Design and preparation method of lotus seedpod type titanium alloy surface super-hydrophobic microstructure

Abstract

The invention discloses a design and preparation method of a lotus seedpod type titanium alloy surface super-hydrophobic microstructure. The super-hydrophobic function is achieved by designing the lotus seedpod-shaped structures and the pit structures which are periodically arranged, and preparation is conducted through the femtosecond laser and the magnetron sputtering technology. The designed super-hydrophobic microstructure can present a good super-hydrophobic function, can effectively store air to form an air film layer, and realizes antibiosis by a physical isolation method, so that the bone implant obtains the ability of resisting bacterial adhesion and biofilm formation. And based on the lotus seedpod-shaped structure and pit composite structure characteristics, a mathematical equation is deduced in combination with a liquid drop infiltration model, characteristic parameters of the corresponding super-hydrophobic microstructure when the contact angle is larger than 150 degrees are determined, and super-hydrophobic microstructure design is completed. A Ti6Al4V titanium alloy material is selected for polishing pretreatment, a lotus seedpod-shaped structure and a pit structure are etched on the surface of the polished titanium alloy by utilizing the characteristics of femtosecond laser, and a TiO2 coating is deposited on the surface of the microstructure through magnetron sputtering, so that the preparation of the super-hydrophobic surface is realized. The design method provided by the invention can provide a systematic design theory and a realizable process scheme for surface functionalization of the bone implant.

Description

Technical Field

[0001] This invention belongs to the field of superhydrophobic structure design for bone implant surfaces, and particularly relates to a lotus-shaped titanium alloy surface superhydrophobic microstructure design and a preparation method based on femtosecond laser and magnetron sputtering. The designed lotus-shaped structure and pit structure can exhibit superhydrophobic function, and the microstructure can effectively retain air to form an air film layer, thereby achieving antibacterial effect through physical isolation, enabling the bone implant to acquire the ability to resist bacterial adhesion and biofilm formation. Background Technology

[0002] Titanium alloy Ti6Al4V has become the mainstream material for bone implants due to its high strength, corrosion resistance, low density, and biocompatibility. However, the interaction between titanium alloy implants and the human body environment makes their surfaces prone to bacterial biofilm growth, leading to persistent infections and inflammation. Superhydrophobic surfaces, through their extremely low surface energy and micro / nano rough structures, can significantly inhibit the initial adhesion of proteins, bacteria, and fibroblasts, reducing the risk of infection at its source and minimizing fibrous encapsulation. Simultaneously, the air layer trapped on the surface can form a physical barrier, delaying metal corrosion and ion release, and improving long-term biocompatibility. Furthermore, this property can reduce platelet and non-specific protein adhesion, lowering the risk of thrombosis and creating a favorable healing microenvironment for bone integration. Therefore, endowing its surface with superhydrophobic properties has become a necessary surface modification strategy and has attracted widespread attention from researchers. With the continuous advancement of research, the preparation of superhydrophobic surfaces of titanium alloys mainly focuses on constructing micro / nano composite structures on the titanium alloy surface. The design of micro-nano composite structures is key to achieving superhydrophobicity in titanium alloys. Their size, morphology, and distribution have a significant impact on the wetting state and contact behavior of droplets on the surface, thus affecting their superhydrophobic properties. Therefore, the design and fabrication of superhydrophobic micro-nano composite structures for titanium alloys are particularly important.

[0003] Superhydrophobic surfaces refer to material surfaces where the contact angle of a water droplet is greater than 150° and the roll-off angle is less than 10°. They have significant application value in self-cleaning, corrosion prevention, and anti-frost applications. The contact angle generated by a droplet on a solid surface is an important indicator of wetting properties. The contact angle is the result of the surface tension balance between the solid, liquid, and gas interfaces. When the tension is balanced, the total energy of the system tends to be at its lowest, and the droplet on the solid surface is in a stable state. The microstructure is a key factor affecting the high contact angle of water droplets on material surfaces. Therefore, the preparation of superhydrophobic surfaces mainly involves modifying rough surfaces with microstructures with low surface energy materials, or constructing microstructures on the surface of low surface energy materials. With the continuous exploration of surface modification technologies, femtosecond laser processing technology, due to its high precision, non-contact nature, and controllability, is widely used in the processing of surface microstructures.

[0004] Invention patent 202111208355.6 discloses a method for laser-induced highly bioactive surfaces of oral titanium alloy implants. It utilizes ultrafast lasers to fabricate micro / nano structures on the titanium alloy surface, improving the bioactivity of oral titanium alloy implants and reducing rejection reactions in the oral cavity. However, this method only involves laser etching to create microstructures, and the etched structures lack superhydrophobic properties, making it relatively less functional compared to the present invention. Invention patent 202211646389.8 discloses a method for preparing multi-level micron-sized structures on the surface of 3D-printed bone implants. It uses 3D printing technology to print titanium alloy bone implants with micron-sized porous structures on their surface, which can improve surface bioactivity and promote bone formation. However, the porous structures involved lack a specific shape, have relatively limited functionality, and the preparation process is complex.

[0005] In summary, existing research on the design and fabrication of superhydrophobic microstructures on the surface of titanium alloy bone implants is limited, and current designs fall short in terms of air retention and reducing contact area. Therefore, this invention presents a method for designing and fabricating lotus-shaped superhydrophobic microstructures on the surface of titanium alloys. This method utilizes periodically arranged lotus-shaped structures and pitted structures to achieve superhydrophobic functionality, and employs femtosecond laser and magnetron sputtering techniques for fabrication. This lotus-shaped superhydrophobic microstructure design and fabrication method for the surface functionalization of bone implants provides a systematic design theory and feasible process solution, possessing significant application value and practical significance. Summary of the Invention

[0006] This invention provides a method for designing and fabricating a lotus-shaped titanium alloy surface superhydrophobic microstructure. The method utilizes a periodic arrangement of lotus-shaped and pitted microstructures to achieve superhydrophobic functionality. Based on a wetting model where droplets are in a relatively low-energy, more stable state on the superhydrophobic surface, numerical equations are derived and established to determine the microstructure characteristic parameters corresponding to a contact angle greater than 150°, thus completing the superhydrophobic microstructure design. The method involves pre-polishing Ti6Al4V titanium alloy material, using the characteristics of a femtosecond laser to etch the lotus-shaped and pitted structures onto the polished titanium alloy surface, and then depositing a TiO2 coating on the microstructure surface via magnetron sputtering, thereby achieving the fabrication of the superhydrophobic surface. The technical solution adopted in this invention is: a method for designing and fabricating a lotus-shaped titanium alloy surface superhydrophobic microstructure, characterized by the following steps.

[0007] Step 1: Design the microstructure of the superhydrophobic surface, which consists of periodically arranged lotus seedpod-shaped structures and pit structures.

[0008] Step 2: Based on the droplet wetting model, derive the mathematical equations and establish the numerical relationship between the structural characteristic parameters of the lotus-shaped structure and the pit and the superhydrophobic function, i.e., the water droplet contact angle. , In the formula: θ T and θ c These represent the theoretical contact angle and the intrinsic contact angle, respectively. The intrinsic contact angle of a water droplet on a smooth surface is... θ c The angle is 100° to 110°. R t , R fb , R ft , R p , R These are the radius of the deep pit, the bottom radius of the lotus-shaped structure, the top radius of the lotus-shaped structure, the top recess of the lotus-shaped structure, and the radius of the recess. D The spacing of the microstructure; λ The wetting coefficient is the degree to which a water droplet wets a microstructure. It is the coefficient of water droplet concentration when the droplet floats on top of the microstructure. λ =0, when the water droplet completely wets the microstructure λ =1; The original numerical equations were used to determine the microstructure characteristic parameters corresponding to a water droplet contact angle greater than 150°, thus completing the design of the superhydrophobic microstructure.

[0009] Step 3: Select titanium alloy Ti6Al4V for surface polishing treatment to achieve a surface roughness of 0.8 μm. Then clean it and place it in a constant temperature oven at 40℃ for 30 min to dry the polished Ti6Al4V surface.

[0010] Step 4: The polished and dried Ti6Al4V surface is subjected to femtosecond laser etching to prepare a composite microstructure composed of periodically arranged lotus seedpod-shaped structures and pits.

[0011] Step 5: Select a high-purity TiO2 target (purity ≥ 99.9%), control the distance between the target and the sample to 5–8 cm, and use magnetron sputtering to deposit a 50 nm TiO2 coating on the laser-etched Ti6Al4V surface to obtain a Ti6Al4V superhydrophobic surface.

[0012] Step 1 specifically includes: The design incorporates a periodically arranged lotus-shaped structure and a pitted structure. When droplets wet the superhydrophobic microstructure, the lotus-shaped and pitted structures effectively trap air, forming an air film to achieve superhydrophobicity, while simultaneously providing antibacterial and anti-adhesion effects through physical isolation.

[0013] Step 2 specifically includes: (1) The designed lotus-shaped structure and pit structure have micron-level structural characteristic parameters, among which the radius of the deep pit is...R t Designed to be 40-50 μm, Lotus seedpod-shaped structure bottom radius R fb Designed with a top radius of 30-40 μm for the lotus-shaped structure. R ft Designed to be 10-15 μm, The lotus-shaped structure has a concave top. R p Designed to have a pit radius of 5-10 μm. R Designed to be 15-20 μm; microstructure spacing D Designed for 90-110 μm; (2) Substitute the structural characteristic parameters of the lotus seed pod structure and the pit structure into the mathematical equation to calculate the theoretical value of the water droplet contact angle. Determine whether it has superhydrophobic function based on whether the contact angle is greater than 150°, realize the controllable design of superhydrophobic surface, and clarify the characteristic parameters of superhydrophobic microstructure.

[0014] 4. The method for designing and preparing a superhydrophobic microstructure on the surface of a lotus-shaped titanium alloy according to claim 1, characterized in that step 3 specifically includes: (1) Select Ti6Al4V titanium alloy as the matrix material for superhydrophobic microstructure and cut it into square samples of 2 cm × 2 cm. (2) Polish the surface of the Ti6Al4V sample to obtain a smooth surface with a roughness of 0.8 μm; (3) The polished Ti6Al4V sample was ultrasonically cleaned in anhydrous ethanol for 3 min, and then placed in a constant temperature oven and dried at 40℃ for 30 min to remove the impurities and moisture remaining on the sample surface.

[0015] 5. The method for designing and preparing a superhydrophobic microstructure on the surface of a lotus-shaped titanium alloy according to claim 1, characterized in that step 4 specifically includes: (1) Place the polished and dried Ti6Al4V sample on the femtosecond laser system platform, adjust the laser focus to the sample surface, and determine the laser scanning path based on the superhydrophobic microstructure characteristic parameters determined in step 2. (2) Set the femtosecond laser processing parameters: laser power 3 W, beam radius 10 μm, pulse duration 600 fs, laser wavelength 515 nm, laser frequency 300 KHz; (3) The lotus-shaped structure and pit structure are processed by multiple etchings on the sample surface by femtosecond laser.

[0016] 6. The method for designing and preparing a superhydrophobic microstructure on the surface of a lotus-shaped titanium alloy according to claim 1, characterized in that step 5 specifically includes: (1) Select high-purity TiO2 target material (purity ≥ 99.9%), and control the distance between the target material and the sample at 5–8 cm to ensure the uniformity of the coating. (2) Magnetron sputtering deposition was performed on the surface of the Ti6Al4V sample after laser etching. The stage speed was set to 5 r / min to ensure the uniformity of the coating. After 2 h of deposition, a TiO2 coating with a thickness of 50 nm was obtained, and finally the Ti6Al4V superhydrophobic surface was obtained.

[0017] This invention discloses a method for designing and fabricating a superhydrophobic microstructure on a lotus-shaped titanium alloy surface. The superhydrophobic function relies on the lotus-shaped structure and the pitted structure. Based on a theoretical model of droplet-wetting superhydrophobic microstructures, mathematical equations are derived to clarify the characteristic parameters of the composite structure corresponding to a contact angle greater than 150°, thus completing the superhydrophobic microstructure design. Leveraging the advantages of femtosecond lasers—high precision, controllability, flexibility, and efficiency—the lotus-shaped structure and the pitted structure are etched onto the polished titanium alloy surface. A TiO2 coating is then deposited on the microstructure surface via magnetron sputtering, thereby achieving the fabrication of the superhydrophobic surface. This design method provides a systematic design theory and feasible process scheme for the functionalization of bone implant surfaces. Attached Figure Description

[0018] Figure 1 A schematic diagram of the overall structure of the present invention; Figure 2 Schematic diagram of the lotus-shaped structure and the recessed structure of the present invention; Figure 3 A schematic diagram of femtosecond laser processing and magnetron sputtering in this invention; Figure 4 A schematic diagram of a femtosecond laser-etched sample obtained by scanning electron microscopy. Figure 5 Schematic diagram of the Ti6Al4V sample of the present invention; Figure 6 Contact angle test diagram of Ti6Al4V sample of the present invention; In the diagram: 1. Lotus seedpod-shaped structure; 1-1. Top recess of the lotus seedpod-shaped structure; 1-2. Outer wall of the lotus seedpod-shaped structure; 2. Base; 3. Recess. Detailed Implementation

[0019] The following embodiments are used to illustrate the present invention, but are by no means intended to limit the scope of the present invention. The working process of the present invention will be described in detail below with reference to the accompanying drawings.

[0020] This invention discloses a method for designing and fabricating a lotus-shaped superhydrophobic microstructure on a titanium alloy surface. The design process involves: designing the superhydrophobic surface microstructure as a periodically arranged lotus-shaped structure and a pitted structure; obtaining original numerical equations for the superhydrophobic microstructure and its superhydrophobic function based on a theoretical model of droplet wetting; and clarifying the characteristic parameters of the superhydrophobic microstructure corresponding to a contact angle greater than 150°. Ti6Al4V titanium alloy material is selected for polishing pretreatment. The lotus-shaped structure and pitted structure are etched onto the polished titanium alloy surface using the characteristics of a femtosecond laser. A TiO2 coating is then deposited on the microstructure surface by magnetron sputtering, thereby achieving the fabrication of the superhydrophobic surface. The specific steps of this invention's method for designing and fabricating a lotus-shaped superhydrophobic microstructure on a titanium alloy surface are as follows.

[0021] 1. Design the microstructure of the superhydrophobic surface, which consists of periodically arranged lotus seedpod-shaped structures and pit structures, specifically including: The design incorporates a periodically arranged lotus-shaped structure and a recessed structure, such as... Figure 1 As shown, when droplets wet the superhydrophobic microstructure, the lotus-shaped structure and the pitted structure can effectively trap air, forming an air film layer to achieve superhydrophobic function, while simultaneously achieving antibacterial and anti-adhesion through physical isolation.

[0022] 2. Based on the theoretical model of droplet-wetting superhydrophobic microstructures, an original numerical equation between the superhydrophobic microstructure and its superhydrophobic function (wettability) is derived and established. The characteristic parameters of the microstructure corresponding to a droplet contact angle greater than 150° are defined, and the design of the superhydrophobic microstructure is completed, specifically including: (1) The designed lotus-shaped structure and pit structure have micron-level structural characteristic parameters, among which the radius of the deep pit is... R t Designed to be 40-50 μm, Lotus seedpod-shaped structure bottom radius R fb Designed with a top radius of 30-40 μm for the lotus-shaped structure. R ft Designed to be 10-15 μm, The lotus-shaped structure has a concave top. R p Designed to have a pit radius of 5-10 μm. R Designed to be 15-20 μm; microstructure spacing D Designed for 90-110 μm, such as Figure 2 As shown; (2) Based on the wetting state model of droplets in a relatively low-energy and more stable state on a superhydrophobic surface, an original numerical equation between superhydrophobic microstructure and superhydrophobic function, i.e., wettability, is derived and established. The Cassie-Baxter wetting model assumes that when a droplet wets a solid surface, it can trap air in the microstructure of the solid surface. Therefore, the contact surface consists of three parts: droplet, air, and solid surface microstructure. Based on this, the Cassie-Baxter equation is proposed: , In the formula, θ T It is the contact angle, θ c It is the intrinsic contact angle, f s1 It is the ratio of the actual wetted solid area of ​​the droplet to the apparent geometric contact area. f r This represents the roughness coefficient, i.e., the degree of surface roughness. It is also the projected area per unit microstructure. S P It can be calculated using formula (2): , Actual surface area generated by unit microstructure S S It consists of two parts: a lotus-shaped structure 1 and a recessed area 2. The value is calculated using the following formula. , In the formula, R t , R fb , R ft , R p , R These are the radius of the deep pit, the bottom radius of the lotus-shaped structure, the top radius of the lotus-shaped structure, the top recess of the lotus-shaped structure, and the radius of the recess. D The spacing of the microstructure; Based on this roughness coefficient f r It can be represented as: , When water droplets wet the designed superhydrophobic microstructure, varying degrees of wetting occur, thus requiring the introduction of a wetting coefficient. λ This indicates the degree to which the water droplet wets the microstructure; when the water droplet only wets the top of the microstructure... λ =0, when the water droplet completely wets the microstructure. λ =1, therefore 0≤ λ≤1; To achieve good superhydrophobicity in the designed superhydrophobic surface, the water droplet contact angle must be greater than 150°. This means that the water droplet has a relatively small wetting effect on the superhydrophobic microstructure. λ It should be a smaller value; at this point, the water droplet wets the lotus-shaped structure 1 and the pit 3, so the ratio of the actual wetted area of ​​the microstructure to the apparent geometric contact area is... f s1 It can be obtained from formula (5): , In the formula: f s1 It represents the ratio of the actual solid-wetting area of ​​a droplet to its apparent geometric contact area; λ The wetting coefficient is represented by . Substituting formulas (4) and (5) into formula (1), the numerical relationship between the designed superhydrophobic microstructure characteristics and the superhydrophobic function, i.e., the water droplet contact angle, can be obtained, as shown below: , In the formula: θ T and θ c These represent the theoretical and intrinsic contact angles, respectively. The intrinsic contact angle of a water droplet on a smooth surface is typically 100°–110°. In this embodiment, we take... θ c =104°; (3) Substitute the microstructure characteristic parameters into the numerical equation to calculate the theoretical value of the contact angle, and clarify the superhydrophobic microstructure characteristic parameters corresponding to a contact angle greater than 150°; in the embodiment, the composite microstructure characteristic parameters are: pit radius R t Designed to be 45 μm, Lotus seedpod-shaped structure bottom radius R fb Designed with a top radius of 35 μm for the lotus-shaped structure. R ft Designed to be 10 μm, The lotus-shaped structure has a concave top. R p Designed to have a pit radius of 8 μm. R Designed to be 20 μm; microstructure spacing D The design is 100μm.

[0023] 3. Select titanium alloy Ti6Al4V for surface polishing to achieve a surface roughness of 0.8 μm. Then clean and place it in a constant temperature oven at 40℃ for 30 min to dry the polished Ti6Al4V surface. Specifically, this includes: (1) Select Ti6Al4V titanium alloy as the matrix material for superhydrophobic microstructure and cut it into square samples of 2 cm × 2 cm. (2) Polish the surface of the Ti6Al4V sample to obtain a smooth surface with a roughness of 0.8 μm; (3) The polished Ti6Al4V sample was ultrasonically cleaned in anhydrous ethanol for 3 min, and then placed in a constant temperature oven and dried at 40℃ for 30 min to remove the impurities and moisture remaining on the sample surface.

[0024] 4. Femtosecond laser etching was performed on the polished and dried Ti6Al4V surface to prepare a composite microstructure consisting of a periodically arranged lotus-shaped structure and pits, specifically including: (1) Place the polished and dried Ti6Al4V sample on the femtosecond laser system platform, adjust the laser focus to the sample surface, and determine the laser scanning path based on the superhydrophobic microstructure characteristic parameters determined in step 2. (2) Set the femtosecond laser processing parameters: laser power 3 W, beam radius 10 μm, pulse duration 600 fs, laser wavelength 515 nm, laser frequency 300 KHz; (3) The lotus-shaped structure and pit structure are processed by multiple etchings on the sample surface by femtosecond laser.

[0025] 5. Using a high-purity TiO2 target (purity ≥ 99.9%), the distance between the target and the sample is controlled at 5–8 cm. A 50 nm TiO2 coating is deposited on the laser-etched Ti6Al4V surface using magnetron sputtering to obtain a Ti6Al4V superhydrophobic surface, specifically including: (1) Select high-purity TiO2 target material (purity ≥ 99.9%), and control the distance between the target material and the sample at 5–8 cm to ensure the uniformity of the coating. (2) Magnetron sputtering deposition was performed on the surface of the laser-etched Ti6Al4V sample. The stage rotation speed was set to 5 r / min to ensure the uniformity of the coating. After 2 h of deposition, a TiO2 coating with a thickness of 50 nm was obtained, and the Ti6Al4V superhydrophobic surface was finally obtained. The process is as follows: Figure 3 As shown.

[0026] To verify the superiority and feasibility of the method for designing and preparing a superhydrophobic microstructure on a lotus-shaped titanium alloy surface according to the present invention, the wettability of the superhydrophobic surface was characterized by multiple measurements to obtain the contact angle of water droplets on the superhydrophobic surface; the morphology and structure of the superhydrophobic surface were obtained, specifically including: (1) The superhydrophobic surface morphology of the titanium alloy was characterized by scanning electron microscopy (SEM, SU 8600, Carl Zeiss AG, Germany), such as... Figure 4 As shown; by Figure 4 As can be seen, the superhydrophobic microstructure obtained by femtosecond laser etching and magnetron sputtering deposition can be clearly seen under scanning electron microscope images at different magnifications; (2) The morphology and droplet state of the prepared superhydrophobic surface were characterized using a macro camera, such as... Figure 5 As shown; by Figure 5 It can be seen that the droplets exhibit a near-perfect spherical shape on the prepared titanium alloy superhydrophobic surface; (3) The contact angle of the Ti6Al4V superhydrophobic surface droplet was measured using a contact angle meter (SL-200KS, Solon Corporation, USA). Figure 6 As shown.

[0027] The specific testing method is as follows: the contact angle of water droplets on the superhydrophobic surface is measured using a contact angle meter; the superhydrophobic sample is placed on the measurement platform, and 5 μL of water droplets are dropped onto the superhydrophobic surface. The test results show that the contact angle is 154.62±2.31°, which is no different from the contact angle calculated by the numerical equation.

Claims

1. A method for designing and fabricating a superhydrophobic microstructure on the surface of a lotus-shaped titanium alloy, characterized in that... The design steps include the following: Step 1: Design the microstructure of the superhydrophobic surface, which consists of periodically arranged lotus seedpod-shaped structures and pit structures; Step 2: Based on the droplet wetting model, derive the mathematical equations and establish the numerical relationship between the structural characteristic parameters of the lotus-shaped structure and the pit and the superhydrophobic function, i.e., the water droplet contact angle. ， In the formula: θ T and θ c These represent the theoretical contact angle and the intrinsic contact angle, respectively. The intrinsic contact angle of a water droplet on a smooth surface is... θ c The angle is 100° to 110°. R t , R fb , R ft , R p , R These are the radius of the deep pit, the bottom radius of the lotus-shaped structure, the top radius of the lotus-shaped structure, the top recess of the lotus-shaped structure, and the radius of the recess. D The spacing of the microstructure; λ The wetting coefficient is the degree to which a water droplet wets a microstructure. It is the coefficient of water droplet concentration when the droplet floats on top of the microstructure. λ =0, when the water droplet completely wets the microstructure λ =1; The original numerical equations were used to determine the microstructure characteristic parameters corresponding to a water droplet contact angle greater than 150°, thus completing the design of the superhydrophobic microstructure. Step 3: Select titanium alloy Ti6Al4V for surface polishing treatment to achieve a surface roughness of 0.8 μm. Then clean it and place it in a constant temperature oven at 40℃ for 30 min to dry the polished Ti6Al4V surface. Step 4: The polished and dried Ti6Al4V surface is subjected to femtosecond laser etching to prepare a composite microstructure composed of periodically arranged lotus seedpod-shaped structures and pits. Step 5: Select a high-purity TiO2 target (purity ≥ 99.9%), control the distance between the target and the sample to 5–8 cm, and use magnetron sputtering to deposit a 50 nm TiO2 coating on the laser-etched Ti6Al4V surface to obtain a Ti6Al4V superhydrophobic surface.

2. The method for designing and preparing a superhydrophobic microstructure on the surface of a lotus-shaped titanium alloy according to claim 1, characterized in that... The microstructure consists of periodically arranged lotus seedpod-shaped structures and pitted structures. When droplets wet the superhydrophobic microstructure, the lotus seedpod-shaped structures and pitted structures can effectively trap air, forming an air film layer to achieve superhydrophobic function, while simultaneously achieving antibacterial and anti-adhesion through physical isolation.

3. The method for designing and preparing a superhydrophobic microstructure on the surface of a lotus-shaped titanium alloy according to claim 1, characterized in that, Step 2 specifically includes: (1) The designed lotus-shaped structure and pit structure have micron-level structural characteristic parameters, among which the radius of the deep pit is... R t Designed with a base radius of 40-50 μm in a lotus-shaped structure. R fb Designed with a top radius of 30-40 μm for the lotus-shaped structure. R ft Designed to be 10-15μm, with a lotus-shaped structure and a concave top. R p Designed to have a pit radius of 5-10 μm. R Designed to be 15-20 μm; microstructure spacing D Designed for 90-110 μm; (2) Substitute the structural characteristic parameters of the lotus seed pod structure and the pit structure into the mathematical equation to calculate the theoretical value of the water droplet contact angle. Determine whether it has superhydrophobic function based on whether the contact angle is greater than 150°, realize the controllable design of superhydrophobic surface, and clarify the characteristic parameters of superhydrophobic microstructure.

4. The method for designing and preparing a superhydrophobic microstructure on the surface of a lotus-shaped titanium alloy according to claim 1, characterized in that, Step 3 specifically includes: (1) Select Ti6Al4V titanium alloy as the matrix material for superhydrophobic microstructure and cut it into square samples of 2 cm × 2 cm. (2) Polish the surface of the Ti6Al4V sample to obtain a smooth surface with a roughness of 0.8 μm; (3) The polished Ti6Al4V sample was ultrasonically cleaned in anhydrous ethanol for 3 min, and then placed in a constant temperature oven and dried at 40℃ for 30 min to remove the impurities and moisture remaining on the sample surface.

5. The method for designing and preparing a superhydrophobic microstructure on the surface of a lotus-shaped titanium alloy according to claim 1, characterized in that, Step 4 specifically includes: (1) Place the polished and dried Ti6Al4V sample on the femtosecond laser system platform, adjust the laser focus to the sample surface, and determine the laser scanning path based on the superhydrophobic microstructure characteristic parameters determined in step 2. (2) Set the femtosecond laser processing parameters: laser power 3 KW, beam radius 10 μm, pulse duration 600 fs, laser wavelength 515 nm, laser frequency 300 KHz; (3) The lotus-shaped structure and pit structure are processed by multiple etchings on the sample surface by femtosecond laser.

6. The method for designing and preparing a superhydrophobic microstructure on the surface of a lotus-shaped titanium alloy according to claim 1, characterized in that, Step 5 specifically includes: (1) Select high-purity TiO2 target material (purity ≥ 99.9%), and control the distance between the target material and the sample at 5–8 cm to ensure the uniformity of the coating. (2) Magnetron sputtering deposition was performed on the surface of the Ti6Al4V sample after laser etching. The stage speed was set to 5r / min to ensure the uniformity of the coating. After 2 hours of deposition, a TiO2 coating with a thickness of 50 nm was obtained, and finally the Ti6Al4V superhydrophobic surface was obtained.

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