A dairy product activity detection device

Abstract

This invention discloses a dairy product activity testing device, comprising a dual-plunger dilution mechanism mounted on a test bench, wherein the dual-plunger dilution mechanism is connected to a dual-piston drive mechanism mounted on one side thereof, and a multi-point coating mechanism is provided on the other side of the dual-plunger dilution mechanism. The outlet end of the dual-plunger dilution mechanism is connected to the inlet end of the multi-point coating mechanism via a connecting hose, and an on / off valve is installed on the connecting hose. A petri dish is placed on the multi-point coating mechanism. This invention can effectively improve the efficiency and effect of dilution and coating, enhance the accuracy of the operation, and avoid contamination from external sources. This invention is applicable to the technical field of dilution and coating in dairy product activity testing.

Description

Technical Field

[0001] This invention belongs to the technical field of dairy product testing, specifically, it relates to a dairy product activity testing device. Background Technology

[0002] In the detection of dairy product activity (such as the detection of live probiotic counts and microbial contamination), dilution and coating are the core steps in sample pretreatment and isolation culture, which directly affect the accuracy, repeatability and efficiency of the test results.

[0003] Current manual dilution methods rely on pipettes and pipettes to manually aspirate samples and diluents. During manual operation, factors such as pipette aspiration speed, release speed, whether the pipette tip is rinsed, and errors in liquid level readings lead to discrepancies between the actual and theoretical volumes. In multi-stage dilutions, the errors at each stage accumulate and amplify, ultimately resulting in a significant deviation between the actual and theoretical concentrations at the target dilution level. Dairy samples contain large molecules such as proteins and fats, and have a viscous texture, making it difficult to achieve complete and homogeneous mixing of the sample and diluent during manual dilution, and also resulting in lengthy dilution times.

[0004] Current manual plating methods rely on sterile glass plating rods or L-shaped plating applicators to evenly distribute the sample solution on the culture medium surface through circular swirls, which is highly dependent on operator skill. Excessive pressure during swirls can damage microbial cells (e.g., rupture of probiotic cell membranes), affecting growth; insufficient pressure prevents the sample solution from spreading to the edges of the medium, resulting in colonies concentrated in the center. The lack of standardized swirl patterns in manual plating leads to uneven distribution of the sample solution, with some areas having too much (colony overlap) and others too little. Furthermore, improper sample volume control and uneven colony distribution result in some plates being inaccurately counted due to colony overlap, requiring re-plating. Even when counts are achieved, localized concentration deviations can distort the results. Summary of the Invention

[0005] This invention provides a dairy product activity detection device to improve the efficiency and effectiveness of dilution and coating, enhance the accuracy of operations, and prevent external contamination.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A dairy product activity testing device includes a dual-plunger dilution mechanism mounted on a test bench. The dual-plunger dilution mechanism is connected to a dual-piston drive mechanism mounted on one side of the dual-plunger dilution mechanism. A multi-point coating mechanism is provided on the other side of the dual-plunger dilution mechanism. The outlet end of the dual-plunger dilution mechanism is connected to the inlet end of the multi-point coating mechanism via a connecting hose. An on / off valve is installed on the connecting hose. A petri dish is placed on the multi-point coating mechanism.

[0007] A further technical solution is that the dual-plunger dilution mechanism includes two horizontal dilution cylinders arranged opposite each other. The two horizontal dilution cylinders are connected at their close ends via a conductive adapter, and the conductive adapter is connected to a connecting hose. A movable plunger is assembled inside each horizontal dilution cylinder. A plunger rod connected to the movable plunger extends movably from the end of the horizontal dilution cylinder away from the conductive adapter, and the plunger rod is connected to a dual-piston drive mechanism.

[0008] A further technical solution is that the horizontal dilution cylinder includes a cylindrical body, a constriction nozzle coaxially constructed at one end of the cylindrical body near the conductive adapter, a cylinder cap detachably connected to the other end of the cylindrical body, and an inlet connector connected to the upper part of the peripheral wall of the cylindrical body near the cylinder cap; the movable plunger has a frustum-shaped structure, and when the movable plunger is located inside the constriction nozzle, the movable plunger is adapted to the inner cavity of the constriction nozzle.

[0009] A further technical solution is to provide multiple swirling grooves spaced circumferentially on the inner wall of the constricting nozzle, with each swirling groove extending from the large-diameter end of the constricting nozzle to the conductive adapter.

[0010] A further technical solution is that the conductive adapter includes an assembly constructed at the connection of two horizontal dilution cylinders, a vertical guide post rotatably connected to the assembly, a connecting hole for connecting the two horizontal dilution cylinders on the assembly, a first guide hole for connecting the two horizontal dilution cylinders through the connecting hole on the vertical guide post, and a second guide hole for communicating with the first guide hole on the vertical guide post, the second guide hole being connected to a connecting hose.

[0011] A further technical solution is that the dual-piston drive mechanism includes a piston sleeve parallel to the axis of the horizontal dilution cylinder, with connecting caps detachably connected to both ends of the piston sleeve, and two piston bodies spaced apart along its axial direction inside the piston sleeve. Piston rods are connected to the ends of the two piston bodies that are far apart from each other, and each piston rod extends movably out of its corresponding connecting cap. The piston rods are connected to corresponding movable plungers via adapter arms. A first drive chamber is formed inside the piston sleeve and between the two piston bodies, and a second drive chamber is formed inside the piston sleeve and between the piston bodies and their corresponding connecting caps. A first connector is connected to the middle of the first drive chamber, and a second connector is connected to the second drive chamber near the connecting cap.

[0012] A further technical solution is that the multi-point coating mechanism includes a coating table with linear motors symmetrically installed on both sides, a placement seat provided below the coating table, and vertical guide rails symmetrically installed on both sides of the placement seat. Each linear motor is connected to the corresponding vertical guide rail for transmission. The culture dish is placed on the placement seat, and the coating table is connected to the connecting tubing.

[0013] A further technical solution is that the coating table includes a top cover, a base platform, and a coating table body connected vertically downwards in sequence. An intermediate chamber is formed in the base platform body, and a coating chamber communicating with the intermediate chamber is formed in the coating table body. A connecting hose is connected to the intermediate chamber through the top cover, and an air pipe connector is connected to the top cover.

[0014] A further technical solution is to uniformly construct a plurality of coating holes at the lower end of the coating stage and to construct a plurality of culture chambers on the culture dish, with the culture chambers corresponding one-to-one with the coating holes.

[0015] A further technical solution is to install a liquid film maintaining member on each coating hole; the liquid film maintaining member includes multiple annular bodies arranged coaxially, and the multiple annular bodies are connected by multiple connecting ribs; or the liquid film maintaining member includes a volute body in the shape of a volute.

[0016] The technological advancements achieved by this invention compared to existing technologies, due to the aforementioned structure, lie in the following: The dual-piston dilution mechanism of this invention, through the mechanized control of a dual-piston drive mechanism, replaces the manual aspiration and release operations of a hand pipette, avoiding volume errors caused by human factors such as aspiration speed, release force, and liquid level reading deviations. Specifically, considering the characteristics of dairy products containing large molecules such as proteins and fats and having a viscous texture, the dual-piston drive mechanism can drive the dual-piston dilution mechanism to break up molecular aggregations in viscous samples through bidirectional actions of squeezing, circulating, and re-squeezing. Compared to manual shaking or unidirectional pushing, the mixing uniformity is significantly improved, completely solving the problems of difficult and time-consuming mixing in traditional manual dilution. After dilution is complete, the dual-piston drive mechanism can switch to transfer mode, precisely pushing the pre-mixed diluent within the dual-piston dilution mechanism to the multi-point coating mechanism at a fixed volume through a connecting tube. Compared to manual pipettes, which rely on operator readings and tip rinsing for quantification, the dual-piston driven mechanical quantification method has smaller errors (controllable within micro-level deviations) and ensures high consistency in the amount of diluent transferred across different batches, avoiding coating comparison errors caused by differences in transfer volume. The dual-piston drive mechanism simultaneously performs the functions of mixing and dilution and quantitative transfer, eliminating the need for an additional transfer mechanism. During the dilution stage, mixing is achieved by switching to dilution mode; during the transfer stage, the transfer mode is directly switched for quantitative delivery. This reduces the intermediate steps of changing pipettes and adjusting operator posture during manual transfer, making the dilution, transfer, and coating process smoother and significantly shortening the testing time per batch, making it particularly suitable for batch dairy product testing. During the dual-piston driven quantitative transfer process, the diluent always flows within a closed path formed by the dual-piston dilution mechanism, connecting tubing, and multi-point coating mechanism, without contact with the external environment, avoiding the risk of external contamination or cross-contamination. Simultaneously, it reduces direct contact between the operator and the sample, further reducing the risk of human contamination and ensuring the sterility of the testing environment. In summary, the present invention can effectively improve the efficiency and effect of dilution and coating, enhance the accuracy of the operation, and avoid external contamination. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0018] In the attached diagram: Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a structural schematic diagram from another angle of an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of the dual-plunger dilution mechanism according to an embodiment of the present invention; Figure 4This is an axial structural cross-sectional view of the dual-plunger dilution mechanism according to an embodiment of the present invention; Figure 5 This is a partial structural diagram of the horizontal dilution cylinder in the dual-plunger dilution mechanism of this invention. Figure 6 This is a partial structural cross-sectional view of the conductive adapter in the dual-plunger dilution mechanism of this invention. Figure 7 This is a schematic diagram of the structure of the dual-piston drive mechanism according to an embodiment of the present invention; Figure 8 This is an axial structural cross-sectional view of the dual-piston drive mechanism according to an embodiment of the present invention; Figure 9 This is a schematic diagram of the multi-point coating mechanism according to an embodiment of the present invention; Figure 10 This is a schematic diagram of the coating table in the multi-point coating mechanism of this invention. Figure 11 This is a schematic diagram of the coating table from another angle in the multi-point coating mechanism of this invention. Figure 12 This is a schematic diagram of the structure of the first liquid film maintaining member according to an embodiment of the present invention; Figure 13 This is a schematic diagram of the structure of the second type of liquid film maintaining member according to an embodiment of the present invention; Figure 14 This is a schematic diagram of the structure of the vertical guide rail, petri dish, and placement seat according to an embodiment of the present invention.

[0019] Components labeled: 100-Double plunger dilution mechanism, 101-Cylindrical body, 102-Constrictor nozzle, 103-Swirl channel, 104-Cylinder cover, 105-Inlet connector, 106-Plunger rod, 107-Moving plunger, 108-Assembly, 109-Connecting hole, 110-Vertical guide post, 111-First guide hole, 112-Second guide hole, 113-Connecting post, 114-Operating handwheel, 115-Sealing cover, 116-Connecting connector, 117-Support base, 200-Double piston drive mechanism, 201-Piston sleeve, 202-Piston rod, 20 3-Piston body, 204-First drive chamber, 205-Second drive chamber, 206-First connector, 207-Second connector, 208-Connecting cover, 209-Adapter arm, 300-Multi-point coating mechanism, 301-Base platform, 302-Top cover, 303-Air pipe connector, 304-Coating platform, 305-Coating hole, 306-Annular body, 307-Connecting rib, 308-Spiral body, 309-Linear motor, 310-Placement seat, 311-Vertical guide rail, 400-Connecting hose, 500-Cultural dish, 501-Dish body, 502-Cultural chamber. Detailed Implementation

[0020] The preferred embodiments of the present invention will now be described with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0021] This invention discloses a device for detecting the activity of dairy products, such as... Figures 1-14As shown, the system includes a dual-plunger dilution mechanism 100, a dual-piston drive mechanism 200, and a multi-point coating mechanism 300. The dual-plunger dilution mechanism 100 is mounted on a test bench, and the dual-piston drive mechanism 200 is mounted on one side of the dual-plunger dilution mechanism 100, with the two mechanisms connected in a transmission relationship. The multi-point coating mechanism 300 is located on the other side of the dual-plunger dilution mechanism 100. The outlet of the dual-plunger dilution mechanism 100 is connected to the inlet of the multi-point coating mechanism 300 via a connecting hose 400. An on / off valve is installed on the connecting hose 400, and a petri dish 500 is placed on the multi-point coating mechanism 300. The working principle and advantages of this invention are as follows: The dual-piston dilution mechanism 100 of this invention, through the mechanized control of the dual-piston drive mechanism 200, replaces the manual liquid aspiration and release operations of a hand pipette, avoiding volume errors caused by human factors such as aspiration speed, release force, and liquid level reading deviation. Specifically, considering the characteristics of dairy products containing large molecules such as proteins and fats and having a viscous texture, the dual-piston drive mechanism 200 can drive the dual-piston dilution mechanism 100 to break up the molecular aggregation of viscous samples through bidirectional actions of squeezing, circulating, and re-squeezing. Compared with manual shaking or pushing in one direction, the mixing uniformity is significantly improved, completely solving the problems of difficult and time-consuming mixing in traditional manual dilution. After dilution is completed, the dual-piston drive mechanism 200 can switch to transfer mode, precisely pushing the pre-mixed diluent in the dual-piston dilution mechanism 100 to the multi-point coating mechanism 300 through the connecting hose 400 at a fixed volume. Compared to manual pipettes, which rely on operator readings and tip rinsing for quantitative analysis, the dual-piston driven mechanical method has smaller quantitative errors (controllable within micro-level deviations) and ensures highly consistent transfer volumes across different batches, avoiding coating comparison errors caused by variations in transfer volume. The dual-piston drive mechanism 200 simultaneously performs both mixing and dilution and quantitative transfer functions, eliminating the need for an additional transfer mechanism. During the dilution stage, mixing is achieved by switching to dilution mode; during the transfer stage, the transfer mode is directly switched for quantitative delivery. This reduces the intermediate steps of changing pipettes and adjusting operator posture during manual transfer, making the dilution, transfer, and coating processes smoother and significantly shortening the testing time per batch, making it particularly suitable for batch dairy product testing. During the dual-piston driven quantitative transfer process, the diluent always flows within a closed path formed by the dual-piston dilution mechanism 100, the connecting tubing 400, and the multi-point coating mechanism 300, without contact with the external environment, avoiding the risk of external contamination or cross-contamination. Simultaneously, it reduces direct contact between the operator and the sample, further minimizing the risk of human contamination and ensuring the sterility of the testing environment. In summary, the present invention can effectively improve the efficiency and effect of dilution and coating, enhance the accuracy of the operation, and avoid external contamination.

[0022] As a preferred embodiment of the present invention, such asFigures 3-6 As shown, the dual-plunger dilution mechanism 100 includes two horizontal dilution cylinders arranged opposite each other. The two horizontal dilution cylinders are connected at their near ends by a conductive adapter, and the conductive adapter is connected to a connecting hose 400. A movable plunger 107 is installed inside each horizontal dilution cylinder. A plunger rod 106 is coaxially connected to the movable plunger 107. The plunger rod 106 extends movably from the end of the horizontal dilution cylinder away from the conductive adapter, and the plunger rod 106 is drively connected to the dual-piston drive mechanism 200. The horizontal dilution cylinder of this embodiment includes a cylindrical body 101 with a support base 117 fixed at its lower part. A constriction nozzle 102 is coaxially constructed at one end of the cylindrical body 101 near the conductive adapter. A cylinder cover 104 is detachably connected to the other end of the cylindrical body 101. An inlet connector 105 is connected to the upper part of the peripheral wall of the cylindrical body 101 near the cylinder cover 104. In this embodiment, the movable plunger 107 has a frustum-shaped structure. When the movable plunger 107 is located inside the constrictor 102, it fits into the inner cavity of the constrictor 102. Multiple swirling grooves 103 are spaced circumferentially on the inner wall of the constrictor 102, each extending from the large-diameter end of the constrictor 102 to the connecting connector. The connecting connector in this embodiment includes an assembly 108 and a vertical guide post 110. The assembly 108 is constructed at the connection of two horizontal dilution cylinders, and a sealing cap 115 is detachably connected to the lower end of the assembly 108. The vertical guide post 110 is rotatably connected inside the assembly 108, and a connecting post 113 is constructed at the lower end of the vertical guide post 110. An operating handwheel 114 is mounted at the lower end of the connecting post 113. The assembly 108 has a connecting hole 109 that connects two horizontal dilution cylinders. The vertical guide post 110 has a first guide hole 111 that connects the two horizontal dilution cylinders through the connecting hole 109. The vertical guide post 110 also has a second guide hole 112 that connects to the first guide hole 111. The assembly 108 has a connecting connector 116 that connects the second guide hole 112 to the connecting hose 400.

[0023] In this embodiment, two horizontally arranged dilution cylinders are connected by a conductive adapter. Combined with the movable plunger 107 driven by the dual-piston drive mechanism 200, bidirectional circulation of liquid between the two cylinders is achieved. When the movable plunger 107 on one side advances and the movable plunger 107 on the other side retracts, the diluent is pushed from one horizontal dilution cylinder to the conductive adapter and then flows into the other horizontal dilution cylinder; in the reverse operation, the liquid flows back, forming a compression-flow-re-compression cycle. This bidirectional flow design, compared to unidirectional mixing in a single container, can more thoroughly agitate dairy product samples (containing viscous components such as proteins and fats), breaking down large molecular aggregates and ensuring uniform mixing of the sample and diluent, thus solving the defects of incomplete mixing and local concentration deviations in traditional dilution methods. The movable plunger 107 precisely matches the inner cavity of the cylindrical body 101 of the horizontal dilution cylinder, and the plunger rod 106 is rigidly connected to the dual-piston drive mechanism 200. The quantitative stroke of the dual-piston drive mechanism 200 can be directly converted into the pushing / drawing volume of the movable plunger 107. Compared to manual pipetting which relies on visual readings, this mechanically driven volume control method avoids human error in liquid aspiration and release, providing a foundation for the accuracy of subsequent dilution concentrations. In this embodiment, the inlet connector 105 on the upper part of the cylindrical body 101 is located close to the cap 104, eliminating the need to disassemble other parts when adding samples or diluents, making operation convenient. Furthermore, the position design of the inlet connector 105 prevents liquid overflow during addition and reduces air residue. The removable cap 104 facilitates subsequent cleaning and disinfection of the horizontal dilution cylinder, preventing bacterial growth from residual samples that could affect subsequent test results and extending the device's lifespan.

[0024] In this embodiment, the constriction nozzle 102 at the end of the cylindrical body 101 has a tapered structure, and the frustum-shaped movable plunger 107 is precisely fitted to the inner cavity of the constriction nozzle 102. When the movable plunger 107 is pushed towards the constriction nozzle 102, the liquid inside the cylindrical body 101 is squeezed into the narrow channel of the constriction nozzle 102, the flow rate increases instantaneously, and a strong shearing force is formed, which can effectively tear apart viscous clumps in the dairy product sample and promote the molecular-level fusion of the sample and the diluent. When the movable plunger 107 is retracted, the constriction nozzle 102 forms a negative pressure suction force, which can smoothly draw in the liquid from another cylindrical body 101, avoiding volume errors caused by turbulence. Multiple swirling grooves 103 on the inner wall of the constriction nozzle 102 cause the liquid flowing through the constriction nozzle 102 to form a spiral turbulent flow along the grooves. During the spiral flow of the liquid, centrifugal force and radial stirring force are generated, which not only further disperses incompletely mixed viscous particles, but also allows the sample and diluent to fully interweave during the flow. Compared with straight flow, the mixing effect is significantly improved, ultimately ensuring uniform concentration of the diluent and avoiding distortion of test results due to insufficient local mixing. Therefore, the fitting design of the frustum-shaped movable plunger 107 and the constricting nozzle 102 in this embodiment not only creates a squeezing effect during advancement, but also achieves a tight seal during the stationary or transfer phases (for constricting nozzles 102 without swirling grooves 103). Compared with a cylindrical plunger, the frustum-shaped structure has a larger contact area with the gradually narrowing constricting nozzle 102, resulting in a better sealing effect. This prevents liquid leakage from the gap between the plunger and the cylinder wall during dilution or transfer, ensuring the accuracy of quantitative transfer. Simultaneously, this fitting structure reduces the frictional resistance of the movable plunger 107 during movement, reduces mechanical loss, and improves the transmission efficiency of the dual-piston drive mechanism 200.

[0025] The multi-functional design of the conductive adapter in this embodiment balances operational flexibility with transmission sealing. The vertical guide column 110 can be flexibly rotated via the operating handwheel 114 to switch between two working modes. ① Mixing mode: Rotating the vertical guide column 110 aligns the first guide hole 111 with the connecting hole 109 of the assembly 108, connecting only the two horizontal dilution cylinders (this is the dilution mode of the dual-piston drive mechanism 200), ensuring that the liquid circulates and mixes between the two cylinders without being transported to the coating mechanism; ② Transfer mode: Rotating the operating handwheel 114 connects the first guide hole 111 with the second guide hole 112. At this time, the diluent in the two horizontal dilution cylinders can enter the connecting hose 400 through the first guide hole 111, the second guide hole 112, and the connecting connector 116 (this is the transfer mode of the dual-piston drive mechanism 200), realizing quantitative transfer to the multi-point coating mechanism 300. This switchable design eliminates the need for disassembly or component replacement, facilitating operation and preventing leakage or premature transfer of the diluent during mixing, ensuring process continuity. The assembly 108 of the connecting connector forms a closed fit with the vertical guide column 110 and sealing cap 115, and the horizontal dilution cylinder is sealed by the cap 104 (a detachable design facilitates cleaning). The entire dilution process is completed within a closed space. The liquid flow path has no exposed links, preventing contamination from external air and impurities, and preventing losses due to diluent leakage, ensuring sample sterility and accurate dilution volume. The vertical guide column 110 is connected to the operating handwheel 114 via the connecting column 113, allowing operators to precisely control the switching process. The switching process is smooth and accurate, avoiding liquid stagnation or pressure fluctuations caused by poor flow. Simultaneously, the integrated structure of the assembly 108 and the horizontal dilution cylinder ensures a stable connection, reducing structural loosening during long-term use and guaranteeing the stability of the dilution and transfer process.

[0026] As a preferred embodiment of the present invention, such as Figure 2 , Figure 7 , Figure 8As shown, the dual-piston drive mechanism 200 includes a piston sleeve 201, two piston bodies 203, and two piston rods 202. The axis of the piston sleeve 201 is parallel to the axis of the horizontal dilution cylinder, and connecting caps 208 are detachably connected to both ends of the piston sleeve 201. The two piston bodies 203 are axially spaced within the piston sleeve 201, with their ends coaxially connected to corresponding piston rods 202. Each piston rod 202 extends movably from its corresponding connecting cap 208 and is connected to a corresponding movable plunger 107 via an adapter arm 209. In this embodiment, a first driving cavity 204 is formed inside the piston sleeve 201 and between the two piston bodies 203, and a second driving cavity 205 is formed inside the piston sleeve 201 and between the piston body 203 and the corresponding connecting cover 208. A first connector 206 is connected in the middle of the first driving cavity 204, and a second connector 207 is connected in the second driving cavity 205 near the connecting cover 208.

[0027] This embodiment independently controls the pressure of the two second drive chambers 205 (e.g., pressurizing only the left second drive chamber 205 and maintaining / releasing pressure in the right second drive chamber 205), which drives the two piston bodies 203 to move in the same direction (e.g., both to the right). If the two piston bodies 203 move to the right synchronously, the left piston body 203 advances, pushing the liquid out of the left horizontal dilution cylinder, while the right piston body 203 advances, creating a negative pressure for liquid aspiration in the right horizontal dilution cylinder. This unidirectional movement mode overcomes the limitation of only being able to simultaneously aspirate and discharge from both cylinders, enabling independent liquid aspiration from a single cylinder, such as adding a sample to the right cylinder and adding diluent to the left cylinder; or quantitative liquid discharge from a single cylinder, such as transferring a portion of the mixed diluent from the left cylinder to the right cylinder for later use. It is particularly suitable for stepwise dilution scenarios, such as completing primary dilution in a single cylinder and then transferring it to another cylinder for secondary dilution through unidirectional movement, improving the flexibility and accuracy of the dilution operation.

[0028] When pressure is applied to both second drive chambers 205 simultaneously, the two piston bodies 203 are driven to move closer together (in opposite directions). This synchronously propels the movable plungers 107 on both sides toward the constriction nozzle 102 of the horizontal dilution cylinder, squeezing the liquid in both cylinders to the conductive adapter. Combined with the swirling groove 103 of the constriction nozzle 102, the liquid forms strong turbulence at the confluence, accelerating the mixing of the sample and diluent. If the conductive adapter switches to transfer mode at this time, the continuous pressure generated by the opposite movement can quantitatively push the mixed diluent to the multi-point coating mechanism 300. Compared with single piston body 203 drive, the pressure of the opposite compression of the two piston bodies 203 is more stable, the discharge speed is uniform, and liquid residue caused by insufficient pressure is avoided, ensuring the accuracy of transfer volume. When pressure is applied to the first drive chamber 204 (between the two piston bodies 203), the two piston bodies 203 are driven to move away from each other (moving in opposite directions). This simultaneously drives the movable plungers 107 on both sides to retract, creating a negative pressure inside the dual horizontal dilution cylinder. Samples and diluents are then rapidly drawn in through the inlet connector 105. This mode is suitable for batch dilution scenarios, allowing equal or different amounts of liquid to be drawn into both cylinders at once (by controlling the aspiration time or pressure). Compared to single-cylinder aspiration in stages, efficiency is significantly improved, and simultaneous aspiration from both cylinders reduces the risk of contamination caused by operation intervals.

[0029] In this embodiment, the first driving chamber 204 and the two second driving chambers 205 on both sides are connected to a pressure source via independent connectors (first connector 206, second connector 207 on the left, and second connector 207 on the right), allowing for individual adjustment of the pressure and pressurization rate of each chamber. When controlling unidirectional movement, the pressure difference between the two second driving chambers 205 is adjusted by differential adjustment (e.g., the pressure on the left is greater than that on the right), precisely controlling the speed difference of the two piston bodies 203 in the same direction (e.g., the left side advances faster, the right side advances slower), achieving coordinated operation of quantitative liquid discharge from one cylinder and quantitative liquid aspiration from the other. When controlling opposite / reverse movement, the pressure of the corresponding chambers is adjusted synchronously to ensure consistent movement speeds of the two piston bodies 203, avoiding uneven liquid mixing or differences in transfer volume caused by speed deviations.

[0030] As a preferred embodiment of the present invention, such as Figures 9-14As shown, the multi-point coating mechanism 300 includes a coating stage, a placement seat 310, two linear motors 309, and two vertical guide rails 311. The two linear motors 309 are symmetrically mounted on both sides of the coating stage, the placement seat 310 is located below the coating stage, and the two vertical guide rails 311 are symmetrically mounted on both sides of the placement seat 310. Each linear motor 309 is connected to the corresponding vertical guide rail 311. The petri dish 500 is placed on the placement seat 310, and the coating stage is connected to the connecting hose 400. In this embodiment, the coating stage includes a top cover 302, a base platform 301, and a coating stage 304 connected vertically downwards. An intermediate chamber is formed within the base platform 301, and a coating chamber communicating with the intermediate chamber is formed within the coating stage 304. The connecting hose 400 communicates with the intermediate chamber through the top cover 302, and an air pipe connector 303 is connected to the top cover 302. In this embodiment, a plurality of coating holes 305 are uniformly constructed at the lower end of the coating stage 304. The culture dish 500 includes a dish body 501, on which a plurality of culture chambers 502 are constructed, and the culture chambers 502 are arranged one-to-one with the coating holes 305. In this embodiment, a liquid film maintaining member is installed on each coating hole 305, and the liquid film maintaining member has two structures. The first type is that the liquid film maintaining member includes a plurality of coaxially arranged annular bodies 306, which are connected by a plurality of connecting ribs 307, with the outermost annular body 306 connected to the coating hole 305. The second type is that the liquid film maintaining member includes a spiral-shaped spool body 308, the outer end of which is connected to the coating hole 305. The function of the liquid film maintainer is to maintain the diluent in the form of a liquid film at the coating hole 305, and the size of the coating hole 305 is adapted to the size of the culture chamber 502, so that after the liquid film comes into contact with the culture medium in the culture chamber 502, it can be evenly coated on the culture medium.

[0031] In this embodiment, multiple coating wells 305 are evenly arranged at the lower end of the coating platform 304, precisely aligned with multiple culture chambers 502 on the petri dish 500. Diluent can be synchronously injected into the corresponding culture chamber 502 through all coating wells 305, replacing the traditional manual single-well / single-plate coating operation. This is particularly suitable for batch dairy product testing scenarios, such as factory batch quality inspection, significantly reducing the overall testing process time. The diluent for all coating wells 305 originates from the same intermediate chamber and coating chamber, quantitatively pushed by a dual-piston drive mechanism 200, ensuring that the liquid volume and flow rate of each coating well 305 are completely consistent. Simultaneously, synchronous coating avoids the differences caused by environmental changes (such as temperature and humidity) between coatings applied before and after manual operation, ensuring uniform coating conditions across multiple culture chambers 502, reducing batch testing errors, and improving result repeatability.

[0032] The two liquid film maintaining components in this embodiment serve to disperse the surface tension of the diluent when it is located in the coating hole 305, preventing the diluent from forming large droplets and dripping. This ensures that the diluent forms a very stable and uniform liquid film at the coating hole 305, so that the liquid film guided by the liquid film maintaining components can precisely cover the surface of the culture medium in the culture chamber 502.

[0033] In this embodiment, the linear motors 309 on both sides of the coating stage are connected to the vertical guide rails 311 of the placement seat 310, which can drive the coating stage to move up and down precisely vertically. Before coating, the linear motors 309 drive the coating stage to descend, so that the coating hole 305 is precisely aligned with the culture chamber 502 (or maintains a fixed small gap), avoiding alignment deviations caused by manual placement of the coating stage. After coating, the coating stage automatically rises, making it easy to remove the culture dish 500. The entire process does not require manual adjustment of the position, and the alignment accuracy can be controlled within millimeters, which is far higher than the error range of manual operation. The automated lifting and lowering replaces the manual action of hand-held coating, avoiding the problems of excessive force damaging the culture medium or insufficient force causing alignment deviations in manual operation. At the same time, the uniform speed transmission of the linear motors 309 ensures that the lifting and lowering of the coating stage is smooth, and the diluent will not be spilled or the liquid film will be broken due to vibration, ensuring the stability of the coating process and reducing repeated experiments due to operational errors.

[0034] In this embodiment, the intermediate chamber of the base platform 301 and the coating chamber of the coating platform 304 form a two-stage buffer structure: the diluent first enters the intermediate chamber for initial pressure stabilization and uniform distribution, and then flows into the coating chamber for further dispersion to each coating hole 305. This avoids the problem of higher liquid volume in coating holes 305 near the inlet and lower liquid volume in those farther from the inlet due to pressure fluctuations during delivery via the connecting hose 400, ensuring that the output liquid volume of all coating holes 305 is absolutely consistent and improving coating uniformity. The diluent enters the intermediate chamber and coating chamber from the connecting hose 400, and then is injected into the culture chamber 502 through the coating holes 305. The entire flow path is completely closed and does not come into contact with outside air, avoiding external contamination or cross-contamination caused by the exposure of the coater and the openness of the culture dish 500 during manual coating. The endotracheal connector 303 on the top cover 302 can be connected to a sterile gas source, which assists the flow of the diluent by slightly pressurizing it, while preventing outside air from being drawn back into the intermediate chamber, further ensuring the sterility of the sample and ensuring that the test results are not affected by contamination.

[0035] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A device for detecting the activity of dairy products, characterized in that: The device includes a dual-plunger dilution mechanism mounted on a test bench, which is connected to a dual-piston drive mechanism mounted on one side of the dual-plunger dilution mechanism. A multi-point coating mechanism is provided on the other side of the dual-plunger dilution mechanism. The outlet end of the dual-plunger dilution mechanism is connected to the inlet end of the multi-point coating mechanism via a connecting hose. An on / off valve is installed on the connecting hose. A petri dish is placed on the multi-point coating mechanism.

2. The dairy product activity detection device according to claim 1, characterized in that: The dual-plunger dilution mechanism includes two horizontal dilution cylinders arranged opposite each other. The two horizontal dilution cylinders are connected at their close ends via a conductive adapter, and the conductive adapter is connected to a connecting hose. A movable plunger is assembled inside each horizontal dilution cylinder. A plunger rod connected to the movable plunger extends movably from the end of the horizontal dilution cylinder away from the conductive adapter, and the plunger rod is connected to a dual-piston drive mechanism.

3. The dairy product activity detection device according to claim 2, characterized in that: The horizontal dilution cylinder includes a cylindrical body, with a constriction nozzle coaxially constructed at one end of the cylindrical body near the conductive adapter, and a cylinder cap detachably connected to the other end of the cylindrical body. An inlet connector is connected to the upper part of the peripheral wall of the cylindrical body near the cylinder cap. The movable plunger has a frustum-shaped structure, and when the movable plunger is located inside the constriction nozzle, the movable plunger is adapted to the inner cavity of the constriction nozzle.

4. The dairy product activity detection device according to claim 3, characterized in that: Multiple swirling grooves are spaced apart circumferentially on the inner wall of the constricting nozzle, and each swirling groove extends from the large-diameter end of the constricting nozzle to the conductive adapter.

5. The dairy product activity detection device according to claim 2, characterized in that: The conductive adapter includes an assembly constructed at the connection of two horizontal dilution cylinders, a vertical guide post rotatably connected to the assembly, a connecting hole for connecting the two horizontal dilution cylinders on the assembly, a first guide hole for connecting the two horizontal dilution cylinders through the connecting hole on the vertical guide post, and a second guide hole for communicating with the first guide hole on the vertical guide post. The second guide hole is connected to a connecting hose.

6. The dairy product activity detection device according to claim 2, characterized in that: The dual-piston drive mechanism includes a piston sleeve parallel to the axis of the horizontal dilution cylinder. Connecting caps are detachably connected to both ends of the piston sleeve. Two piston bodies are axially spaced inside the piston sleeve. Piston rods are connected to the ends of the two piston bodies that are far apart from each other. Each piston rod extends out of its corresponding connecting cap and is connected to a corresponding movable plunger through an adapter arm. A first drive chamber is formed inside the piston sleeve between the two piston bodies. A second drive chamber is formed inside the piston sleeve between the piston bodies and the corresponding connecting caps. A first connector is connected to the middle of the first drive chamber, and a second connector is connected to the second drive chamber near the connecting cap.

7. The dairy product activity detection device according to claim 1, characterized in that: The multi-point coating mechanism includes a coating table with linear motors symmetrically mounted on both sides, a placement seat below the coating table, and vertical guide rails symmetrically mounted on both sides of the placement seat. Each linear motor is connected to the corresponding vertical guide rail for transmission. The culture dish is placed on the placement seat, and the coating table is connected to a connecting tubing.

8. The dairy product activity detection device according to claim 7, characterized in that: The coating table includes a top cover, a base platform, and a coating table body connected vertically downwards in sequence. An intermediate chamber is formed in the base platform body, and a coating chamber communicating with the intermediate chamber is formed in the coating table body. A connecting hose is connected to the intermediate chamber through the top cover, and an air pipe connector is connected to the top cover.

9. The dairy product activity detection device according to claim 8, characterized in that: Multiple coating holes are uniformly constructed at the lower end of the coating stage, and multiple culture chambers are constructed on the culture dish, with the culture chambers corresponding to the coating holes one by one.

10. The dairy product activity detection device according to claim 9, characterized in that: A liquid film maintaining member is installed on each coating hole; the liquid film maintaining member includes a plurality of annular bodies arranged coaxially, and the plurality of annular bodies are connected by a plurality of connecting ribs; or the liquid film maintaining member includes a volute body in the form of a volute.

Images