Manufacturing method of hydrophobic structure sampling needle based on lost foam

Abstract

The manufacturing method comprises the following steps: preparing the evanescent mode capable of being gasified at high temperature according to the shape of a target inner cavity of the sample adding needle, installing the evanescent mode in a deposition device, applying a direct-current electric field between an auxiliary electrode and a conductive electrode through an electric field deposition power supply, and directionally depositing a nano material under the action of the electric field, obtaining a functional layer and a sampling needle body; according to the deposited structure, the lost foam is gasified through high-temperature melting, and the sample adding needle body is synchronously solidified; and carrying out structure enhancement and performance stabilization treatment on the surface of the solidified sampling needle body to obtain the sampling needle with the super-hydrophobic micro-nano structure on the inner surface. According to the scheme, the process controllability is high, the method is suitable for multi-specification product design, large-scale production is easy, and manufacturing consistency is high.

Description

Technical Field

[0001] This invention belongs to the field of medical devices, and in particular relates to a method for manufacturing a hydrophobic structure sampling needle based on lost foam casting. Background Technology

[0002] With the rapid development of global medical technology, in vitro diagnostic (IVD) devices, as important tools for precision medicine and early disease screening, are widely used in various scenarios such as hospital clinical testing, biopharmaceuticals, disease screening, and scientific research experiments. Among these, the pipetting system in IVD devices undertakes critical operations such as sample aspiration, transfer, dispensing, and mixing, and its performance directly affects the accuracy and repeatability of test results. Therefore, the performance and manufacturing quality of the pipetting needle, as the core component of the pipetting system, are fundamental to ensuring the stable and reliable operation of the in vitro diagnostic device.

[0003] As a crucial channel for the transfer of micro-volume liquids, the sample dispensing needle is typically a hollow syringe or conical tube structure, with dimensions mostly below the millimeter level and inner diameters as small as tens of micrometers. It requires excellent airtightness, dimensional consistency, chemical inertness, and biocompatibility. In practical use, the sample dispensing needle frequently comes into contact with various highly sensitive liquids such as blood, serum, nucleic acid solutions, and biochemical reagents. If any liquid residue remains, it can easily cause cross-contamination between samples, affecting the accuracy of the test data and even leading to misdiagnosis. Therefore, its technical parameters, such as the smoothness of the inner hole, the manufacturing precision of the variable-diameter inner hole, and the smoothness of the outer surface, determine the manufacturing quality of the sample dispensing needle.

[0004] Currently, to reduce the residue problem of sample dispensing needles or similar microfluidic devices during liquid transfer, research institutions at home and abroad are attempting to construct hydrophobic or superhydrophobic layers on the inner wall of the sample dispensing needle to reduce liquid adhesion and improve anti-contamination capabilities. The main methods include physical etching and surface coating. Physical etching methods typically employ laser etching, reactive ion etching (RIE), and plasma micro-etching to form micron- or nanometer-scale uneven structures on the inner wall, simulating the "lotus effect" to achieve hydrophobic properties. However, this method faces several technical challenges in practical applications. For example, lasers struggle to form continuous, regular patterns inside the needle; etching equipment is expensive and energy-intensive; and the narrow inner cavity of the sample dispensing needle easily creates processing dead zones, leading to uneven microstructure construction. Furthermore, the constructed nanostructures lack stability in real-world medical environments such as high temperature and humidity, and are prone to structural collapse or functional degradation.

[0005] Another common approach is to coat the inner wall surface with a hydrophobic layer using fluorinated polymers (such as PTFE and PVDF) or silane modifiers (such as OTS and FAS) to reduce surface energy and achieve a liquid-repellent effect. While this method is relatively simple, the coating is extremely thin and easily damaged by high temperatures, acids, alkalis, or strong oxidizing environments. Furthermore, its adhesion is weak, making it prone to detachment during prolonged liquid rinsing or ultrasonic cleaning, leading to functional failure. In addition, some fluorinated chemical reagents pose certain biological toxicity and environmental risks, hindering safe application and industrialization. Most importantly, whether through physical etching or coating, the functional layer is separated from the needle structure, resulting in poor reliability and a short lifespan.

[0006] For the sample dispensing needle body, the existing sample dispensing needle manufacturing methods are mainly based on traditional molding methods such as injection molding, stretching, and welding. They lack the ability to accurately construct micro-nano functional structures in tiny inner wall spaces. Although constructing superhydrophobic structures through post-processing can improve performance to some extent, it has problems such as narrow processing window, complex process, and high cost, making it difficult to meet the current IVD system's integrated requirements for high precision, high cleanliness, and large-scale manufacturing.

[0007] Therefore, developing a novel manufacturing method capable of constructing stable and highly functional superhydrophobic micro / nano structures in situ on the inner wall of a sample feeding needle and integrating them with the main body structure is a key direction that urgently needs breakthrough in the field. Meanwhile, traditional sample feeding needle manufacturing methods mainly rely on injection molding, stretching, welding, and bonding, which cannot accurately construct micro / nano-scale functional structures within the confined inner wall space. While post-processing the inner wall using methods such as laser etching and ion beam etching can achieve a certain degree of functional surface structure construction, its narrow processing window, expensive equipment, and low efficiency severely restrict large-scale applications and process integration. Summary of the Invention

[0008] To solve the above-mentioned technical problems, the present invention provides a method for manufacturing a hydrophobic structured sample needle based on lost foam casting, comprising:

[0009] A high-temperature vaporization lost mold is prepared according to the target inner cavity shape of the sample dispensing needle. The lost mold is installed in a deposition device. A DC electric field is applied between the auxiliary electrode and the conductive electrode through an electric field deposition power supply. Nanomaterials are directionally deposited under the action of the electric field to obtain a functional layer and a sample dispensing needle body.

[0010] Based on the structure after deposition, the lost foam is vaporized by high-temperature melting and the sample injection needle body is solidified simultaneously.

[0011] The surface of the cured sample needle body is subjected to structural reinforcement and performance stabilization treatment to obtain a sample needle with a superhydrophobic micro-nano structure on the inner surface.

[0012] Preferably, the process of preparing a high-temperature vaporizable lost foam according to the target cavity shape of the sampling needle includes:

[0013] Based on the required internal geometry parameters of the injection needle, a lost foam mold with the shape of the injection needle cavity is used to form polystyrene or polylactic acid lost foam through 3D printing or precision injection molding.

[0014] Preferably, the lost foam mold with the shape of a sample dispensing needle cavity is provided with a conductive electrode structure inside;

[0015] The outer wall surface of the lost foam includes pre-constructed periodic micro / nano structures;

[0016] The conductive electrode structure is connected to the micro / nano structure.

[0017] Preferably, the micro / nano structure includes a columnar array, a trench structure, or a conical micropore;

[0018] The micro-nano array has a height of 0.5–10 μm, a width of 100–1000 nm, and a spacing of 0.5–5 μm.

[0019] Preferably, the process of directionally depositing nanomaterials under the action of an electric field to obtain a functional layer and a sample dispensing needle body includes:

[0020] The lost foam was placed in a suspension containing nanomaterials;

[0021] A DC electric field of 10–40V is applied between the conductive electrode and the auxiliary electrode;

[0022] Under the influence of an electric field, nanomaterials are directionally migrated from the working liquid tank to the inner wall surface of the lost foam casting, and deposited under the guidance of the existing micro-nano structure to gradually construct a periodic micro-nano structure functional layer and a connected sample needle body.

[0023] Preferably, the suspension is a 0.5–2.0 wt% dispersion system of metal nanoparticles in a solvent, the deposition temperature is 25–45℃, the deposition time is 15–60 min, and the stirring speed is 300–600 rpm.

[0024] Preferably, based on the completed deposition structure, the process of vaporizing the lost foam through high-temperature melting and simultaneously solidifying the sample dispensing needle body includes:

[0025] The deposited lost foam is placed in a high-temperature melting chamber;

[0026] Heat to the set temperature at a rate of 5℃ / min, hold for 30–90 min, in a nitrogen or vacuum atmosphere;

[0027] The lost foam vaporizes and escapes, the deposited layer sintersulates and is transferred one-to-one with the template space to form a dense needle-like structure.

[0028] Preferably, the temperature of the high-temperature cavity is set to a temperature range that is higher than the vaporization temperature of the lost foam material and lower than the melting point of the nanomaterial.

[0029] Preferably, the process of structurally strengthening and stabilizing the surface of the cured sample dispensing needle includes:

[0030] The cured sample dispensing needle body is subjected to low-temperature annealing at 120–180℃ for 2 hours;

[0031] Based on the structure after annealing, PDMS vapor encapsulation or fluorosilane modification treatment is performed;

[0032] Based on the encapsulated or modified structure, low-energy plasma is used to reconstruct the nanoparticle interface.

[0033] Preferably, the solidified sample needle body is made of metal or alloy material, and the microstructure of the inner surface is at least one of columnar array, groove structure or conical micropore.

[0034] Compared with the prior art, the present invention has the following advantages and technical effects:

[0035] This invention integrates a functional superhydrophobic micro / nano structure with the sample needle body through a process of "lost foam guidance + electric field deposition + melt molding". This improves the structural stability and long-term reliability from the source, significantly reduces the risk of coating peeling and functional degradation, and achieves a dual improvement in performance and reliability.

[0036] This invention takes into account the synergistic effect of the micro-nano structure of the inner wall surface and the low surface energy nanomaterials to construct a biomimetic functional microstructure, which enables the sample dispensing needle to have superhydrophobic properties with a contact angle greater than 150° and a roll-off angle less than 10°, with residual liquid volume as low as 0.05μL or less. It can effectively prevent liquid adhesion and cross-contamination, greatly improve the liquid dispensing accuracy, meet the high throughput and high cleanliness operation requirements of IVD equipment, and has excellent superhydrophobic properties while significantly reducing residual liquid.

[0037] This invention uses non-toxic and pollution-free materials and low-energy-consumption processes, eliminating the need for harmful chemical reagents. The preparation process is green, safe, and sustainable, meeting the stringent requirements of the medical device industry for biocompatibility and environmental protection.

[0038] The solution described in this invention has strong process controllability and is adaptable to the design of products with multiple specifications. Specifically, the particle type, concentration, voltage, and electric field time in the electric field deposition process can all be adjusted, and the density and morphology of the micro-nano structure can be designed as needed. The lost foam template can be flexibly replaced, enabling the rapid development and manufacturing of sample needles with different diameters, lengths, and structures. It has good process scalability and product versatility.

[0039] This invention is easy to scale up and produces with high manufacturing consistency. Compared with post-processing methods such as laser etching and spraying, this invention achieves a "three-in-one" integration of structure replication, functional construction, and body forming through template structure guidance and field-controlled deposition. It can be prepared in high-throughput mode using modular production lines, with stable processes and good batch consistency, making it suitable for industrial mass production.

[0040] The method of this invention has a wide range of applications and is of general promotion value. This process is not only applicable to the manufacture of sampling needles, but can also be extended to other hollow structural components that require hydrophobic internal surfaces, such as sampling tubes, spotting needles, microreactor channels, and microfluidic chips, demonstrating good cross-product adaptability and industrialization potential. Attached Figure Description

[0041] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0042] Figure 1 This is a schematic diagram of the lost foam casting structure and the outer wall micro / nano structure according to an embodiment of the present invention;

[0043] Figure 2 This is a schematic diagram of the electric field-assisted deposition system according to an embodiment of the present invention;

[0044] Figure 3 This is a schematic diagram of the molten cavity and integrally formed structure according to an embodiment of the present invention;

[0045] Among them, 1. Lost foam; 11. Micro-nano structure; 2. Conductive electrode; 3. Electric field deposition power source; 4. Auxiliary electrode; 5. Suspension; 6. Working fluid tank; 7. Sample needle body and internal surface functional microstructure; 8. Sample needle body; 9. Internal wall surface functional microstructure. Detailed Implementation

[0046] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0047] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0048] like Figures 1-3As shown, this embodiment provides an integrated additive manufacturing method for sample dispensing needles. It employs a four-stage collaborative process of lost foam molding, electric field deposition, melt forming, and structural solidification to solve problems in existing technologies such as the separation of the functional layer from the body structure and the difficulty in constructing micro / nano structures on the inner wall. This results in the construction of a high-performance structural needle with superhydrophobic properties. This method features a clear structure, stable process, and is suitable for mass production. This embodiment provides a method for manufacturing hydrophobic structural sample dispensing needles based on lost foam molding, including:

[0049] According to the target inner cavity shape of the sample needle, a high-temperature vaporizable lost foam 1 is prepared. The lost foam 1 is installed in the deposition device. A DC electric field is applied between the auxiliary electrode 4 and the conductive electrode 2 through the electric field deposition power supply 3. Nanomaterials are directionally deposited under the action of the electric field to obtain the functional layer and the sample needle body 8.

[0050] Based on the structure after deposition, the lost foam 1 is vaporized by high-temperature melting and the sample injection needle body 8 is solidified simultaneously;

[0051] The surface of the cured sample needle body 8 was subjected to structural reinforcement and performance stabilization treatment to obtain a sample needle with a superhydrophobic micro-nano structure on the inner surface.

[0052] Furthermore, the process of preparing the high-temperature vaporizable lost foam 1 according to the target inner cavity shape of the sampling needle includes:

[0053] Based on the required internal geometry parameters of the injection needle, a lost foam mold with the shape of the injection needle cavity is used to form polystyrene or polylactic acid lost foam through 3D printing or precision injection molding.

[0054] Furthermore, such as Figure 1 As shown, this embodiment employs a lost foam casting precision mold with a sample dispensing needle cavity shape. Polymer materials such as polystyrene (EPS) and polylactic acid (PLA), which can vaporize or decompose at high temperatures, are selected. The lost foam casting mold is fabricated using processes such as 3D printing and precision injection molding. A conductive electrode 2 is disposed inside the mold, and its outer surface is pre-constructed with periodic micro / nano structures 11, such as columnar arrays, groove structures, or conical micropores, forming the physical basis for the subsequent superhydrophobic structure. The micro / nano structures 11 are connected to the conductive electrode 2.

[0055] The size design range of the micro / nano structure 11 is as follows:

[0056] Height H: 0.5–10 μm;

[0057] Width W: 100–1000nm;

[0058] Spacing P: 0.5–5 μm.

[0059] Furthermore, the lost foam mold with the shape of a sample dispensing needle cavity is provided with a conductive electrode structure inside;

[0060] The outer surface of the lost foam 1 includes pre-constructed periodic micro / nano structures;

[0061] Furthermore, the micro / nano structure 11 includes columnar arrays, trench structures, conical micropores, etc.

[0062] The micro-nano array has a height of 0.5–10 μm, a width of 100–1000 nm, and a spacing of 0.5–5 μm.

[0063] Furthermore, the process of directionally depositing nanomaterials under an electric field to obtain the functional layer and the sample dispensing needle body 8 includes:

[0064] The lost foam 1 was placed in a suspension 5 containing nanomaterials;

[0065] A DC electric field of 10–40V is applied between the conductive electrode 2 and the auxiliary electrode 4;

[0066] Under the influence of the electric field, the nanomaterials are directionally migrated from the working liquid tank 6 to the inner wall surface of the lost foam, and deposited under the guidance of the existing micro-nano structure to gradually construct a periodic micro-nano structure functional layer and the connected sample needle body 8.

[0067] Furthermore, the electric field-assisted nanomaterial deposition process in this embodiment specifically includes:

[0068] Install the lost foam 1 as follows: Figure 2 In the deposition apparatus shown, a DC electric field is applied between the auxiliary electrode 4 and the conductive electrode 2 through the electric field deposition power supply 3, so that functional nanomaterials (such as metal powder for constructing the needle body) are directionally migrated from the working liquid tank 6 to the inner wall surface of the lost foam 1, and deposited under the guidance of the existing micro-nano structure 11, gradually constructing a periodic micro-nano structure functional layer and the connected sample needle body 8.

[0069] By controlling the parameters of the electric field deposition power source 3, needle structures of different thicknesses can be deposited and formed. The uniformity of needle thickness at different locations is controlled by utilizing the electric field effect between the electrodes.

[0070] The deposition parameters are as follows: voltage: 10–40V; suspension concentration: 0.5–2.0wt%; deposition time: 15–60min; temperature: 25–45℃; stirring speed: 300–600rpm.

[0071] Furthermore, the suspension is a 0.5–2.0 wt% dispersion system of metal nanoparticles in a solvent, the deposition temperature is 25–45℃, the deposition time is 15–60 min, and the stirring speed is 300–600 rpm.

[0072] Furthermore, based on the completed deposition structure, the process of vaporizing the lost foam 1 and simultaneously solidifying the sample dispensing needle body 8 through high-temperature melting includes:

[0073] The deposited lost foam 1 is placed in a high-temperature melting cavity;

[0074] Heat to the set temperature at a rate of 5℃ / min, hold for 30–90 min, in a nitrogen or vacuum atmosphere;

[0075] The lost foam 1 vaporizes and escapes, the deposited layer is sintered and transferred one-to-one with the template space to form a dense needle-like structure.

[0076] Furthermore, such as Figure 3 As shown, in this embodiment, after deposition, the lost foam 1 is placed entirely into a high-temperature melting cavity for molding. The temperature is slowly increased to a set temperature, the mold body vaporizes and escapes, leaving the deposited layer as the molded needle structure. During the process, the deposited layer undergoes sintering or fusion, transferring itself one-to-one with the space occupied by the template, ultimately forming the sample dispensing needle body 8 and the functional microstructure 9 on the inner wall surface. The sample dispensing needle structure obtained after molding is dense and has an intact inner wall structure, avoiding deformation and micro-leakage problems caused by traditional bonding and welding processes.

[0077] The control parameters are as follows:

[0078] Heating rate: 5℃ / min;

[0079] Insulation time: 30–90 min;

[0080] Thermal atmosphere: nitrogen or vacuum environment to prevent oxidation;

[0081] Demolding method: gravity release or gas-assisted extraction.

[0082] Furthermore, the temperature of the high-temperature chamber is set to a temperature range that is higher than the vaporization temperature of the lost foam material and lower than the melting point of the nanomaterial.

[0083] Furthermore, the process of structural reinforcement and performance stabilization treatment on the surface of the cured sample dispensing needle body 8 includes:

[0084] The cured sample dispensing needle body is subjected to low-temperature annealing at 120–180℃ for 2 hours;

[0085] Based on the structure after annealing, PDMS vapor encapsulation or fluorosilane modification treatment is performed;

[0086] Based on the encapsulated or modified structure, low-energy plasma is used to reconstruct the nanoparticle interface.

[0087] Furthermore, to improve the corrosion resistance, hydrophobic properties, and surface stability of the final structure, the following processing steps can be optionally included in this embodiment:

[0088] Low-temperature heat treatment (e.g., annealing at 120–180℃ for 2 hours) releases micro-stress;

[0089] Surface energy modulation treatments: such as PDMS vapor encapsulation and fluorosilane modification;

[0090] Structural densification treatment: Low-energy plasma is used to reconstruct the contact interface of nanoparticles, thereby improving adhesion and functional stability.

[0091] After the above processing, the obtained sample needle structure exhibits the following indicators:

[0092]

[0093]

[0094] Furthermore, the solidified sample needle body 8 is made of metal or alloy material, and the microstructure of its inner surface is at least one of columnar array, groove structure or conical micropore.

[0095] Based on the principle of precision mold forming, this embodiment proposes a novel additive manufacturing scheme that integrates nanomaterial deposition with bulk forming process using lost foam technology. This scheme can form a high-quality superhydrophobic micro-nano structure on the inner wall of the template and solidify it as a whole to form the sample needle body 8 through a high-temperature melting process. This achieves the synergistic integration of needle structure and functional layer, providing a new idea and process path for solving the problems of liquid residue, manufacturing consistency and structural-functional integration of sample needles.

[0096] The technical method of this embodiment has outstanding comprehensive advantages in terms of precision, cleanliness, safety, scalability and manufacturing cost control, and is expected to achieve application breakthroughs in multiple high-end medical equipment fields such as in vitro diagnostics, precision biological pipetting, and drug screening.

[0097] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for manufacturing a hydrophobic structure sample needle based on a lost mold, characterized by, The method comprises the following steps: According to the shape of the target inner cavity of the sample loading needle, a lost mold capable of high-temperature gasification is prepared, the lost mold is installed in a deposition device, a functional layer and a sample loading needle body are obtained by depositing a nano material under the action of an electric field, a direct current electric field is applied between an auxiliary electrode and a conductive electrode, and the nano material is deposited in a directional manner under the action of the electric field. According to the structure after deposition is completed, the lost mold is gasified by high-temperature melting and the sample loading needle body is solidified synchronously. The surface of the solidified sample loading needle body is subjected to structure enhancement and performance stabilization treatment, and the sample loading needle with an inner surface having a super-hydrophobic micro-nano structure is obtained.

2. The method of claim 1, wherein The process of preparing the lost mold capable of high-temperature gasification according to the shape of the target inner cavity of the sample loading needle comprises: According to the inner cavity geometric parameters of the required sample loading needle, a lost mold mold with the shape of the sample loading needle cavity is used, and a polystyrene or polylactic acid lost mold is formed by 3D printing or precision injection molding.

3. The method of claim 2, wherein The lost mold mold with the shape of the sample loading needle cavity is internally provided with a conductive electrode structure; The outer wall surface of the lost mold comprises a pre-constructed periodic micro-nano structure; The conductive electrode structure is communicated with the micro-nano structure.

4. The method of claim 3, wherein The micro-nano structure comprises a columnar array, a groove structure, and a conical micropore; The height of the micro-nano array is 0.5-10 μm, the width is 100-1000 nm, and the pitch is 0.5-5 μm.

5. The method of claim 1, wherein The process of depositing a nano material in a directional manner under the action of an electric field to obtain a functional layer and a sample loading needle body comprises: The lost mold is placed in a suspension containing a nano material; A 10-40 V direct current electric field is applied between the conductive electrode and the auxiliary electrode; According to the action of the electric field, the nano material is migrated from the working liquid tank to the inner wall surface of the lost mold in a directional manner, and is accumulated under the guidance of the existing micro-nano structure, thereby gradually constructing a periodic micro-nano structure functional layer and a connected sample loading needle body.

6. The method of claim 5, wherein The suspension is a 0.5-2.0 wt% dispersion system of metal nano powder in a solvent, the deposition temperature is 25-45°C, the deposition time is 15-60 min, and the stirring speed is 300-600 rpm.

7. The method of claim 1, wherein The process of gasifying the lost mold by high-temperature melting and synchronously solidifying the sample loading needle body according to the structure after deposition is completed comprises: The deposited lost mold is placed in a high-temperature melting cavity; The temperature is raised to a set temperature at a rate of 5°C / min, and the temperature is kept for 30-90 min in an atmosphere of nitrogen or vacuum; The lost mold is gasified and escapes, the deposited layer is sintered and is one-to-one transcribed with the mold space, thereby forming a dense needle body.

8. The method of claim 7, wherein The temperature of the high-temperature cavity is set to a temperature interval higher than the gasification temperature of the lost mold material and lower than the melting point of the nano material.

9. The method of claim 1, wherein The process of subjecting the surface of the solidified sample loading needle body to structure enhancement and performance stabilization treatment comprises: After solidification, the sample needle body is annealed at 120-180℃ for 2h; According to the structure after annealing, PDMS vapor sealing or fluorosilane modification treatment is carried out; According to the structure after sealing or modification, low-energy plasma is used to reconfigure the nanoparticle interface.

10. The method of claim 1, wherein, The solidified sample needle body is a metal or alloy material, and the inner surface microstructure is at least one of a columnar array, a groove structure, or a conical micropore.

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