WO2021053896A1

WO2021053896A1 - Filter, filter unit, and filter device

Info

Publication number: WO2021053896A1
Application number: PCT/JP2020/022478
Authority: WO
Inventors: 洋昌佐伯
Original assignee: 株式会社村田製作所
Priority date: 2019-09-20
Filing date: 2020-06-08
Publication date: 2021-03-25

Abstract

Provided are a filter that collects or separates a target substance, a filter unit, and a filter device. The filter comprises an electric conductor capable of circulating a liquid, an insulator film that covers a portion of the electric conductor that the liquid comes into contact with, and a voltage application unit for applying voltage from the exterior, the voltage application unit being positioned in a portion of the surface of the electric conductor that the liquid does not come into contact with.

Description

Filters, filter units, and filter devices

The present invention relates to a filter that collects or separates.

In recent years, as a method of diagnosing a disease, a method of collecting and inspecting a specific substance as a biomarker from a body fluid or the like has been disclosed. For example, Non-Patent Document 1 discloses a method for collecting exosomes in urine by utilizing a fixed charge on the surface of a substance. In the invention described in Non-Patent Document 1, urine is passed through zinc oxide nanowires fixed to a microfluidic substrate to collect exosomes in urine to a fixed charge of the nanowires.

In the invention described in Non-Patent Document 1, since the surface charge of the nanowire is fixed, the nanowire cannot release the captured exosome itself. Conventional techniques cannot capture or release target substances.

Therefore, an object of the present invention is to provide a filter, a filter unit, and a filter device for collecting or separating a target substance.

The filter of the present invention is located on a conductor capable of flowing a liquid, an insulator film covering a portion of the conductor that the liquid contacts, and a portion of the surface of the conductor that the liquid does not contact. It is characterized by including a voltage application unit for applying a voltage from the outside.

In this configuration, the insulator film adsorbs the target substance in the liquid by the applied voltage. Since the part of the filter in contact with the liquid is covered with an insulator, no current flows due to the voltage. Since the insulator film adsorbs the substance by the voltage, the adsorption of the substance by the voltage can be released by stopping the application of the voltage. This allows the filter to collect or separate the target material.

According to the present invention, the target substance can be collected or separated.

FIG. 1A is a schematic view showing the configuration of the filter device 100 according to the embodiment. FIG. 1B is a schematic cross-sectional view of the filter unit 101. FIG. 2A is a schematic perspective view showing the filter 20, and FIG. 2B is a partially enlarged cross-sectional view of the filter 20. FIG. 3 is a diagram for explaining one usage state of the filter 20. 4 (A) to 4 (C) are diagrams for explaining a method for inspecting bacteria using the filter device 100. 5 (A) to 5 (C) are diagrams for explaining medium exchange using the filter device 100. FIG. 6 is a graph showing the results of Example 1. FIG. 7 is a graph showing the results of Example 2.

FIG. 1A is a schematic view showing the configuration of the filter device 100 according to the embodiment. FIG. 1B is a schematic cross-sectional view of the filter unit 101. In FIG. 1A, the filter 20 is represented by a broken line. Hereinafter, the axial direction of the filter unit 101 will be described as the Z direction.

As shown in FIG. 1A, the filter device 100 according to the present embodiment includes a filter unit 101, a DC power supply 102, and a control unit 103. Further, the filter device 100 includes a pump (not shown).

The filter unit 101 is connected to the DC power supply 102. A DC voltage is applied to the filter unit 101 from the DC power supply 102. The DC power supply 102 is connected to the control unit 103. The control unit 103 controls the DC voltage of the DC power supply 102. For example, the control unit 103 switches the DC voltage of the DC power supply 102 between positive and negative. As a result, the user can control the DC voltage applied to the filter unit 101 via the control unit 103.

As shown in FIG. 1 (B), the filter unit 101 includes a filter 20 and a fixture 10. The fixture 10 fixes the filter 20. The shape of the filter unit 101 is substantially tubular and has an internal space 13. The filter 20 is arranged at the central portion of the filter unit 101 in the axial direction.

The fixture 10 includes two joints 11 and a socket 12. The joint 11 and the socket 12 are tubular and have both ends open. The joint 11 constitutes the internal space 13. The two joints 11 are arranged so as to sandwich the filter 20 and their internal spaces 13 are continuous. The socket 12 is arranged on the side surface of the two joints 11 and the filter 20 so as to cover the periphery of the two joints 11 and the filter 20. As a result, as shown by the arrow shown in FIG. 1 (B), when the liquid is made to flow into one internal space 13 by a pump (not shown), the liquid flows out from the other internal space 13 through the filter 20. The joint 11 is an example of the side wall portion of the flow path in the present invention.

FIG. 2A is a schematic perspective view showing the filter 20. FIG. 2B is a partially enlarged cross-sectional view of the filter 20. Note that FIG. 2B is a view in which a part of the distribution section 21 is cut along a plane parallel to the Z direction.

As shown in FIG. 2A, the filter 20 includes a distribution unit 21, a frame unit 22, and a voltage application unit 16. The frame portion 22 is formed so as to surround the circulation portion 21. The frame portion 22 is a portion sandwiched by the joints 11, and the distribution portion 21 is a portion arranged in the internal space 13.

The distribution unit 21 has a mesh structure. The distribution unit 21 is formed by arranging linear conductors 23 made of metal in a mesh pattern. The distribution section 21 and the frame section 22 may be integrally formed of the same material of the conductor 23. As the conductor 23, for example, stainless steel, iron, copper, aluminum, silver and the like can be used. As shown in FIG. 2B, a flow path 25 capable of flowing a liquid is formed between the plurality of conductors 23. The filter 20 can circulate the liquid through the flow path 25.

The conductor 23 is covered with an insulator film 24. The insulator film 24 covers at least a portion of the conductor 23 that comes into contact with the liquid. In other words, the insulator film 24 covers the distribution section 21 arranged in the flow path 25. Therefore, even if a voltage is applied to the conductor 23, no current flows. In the present embodiment, the flow section 21 is at least a portion of the conductor 23 that comes into contact with the liquid, and is an example of the liquid passage section in the present invention.

The insulator film 24 is preferably formed by an atomic layer deposition method, that is, an ALD (Atomic layer deposition) method. In the ALD method, even a surface having a complicated shape can be uniformly covered. Therefore, even the conductor 23 having a mesh structure can be uniformly coated. The insulator film 24 may be coated by a method other than the ALD method. For example, the insulator film 24 may be formed by anodization treatment.

The insulator film 24 is, for example, titanium (TiO ₂ ), alumina (Al ₂ O ₃ ), silica (SiO ₂ ), hafnia (HfO), zirconia (ZrO ₂ ), zinc oxide (ZnO), or nickel oxide (NiO). Is preferably contained, and in particular, titania is preferably contained. Since titania is a material having excellent biocompatibility, it reduces the influence on the biological sample. Since silica is a substance that is easily negatively charged, it is difficult for a substance having a negative charge to be adsorbed when a positive voltage is not applied to the conductor 23. Therefore, when silica is used for the insulator film 24, the filter 20 can easily prevent clogging of a substance having a negative charge. Since zinc oxide, nickel oxide, and zirconia are substances that are easily charged positively, they are likely to adsorb substances that have a negative charge on the conductor 23 to which a positive voltage is applied. Further, since the isoelectric point of alumina and titania is near the neutral point, the surface charge in the neutral region is close to zero. Therefore, the user applies a positive voltage to the conductor 23 to adsorb a substance having a negative charge, or applies a negative voltage to the conductor 23 to adsorb a substance having a positive charge. It is easy to use regardless of whether the target substance is positively or negatively charged.

The voltage application unit 16 is located on the surface of the conductor 23 where the liquid does not come into contact. The voltage application unit 16 is located, for example, on the side surface of the filter 20, that is, the side surface of the frame unit 22. Further, the voltage application unit 16 can be formed by forming an insulator film 24 on the entire conductor 23 by the ALD method and then scraping off a part of the insulator film 24. By scraping off the insulator film 24, the conductor 23 is exposed on the surface. As a result, the filter 20 forms a portion that is electrically connected to the outside. Of course, when the insulator film 24 is formed, the voltage applying portion 16 may be formed by patterning so that only the portion that becomes the voltage applying portion 16 is not formed.

The voltage application unit 16 comes into contact with the socket 12. The voltage application unit 16 can be electrically connected to the external DC power supply 102 via the socket 12. As a result, the voltage application unit 16 can apply a voltage to the conductor 23 from the outside via the socket 12. The voltage application unit 16 may be electrically connected to the external DC power supply 102 via any location of the fixture 10.

In the filter unit 101, the filter 20 may have a structure having a diameter larger than that of the two joints 11. The filter 20 is arranged so as to be sandwiched between the two joints 11, and the outer peripheral portion is exposed to the outside. In this case, the voltage application unit 16 formed on the side surface of the filter 20 can be directly connected to the DC power supply 102. Therefore, since the socket 12 is not required, the configuration of the filter unit 101 can be simplified.

Next, how to use the filter device 100 will be described. FIG. 3 is a diagram for explaining one usage state of the filter 20. The user first applies a positive voltage from the DC power supply 102 to the filter 20 via the control unit 103. As a result, a positive voltage is applied to the conductor 23 of the circulation unit 21. As shown in FIG. 3, a liquid containing the negatively charged substance 30 is flowed through the filter 20 along the direction of the arrow. At this time, since a positive voltage is applied to the conductor 23, the substance 30 is attracted to and adsorbed on the surface of the insulator film 24. Here, if the application of the positive voltage to the conductor 23 is stopped, the force for attracting the substance 30 on the surface of the insulator film 24 is weakened. As a result, the insulator film 24 can release the adsorption of the substance 30.

Further, at this time, the user can also apply a negative voltage from the DC power supply 102 to the filter 20 via the control unit 103. In this case, the insulator film 24 generates a repulsive force with the substance 30 adsorbed by the applied negative voltage. Therefore, the insulator film 24 can positively desorb the substance 30. In this way, the filter 20 can collect or separate the negatively charged substance 30 which is the target substance. The target substance 30, for example, includes bacteria, viruses, fungi, cells, DNA, RNA, extracellular vesicles, blood cells, some proteins, microbeads, and the like.

The user can also first apply a negative voltage from the DC power supply 102 to the filter 20 via the control unit 103. In this case, the insulator film 24 can collect or separate a substance having a positive charge as a target substance.

Here, in the invention described in Non-Patent Document 1, since the charge of the nanowire is fixed, the nanowire cannot release the captured exosome itself. In other words, exosomes cannot be recovered without being destroyed. For example, exosomes gathered on nanowires are exposed to a surfactant, which destroys the cell wall. As a result, the miRNA in the exosome is recovered from the cell fluid inside the exosome. Therefore, the invention described in Non-Patent Document 1 cannot be applied when culturing is assumed after collection such as immune cell capture.

On the other hand, the filter 20 according to the present embodiment adsorbs the target substance by the electric charge and releases the charge, or releases the adsorption by the charge of the opposite polarity, so that the target substance is not chemically affected. .. In this way, the filter 20 can be recovered as it is without destroying the target substance, and thus can be cultured after collection.

Further, if there is no insulator film 24 in the portion of the conductor 23 that comes into contact with the liquid, even if the target substance can be adsorbed on the conductor 23, the liquid is electrolyzed and bubbles are generated. The generated bubbles clog the filter 20. This makes it difficult for the liquid to flow through the flow path of the filter 20, and thus reduces the efficiency of collecting and separating the filter 20.

On the other hand, if the portion of the conductor 23 that comes into contact with the liquid is covered with the insulator film 24, no electric charge is transferred between the filter 20 and the liquid even if a DC voltage is applied. Therefore, electrolysis of the liquid does not occur. Therefore, the filter 20 does not generate air bubbles, so that clogging can be prevented. In particular, by using a process capable of forming a uniform thin film such as the ALD method, the filter 20 can generate an electric charge sufficient to adsorb the target substance on the insulator film 24 without electrolysis.

In the present embodiment, the distribution unit 21 has a mesh structure, but the present invention is not limited to this. The distribution unit 21 may have a porous structure, for example, as long as the liquid can circulate. In the case of the porous structure, the structure of the conductor 23 is complicated and the contact area with the liquid increases, so that the target substance is more likely to come into contact with the filter 20 than the mesh structure. Therefore, in the case of a porous structure, the collection efficiency of the target substance is improved.

Further, the size of the opening of the flow path 25 of the mesh structure in the filter 20 can be made larger than the target substance 30 as shown in FIG. 3, for example. The filter 20 does not collect by filtering the substance 30 with the size of the opening of the flow path 25 smaller than the size of the substance 30, but collects by the force of attracting the substance 30 of the filter 20. Since the substance 30 is smaller than the size of the opening of the flow path 25 having a mesh structure, the filter 20 can prevent clogging. Further, the larger the size of the opening of the flow path 25, the easier it is to manufacture the filter 20. The size of the opening of the flow path 25 can be adjusted according to conditions such as the size of the target substance to be collected.

The voltage applied to the filter 20, the flow velocity of the liquid passing through the filter 20, the flow rate, the thickness of the insulator film 24, and the like can also be appropriately adjusted according to conditions such as the size of the target substance to be collected. Further, the filter device 100 can control the selectivity of the target substance to be collected according to the flow velocity of the liquid passing through the filter 20, the voltage applied to the filter 20, or the zeta potential of the target substance.

Although the filter device 100 is provided with one filter 20 in the present embodiment, it may be provided with a plurality of filters 20. When the filter device 100 includes a plurality of filters 20, the portion where the liquid comes into contact with the insulator film 24 of the filter 20 increases. Therefore, the filter device 100 can collect more target substances.

Although the filter device 100 was used to collect the target substance in the present embodiment, it can also be used for other purposes. The filter device 100 can be used, for example, for separation, concentration, medium exchange in culture, bacterial inspection, and the like.

The concentration method using the filter device 100 will be described. For example, a case where 100 mL (concentration: 10 cells / mL) of a liquid containing 1000 bacteria is concentrated 10 times will be described. First, 100 mL of a liquid containing bacteria is passed through a filter 20 to which a positive voltage is applied, and the bacteria are adsorbed on the filter 20. After adsorbing all the bacteria in 100 mL of the liquid on the

filter

20, 10 mL of the eluate is passed through the filter 20 to which a negative voltage is applied. As a result, bacteria are desorbed from the filter 20 and flow out together with the eluate to the outside of the filter device 100. By collecting the 10 mL eluate flowing out of the

filter device

100, 10 mL of a liquid containing 1000 bacteria (concentration: 100 cells / mL) can be obtained. That is, the filter device 100 can also be used for concentrating the target substance. The separation using the filter device 100 is almost the same as the bacterial inspection method described below, and thus the description thereof will be omitted.

Next, a method for inspecting bacteria using the filter device 100 will be described. 4 (A) to 4 (C) are diagrams for explaining a method for inspecting bacteria using the filter device 100.

A method of inspecting a liquid containing a plurality of bacteria using the filter device 100 will be described. The liquid to be tested contains, for example, two bacteria A41 and a bacterium B42 with different zeta potentials. The user first applies a positive voltage (V1) to the conductor 23 of the filter 20. As shown in FIG. 4A, bacteria A41 and bacteria B42 are adsorbed on the surface of the insulator film 24 of the filter 20.

Next, the user applies a positive voltage (V2) smaller than V1 to the conductor 23. As a result, the bacterium B42 is eliminated from the surface of the insulator film 24 as shown in FIG. 4 (B). Therefore, the user can collect and inspect only the bacterium B42 downstream. Further, the user applies a positive voltage (V3) smaller than V2 to the conductor 23. As a result, as shown in FIG. 4C, the bacterium A41 is eliminated from the surface of the insulator film 24. Therefore, the user can collect and inspect only the bacterium A41 downstream.

In this way, the user can separate and inspect each bacterium having a different zeta potential using the filter device 100. When the filter device 100 contains three or more types of bacteria, it can be similarly separated. It is also possible to set V3 to 0V or a negative voltage. It is also possible to gradually separate bacteria having different zeta potentials by gradually changing the voltage from V1 toward a negative voltage.

Next, the medium exchange using the filter device 100 will be described. 5 (A) to 5 (C) are diagrams for explaining medium exchange using the filter device 100. Note that FIGS. 5A to 5C show only the filter 20 of the filter unit 101 in the filter device 100, and the rest will be omitted.

In the medium exchange using the filter device 100, the user uses the medium exchange unit 70 including the filter device 100. As shown in FIG. 5A, the medium exchange unit 70 includes a filter unit 101, a container 51, a container 52, a tube 57, a container 53, a valve 54, a valve 55, a valve 56, a tube 57, and a tube 58. The filter unit 101 is connected to one end of each of the pipe 57 and the pipe 58. A pump (not shown) circulates the liquid through the pipe 57 and the pipe 58 to the filter 20 of the filter unit 101.

The pipe 57 has a first end 61 on the side that is not connected to the filter unit 101. The tube 58 has a second end 62 and a third end 63 that are bifurcated on the side not connected to the filter unit 101. The first end 61 is arranged inside the container 51, the second end 62 is arranged inside the container 52, and the third end 63 is arranged inside the container 53, respectively. The valve 54 is arranged between the filter unit 101 and the first end 61 of the pipe 57. The valve 55 is arranged between the filter unit 101 and the second end 62 of the pipe 58. The valve 56 is arranged between the filter unit 101 in the pipe 58 and the third end 63. The valve 54, the valve 55, and the valve 56 open and close the pipe 57 and the pipe 58, respectively.

The culture solution is filled in the container 51. The culture medium contains old medium and cells. The new medium is filled in container 53. Further, the container 52 is in an empty state where nothing is filled.

The user first opens the valve 54 and the valve 55 and closes the valve 56. Next, the user drives a pump (not shown) to circulate the liquid in the direction of the arrow in FIG. 5 (B). The culture solution in the container 51 is sucked up from the first end 61 and moves from the second end 62 to the container 52 via the filter 20. At this time, a positive voltage is applied to the filter 20. As a result, the cells in the culture medium are adsorbed on the filter 20, and the other old culture medium is moved to the container 52.

Next, the user first sets the valve 54 and the valve 56 in the open state and the valve 54 in the closed state. Subsequently, the user drives a pump (not shown) to circulate the liquid in the direction of the arrow in FIG. 5 (C). The medium in the container 53 is sucked up from the third end 63 and moves from the first end 61 to the container 51 through the filter 20. At this time, no voltage is applied to the filter 20, or a negative voltage is applied to the filter 20. As a result, the cells adsorbed on the filter 20 are detached from the filter 20 and moved to the container 51 together with the new medium. Therefore, the cells do not remain in the filter 20, and the recovery rate of the cells is improved. Further, the flow path 25 of the filter 20 can be designed to be large for cells. Therefore, it is possible to prevent cells from clogging the filter 20. Therefore, the user can smoothly change the medium. As described above, the user can exchange the medium by using the filter device 100.

When exchanging the medium using a pipette and a centrifuge as in the conventional case, the operator precipitates the cells by centrifuging the culture solution put in the centrifuge tube, and sucks up the supernatant culture solution with the pipette. In this case, the operation of transferring to a plurality of centrifuge tubes may occur and the cells may be exposed to air, and there is a problem that the yield is lowered due to the transfer. Furthermore, in the conventional medium exchange, there are cases where cells cannot be sufficiently separated by centrifugation, and the yield may decrease due to an erroneous operation of the pipette. For this reason, in the conventional medium exchange, it is necessary for the operator to become accustomed to the medium and to perform careful operation.

On the other hand, the medium exchange unit 70 can be used for, for example, anaerobic bacteria by making all the spaces closed. Further, since the operation of transferring to a plurality of centrifuge tubes can be omitted, the yield and efficiency are improved. Further, since the operator does not operate the pipette, the burden and time of the operator can be saved. Therefore, the method for exchanging the medium using the filter device 100 is excellent in yield and efficiency, and can exchange the medium in a stable state without being exposed to the outside air.

Hereinafter, Examples 1 and 2 using the filter 20 according to the present invention will be described.

(Example 1) Collection example using a mesh filter First, a stainless steel mesh filter with a mesh opening of 77 μm was prepared and stacked in three layers. _{An alumina (Al 2} O ₃ ) film was formed on the laminated mesh filter by the ALD method. The thickness of the alumina film was about 30 nm. As a result, a mesh filter coated with an insulator film was obtained. The obtained mesh filter was set in the filter device.

Next, a test solution containing yeast was prepared by adding 0.5 g of dry yeast to 1 L of pure water and stirring the mixture. By driving the pump, the test solution was flowed through the mesh filter at a flow velocity of 1.8 ml / min. At this time, a voltage of −10 V was applied to the mesh filter. The liquid that had passed through the mesh filter was recovered, and 0.1 mL of the recovered liquid was sandwiched between two slide glasses and observed at a magnification of 200 times using a microscope (VHX-5000, manufactured by KEYENCE). In the observation, the number of yeasts present in the field of view 1.6 × 1.2 mm was counted. Next, a similar test was performed with a voltage of + 20 V applied to the mesh filter.

FIG. 6 is a graph showing the results of Example 1. As shown in FIG. 6, when a voltage of −10 V was applied to the mesh filter, the number of yeasts counted was 1083. On the other hand, when a voltage of + 20 V was applied to the mesh filter, the number of yeasts counted was 79. That is, when a negative voltage was applied to the mesh filter, yeast was desorbed from the mesh filter and flowed out, and conversely, when a positive voltage was applied, yeast was adsorbed on the mesh filter. As described above, it was confirmed that a certain amount of yeast can be collected by applying a positive voltage to the mesh filter using the stainless steel mesh filter formed by the ALD method. The collection efficiency using the mesh filter was 93%.

(Example 2) Collection example using a porous body First, a stainless steel porous body having a filtration diameter of 10 μm and a thickness of 3 mm was prepared. _{An alumina (Al 2} O ₃ ) film was formed on the stainless steel porous body by the ALD method. The thickness of the alumina film was about 30 nm. As a result, a stainless steel porous body coated with an insulator film was obtained. The obtained stainless steel porous body was set in a filter device.

Next, a test solution containing yeast was prepared by adding 0.5 g of dry yeast to 1 L of pure water and stirring the mixture. By driving the pump, the test solution was flowed through the stainless steel porous body at a flow velocity of 0.5 ml / min. First, a voltage of −10 V was applied to the stainless steel porous body. In Example 2, the test liquid was allowed to flow through the stainless steel porous body, and the liquid that passed through the stainless steel porous body was allowed to flow while being observed with a microscope (VHX-5000, manufactured by KEYENCE) at a magnification of 200 times. In the observation, the number of yeasts passing through the range of 1.6 × 1.2 mm in the field of view was counted in 10 seconds. Next, the same test was performed with a voltage of + 20 V applied to the stainless steel porous body for about 120 seconds. Subsequently, the same test was carried out with a voltage of −10 V applied to the stainless steel porous body again.

FIG. 7 is a graph showing the results of Example 2. As shown in FIG. 7, when a voltage of −10 V was first applied to the stainless steel porous body, the number of yeasts counted was about 200. Subsequently, when a voltage of + 20 V was applied to the stainless steel porous body, the number of yeasts counted was two. Furthermore, when a voltage of −10 V was applied to the stainless steel porous body again, the number of yeasts counted was about 20000.

In this way, as in the case of using the mesh filter, when a negative voltage is applied to the stainless steel porous body, it flows out without being adsorbed by the stainless steel porous body, and conversely, when a positive voltage is applied, yeast bacteria become the stainless steel porous body. Adsorbed to. It has been confirmed that yeast can collect a certain amount of yeast by applying a positive voltage to the stainless porous body even if the stainless porous body coated with _{Al 2} O _{3 formed} by the ALD method is used. Was done. The collection efficiency using the stainless steel porous body was 99%. From this, it was confirmed that the collection efficiency was higher when the stainless steel porous body was used as the filter as compared with the mesh filter of Example 1.

Further, by applying a negative voltage to the stainless steel porous body after adsorbing yeast on the stainless steel porous body by flowing a test solution in a state where a positive voltage is applied to the stainless steel porous body for a predetermined time (here, about 120 seconds). , The adsorbed yeast is desorbed from the stainless steel porous body all at once and flows out at once. As a result, a effluent in which yeast is concentrated is obtained. Therefore, it was confirmed that a yeast concentrate having a concentration corresponding to the time for collecting yeast can be obtained.

The above description of the embodiment should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is shown not by the above-described embodiment but by the scope of claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope equivalent to the claims.

10 ... Fixture 11 ... Joint (side wall of flow path)
12 ... Socket 13 ... Internal space 16 ... Voltage application part 20 ... Filter 21 ... Distribution part (liquid passing part)
22 ... Frame part 23 ... Conductor 24 ... Insulator film 25 ... Flow path 100 ... Filter device 101 ... Filter unit 102 ... DC power supply 103 ... Control unit

Claims

Conductors that can flow liquids and
An insulator film that covers a portion of the conductor that comes into contact with the liquid,
It is located on a portion of the surface of the conductor that the liquid does not come into contact with, and includes a voltage applying portion for applying a voltage from the outside.
filter.
The conductor has a portion having a mesh structure or a porous structure.
The filter according to claim 1.
The insulator film contains titanium, alumina, silica, hafnia, zinc oxide or zirconia.
The filter according to claim 1 or 2.
The insulator film is formed by an atomic layer deposition method or an anodization treatment.
The filter according to any one of claims 1 to 3.
The voltage application portion is formed by removing a part of the insulator film.
The filter according to any one of claims 1 to 4.
The side wall of the flow path that constitutes the flow path for flowing the liquid,
With a conductor capable of flowing liquid,
The conductor is a fixture fixed to the side wall of the flow path, a liquid passage portion arranged in the flow path, an insulator film covering the liquid passage portion, and an external voltage applied to the fixture. A voltage application unit for
Filter unit.
The voltage applying unit applies a voltage from the outside through the fixture.
The filter unit according to claim 6.
With the filter unit according to claim 6 or 7.
A DC power supply that applies a voltage to the fixture.
Filter device.
A control unit for controlling the DC voltage of the DC power supply is further provided.
The filter device according to claim 8.
The control unit switches the DC voltage between positive and negative.
The filter device according to claim 9.