A needle filter

Abstract

The present application relates to laboratory filtration equipment technical field, provide a kind of needle filter, comprising: shell, the first end of shell is provided with inlet;Pressure cylinder, along the axial projection of shell is arranged at the first end of shell, and located the outside of inlet, one end of pressure cylinder is communicated with the inside of shell, the end of pressure cylinder away from shell is closed and is provided with vent hole;Buffer cavity, set to the inside of shell, buffer cavity is communicated with pressure cylinder and inlet, and one end of buffer cavity away from pressure cylinder is provided with filter membrane;Pressure visualization component, set to pressure cylinder, pressure visualization component is configured to be able to real-time response the internal pressure of buffer cavity, and internal pressure is converted into visual pressure signal, which can be directly observed, to indicate operator to adjust injection speed;The present application is simple in structure, low in cost, operator can accurately master the pressure change in filtration process, and adjusts injection speed or stops injection according to pressure change, eliminates the operation risk of blind pressure.

Description

Technical Field

[0001] This invention relates to the field of laboratory filtration equipment technology, and specifically to a needle-type filter. Background Technology

[0002] Needle filters are critical consumables for sample pretreatment in environmental and consumer product testing. Taking the detection of phthalates in black plastics as an example, after extraction with organic solvents, the extract contains a large amount of carbon black particles, undissolved polymers, and colloidal substances. When using conventional needle filters (0.22μm or 0.45μm PTFE membranes), the following problems commonly exist: Rapid clogging of the filter membrane: Fine particles form a filter cake on the surface of the filter membrane, causing a sharp increase in filtration resistance.

[0003] Manual injection is difficult: the operator needs to apply a large amount of force, which is strenuous.

[0004] Filter membrane rupture: The operator applies too much force, causing localized pressure concentration and rupture of the filter membrane.

[0005] Sample splashing: After the filter membrane ruptures, the sample liquid splashes from the gaps or damage points of the filter, causing sample loss, contaminating the workbench, and posing a safety risk.

[0006] All existing needle-type filters lack pressure monitoring or visualization capabilities, forcing operators to rely entirely on touch to judge pressure. This lack of quantification makes them highly susceptible to membrane rupture due to excessive pressure application. This "blind push" approach is one of the root causes of filtration failure. Summary of the Invention

[0007] This invention aims to solve at least one of the technical problems existing in related technologies. To this end, this invention proposes a needle-type filter that can realize real-time sensing and visualization of filtration pressure, enabling operators to accurately grasp pressure changes during the filtration process and adjust the injection speed or stop injection according to pressure changes, eliminating the operational risks of blindly applying pressure.

[0008] A needle-type filter according to an embodiment of the present invention includes: The outer casing, wherein an inlet is provided at the first end of the outer casing; A pressure cylinder is provided at the first end of the outer shell along the axial direction of the outer shell and located outside the inlet. One end of the pressure cylinder is connected to the interior of the outer shell, and the end of the pressure cylinder away from the outer shell is closed and provided with a vent hole. A buffer chamber is disposed inside the outer shell. The buffer chamber is connected to the pressure cylinder and the inlet, and a filter membrane is disposed at the end of the buffer chamber opposite to the pressure cylinder. A pressure visualization component is disposed in the pressure cylinder. The pressure visualization component is configured to sense the internal pressure of the buffer chamber in real time and convert the internal pressure into a visually observable pressure signal to instruct the operator to adjust the injection speed.

[0009] A needle-type filter according to an embodiment of the present invention further includes: A support layer is disposed between the buffer cavity and the filter membrane. The edge of the support layer is connected to the inner wall of the outer shell. The support layer is provided with multiple through holes. The side of the support layer opposite to the buffer cavity is attached to the filter membrane.

[0010] According to one embodiment of the needle filter, the sum of the surface areas of the plurality of through holes accounts for 30% to 50% of the surface area of ​​the support layer.

[0011] According to one embodiment of the needle filter of the present invention, the through hole is a round hole with a diameter of 0.5~1.0mm.

[0012] According to an embodiment of the needle-type filter of the present invention, the pressure visualization component includes: An elastic seal is disposed inside the pressure cylinder, the edge of the elastic seal is sealed to the inner wall of the pressure cylinder, and the elastic seal can undergo elastic deformation under the pressure inside the buffer cavity; A transparent viewing window is provided in the area of ​​the pressure cylinder corresponding to the deformation of the elastic seal.

[0013] According to one embodiment of the needle filter, a scale is provided at the transparent window to indicate the amount of deformation of the elastic seal.

[0014] According to an embodiment of the needle-type filter of the present invention, the scale is arranged along the axial direction of the housing and includes at least a first scale line, a second scale line, and a third scale line, and the first scale line, the second scale line, and the third scale line are arranged sequentially along the direction of increasing pressure; when the highest point of deformation of the elastic seal does not exceed the first scale line, it indicates that the filtration pressure is in a safe state; when the highest point of deformation of the elastic seal reaches or exceeds the second scale line, it indicates that the injection should be slowed down or stopped; when the highest point of deformation of the elastic seal reaches the third scale line, it indicates that the filtration pressure has reached a dangerous threshold and the injection should be stopped.

[0015] According to one embodiment of the needle filter, the distance between the end face of the pressure cylinder facing away from the outer shell and the first end face of the outer shell is 5~8mm.

[0016] According to one embodiment of the needle filter of the present invention, the pore size of the filter membrane is 0.22μm~0.45μm.

[0017] According to one embodiment of the needle filter of the present invention, the outer shell and the pressure cylinder are integrally injection molded and are both cylindrical.

[0018] According to one embodiment of the needle filter, the second end of the housing is provided with an outlet for connection to a collection container.

[0019] The above-described one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects: 1) Pressure visualization: The invisible internal pressure is transformed into visible displacement through the pressure visualization component. Combined with the scale, it provides quantitative indication, enabling operators to accurately grasp the pressure changes during the filtration process and eliminating the risk of filter membrane rupture caused by blindly applying pressure.

[0020] 2) Dynamic adaptive pressure buffer: By utilizing the synergistic effect of the pressure cylinder and the elastic seal, the pressure and buffer volume are dynamically and adaptively adjusted. The greater the pressure, the greater the deformation of the elastic seal and the larger the dynamic buffer volume, which can partially absorb the instantaneous pressure peak of manual injection.

[0021] 3) Prevent sample splashing and loss. Through the dual protection of pressure warning and pressure buffer, the filter membrane is prevented from rupturing due to local pressure concentration, and the phenomenon of sample liquid splashing from filter gaps or damaged areas is eliminated, ensuring the safety of laboratory operations and the cleanliness of the environment.

[0022] 4) Based on conventional needle filters, a pressure cylinder is integrated into the top of the housing using a one-piece injection molding process, and two additional components, an elastic seal and a transparent window, are added. No electronic components, batteries or complex circuits are required, resulting in low manufacturing costs and meeting the low-cost mass production requirements for disposable consumables.

[0023] 5) The operation is intuitive, the scale lines have clear meanings, and can be understood without training.

[0024] 6) It is highly versatile and can directly replace existing conventional needle filters, making it easy to promote and apply quickly.

[0025] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention and are not considered as limitations on this application. Moreover, those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0027] Figure 1 This is a schematic structural diagram of a needle-type filter provided by the present invention.

[0028] Figure 2 This is a cross-sectional view of a needle-type filter provided by the present invention.

[0029] Figure label: 1. Outer shell; 2. Pressure cylinder; 3. Buffer chamber; 4. Inlet; 5. Filter membrane; 6. Support layer; 7. Flexible seal; 8. Transparent window; 9. Outlet. Detailed Implementation

[0030] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0031] The specific terms used in this specification are for illustrative purposes only and are not intended to limit the illustrated embodiments. For example, expressions such as "same" and "identical" not only indicate a strictly identical state, but also indicate a state with tolerances or differences in the degree of functionality. For example, expressions indicating relative or absolute arrangement such as "in a certain direction," "along a certain direction," "side by side," "perpendicular," "centered on," "concentric," or "coaxial" not only strictly indicate such an arrangement, but also indicate a state of relative displacement by tolerances or angles or distances with the same degree of functionality.

[0032] The terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.

[0033] Furthermore, features specified as "first" or "second" may explicitly or implicitly include one or more of those features. In the description of this invention, unless otherwise stated, "multiple" means two or more. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] All needle filters in the current technology do not have pressure monitoring or visualization functions. Operators rely entirely on touch to judge the filtration pressure, which is a "blind push" state. This can easily lead to problems such as rapid clogging of the filter membrane due to excessive pressure, difficulty in manual injection, filter membrane rupture, and sample splashing.

[0036] The following is combined with Figures 1 to 2 This invention describes a needle-type filter.

[0037] This invention provides a needle-type filter, comprising: a housing 1, a pressure cylinder 2, a buffer chamber 3, and a pressure visualization component. The housing 1 has an inlet 4 at its first end. The pressure cylinder 2 protrudes axially from the first end of the housing 1 and is located outside the inlet 4. One end of the pressure cylinder 2 communicates with the interior of the housing 1, and the end of the pressure cylinder 2 facing away from the housing 1 is closed and has a vent hole for air circulation. The buffer chamber 3 is located inside the housing 1 and communicates with both the pressure cylinder 2 and the inlet 4. That is, the inlet 4 and the pressure cylinder 2 are two parallel branches, both leading to the buffer chamber 3. A filter membrane 5 is located at the end of the buffer chamber 3 facing away from the pressure cylinder 2. The pressure visualization component is located on the pressure cylinder 2 and is configured to sense the internal pressure of the buffer chamber 3 in real time and convert the internal pressure into a visually observable pressure signal to instruct the operator to adjust the injection speed.

[0038] Through the above solution, the present invention, by setting a pressure cylinder 2 connected to the buffer chamber 3 at the first end of the outer shell 1 and integrating a pressure visualization component on the pressure cylinder 2, can realize real-time sensing and visualization output of filtration pressure on the needle filter, converting the invisible internal pressure into a pressure signal that the operator can intuitively observe. This allows the operator to accurately grasp the pressure changes during the filtration process and adjust the injection speed or stop injection according to the pressure changes, eliminating the operational risks of blindly applying pressure. By adjusting the injection speed in a timely manner, the formation and rapid compaction of the filter cake under high pressure are avoided, allowing the particulate matter to form a looser filter cake layer on the filter membrane surface, slowing down the rate of increase in filtration resistance, extending the effective filtration time of a single filter, and improving filtration efficiency.

[0039] In addition, operators can adjust the injection force in a timely manner based on the visualized pressure signal, and actively slow down or stop the injection when the pressure rises to avoid the sudden pressure increase causing local stress concentration and rupture of the filter membrane, thus greatly reducing the filtration failure rate. Since the risk of filter membrane rupture is eliminated, the situation of sample liquid splashing from the gaps or damaged parts of the filter is fundamentally avoided. This not only prevents the deviation of test results caused by sample loss, but also avoids the safety hazards of toxic and harmful samples contaminating the operating table and endangering the operators.

[0040] The vent hole at the top of the pressure cylinder 2 can be round, square, or other shapes, with the diameter of the round hole being 0.2~1.0mm.

[0041] The first end of the outer shell 1 has an inlet 4 for connecting to a syringe, and the second end has an outlet 9 for connecting to a collection container. Inlet 4 uses an industry-standard conical Luer female connector design, allowing for a sealed connection with the male connectors of all commercially available 1mL, 2mL, 5mL, and 10mL disposable syringes. This eliminates the need for additional adapters or specialized equipment, directly replacing existing conventional needle filters and facilitating rapid adoption. Outlet 9 uses a matching conical Luer male connector design, allowing for a sealed connection with the female connectors of all commercially available centrifuge tubes, test tubes, sample vials, chromatographic injection vials, and other collection containers, meeting the sample collection needs of various testing scenarios.

[0042] Optionally, the outer shell 1 and the pressure cylinder 2 are integrally injection molded and are both cylindrical. Polypropylene (PP) can be used as the material, which has excellent resistance to organic solvents, good strength and low cost, fully meeting the requirements for disposable laboratory consumables. For scenarios requiring higher temperature resistance or corrosion resistance, polycarbonate (PC) or polyetheretherketone (PEEK) materials can be used.

[0043] Reference Figure 2Furthermore, it also includes a support layer 6, which is disposed between the buffer cavity 3 and the filter membrane 5. The edge of the support layer 6 is connected to the inner wall of the outer shell 1, forming the bottom of the buffer cavity 3. The support layer 6 is uniformly provided with multiple through holes, and the side of the support layer 6 away from the buffer cavity 3 is attached to the filter membrane 5.

[0044] With this configuration, the support layer 6 fully conforms to the entire effective filtration area of ​​the filter membrane 5, evenly distributing the pressure transmitted from the buffer chamber 3 to every point of the filter membrane. This completely avoids the problems of local stress concentration, depressions, wrinkles, and cracks caused by the filter membrane being fixed only at the edges and lacking support in the central area, as seen in existing technologies. Through the multiple through holes evenly distributed on the support layer 6, the liquid flowing out of the buffer chamber 3 is evenly distributed to the surface of the filter membrane 5, preventing localized rapid blockage caused by the liquid flow from the inlet 4 directly impacting the center of the filter membrane. This allows particulate matter to form a filter cake layer of uniform thickness and loose structure on the filter membrane surface, reducing the rate of increase in filtration resistance and increasing the effective filtration capacity of a single filter. Furthermore, the edge of the support layer 6 is sealed to the inner wall of the outer shell 1, and its upper surface directly forms the bottom surface of the buffer chamber 3, creating a structurally stable closed pressure space. This ensures that pressure changes within the buffer chamber 3 can be accurately transmitted to the pressure visualization component inside the pressure cylinder 2, guaranteeing the reliability of the visualization signal.

[0045] Furthermore, the sum of the surface areas of multiple through holes accounts for 30% to 50% of the surface area of ​​the support layer 6. When the porosity is less than 30%, the liquid flow area is insufficient and the filtration speed is slow; when the porosity is greater than 50%, the strength of the support layer 6 is reduced.

[0046] This configuration ensures that the pressure within the buffer chamber 3 is uniformly and synchronously transmitted to the entire surface of the support layer 6, thus acting evenly on the filter membrane and preventing sudden local pressure increases caused by uneven pressure distribution. Simultaneously, the stable pressure field ensures that pressure changes are accurately transmitted to the pressure visualization component, reducing pressure indication errors and improving the reliability of pressure visualization.

[0047] In some embodiments, the through hole is a round hole with a diameter of 0.5~1.0 mm. When the diameter is less than 0.5 mm, the resistance to liquid flow will increase, and large particles of impurities are prone to accumulate at the inlet 4 of the through hole, causing the support layer 6 to fail. When the diameter is greater than 1.0 mm, undissolved polymer clumps, colloidal flocs and hard carbon black aggregates with a diameter of 0.5~1.0 mm will directly impact the surface of the filter membrane, causing local puncture or rapid blockage of the filter membrane.

[0048] In some embodiments, the pore size of the filter membrane 5 is 0.22 μm to 0.45 μm.

[0049] With this configuration, the 0.45μm pore size is suitable for filtering most samples containing carbon black and polymer particles, and can effectively retain fine particles with a diameter ≥0.45μm, meeting the pretreatment requirements for the detection of common pollutants such as phthalates and polycyclic aromatic hydrocarbons; the 0.22μm pore size is suitable for high-precision detection scenarios that require sterilization or retention of ultrafine particles. This pore size range covers more than 90% of the needle-type filtration needs in the laboratory, eliminating the need to replace filters with other specifications and improving detection efficiency.

[0050] The pore size of the support layer 6 is 1000 to 4500 times that of the filter membrane 5. The two form a two-stage gradient filtration structure of large particle pre-filtration and fine particle fine filtration, which greatly reduces the load on the filter membrane 5 and effectively prevents large particles from puncturing the filter membrane.

[0051] The filter membrane 5 can be made of polytetrafluoroethylene (PTFE), which has extremely strong resistance to organic solvent corrosion. It can withstand most commonly used organic solvents in laboratories, such as hexane, methanol, acetonitrile, and dichloromethane, and will not precipitate any impurities that would interfere with the test results. Compared with filter membranes made of materials such as nylon and polyethersulfone (PES), PTFE filter membranes have a longer service life in organic solvents and will not swell, deform, or dissolve, ensuring stable pressure transmission during the filtration process and avoiding pressure indication deviations caused by filter membrane swelling.

[0052] like Figures 1-2 As shown, in some embodiments, the outer shell 1 is cylindrical, and the support layer 6 is a disc-shaped flat plate structure with a diameter exactly equal to the inner diameter of the outer shell 1, horizontally positioned between the buffer cavity 3 and the filter membrane 5. The edge of the support layer 6 is tightly connected to the inner wall of the outer shell 1 through an interference fit, ensuring no liquid leakage from the edge. The upper surface of the support layer 6 and the side wall of the buffer cavity 3 together form a closed buffer space, and the lower surface of the support layer 6 is fully and tightly attached to the upper surface of the filter membrane 5.

[0053] The support layer 6 can be made of polypropylene (PP) material, which is integrally molded by injection molding process. It is low in cost and resistant to most organic solvents, such as n-hexane, methanol, acetonitrile, etc. Alternatively, it can be made of stainless steel sintered porous plate material, which is resistant to strong acids, strong alkalis and highly corrosive organic solvents, and is suitable for filtering special samples in chemical, pharmaceutical and other fields.

[0054] The thickness of the support layer 6 ranges from 1 to 2 mm. When the thickness is less than 1 mm, the support layer 6 is not strong enough and is prone to bending and deformation under high pressure. When the thickness is greater than 2 mm, it will increase the flow resistance of the liquid and prolong the filtration time.

[0055] The pore size of the support layer 6 ranges from 0.5 to 1.0 mm. When the pore size is less than 0.5 mm, the resistance to liquid flow is too high; when the pore size is greater than 1.0 mm, the support effect on the filter membrane 5 decreases, and it cannot effectively prevent large particles of impurities from passing through.

[0056] In a preferred embodiment of the present invention, the support layer 6 is a polypropylene disk with a diameter of 11 mm and a thickness of 1.5 mm, on which a plurality of circular through holes with a diameter of 0.8 mm are evenly distributed, and the porosity is 40%. The support layer 6 is pressed into the shell 1 by interference fit, and its lower surface is fully attached to the filter membrane 5.

[0057] When filtering phthalate extract from black ABS plastic, the solution is evenly distributed across the entire filter membrane surface through support layer 6. The pores in support layer 6 prevent undissolved polymer agglomerates with a diameter greater than 0.8 mm from passing through. Experimental results show that the filter using this support layer 6 has a membrane breakage rate of 0% and an average filtration time of 42 s, while the control group filter without support layer 6 has a membrane breakage rate of 25% and an average filtration time of 75 s.

[0058] Preferably, for scenarios requiring higher filtration precision, the support layer 6 can adopt a double-layer structure. The upper layer is a large-pore coarse filter layer (e.g., pore size 1.0 mm) used to intercept large particulate impurities; the lower layer is a small-pore fine filter layer (e.g., pore size 0.5 mm) used to further distribute the liquid evenly and support the filter membrane. The two layers are combined into one by hot pressing, with an overall thickness of 2 mm.

[0059] In some embodiments, the pressure visualization component includes an elastic seal 7 and a transparent window 8. The elastic seal 7 is disposed inside the pressure cylinder 2, and the edge of the elastic seal 7 is sealed to the inner wall of the pressure cylinder 2. The elastic seal 7 can undergo elastic deformation under the pressure inside the buffer chamber 3. The transparent window 8 is disposed in the area of ​​the pressure cylinder 2 corresponding to the deformation of the elastic seal 7.

[0060] With this configuration, the elastic seal 7 directly utilizes the internal pressure of the buffer chamber 3 to drive its own elastic deformation, eliminating the need for any electronic components such as batteries, sensors, and circuits. This not only reduces product costs but also avoids the risks of corrosion and short circuits of electronic components in organic solvent environments and eliminates the possibility of impurities precipitated from electronic components interfering with detection results. The edge of the elastic seal 7 in this invention is sealed to the inner wall of the pressure cylinder 2, ensuring that the buffer chamber 3 forms a closed pressure space. Through its own deformation, it directly converts invisible pressure changes into visible displacement changes. The transparent window 8 faces the entire deformation area of ​​the elastic seal 7, allowing for a complete and clear observation of the entire process of the elastic seal 7 from flat to its maximum bulge. With the clear observation through the transparent window 8, the operator can accurately judge the internal pressure by the deformation height. In addition, while sensing pressure, the bulging deformation of the elastic seal 7 dynamically expands the internal volume of the pressure cylinder 2, thereby absorbing the pressure during the filtration process and playing a pressure buffering role. This allows pressure visualization and pressure protection functions to be achieved simultaneously without additional components.

[0061] like Figure 2 As shown, the elastic seal 7 is horizontally disposed inside the pressure cylinder 2. The edge of the elastic seal 7 is circumferentially sealed to the inner wall of the pressure cylinder 2, dividing the internal space of the pressure cylinder 2 into upper and lower parts. The lower part is connected to the buffer cavity 3. The transparent window 8 is sealed and covered on the outer wall of the pressure cylinder 2 to ensure that the entire deformation process of the elastic seal 7 can be observed.

[0062] The elastic seal 7 is made of elastic material of uniform thickness. Within the working pressure range, its deformation is linearly positively correlated with the internal pressure of the buffer chamber 3. With the clear observation through the transparent window 8, the operator can accurately judge the internal pressure by the deformation height.

[0063] For example, the elastic seal 7 can be made of fluororubber (FKM), which has excellent resistance to organic solvents and can withstand most commonly used laboratory organic solvents such as n-hexane, methanol, acetonitrile, and dichloromethane. It also has an elastic recovery rate greater than 95% and exhibits no permanent deformation after repeated deformation. Alternatively, it can be made of PTFE-coated silicone, with an inner silicone layer providing elasticity and an outer PTFE layer providing corrosion resistance. This allows it to withstand highly corrosive liquids such as concentrated sulfuric acid and concentrated nitric acid, making it suitable for filtering special chemical samples.

[0064] The diameter of the elastic seal 7 is equal to the inner diameter of the pressure cylinder 2, ranging from 6 to 10 mm, and the thickness ranges from 0.2 to 0.5 mm. When the thickness is less than 0.2 mm, the elastic seal 7 is prone to breakage; when the thickness is greater than 0.5 mm, the deformation sensitivity decreases, and no significant deformation can be produced under low pressure.

[0065] The elastic seal 7 is connected to the pressure cylinder 2 by ultrasonic welding, adhesive bonding, or secondary injection molding. Among them, adhesive bonding uses epoxy resin adhesive that is resistant to organic solvents. Secondary injection molding pre-places the elastic seal 7 into the mold and integrally injection molds it with the pressure cylinder 2, which has the best sealing effect, but the mold cost is relatively high. Ultrasonic welding is the preferred method because it has a fast welding speed, high sealing strength, and no adhesive exudation.

[0066] The transparent viewing window 8 is located on the outer wall of the pressure cylinder 2. It can be made of transparent polypropylene (PP) or polycarbonate (PC), with a light transmittance of more than 90%, strong impact resistance, and is not easy to scratch, providing a better observation effect.

[0067] Furthermore, a scale is provided at the transparent window 8 to indicate the amount of deformation of the elastic seal 7.

[0068] In some embodiments, the scale is arranged along the axial direction of the housing 1, including at least a first scale line, a second scale line and a third scale line, and the first scale line, the second scale line and the third scale line are arranged sequentially along the direction of increasing pressure; the scale line adopts a horizontal straight line design, and the length is equal to the width of the transparent window 8 to ensure clear observation from any angle.

[0069] When the highest point of deformation of the elastic seal 7 does not exceed the first scale line, it indicates that the filter membrane 5 is partially blocked, indicating that the filtration pressure is in a safe state; when the highest point of deformation of the elastic seal 7 reaches or exceeds the second scale line, it indicates that the injection should be slowed down or stopped; when the highest point of deformation of the elastic seal 7 reaches the third scale line, it indicates that the filtration pressure has reached the danger threshold and the injection should be stopped.

[0070] Specifically, the three-level scale lines precisely correspond to the three stages of the filtration process, forming a progressive safety warning. The first graduation line clearly defines the safe operating area, allowing operators to inject with confidence; the second graduation line provides an early warning signal, allowing sufficient reaction time; the third graduation line marks the absolute stop line, preventing excessive pressure application. This tiered warning mechanism can significantly reduce the risk of filter membrane rupture and eliminate safety hazards and sample loss caused by sample splashing.

[0071] With this configuration, the scale is arranged along the axis of the outer shell 1, which is consistent with the deformation direction of the elastic seal 7. The observation is intuitive and natural. While pushing the syringe, the operator can scan the window with his peripheral vision to read the scale without changing the operating posture or interrupting the injection process, thus improving the operating efficiency.

[0072] To further enhance visibility, different levels of scale lines can be distinguished by color: the first scale line is green, representing the safety line; the second scale line is yellow, representing the warning line; and the third scale line is red, representing the danger line.

[0073] In some specific embodiments, when filtering 5 mL of black ABS plastic phthalate extract, during the first 1.5 mL of filtration, the highest point of deformation of the elastic seal 7 remained below the first graduation line, and the operator maintained a normal injection speed. When filtering to 1.5-3 mL, the highest point of deformation of the elastic seal 7 rose to the second graduation line. Each time it reached this line, the operator paused for 2 seconds, allowing it to return to the first graduation line before continuing injection. When filtering to 3-5 mL, the highest point of deformation of the elastic seal 7 did not exceed the second graduation line, and filtration was successfully completed. Throughout the entire process, the filter membrane remained intact, and there was no sample splashing.

[0074] The distance between the end face of the pressure cylinder 2 away from the outer shell 1 and the first end face of the outer shell 1 is 5~8mm. That is, the upper end face of the pressure cylinder 2 is 5~8mm higher than the upper surface of the outer shell 1.

[0075] This configuration provides deformation space for the elastic seal 7. The height range of 5 to 8 mm perfectly matches the elastic deformation limit of the elastic seal 7 with a thickness of 0.2 to 0.5 mm. When the height is less than 5 mm, the maximum deformation of the elastic seal 7 is insufficient, resulting in a large indication error. When the height is greater than 8 mm, the deformation of the elastic seal 7 exceeds its elastic limit, and it cannot return to its initial position after repeated use, causing the pressure indication to fail.

[0076] It provides ample dynamic buffer volume to effectively absorb pressure peaks, reducing the instantaneous pressure on the filter membrane and preventing membrane rupture due to excessive force. Furthermore, it ensures uniform distribution of the three-level scale, improving observation and identification, preventing overlapping and indistinguishable scale lines due to excessive spacing.

[0077] Finally, it should be noted that the above embodiments are only for illustrating the present invention and not for limiting the present invention. Although the present invention has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of the present invention do not depart from the spirit and scope of the technical solutions of the present invention and should be covered within the scope of the claims of the present invention.

Claims

1. A needle-type filter, characterized in that, include: The outer shell (1) has an inlet (4) at its first end. The pressure cylinder (2) is convex along the axial direction of the outer shell (1) at the first end of the outer shell (1) and located outside the inlet (4). One end of the pressure cylinder (2) is connected to the interior of the outer shell (1), and the end of the pressure cylinder (2) away from the outer shell (1) is closed and has a vent hole. A buffer chamber (3) is disposed inside the outer shell (1). The buffer chamber (3) is connected to the pressure cylinder (2) and the inlet (4). A filter membrane (5) is disposed at the end of the buffer chamber (3) away from the pressure cylinder (2). A pressure visualization component is provided in the pressure cylinder (2). The pressure visualization component is configured to sense the internal pressure of the buffer chamber (3) in real time and convert the internal pressure into a visual pressure signal that can be observed intuitively, so as to instruct the operator to adjust the injection speed.

2. The needle-type filter according to claim 1, characterized in that, Also includes: A support layer (6) is disposed between the buffer cavity (3) and the filter membrane (5). The edge of the support layer (6) is connected to the inner wall of the outer shell (1). The support layer (6) is provided with multiple through holes. The side of the support layer (6) away from the buffer cavity (3) is attached to the filter membrane (5).

3. The needle-type filter according to claim 2, characterized in that, The sum of the surface areas of the plurality of through holes accounts for 30% to 50% of the surface area of ​​the support layer (6).

4. The needle-type filter according to claim 2, characterized in that, The through hole is a round hole with a diameter of 0.5~1.0mm.

5. The needle-type filter according to claim 1, characterized in that, The pressure visualization component includes: An elastic seal (7) is provided inside the pressure cylinder (2). The edge of the elastic seal (7) is sealed to the inner wall of the pressure cylinder (2). The elastic seal (7) can undergo elastic deformation under the pressure inside the buffer cavity (3). A transparent window (8) is provided in the area of ​​the pressure cylinder (2) corresponding to the deformation of the elastic seal (7).

6. The needle-type filter according to claim 5, characterized in that, A scale is provided at the transparent window (8) to indicate the amount of deformation of the elastic seal (7).

7. The needle-type filter according to claim 6, characterized in that, The scale is arranged along the axial direction of the outer casing (1), and includes at least a first scale line, a second scale line, and a third scale line. The first scale line, the second scale line, and the third scale line are arranged sequentially in the direction of increasing pressure. When the highest point of deformation of the elastic seal (7) does not exceed the first scale line, it indicates that the filtration pressure is in a safe state. When the highest point of deformation of the elastic seal (7) reaches or exceeds the second scale line, it indicates that the injection needs to be slowed down or stopped. When the highest point of deformation of the elastic seal (7) reaches the third scale line, it indicates that the filtration pressure has reached a dangerous threshold and the injection should be stopped.

8. The needle filter according to any one of claims 1-7, characterized in that, The distance between the end face of the pressure cylinder (2) facing away from the outer shell (1) and the first end face of the outer shell (1) is 5~8mm.

9. The needle filter according to any one of claims 1-7, characterized in that, The outer shell (1) and the pressure cylinder (2) are integrally injection molded and are both cylindrical.

10. The needle filter according to any one of claims 1-7, characterized in that, The second end of the outer shell (1) is provided with an outlet (9) for connecting to a collection container.

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