Near-atomic-scale electrolytic machining method based on interface self-assembly biomask

Abstract

A near-atomic-scale electrolytic machining method based on an interface self-assembly biomask comprises the steps that firstly, hydroxylation pretreatment is conducted on the surface of an anode of a workpiece, then the surface of the anode is covered with an organic solvent phase containing phospholipid monomers, water-phase electrolyte drops are introduced, molecular self-assembly driving force at an oil-water-metal three-phase interface is utilized, and the surface of the anode of the workpiece is subjected to near-atomic-scale electrochemical machining. And rapidly forming a layer of ultrathin, continuous and stable support phospholipid bilayer mask on the surface of the workpiece in situ. Then, biological nanochannels are embedded in the biomimetic mask to construct a confinement ion transport path. And finally, a precise pulse electric field is applied, electrolyte ions are driven to be strictly limited in the nanometer channel and transmitted to the surface of the workpiece, local anodic dissolution is triggered, and therefore localized material removal of the nanometer scale or even the near-atomic scale is achieved. According to the method, the technical bottleneck that the high-quality phospholipid bilayer is difficult to prepare on the high-surface-energy metal surface is solved, and a new way is provided for ultra-precision electrolytic machining.

Description

Technical Field

[0001] This invention relates to the field of electrochemical machining, and more particularly to a near-atomic-scale electrochemical machining method based on an interface self-assembled biomass mask. Technical Background

[0002] Supported phospholipid bilayers, as the basic framework of cell membranes, are considered ideal masking materials for near-atomic-scale electrochemical machining due to their inherent molecular-level thickness (approximately 5 nanometers), excellent self-sealing properties, and natural compatibility with biological ion channel proteins. Their core function is to act as an ultrathin, insulating, dynamic barrier, confining electrochemical reactions to the nanometer or even near-atomic scale. However, the practical application of this technology faces a fundamental challenge: how to efficiently and non-destructively prepare high-quality supported phospholipid bilayers on metal workpieces (especially high-surface-energy metals commonly used in electrochemical machining) that are unsuitable for traditional film-forming methods.

[0003] Currently, the classic methods for constructing supported phospholipid bilayers, such as vesicle fusion, solvent-assisted methods, and droplet contact methods, are highly dependent on the properties of the substrate. Numerous studies (e.g., Mingeot-Leclercq MP, Deleu M, Brasseau R, et al. Atomic force microscopy of supported lipid bilayers[J]. Nature Protocols, 2008, 3(10): 1654-1659.) have shown that vesicle fusion is effective on substrates such as mica, silica, silicon nitride, and low-surface-energy metals like gold. However, for high-surface-energy metal workpieces such as Fe, Ni, Cr, Ti, Al, and their alloys, which are widely used in electrochemical machining, the extremely high interfacial energy barrier makes it difficult for vesicles to effectively rupture and spread into a uniform and continuous phospholipid bilayer. Even with the addition of Mg to the vesicle solution… 2+ Ca 2+ Buffers that promote vesicle rupture often have little effect on high surface energy metals, failing to achieve complete or uniform rupture and spread. The core idea of ​​Chinese inventions CN102749239A and CN105448698B is also based on the vesicle fusion method to construct phospholipid films on specific support substrates (such as indium tin oxide conductive glass), but it has failed to solve the film formation problem of high surface energy metal workpieces.

[0004] On the other hand, solvent-assisted methods require a flowing electrolyte environment, which introduces uncontrollable factors for near-atomic scale processing that seeks localized precision, and is obviously disadvantageous. Typical droplet contact methods (such as Leptihn S, Castell OK, Cronin B, et al. Constructing droplet interface bilayers from the contact of aqueous droplets in oil[J]. Nature Protocols, 2013, 8(6): 1048-1057.) are usually suitable for hydrogels or water-rich substrates, and cannot be directly transferred to metal surfaces to achieve reliable support bilayers.

[0005] In addition, although Chinese invention CN113321815A explored the construction of a stable phospholipid layer on the surface of MOF materials through chemical grafting, this method forms a self-assembled monolayer by n-octadecyl phosphate and combines it with lecithin and other substances. However, this process takes as long as 24-28 hours and introduces heterogeneous chemical components (such as cholesterol as a stabilizer). Its complex interfacial chemistry may cause unpredictable interference to the subsequent electrochemical processing environment, making it difficult to meet the requirements of efficient and pure processing.

[0006] Essentially, the self-assembly behavior of phospholipid molecules at interfaces is heavily regulated by interfacial energy and hydration. Studies have shown (e.g., Ferhan AR, Yoon BK, Park S, et al. Solvent-assisted preparation of supported lipid bilayers[J]. Nature Protocols, 2019, 14(7): 2091-2118.) that amphiphilic phospholipid molecules can spontaneously assemble under interfacial tension by creating a suitable interfacial hydration environment. Hydroxylation of metal surfaces is a key approach to regulating their surface properties, enhancing water molecule adsorption, and thus creating favorable conditions for film formation. The hydroxyl groups (-OH) on metal surfaces can not only change the interfacial energy but also provide a "template" for the orderly assembly of phospholipid molecules through specific interactions with the metal.

[0007] Therefore, based on self-assembly theory, the principle of energy minimization, and surface hydroxyl chemistry, an innovative strategy is proposed to overcome the long-standing challenge of non-destructive and rapid spreading of phospholipid bilayers on high surface energy metal workpieces. This method focuses on constructing ideal interfaces for the subsequent functional embedding of ion channel proteins, which is an indispensable prerequisite and key step for realizing truly near-atomic scale electrochemical machining. Summary of the Invention

[0008] Technical Problem Solved: Addressing the technical challenges of efficiently and non-destructively constructing support phospholipid bilayer masks suitable for near-atomic-scale electrochemical machining on high-surface-energy metal workpieces in existing technologies—such as the high interfacial energy barrier and uneven spreading issues in vesicle fusion methods, the uncertainty introduced by solvent-assisted methods due to their reliance on the flow environment, the limitations of droplet contact methods on substrate materials, and the excessive time consumption and potential interface contamination in chemical grafting methods—this invention provides a near-atomic-scale electrochemical machining method based on interface self-assembly of biomasses. This method establishes a universal approach for the in-situ, rapid, and gentle formation of high-quality, ultrathin, continuous, and stable support phospholipid bilayer masks on widely used high-surface-energy metal workpieces such as Fe, Ni, Cr, Ti, Al, and their alloys. This method overcomes the film-forming barriers caused by high interfacial energy, avoids lengthy and complex chemical processes or harsh environmental conditions, and ensures a pure and non-destructive mask-workpiece interface. This lays a crucial foundation for subsequent integration of biological nanochannels and the realization of precise and reliable near-atomic-scale electrochemical machining.

[0009] Technical Solution: A near-atomic-scale electrochemical machining method based on an interface self-assembly biomass mask, comprising: S1. In-situ formation of the interface self-assembly mask: covering the anode surface of a workpiece pretreated with hydroxylation with an organic solvent phase containing phospholipid monomers; introducing aqueous electrolyte droplets into the organic solvent phase to form a three-phase interface between the aqueous electrolyte droplets, the organic solvent phase, and the anode surface of the workpiece; utilizing the molecular self-assembly driving force at the three-phase interface to form a supporting phospholipid bilayer as a dynamic mask in situ on the anode surface of the workpiece; S2. Integration of nano-ion channels: embedding bio-nanochannels into the supporting phospholipid bilayer to form confined ion transport pathways; S3. Confined electrochemical machining: using the workpiece anode integrated with the bio-nanochannels as an electrode, applying a pulsed electric field to drive electrolyte ions to be confined and transported to the workpiece surface through the bio-nanochannels, inducing localized anode dissolution and achieving near-atomic-scale localized material removal.

[0010] In step S1, the contact time between the aqueous electrolyte droplets and the anode surface of the workpiece in the organic solvent phase is controlled to promote the formation of a continuous and complete supporting phospholipid bilayer.

[0011] The above-mentioned organic solvent phase is prepared by dissolving phospholipid monomers in an organic solvent that is immiscible with the aqueous electrolyte; the organic solvent is selected from non-volatile organic solvents, and the non-volatile organic solvent is at least one of hexadecane, decane, tetradecane, squalene or silicone oil.

[0012] The concentration of the phospholipid monomers in the organic solvent phase is from 5 mg / mL to 50 mg / mL.

[0013] The above-mentioned hydroxylation pretreatment is achieved by plasma treatment or ultraviolet treatment; the plasma treatment uses a mixed gas containing easily hydroxylated gases and inert gases, and the hydroxyl density on the anode surface of the workpiece is controlled by adjusting the plasma power and treatment time.

[0014] The aforementioned bio-nanochannels are ion channel proteins, engineered polypeptide channels, or biomimetic nanopores constructed based on DNA origami.

[0015] In step S1, the successful formation of the mask is confirmed by monitoring the changes in membrane capacitance or impedance during the formation of the supporting phospholipid bilayer.

[0016] The above monitoring process was carried out in an electromagnetically shielded environment.

[0017] A near-atomic-scale electrochemical machining apparatus for implementing the method includes: an electrolytic cell containing a phospholipid-containing organic solution; a stage at the bottom of the electrolytic cell; a workpiece anode on the stage; a Faraday shield covering the workpiece anode; a pipette cathode passing through the Faraday shield and positioned above the workpiece anode; the pipette cathode and the workpiece anode being connected to an electrochemical workstation, which applies a pulsed electric field and monitors the electrical signal; the pipette cathode is used to controllably introduce droplets of electrolyte into the phospholipid-containing organic solution.

[0018] A workpiece whose surface is processed by the above method to form near-atomic scale feature structures.

[0019] Beneficial effects: 1. It overcomes the limitations of film formation on high surface energy metal substrates, broadening the application scope of the technology. Traditional methods such as vesicle fusion are only suitable for low surface energy substrates such as gold and mica, and cannot form complete and continuous phospholipid bilayers on high surface energy metal surfaces such as Fe, Ni, Cr, Ti, Al and their alloys commonly used in electrochemical machining. This invention, through ingenious interface design, effectively overcomes the high interface energy barrier, and for the first time achieves in-situ construction of high-quality biomimetic masks on the surfaces of these "difficult-to-process" metal workpieces. This expands the application scope of the near-atomic-scale confined dissolution electrochemical machining method of ion channel proteins from a limited number of model substrates to the vast majority of functional metal materials.

[0020] 2. This invention enables efficient and rapid construction of biomimetic masks, significantly improving process feasibility. Compared to existing film-forming processes that are time-consuming or require stringent conditions (such as solvent-assisted methods which require a flowing environment), the self-assembly principle-based method of this invention is simple and rapid. It requires no complex chemical modifications or multi-step reactions, and can complete non-destructive spreading on metal surfaces within minutes to tens of minutes, significantly improving the efficiency and controllability of the entire nanofabrication process, making it more suitable for practical manufacturing scenarios.

[0021] 3. This invention ensures the integrity and purity of the workpiece interface and mask, laying the foundation for atomic-level machining. The method of this invention does not rely on chemical grafting, strong fusion, or mechanical flow that may introduce contamination or damage. Instead, it guides phospholipid molecules to undergo gentle self-assembly by regulating the surface hydroxyl chemistry and interfacial energy. This not only avoids potential interference from heterogeneous molecules (such as cholesterol and grafting molecules in Chinese invention CN113321815A) on the subsequent electrochemical environment, but more importantly, it completely preserves the atomic-level flatness and chemical state of the metal workpiece surface, providing crucial original interfacial conditions for achieving truly near-atomic-scale precision machining.

[0022] 4. A high-quality, highly stable supporting phospholipid bilayer is formed, ensuring the localization and reliability of the processing. By optimizing the surface hydration and self-assembly processes, this invention can form a dense, continuous phospholipid bilayer with dynamic self-healing properties on the metal surface. The mask quality is comparable to that obtained by traditional methods on ideal substrates, effectively isolating non-reactive regions and thus strictly confining the electrochemical reaction within the pre-defined nanochannel region. This not only greatly improves the localization of the processing but also enhances the operational stability and repeatability of the entire processing system under complex environments.

[0023] 5. This invention provides a universally applicable and standardized process framework, lowering the technical threshold. The surface hydroxylation treatment and interface self-assembly principle upon which this invention relies have good universality for different types of metal materials. Compared to the current situation where different film-forming technologies need to be developed for different materials, this invention provides a relatively unified and standardized process path. This is conducive to the promotion and application of this technology, and reduces the technical threshold and R&D costs for achieving near-atomic scale electrolytic processing on various metal materials. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a biomass mask forming and processing method for near-atomic scale electrolytic processing.

[0025] Figure 2 This is a schematic diagram of the formation principle of the hydroxyl-modified layer and the self-assembled monolayer on its surface.

[0026] Figure 3 This is a schematic diagram of the formation of a self-assembled monolayer at the oil-water interface.

[0027] Figure 4 This is a waveform diagram of characteristic signal detection using a phospholipid bilayer mask.

[0028] Figure 5 This is a TEM image of a 1nm metal hole obtained through electrolytic processing.

[0029] Figure 6These are the IV curves of phospholipid bilayer masks characterized after different plasma treatments.

[0030] Figure 7 It is an XPS image of a workpiece with high hydroxyl coverage and high surface oxidation.

[0031] Figure 8 It is an XPS image of a workpiece with high hydroxyl coverage and low surface oxidation.

[0032] Figure 9 This is a comparison of the impedance of phospholipid bilayer masks under different organic solvent atmospheres.

[0033] Numbers and names in the figure: 1. Electrolytic cell; 2. Pipette cathode; 3. Electrochemical workstation; 3-1. Triangular wave; 3-2. Square wave; 4. Faraday shielding box; 5. Stage; 6. Electrolyte; 6-1. Electrolyte drop 1; 6-2. Oil-water interface; 6-3. Electrolyte drop 2; 6-4. Self-assembled monolayer 2; 6-5. Phospholipid bilayer mask; 7. Workpiece anode; 7-1. Nanoplasma / UV treatment; 7-2. Hydroxyl modification layer; 8. Phospholipid-containing organic solvent; 8-1. Phospholipid monomer; 8-2. Self-assembled monolayer 1. Detailed Implementation

[0034] This invention provides a biomask forming and processing method for near-atomic scale electrochemical machining. The core concept of this method is to mimic the natural formation process of biological cell membranes, and spontaneously construct an ultrathin phospholipid bilayer as a dynamic insulating mask on the pre-treated workpiece surface using the self-assembly principle of a three-phase interface (metal / organic solvent / aqueous solution). Subsequently, biomacromolecules (or their biomimetic structures) with precise nanopores are embedded in this biomimetic membrane, forming a unique ion transport pathway. Finally, by applying a precise pulsed electric field, electrolyte ions are driven to be strictly confined within this nanochannel and transported to the workpiece surface, initiating highly localized electrochemical anodic dissolution, thereby achieving near-atomic scale targeted material removal.

[0035] The technical solution specifically includes the following key steps:

[0036] 1. In-situ construction of biomimetic confined masks

[0037] This step aims to form a complete, dense, and stable insulating barrier on the anode surface of the workpiece. First, the anode surface is pretreated, for example, by forming a self-assembled monolayer (SAM), grafting a polymer brush, or undergoing plasma treatment, to modulate its hydrophilicity / hydrophobicity, charge, and functional groups, making it suitable for subsequent adsorption and self-assembly of phospholipid molecules. Then, a droplet-interface self-assembly technique is employed: an organic solvent phase containing dissolved phospholipid monomers (such as long-chain alkanes, silicone oil, or other water-insoluble solvents) is applied to the workpiece surface, followed by the introduction of a droplet of aqueous electrolyte. At the two-phase interface, phospholipid molecules spontaneously align under the drive of intermolecular forces, ultimately forming a transversely continuous supported phospholipid bilayer at the workpiece-organic solvent-aqueous solution three-phase interface. This process can optimize the film's smoothness and integrity by controlling the contact and interaction time of the aqueous droplet in the organic phase. The film formation quality can be assessed in situ by monitoring its characteristic electrical signals (such as film capacitance and impedance).

[0038] 2. Functional integration of nanoscale ion channels

[0039] In the formed phospholipid bilayer mask, functional units that provide ion transport pathways need to be integrated. This invention employs bio-nanochannels as these functional units, which can be natural ion channel proteins (such as α-hemolysin, MspA), engineered peptide channels, or biomimetic nanopores constructed based on DNA origami techniques. These biomolecules are directionally embedded in the membrane through the interaction of their hydrophobic regions with the hydrophobic core of the phospholipid bilayer. The internal channels (typically 0.1-20 nm in size) become the sole electrolyte channels for penetrating the insulating mask, directly defining the lower limit of the size of the subsequent electrochemical reaction region.

[0040] 3. Pulsed electric field-driven confined electrochemical dissolution

[0041] Using the constructed "workpiece-biomimetic mask-nanochannel" composite structure as the workpiece anode, the workpiece is placed in an electrolyte and a precise pulsed electric field is applied. The parameters of this pulsed electric field (such as amplitude, pulse width, and frequency) are specifically designed. During the pulse conduction period (processing phase), the electric field drives reactive ions (such as OH⁻) in the electrolyte to be rapidly and confined through the bio-nanochannel to a tiny region (nanoscale) on the workpiece surface directly below the channel, initiating selective anodic dissolution of metal atoms at that location. During the pulse interval (diffusion / removal phase), reaction products diffuse out, preventing channel blockage. By controlling the pulse sequence, atomic-level regulation of the material removal rate and precision can be achieved.

[0042] 4. Parallel processing and process monitoring

[0043] To achieve high-efficiency processing, an array of masks containing multiple bio-nanochannels can be constructed on the surface of the same workpiece. Through global electric field control, large-scale parallel near-atomic scale processing can be achieved. The entire mask formation and processing process can be carried out in an electromagnetically shielded environment to isolate the interference of environmental noise on weak electrical signals (such as pA-level ion currents) and ensure the reliability of process monitoring and control.

[0044] The specific options available are as follows:

[0045] Workpiece pretreatment steps: Select metal workpieces, first perform degreasing, water washing, and drying, then treat the surface with argon-oxygen mixed gas (volume ratio 90:10) plasma to form a hydrophilic modification layer to enhance the bonding force of the phospholipid bilayer. If the workpiece surface roughness (Ra) is greater than 1 nm, it may lead to incomplete phospholipid bilayer coverage and leakage points. Atomic force microscopy (AFM) is used to check the surface smoothness to ensure Ra ≤ 0.5 nm; workpieces that do not meet the standard are subjected to mechanical-chemical polishing.

[0046] Biomimetic confined interface construction: Dioleoylphosphatidylcholine (DOPC) phospholipid monomer (concentration 10 mg / mL) was pre-dissolved in pentane. The pentane was evaporated in a vacuum environment, and a white, transparent phospholipid bilayer dry film could be seen on the side wall of the solvent bottle. Then, the phospholipid bilayer was redissolved in hexadecane to a final volume of 10 mg / mL. Phosphate buffer (electrolyte) at pH 7.4 was taken in a pipette, and the workpiece was immersed in the hexadecane containing phospholipid monomer organic solvent for 3-5 minutes. Phospholipid monolayers formed at the workpiece surface-organic solvent interface through self-assembly. Another monolayer formed at the organic solvent-electrolyte droplet interface. The pipette was moved until the two monolayers came close together, thus forming a phospholipid bilayer mask. Subsequently, 100 ng / mL of α-hemolysin ion channel protein (inner diameter approximately 1.4 nm) was added to the electrolyte, and the protein was embedded into the mask using hydrophobic interactions. Before adding α-hemolysin ion channel protein, the change in current under constant voltage was tested. If the current was infinitely close to 0 pA, the phospholipid bilayer insulating mask was well formed, and the next step could be performed. Simultaneously, the phospholipid bilayer insulating mask was subjected to UV-induced cross-linking treatment at a power of 20 W, a wavelength of 254 nm, a treatment time of 3 minutes, and an irradiation distance of 2 cm to enhance stability and breakdown voltage.

[0047] Electrolytic machining process: The tool cathode is a platinum wire with a needle tip radius of 5 μm. The distance between the workpiece anode and the tool cathode is adjusted to 10 μm. A pulsed electric field (parameters: pulse width 200 ps, ​​interval 500 ps, ​​amplitude 50 mV) is applied to drive the anions and cations through the protein channels and cause an electrochemical reaction at the workpiece anode interface.

[0048] Example 1

[0049] Combined with appendix Figure 1-5 Please provide an explanation.

[0050] A near-atomic-scale electrochemical machining apparatus for implementing the method includes an electrolytic cell 1 containing a phospholipid-containing organic solution 8. A stage 5 is provided at the bottom of the electrolytic cell, and a workpiece anode 7 is provided on the stage 5. A Faraday shielding box is provided over the workpiece anode 7. A pipette cathode 2 passes through the Faraday shielding box 4 and is positioned above the workpiece anode 7. The pipette cathode 2 and the workpiece anode 7 are respectively connected to an electrochemical workstation 3, which applies a pulsed electric field and monitors the electrical signal. The pipette cathode 2 is used to controllably introduce droplets of electrolyte 6 into the phospholipid-containing organic solution 8.

[0051] S1: Using magnetron sputtered Cr as the spreading mask, the degreased and dried atomically flat Cr workpiece anode 7 is subjected to nano-plasma / UV treatment 7-1. The plasma power, oxygen content (10%), argon content (90%), flow rate (30 sccm), and treatment time (30 s) are set. The core challenge lies in how to avoid oxidation of the hydroxyl surface of the workpiece, as oxygen is a precursor to hydroxyl formation. After treatment, a dense hydroxyl modification layer 7-2 is formed on the surface of the Cr workpiece anode 7. Immediately after modification, the Cr workpiece anode 7 is transferred and fixed onto the stage 5 at the bottom of the electrolytic cell 1, or stored in ethanol for later use. Do not allow it to come into contact with N,N dimethylformamide to prevent damage to the hydroxyl groups.

[0052] S2: Install and debug the Faraday shield box 4, and adjust the height of the quartz pipette cathode 2 with a port diameter of micrometers pulled by the carbon dioxide laser puller relative to the surface of the Cr workpiece anode 7 to a reasonable position; dissolve 10 mg of DPhPC in 1 mL of chloroform, dry it under mild nitrogen, and place it in a vacuum environment to dry for 2 hours. Then, redissolve DPhPC in 0.5 mL of hexadecane and 0.5 mL of silicone oil. The concentration of the phospholipid-containing organic solution 8 (hexadecane / silicone oil organic solvent containing DPhPC phospholipids) is 10 mg / mL, and inject it into the electrolytic cell 1 so that the phospholipid-containing DPhPC hexadecane / silicone oil organic solvent is submerged to a reasonable position. The positive and negative electrodes of the electrochemical workstation 3 are connected to the Cr workpiece anode 7 and the quartz pipette cathode 2, respectively.

[0053] S3: DPhPC phospholipid monomer 8-1 in phospholipid-containing hexadecane / silicone oil organic solvent 8 self-assembles on hydroxyl-modified layer 7-2 to form self-assembled monolayer 1 8-2.

[0054] S4: Starting from step S3, NaCl electrolyte 6 is extruded from the cathode 2 of the quartz pipette. The electrolyte 6 initially forms electrolyte droplets 1 6-1. At this time, DPhPC phospholipid monomer 8-1 begins to self-assemble at the oil-water interface 6-2 between the phospholipid DPhPC hexadecane / silicone oil organic solvent 8 and the NaCl electrolyte droplets 1 6-1. After waiting for 10 minutes, the NaCl electrolyte droplets 1 6-1 change their form to NaCl electrolyte droplets 2 6-3 due to the decrease in surface tension. At this time, the DPhPC phospholipid monomer 8-1 completes the self-assembly of self-assembled monolayer 2 6-4 at the oil-water interface 6-2.

[0055] S5: Drive the quartz pipette cathode 2 downwards until the self-assembled monolayer 2 6-4 contacts the self-assembled monolayer 1 8-2. At the same time, start the electrochemical workstation 3 (model: PARSTAT 4000A, USA), input a 50Hz triangular wave voltage signal with an amplitude of 150mV, and record the output current signal. If the current signal is a square wave current signal with the same frequency and an amplitude of 50pA, stop moving the quartz pipette cathode 2. At this time, the phospholipid bilayer 6-5 is formed.

[0056] S6: If no square wave 3-2 current signal with the same frequency and amplitude of 50pA appears, repeat steps S3, S4 and S5 above. When a square wave 3-2 current signal appears, stop all operations and wait for subsequent ion channel protein insertion and electrolytic processing.

[0057] S7: After completing the inspection in step S6, using a platinum wire as the tool cathode with a needle tip radius of 5 μm, adjust the distance between the workpiece anode and the tool cathode to 10 μm. Apply a pulsed electric field (parameters: pulse width 200 ps, ​​interval 500 ps, ​​amplitude 50 mV) to drive the anions and cations through the protein channels, causing an electrochemical reaction at the workpiece anode interface. The processing results are as follows. Figure 5 As shown, electrolytic nanopores of about 1 nm are visible.

[0058] Example 2

[0059] This embodiment systematically studies the key influence of workpiece surface hydroxylation modification on phospholipid self-assembly. By adjusting pretreatment parameters (plasma atmosphere, time, and power), precise control of hydroxyl density and distribution is achieved to improve film quality. Nickel, commonly used in electrolytic machining, is used as the workpiece anode 7, and its surface is mechanically polished to atomic-level flatness (Ra < 0.5 nm). Subsequently, hydroxylation modification is performed. The workpiece is placed in a low-temperature plasma treatment device, and a mixed gas (O2:Ar volume ratio = 1:4, total flow rate 50 sccm) is introduced. The plasma power (30W) and treatment time (1-3 minutes) are adjusted accordingly. Figure 6The It curves (voltage = 100mV) after the formation of the phospholipid bilayer mask are shown under processing times of 1 min, 2 min, and 3 min. The phospholipid bilayer mask with the best quality was obtained after 1 min of processing, with a current of 2 pA. Under processing times greater than 2 min, the phospholipid bilayer mask quality was poor, incompletely formed, and lacked effective shielding of the non-electrolytic processing area; the current was between 60-70 pA. This is related to the excessive physical bombardment of Ar and excessive oxidation of O2 during plasma processing, leading to a significant increase in surface roughness. This was also confirmed by XPS detection of the O1s characteristic binding energy, such as... Figure 7 As shown, excessive plasma treatment results in a higher 529 eV binding energy intensity, while shorter plasma treatment times do not produce such a strong characteristic peak in O1s (e.g., Figure 8 The 529 eV binding energy site often represents the formation of oxides; in this example, it represents the formation of chromium oxide, indicating that the 2-min and 3-min plasma treatments led to excessive oxide formation and the generation of non-functional oxides (hydroxyl groups). The workpiece was immediately transferred to electrolytic cell 1 after treatment to prevent degradation of the hydroxyl layer (avoiding contact with solvents such as DMF). DPhPC phospholipid monomer 8-1 was dissolved at a fixed concentration of 10 mg / mL in a hexadecane / silicone oil (1:1 volume ratio) mixed solvent. The aqueous electrolyte 6 was a 0.1 M NaCl solution, injected as droplets through the cathode 2 via a pipette.

[0060] Example 3

[0061] This embodiment explores the effects of different organic solvents (hexadecane and squalene) on the solubility of phospholipid monomers, interfacial self-assembly kinetics, and mask stability, aiming to establish a standard procedure for solvent selection. Specific steps: S1: Standardized workpiece pretreatment. Using a nickel (Ni) workpiece anode 7 as the substrate, a hydroxyl-modified layer 7-2 was formed under the high hydroxyl density conditions of Example 1 (plasma power 30 W, time 1 minute) to eliminate surface variable interference. S2: Comparative design of organic solvent systems. Two organic solvent phases were prepared, both dissolving DPhPC phospholipids (concentration 10 mg / mL): Solvent A (long-chain alkane): hexadecane (low polarity, beneficial for the dispersion of hydrophobic tails of phospholipids). Solvent B (squalene): high viscosity, delaying interfacial diffusion and improving self-assembly order. Each solvent was injected separately into electrolytic cell 1, covering the workpiece surface. The stability of the phospholipid bilayer was summarized through impedance testing. Figure 9As shown, due to the difference in surface tension between squalene and hexadecane, the phospholipid bilayer formed by this method inevitably leaves organic solvent residue in the intermediate hydrophobic water area. This solvent expands during subsequent electrical pulses, damaging the mask structure. For example, the phospholipid-containing organic solvent formed by squalene can be rapidly discharged from the hydrophobic water area after mask formation, while hexadecane has difficulty achieving a similar effect. This explains the significant difference in impedance between the phospholipid bilayer masks formed by the two. In this embodiment and subsequent experiments, squalene organic solvent is preferred.

Claims

1. A near-atomic-scale electrochemical machining method based on an interface self-assembly biomass mask, characterized in that, The method includes: S1. In-situ self-assembly mask forming step: covering the hydroxylated pretreated workpiece anode surface with an organic solvent phase containing phospholipid monomers; introducing aqueous electrolyte droplets into the organic solvent phase to form a three-phase interface between the aqueous electrolyte droplets, the organic solvent phase, and the workpiece anode surface; utilizing the molecular self-assembly driving force at the three-phase interface, forming a supporting phospholipid bilayer in situ on the workpiece anode surface as a dynamic mask; S2. Nanochannel integration step: embedding bio-nanochannels into the supporting phospholipid bilayer to form confined ion transport pathways; S3. Confined electrochemical processing step: using the workpiece anode integrated with the bio-nanochannels as an electrode, applying a pulsed electric field to drive electrolyte ions to be confined and transported to the workpiece surface through the bio-nanochannels, initiating localized anode dissolution and achieving near-atomic scale localized material removal.

2. The method according to claim 1, characterized in that, In step S1, the contact time between the aqueous electrolyte droplets and the anode surface of the workpiece in the organic solvent phase is controlled to promote the formation of a continuous and complete supporting phospholipid bilayer.

3. The method according to claim 1, characterized in that, The organic solvent phase is prepared by dissolving phospholipid monomers in an organic solvent that is immiscible with the aqueous electrolyte; the organic solvent is selected from non-volatile organic solvents, and the non-volatile organic solvent is at least one of hexadecane, decane, tetradecane, squalene or silicone oil.

4. The method according to claim 3, characterized in that, The concentration of the phospholipid monomer in the organic solvent phase is from 5 mg / mL to 50 mg / mL.

5. The method according to claim 1, characterized in that, The hydroxylation pretreatment is achieved through plasma treatment or ultraviolet treatment; the plasma treatment uses a mixed gas containing easily hydroxylated gases and inert gases, and the hydroxyl density on the anode surface of the workpiece is controlled by adjusting the plasma power and treatment time.

6. The method according to claim 1, characterized in that, The bio-nanochannels are ion channel proteins, engineered polypeptide channels, or biomimetic nanopores constructed based on DNA origami.

7. The method according to claim 1, characterized in that, In step S1, the successful formation of the mask is confirmed by monitoring the changes in membrane capacitance or impedance during the formation of the supporting phospholipid bilayer.

8. The method according to claim 7, characterized in that, The monitoring process is conducted in an electromagnetically shielded environment.

9. A near-atomic-scale electrochemical machining apparatus for carrying out the method according to any one of claims 1-8, characterized in that, include: An electrolytic cell (1) is filled with a phospholipid-containing organic solution (8). A stage (5) is provided at the bottom of the electrolytic cell. A workpiece anode (7) is provided on the stage (5). A Faraday shield is provided on the workpiece anode (7). A pipette cathode (2) passes through the Faraday shield (4) and is located above the workpiece anode (7). The pipette cathode (2) and the workpiece anode (7) are respectively connected to an electrochemical workstation (3). The electrochemical workstation (3) applies a pulsed electric field and monitors the electrical signal. The pipette cathode (2) is used to controllably introduce droplets of electrolyte (6) into the phospholipid-containing organic solution (8).

10. A workpiece, characterized in that, Its surface is processed by the method described in any one of claims 1-8 to form a near-atomic scale feature structure.

Images