A micro / nano filtration membrane, its preparation method, and filtration device

Abstract

A micro / nano filtration membrane, its preparation method, and a filtration device are disclosed. The micro / nano filtration membrane comprises an inorganic material support substrate and a filtration membrane material. The filtration membrane material is stacked and fixed to the support substrate. The support substrate has multiple filtration windows, and the filtration membrane material has filtration channels in the area directly opposite each filtration window. The maximum inner diameter of the filtration channels is smaller than the minimum inner diameter of the filtration windows. A hydrophilic material layer is formed on the surface of the composite structure formed by the support substrate and the filtration membrane material. Using the support substrate to support and fix the filtration membrane material ensures sufficient mechanical strength to prevent breakage during filtration. It also effectively reduces the thickness of the filtration membrane, shortening the length of the filtration channels, which helps reduce liquid resistance and filtration loss. Simultaneously, the hydrophilic material layer enhances the hydrophilicity of the filtration membrane, allowing sample liquid to pass quickly through the filtration channels, thus improving filtration efficiency and quality.

Description

Technical Field

[0001] This invention relates to the field of filtration technology, specifically to a micro / nano filtration membrane, its preparation method, and a filtration device. Background Technology

[0002] Membrane filtration is a precision separation technology widely used in fields such as biology, medicine, chemical industry, and materials. It uses particle size as a distinguishing factor. When the fluid to be filtered passes through the filter membrane, particles with a particle size larger than the filter pores are retained by the filter membrane, while particles with a particle size smaller than the filter pores pass through the filter membrane, thereby achieving the purpose of separation or purification.

[0003] Currently, porous membranes made of organic polymer materials are commonly used as filtration membranes, such as polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, and polyethersulfone. However, filtration membranes made of organic polymer materials are prone to adsorption effects on the samples to be filtered (such as biological samples), resulting in filtration loss. Summary of the Invention

[0004] The main technical problem solved by this invention is to provide a micro / nano filtration membrane, its preparation method, and a filtration device using the micro / nano filtration membrane, so as to improve filtration performance.

[0005] According to a first aspect, one embodiment provides a micro / nano filtration membrane, comprising:

[0006] An inorganic material support substrate has a plurality of filter windows disposed through the thickness direction of the micro / nano filter membrane, wherein the length of the filter window in the thickness direction is greater than or equal to 50 micrometers, and the minimum inner diameter of the filter window is greater than or equal to one-third of the length of the filter window.

[0007] And inorganic material filter membrane, the filter membrane is stacked along the thickness direction and fixed to the support substrate, the filter membrane has filter channels in the area facing each filter window, the filter channels are arranged to penetrate the filter membrane along the thickness direction, the length of the filter channels in the thickness direction is less than or equal to 20 micrometers, and the maximum inner diameter of the filter channels is less than the minimum inner diameter of the filter window.

[0008] The supporting substrate and the filter membrane form a combined structure, and at least the wall surface of the filter channels in the combined structure is formed with a hydrophilic material layer.

[0009] In one embodiment, the material of the filter membrane and / or the material of the supporting substrate is silicon or silicon nitride, and the hydrophilic material layer is a silicon dioxide layer formed on the surface of the combined structure using a high-temperature thermal oxidation process; or

[0010] The material of the filter membrane and / or the supporting substrate is any one of gallium nitride, boron nitride, molybdenum disulfide, and graphene, and the hydrophilic material layer is a silicon dioxide layer formed on the surface of the combined structure using a chemical vapor deposition process.

[0011] In one embodiment, the thickness of the silicon dioxide layer is set to be less than or equal to 20 nanometers, and / or the hydrophilic contact angle of the silicon dioxide layer is set to be less than or equal to 45°.

[0012] In one embodiment, the filter membrane material has a plurality of filter channels with the same inner diameter in the area facing each of the filter windows, and the pore size error of the filter channels is less than or equal to ±2 nanometers.

[0013] In one embodiment, the filter window is an equal-diameter hole that penetrates the support substrate, and the cross-sectional shape of the filter window is circular, elliptical, or polygonal.

[0014] Alternatively, the filter window may be a variable diameter hole that passes through the support substrate, and the inner diameter of the filter window gradually increases from the end of the filter window closer to the filter membrane to the end farther away from the filter membrane, and the cross-sectional shape of the filter window may be circular, elliptical, or polygonal.

[0015] In one embodiment, the material further includes a reinforcing matrix made of inorganic material, wherein the supporting matrix is ​​stacked and fixed to the reinforcing matrix along the thickness direction, and the filter membrane is located on the side of the supporting matrix facing away from the reinforcing matrix; wherein:

[0016] The reinforcing substrate has a plurality of connecting windows that are disposed through the thickness direction. The filter window is located in the area of ​​the supporting substrate and each of the connecting windows, and the maximum inner diameter of the filter window is smaller than the minimum inner diameter of the connecting window.

[0017] According to a second aspect, one embodiment provides a filtration device, comprising:

[0018] A sample container having a first container wall and a sample space defined by the first container wall, the sample space being for accommodating a sample to be filtered, wherein at least a portion of the first container wall is made of the micro / nano filtration membrane described in the first aspect, the filter material of the micro / nano filtration membrane being located on the side where the sample space is located; and

[0019] A collection container having a second container wall and a collection space defined by the second container wall, wherein a sample container is inserted into the collection space such that the collection container can collect the filtrate formed after filtration by the sample container.

[0020] In one embodiment, the system further includes a waste liquid container; at least a portion of the wall of the second container is made of the micro / nano filter membrane described in the first aspect, the filter membrane material of the micro / nano filter membrane is located on the side where the collection space is located, and the inner diameter of the filter pores of the second container wall is set to be smaller than the inner diameter of the filter pores of the first container wall.

[0021] The waste liquid container is placed outside the collection container to collect the filtrate formed after filtration by the collection container.

[0022] In one embodiment, the sample container is configured to rotate relative to the collection container about a preset axis, and / or the collection container is configured to rotate relative to the waste container about a preset axis.

[0023] According to a third aspect, a method for preparing the micro / nano filtration membrane described in the first aspect includes:

[0024] A silicon dioxide layer is formed on the surface of the combined structure using a high-temperature thermal oxidation process; in the combined structure, the materials of the supporting substrate and the filter membrane are either silicon or silicon nitride.

[0025] The combined structure with a silicon dioxide layer formed on its surface is placed in a mixed solution of concentrated sulfuric acid and hydrogen peroxide, and after soaking for a preset time, it is taken out to obtain the micro-nano filtration membrane.

[0026] or

[0027] A silicon dioxide layer is formed on the surface of the composite structure using a chemical vapor deposition process; in the composite structure, the material of the supporting substrate and the filter membrane is any one of gallium nitride, boron nitride, molybdenum disulfide, and graphene;

[0028] The combined structure with a silica layer formed on its surface is placed in a mixed solution of concentrated sulfuric acid and hydrogen peroxide, and after soaking for a preset time, it is taken out to obtain the micro-nano filter membrane.

[0029] The micro / nano filtration membrane according to the above embodiments includes an inorganic material support substrate and a filtration membrane material. The filtration membrane material is stacked and fixed to the support substrate. The support substrate has multiple filtration windows, and the area of ​​the filtration membrane material opposite each filtration window has filtration channels. The maximum inner diameter of the filtration channels is smaller than the minimum inner diameter of the filtration windows. A hydrophilic material layer is formed on the surface of the combined structure formed by the support substrate and the filtration membrane material. Using the support substrate to support and fix the filtration membrane material ensures sufficient mechanical strength to prevent problems such as membrane breakage during filtration. It also effectively reduces the thickness of the filtration membrane material, shortening the length of the filtration channels, which helps reduce liquid resistance and filtration loss. Simultaneously, the hydrophilic material layer enhances the hydrophilicity of the filtration membrane, allowing the sample liquid to pass quickly through the filtration channels, thus creating conditions for improving filtration efficiency and quality. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the cross-sectional structure of a micro / nano filtration membrane according to one embodiment (I).

[0031] Figure 2 This is a schematic diagram of the cross-sectional structure of a micro / nano filtration membrane according to one embodiment (II).

[0032] Figure 3 A cross-sectional structural schematic diagram of a filter device according to one embodiment (I).

[0033] Figure 4 This is a cross-sectional structural schematic diagram (II) of a filter device according to one embodiment.

[0034] Figure 5 This is a schematic diagram of the particle size distribution of a test sample in one embodiment (I).

[0035] Figure 6 This is a schematic diagram (II) of the particle size distribution of a test sample in one embodiment.

[0036] In the picture:

[0037] 10. Sample container; 10a. First container wall; 10b. Sample space; 20. Collection container; 20a. Second container wall; 20b. Collection space; 30. Micro / nano filter membrane; 31. Supporting substrate; 31a. Filter window; 32. Filter membrane material; 32a. Filter channel; 33. Hydrophilic material layer; 34. Reinforcing substrate; 34a. Connecting window; 40. Waste liquid container. Detailed Implementation

[0038] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. Similar elements in different embodiments are referred to by associated similar element reference numerals. In the following embodiments, many details are described to facilitate a better understanding of the present application. However, those skilled in the art will readily recognize that some features may be omitted in different situations, or may be replaced by other elements, materials, or methods. In some cases, certain operations related to the present application are not shown or described in the specification. This is to avoid obscuring the core parts of the present application with excessive description. For those skilled in the art, detailed description of these related operations is not necessary; they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0039] Furthermore, the features, operations, or characteristics described in the specification can be combined in any suitable manner to form various embodiments. At the same time, the steps or actions in the method description can be rearranged or adjusted in a manner obvious to those skilled in the art. Therefore, the various orders in the specification and drawings are only for the clear description of a particular embodiment and do not imply a necessary order, unless otherwise stated that a particular order must be followed.

[0040] The serial numbers assigned to components in this document, such as "first" and "second," are used only to distinguish the described objects and have no sequential or technical meaning. The terms "connection" and "linkage" used in this application, unless otherwise specified, include both direct and indirect connections (linkages).

[0041] Example 1

[0042] Please see Figures 1 to 3 The first embodiment of this application provides a filtration device that can be used for the separation and filtration of micro-nano particles or the purification of liquids to remove impurities. For example, by filtering micro-nano particles with a particle size larger than a preset size, it can collect micro-nano particles with a particle size smaller than a preset size. The filtration device includes a sample container 10, a collection container 20, and a micro-nano filter membrane 30.

[0043] It should be noted that the "micro-nanoparticles" mentioned in this application refer to particles with sizes at the micrometer and nanometer levels, typically including organic particles, inorganic particles, magnetic particles, silica particles, agarose gel particles, styrene particles, metal particles, colloidal particles, particles conjugated with molecules, particles conjugated with biomolecules, particles conjugated with immunoglobulins, particles conjugated with nucleic acids, biological particles, biological cells, blood cells, sperm, egg cells, microbial cells, bacterial cells, fungal cells, viruses, subcellular organelles, mitochondria, cell nuclei, chloroplasts, lysosomes, ribosomes, atomic particles, ionic particles, molecular particles, polymer particles, nucleic acids and their chemical variants, deoxyribonucleic acid and its chemical variants, nucleic acids and their chemical variants, proteins and their chemical variants, etc.

[0044] Please see Figure 3 The sample container 10 has a first container wall 10a and a sample space 10b. The sample space 10b is mainly used to contain or hold the sample to be filtered (e.g., a biological sample). The sample space 10b is defined by the first container wall 10a and has a spatial structure with a predetermined shape and volume. Similar to the sample container 10, the collection container 20 has a second container wall 20a and a collection space 20b. The collection space 20b is mainly used to collect the filtrate formed after filtration by the sample container 10. The collection space 20b is defined by the second container wall 20a and has a spatial structure with a predetermined shape and volume.

[0045] In specific implementation, the sample container 10 and the collection container 20 can adopt the same or similar structural forms. Taking the sample container 10 as an example, its overall outline can be a circular sleeve structure. In this case, the first container wall 10a can be understood as the combination of the circumferential side walls and the axial bottom wall of the sample container 10, thereby defining the sample space 10b in the shape of a circular cylinder. The overall outline of the sample container 10 can also be a rectangular sleeve structure. In this case, the first container wall 10a can be understood as the combination of the four side walls and the bottom wall of the sample container 10, thereby defining the sample space 10b in the shape of a square cylinder. Of course, according to actual needs, the sample container 10 and the collection container 20 can also adopt other suitable outline shapes with reference to the prior art.

[0046] Please see Figure 1 and Figure 3 The micro-nano filter membrane 30 constitutes at least a portion of the first container wall 10a. In other words, at least a portion or all of the first container wall 10a is made of the micro-nano filter membrane 30. For example, corresponding pores can be opened on the first container wall 10a. The micro-nano filter membrane 30 covers the pores and is arranged on one side of the first container wall 10a located in the sample space 10b. Alternatively, the first container wall 10a is entirely made of the micro-nano filter membrane 30 so as to define or enclose the sample space 10b of the sample container 10 by means of the micro-nano filter membrane 30.

[0047] Please see Figure 1 The micro / nano filter membrane 30 includes a support substrate 31, a filter membrane material 32, and a hydrophilic material layer 33. Both the support substrate 31 and the filter membrane material 32 are made of inorganic materials, such as silicon, silicon nitride, gallium nitride, boron nitride, molybdenum disulfide, and graphene. The support substrate 31 has multiple filter windows 31a extending along the thickness direction of the micro / nano filter membrane 30. The filter membrane material 32 is stacked and fixed to the support substrate 31 along the thickness direction of the micro / nano filter membrane 30, and each filter membrane material 32 has at least one filter channel 32a extending along its thickness direction in the area facing each filter window 31a. The filter membrane material 32 and the support substrate 31 form a combined structure, and the hydrophilic material layer 33 is formed on the surface of this combined structure, for example, at least on the wall surface of the filter channel 32a.

[0048] In specific implementation, the length of the filter window 31a in the thickness direction is greater than or equal to 50 micrometers, and the minimum inner diameter of the filter window 31a is greater than or equal to one-third of the length of the filter window 31a; the length of the filter channel 32a in the thickness direction is less than or equal to 20 micrometers, and the maximum inner diameter of the filter channel 32a is set to be less than or equal to the minimum inner diameter of the filter window 31a.

[0049] For example, the support substrate 31 adopts a silicon material sheet structure with a thickness of 250 micrometers, and the filter window 31a is a circular through-hole with a pore size of 100 micrometers that penetrates the support substrate 31; correspondingly, the filter membrane 32 adopts a silicon nitride membrane structure with a thickness of 400 nanometers, and the filter membrane 32 and the area corresponding to each filter window 31a are provided with multiple filter channels 32a with a pore size of 250 nanometers; the hydrophilic material layer 33 is formed on the surface of the combined structure formed by the support substrate 31 and the filter membrane 32 (including the wall surface of the filter channel 32a).

[0050] Based on this, the micro / nano filter membrane 30 can be fixed to (e.g., bonded with sealant) the first container wall 10a using the support substrate 31, or a basic structure forming the first container wall 10a can be constructed, such that the filter membrane 32 is located on the side where the sample space 10b is located. The configured micro / nano filter membrane 30 allows the sample container 10 to filter micro / nano particles with a particle size larger than a preset size, and the filtrate formed through the micro / nano filter membrane 10a is collected in the collection container 20.

[0051] Firstly, by using a relatively thick support substrate 31 to provide structural support and fixation for the filter membrane 32, it is possible to ensure that the filter membrane 32 has sufficient mechanical strength or pressure resistance, making it less prone to rupture or damage under pressure. At the same time, it also creates conditions for significantly reducing the thickness of the filter membrane 32. For example, a filter membrane 32 with a thickness of several micrometers can be used, which can significantly shorten the length of the filter channel 32a. As a result, it is not only beneficial to reduce the liquid flow resistance of the filter membrane 32, allowing the sample to pass through the micro-nano filter membrane 30 quickly for separation and filtration, thus improving filtration efficiency, but also to prevent particles in the sample from adhering to the filter channel 32 and causing filtration loss.

[0052] Secondly, by utilizing the hydrophilic material layer formed on the surface of the combined structure formed by the support substrate 31 and the filter membrane 32, the hydrophilicity of the micro-nano filter membrane 30 can be effectively improved, making it easier for the sample to pass through the micro-nano filter membrane 30 quickly for separation and filtration. On the other hand, it can also reduce the charge at the solid-liquid interface, so that no potential points are formed on the surface of the micro-nano filter membrane 30, thereby preventing micro-nano particles in the sample from being electrostatically attracted to the surface of the micro-nano filter membrane 30.

[0053] Thirdly, the main structure of the micro / nano filter membrane 30 is formed by combining the inorganic material support substrate 31 and the inorganic material filter membrane 32. This not only makes full use of the good ductility of the inorganic material itself to improve the overall mechanical strength of the micro / nano filter membrane 30, but also takes advantage of the fact that inorganic materials have poorer adsorption of micro / nano particles compared to organic materials, thus ensuring that samples pass through the filter membrane quickly and reducing sample filtration loss. In addition, the filter membrane 32 made of inorganic materials has good film-forming properties, and the filter channels 32a formed are evenly distributed and have consistent pore sizes. This makes the micro / nano filter membrane 30 have good selectivity for particle size, which can effectively prevent some particles with a particle size larger than the pore size of the filter channel 32a from accidentally passing through the filter membrane, while some particles with a particle size smaller than the pore size of the filter channel 32a are trapped.

[0054] In one embodiment, please refer to Figure 1 The hydrophilic material layer 33 is a silicon dioxide material layer with a thickness of less than or equal to 20 nanometers and a hydrophilic contact angle of less than or equal to 45°. In specific implementations, depending on the specific material differences between the supporting substrate 31 and the filter membrane 32, a corresponding process can be used to form a silicon dioxide layer on the surface of the combined structure.

[0055] For example, when the support substrate 31 and the filter membrane 32 are made of materials such as silicon or silicon nitride, a silicon dioxide layer of a predetermined thickness can be naturally formed on the surface of the combined structure by means of a high-temperature thermal oxidation process. Then, by soaking the membrane in a mixed solution of concentrated sulfuric acid and hydrogen peroxide with a volume ratio of 2:1 for a predetermined time (e.g., 2 hours), a micro-nano filter membrane 30 with a hydrophilic material layer 33 can be obtained.

[0056] For example, when the support substrate 31 and the filter membrane 32 are made of materials such as gallium nitride, boron nitride, molybdenum disulfide, and graphene, a silicon dioxide layer of a predetermined thickness can be deposited on the surface of the combined structure by chemical vapor deposition. After soaking in a mixed solution of concentrated sulfuric acid and hydrogen peroxide with a volume ratio of 3:1 for a predetermined time (e.g., 1 hour), it can be stored in a pure aqueous solution to obtain a micro-nano filter membrane 30 with a hydrophilic material layer 33.

[0057] For example, when both the support substrate 31 and the filter membrane material 32 are made of silicon oxide, there is no need to make special treatment to the structure of the two or their combination. By using the surface of the two themselves as the hydrophilic material layer 33, the micro-nano filter membrane 30 can have good hydrophilicity.

[0058] In one embodiment, please refer to Figure 1 The filter window 31a is a variable-diameter hole that passes through the support substrate 31. The inner diameter of the filter window 31a gradually increases from the end of the filter window 31a closer to the filter membrane 32 to the end farther away from the filter membrane 32, and the cross-sectional shape of the filter window 31a is approximately circular, elliptical, or polygonal, such as a rectangle. It can be understood that the filter window 31a is similar to a conical hole structure.

[0059] On the one hand, by utilizing the structural feature that the inner diameter of the filter window 31a is smaller at one end closer to the filter membrane 32 than at the other end, the surface area occupied by the filter window 31a on the side of the support substrate 31 facing the filter membrane 32 can be reduced, so that the support substrate 31 can stably support and fix the filter membrane 32. On the other hand, after the sample passes through the filter membrane 32 through the filter channel 32a, the adhesion of particles in the sample to the filter channel 31a can be minimized, ensuring the separation and filtration effect of the micro-nano filter membrane 30.

[0060] In other embodiments, the filter window 31a is a uniform diameter hole that passes through the support substrate 31. The cross-sectional shape of the filter window 31a can be circular, elliptical, or polygonal, such as rectangular, depending on actual needs. Alternatively, the filter window 31a can adopt a multi-stage stepped hole structure, with the inner diameter of the filter window 31a gradually increasing from the end closer to the filter membrane 32 to the end farther away from the filter membrane 32.

[0061] In one embodiment, please refer to Figure 2The micro / nano filter membrane 30 also includes an inorganic reinforcing substrate 34, which may be made of the same or different inorganic material as the supporting substrate 31 and / or the filter membrane material 32. The supporting substrate 31 is stacked and fixed to the reinforcing substrate 34 along the thickness direction of the micro / nano filter membrane 30, while the filter membrane material 32 is located on the side of the supporting substrate 31 facing away from the reinforcing substrate 34. The reinforcing substrate 34 has a plurality of connecting windows 34a that are arranged through the thickness direction of the micro / nano filter membrane 30. The filter windows 31a are located in the area of ​​the supporting substrate 31 and each connecting window 34a, and the maximum inner diameter of the filter window 31a is smaller than the minimum inner diameter of the connecting window 34a.

[0062] In practical implementation, the filter window 31a and the connecting window 34a can be set one-to-one, and each connecting window 34a can also correspond to multiple filter windows 31a; and the cross-sectional shapes of the two can be the same or different. By reinforcing the substrate 34, the overall mechanical strength or pressure resistance of the micro / nano filter membrane 30 can be further enhanced, avoiding problems such as rupture and damage to the filter membrane material 32; at the same time, it also makes the micro / nano filter membrane 30 suitable for scenarios with large external pressure requirements.

[0063] For example, the reinforcing substrate 34 adopts a silicon material sheet structure with a thickness of 500 micrometers. The connecting window 34a is a square through-hole with a pore size of 500 micrometers * 500 micrometers, which is set through the reinforcing substrate 34. The number of connecting windows 34a is set to 100, and the pore spacing between the connecting windows 34a is 1.5 mm. The supporting substrate 31 adopts a silicon nitride material sheet structure with a thickness of 2.5 micrometers. The filter window 31a is a square through-hole with a pore size of 1 micrometer * 1 micrometer. 100 filter windows 31a are set in the area of ​​the supporting substrate 31 opposite each connecting window 34a. The pore spacing between the filter windows 31a is 50 micrometers. The filter membrane 32 adopts a graphene membrane with a thickness of 10 nanometers. In the area of ​​the filter membrane 32 opposite each filter window 31a, 25 filter channels 32b with an inner diameter of 30 nanometers are set. The pore spacing between the filter channels 32b is 100 nanometers.

[0064] A 10-nanometer-thick silicon dioxide layer (i.e., hydrophilic material layer 33) is deposited on the surface of the combined structure formed by the support substrate 31, the filter membrane material 32 and the reinforcing substrate 34 using chemical vapor deposition. After soaking in a mixed solution of concentrated sulfuric acid and hydrogen peroxide with a volume ratio of 3:1 for 1 hour, it is placed in a pure aqueous solution and stored for a preset time to obtain a micro-nano filter membrane 30 with a filtration pore size of 10 nanometers.

[0065] In one embodiment, please refer to Figure 3The sample container 10 is configured to rotate relative to the collection container 20 around a preset axis. During the process of the sample passing through the micro / nano filter membrane 30, the rotational nature of the sample container 10 relative to the collection container 20 drives the liquid flow parallel to the tangential direction of the filter channel 32a, effectively preventing micro / nano particles with diameters larger than the pore size of the filter channel 32a from clogging the filter channel 32a. In a specific implementation, the sample container 10 can be suspended at the center of the collection space 20b, so that their geometric center lines coincide, and this geometric center line is based on the axis of rotation of the two relative to each other.

[0066] It should be noted that, Figure 2 The hydrophilic material layer is not shown in the image. Figure 3 The bold dashed line represents the axis of rotation, and the bold solid double arrow represents the direction of rotation of the sample container 10.

[0067] Please see Figure 5 and combined Figures 1 to 3 The following test of a filtration device with a filtration pore size of 250 nanometers provided by an exemplary embodiment shows that the filtration device or micro / nano filtration membrane 30 has very significant filtration performance.

[0068] I. The specific structure of this filtration device is as follows.

[0069] Regarding the micro / nano filter membrane 30, it is mainly a combination structure of a silicon material support substrate 31 and a silicon nitride material filter membrane 32.

[0070] The support substrate 31 has the following approximate dimensions: 10 mm in length, 10 mm in width, and 250 μm in thickness. 100 circular filter windows 31a are arranged in an array through the support substrate 31. The pore size of the filter windows 31a is 100 μm, and the pore spacing between the filter windows 31a is 1000 μm.

[0071] The filter membrane 32 has a thickness of 400 nanometers. 900 filter channels 32b are provided in the area of ​​each filter window 31a of the filter membrane 32. When a silicon dioxide layer is formed on the surface of the filter membrane 32 and the supporting substrate 31 through a high-temperature thermal oxidation process, the pore size (diameter) of the filter channel 32b is 250 nanometers, and the pore spacing between the filter channels 32b is 3 micrometers.

[0072] The above-mentioned combined structure was soaked in a mixed solution of concentrated sulfuric acid and hydrogen peroxide with a volume ratio of 2:1 for 2 hours to obtain a micro-nano filter membrane 30 with a pore size of 250 nanometers.

[0073] Regarding the sample container 10, the main body of the sample container 10 is a rectangular structure made of plastic material (outline dimensions: length 12 mm, width 12 mm, height 20 mm); a 10 mm * 10 mm square through hole is provided through each of the five walls of the sample container 10 (i.e., the first container wall 10a). The micro-nano filter membrane 30 with a pore size of 250 nanometers is covered on the corresponding square through hole, and the contact position is sealed with sealant to define the sample space 10b and obtain the sample container 10.

[0074] As for the collection container 20, the collection container 20 is a rectangular container made of plastic material (the outline dimensions are: length 18 mm, width 18 mm, height 20 mm).

[0075] The sample container 10 is suspended inside the collection container 20 to form a filter device with a filtration pore size of 250 nanometers.

[0076] II. The testing process for this filtration device is as follows.

[0077] 1. After diluting the mixed solution of PS microspheres of 100 nm, 150 nm, 250 nm and 300 nm, add it into sample container 10 as the sample to be filtered; seal the port of sample container 10 with a special connector and connect it to a pressurizing device (e.g., a syringe), and push air into sample container 10 through the pressurizing device so that the sample to be filtered passes through the micro-nano filter membrane 30 and enters collection container 20 under pressure.

[0078] 2. The particle size distribution of the filtrate collected in collection container 20 is tested using a testing instrument (e.g., a nano-Coulter apparatus) to obtain the following results: Figure 5 The particle size distribution diagram shown is from Figure 5 As can be seen, all particles with a diameter greater than 250 nanometers in the filtrate were filtered out, which shows that the separation and filtration effect of the micro-nano filter membrane 30 is very significant and the cutoff particle size is very clear.

[0079] 3. During the filtration process, the filter device was rotated at 200 rpm on a rotating instrument. It was observed that the pressurizing device could normally push air into the sample container 10 without increased resistance or difficulty in air introduction. Furthermore, after the operation, inspection of the micro / nano filter membrane 30 revealed no damage. This indicates that the filter device or micro / nano filter membrane 30 retains sufficient mechanical strength or pressure resistance even after repeated use, and maintains excellent separation performance for micro / nano particles.

[0080] Example 2

[0081] Please see Figure 1 , Figure 2 and Figure 4 The filter device provided in Embodiment 2 of this application differs from Embodiment 1 in that a waste liquid container 40 is added, and the collection container 20 is structurally configured with reference to the sample container 10, thereby enabling the filter device to collect micro-nano particles of a specific particle size.

[0082] Specifically, at least a portion of the second container wall 20a employs the micro / nano filter membrane 30 described in the above embodiment. The filter membrane material 32 of the micro / nano filter membrane 30 is located on the side where the collection space 20b is located, and the inner diameter of the filter channels 32a in the second container wall 20a is set to be smaller than the inner diameter of the filter channels 32a in the first container wall 20a. The waste liquid container 40 is fitted outside the collection container 20 to collect the filtrate formed after filtration by the collection container 20.

[0083] Therefore, during the filtration of the sample, micro- and nano-particles with a diameter larger than the inner diameter of the filter pores 32a of the sample container 10 are retained in the sample space 10b, while micro- and nano-particles with a diameter smaller than the inner diameter of the filter pores 32a of the sample container 10 enter the collection space 20b. Simultaneously, the sample in the collection container 20 passes through the micro- and nano-filtration membrane 30 of the collection container 20 under pressure, causing micro- and nano-particles with a diameter larger than the inner diameter of the filter pores 32a of the collection container 20 to be retained in the collection space 20b, while micro- and nano-particles with a diameter smaller than the inner diameter of the filter pores 32a of the collection container 20 enter the waste liquid container 40. This results in the collection container 20 enriching micro- and nano-particles with a diameter between the micro- and nano-filtration membranes 30 of the sample container 10 and the collection container 20, thus obtaining a concentrated sample with a defined particle size using the collection container 20.

[0084] In one embodiment, please refer to Figure 4 The collection container 20 is configured to rotate relative to the waste liquid container 40 around a preset axis, so that the sample in the collection container 20 can flow tangentially parallel to its filter channel 32a, preventing micro- and nano-particles with a diameter larger than the pore size of the filter channel 32a from clogging the filter channel 32a. In a specific implementation, the sample container 10 can also be configured to rotate relative to the collection container 20, and the geometric center lines of the three coincide, which are the rotation axes of the three relative to each other.

[0085] It should be noted that, Figure 4 The bold dashed lines represent the axis of rotation, and the bold solid double arrows represent the direction of rotation of the sample container 10 and / or the collection container 20.

[0086] Please see Figure 6 and combined Figure 1 , Figure 2 and Figure 4The following test of a filtration device with a filtration pore size of 50-130 nanometers provided by an exemplary embodiment shows that the filtration device or micro / nano filtration membrane 30 has very significant filtration performance.

[0087] I. The specific structure of this filtration device is as follows.

[0088] Regarding the sample container 10, the main body of the sample container 10 is a rectangular structure made of plastic material (outline dimensions: length 12 mm, width 12 mm, height 20 mm); a 10 mm * 10 mm square through hole is provided through each of the five walls of the sample container 10 (i.e., the first container wall 10a). A micro-nano filter membrane 30 with a pore size of 130 nanometers is covered on the corresponding square through hole, and a sealant is applied at the contact position to define the sample space 10b, thus obtaining the sample container 10.

[0089] Among them, the micro-nano filter membrane 30 with a pore size of 130 nanometers is mainly a combination structure of a silicon material support substrate 31 and a silicon nitride material filter membrane 32.

[0090] The support substrate 31 has the following approximate dimensions: 10 mm in length, 10 mm in width, and 250 μm in thickness. 100 circular filter windows 31a are arranged in an array through the support substrate 31. The pore size of the filter windows 31a is 100 μm, and the pore spacing between the filter windows 31a is 1000 μm.

[0091] The filter membrane 32 has a thickness of 200 nanometers. 900 filter channels 32b are provided in the area of ​​each filter window 31a of the filter membrane 32. When a silicon dioxide layer is formed on the surface of the filter membrane 32 and the supporting substrate 31 through a high-temperature thermal oxidation process, the pore size (diameter) of the filter channel 32b is 130 nanometers and the pore spacing between the filter channels 32b is 3 micrometers.

[0092] The above-mentioned combined structure was soaked in a mixed solution of concentrated sulfuric acid and hydrogen peroxide with a volume ratio of 2:1 for 2 hours to obtain a micro-nano filter membrane 30 with a pore size of 130 nanometers.

[0093] Regarding the collection container 20, the main body of the collection container 20 adopts a rectangular structure made of plastic material (outline dimensions: length 18 mm, width 18 mm, height 20 mm). A 10 mm * 10 mm square through hole is provided on each of the five walls of the collection container 20 (i.e., the second container wall 20a). A micro-nano filter membrane 30 with a pore size of 50 nanometers is covered on the corresponding square through hole, and the contact position is sealed with adhesive to define the collection space 20b and obtain the collection container 20.

[0094] Among them, the micro-nano filter membrane 30 with a pore size of 50 nanometers is mainly a combination structure of a silicon material support substrate 31 and a silicon nitride material filter membrane 32.

[0095] The support substrate 31 has the following approximate dimensions: 10 mm in length, 10 mm in width, and 250 μm in thickness. 100 circular filter windows 31a are arranged in an array through the support substrate 31. The pore size of the filter windows 31a is 100 μm, and the pore spacing between the filter windows 31a is 1000 μm.

[0096] The filter membrane 32 has a thickness of 200 nanometers. 900 filter channels 32b are provided in the area of ​​each filter window 31a of the filter membrane 32. When a silicon dioxide layer is formed on the surface of the filter membrane 32 and the supporting substrate 31 through a high-temperature thermal oxidation process, the pore size (diameter) of the filter channel 32b is 50 nanometers and the pore spacing between the filter channels 32b is 3 micrometers.

[0097] The above-mentioned combined structure was soaked in a mixed solution of concentrated sulfuric acid and hydrogen peroxide with a volume ratio of 2:1 for 2 hours to obtain a micro-nano filter membrane 30 with a pore size of 50 nanometers.

[0098] As for the waste liquid container 40, the waste liquid container 40 is a rectangular container made of plastic material (outline dimensions: length 24 mm, width 24 mm, height 25 mm).

[0099] The sample container 10 is suspended in the collection container 20, and the combination of the two is suspended in the waste liquid container 40, thus forming a filtration device that can retain particles with a diameter between 50 nanometers and 130 nanometers.

[0100] II. The testing process for this filtration device is as follows.

[0101] 1. After diluting the mixed solution of PS microspheres of 60 nm, 100 nm, 150 nm and 250 nm, add it into sample container 10 as the sample to be filtered; seal the port of sample container 10 with a special connector and connect it to a pressurizing device (e.g., a syringe), and push air into sample container 10 through the pressurizing device so that the sample to be filtered passes through the 130 nm micro-nano filter membrane 30 under pressure and enters collection container 20.

[0102] 2. Using a special connector that can simultaneously seal the ports of the sample container 10 and the collection container 20, connect to the pressurizing device and push in air, so that the sample to be filtered passes through the 50-nanometer micro-nano filter membrane 30 under pressure and enters the waste liquid container 40. In specific implementation, by controlling the air pressure and pressurization time of the pressurizing device, most of the liquid can enter the waste liquid container 40 and obtain a concentrated sample liquid in the collection container 20.

[0103] 3. The particle size distribution of the filtrate collected in collection container 20 is tested using a testing instrument (e.g., a nano-Coulter apparatus) to obtain the following results: Figure 6 The particle size distribution diagram shown is from Figure 6 As can be seen, all particles with a diameter greater than 130 nanometers in the filtrate were filtered out, while particles with a diameter greater than 50 nanometers but less than 130 nanometers were all retained. This shows that the separation and filtration effect of the micro-nano filter membrane 30 with a pore size of 130 nanometers and 50 nanometers is very significant, and the cutoff particle size is very clear.

[0104] 4. During the filtration process, the filter device was rotated at 200 rpm on a rotating instrument. It was observed that the pressurizing device could normally push air into the sample container 10 and / or collection container 20 without increased resistance or difficulty in pushing air in. Furthermore, after the operation was completed, inspection of the micro / nano filter membrane 30 revealed no damage. This indicates that the filter device or micro / nano filter membrane 30 retains sufficient mechanical strength or pressure resistance even after repeated use, and maintains excellent separation performance for micro / nano particles.

[0105] It should be noted that the micro / nano filter membrane 30 provided in this application can also be used independently of the sample container 10 and / or the collection container 20, for example, in the fields of biology, chemistry, and materials, for the separation and filtration of micro / nano particles or for the purification of liquids to remove impurities.

[0106] The above examples illustrate the present invention only to aid in understanding it and are not intended to limit the scope of the invention. Those skilled in the art can make various simple deductions, modifications, or substitutions based on the principles of this invention.

Claims

1. A micro / nano filtration membrane, characterized in that, include: An inorganic material support substrate has a plurality of filter windows disposed through the thickness direction of the micro / nano filter membrane, wherein the length of the filter window in the thickness direction is greater than or equal to 50 micrometers, and the minimum inner diameter of the filter window is greater than or equal to one-third of the length of the filter window. And inorganic material filter membrane, the filter membrane is stacked along the thickness direction and fixed to the support substrate, the filter membrane has filter channels in the area facing each filter window, the filter channels are arranged to penetrate the filter membrane along the thickness direction, the length of the filter channels in the thickness direction is less than or equal to 20 micrometers, and the maximum inner diameter of the filter channels is less than the minimum inner diameter of the filter window. The supporting substrate and the filter membrane form a combined structure, wherein at least the walls of the filter channels in the surface of the combined structure are formed with a hydrophilic material layer; wherein: The material of the filter membrane and / or the material of the supporting substrate is silicon or silicon nitride, and the hydrophilic material layer is a silicon dioxide layer formed on the surface of the combined structure by a high-temperature thermal oxidation process. or The material of the filter membrane and / or the material of the supporting substrate is any one of gallium nitride, boron nitride, molybdenum disulfide and graphene, and the hydrophilic material layer is a silicon dioxide layer formed on the surface of the combined structure by chemical vapor deposition.

2. The micro / nano filtration membrane as described in claim 1, characterized in that, The thickness of the silica layer is set to be less than or equal to 20 nanometers, and / or the hydrophilic contact angle of the silica layer is set to be less than or equal to 45°.

3. The micro / nano filtration membrane as described in claim 1, characterized in that, The filter membrane material has multiple filter channels with the same inner diameter in the area facing each filter window, and the pore size error of the filter channels is less than or equal to ±2 nanometers.

4. The micro / nano filtration membrane as described in claim 1, characterized in that, The filter window is a hole of equal diameter that passes through the support substrate, and the cross-sectional shape of the filter window is circular, elliptical or polygonal. Alternatively, the filter window may be a variable diameter hole that passes through the support substrate, and the inner diameter of the filter window gradually increases from the end of the filter window closer to the filter membrane to the end farther away from the filter membrane, and the cross-sectional shape of the filter window may be circular, elliptical, or polygonal.

5. The micro / nano filtration membrane as described in claim 1, characterized in that, It also includes an inorganic material reinforcing matrix, wherein the supporting matrix is ​​stacked and fixed to the reinforcing matrix along the thickness direction, and the filter membrane is located on the side of the supporting matrix opposite to the reinforcing matrix; wherein: The reinforcing substrate has a plurality of connecting windows that are disposed through the thickness direction. The filter window is located in the area of ​​the supporting substrate and each of the connecting windows, and the maximum inner diameter of the filter window is smaller than the minimum inner diameter of the connecting window.

6. A filtration device, characterized in that, include: A sample container having a first container wall and a sample space defined by the first container wall, the sample space being for accommodating a sample to be filtered, wherein at least a portion of the first container wall is a micro / nano filter membrane as described in any one of claims 1-5, the filter membrane material of the micro / nano filter membrane being located on the side where the sample space is located; and A collection container having a second container wall and a collection space defined by the second container wall, wherein a sample container is inserted into the collection space such that the collection container can collect the filtrate formed after filtration by the sample container.

7. The filtration device as claimed in claim 6, characterized in that, It also includes a waste liquid container; at least a portion of the wall of the second container is made of a micro-nano filtration membrane as described in any one of claims 1-5, wherein the filter material of the micro-nano filtration membrane is located on the side where the collection space is located, and the inner diameter of the filter channel of the second container wall is set to be smaller than the inner diameter of the filter channel of the first container wall. The waste liquid container is placed outside the collection container to collect the filtrate formed after filtration by the collection container.

8. The filtration device as claimed in claim 7, characterized in that, The sample container is configured to rotate relative to the collection container about a preset axis, and / or the collection container is configured to rotate relative to the waste container about a preset axis.

9. A method for preparing the micro / nano filtration membrane as described in claim 1, characterized in that, include: A silicon dioxide layer is formed on the surface of the combined structure using a high-temperature thermal oxidation process; in the combined structure, the materials of the supporting substrate and the filter membrane are either silicon or silicon nitride. The combined structure with a silica layer formed on its surface is placed in a mixed solution of concentrated sulfuric acid and hydrogen peroxide, and after soaking for a preset time, it is taken out to obtain the micro-nano filter membrane. or A silicon dioxide layer is formed on the surface of the composite structure using a chemical vapor deposition process; in the composite structure, the materials of the supporting substrate and the filter membrane are any one of gallium nitride, boron nitride, molybdenum disulfide, and graphene; The combined structure with a silica layer formed on its surface is placed in a mixed solution of concentrated sulfuric acid and hydrogen peroxide, and after soaking for a preset time, it is taken out to obtain the micro-nano filter membrane.

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