Surface processing method for medical metal instruments with anti-adhesion property

Abstract

This invention discloses a method for surface processing of medical metal instruments with anti-adhesion properties, comprising the following steps: S1, pretreating the substrate surface of the medical metal instrument; S2, using a femtosecond laser to scan and etch the pretreated substrate surface to construct a biomimetic microtexture with micron-level structural features and nanometer-level roughness; S3, immersing the surface treated in step S2 in a stearic acid-ethanol solution for chemical modification to form a hydrophobic molecular layer on the surface of the biomimetic microtexture, thereby obtaining a superhydrophobic anti-adhesion surface. This invention can stably construct biomimetic micro / nanostructures with excellent superhydrophobic properties on the surface of medical metal instruments, thereby significantly reducing the adhesion of biological media such as blood and tissue, improving surgical efficiency and instrument lifespan.

Description

Technical Field

[0001] This invention relates to the field of medical device surface treatment technology, and in particular to a method for surface processing of medical metal devices with anti-adhesion properties. Background Technology

[0002] In the medical field, surgical instruments (such as electrosurgical units, scalpels, scissors, forceps, etc.) easily accumulate blood, tissue, and other biological media on their surfaces during use. Taking electrosurgical scalpels as an example, their high operating temperatures cause these deposits to dehydrate and form eschar, leading to decreased electrical and thermal conductivity, affecting surgical efficiency and safety, and potentially even causing tissue tearing. For reusable instruments, these deposits increase the difficulty of cleaning and sterilization, potentially causing corrosion, decreased precision, or cross-infection risks.

[0003] To reduce adhesion, traditional methods rely on intraoperative wiping or rinsing, which cannot solve the problem in real time and thoroughly. In recent years, inspired by superhydrophobic phenomena in nature such as lotus leaves (the "lotus effect"), researchers have attempted to construct superhydrophobic structures on instrument surfaces. Superhydrophobic surfaces can effectively reduce the contact and adhesion of liquids, cells, and tissues. Currently, laser etching technology shows advantages in the preparation of superhydrophobic metal surfaces due to its high processing precision, wide material adaptability, and strong controllability. However, in existing technologies, how to construct efficient and durable superhydrophobic anti-adhesion surfaces on commonly used medical metals (such as 316L stainless steel and TC4 titanium alloy) through a stable and repeatable process, especially by optimizing the processing parameters of ultrafast lasers (such as femtosecond lasers) and the synergistic effect of surface chemical modification, for the specific working conditions of medical metal instruments (such as biocompatibility, wear resistance, and non-toxicity), remains an urgent problem to be solved. Summary of the Invention

[0004] The purpose of this invention is to provide a method for processing the surface of medical metal instruments with anti-adhesion properties. This invention can stably construct biomimetic micro / nano structures with excellent superhydrophobic properties on the surface of medical metal instruments, thereby significantly reducing the adhesion of biological media such as blood and tissue, and improving surgical efficiency and instrument lifespan.

[0005] The technical solution of this invention: A method for surface processing of medical metal instruments with anti-adhesion properties, comprising the following steps: S1. Pre-treat the substrate surface of medical metal instruments; S2. A femtosecond laser is used to scan and etch the pretreated substrate surface to construct a biomimetic microtexture with micron-level structural features and nanon-level roughness on the substrate surface. S3. The surface treated in step S2 is immersed in a stearic acid ethanol solution for chemical modification to form a hydrophobic molecular layer on the biomimetic microtexture surface, thereby obtaining a superhydrophobic and anti-adhesion surface.

[0006] In the above-mentioned method for surface processing of medical metal devices with anti-adhesion properties, in step S2, the biomimetic microtexture is selected from at least one of papillary structure or mesh structure; the micron-level structural features include: the base diameter of the papilla in the papillary structure is 5-9 μm and the height is 4-8 μm, or the width of the groove in the mesh structure is 40-60 μm, the depth is 6-10 μm, and the mesh spacing is 40-60 μm.

[0007] In the aforementioned method for surface processing of medical metal devices with anti-adhesion properties, the wavelength of the femtosecond laser in step S2 is 1064nm.

[0008] In the aforementioned method for processing the surface of medical metal devices with anti-adhesion properties, in step S2, the processing parameters of the femtosecond laser meet the following requirements: laser power of 9-12W, scanning speed of 300-600mm / s, number of scans of 3-5, and scanning interval of 25-75μm.

[0009] In the aforementioned method for processing the surface of medical metal devices with anti-adhesion properties, the processing parameters of the femtosecond laser in step S2 are: laser power 12W, scanning speed 500mm / s, number of scans 4, and scanning interval 50μm.

[0010] In the aforementioned method for surface processing of medical metal devices with anti-adhesion properties, in step S3, the concentration of the stearic acid ethanol solution is from 0.05 mol / L to 0.2 mol / L.

[0011] In the aforementioned method for surface processing of medical metal devices with anti-adhesion properties, the concentration of the stearic acid ethanol solution in step S3 is 0.1 mol / L.

[0012] In the aforementioned method for surface processing of medical metal devices with anti-adhesion properties, step S3 involves immersion treatment for 20 to 40 minutes; after immersion treatment, a heat treatment curing step is also included, wherein the heat treatment curing temperature is 100 to 140°C and the time is 0.5 to 2 hours.

[0013] The aforementioned method for processing the surface of medical metal devices with anti-adhesion properties includes, in step S1, the pretreatment process comprising: sequentially grinding, ethanol cleaning, ultrasonic cleaning, and drying the substrate surface.

[0014] The aforementioned surface processing method for medical metal devices with anti-adhesion properties, wherein the base material of the medical metal device is selected from 316L stainless steel, 420 stainless steel or TC4 titanium alloy.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention constructs a micro-nano hierarchical rough structure on a metal surface using a femtosecond laser, and combines it with a stearic acid molecular layer to reduce surface energy, thus achieving a superhydrophobic surface with a contact angle greater than 150° and a roll-off angle less than 20°. This effectively prevents the adhesion of blood, tissue, etc., and simplifies the intraoperative cleaning process.

[0016] 2. By optimizing the synergistic effect of core parameters such as femtosecond laser power, scanning speed, scanning spacing, and number of scans, this invention clarifies the influence of each parameter on surface morphology and wettability, determines the optimal process window, and ensures the stability and repeatability of the processing results.

[0017] 3. The method of the present invention is applicable to commonly used medical metal materials such as 316L stainless steel, 420 stainless steel, and TC4 titanium alloy, and has good universality.

[0018] 4. The surface modification layer of the present invention has a molecular-level thickness, which does not affect the core properties of the base material such as mechanical strength and corrosion resistance, and meets the requirements for use in medical devices.

[0019] 5. Surgical instruments treated using the method of this invention can reduce surgical time, lower the risk of infection, and extend instrument life, and have the potential to improve medical safety and reduce medical costs. Attached Figure Description

[0020] Figure 1 This is a flowchart illustrating the method of the present invention; Figure 2 3D morphology images of 316L stainless steel surface under different molar concentrations in Group A are shown. Figure 3 The surface quality parameters of 316L stainless steel under different molar concentrations in Group A are shown, where (a) is the surface roughness and (b) is the contact angle. Figure 4 3D morphology images of 316L stainless steel surface under different molar concentrations in Group B are shown. Figure 5 The surface quality parameters of 316L stainless steel under different molar concentrations in Group B are shown, where (a) is the surface roughness and (b) is the contact angle. Figure 6 These are 3D morphology images of the surface of 316L stainless steel under different scan numbers in Group A; Figure 7 The figures show the surface quality parameters of 316L stainless steel under different scan numbers in Group A, where (a) shows the surface roughness and (b) shows the contact angle and machining depth. Figure 8 These are 3D morphology images of the surface of 316L stainless steel under different scan numbers in Group B. Figure 9The figures show the surface quality parameters of 316L stainless steel under different scan numbers in Group B, where (a) shows the surface roughness and (b) shows the contact angle and machining depth. Figure 10 The 3D morphology images of the 316L stainless steel surface under different scanning speeds are shown in Group A. Figure 11 The surface quality parameters of 316L stainless steel in Group A are shown at different scanning speeds, where (a) shows the surface roughness and (b) shows the contact angle and machining depth. Figure 12 The 3D morphology images of the 316L stainless steel surface in Group B at different scanning speeds are shown. Figure 13 The surface quality parameters of 316L stainless steel in Group B at different scanning speeds are shown, where (a) is the surface roughness and (b) is the contact angle and machining depth. Figure 14 The surface quality parameters of 316L stainless steel at different scanning intervals with a laser power of 3W are shown, where (a) is the surface roughness and (b) is the contact angle and machining depth. Figure 15 The surface quality parameters of 316L stainless steel at different scanning intervals with a laser power of 6W are shown, where (a) is the surface roughness and (b) is the contact angle and machining depth. Figure 16 The surface quality parameters of 316L stainless steel at different scanning intervals with a laser power of 9W are shown, where (a) is the surface roughness and (b) is the contact angle and machining depth. Figure 17 The surface quality parameters of 316L stainless steel at different scanning intervals with a laser power of 12W are shown, where (a) is the surface roughness and (b) is the contact angle and machining depth. Figure 18 This is a schematic diagram for measuring the static contact angle. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0022] Example 1: A surface processing method for medical metal devices with anti-adhesion properties, the specific steps of which are as follows: S1. Pretreatment: Take a 316L stainless steel surgical blade substrate. First, gently polish the surface to be treated with 2000-grit sandpaper until the macroscopic scratches on the surface are basically gone. If commercially available 316L stainless steel surgical blades are available, the polishing step can be omitted. Then, repeatedly wipe the surface with a lint-free cloth dampened with anhydrous ethanol to remove oil and polishing residue. Next, place the blade in an ultrasonic cleaner, add sufficient deionized water, and clean at a frequency of 40kHz for 10 minutes. Finally, dry the surface with clean nitrogen gas and place it in a desiccator for later use.

[0023] S2. Femtosecond laser construction of biomimetic microtextures: A femtosecond laser processing system with a wavelength of 1064nm is used. For example... Figure 1 As shown, this femtosecond laser processing optical path system uses a femtosecond laser as the light source. The output ultrashort pulse laser is sequentially shaped by a slit, and its polarization and energy are adjusted by a half-wave plate and a polarizer. The propagation direction is then changed by a mirror, and the laser is guided to the objective lens by a dichroic mirror, finally focusing on the surface of a stainless steel sample to achieve micro / nano structure etching. Simultaneously, the system is equipped with a CCD camera working in conjunction with the dichroic mirror to acquire sample images in real time for positioning, observation, and quality inspection during the processing. The entire optical path achieves high-precision scanning and accurate processing control through an X / Y / Z three-dimensional coordinate system. The equipment used in this embodiment is a five-axis laser micro-hole processing device, mainly composed of a SCANcubeⅢ10 scanning galvanometer system, a 20 W femtosecond laser processor, a Heidenhain grating ruler closed-loop system, a Siemens 840DSL CNC system, and a five-axis motion system. The femtosecond laser has a wavelength of 1064 nm, a maximum power of 20 W, a repetition rate of 10-600 kHz, and a maximum laser scanning speed of 5000 mm / s for the scanning galvanometer.

[0024] When performing 3D laser processing using a femtosecond laser, the 3D model needs to be processed in layers. The outlines of each layer are then vertically projected onto a horizontal plane. The resulting 2D outline files are converted to DWG format and imported into the laser processing control system. In the control software, the processing area is filled with a path, and initial process parameters such as laser power, scanning speed, and repetition frequency are set. The processing reference coordinate system is determined by moving the work platform, and the focal plane position is located using laser focus detection. Finally, based on the preset processing parameters and path planning, a laser scanning trajectory is generated, and layered cumulative processing is performed, ultimately machining the set trajectory.

[0025] The pre-treated cutting tool was fixed on the worktable, and the laser processing parameters were set as follows: laser power 12W, scanning speed 500mm / s, scanning interval 50μm, and 4 scans. The laser beam was controlled to scan and etch a specific area on the cutting tool surface. After processing, observation by scanning electron microscopy (SEM) revealed a periodically arranged micron-sized papillary structure on the surface. The base diameter of a single papillary was approximately 8μm, the height was approximately 6μm, and the center-to-center distance between papillae was approximately 10μm. Uniformly distributed nanoscale protrusions with sizes between 200-500nm were visible on the surface and between the papillae, forming a micro-nano hierarchical rough structure. The surface roughness (Sa) of this region was measured to be 4.71μm by laser confocal microscopy.

[0026] S3. Low surface energy chemical modification: Prepare a 0.1 mol / L stearic acid-ethanol solution. Completely immerse the laser-processed blade in this solution and let it stand at room temperature for 30 minutes. After removal, hold it with tweezers and heat-treat it in a 120℃ forced-air drying oven for 1 hour. Then, remove the sample and allow it to cool at room temperature.

[0027] Example 2: A surface processing method for medical metal devices with anti-adhesion properties, the specific steps of which are as follows: S1. Pretreatment: Take a 316L stainless steel surgical forceps and pretreatment its occlusal surface. The steps are the same as step 1 in Example 1: perform fine polishing, ethanol wiping, ultrasonic cleaning (deionized water, 10 minutes), and nitrogen drying in sequence.

[0028] Femtosecond laser construction of biomimetic microtexture: A femtosecond laser with a wavelength of 1064 nm was used (same as in Example 1). The process parameters were set as follows: laser power 9W, scanning speed 500 mm / s, and 4 scans. The laser scanning path was controlled by programming to perform bidirectional line scans perpendicular to each other on the interlocking surface, with the line spacing (i.e., groove center distance) set to 50 μm. After processing, a regular grid-like microtexture was formed with a groove width of approximately 50 μm, a groove depth of approximately 8 μm, and a grid platform width of approximately 50 μm. Both the interior of the grooves and the surface of the platforms exhibited nanoscale roughness.

[0029] Low surface energy chemical modification: Prepare a 0.1 mol / L stearic acid-ethanol solution. Immerse the processed part of the surgical forceps in the solution for 30 minutes, then remove and cure at 120℃ for 1 hour, followed by cooling to room temperature.

[0030] Example 3: A surface processing method for medical metal devices with anti-adhesion properties, the specific steps of which are as follows: S1. Pretreatment: Take a TC4 titanium alloy flat plate specimen. The pretreatment steps are the same as step 1 in Example 1, ensuring the surface is clean.

[0031] S2. Femtosecond Laser Construction of Biomimetic Microtextures: The same femtosecond laser processing system and process parameters as in Example 1 were used: laser power 12W, scanning speed 500mm / s, scanning spacing 50μm, and 4 scans. Scanning etching was performed on the surface of TC4 titanium alloy to construct a micro / nano hierarchical rough structure.

[0032] S3. Low surface energy chemical modification: The same chemical modification conditions as in Example 1 were used: 0.1 mol / L stearic acid ethanol solution, soaked for 30 minutes, and cured at 120°C for 1 hour.

[0033] Example 4: This example investigated the effect of stearic acid modification concentration on surface properties. The specific steps are as follows: Two sets of representative femtosecond laser processing parameters were selected to prepare microstructured surfaces as modification substrates: Group A (laser power 6 W, scanning spacing 75 μm, scanning speed 500 mm / s, 4 scans) and Group B (laser power 12 W, scanning spacing 25 μm, scanning speed 500 mm / s, 4 scans). Based on these, stearic acid-ethanol solutions with molar concentrations of 0.01 mol / L, 0.02 mol / L, 0.05 mol / L, 0.1 mol / L, and 0.2 mol / L were prepared. The laser-treated samples were immersed in solutions of different concentrations for 30 minutes, then removed and heat-treated in an oven at 120℃ for 1 hour to promote the bonding of carboxyl groups to the matrix and enhance the stability and density of the modified layer.

[0034] Figure 2 3D morphology images of 316L stainless steel surface under different molar concentrations in Group A are shown. Figure 3 The surface quality parameters of 316L stainless steel under different molar concentrations in Group A are shown, where (a) is the surface roughness and (b) is the contact angle. Figure 4 3D morphology images of 316L stainless steel surface under different molar concentrations in Group B are shown. Figure 5 The surface quality parameters of 316L stainless steel under different molar concentrations in Group B are shown, where (a) is the surface roughness and (b) is the contact angle.

[0035] like Figure 2 and Figure 4As shown, under low-concentration stearic acid modification, the 3D morphology under laser confocal microscopy did not change significantly. This confirms that stearic acid modification forms a molecular-thick coating that does not significantly alter the micron-scale morphology of the laser-processed substrate. However, modification with a 0.2 mol / L stearic acid-ethanol solution drastically alters the surface microstructure. At lower concentrations, the number of stearic acid molecules in the solution is limited. When they come into contact with a laser-activated stainless steel surface (rich in polar groups such as -OH), their hydrophilic carboxyl groups (-COOH) preferentially and directionally adsorb onto high-energy active sites on the surface through chemical bonds (such as forming metal soaps) or strong hydrogen bonds. This adsorption is at the molecular level, forming a dense, ordered monolayer typically less than 2 nanometers thick. The thickness of this film is much smaller than the characteristic dimensions of the micron-scale or even hundred-nanometer-scale rough structures formed by laser processing. Therefore, instruments measuring macroscopic contours, such as laser confocal microscopy or white light interferometers, can hardly detect this nanometer-scale thickness change, thus appearing as "no change in morphology." When the solution concentration is too high, the concentration of stearic acid molecules in the solution far exceeds the monolayer adsorption capacity that the surface active sites can accommodate. After the formation of a monolayer through chemisorption, excess stearic acid molecules will undergo physical adsorption and accumulation on the existing monolayer through intermolecular van der Waals forces (hydrophobic chain interactions), forming a disordered, relatively thick multilayer. This physical accumulation is non-directional, thick, and potentially non-uniform. Its thickness can reach tens or even hundreds of nanometers, sufficient to begin "filling" or "passivating" the finest secondary nanoscale features (such as...) in the micro / nanostructures produced by laser processing. Figure 2 and Figure 4 At medium to high concentrations, some sharp peaks become rounded.

[0036] like Figure 3 and Figure 5 As shown, for the two sets of laser parameters, although the unmodified samples had a certain roughness after laser processing, their contact angles (125.1° and 110.5°) did not meet the superhydrophobic standard. After stearic acid modification, the roughness generally showed a trend of decreasing and then increasing, while the contact angle of all samples was significantly improved. This indicates that stearic acid chemical modification is the decisive step in improving surface hydrophobicity.

[0037] like Figure 3 As shown in (a), Group A uses lower power and a larger scanning interval, resulting in a relatively mild laser energy input and less material removal. Therefore, its initial surface roughness (Sa) of 0.995 μm and line roughness (Ra) of 0.756 μm are low, forming a relatively flat, low-undulation micron-scale structure substrate. Figure 5(a) Group B, using high power and small spacing parameters, has high energy density and high scan line overlap, leading to intense material melting, vaporization, and recasting. Therefore, its initial Sa (4.71 μm) and Ra (4.481 μm) are much higher than Group A, resulting in an extremely rough morphology rich in slag and micro-pits. The roughness of both groups generally shows a trend of first decreasing and then increasing, but the overall change is not significant. The difference in Sa for Group A does not exceed 13.7%, and the difference in Ra does not exceed 8.7%, while the differences for Group B do not exceed 0.8% and 5.3%, respectively.

[0038] For group A parameters, the contact angle showed a nearly monotonically increasing trend with increasing stearic acid concentration. The increase was significant, rising from 133.1° at 0.01 mol / L to 146.2° at 0.2 mol / L. This indicates that in microstructures generated under lower laser parameters, higher concentrations of stearic acid are more effective at reducing surface energy, and no inflection point in performance degradation due to excessively high concentrations was observed. The contact angle for group B parameters also increased with increasing concentration, rising from 122.9° at 0.01 mol / L to 133.8° at 0.2 mol / L.

[0039] Within the concentration range (0-0.2 mol / L) set in this experiment, higher stearic acid concentrations resulted in higher contact angles for both studied surface structures. Surface in parameter group A exhibited optimal hydrophobicity (146.2°) at 0.2 mol / L, while parameter group B also reached its peak at 0.2 mol / L (133.8°). For both parameter groups, the contact angle increases at 0.1 mol / L and 0.2 mol / L were 16.1% and 16.9% for group A, and 19.9% ​​and 21% for group B, respectively, indicating that the modification performance of the two concentrations was very similar. In conclusion, considering both economic efficiency and the need to avoid potential disordered multilayer stacking, a 0.1 mol / L stearic acid-ethanol solution was ultimately determined as the optimal concentration of the chemical modifier.

[0040] Example 5: This example investigates the influence of laser process parameters on surface properties. The specific steps are as follows: I. Effect of the number of scans on surface morphology and wettability The number of scans is one of the key parameters in femtosecond laser processing, directly determining the cumulative effect of laser energy in the same region of the material, thus significantly affecting the final surface morphology and properties. This experiment investigated the influence of the number of scans (2, 3, 4, and 5) on the surface microstructure and wettability of 316L stainless steel under two sets of basic laser parameters (Group A: power 6 W, scanning speed 500 mm / s, scanning spacing 75 μm; Group B: power 12 W, scanning speed 500 mm / s, scanning spacing 50 μm).

[0041] Figure 6 These are 3D morphology images of the surface of 316L stainless steel under different scan numbers in Group A. Figure 7 Figure A shows the surface quality parameters of 316L stainless steel under different scan numbers, where (a) shows the surface roughness and (b) shows the contact angle and machining depth. Figure 8 These are 3D morphology images of the surface of 316L stainless steel under different scan numbers in Group B. Figure 9 Figure B shows the surface quality parameters of 316L stainless steel under different scan numbers, where (a) shows the surface roughness and (b) shows the contact angle and machining depth.

[0042] like Figure 6 and Figure 8 As shown, with increasing scan counts, the laser repeatedly ablates, melts, and recasts the material, leading to a regular evolution of the surface morphology. After two scans, the surface exhibits shallow and sparse parallel grooves and micro-protrusions, with incomplete structural development, a smooth overall surface, and a monotonous morphology. With increasing scan counts, the grooves deepen and widen, the micro-protrusions become more pronounced and denser, secondary structures begin to appear, surface roughness increases significantly, and the three-dimensional effect is enhanced. By the fourth and fifth scans, the microstructure is fully developed and regular, forming a clear and uniform array of periodic microgrooves / microridges. The morphology of the groove bottoms and ridge tops tends to stabilize, achieving an optimal balance between roughness and structural order.

[0043] like Figure 7 and Figure 9 As shown, in group A, both Sa and Ra increased monotonically with increasing scan count, from 0.52 μm and 0.38 μm to 1.11 μm and 1.84 μm, respectively. The processing depth also increased synchronously, from 4.17 μm after 2 scans to 9.63 μm after 5 scans, and then increased sharply after 4 scans. This indicates that at lower power, increasing the number of scans can effectively and progressively deepen and roughen the surface structure. For group B, the morphological evolution was more complex. Sa showed a monotonically increasing trend, rising sharply to 5.36 μm after 5 scans. Ra showed its first peak of 2.16 μm after 3 scans, decreased slightly to 1.51 μm after 4 scans, and then jumped sharply to a very high value of 4.29 μm after 5 scans. This non-monotonic change indicates that the effect of the number of scans at high power is phased: in the early stage, it is mainly effective ablation and structural shaping; in the middle stage, it may be accompanied by partial filling of the groove by the molten material, making the surface relatively homogenized; in the later stage, due to excessive energy accumulation, it leads to violent material splashing and recasting, which easily forms an extremely rough and irregular slag accumulation morphology.

[0044] The contact angles of the two sets of parameters are as follows Figure 7 (b) and Figure 9As shown in (b), the contact angle of group A first increases and then decreases with the number of scans, reaching a peak of 125.1° at 4 scans. At 2 scans, the structure is underdeveloped and hydrophilic; at 4 scans, the moderate roughness amplifies the material's inherent weak hydrophobicity through the Wenzel effect; at 5 scans, although the roughness is highest, excessive high-surface-energy molten oxide residues may have been generated, which actually enhances the intrinsic hydrophilicity, causing the contact angle to decrease to 114.6°. The contact angle of group B shows a similar trend to group A, but with greater numerical fluctuations. It reaches a peak of 137.1° at 4 scans and also exhibits relatively high hydrophobicity (136.3°) at 3 scans. However, at 5 scans, the contact angle deteriorates sharply to 107.1°. This again confirms that excessive scanning produces extreme morphologies (such as excessively deep pores and a large amount of slag), which are detrimental to obtaining excellent inherent hydrophobicity.

[0045] After modification with 0.1 mol / L stearic acid, the contact angles of all samples were significantly improved, demonstrating the crucial role of the low surface energy coating. In Group A, the sample in 4 scans achieved the highest contact angle of 145.2°, exhibiting excellent hydrophobicity. The samples in 2 and 3 scans showed limited improvement in contact angle after modification due to their lower basic roughness (117.7° and 131.4°, respectively). The sample in 5 scans had a contact angle of only 120.8° after modification, suggesting that its unfavorable surface chemistry may have hindered the formation of a high-quality stearic acid monolayer. Group B showed a highly significant performance improvement after modification; the samples in 3 and 4 scans both achieved superhydrophobicity (>150°), with the sample in 4 scans achieving the highest contact angle of 158.7°. This is attributed to the complex micro / nano structure formed under high power and homogenized to a certain extent (4 scans), which provided an ideal anchor point for the Cassie state, and whose surface chemistry was more easily modified by stearic acid. The contact angle of the sample after 5 scans was only 125.7°, and its overly chaotic morphology was not conducive to the formation of a stable air cushion.

[0046] In summary, combining morphological data and wettability test results, it can be clearly concluded that 4 scans are the optimal number of scans.

[0047] II. Effect of Scanning Speed ​​on Surface Morphology and Wettability Scanning speed is one of the key process parameters affecting the surface structure of femtosecond laser processing, directly influencing the interaction time between the laser and the material, energy accumulation, and material removal mechanism. This section systematically studies the morphological characteristics and wettability changes of 316L stainless steel surfaces at different scanning speeds, revealing its influence on the construction of surface micro / nano structures and superhydrophobic properties.

[0048] Figure 10 The images show 3D morphology images of the surface of 316L stainless steel at different scanning speeds for Group A. Figure 11The surface quality parameters of 316L stainless steel in Group A are shown at different scanning speeds, where (a) shows the surface roughness and (b) shows the contact angle and machining depth. Figure 12 The images show 3D morphology of the 316L stainless steel surface at different scanning speeds in Group B. Figure 13 The surface quality parameters of 316L stainless steel in Group B at different scanning speeds are shown, where (a) shows the surface roughness and (b) shows the contact angle and machining depth.

[0049] from Figure 10 and Figure 12 It can be observed that as the scanning speed increases, the regularity and uniformity of the surface microstructure are enhanced, the slag and remelting phenomena are reduced, and the surface tends to be smooth. Figure 11 and Figure 13 Further quantitative analysis was conducted on the variation trends of surface roughness, contact angle, and processing depth. At a scanning speed of 500 mm / s, a relatively optimal balance was achieved between surface roughness and contact angle, and a moderate processing depth was found, which is beneficial for constructing stable micro / nano composite structures with gradient characteristics.

[0050] Experimental results show that the surface roughness of the samples generally decreases with increasing scanning speed. When the scanning speed increases from 300 mm / s to 600 mm / s, the surface line roughness of group A decreases from 1.03 μm to 0.67 μm, and the surface roughness decreases from 1.43 μm to 0.78 μm; while the surface line roughness of group B decreases from 5.39 μm to 1.92 μm, and the surface roughness decreases from 6.14 μm to 1.92 μm. After stearic acid modification, the contact angle is significantly improved. At a scanning speed of 500 mm / s, the contact angle of the modified surface of group A reaches 142.7°, which is not much different from 143° at 600 mm / s. Group B, at a scanning speed of 500 mm / s, achieves a contact angle of 158.7°, exhibiting excellent superhydrophobic properties and perfectly meeting the superhydrophobic process requirements of this study.

[0051] Comprehensive analysis shows that scanning speed affects surface melting behavior, microprotrusion distribution, and secondary structure formation by regulating laser energy input and material response time. Too low a speed results in excessive energy input, easily causing over-melting and surface inhomogeneity; too high a speed may lead to insufficient energy, incomplete microstructure development, and compromised superhydrophobic properties. A scanning speed of 500 mm / s achieves a balance between surface morphology uniformity, suitable roughness, and high contact angle within the experimental parameter range, making it the optimal scanning speed for preparing gradient superhydrophobic stainless steel surfaces.

[0052] III. Effects of Laser Power and Scanning Spacing on Surface Morphology and Wettability 1. Effect of different scanning intervals on surface morphology and wettability at a laser power of 3W Figure 14 The surface quality parameters of 316L stainless steel at different scanning intervals with a laser power of 3W are shown, where (a) is the surface roughness and (b) is the contact angle and machining depth. Figure 14 As shown in (a), without chemical modification, the surface linear roughness (Ra) initially increases and then decreases as the scanning spacing increases from 25 μm to 150 μm, reaching a peak of 0.629 μm at a spacing of 75 μm, and then decreasing to approximately 0.462 μm at a spacing of 150 μm. The surface roughness (Sa) shows a similar trend, with a maximum value of 0.809 μm at a spacing of 75 μm. After chemical modification, the roughness values ​​change only slightly at most spacings; for example, at a spacing of 75 μm, the modified linear roughness is 0.607 μm, and the average surface roughness is 0.833 μm, still maintaining a relatively high level. This indicates that at 3W power, a medium scanning spacing (75 μm) is beneficial for forming certain microstructure undulations.

[0053] like Figure 14 As shown in (b), the processing depth did not exhibit a single trend with increasing scanning spacing, fluctuating between 1.872 μm and 2.327 μm. The contact angle of the unmodified surface fluctuated with increasing spacing, reaching its highest value at a scanning spacing of 50 μm (119.03°), while rapidly decreasing to 84.1° and even 76.23° at scanning spacings of 125 μm and 150 μm, indicating a tendency towards hydrophilicity. After stearic acid modification, the contact angle at all scanning spacings was significantly improved, generally ranging from 121.33° to 142.53°, reaching a maximum of 142.53° at a scanning spacing of 75 μm. This indicates that at 3W power, using a scanning spacing of around 75 μm supplemented with chemical modification can achieve superior superhydrophobic properties (contact angle > 140°), with the surface exhibiting moderate roughness and stable hydrophobic characteristics under these conditions.

[0054] 2. Effects of different scanning intervals on surface morphology and wettability at a laser power of 6W Figure 15 The surface quality parameters of 316L stainless steel at different scanning intervals with a laser power of 6W are shown, where (a) is the surface roughness and (b) is the contact angle and machining depth. Figure 15 As shown in (a), the line roughness of the unmodified surface is relatively high at a scanning spacing of 25 μm, reaching 1.355 μm, and gradually decreases with increasing scanning spacing, reaching 0.482 μm at 150 μm. The surface roughness exhibits a similar trend, reaching 1.142 μm at a scanning spacing of 25 μm, and then gradually decreasing. The roughness value remains generally unchanged after modification, with only slight variations at certain spacings.

[0055] like Figure 15As shown in (b), the average sample depth ranged from 5.205 μm to 6.171 μm. The contact angle of the unmodified surface peaked at 125.07° at a scanning interval of 75 μm, but decreased significantly to 82.07° at a larger scanning interval of 150 μm. The contact angle generally improved after modification, ranging from 122.23° to 142.7°, with the modified surface at a 75 μm interval exhibiting the highest contact angle of 142.7°. This indicates that at 6 W power, a 75 μm scanning interval combined with chemical modification can create a surface that combines a certain degree of roughness with good hydrophobicity, and the contact angle meets the requirements for superhydrophobicity.

[0056] 3. Effects of different scanning intervals on surface morphology and wettability at a laser power of 9W Figure 16 The surface quality parameters of 316L stainless steel at different scanning intervals with a laser power of 9W are shown, where (a) is the surface roughness and (b) is the contact angle and machining depth.

[0057] When the laser power is further increased to 9W, the influence of the scanning spacing on surface features exhibits new patterns. For example... Figure 16 As shown in (a), the unmodified surface exhibits an abnormally high linear roughness of 3.608 μm and a surface roughness of 4.549 μm at a scanning interval of 25 μm, indicating that the excessively dense scanning leads to a significant thermal accumulation effect, resulting in a relatively rough fused surface. With increasing scanning interval, the roughness decreases rapidly, reaching an average linear roughness of only 0.458 μm at 150 μm. The roughness remains essentially unchanged after modification.

[0058] like Figure 16 As shown in (b), compared with a laser power of 6W, the processing depth further increased, with the sample depth ranging from 10.276μm to 10.912μm, showing no clear monotonic trend. This may be related to the complexity of the molten pool flow and solidification process at higher power. The unmodified surface exhibited high contact angles at scanning intervals of 50μm and 75μm, with average values ​​of approximately 134.67° and 130.7°, respectively, demonstrating some hydrophobicity. However, when the interval was greater than or equal to 100μm, the contact angle dropped sharply to below 85.37°. The modified surface showed a significant improvement in contact angle, reaching a maximum of 149.47° at a 50μm interval, approaching the upper limit of superhydrophobicity; the average contact angle at a 75μm interval was also as high as approximately 146°. This indicates that at 9W power, using scanning intervals of 50-75μm and chemical modification, high-performance superhydrophobic surfaces with contact angles greater than 145° can be achieved.

[0059] Effects of different scanning intervals on surface morphology and wettability at a laser power of 12W Figure 17The surface quality parameters of 316L stainless steel at different scanning intervals with a laser power of 12W are shown, where (a) is the surface roughness and (b) is the contact angle and machining depth.

[0060] At the highest test power of 12W, the interaction between the laser and the material was most intense, and the surface morphology and wettability exhibited a significant energy accumulation effect. For example... Figure 17 As shown in (a), the surface roughness of the unmodified surface reaches its maximum value (4.481 μm for line roughness and 4.71 μm for surface roughness) at a scanning interval of 25 μm. As the interval increases, the roughness decreases rapidly, with the line roughness and surface roughness decreasing to 0.48 μm and 0.741 μm, respectively, at 150 μm. The roughness change after chemical modification is not significant, and the overall trend is similar to that at a laser power of 9 W.

[0061] like Figure 17 As shown in (b), at a laser power of 12W, the processing depth significantly increases compared to low power, falling within the high range of 18.464μm to 20.49μm, indicating that high power can produce a strong ablation effect, forming a deep groove structure. The unmodified surface exhibits the highest contact angle at a scanning spacing of 50μm, reaching 137.1°, which then decreases with increasing spacing, reaching only 77.03° at 150μm. The hydrophobicity of the modified surface is significantly improved, with the contact angle at a scanning spacing of 50μm reaching approximately 158.67°, demonstrating excellent superhydrophobic properties; the contact angles at other spacings are mostly above 130°. It is evident that at 12W power, a 50μm scanning spacing combined with chemical modification represents the optimal process window for achieving superhydrophobicity (contact angle >158°).

[0062] Example 6: Determination of Optimal Processing Technology Based on the single-factor experimental results of Examples 4 and 5, the process parameters were optimized through a four-factor, three-level orthogonal experiment. Using contact angle and roll-off angle as evaluation indicators, the optimal process combination for preparing biomimetic microtextures on the surface of surgical instruments using femtosecond laser was determined to be: laser power 12W, scanning speed 500mm / s, scanning spacing 50μm, and 4 scans. Subsequently, the surface was chemically modified with 0.1mol / L stearic acid ethanol solution (immersion for 30min, curing at 120℃ for 1h) to further reduce the surface energy and improve the superhydrophobic properties.

[0063] In this embodiment, following the optimal process described above, papillary biomimetic microtexture samples were prepared on the surfaces of three materials: 316L stainless steel, 420 stainless steel, and TC4 titanium alloy. After pretreatment (grinding, ethanol wiping, ultrasonic cleaning for 10 minutes, and drying), laser processing, and chemical modification, the samples were placed in an environment of 25°C and 50% humidity for standby. Three sets of parallel samples were prepared for repeatability verification of performance testing.

[0064] Superhydrophobic performance test: Using a contact angle meter, 5 μL of deionized water was added, and three test points were randomly selected on the sample surface to measure the static contact angle and roll-off angle. The average value was taken. Figure 18 As shown.

[0065] Morphological characterization: The micro-morphology of the micro-texture on the sample surface was observed using SEM, and the surface roughness (Sa, Ra) was measured using laser confocal scanning microscopy.

[0066] After processing with the optimal process, a surface with a surface roughness test result of Sa=4.71μm and Ra=4.48μm was successfully prepared, meeting the roughness requirements of a superhydrophobic surface. The contact angle of all samples was ≥150° and the roll-off angle was ≤20°, meeting the specified technical indicators and indicating good process repeatability.

[0067] In summary, this invention overcomes the limitations of traditional superhydrophobic surface preparation, which focuses solely on wettability, by combining the micro / nano structure construction achieved through ultrafast laser processing with the surface energy modulation of medical metal materials. Utilizing the low thermal effect of femtosecond lasers, precise micro / nano-hierarchical rough structures are constructed on medical metal surfaces. Chemical modification with stearic acid alters only the molecular-level energy states of the material surface without affecting the mechanical strength of the substrate itself, thus resolving the technical challenge of the conflict between superhydrophobic modification and the medical performance of surgical instruments.

[0068] The above embodiments fully illustrate the feasibility, parameter effects, and technical advantages of the method of the present invention. Those skilled in the art can make adaptive adjustments to the substrate material, laser parameters, structural dimensions, or modification conditions within the scope defined in the claims, and all such adjustments fall within the protection scope of the present invention.

Claims

1. A method for surface processing of medical metal instruments with anti-adhesion properties, characterized in that, Includes the following steps: S1. Pre-treat the substrate surface of medical metal instruments; S2. A femtosecond laser is used to scan and etch the pretreated substrate surface to construct a biomimetic microtexture with micron-level structural features and nanon-level roughness on the substrate surface. S3. The surface treated in step S2 is immersed in a stearic acid ethanol solution for chemical modification to form a hydrophobic molecular layer on the biomimetic microtexture surface, thereby obtaining a superhydrophobic and anti-adhesion surface.

2. The surface processing method for medical metal devices with anti-adhesion properties according to claim 1, characterized in that, In step S2, the biomimetic microtexture is selected from at least one of papillary structure or mesh structure; the micron-level structural features include: the base diameter of the papilla in the papillary structure is 5-9 μm and the height is 4-8 μm, or the width of the groove in the mesh structure is 40-60 μm, the depth is 6-10 μm, and the mesh spacing is 40-60 μm.

3. The surface processing method for medical metal instruments with anti-adhesion properties according to claim 1, characterized in that, In step S2, the wavelength of the femtosecond laser is 1064 nm.

4. The surface processing method for medical metal instruments with anti-adhesion properties according to claim 1 or 3, characterized in that, In step S2, the processing parameters of the femtosecond laser are: laser power of 9-12W, scanning speed of 300-600mm / s, number of scans of 3-5, and scanning interval of 25-75μm.

5. The surface processing method for medical metal instruments with anti-adhesion properties according to claim 4, characterized in that, In step S2, the processing parameters of the femtosecond laser are: laser power 12W, scanning speed 500mm / s, number of scans 4, and scanning interval 50μm.

6. The surface processing method for medical metal instruments with anti-adhesion properties according to claim 1, characterized in that, In step S3, the concentration of the stearic acid ethanol solution is from 0.05 mol / L to 0.2 mol / L.

7. The surface processing method for medical metal instruments with anti-adhesion properties according to claim 6, characterized in that, In step S3, the concentration of the stearic acid ethanol solution is 0.1 mol / L.

8. The method for surface processing of medical metal instruments with anti-adhesion properties according to claim 1, 6, or 7, characterized in that, In step S3, the soaking time is 20 to 40 minutes; after the soaking treatment, a heat treatment curing step is also included, wherein the heat treatment curing temperature is 100 to 140°C and the time is 0.5 to 2 hours.

9. The surface processing method for medical metal instruments with anti-adhesion properties according to claim 1, characterized in that, The pretreatment in step S1 includes: sequentially grinding, cleaning with ethanol, ultrasonic cleaning, and drying the substrate surface.

10. The surface processing method for medical metal instruments with anti-adhesion properties according to claim 1, characterized in that, The base material of the medical metal device is selected from 316L stainless steel, 420 stainless steel or TC4 titanium alloy.

Images