Pet urine multi-channel synchronous detection card and method

Abstract

The application discloses a pet urine multi-channel synchronous detection card and method, and belongs to the technical field of microfluidic detection. The card adopts a liquid injection microfluidic framework with hierarchical patterns, realizes uniform wettability and synchronous flow in parallel microchannels through the combination of biomimetic micro / nano hierarchical structure and liquid injection porous coating (LIPC). The design simulates the anisotropic wetting characteristics of bamboo leaves, prepares periodic microgrooves and nano pillar arrays on the surface of polydimethylsiloxane (PDMS) channels, and stabilizes the wettability through fluoropolymer injection into the porous matrix to form a super slippery surface (SLIPS), which significantly reduces the contact angle hysteresis. The technology utilizes capillary action to drive the synchronous flow of urine samples in multiple channels, avoids cross contamination, ensures uniform dispersion of gold standard nanoparticles and synchronous formation of detection lines / control lines. The system completes multi-index detection within 10 minutes, and the flow rate variation coefficient between channels is less than 5%, which is suitable for large-scale production of disposable detection cards.

Description

Technical Field

[0001] This invention belongs to the field of microfluidic detection technology, specifically a multi-index simultaneous detection device for pet urine based on biomimetic micro / nano structures. This technology combines the wetting regulation characteristics of micro / nano hierarchical structures on biological surfaces with the super-lubricating properties of liquid-injected porous coatings to solve problems such as flow rate differences and asynchronous detection signals caused by uneven wetting in multi-channel microfluidic detection cards. Background Technology

[0002] Most existing pet urine testing products use single-channel test strips or simple parallel detection structures. In multi-channel detection structures, the wetting state and flow resistance of urine in different channels often vary due to factors such as material surface energy, roughness, processing errors, and differences in sample composition, resulting in flow rate differences. These flow rate differences directly lead to the following problems:

[0003] The color development time varies for different detection indicators;

[0004] Inconsistent reaction conditions in the detection line can affect the accuracy of quantitative or semi-quantitative analysis.

[0005] It can even create a risk of cross-contamination between adjacent passages.

[0006] Existing methods, such as plasma treatment, chemical modification, or simply changing the channel size, cannot maintain a stable synchronous flow effect during long-term storage and actual use, and therefore cannot meet the needs of simultaneous detection of multiple indicators in pet urine. Summary of the Invention

[0007] The purpose of this invention is to provide a pet urine detection card with a simple structure, no external drive required, and capable of stably realizing multi-channel synchronous flow, so as to solve the problem of asynchronous multi-channel detection in the prior art.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] Pet urine multi-channel simultaneous detection card, including:

[0010] Sample loading area, used to receive pet urine samples;

[0011] A microfluidic detection channel array, comprising multiple microfluidic detection channels arranged in parallel and isolated from each other;

[0012] A biomimetic micro / nano hierarchical structure is disposed on at least a portion of the inner surface of each of the microfluidic detection channels;

[0013] A liquid-injected porous coating is applied to the surface of the biomimetic micro / nano hierarchical structure.

[0014] The detection area is connected to each of the microfluidic detection channels and is used to generate detection signals;

[0015] The biomimetic micro / nano hierarchical structure is used to guide urine to spread in a predetermined direction at the geometric level, and the liquid-injected porous coating is used to reduce the contact angle hysteresis of urine on the inner surface of the channel and weaken the interfacial adhesion resistance. The two work together to enable urine samples to flow synchronously in multiple microfluidic detection channels under capillary force without external driving conditions, thereby achieving synchronous detection of multiple indicators.

[0016] The core module is a PDMS microchannel array with hierarchical micro / nano structures. The inner surface of each channel is fabricated using photolithography and reactive ion etching (RIE) to create a periodic microgroove structure resembling bamboo leaves. Specific parameters include: groove width... ,depth ,spacing Orientation angle of microgrooves Arranged along the channel axis ( Directional capillary flow is achieved by adjusting geometric parameters. Further machining of the microgroove surface using RIE (Reverse Engineering) is then performed to create a diameter... ,high The array of nanopillars forms a secondary rough structure.

[0017] The wetting behavior of this structure is described by the modified Washburn equation:

[0018] in Let be the displacement of the wetting front at time t. The surface tension of urine (approximately 70 mN / m). The equivalent contact angle (modulated by the microgroove geometry). The dynamic viscosity of urine is approximately 0.7 mPa·s. Microgrooves increase axial capillary force by 3.2 times (compared to planar channels) by restricting lateral liquid spread, while nanopillar arrays increase contact angle hysteresis from conventional PDMS by enhancing the solid-liquid contact line pinning effect. Down to .

[0019] Liquid-injected porous coating (LIPC): A 20% w / v PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene copolymer) acetone solution is spin-coated onto the surface of a micro / nano structure, followed by aqueous-phase induced phase separation to form a three-dimensional interpenetrating network with a pore size of approximately 100 nm. Subsequently, a perfluoropolyether (PFPE) lubricant is infused under vacuum conditions, with a viscosity... Surface tension The lubricant forms a continuous thin film in the pores, the thickness of which is... satisfy:

[0020] in For the injection volume, Pore ​​specific surface area (approximately) ), The porosity is 65%. This coating further reduces the contact angle hysteresis to [value missing]. And it suppresses the difference in flow velocity between channels through the following mechanisms:

[0021] Viscosity ratio control: surface viscosity Bulk viscosity ratio Reduce boundary slip resistance;

[0022] Pressure equalization: capillary pressure in porous matrices ( Where is the pore radius, It provides self-healing capability for the lubricant contact angle, and automatically compensates for pressure differences through lubricant redistribution when local wettability changes.

[0023] Synchronous Flow Control Module: To achieve flow velocity synchronization in 8-12 parallel channels, the system incorporates a conical flow splitting structure at the channel inlet, with an expansion angle of [missing information]. satisfy:

[0024] in For total flow, and These are the inlet and outlet radii of the conical structure, respectively. It has a tapered length. This design reduces the flow rate difference between branch channels from 18% in a traditional T-type splitter to 4.7%.

[0025] Biomolecular compatibility treatment: Grafting polyethylene glycol (PEG) brush-like molecular layers (molecular weight 2000 Da) onto the LIPC surface, with a grafting density of... Characterized by XPS, the PEG layer thickness is 0.8 chains / nm². Estimated using the following empirical formula:

[0026]

[0027] This treatment reduced the non-specific adsorption of urinary proteins (such as albumin and globulin) by 92% while maintaining the activity of the gold-labeled antibody (with a titer loss of <5%).

[0028] Signal coupling interface: A gradient pore size transition layer is set at the junction of the nitrocellulose membrane and the microchannel: 3 μm pore size near the channel side (to ensure capillary continuity), and 8 μm pore size near the membrane side (to match traditional LFA membranes). Transition layer length. Optimization based on the Washburn-Rideal equation:

[0029]

[0030] in , These are the average apertures on both sides, The allowable flow delay time is set to <2 seconds. This design keeps the color development time difference of the detection lines within 6 seconds (corresponding to CV <3%).

[0031] Methods for simultaneous multi-indicator testing of pet urine using a test card, including...

[0032] Load the urine sample into the sample loading area;

[0033] Through the synergistic effect of biomimetic micro / nano hierarchical structures and liquid-injected porous coatings, urine is synchronously flowed in multiple microfluidic detection channels under capillary force.

[0034] Multiple detection signals corresponding to different detection indicators are generated in the detection area and interpreted synchronously.

[0035] The time difference between urine flow completion in multiple microfluidic detection channels is less than a preset threshold, ensuring that the detection results of each indicator are comparable.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] 1. Enables simultaneous flow of urine samples from multiple channels, resulting in high detection consistency;

[0038] 2. No external drive device required, simple structure, suitable for disposable test cards;

[0039] 3. Stable wetting properties, adaptable to different urine compositions;

[0040] 4. It can detect multiple urine indicators simultaneously, making it suitable for home and clinical use. Attached Figure Description

[0041] Figure 1 This is a structural diagram of the biomimetic microfluidic channel system for the pet urine multi-index detection card of the present invention;

[0042] Figure 2 This is a schematic diagram of the microstructure of the liquid-injected porous coating (LIPC) of the present invention;

[0043] Figure 3 This is a schematic diagram of the multi-channel synchronous flow control principle of the present invention; Detailed Implementation

[0044] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0045] Figure 1 middle

[0046] Sample processing module: Responsible for the initial filtration and processing of urine samples.

[0047] Sample pad: Receives and initially absorbs urine samples.

[0048] Glass fiber filter membrane: Removes suspended particles and impurities from samples.

[0049] Bionic microfluidic channel: the core module of this invention

[0050] Microgroove array: a periodic structure 20μm wide and 10μm deep, guiding the directional flow of liquid.

[0051] Nanopillar structure: Nanoscale roughness with a diameter of 200 nm enhances capillary effect.

[0052] PVDF-HFP porous matrix: a three-dimensional network structure with 65% porosity.

[0053] PFPE lubricating layer: forms a super-lubricating interface, reducing flow resistance.

[0054] Detection module: Completes the capture and signal detection of the target analyte.

[0055] Gold-labeled binding pad: Releases labeled antibody

[0056] Nitrocellulose membrane: used to fix detection and control lines.

[0057] Absorbent pad: Provides capillary drive.

[0058] The biomimetic microfluidic channel module achieves synchronous flow control across multiple channels through the synergistic effect of a microgroove / nanopillar hierarchical structure and a liquid-injected porous coating, solving the problem of flow rate differences caused by uneven wettability in traditional designs.

[0059] Figure 2 middle

[0060] Coating Structure: Composition and Hierarchical Structure of LIPC

[0061] PDMS substrate: The basic material for microfluidic channels

[0062] Microgrooves: Oriented structures at the macroscale

[0063] Nanopillars: Nanoscale surface roughness

[0064] PVDF-HFP matrix: porous support structure

[0065] PFPE lubricant: forms a continuous lubricating layer

[0066] Liquid behavior: Flow characteristics of urine on coated surfaces

[0067] Urine sample: Test sample

[0068] Super-smooth interface: Surface with extremely low contact angle hysteresis

[0069] Low-resistance flow: a uniform and stable flow state

[0070] This coating creates a self-healing, super-lubricating interface through the synergistic effect of micro-nano composite structures and fluorinated polymers. Its surface viscosity ratio and capillary pressure equalization mechanism provide a physical basis for multi-channel synchronous flow control.

[0071] Figure 3 middle

[0072] Flow control: Multi-channel split design

[0073] Conical splitter structure: Optimized design with an 8° expansion angle

[0074] Channels 1-4: Parallel detection channels

[0075] Synchronization mechanism: Ensures consistent flow rate across all channels.

[0076] Uniform flow velocity: The flow fronts of each channel advance synchronously.

[0077] By designing a tapered flow splitter structure with specific geometric parameters, the flow difference between multiple channels is reduced from 18% in traditional designs to 4.7%, achieving true simultaneous detection of multiple indicators.

[0078] Example 1

[0079] A flexible detection card variant suitable for non-planar applications. Traditional rigid PDMS microchannels are replaced with a polyurethane (PU) elastomer substrate, and a bamboo leaf microgroove structure (groove width adjustable from 15-25 μm) is replicated on its surface using nanoimprinting technology. The LIPC coating uses a flexible fluorinated acrylate copolymer instead of PVDF-HFP, maintaining porosity while improving bending resistance (withstanding 500 cycles of 180° bending). The channel array uses a serpentine arrangement instead of a straight design, with a bending radius ≥5 mm, ensuring that the liquid maintains synchronous flow velocity in each channel (CV <7%) even when bent. This design is particularly suitable for integration with pet pee pads or wearable monitoring devices.

[0080] Example 2

[0081] This multi-level wetting gradient channel design is specifically for high-viscosity urine samples (such as dehydrated pets). In this embodiment, a three-level wetting gradient is constructed within a single channel: the inlet section uses dense microgrooves (20 μm spacing) with a 1:1 aspect ratio combined with high-porosity LIPC (75%) to enhance initial wetting; the middle section transitions to a medium-density groove (30 μm spacing) and standard LIPC (65%); the outlet section uses a sparse groove (50 μm spacing) combined with low-porosity LIPC (55%) to balance flow rate and detection reaction time. The sections are smoothly transitioned through a conical structure to avoid abrupt interface changes. Experiments show that this design can improve the flow synchronicity of high-viscosity samples (η=1.2 mPa·s) to CV<6%, while the traditional single-level structure achieves CV of 15%.

[0082] Example 3

[0083] This detachable modular detection card, designed to accommodate different combinations of detection indicators, features a modular design: a basic flow control module comprising an 8-channel biomimetic microfluidic unit and a LIPC coating, with standardized interface dimensions; replaceable detection modules including pre-coated nitrocellulose membrane assemblies for different indicators such as glucose and protein; and a magnetic coupling interface with a magnetic sealing ring (NdFeB magnetic ring + fluororubber) on the module mating surface, ensuring liquid sealing (leakage rate <0.5 μL / min) while facilitating manual replacement. Users can combine 2-4 detection modules as needed, and the system matches flow rate parameters using automatic channel identification technology (each module includes an RFID tag).

[0084] Example 4

[0085] Environmentally responsive LIPC coatings: This embodiment develops a temperature / pH dual-responsive LIPC coating.

[0086] Thermosensitive phase change lubricant: It uses a mixture of perfluoropolyether and n-octadecane (7:3 ratio) to maintain a liquid state within the normal body temperature range of pets (38-39℃), and partially crystallizes at room temperature (25℃) to lock the flow front position;

[0087] pH-responsive pore structure: Dimethylaminoethyl methacrylate (DMAEMA) copolymer is added to the porous matrix, causing the pores to expand by 15% when the urine pH is >7, automatically compensating for changes in surface tension in alkaline urine. This design allows the test card to maintain flow rate stability (ΔCV < 2%) under ambient temperature fluctuations of 4-40℃.

[0088] Example 5

[0089] This embodiment proposes a low-cost injection molding solution for large-scale production needs:

[0090] Micro-nano integrated mold: The nickel template is processed by laser interference lithography, which contains a negative structure of microgrooves (20 μm) and nanoparticles (200 nm), and the PC-based microchannel is formed in one step by micro-injection molding process;

[0091] In-situ LIPC formation technology: Fluorinated silica nanoparticles (20 nm, 5% wt) are premixed into the injection molding raw material as a pore-forming agent. After injection molding, the material is treated with supercritical CO2 to form interconnected pores, followed by vacuum injection of lubricant. This process reduces production costs by 60% while maintaining consistent wettability between channels (contact angle variation <3°).

[0092] Example 6

[0093] This embodiment integrates sample preprocessing functionality, which is located in the microchannel inlet area:

[0094] Size exclusion filter membrane: 3D printed gradient pore structure (top layer 50 μm, middle layer 20 μm, bottom layer 5 μm), directly bonded to PDMS channel;

[0095] Online dilution chamber: The dilution ratio (adjustable from 1:1 to 1:5) is controlled via a serpentine mixing channel and a LIPC-modified capillary valve (sudden expansion structure), avoiding manual dilution operations. Testing shows that this design can effectively process hematuria samples with red blood cell counts >50 / μL without affecting the sensitivity of subsequent detections.

[0096] Example 7

[0097] Taking a four-channel pet urine test card as an example, the performance of the traditional design and the present invention in the simultaneous detection of glucose, protein, ketones, and pH was compared: In the traditional unmodified nitrocellulose channel, the completion time of each channel varied significantly (glucose channel 8 minutes 15 seconds, protein channel 9 minutes 40 seconds, ketones channel 7 minutes 50 seconds, pH channel 10 minutes 20 seconds), and false positive bands appeared in the glucose detection area due to protein diffusion. After adopting the LIPC-modified channel of the present invention, the flow completion time of the four channels was concentrated between 9 minutes 55 seconds and 10 minutes 05 seconds (CV=3.8%), the color intensity of the detection lines was consistent, there was no cross-contamination, and all results could be clearly interpreted at 10 minutes. This example verifies that the synergistic effect of the biomimetic micro / nano structure and the liquid injection coating can eliminate the flow rate differences of multiple channels and ensure the synchronicity and accuracy of multi-index detection.

[0098] The pet urine multi-channel synchronous detection card of this invention achieves flow rate synchronization and signal consistency for multi-index detection through an innovative combination of biomimetic micro-nano structures and liquid injection porous coatings. Its technical advantages are specifically reflected in the following aspects:

[0099] Breakthrough in flow control performance: The bamboo leaf-inspired microgroove / nanopillar hierarchical structure increases axial capillary force by 3.2 times. Combined with the super-slippery properties of the LIPC coating (contact angle hysteresis <5°), the coefficient of variation (CV) of the flow rate in 8-12 parallel channels is stably controlled below 5%, solving the problem of asynchronous detection caused by wettability differences in traditional multi-channel microfluidic systems.

[0100] Biocompatibility optimization: PEG molecular brush modification (0.8 chains / nm² grafting density) reduces protein non-specific adsorption by 92% while maintaining antibody activity loss of <5%, ensuring the sensitivity and specificity of immunoassay.

[0101] Feasibility of large-scale production: The template imprinting method for preparing micro-nano composite structures, combined with in-situ LIPC formation technology, reduces the production cost of a single test card by 60%, and the contact angle variation between batches is <3°, meeting the economic requirements of disposable equipment.

[0102] Enhanced environmental adaptability: The combined design of temperature-sensitive phase change lubricant and pH-responsive pore structure enables the system to maintain flow rate stability (ΔCV<2%) within the temperature fluctuation range of 4-40℃ and pH range of 5-9, adapting to the physiological variation characteristics of pet urine.

[0103] Functional expansion potential: The modular design supports flexible configuration of detection indicators, and the combination of magnetic interface (leakage rate <0.5 μL / min) and replaceable detection modules provides a technical basis for personalized diagnostic needs.

[0104] This technology provides a multi-indicator urine testing solution for the pet health monitoring field that combines high synchronicity, low cost, and ease of use. Its core design principle can be further extended to parallel testing scenarios for other biological fluids.

[0105] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multi-channel synchronous detection card for pet urine, characterized in that, include: Sample loading area, used to receive pet urine samples; A microfluidic detection channel array, comprising multiple microfluidic detection channels arranged in parallel and isolated from each other; A biomimetic micro / nano hierarchical structure is disposed on at least a portion of the inner surface of each of the microfluidic detection channels; A liquid-injected porous coating is applied to the surface of the biomimetic micro / nano hierarchical structure. The detection area is connected to each of the microfluidic detection channels and is used to generate detection signals; The biomimetic micro / nano hierarchical structure is used to guide urine to spread in a predetermined direction at the geometric level, and the liquid-injected porous coating is used to reduce the contact angle hysteresis of urine on the inner surface of the channel and weaken the interfacial adhesion resistance. The two work together to enable urine samples to flow synchronously in multiple microfluidic detection channels under capillary force without external driving conditions, thereby achieving synchronous detection of multiple indicators.

2. The detection card according to claim 1, characterized in that, The biomimetic micro / nano hierarchical structure includes: A microscale groove structure extending axially along the microfluidic detection channel; Nanoscale protrusions are disposed on the surface of the microscale trench structure or in the region between the trenches. To form a hierarchical surface structure with direction selectivity.

3. The detection card according to claim 2, characterized in that, The microscale groove structure simulates the anisotropic wetting structure of natural biological surfaces, making the spreading resistance of urine in the axial direction of the groove less than the spreading resistance in the lateral direction.

4. The detection card according to claim 1, characterized in that, The liquid-injected porous coating includes: A porous polymer matrix formed on the surface of the biomimetic micro / nano hierarchical structure; A lubricating liquid is injected and stably maintained in the pores of the porous polymer matrix; The lubricating fluid and the porous polymer matrix form a continuous lubrication interface under operating conditions.

5. The detection card according to claim 4, characterized in that, When the liquid-injected porous coating is disturbed by repeated contact with urine or localized wetting of the surface, it can maintain the stability of the surface wetting performance within the channel by redistributing the lubricating liquid in the porous matrix.

6. The detection card according to claim 1, characterized in that, The inlet region of the microfluidic detection channel array is provided with a flow-dividing structure, which is used to evenly distribute the flow rate before urine enters multiple microfluidic detection channels, so as to reduce the flow rate difference between different detection channels.

7. The pet urine multi-channel synchronous detection card and method according to claim 1, characterized in that, The detection area includes a lateral chromatography detection component, which includes a detection line and a control line for colorimetric detection of target analytes in urine.

8. The method for simultaneous multi-indicator detection of pet urine using the detection card according to any one of claims 1-7, characterized in that, include Load the urine sample into the sample loading area; Through the synergistic effect of biomimetic micro / nano hierarchical structures and liquid-injected porous coatings, urine is synchronously flowed in multiple microfluidic detection channels under capillary force. Multiple detection signals corresponding to different detection indicators are generated in the detection area and interpreted synchronously.

9. The method according to claim 8, characterized in that: The time difference between urine flow completion in multiple microfluidic detection channels is less than a preset threshold, ensuring that the detection results of each indicator are comparable.

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