CN112915790B

CN112915790B - Ultralow pressure generating device, use method and application

Info

Publication number: CN112915790B
Application number: CN202110182309.7A
Authority: CN
Inventors: 马萧; 冯恩慧
Original assignee: Hangzhou Baimai Medical Technology Co ltd
Current assignee: Hangzhou Baimai Medical Technology Co ltd
Priority date: 2021-02-09
Filing date: 2021-02-09
Publication date: 2021-11-26
Anticipated expiration: 2041-02-09
Also published as: CN112915790A

Abstract

The invention discloses an ultra-low pressure generating device, a using method and application, wherein the ultra-low pressure generating device comprises a filter membrane with low membrane passing resistance, a filter membrane packaging device and a flow guide pipe; the filter membrane packaging device can be used for packaging the filter membrane with low membrane passing resistance to form a sealed filtering space; the draft tube can be used for generating negative pressure to form ultra-low pressure; the ultra low pressure is between 0.01KPa and 40 KPa. The ultra-low pressure generating device can accurately ensure the power stability of the membrane separation system and control the power to be at the ultra-low pressure separation level, and simultaneously effectively enables the whole membrane separation system to solve the technical problem of ultra-low pressure accurate separation of clinical biological samples. The ultra-low pressure generating device can be well applied to the clinical and biological fields, is used for separating blood samples, improves the separation efficiency, shortens the separation time, and does not damage or change the cell state in the separation process.

Description

Ultralow pressure generating device, use method and application

Technical Field

The invention particularly relates to an ultra-low pressure generating device, a using method and application.

Background

From the category of clinical specimen separation methodologies, the main methods for accurate separation are: density gradient centrifugation, microfluidic chip separation, flow cytometry and magnetic bead sorting. From the nature of separation, there are two main types: (1) screening by physical properties (such as density, hardness, size, morphology, etc.), and (2) specific adsorption separation by biochemical properties.

Membrane separation as an integrated separation method can separate target objects by physical or biochemical characteristics. Common membrane separation or membrane filtration fields are divided into methods such as reverse osmosis filtration, nanofiltration, ultrafiltration and microfiltration, and in the biological field, membrane separation methods such as nucleic acid separation by a silicon hydroxyl modified ultrafiltration membrane are available, but the driving pressure is usually at MPa or even above GPa, and although some applications may be in a very low KPa range or even gravity driving, most of the methods are deep filtration methods in the fields of biological medicine and cell workstations, which cannot be precisely controlled.

With the increasing precision of membrane pores, attempts have been made to separate biological or clinical samples, including circulating tumor cells, by using a nuclear pore membrane and a micro-machined membrane, but from the design of the existing documents and methods, it can be found that in order to improve the precision, the problems of reducing the pore diameter to ensure accurate separation, simultaneously ensuring the loss of a trace amount of rare target samples, increasing the resistance caused by reducing the pore diameter, and the like, can be overcome only by increasing the pressure of the membrane, and since the cell itself is a non-rigid sphere, the physical properties of the cell subpopulation in a natural state are lost even the cell itself is damaged due to the excessive pressure pressing the cell, the existing membrane separation method is difficult to provide a perfect solution for accurate separation of clinical samples.

In addition, the pore size of a filtration membrane is generally inversely proportional to the porosity, and in particular, in a microporous membrane, the porosity is conversely smaller as the pore size is larger. However, in general, microporous membranes such as chemical membranes or nuclear pore membranes have to reduce the porosity of the membrane by increasing the pore size of the membrane due to the limitations of support strength and pore size precision, so the actual macro-filtration efficiency of the fluid passing through the membrane may be reduced, various adsorption effects and non-specific interception may be increased, and the final benefit of separating clinical or biological samples through the ultra-low pressure membrane may not be increased. Therefore, the existing membrane separation system cannot perform efficient and nondestructive separation of cell subsets with high precision and with certain size or rigidity characteristics.

In addition, the existing membrane separation technology generally needs larger excess membrane pressure to ensure the filtration flux, and the conventional microfiltration or ultrafiltration is generally carried out under the pressure above MPa, so that a sample can ensure a certain filtration speed and a stable membrane scale layer. The transmembrane resistance considered by the conventional filtration is from two parts, one part is the resistance of the membrane pore material, the other part is the resistance of the membrane layer on the membrane to the sample after the membrane layer is stabilized, and if a larger pressure is needed to overcome the resistance of the membrane, the resistance of the membrane layer is larger because the membrane layer formed under the larger pressure is also tighter, which is why most of the conventional filtration is designed under the larger transmembrane pressure.

Disclosure of Invention

In view of the above situation, the present invention provides an ultra-low pressure generating device, a use method and an application thereof, in order to overcome the defects of the prior art.

In order to achieve the purpose, the invention provides the following technical scheme:

an ultra-low pressure generating device comprises a filter membrane with low membrane passing resistance, a filter membrane packaging device and a flow guide pipe; the filter membrane packaging device can be used for packaging the filter membrane with low membrane passing resistance to form a sealed filtering space; the draft tube can be used for generating negative pressure to form ultra-low pressure; the ultra low pressure is between 0.01KPa and 40 KPa.

Further, the self-resistance of the filter membrane with low transmembrane resistance is not more than 1.5 KPa.

Further, the filter membrane with low membrane passing resistance is any one of a parylene microporous filter membrane, a polyimide microporous filter membrane, a polycarbonate microporous filter membrane and a polyether sulfone filter membrane.

Furthermore, the filter membrane packaging device comprises a first fixing piece and a second fixing piece, and the first fixing piece and the second fixing piece are detachably connected.

Further, the first fixture includes a first cavity configured to be usable for storing a sample to be filtered.

Furthermore, the honeycomb duct is directly connected with the second fixing piece, or the second fixing piece is connected with the transition structure, and the transition structure is connected with the honeycomb duct.

Further, the transition structure is at least one of a sinking platform structure, a conical structure and a cylindrical structure.

Furthermore, a flow deflector is arranged in the conical structure or a flow deflector is arranged in the tubular structure.

Use of an ultra-low pressure generating device for separating a biological sample, said device being as described above.

A method for using an ultra-low pressure generating device, which is the above device, comprising the steps of:

(1) placing the filter membrane between the first fixing piece and the second fixing piece;

(2) connecting and fixing the first fixing piece and the second fixing piece;

(3) connecting the guide pipe with the second fixing piece; if the guide pipe and the second fixing piece are fixedly connected together or the guide pipe and the second fixing piece are integrally formed, directly skipping the step and carrying out the next step;

(4) adding low surface tension liquid to soak the filter membrane into the first cavity, then adding liquid A, wherein the liquid A is pure water or other liquid with different densities, the liquid A in the first cavity enters the lower part of the membrane, the liquid on the membrane keeps the membrane in a soaking state, the liquid A continuously enters the flow guide pipe, and finally a liquid column with stable height appears in the flow guide pipe to form negative pressure with certain size.

The invention has the beneficial effects that:

(1) the ultra-low pressure generating device can accurately ensure the power stability of the membrane separation system and control the power to be at the ultra-low pressure separation level, and simultaneously effectively enables the whole membrane separation system to solve the technical problem of ultra-low pressure accurate separation of clinical biological samples.

(2) The ultra-low pressure generating device can be well applied to the clinical and biological fields, can be used for separating blood samples, improves the separation efficiency, shortens the separation time, and does not damage or change the cell state in the separation process. Compared with the traditional normal-pressure membrane separation device, the invention can obtain more information of multiple dimensions of target objects and background cells, and can carry out high-precision effective nondestructive separation on cell subsets with certain size or rigidity characteristics.

Drawings

Fig. 1 is a schematic structural diagram of a first fixing member in embodiment 2.

FIG. 2 is a schematic view showing the structure of the first fixing member (showing the structure of the first chamber) in example 2.

Fig. 3 is a schematic structural view of the first fixing member in example 2 (showing the structure of the base).

Fig. 4 is a schematic structural view of a second fixing member in embodiment 2.

Fig. 5 is a plan view of the second fixing member in embodiment 2.

Fig. 6 is a schematic structural view of the first fixing member in embodiment 3.

Fig. 7 is a schematic structural view of a second fixing member in embodiment 4.

Fig. 8 is a schematic view of the first fastener piece in combination with the second fastener piece.

Figure 9 is a cross-sectional view of figure 8 (showing the elastomeric seal and the microfiltration membrane L).

Fig. 10 is a schematic view of the transition structure and the draft tube combined together (wherein the vertical heights of the three sections i, ii and iii are respectively 15mm, 10mm and 20mm, and the inner diameter of the outlet of the draft tube is 3 mm).

Fig. 11 is a schematic diagram of a transition structure combined with a draft tube (wherein the vertical heights of the three sections i, ii and iii are respectively 15mm, 10mm and 20mm, and the inner diameter of the outlet of the draft tube is 1.5 mm).

Fig. 12 is a schematic diagram of a transition structure combined with a draft tube (wherein the vertical heights of the three sections i, ii and iii are respectively 15mm, 10mm and 10mm, and the inner diameter of the outlet of the draft tube is 3 mm).

Fig. 13 is a schematic diagram of the transition structure and the draft tube combined together (wherein the vertical heights of the three sections i, ii and iii are respectively 15mm, 1mm and 20mm, and the inner diameter of the outlet of the draft tube is 3 mm).

FIG. 14 is a schematic view of the transition structure combined with the draft tube (the transition structure and the draft tube are combined into one, the total vertical height of the draft tube is 35mm, the draft tube is gradually narrowed, and the inner diameter of the outlet of the draft tube is 4 mm).

FIG. 15 is a schematic view of the transition structure combined with the draft tube (the transition structure and the draft tube are combined into one, the total vertical height of the draft tube is 17mm, the draft tube is gradually narrowed, and the inner diameter of the outlet of the draft tube is 4 mm).

Detailed Description

In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described and illustrated below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments provided in the present application without any inventive step are within the scope of protection of the present application.

Reference in the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the specification. The appearances of the phrase in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of ordinary skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments without conflict.

Unless defined otherwise, technical or scientific terms referred to herein shall have the ordinary meaning as understood by those of ordinary skill in the art to which this application belongs. Reference to "a," "an," "the," and similar words throughout this application are not to be construed as limiting in number, and may refer to the singular or the plural. The present application is directed to the use of the terms "including," "comprising," "having," and any variations thereof, which are intended to cover non-exclusive inclusions; reference to "connected," "coupled," and the like in this application is not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Reference herein to "a plurality" means greater than or equal to two. "and/or" describes an association relationship of associated objects, meaning that three relationships may exist, for example, "A and/or B" may mean: a exists alone, A and B exist simultaneously, and B exists alone. Reference herein to the terms "first," "second," "third," and the like, are merely to distinguish similar objects and do not denote a particular ordering for the objects.

Example 1

An ultra-low pressure generating device comprises a filter membrane with low membrane passing resistance, a filter membrane packaging device and a flow guide pipe; the filter membrane is positioned between the packaging devices, and the guide pipe 15 is connected with the packaging devices. The microporous filter membrane with low membrane passing resistance can be used for separating a sample to be filtered; the filter membrane packaging device can be used for fixing and packaging the filter membrane with low membrane passing resistance to form a sealed filtering space, so that the outflow of a sample is avoided. The draft tube can be used for generating negative pressure to form ultra-low pressure.

The ultra low pressure generating device can be used for providing the required ultra low pressure in the filtering process, and the ultra low pressure is between 0.01KPa and 40 KPa.

In some preferred modes, the self-resistance of the filter membrane with low transmembrane resistance is not more than 1.5 KPa. The low-transmembrane-resistance filter membrane may be a parylene microporous filter membrane, a polyimide microporous filter membrane, a polycarbonate microporous filter membrane, a polyethersulfone filter membrane, or the like. The low transmembrane resistance filter can be used for separating a sample to be filtered, which may be a biological sample, such as a blood sample or a cell enrichment or separation in a clinical sample (e.g., urine, various types of lavage fluids, etc.).

In some preferred forms, the filter membrane sealing device includes a first fixing member and a second fixing member, the first fixing member and the second fixing member are detachably connected, for example, by a screw thread, a snap connection, or the like, and the snap connection facilitates installation and fixation of the sealing device and disassembly of the sealing device to separate the first fixing member from the second fixing member. In some preferred modes, a threaded hole is formed in the first fixing piece, a threaded hole is formed in the second fixing piece, the first fixing piece and the second fixing piece can be fixedly connected through a screw or a bolt, in other embodiments, a buckle is formed in the first fixing piece, a clamping groove is formed in the second fixing piece, and the first fixing piece and the second fixing piece can be fixedly connected through the matching of the buckle and the clamping groove.

In some preferred modes, the filter membrane is positioned between the first fixing member and the second fixing member, and after the first fixing member and the second fixing member are connected and fixed, the filter membrane is fixed to form a sealed filtering space for filtering the sample solution.

In some preferred modes, the filter membrane packaging device further comprises a sealing element 3, the sealing element 3 is an elastic sealing element 3, the elastic sealing element 3 is located between the first fixing element and the second fixing element, the elastic sealing element 3 is configured to be capable of sealing the device, when the filtering is avoided, a sample to be filtered flows out laterally, the elastic sealing element has elasticity and can deform, and when the elastic sealing element is in contact with the microporous filter membrane, the microporous filter membrane cannot be punctured or damaged, so that the smoothness of the surface of the microporous filter membrane is guaranteed. In some preferred modes, the sealing element can be an elastic sealing ring, and can also be other substances with elasticity, such as soft glue and the like.

In some preferred forms, the first mount includes a first cavity configured to be used to store a sample to be filtered. The first chamber 4 has a first inlet 5 and a first outlet 6, and a sample to be filtered can enter the first chamber 4 through the first inlet 5 and exit the first chamber through the first outlet 6. In other embodiments, the first fixture may not include the first lumen 4, and the shape of the first lumen is not limited by the present invention. The first cavity may be cylindrical, rectangular parallelepiped, square, conical, etc.

In some preferred modes, the second fixing member 2 is provided with a placing area 16 for placing the microporous filter membrane, and the placing area 16 has a flat surface, and the bottom surface of the microporous filter membrane can be completely attached to the placing area.

In some preferred modes, as shown in fig. 4, the second fixing member 2 is further provided with a third through hole 17, the third through hole 17 is located inside the placing area 16, and the third through hole 17 facilitates the outflow of the filtrate.

In some preferred forms, the duct 15 is directly connected to the second fixed part, either detachably or fixedly (or integrally). In other embodiments, the second mount is coupled to a transition structure that is coupled to the draft tube 15. Generally, the working area of the filter membrane is large, while the cross-sectional area of the flow conduit is generally small, so that a transition structure connection is required. In other embodiments, a transition structure is provided in the draft tube 15.

In some preferred manners, the duct 15 and the transition structure may be fixedly connected (e.g., integrally formed or otherwise fixedly connected) or detachably connected. In some preferred manners, the draft tube 15 may have a cylindrical shape, a square cylindrical shape, a conical shape, or other shapes, and the shape of the draft tube 15 is not particularly limited in the present invention. The draft tubes 15 of different diameters generate different resistances, but do not affect the magnitude of the generated negative pressure, and affect whether the ultra-low pressure generator is stable.

In some preferred forms, the transition structure is a sunken platform structure 40, as shown in fig. 7, and in other embodiments, the transition structure may be a tapered structure without a platform, as shown in fig. 4. In other preferred forms, the transition structure includes a conical structure and a sink deck structure 40. The transition structure may have other shapes, and the present invention is not limited to the specific structure of the transition structure. In the present invention, the sinking platform structure may be cylindrical, trapezoidal or other shapes, and the present invention does not limit the specific structure of the sinking platform.

The transition structure is provided because the working area of the filter membrane is large, while the cross-sectional area of the flow conduit 15 is usually small. The transition structure has another function of providing proper resistance in the process of generating the negative pressure liquid column below the filter membrane, for example, when the transition structure is a conical structure, the resistance is small, and the liquid can easily slide down into the flow guide pipe 15, so that the final stable liquid column is shorter than the liquid column formed in the state of large resistance.

In some preferred forms, baffles 24 are provided within the transition structure. The number of baffles is at least one and the liquid can be filtered by percolation at very low pressures. The guide vanes 24 may be expanded in a centrosymmetric fashion into 3 or 6 guide vanes.

In other embodiments, the transition structure may be a structure with other shapes, and the invention does not limit the specific shape of the transition structure.

The use method of the ultra-low pressure generating device comprises the following steps:

(2) connecting and fixing the first fixing piece and the second fixing piece;

(3) connecting the draft tube 15 with the second fixed member; the draft tube 15 is detachably connected to the second fixing member, so that the length of the draft tube 15 can be changed to generate different liquid column pressures. If a transition structure is arranged between the guide pipe and the second fixing piece, the second fixing piece can be connected with the transition structure firstly, and then the transition structure is connected with the guide pipe.

If the transition structure exists and is positioned between the second fixing piece and the flow guide pipe, the second fixing piece, the flow guide pipe and the flow guide pipe are connected and fixed. If transition structure and honeycomb duct integrated into one piece or fixed connection, perhaps transition structure and second mounting integrated into one piece or fixed connection, then only need with second mounting with honeycomb duct connection fixed can.

If the draft tube 15 and the second fixed member are fixedly connected together or the two are integrally formed, directly skipping the step and carrying out the next step;

(4) firstly, a filter membrane is soaked, low surface tension liquid (such as alcohol, PEG aqueous solution (molecular weight is below 4000) with concentration of below 5% w/v, isopropanol and the like is adopted, the surface tension of the membrane can be changed, the liquid can conveniently pass through, then liquid A (the liquid A is pure water or other liquids with different densities, such as glycerol, heavy water, mercury liquid and the like, but toxic reagents such as heavy water, mercury liquid and the like can only be used in a fume hood operation environment) is added into a first cavity, the liquid A in the first cavity enters the lower part of the membrane through osmosis, and as long as the liquid on the membrane keeps the membrane in a soaking state, the liquid A can continuously enter a draft tube 15 to form a liquid column.

The export of honeycomb duct lower extreme is arranged in the air, and the pipe diameter of honeycomb duct 15 is less than the export bore of first chamber, and when the speed that liquid flows out honeycomb duct 15 was less than the speed that liquid permeates membrane inflow honeycomb duct 15 in the first chamber, one section space in honeycomb duct 15 can be filled up very fast, appears the liquid column of steady height in the honeycomb duct 15, and honeycomb duct 15 forms the negative pressure of certain size this moment. The negative pressure can be tested by external equipment, but in actual use, the negative pressure does not need to be measured in real time.

After the liquid A enters the flow guide pipe 15 and the liquid A on the filter membrane flows out, the liquid column in the flow guide pipe 15 can automatically stop in a balanced state (the liquid column in the flow guide pipe 15 can not completely disappear) under the action of the surface tension of the filter membrane, and the ultra-low pressure generating device is arranged and finished, so that stable driving pressure can be provided for the subsequent filtration process. When the flow guide tube 15 is directly connected with the second fixing piece (the transition structure is positioned inside the flow guide tube 15), when liquid is more than the internal volume of the flow guide tube 15, the liquid naturally flows away, and the vertical length of the flow guide tube 15 is the vertical height of the liquid column.

When the liquid on the filter membrane completely flows, the residual liquid on the membrane surface stops flowing under the action of surface tension, the originally flowing liquid under the membrane also stops flowing, and the liquid column standing at the moment forms a negative pressure source under the membrane.

After the liquid to be filtered is poured, whether the liquid on the membrane passes through the membrane hole or not is mainly determined by whether negative pressure larger than membrane passing resistance exists below the membrane; if negative pressure greater than the membrane passing resistance exists, liquid can pass through the membrane holes, and liquid in the liquid column flows out, so that the liquid column is finally balanced at a certain height, and the liquid column at the certain height is required as power for the filtering process.

The pressure in the filtering process can be adjusted by adjusting the length of the draft tube 15 below the membrane. In specific implementation, the pressure in the filtering process can be adjusted by replacing the draft tube 15 with different lengths, and certainly, a certain device can be adopted for automatic adjustment.

The flowing speed of the membrane passing liquid in the filtering process does not change the height of the liquid column, the flowing speed of the membrane passing liquid is slow, and the dripping of the lower liquid column from the port is slow, so the pressure is kept at the pressure of the initially formed liquid column.

In the present invention, the initial filtration membrane resistance R₁Is the self resistance R of the filter membrane after infiltration₀Then R is required₀Less than 15 drag R of the draft tube₂Therefore, under the driving of gravity, the liquid flowing into the draft tube 15 is larger than the liquid flowing out of the draft tube 15, and the liquid column in the draft tube 15 can spontaneously generate negative pressure. The resistance of the flow guide tube 15 includes the resistance of the wall of the flow guide tube 15 to the fluid and the tension of the liquid at the orifice of the flow guide tube 15 when the liquid drops.

The device worksThe core of the method is that the membrane passing resistance R under the filtration membrane infiltration state is utilized₁The pressure is far less than the pressure P2 required by the surface tension caused by overcoming the interface after the liquid on the filter membrane completely flows out, so that the membrane passing resistance is only required to be overcome in the process of forming a liquid column in the guide pipe 15 below the filter membrane and in the process of flowing the filtered liquid during normal work, the flowing process meets the siphon principle and the Bernoulli equation, and the 'negative pressure' theoretically calculated below the filter membrane exists, which is the negative pressure generated by the ultra-low pressure generating device.

Example 2, see figures 1-5.

Specifically, in the present embodiment, as shown in fig. 1 to 5, the sealing device includes a first fixing member 1, a second fixing member 2 and a sealing member 3, wherein the first fixing member 1 and the second fixing member 2 are configured to be capable of cooperating to fix and seal the microporous filter membrane; sealing member 3 is elastic sealing member 3, and elastic sealing member 3 is located between first mounting and the second mounting, and elastic sealing member 3 is configured to can sealing device, when avoiding filtering, treats filterable sample side direction outflow, and in addition, elastic sealing member has elasticity, can take place deformation, and when elastic sealing member and microfiltration membrane contact, can not stab or harm the microfiltration membrane, is favorable to guaranteeing the planarization on microfiltration membrane surface. In some preferred modes, the sealing element can be an elastic sealing ring, and can also be other substances with elasticity, such as soft glue and the like.

In some preferred modes, the first fixing element 1 and the second fixing element 2 can be detachably connected, so that the packaging device is convenient to install or open.

In some preferred forms, as shown in fig. 1, the first fixing member 1 comprises a first cavity 4 configured to be able to be used for storing a sample to be filtered. The first chamber 4 has a first inlet 5 and a first outlet 6, and a sample to be filtered can enter the first chamber 4 through the first inlet 5 and exit the first chamber through the first outlet 6. In other embodiments, the first fixture may not include the first lumen 4, and the shape of the first lumen is not limited by the present invention.

In some preferred forms, as shown in fig. 1-2, the first fixing member 1 further comprises a base 7, which is connected to the second fixing member by snap-fitting. The base 7 and the first chamber 4 may be fixedly connected or detachably connected. In this embodiment, the base is fixedly connected to the first chamber.

In some preferred modes, a through hole or a clamping groove is formed in the base and used for being combined with the second fixing piece; in another preferred mode, a fixture block is arranged on the base, and the fixture block is configured to be capable of being combined with the second fixing piece. In this embodiment, as shown in fig. 1, a first through hole 8 is formed on the base 7 for being connected with the second fixing member 2 in a matching manner. The first through hole 8 may be square, circular or other suitable shape. In some preferred modes, the base 7 is uniformly provided with at least one first through hole, so that the first fixing member 1 and the second fixing member 2 are matched tightly, and the binding force or the acting force is uniform, thereby being beneficial to packaging the filter membrane. In this embodiment, as shown in fig. 1, two first through holes 8 are provided on the base 7 at opposite positions.

In some preferred modes, the bottom surface of the base is provided with a groove for assembling the elastic sealing element, the space in the groove is larger than the volume of the elastic sealing element, so that the elastic sealing element is favorably placed in the groove, and after the elastic sealing element is placed in the groove, a reserved space is reserved, and when the elastic sealing element is compressed, the elastic sealing element deforms and can occupy the reserved space. In some preferred modes, the space on the base except the groove can be used for arranging other functional units.

In some preferred modes, as shown in fig. 3, the bottom surface of the base 7 is provided with an inward concave pit 9, a second through hole 10 is arranged in the middle of the pit 9, and the second through hole 10 is communicated with the first outlet 6. A downwardly convex support 11 is disposed around the second through hole 10, and the support may be square, circular, triangular, other polygonal or irregular shape or other suitable shape. In some preferred forms, the number of the supporting members is at least two. In some preferred manners, the supporting member 11 is a circular supporting member 11, which is beneficial to uniformly bear the force, in this embodiment, as shown in fig. 3, the supporting member includes two circular supporting members 11, the two circular supporting members 11 have the same circle center, a groove 12 is formed between the two circular supporting members 11, and may be used for placing an elastic sealing member, and the elastic sealing member may be an elastic sealing ring. In other preferred modes, the bottom surface of the base is a flat surface, the bottom surface is provided with a groove for assembling the elastic sealing element, but no supporting piece exists; the shape of the groove can be square, round, arc or annular, etc.

In some preferred modes, as shown in fig. 3, a protrusion 13 facing the second through hole 10 is arranged at the inner edge of the concave pit 9, and the protrusion 13 can be used for being matched and encapsulated with the second fixing piece 2.

In some preferred forms, as shown in figures 4-5, the second fixing 2 comprises a seat 14, the seat 14 being configured to be able to engage with the first fixing. In some preferred forms, the support 14 is provided with a placement area 16 for placing the microporous filter membrane, and the placement area 16 has a flat surface, and the bottom surface of the microporous filter membrane can be completely attached to the flat surface.

In some preferred modes, as shown in fig. 4, the support 14 is provided with a third through hole 17, the third through hole 17 is positioned inside the placing area 16, and the third through hole 17 facilitates the outflow of the filtrate.

In some preferred manners, a fixture block 18 is arranged on the support 14 at a position corresponding to the first through hole 8, and the fixture block 18 is configured to be capable of being matched and clamped with the first through hole 8 on the first fixing member 1, so as to realize the combination of the first fixing member 1 and the second fixing member 2. In other preferred modes, the support is provided with a through hole or a clamping groove for being combined with the clamping block on the first fixing piece.

In some preferred modes, the fixture block 18 comprises an inclined transition surface 19, so that the fixture block 18 is combined with the clamping groove or the through hole conveniently, and the fixture block 18 is not easy to separate after entering the clamping groove or the through hole, so that the combination is firm, and the filter membrane is convenient to encapsulate.

In some preferred manners, as shown in fig. 4, the support 14 is provided with a fourth through hole 32, the fixture block 18 is located in the fourth through hole 32, the inner side of the fixture block 18 is fixedly connected with the support, and the outer side of the fixture block 18 is not connected with the support, so that the connection between the fixture block 18 and the support is reduced, and when the fixture block 18 is stressed and deformed (because when the fixture block 18 is stressed, the fixture block 18 transmits the force to the filter membrane placing area plane), the stress on the placing area plane can be reduced, and the deformation of the placing area plane can be reduced. The fourth through hole 32 can adjust the stress distribution on the plane of the placing area due to the deformation of the fixture block 18, and is also beneficial to opening the mold and injection molding of the fixture block 18.

The space on the second fixing member except the third through hole 17, the microfiltration membrane placing region 16, the fixture block 18, the fourth through hole 32 and the like can be used for designing other functional units.

In some preferred embodiments, as shown in FIG. 4, the holder 14 is further provided with a strip 20, and the strip 20 can be used for limiting the position of the microporous membrane. In some preferred modes, the clamping strip 20 is not connected with the clamping block 18; avoid the fixture block 18 to transmit more power to the microporous filter membrane and place the district, cause the microporous filter membrane to deform. In some preferred modes, the inner side of the clamping strip 20 is provided with an arc-shaped surface 21, so that the microporous filter membrane is convenient to take and place.

The addition of the clamping strip 20 or similar structure or other shaped or oriented rib on the support 14 may be a structure as shown in fig. 7, which, in cooperation with the elastic sealing element (the size of the elastic sealing element may be selected accordingly), can change the pre-stress received in the second fixing element, and this structure (the clamping strip 20 or similar structure or rib, etc.) can enhance the strength of the plane of the filter membrane placing area 16, and does not enhance the connection strength of the clamping block 18 and the plane of the placing area 16, so that the deformation of the clamping block 18 will cause less deformation of the plane of the placing area, and the pressure transmitted by the clamping block 18 to the plane may also be reduced, which requires adjusting the size and elasticity of the elastic sealing element, and satisfies that the pre-stress formed by the force transmitted by the clamping structure to the plane and the acting force transmitted by the elastic sealing element can be greater than the external interference force, thereby ensuring that the deformation of the filter membrane caused by the deformation of the plane of the placing area 16 is smaller than the maximum acceptable range, while stably ensuring the sealing performance of the device.

In some preferred forms, the support 14 is provided with a platform 22, said platform 22 being able to engage with the pit 9. In some preferred forms, the platform 22 is provided with a recess 23, and the recess 23 is configured to be able to engage with the protrusion 13 of the first fixing member 1.

In some preferred modes, the draft tube 15 is fixedly connected with the second fixing member 2, as shown in fig. 4, the draft tube 15 is integrated with the transition structure, the shape of the draft tube 15 is a conical structure, the diameter of the upper opening of the draft tube 15 is larger, and the diameter of the lower opening of the draft tube 15 is smaller.

In some preferred forms, the flow-guide tube 15 is internally provided with flow-guide vanes 24 which allow to conduct the liquid to be filtered by means of percolation at very low pressures. In some preferred manners, the number of the guide vanes 24 may be one, or may be two or more (i.e., a plurality of). The plurality of guide vanes may be arranged in a centrosymmetric manner. In this embodiment, as shown in fig. 4, there is one flow deflector.

The use method of the filter membrane packaging device comprises the following steps:

(1) placing the filter membrane on the placing area 16 on the second fixing piece 2, and enabling the bottom surface of the filter membrane to be attached to the surface of the placing area 16;

(2) with first mounting 1 and the 2 lock of second mounting, after first mounting combines with the second mounting, the elastic sealing spare atress in the recess is compressed, realizes sealed, and the sample can not the lateral flow.

The elastic sealing element in the groove deforms, and the elastic sealing element preferentially deforms towards the left side and the right side to occupy reserved space in the groove (after the first fixing element and the second fixing element are combined, the elastic sealing element can hardly move in the vertical direction).

In this embodiment, the first fixing member 1 and the second fixing member 2 are fastened, after the first fixing member is combined with the second fixing member, the clamping block 18 on the second fixing member is clamped and combined with the first through hole 8 on the first fixing member 1, and since the height of the elastic sealing member is greater than that of the supporting member 11, the elastic sealing member is compressed after contacting with the upper surface of the filter membrane. Because there is the headspace in the recess 12, in the headspace in elastic sealing member can be compressed to recess 12 preferentially, the contact surface of elastic sealing member and filter membrane received the pressure of perpendicular to filter membrane, like this sealed while, can not cause tangential or inhomogeneous pulling force to the filter membrane, can guarantee the level and smooth of membrane. Elastic sealing member and filter membrane in close contact with, just so enclose a sealed membrane filtration space in the city, during filtration process, the sample can not the lateral flow.

In this embodiment, after first mounting 1 and the 2 lock of second mounting, elastic sealing element 3 is compressed and is provided the sealing pressure behind the contact membrane, elastic sealing element 3 is compressed and is withdrawn the one side that the sealing element contacted the membrane and is no longer than the reference surface (the reference surface is the contact surface of support piece and filter membrane, elastic sealing element and buckle structure stress balance form prestressing force, guarantee sealed effect), elastic sealing element 3 warp the headspace in the filling groove, the planarization of sealed reference surface is guaranteed on the one hand to this function, on the other hand can play the effect of adjusting machining error, in the device assembling process, even the membrane surface that elastic sealing element 3 contacted is not a plane even atress simultaneously, thereby also can guarantee that the membrane can not locally receive very big pressure uneven atress that leads to the membrane surface to drag and the unevenness. Under the system, the filter membrane can meet the requirement of flatness and can ensure the sealing requirement.

In some preferred modes, the material used for the first fixing element and the second fixing element is polyphenylene sulfone resin (PPSU), Polystyrene (PS), Polycarbonate (PC) or other materials with similar hardness, and the material of the first fixing element and the second fixing element is not specifically limited.

Other embodiments in this embodiment may be the same as embodiment 1.

Example 3 referring to figures 6 and 8.

In this embodiment, as shown in fig. 6, the first fixing member includes a first cavity 4 and a base, and the shape of the first cavity is similar to a cone. In other embodiments, the shape of the first cavity 4 may be a rectangular parallelepiped shape, a square shape, a cylindrical shape, or other shapes, and the invention is not limited to the specific shape of the first cavity. The size and shape of the first chamber 4 does not affect the magnitude of the negative pressure below the membrane, but the height of the liquid to be filtered above the membrane is not too high, otherwise a non-negligible positive pressure is created.

In some preferred forms, the upper section of the first chamber 4 is provided with mounting sites for mounting respective covers. The mounting portion may be an outwardly protruding rib or an inwardly recessed groove or a threaded or snap-fit structure, or may be other suitable structures for mounting a corresponding cover. In this embodiment, as shown in fig. 6 and 8, the first chamber 4 is provided with an outwardly protruding rib 30 on the outside thereof for engaging with the cover.

In some preferred manners, as shown in fig. 8, the side surface of the first cavity 4 is provided with an abdicating structure 33, which can be used for abdicating the fixture block without affecting the combination of the fixture block and the first through hole. When the packaging device needs to be installed or disassembled, the clamping block can be extruded towards the middle, the clamping block is guaranteed not to contact the first cavity, and the phenomenon that the first cavity is damaged by extrusion force caused by the first cavity is avoided.

Other embodiments in this embodiment may be the same as or similar to embodiment 2 (the second fixing member in this embodiment may be the structure in embodiment 2 or similar to the structure in embodiment 2).

Example 4 reference is made to figures 7 to 9.

In this embodiment, the second fixing member 2 includes a seat 14, and the seat 14 is configured to be able to be combined with the first fixing member. In some preferred modes, as shown in fig. 7, a fixture block 18 is connected to the support 14, and a reinforcing rib (which may be in the form of a fixture strip 20 or in a form similar to the fixture strip 20) is further provided on the support 14, and the reinforcing rib is not connected to the fixture block; the strengthening rib not only can carry on spacingly when laying microporous membrane, can strengthen the filter membrane moreover and place 16 planar intensity in district, because the strengthening rib does not be connected with the fixture block, so do not strengthen the fixture block and place 16 planar joint strength in district, so the deformation of fixture block can be still less the cause place the district plane and warp. In this embodiment, as shown in fig. 7, the plurality of ribs enclose a cavity 31 having a certain shape, which may be a cavity having a certain functionality and may be used to store a pre-loaded reagent; the pre-loaded reagent can be lysate which plays a role in cracking cells on the membrane, and can also be a diluent and the like.

Other embodiments in this embodiment may be the same as or similar to embodiment 2, and the first fixing member in this embodiment may be the structure in embodiment 2 or the structure in similar embodiment 2.

The first fixing member in this embodiment may also be the structure in embodiment 3 or a structure similar to that in embodiment 3.

Example 5

In this embodiment, as shown in fig. 10, the transition structure is a combination of a cylindrical structure and a tapered structure, and the flow guide pipe is a pipe having a uniform inner diameter.

Example 6

In this embodiment, as shown in fig. 14, the transition structure is a combination of two conical structures, and the flow guide pipe is a pipe with a gradually decreasing inner diameter.

Example 7 Filter Effect identification

In this example, the ultra low pressure generating apparatus described in example 4 was used, and as shown in fig. 9, the transition structure was a sinking platform 40. The method for using the ultra-low pressure generator is adopted.

(1) placing the filter membrane L between the first fixing piece and the second fixing piece;

(2) connecting and fixing the first fixing piece and the second fixing piece;

(3) connecting the draft tube 15 with the second fixed member; in this embodiment, the transition structure of the duct 15 and the second fixing member are fixedly connected together or integrally formed, and this step is skipped directly to perform the next step;

(4) 1mL of ethanol is added to soak the filter membrane L to change the surface tension of the membrane and facilitate the liquid to pass through, 2mL of pure water is added, the pure water in the first cavity forms a liquid column of about 2cm on the membrane, and the liquid is forced to enter the draft tube 15 through the filter membrane L.

In some preferred modes, the pure water is added at one time, and the continuous flow is stable, so that a desired liquid column is easier to form and a designed negative pressure value is generated. The volume of the added pure water is preferably greater than the sum of the internal volume of the flow-guide tube and the internal volume of the transition structure, so that a liquid column of a desired height is relatively easily formed.

The diameter of the flow guide tube 15 is smaller than the diameter of the outlet of the first chamber, the speed of the liquid flowing out of the flow guide tube 15 is smaller than the speed of the liquid in the first chamber flowing into the flow guide tube 15 through the filter membrane, and a section of space in the flow guide tube 15 will be filled up quickly, in this embodiment, the height of the last stable liquid column in the flow guide tube 15 is about 5cm, and at this time, the flow guide tube 15 forms a negative pressure of about 0.5KPa (according to the siphon principle, the pressure difference can be obtained from the height difference, or a detection device can be used to detect the negative pressure value).

After 2mL of pretreatment liquid (pure water) enters the flow guide pipe 15 and the liquid on the filter membrane flows out, the liquid column in the flow guide pipe 15 can be automatically stopped in a balanced state under the action of the surface tension of the filter membrane, the ultra-low pressure generating device is set to be finished at the moment, the negative pressure is kept at 0.5KPa, and stable driving pressure can be provided for the subsequent filtration process.

In this example, the sink platform was 14mm in diameter and 3mm in height, the filter membrane used was a parylene microporous filter membrane with a circular working area of 14mm in diameter, 11 μm in thickness and 60% porosity, the flow guide tube material was a plain polycarbonate smooth surface injection molded part without additional surface treatment, 58mm in length and 4mm in internal diameter of the spout of the liquid outlet.

The system can finally keep the system working at the ultralow pressure of 0.5KPa, and the time for separating 3mL of healthy human whole blood sample is 45 seconds.

Example 8 Filter Effect evaluation

In this example, the ultra low pressure generating apparatus described in example 2 was used, as shown in FIGS. 3 to 4. The method for using the ultra-low pressure generator is adopted.

In this embodiment, the microporous filter membrane used is a polyimide microporous filter membrane with a circular working area diameter of 49mm, a thickness of 10 μm and a porosity of 30%, the material of the flow guide tube 15 is a polyphenylene sulfone resin smooth surface injection molding without additional surface treatment, the vertical length is 150mm, the diameter of the inlet of the flow guide tube is 49mm, and the diameter of the orifice of the liquid outlet is 1.5 mm. In fig. 4, the draft tube 15 and the transition structure (the transition structure is a tapered structure) are integrated.

2mL of alcohol is firstly added to infiltrate the filter membrane, then 6mL of pure water is poured in, so that a stable negative pressure is generated by the ultra-low pressure generator, and then 5mL of whole blood sample is directly poured into the first cavity, and the pressure generated by 5mL of whole blood on the membrane is not large due to the large first cavity, so that the negative pressure below the membrane mainly plays a leading driving role. The system can finally keep the system working at an ultra-low pressure of 1.4KPa, and the time for separating 5mL of whole blood sample of a healthy person is 180 seconds.

Example 9 Filter Effect identification

In this example, the ultra-low pressure generator described in example 2 was used, and the guide pipe 15 was made of polystyrene and subjected to hydroxylation treatment as shown in fig. 4.

The liquid on the membrane mainly depends on the hydrophilic drainage of a flow deflector, a polyether sulfone filter membrane with a circular working diameter of 12mm, a thickness of 30 mu m and a porosity of 50 percent is used, the vertical height of a flow guide pipe below the filter membrane is 10mm, the diameter of a pipe orifice of a liquid outlet is 4mm, and the structure 24 in figure 4 is the flow deflector. The system is kept working at an ultra low pressure with a negative pressure of less than 0.05 KPa. 2mL of healthy human whole blood was filtered without adding pretreatment solutions such as an infiltration solution, and the whole blood was directly filtered and collected for about 30 seconds when 500. mu.L of plasma was used in total. In the embodiment, almost no liquid column exists, the mechanism is different from the previous mechanism, the liquid flowing down of the membrane is realized mainly by the capillary suction principle of hydrophilic drainage, and the driving force is less than 0.05 KPa.

Example 10 identification of filtration Effect for different transition structures

The transition structure between the membrane and the flow guide pipe is designed into a sinking platform with the height of 2mm and the diameter of 14mm or a conical funnel structure with the height of 10mm and the diameters of two bottom surfaces of 14mm and 7mm respectively, other structures are consistent, and the stability influence of the two transition structures on the negative pressure formation of the ultra-low pressure generating device is compared.

A circular parylene microporous filter membrane with the working diameter of 14mm, the thickness of 15 mu m and the porosity of 52 percent is used, the fixing piece and the material of the flow guide pipe are polycarbonate injection molding pieces with untreated surfaces, the vertical height of the flow guide pipe is 100mm, and the diameter of a liquid outlet is 4.5 mm.

A45% v/v glycerol aqueous solution was used as the test liquid for comparison of filtration time.

The operation flow is as follows: 2mL of ethanol was added to wet the filter, 3mL of purified water was added, then 3mL of 45% v/v aqueous glycerol solution was filtered, and the total time on the filter required for the filtered liquid to pass completely through the filter was recorded. The following data were obtained after repeating the operation 5 times.

TABLE 1

Time of filtration

Repetition of 1

Repetition 2

Repetition of 3

Repetition of 4

Repetition 5

Average

Sinking platform

14s

11s

12s

13s

12s

12.4s

Conical funnel

34s

10s

19s

17s

19s

19.8s

From the experimental results, the transition structure between the filter membrane and the draft tube is a conical structure which is not as stable as the sinking platform structure. The main reason may be that the difference between the flow resistance of the sinking platform to the fluid and the flow resistance of the flow guide pipe to the fluid is large due to mismatching of the flow resistance, and a sudden change exists, so that the impedance coupling to the flow guide pipe is avoided, and the stable height of the liquid column is not influenced.

Example 11 identification of filtration Effect for different transition structures and different flow conduits

Different ultra-low pressure generating devices respectively adopt transition structures and flow guide pipe structures shown in the attached drawings 10-15, the structures of other parts of the ultra-low pressure generating devices are the same, and the first fixing pieces shown in the attached drawings 6 are adopted. The transition structures or the flow guide pipe structures are made of the same material, and the material is photosensitive resin coated by Teflon; the filter membrane is a parylene microporous membrane, the diameter of the working area is 12mm, the thickness is 13 microns, and the porosity is 47%.

Firstly adding 1mL of alcohol to soak the surface of the filter membrane, then pouring 3mL of pure water, adding 45% v/v glycerol aqueous solution after the surface of the filter membrane has no liquid, and calculating the filtration time.

The membrane-passing resistance in the membrane-immersed state is small, so that the instantaneous negative pressure in the first cavity in the filtration state is approximately equivalent to the negative pressure generated by a device below the membrane.

(1) As shown in fig. 10, the transition structure is a combination of a cylindrical structure i and a conical structure ii, and the flow guide pipe 15 is a circular pipe structure with a uniform inner diameter. The vertical height of I, II, III three-section is 15mm, 10mm, 20mm respectively, and cylindric structure internal diameter is 12mm, and honeycomb duct export internal diameter is 3 mm.

5 tests were carried out, and the filtration times were respectively: 16s, 16s, 16s, 17s, 15s, with a standard deviation of 0.71 s.

The negative pressure under the filter was found to be about 3.5 KPa.

(2) As shown in fig. 11, the transition structure is a combination of a cylindrical structure i and a conical structure ii, and the flow guide tube 15 is a circular tube structure with a uniform inner diameter. The vertical height of I, II, III three-section is 15mm, 10mm, 20mm respectively, and cylindric structure internal diameter is 12mm, and honeycomb duct export internal diameter is 1.5 mm.

5 tests were carried out, and the filtration times were respectively: 29s, 28s, 30s, 33s, 25s, standard deviation: 2.92 seconds.

The measured negative pressure was about 1.5 Kpa.

(3) As shown in fig. 12, the transition structure is a combination of a cylindrical structure i and a conical structure ii, and the flow guide pipe 15 is a circular pipe structure with a uniform inner diameter. The vertical height of I, II, III three-section is 15mm, 10mm, 10mm respectively, and cylindric structure internal diameter is 12mm, and honeycomb duct export internal diameter is 3 mm.

5 tests were carried out, and the filtration times were respectively: 21s, 20s, 30s, 24s, 24s, standard deviation: 3.90 seconds.

The measured negative pressure was about 2 KPa.

(4) As shown in fig. 13, the transition structure is a combination of a cylindrical structure i and a conical structure ii, and the flow guide pipe 15 is a circular pipe structure with a uniform inner diameter. The vertical height of I, II, III three-section is 15mm, 1mm, 20mm respectively, and cylindric structure internal diameter is 12mm, and honeycomb duct export internal diameter is 3 mm.

5 tests were carried out, and the filtration times were respectively: 16s, 17s, 16s, 13s, 15s, standard deviation: 1.52 seconds.

The negative pressure was found to be about 3.5 KPa.

(5) The transition structure and the draft tube 15 structure are combined into one, as shown in fig. 14, the vertical height of the draft tube assembly is 35mm, the draft tube assembly is gradually narrowed, the inner diameter of the inlet of the draft tube is 12mm, and the inner diameter of the outlet of the draft tube is 4 mm. The change angle of the slope of the three sections I, II and III is small, and the change between adjacent sections is not more than 1 degree, so that the gradual narrowing can be realized equivalently.

5 tests were carried out, and the filtration times were respectively: 18s, 55s, 26s, 13s, 59s, standard deviation: 21.37 seconds.

The measured negative pressure was about 3 KPa.

(6) The transition structure and the draft tube 15 structure are combined into a whole, as shown in fig. 15, a flow deflector is arranged in the draft tube, similar to fig. 4; the guide vanes are not shown in fig. 15.

The vertical height of the draft tube assembly is 17mm, the draft tube assembly gradually narrows, the inner diameter of the inlet of the draft tube is 12mm, and the inner diameter of the outlet of the draft tube is 4 mm.

5 tests were carried out, and the filtration times were respectively: 57s,67s,55s,67s,67s, standard deviation: 6.07s (seconds); actually measured negative pressure is as follows: <1 KPa.

In conclusion, the ultralow pressure generating device adopts different guide pipes and different transition structures, and the filtering effects are different.

Comparative example 1

A flow guide tube 15 made of the same material as in example 7 was connected to a common membrane separation apparatus (Millex-FG50 filter) under normal pressure by using a negative pressure of 0.5KPa (negative pressure generated by a membrane pump and calibrated by a barometer), and the microporous membrane used was a polycarbonate microporous membrane having a working area of 49mm in diameter, a thickness of 10 μm, and a porosity of 20%.

The separation of 3mL of a healthy human whole blood sample takes 600 seconds, and the phenomena of blood hemolysis, blood coagulation, cell sticking, breakage and the like are caused, so that the requirement of clinical sample processing cannot be realized.

Comparative example 2

The filtration was carried out at normal pressure using a common membrane separation apparatus at normal pressure (Millex-FG50 filter) using a polycarbonate microfiltration membrane having a working area of 49mm in diameter, a thickness of 10 μm and a porosity of 20%.

A3 mL sample of healthy human whole blood was isolated and infiltrated only through the membrane at atmospheric pressure, and no further filtration of the blood was possible. If the pressure is increased to ensure that the filtered solution at the outlet is output with the efficiency of more than 1mL/min, the pressure exceeds 40KPa after 1 minute, effective separation cannot be carried out, and unstable conditions such as hemolysis, blood coagulation, hole blockage and the like can occur.

It is to be understood that the described embodiments are merely a few embodiments of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Claims

1. An ultra-low pressure generating device is characterized by comprising a filter membrane with low membrane passing resistance, a filter membrane packaging device and a flow guide pipe; the filter membrane packaging device can be used for packaging the filter membrane with low membrane passing resistance to form a sealed filtering space; wherein, the membrane passing resistance in the filtration membrane infiltration state is far less than the pressure required for overcoming the interfacial surface tension after the liquid on the filtration membrane flows out; the draft tube can be used for generating negative pressure to form ultra-low pressure; the ultra low pressure is between 0.01KPa and 40 KPa; the outlet at the lower end of the flow guide pipe is arranged in the air, and the initial resistance of the filtering membrane is smaller than that of the flow guide pipe; due to the action of the surface tension of the filter membrane, a liquid column with stable height can be formed in the flow guide pipe, and the liquid column is used for generating ultra-low pressure and providing driving pressure required in the filtering process.

2. The ultra-low pressure generating apparatus as set forth in claim 1, wherein the low transmembrane resistance filter has a self-resistance of not more than 1.5 KPa.

3. The ultra-low pressure generating device as claimed in claim 1, wherein the low-filtration-resistance filter membrane is any one of a parylene microporous filter membrane, a polyimide microporous filter membrane, a polycarbonate microporous filter membrane, and a polyethersulfone filter membrane.

4. The ultra-low pressure generating apparatus as claimed in claim 1, wherein the filter membrane sealing means comprises a first fixing member and a second fixing member, and the first fixing member is detachably coupled to the second fixing member.

5. The ultra low pressure generating apparatus as claimed in claim 4, wherein the first fixing member includes a first chamber configured to store a sample to be filtered.

6. The ultra-low pressure generating apparatus as claimed in claim 5, wherein the flow guide pipe is directly connected to the second fixing member, or the second fixing member is connected to the transition structure, and the transition structure is connected to the flow guide pipe.

7. The ultra low pressure generating apparatus as claimed in claim 6, wherein the transition structure is at least one of a sinking platform structure, a cone structure and a barrel structure.

8. The ultra-low pressure generating apparatus as claimed in claim 7, wherein a flow guide is provided in the conical structure or a flow guide is provided in the cylindrical structure.

9. Use of an ultra low pressure generating device for isolating a biological sample, wherein the device is according to any one of claims 1 to 8.

10. A method for using an ultra-low pressure generating apparatus according to any one of claims 1 to 8, comprising the steps of:

(2) connecting and fixing the first fixing piece and the second fixing piece;

(4) adding low surface tension liquid to soak the filter membrane into the first cavity, then adding liquid A, wherein the liquid A is pure water or other liquid with different densities, the liquid A in the first cavity enters the lower part of the filter membrane, the liquid on the membrane keeps the membrane in a soaking state, the liquid A continuously enters the flow guide pipe, and finally liquid columns with stable height appear in the flow guide pipe to form negative pressure with certain size.