narrow tube, and it is difficult to manufacture the sensing part efficiently. For this reason, the electromagnetic flow measuring device for measuring a minute flow rate has a problem that mass production is difficult and the manufacturing cost increases.

  The present invention has been made in view of the above problems, and an object thereof is to provide an electromagnetic flow measuring device that can measure a minute flow rate of a fluid to be measured with high accuracy and can be mass-produced efficiently at a low cost. And

In order to achieve the above object, an electromagnetic flow measuring device of the present invention is in contact with an excitation device including an excitation coil that generates a magnetic field for a fluid to be measured flowing through a flow path, and the fluid to be measured in the flow path. a sensing unit having a sensing electrode pair disposed Te, based on a detection signal output from the detection electrode of the sensing unit, electromagnetic, comprising: a measurement processing circuit for calculating the flow rate of the fluid to be measured, the in the flow rate measuring device, 該被flow path of the fluid being measured is formed in the case, a channel chip forming the micro channel therein is provided in the sensing unit, a part of the flow channel member, the An insertion recess for inserting the flow channel chip of the sensing unit is formed, and the flow channel chip is fitted into the insertion recess in a watertight manner via a sealing material. The flow channel chip includes a silicon substrate and a glass substrate. , Glass substrates, silicon substrates, or Formed is superimposed a silicon substrate and the ceramic substrate, the detection electrodes of conductive material is attached formed on the inner wall of the fine narrow flow paths, the fine narrow flow paths of the flow path and the flow path within the chip flow channel member And an exciter for forming a magnetic field in a fine channel in the channel chip is disposed in the case .

  Here, the fine channel of the channel chip is formed on the silicon substrate using a masking process, a lithography process and an etching process, or formed on a glass substrate using a lithography process and a sandblasting process. be able to.

  Further, the detection electrode of the flow path chip can be formed on the silicon substrate or the glass substrate by using a lithography process, a thin film forming process, and an etching process.

  Further, the silicon substrate and glass substrate of the flow path chip, the glass substrates, the silicon substrates, or the silicon substrate and the ceramic substrate can be bonded by anodic bonding.

  The fine channel in the channel chip forms a groove having a closed shape on one silicon substrate or glass substrate and communicates with the other silicon substrate, glass substrate, or ceramic substrate. It can be formed by drilling a channel hole.

  Further, the fine channel in the channel chip can be formed by providing a groove having a shape with both ends opened on both side edges on one silicon substrate or glass substrate.

  The fine flow path in the flow path chip can be formed by providing a substantially U-shaped groove portion having both ends opened at one edge on one silicon substrate or glass substrate.

  In addition, a land portion is formed on the upper surface of one silicon substrate or glass substrate of the flow path chip using a lithography process and a thin film formation process, and the land portion is detected in the fine flow path via the conductive portion. It can be configured to be connected to an electrode.

  According to the electromagnetic flow rate measuring apparatus having the above configuration, the fine flow path is provided in the flow path chip formed by superposing the silicon substrate and the glass substrate, the silicon substrates, the glass substrates, or the silicon substrate and the ceramic substrate. In addition, since the sensing unit is configured to form a detection electrode by forming a conductive material on the inner wall of the fine channel, the fine channel is formed in a lithography process, an etching process, a silicon substrate or a glass substrate, Alternatively, it can be formed with high accuracy using a sandblasting process, and the detection electrode can be formed by a thin film forming process of a conductive material.

Therefore, it is possible to efficiently and easily manufacture a fine channel having a cross-sectional area of, for example, about 0.55 mm ² , and to efficiently and easily form a fine detection electrode in such a fine channel. It can be formed into a film. The electromagnetic flow measuring device having the sensing unit formed in this way can accurately measure a fluid to be measured with a minute flow velocity of about 0.3 m / second, for example.

  In addition, a fine flow path can be formed in a silicon substrate or a glass substrate with high accuracy by using a lithography process, an etching process, or a sand blast process, the variation in flow path dimension is reduced, and a thin film formation process of a conductive material is performed. Since a pair of detection electrodes can be formed with high accuracy, measurement errors due to asymmetry of the pair of electrodes and variations in measurement sensitivity for each product are reduced, and the accuracy of flow measurement of the fluid to be measured is improved. Can do.

  Furthermore, when forming a fine channel by a lithography / etching process, the change of the cross-sectional area of the channel can be easily performed by changing the depth of the channel by changing the etching time and by changing the photomask. Sensing units with different measurable flow ranges can be easily manufactured.

  Furthermore, since the detection electrode can be formed in the fine flow path of the flow path chip by a thin film forming process, the flow path chip can be manufactured at low cost and in large quantities. For this reason, the channel chip can be a disposable product. For example, when the electromagnetic flow measuring device is used for measuring a flow rate of an infusion solution (drip solution) or a dialysate in a medical device, the channel The sensing unit including can be used safely as a disposable instrument against infection and the like.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a perspective view of the electromagnetic flow measuring device with a cover removed from the case 1, FIG. 2 shows a II-II sectional view, and FIG. 3 shows a III-III enlarged sectional view. This electromagnetic flow measuring device generally includes an excitation device 30 including an excitation coil 32 that generates a magnetic field for a fluid to be measured flowing in the fine flow path 11a of the flow path chip 11 in the case 1, and a flow path. A sensing unit 10 provided with a pair of detection electrodes 16 and 18 in a microchannel 11a of a chip 11 and a circuit board 31 on which a measurement processing circuit for calculating the flow rate of a fluid to be measured is mounted. .

  The case 1 is formed in a substantially rectangular parallelepiped box shape, two surfaces are opened, and a cover plate (not shown) is put on the two opened surfaces and fixed. Or in the state which closed one opening part with the cover body, the inside of a case is molded and fixed with a filler. In the case 1, a pipe-shaped flow path body 2 is formed in the lateral direction, and both ends of the flow path body 2 are opened as connection ports 5 and 6. In addition, an insertion recess 4 is formed in a substantially central portion of the flow path body 2 in order to insert a flow path chip 11 of the sensing unit 10 and a core extension part 34a of the excitation device 30 described later. Wall portions are formed on both sides of the insertion recess 4, and communication holes 7 and 9 communicating with flow path holes 15 and 17 of a flow path chip 11 described below are formed downward in the lower wall portions on both sides. Has been. A plate-like chip recess 4a for inserting and fitting the flow channel chip 11 is formed below the insertion recess 4 in which the communication holes 7 and 9 are opened.

  The flow path chip 11 of the sensing unit 10 is made of a silicon wafer, a glass substrate, or the like, and a fine flow path 11a is formed in the silicon substrate 12 and the glass substrate 13 through a lithography process, an etching process, or a sandblast process. At the same time, the pair of detection electrodes 16 and 18 are formed in the fine flow path 11a by a thin film formation process, and the silicon substrate 12 and the glass substrate 13 are joined.

  When the flow path chip 11 is manufactured, first, the groove portion 14 is formed on the upper surface of each silicon substrate 12 on the silicon wafer as a material. As shown in FIG. 4, one silicon substrate 12 has a width of about 3 mm, a length of about 8 mm, and a depth of about 0.3 mm on a rectangular silicon substrate of about 0.5 mm thickness and about 10 mm square, for example. Usually, in the case of mass production, as shown in FIG. 6, a large number of silicon substrates 12 are formed on a silicon wafer having a thickness of about 0.5 mm, and finally they are cut. Will be used.

  The silicon wafer is first cleaned with an organic solvent or the like as a pretreatment to remove organic substances or oxide films on the surface of the wafer. Next, the cleaned silicon wafer is put into an oxidation furnace, and the silicon wafer is heat-treated in an oxidizing atmosphere at a temperature of about 1000 ° C. for a predetermined time to form an oxide film on the upper surface of the wafer. This oxide film is formed for masking and used as a protective film in a later etching process. Next, processing by a lithography method and an etching method is performed to form a groove portion 14 having a predetermined shape and a predetermined depth on each silicon substrate 12 on the silicon wafer.

  In the lithography process, first, a photoresist (photosensitive resin) is applied on the surface of the silicon wafer while the surface of the silicon wafer is heated and dried to improve adhesion. The coating is performed by spin coating, and a wafer with a photoresist is rotated at high speed to spread it.

  Next, pattern exposure is performed by irradiating the silicon wafer with ultraviolet rays by an exposure apparatus. In the case of a positive photoresist, the groove formed on the substrate is exposed and developed to dissolve and remove the exposed portion of the photoresist. Thereafter, the etching process is started.

  In the etching step, the silicon wafer is immersed in an etching solution (for example, hydrogen fluoride solution) for a predetermined time, etching is performed, and the surface of the silicon wafer is etched using the photoresist as a mask. Thereby, the surface (silicon oxide film) corresponding to the groove 14 on the silicon substrate is etched.

  Thereafter, the photoresist removal process is started, and the photoresist remaining on the silicon substrate 12 is removed by a stripping solution (alkaline organic solvent). Thereafter, the depth of the groove portion 14 is controlled by controlling the etching time in anisotropic etching. , Formed on the silicon substrate 12. As shown in FIG. 4, the groove 14 is formed in a state where both ends are closed.

  In the lithography method, the dimension of the groove 14 is determined with high accuracy by the exposure pattern of the exposure apparatus, and the dimensional accuracy can be within an error range of about 0.1 μm. Can be maintained with extremely high accuracy. Further, the depth of the groove portion 14 is controlled by the immersion treatment time at the time of etching. By determining the etching amount per unit time and controlling the immersion treatment time, the accuracy of the depth of the groove portion is about 1 μm. Error range. Therefore, for example, when the groove 14 having a width of 2.5 mm, a length of 8 mm, and a depth of 0.3 mm is formed on the silicon substrate 12, the groove 14 can be formed with high accuracy within an error range of 1 μm at the maximum. it can.

  Next, as described above, an oxide film is formed on the surface of the silicon substrate 12 with the grooves 14 formed on each silicon substrate 12 of the silicon wafer. This oxide film can be formed by heat treatment. The silicon wafer is put in an oxidation furnace, the silicon wafer is placed in an oxidizing atmosphere at a temperature of about 1000 ° C. for a predetermined time, and the surface of each silicon substrate 12 on the wafer is oxidized. A film is formed. At this time, the thickness of the oxide film formed on the surface determines the amount of oxide film formed per unit time and controls the oxidation time. Thereby, the thickness of the oxide film can be determined within an error range of about 0.1 μm. The interelectrode resistance necessary for the flow rate measurement is set to a predetermined value depending on the thickness of the oxide film formed with high accuracy.

  Next, a pair of detection electrodes 16 and 18 are formed in a thin film on the upper surface of each silicon substrate 12 of the silicon wafer on which an insulating oxide film is formed. As shown in FIG. 4, the pair of detection electrodes 16 and 18 are formed from the upper surface of each silicon substrate 12 to the side wall in the groove portion 14.

  When forming a thin film of the detection electrode, the silicon wafer having the silicon substrate 12 is washed with an organic solvent or the like as a pretreatment, and the organic substance on the surface of the substrate is removed and dried.

  Thereafter, a thin film forming process is started, and the silicon substrate 12 is put into, for example, a vacuum deposition apparatus, and an electrode material (for example, a conductive metal having good corrosion resistance such as Cr, Ni, Au, Pt) on the silicon substrate 12. Is vapor-deposited.

  Next, the upper surface of each silicon substrate 12 on the silicon wafer is processed by lithography and etching to form detection electrodes 16 and 18 having a predetermined shape. In the lithography process, as described above, a silicon wafer is heated and dried, and a photoresist is applied thereon by spin coating.

  Next, ultraviolet exposure is performed by an exposure apparatus to perform pattern exposure on each silicon substrate 12. In the case of a positive photoresist, the portions of the detection electrodes 16 and 18 formed on the substrate are not exposed, and development processing is performed to dissolve the exposed portion of the photoresist and expose unnecessary electrode materials. Thereafter, the etching process is started.

  In the etching step, the silicon substrate 12 is immersed in an etching solution for a predetermined time, etching is performed, and the electrode material on the silicon substrate is etched using the photoresist as a mask. Thereby, electrode materials other than the detection electrodes 16 and 18 on the silicon substrate 12 are removed by etching. Thereafter, the photoresist is removed with a stripping solution (alkali organic solvent) at about 90 ° C.

  Similarly to the above, since this lithography process uses a lithography etching method, the dimensions of the detection electrodes 16 and 18 are set with high accuracy by the exposure pattern by the exposure apparatus, and the dimensional accuracy is about 0.1 μm. Since the error range can be set, the position and dimensional accuracy of the detection electrodes 16 and 18 can be formed with extremely high accuracy. In the thin film formation step, the detection electrode can be formed by PVD such as sputtering or ion plating in addition to vacuum deposition.

  On the other hand, on the glass substrate 13 covered on the silicon substrate 12 so as to be a lid portion of the flow path chip 11, flow path holes 15 and 17 serving as entrances and exits of the fine flow path 11a are formed at predetermined positions by sandblasting. At the same time, the land portions 19 and 21 and the conductive portions 23 and 25 connected to the detection electrodes 16 and 18 are formed by a thin film forming technique.

  A glass substrate as a material is first washed with an organic solvent or the like as a pretreatment, and organic substances on the surface of the substrate are removed. Next, the cleaned material glass substrate is processed by a lithography method and a sand blast method to form channel holes 15 and 17 having a predetermined shape at predetermined positions on the upper surface of each glass substrate 13. Further, conductive holes (contact holes) are formed at positions corresponding to the detection electrodes 16 and 18 of the silicon substrate 12. In the lithography process, first, a material glass substrate is heated and dried to improve adhesion, and a photoresist is applied thereon by spin coating.

  Next, pattern exposure is performed by irradiating the photoresist on the material glass substrate with ultraviolet rays by an exposure apparatus. In the case of a positive photoresist, the channel hole and the conductive hole formed on the substrate are exposed, and development processing is performed to dissolve and remove the photoresist in the exposed portion. Thereafter, the sandblasting process is started.

  In the sand blasting process, sand is sprayed on the surface of each glass substrate 13 of the material glass substrate, and the surface of each glass substrate 13 is blasted using a photoresist as a mask. By this blasting process, conductive holes are formed on the glass substrates 13 at the positions of the flow path holes 15 and 17 and the land portions.

  Next, a pair of land portions 19 and 21 and conductive portions 23 and 25 are formed in a thin film on each glass substrate 13 of the material glass substrate. The land portions 19 and 21 and the conductive portions 23 and 25 connected to the bottom thereof can be integrally formed by a single vacuum deposition.

  When the land portions 19 and 21 and the conductive portions 23 and 25 are formed into a thin film, the glass substrate 13 is washed with an organic solvent or the like as a pretreatment to remove organic substances on the surface of the substrate. In the thin film forming step, the glass substrate 13 is placed in a vacuum vapor deposition apparatus, and a conductive metal (for example, Au) is vapor-deposited on the glass substrate 13 over the entire surface.

  Next, the glass substrate 13 is processed by a lithography method and an etching method to form land portions 19 and 21 and conductive portions 23 and 25 having a predetermined shape on the upper surface of the glass substrate 13. In the lithography process, as described above, a photoresist is applied onto the material glass substrate in a state where the material glass substrate is heated and dried to improve the adhesion.

  Next, pattern exposure is performed by irradiating ultraviolet rays onto each glass substrate 13 of the material glass substrate by an exposure apparatus. In the case of a positive photoresist, the portions other than the land portions 19 and 21 formed on the substrate are exposed and developed to dissolve and remove the photoresist at the exposed portions, which is unnecessary for the land portion formation. Expose conductive metal. Thereafter, the etching process is started.

  In the etching step, the glass substrate 13 is immersed in an etching solution for a predetermined time, an etching process is performed, and the conductive metal on the glass substrate is etched using the photoresist as a mask. Thereby, conductive metals other than the land portions 19 and 21 and the conductive portions 23 and 25 on the glass substrate 13 are removed by etching. Thereafter, the photoresist is removed by a stripping solution heated to about 90 ° C.

  The silicon substrate 12 and the glass substrate 13 manufactured as described above are thereafter anodic bonded in a state where the glass substrate 13 is accurately superimposed on the silicon substrate 12 as shown in FIGS. It is applied to the apparatus, and the bonding surface between the glass substrate 13 and the silicon substrate 12 is anodically bonded. It should be noted that the oxide film or the like on the bonding surface of the silicon substrate 12 is anodic bonded in a removed state.

  After that, by burying conductive resin or the like in the conductive portions 23 and 25 of the glass substrate 13, the detection electrodes 16 and 18 of the silicon substrate 12 and the land portions 19 and 21 of the glass substrate 13 are electrically connected. At this time, the detection electrodes 16 and 18 and the land portions 19 and 21 can be electrically connected by a thin film forming process instead of the conductive resin or the like. Then, it is applied to a cutting device, cut into each part, and separated.

  The anodic bonding of the glass substrate 13 and the silicon substrate 12 is performed by applying a negative voltage of about 500 V to the glass substrate side under heating at about 300 to 400 ° C., and the glass substrate 13 and the silicon substrate 12 are in a solid state. By generating an electric double layer, a strong electrostatic attractive force is generated between the two substrates and chemically bonded at the interface. For this reason, the glass substrate 13 and the silicon substrate 12 are bonded with high dimensional accuracy with almost no dimensional change.

As described above, in the flow path chip 11 in which the silicon substrate 12 and the glass substrate 13 are joined, the flow path holes 15 and 17 and the groove portion 14 communicate with each other as shown in FIG. A fine channel 11a is formed. As described above, the fine channel 11a is formed with, for example, a width of 2.75 mm, a length of 8 mm, and a depth of 0.2 mm, and the cross-sectional area of the channel is about 0.55 mm ² . A minute flow rate of a fluid to be measured having a flow rate of about 10 mL / min and a flow rate of about 0.3 m / sec can be flowed through the fine channel 11a, and the flow rate can be measured.

  The channel chip 11 configured as described above has the lead wire 36 soldered to the land portions 19 and 21 on the upper surface thereof, and the chip of the channel body 2 in the case 1 as shown in FIGS. It fits in the recessed part 4a for water through a sealing material in a watertight state. In this state, the communication hole 7 on the flow channel body 2 side is attached to the flow channel hole 15 of the flow channel chip 11, and the communication hole 9 is connected to the flow channel hole 17 of the flow channel chip 11 with accurate communication connection.

  On the other hand, as shown in FIGS. 8 and 9, the excitation device 30 is configured to be housed in the upper part of the flow path body 2 in the case 1, and the circuit board 31 is mounted on the upper part of the rectangular mounting frame 35. A bobbin 33 around which the exciting coil 32 is wound is attached to the lower part of the attachment frame 35. The core 34 is inserted into the axial center position of the bobbin 33, the substantially L-shaped core extending portions 34a and 34b protrude laterally from both ends of the core 34, and the leading ends of the core extending portions 34a and 34b have slits. It arrange | positions so that it may oppose.

  The flow path chip 11 is mounted so that the fine flow path 11a of the flow path chip 11 is located between the distal ends of the core extending portions 34a and 34b, that is, in the slit. Thereby, the front-end | tip part of core extension part 34a, 34b will be located facing the upper part and the lower part of the microchannel 11a. The gap between the tips of the core extending portions 34a and 34b, that is, the slit that becomes the magnetic gap is formed to be as small as possible so that the magnetic resistance at that portion is minimized.

  Further, the core extending portion 34a located in the upper part of FIG. 3 has a two-layer structure with a space in between for passing the lead wire 36, for example, two metal plates are located in the lower part of FIG. It has a structure in which it is fixed by being overlapped on both sides of the core extending portion 34b. As described above, the core extending portion 34a has a two-layer structure and the core extending portion 34b has a one-layer structure, so that the number of processing steps can be reduced and a magnetic circuit can be manufactured at low cost.

  The lead wire 36 connected to the land portions 19 and 21 of the flow path chip 11 passes through the internal space of the core extension portion 34a of the excitation device 30 and is input to the input side of the flow rate measurement processing circuit mounted on the circuit board 31. Connected. In the excitation device 30, excitation is performed so that the magnetic field generated by the excitation coil 32 is generated in the direction perpendicular to the flow direction of the microchannel 11a at the tip of the core extension 34a.

  If the lead wire 36 is detachably connected to the input terminal of the measurement processing circuit, the flow path body 2 including the case 1 and the flow path chip 11 are removed by removing the excitation device 30 from the case 1 after use. As a disposable instrument, can be safely used for medical devices and the like, as will be described later.

  The measurement processing circuit is an excitation power supply circuit that supplies an alternating current (rectangular current) of, for example, about 30 Hz to the excitation coil 32. The lead wire 36 is connected to the input side, and the electromotive force generated between the detection electrodes 16 and 18 is generated. Based on an amplifier that amplifies and outputs a detection signal, samples the detection signal from the amplifier at a predetermined timing, converts the sampled voltage value into a digital value, and measurement data converted into a digital value, It is composed of a circuit such as an arithmetic processing circuit for calculating the flow rate of the fluid to be measured.

  The electromagnetic flow rate measuring device configured as described above is used for measuring the flow rate of a fluid to be measured with a small flow rate, such as an infusion solution (drip solution) in the medical field, a dialysate, or a chemical solution in the agricultural field. The connection ports 5 and 6 provided in the are connected to a tube or the like serving as a flow path for flowing the fluid to be measured at a minute flow rate. The fluid to be measured enters the flow path body 2 in the case 1 from the connection port 5 or 6, and passes from the communication hole 7 or 9 of the flow path body 2 to the flow path hole 15 or 17 of the flow path chip 11 of the sensing unit 10. It flows in and flows through the fine channel 11a.

  In this state, the measurement processing circuit and the excitation device 30 on the circuit board 31 are operated, and an alternating current (rectangular current) of about 30 Hz is supplied to the excitation coil 32 from the excitation power supply circuit. A magnetic field is generated vertically. At this time, when a conductive fluid to be measured flows through the fine channel 11a, an electromotive force corresponding to the flow rate is generated between the detection electrodes 16 and 18, and the electromotive force is used as a detection signal for flow rate measurement processing circuit. Is taken in. In the measurement processing circuit, after the detection signal is amplified by the amplifier, sampling is performed at a predetermined timing, the voltage value is converted into a digital value, and the flow rate of the fluid to be measured is based on the measurement data converted into the digital value. Is calculated.

  As described above, the sensing unit 10 of the electromagnetic flow measuring device is provided with the fine flow passage 11a in the flow passage chip 11 formed of the silicon substrate 12 and the glass substrate 13, and is electrically conductive on the inner wall of the fine flow passage 11a. Since the detection electrodes 16 and 18 are formed by forming a conductive material, the fine flow path 11a is finely formed in the silicon substrate 12 and the glass substrate 13 by using a lithography process, an etching process, or a sandblasting process. The flow path can be formed with high accuracy, and the detection electrodes 16 and 18 can be formed by a thin film forming process of a conductive material.

Therefore, a micro flow channel having a cross-sectional area of, for example, about 0.55 mm ² can be efficiently and easily manufactured in the flow channel chip 11 with high accuracy, and fine detection in such a micro flow channel is possible. The electrode can be formed efficiently and easily. Therefore, the electromagnetic flow rate measuring device provided with the sensing unit 10 having such a flow path chip 11 can measure a fluid to be measured with a minute flow rate of about 0.3 m / second.

  Further, a fine flow path can be formed in the silicon substrate 12 using a lithography process or an etching process, or a fine flow path can be formed in the glass substrate 13 using a sand blast process, and a conductive material can be formed. Since the pair of detection electrodes 16 and 18 can be formed in the fine flow path with high accuracy by the thin film formation process, measurement errors due to asymmetry of the pair of detection electrodes and variations in measurement accuracy for each product are reduced. The flow rate of the fluid to be measured can be accurately measured.

  Further, when the fine channel 11a is formed by a lithography / etching process, the cross-sectional area of the fine channel 11a can be easily changed by changing the etching time or changing the photomask. It is possible to easily manufacture the flow path chip 11 of the different sensing units 10. Further, by simply exchanging the flow channel chip 11, parts other than the flow channel chip 11 can be used as they are, and a flow meter having a different flow rate range can be easily manufactured.

  Furthermore, the sensing unit 10 of the electromagnetic flow measuring device in which the detection electrodes 16 and 18 are formed in a thin film on the channel chip 11 is very small, low cost, and can be mass-produced. Can do. For example, when this electromagnetic flow measuring device is used for measuring the flow rate of an infusion solution (drip solution) or dialysate in a medical device, the sensing unit 10 including the fine channel 11a is separated from the excitation device 30 and is disposable. Use as an instrument. This makes it possible to provide a flow rate measuring device that is safe against infection and the like.

  10-12 has shown the flow-path chip | tip 41 of other embodiment. As shown in FIG. 10, the flow path chip 41 is configured by stacking and bonding a glass substrate 43 on a silicon substrate 42 in the same manner as described above, but a groove formed on the upper surface of the silicon substrate 42. 44 is formed with both ends opened as it is at both side edges of the substrate, and the glass substrate 43 is not provided with the above-described flow path holes. The groove 44 on the silicon substrate 42 is formed with high accuracy using a lithography process and an etching process, as described above.

  Then, a pair of detection electrodes 46 and 48 are formed on both sides of the silicon substrate 42 from the upper surface to the groove portion 44 by using, for example, vacuum evaporation to form a conductive material such as Au. Similarly to the above, a conductive hole is formed on the glass substrate 43 by sandblasting at the land portion, and then, for example, by vacuum deposition in a thin film forming process, from the conductive hole of the glass substrate 43 to the land portion region, Au or the like. A conductive material is formed into a film, and land portions 49 and 51 and subsequent conductive portions are formed.

  Thereafter, as shown in FIG. 11, the silicon substrate 42 and the glass substrate 43 are put on an anodic bonding apparatus in a state where the glass substrate 43 is accurately superimposed on the silicon substrate 42 as described above. The bonding surface of the silicon substrate 42 is anodically bonded. Thereafter, a conductive resin is embedded in the conductive holes of the glass substrate 43 to electrically connect the electrodes 46 and 48 of the silicon substrate 42 and the land portions 49 and 51 of the glass substrate 43. Alternatively, they are electrically connected by a thin film forming process. Thus, the glass substrate 43 and the silicon substrate 42 are joined to form the flow channel chip 41, and the upper surface of the groove 44 is covered with the glass substrate 43, and the fine flow channel 41a is formed there. As shown in FIG. 11, the fine channel 41a of the channel chip 41 has a shape in which an end thereof is opened on both side surfaces.

  On the other hand, the flow channel body 52 to which the flow channel chip 41 is mounted is formed separately from the center portion on the left and right sides, as shown in FIG. Formed in the direction. The insertion recess and the flow path 53 in the flow path body 52 are connected in communication through the communication holes 57 and 59. As shown in FIG. 12, the channel chip 41 is fitted in the insertion recesses at the tip portions of the left and right channel bodies 52 in a watertight state via a sealing material. In this state, the communication hole 57 of the channel body 52 is inserted. , 59 are connected in communication with a fine channel 41a formed in the channel chip 41.

  Although not shown, even in the flow channel body 52 to which the flow channel chip 41 is mounted, the excitation device having the same configuration as described above is configured so that the fine flow channel 41a of the flow channel chip 41 is provided in the front end slit of the core front end portion. It is mounted so as to be sandwiched from above and below. Further, the lead wires connected to the land portions 49 and 51 on the flow path chip 41 are connected to the input side of the measurement processing circuit mounted on the circuit board of the excitation device, as described above.

  Thus, even the flow channel chip 41 having both ends opened to form the fine flow channel 41a and the detection electrodes 46 and 48 formed on the inside thereof is fitted into the insertion recess of the flow channel body 52. And can be used in a flow rate measuring device.

  FIG. 13 shows another embodiment of the core 34A constituting the excitation device 30A. The core 34A is formed in a substantially E shape, and an exciting coil 32A is wound around the center of the core 34A. In the exciting device 30A, the magnetic field lines generated between the central portion and the outer peripheral portion of the core 34A are generated so as to cross the center of the flow channel chip 41 and excited. The excitation device 30A having such a core 34A can be used by being attached to the upper side or the lower side of the flow channel chip 41, and the structure in which the excitation device 30A is mounted from the same direction as the insertion direction of the flow channel chip 41. Then, the opening of the case of the flow rate measuring device can be provided only at one place, and the excitation device 30A can be easily attached.

  14 and 15 show a flow channel chip 61 of still another embodiment. As shown in FIG. 14, the flow path chip 61 is configured by superposing and bonding a glass substrate 63 on a silicon substrate 62 in the same manner as described above. Here, the width of the glass substrate 63 superimposed on the silicon substrate 62 is formed shorter than the width of the silicon substrate 62. Further, the groove 64 formed on the upper surface of the silicon substrate 62 is formed with both ends opened as they are at both side edges of the substrate. The groove portion 64 on the silicon substrate 62 is formed with high accuracy using a lithography process and an etching process, as described above.

  Further, a pair of detection electrodes 66 and 68 are formed on both sides of the silicon substrate 62 from the upper surface to the groove portion 64 by, for example, vacuum deposition using Au or the like in a thin film forming process. When the detection electrodes 66 and 68 are formed and formed of Au, after Cr is formed as a base, Au is formed thereon. On the other hand, no land portion is formed on the glass substrate 63, and the glass substrate 63 can be used as it is without being processed.

  Thereafter, as shown in FIG. 15, the silicon substrate 62 and the glass substrate 63 are put on an anodic bonding apparatus in a state where the glass substrate 63 is accurately superimposed on the silicon substrate 62 as described above, and the glass substrate The joining surface of 63 and the silicon substrate 62 is anodically joined. The flow path chip 61 formed by anodically bonding the bonding surfaces of the glass substrate 63 and the silicon substrate 62 has a width of the glass substrate 63 shorter than the width of the silicon substrate 62 as shown in FIG. The electrodes 66 and 68 are exposed from both sides.

  Therefore, the lead wire for taking out the detection signal is directly soldered and connected to the exposed portions of the detection electrodes 66 and 68. By adopting such a configuration, the lead wire is directly soldered to the exposed portions of the detection electrodes 66 and 68, so that the step of forming the land portion on the glass substrate 63 is not required, and the flow can be reduced with fewer steps. The road chip 61 can be manufactured.

  The flow path body to which the flow path chip 61 is mounted is formed separately from the center portion on the left and right sides as described above, and the insertion recesses are formed in the axial direction at the tip portions of the left and right flow path bodies. And the flow channel in the flow channel body are connected in communication through the communication hole. Similarly to the above, the channel chip 61 is fitted in the insertion recesses at the tip portions of the left and right channel bodies in a watertight state via a sealing material, and the communication hole of the channel body is formed in the channel chip 61. It will be connected in communication with the formed fine channel.

  FIG. 16 shows a channel chip 71 according to still another embodiment. As shown in FIG. 16, the flow path chip 71 is configured by superposing and bonding a glass substrate 73 on a silicon substrate 72, and the groove portion 74 formed on the upper surface of the silicon substrate 72 has a substantially rectangular shape. It is formed in a letter shape, and both ends of the groove 74 are formed to open at the edge of the substrate. The groove 74 on the silicon substrate 72 is formed with high accuracy using a lithography process and an etching process, as described above.

  Then, a pair of detection electrodes 76 and 78 are formed on both sides from the upper surface of the silicon substrate 72 to the central portion of the groove portion 74 in a thin film forming process using, for example, vacuum evaporation and the like with a conductive material such as Au. Is done. Similarly to the above, a conductive hole is formed in the glass substrate 73 at the land portion by sandblasting, and then, for example, by vacuum deposition in a thin film formation process, Au or the like is formed from the conductive hole of the glass substrate 73 to the land portion region. A conductive material is formed into a film, and land portions 79 and 81 and subsequent conductive portions are formed.

  Thereafter, the silicon substrate 72 and the glass substrate 73 are applied to an anodic bonding apparatus in a state where the glass substrate 73 is accurately superimposed on the silicon substrate 72, and the bonding surfaces of the glass substrate 73 and the silicon substrate 72 are anodically bonded. The Thereafter, the detection electrodes 76 and 78 of the silicon substrate 72 and the land portions 79 and 81 of the glass substrate 73 are electrically connected by a conductive resin or the like. Thus, the glass substrate 73 and the silicon substrate 72 are joined to form the flow channel chip 71, and the upper surface of the groove 74 is covered with the glass substrate 73, and a fine flow channel is formed there. The fine channel of the channel chip 71 has a shape in which the end portions on both sides thereof are open to one edge of the channel chip 71. Such a channel chip 71 is assembled in a channel body (not shown), and a communication port of the channel in the channel body is connected to an opening end of a fine channel opened at an edge of the channel chip 71. The

  In the embodiment shown in FIG. 4, only the detection electrodes 16 and 18 are formed in the groove 14. However, as shown in FIG. 17, a pair of ground electrodes is provided on both sides of the groove 14 together with the detection electrodes 16 and 18. 20a and 20b can also be formed.

  In the above embodiment, the groove portion is formed in the silicon substrate, the detection electrode is formed in the groove portion, and the flow path chip is bonded by anodic bonding so that the glass substrate is covered on the silicon substrate. In addition to forming a groove in the silicon substrate, a detection electrode is formed in the groove, a silicon substrate with an insulating film on the surface and the electrode hole is covered on the silicon substrate, and a glass thin film is applied to the bonding portion. It is also possible to form a channel chip by anodic bonding or fusion welding. Further, the channel chip can be formed using a ceramic substrate instead of the glass substrate. Further, a groove is formed on the glass substrate, and a detection electrode is formed in the groove, and the glass substrate is placed on the glass substrate and fused or bonded. Alternatively, a flow path chip can be formed by forming a thin film of silicon or aluminum and anodically bonding the glasses through the thin film.

1 is a perspective view of an electromagnetic flow measuring device according to an embodiment of the present invention, with a cover removed from a case. It is II-II sectional drawing of FIG. FIG. 3 is an enlarged sectional view taken along line III-III in FIG. 1. It is a disassembled perspective view of a silicon substrate and a glass substrate. It is a perspective view of a channel chip formed by bonding a silicon substrate and a glass substrate. It is a perspective view of the silicon substrate formed on the silicon wafer. It is a schematic diagrammatic expanded sectional view of a channel chip. It is a disassembled perspective view from the lower part of the state which mounts an exciting device and a flow-path chip | tip in a case. It is a disassembled perspective view of the state which mounts an exciting device and a flow-path chip | tip in a case. It is a disassembled perspective view of the silicon substrate and glass substrate of other embodiment. It is a disassembled perspective view of the flow-path chip | tip which joined the silicon substrate and the glass substrate. It is an expanded sectional view of the state where the channel chip was attached to the channel body. It is an expanded sectional view of the state where the exciter was attached to the same channel object. It is a disassembled perspective view of the silicon substrate and glass substrate of other embodiment. It is a schematic diagrammatic expanded sectional view of the channel chip. It is a disassembled perspective view of the silicon substrate and glass substrate of another embodiment. It is a disassembled perspective view of the silicon substrate and glass substrate of another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Case 2 Channel body 10 Sensing part 11 Channel chip 11a Fine channel 12 Silicon substrate 13 Glass substrate 14 Groove part 15, 17 Channel hole 16, 18 Detection electrode 19, 21 Land part 30 Excitation apparatus 31 Circuit board 32 Excitation coil

Claims (8)

An excitation device including an excitation coil that generates a magnetic field for a fluid to be measured flowing through a flow path;
A sensing unit having a pair of detection electrodes disposed in contact with the fluid to be measured in the flow path;
A measurement processing circuit that calculates a flow rate of the fluid to be measured based on a detection signal output from the detection electrode of the sensing unit;
In an electromagnetic flow measuring device equipped with
A flow channel body of the fluid to be measured is formed in the case, and the sensing unit is provided with a flow channel chip in which a fine flow channel is formed,
An insertion recess for inserting the flow path chip of the sensing unit is formed in a part of the flow path body, and the flow path chip is fitted into the insertion recess in a watertight manner via a sealant,
The flow path chip is formed by overlapping a silicon substrate and a glass substrate, glass substrates, silicon substrates, or a silicon substrate and a ceramic substrate,
A detection electrode made of a conductive material is attached to the inner wall of the fine channel,
The flow path of the flow path body and the fine flow path in the flow path chip are connected in communication,
An electromagnetic flow rate measuring device, wherein an excitation device for forming a magnetic field in the fine flow channel in the flow channel chip is disposed in the case.   The fine flow path of the flow path chip is formed on the silicon substrate using a masking process, a lithography process, and an etching process, or formed on a glass substrate using a lithography process and a sandblasting process. The electromagnetic flow measuring device according to claim 1, wherein   2. The electromagnetic flow measurement according to claim 1, wherein the detection electrode of the flow path chip is formed on the silicon substrate or the glass substrate by using a lithography process, a thin film forming process, and an etching process. apparatus.   2. The electromagnetic flow rate measuring apparatus according to claim 1, wherein the silicon substrate and the glass substrate, the glass substrates, the silicon substrates, or the silicon substrate and the ceramic substrate of the flow path chip are bonded by anodic bonding.   The fine flow channel in the flow channel chip forms a groove having a closed shape on one silicon substrate or glass substrate and communicates with the groove on the other silicon substrate, glass substrate, or ceramic substrate. 3. The electromagnetic flow measuring device according to claim 2, wherein the electromagnetic flow measuring device is formed by forming a hole.   3. The electromagnetic flow rate measurement according to claim 2, wherein the fine flow path in the flow path chip is formed by providing a groove portion having a shape in which both ends are opened at both side edges on one silicon substrate or glass substrate. apparatus.   The fine flow path in the flow path chip is formed by providing a substantially U-shaped groove portion having both ends opened at one edge on one silicon substrate or glass substrate. Electromagnetic flow measuring device.   A land portion is formed on the upper surface of one silicon substrate or glass substrate of the flow path chip using a lithography process and a thin film forming process, and the land section is formed on the detection electrode in the fine flow path via the conductive section. The electromagnetic flow measuring device according to claim 2 or 3, wherein the electromagnetic flow measuring device is connected.

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