Preparation method of flexible array microprobe

Abstract

The invention discloses a preparation method of a flexible array microprobe in the field of semiconductors and microelectronics, which comprises the following steps: S1, providing a quartz glass substrate, carrying out organic cleaning treatment, carrying out acetone-isopropanol-deionized water three-step ultrasonic cleaning with the ultrasonic power of 50-200W and the time of 5-15 minutes, and drying in a vacuum oven at 80 DEG C for 30 minutes after cleaning; and S2, preparing an ultraviolet narrow-band filter film on the quartz glass substrate, wherein the filter film adopts an HfO2 / SiO2 alternating film layer structure. The ultraviolet narrow-band optical filter is designed for an exposure light source of a wide-spectrum photoetching machine (the spectrum range of a mercury lamp is 300-600 nm), specific wavelength selective transmission is achieved, the diffraction light field definition is improved through the narrow-band optical filter, and the smoothness of the side wall of the microneedle is improved; in addition, complex mask exposure equipment or gray mask plate preparation is not needed, through the ultraviolet narrow-band filter design and the diffraction light field regulation and control technology, the technological process is simplified, the geometric accuracy of the microneedle is improved, and the technological cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors and microelectronics, and specifically to a preparation method of a flexible array microprobe. Background Art

[0002] In recent years, flexible array microprobes have been widely used in fields such as biomedicine (such as drug delivery, skin puncture, etc.) and sensors (such as flexible electronic tactile sensors, biosensors, etc.). Currently, the mainstream processing technology of array microprobes includes various micro-nano processing technology methods such as the microtemplate method (casting method, hot embossing method, injection molding method), 3D printing method, MEMS microfabrication process method, laser ablation method, and LIGA process method.

[0003] The micro - template method is a commonly used method for preparing polymer - array microneedles, mainly including the casting method, hot embossing method, and injection molding method. These methods use micro - templates to precisely control the geometry of microneedles. Among them, polydimethylsiloxane (PDMS) has become the most commonly used template material due to its flexibility and non - adhesion to polymer materials. The casting method involves casting a mixed solution of drugs and polymers onto an array microneedle mold, and filling the solution by means of centrifugation, vacuum pumping, or ultrasonic waves. After drying, polymer - array microneedles are obtained. However, the casting method may have problems such as incomplete solution filling, resulting in incomplete microneedle structures, and the drying process may take a long time. The hot embossing method heats the polymer material to a certain temperature to fully fill it into the mold, and demolds after cooling and curing. However, the hot embossing method has high requirements for temperature control. If the temperature is not appropriate, it may cause changes in the properties of the polymer material or failure to fill the mold well, and the demolding process may damage the microneedle structure. The injection molding method uses an injection molding machine to pressurize the molten polymer to fill it into the mold, and forms microneedles after cooling. However, the injection molding method requires high - precision injection equipment with high equipment costs, and improper control of the injection pressure may cause deviations in the shape of microneedles. 3D printing technology can manufacture microneedles with complex geometries. This method realizes the customization of microneedles by layer - by - layer deposition of materials, and is suitable for manufacturing microneedles with features such as drug reservoirs or drug delivery channels. Although 3D printing technology allows the customization of microneedle geometries, it currently faces limitations in resolution and speed. The precision of the printed microneedles may not meet the requirements of some high - precision application scenarios, and the printing speed is relatively slow, making it not suitable for large - scale production. In addition, some materials may not be suitable for biomedical applications, limiting its wide application in the biomedical field, and 3D printing equipment is usually expensive with high maintenance costs. The MEMS micro - processing technology is widely used in the manufacture of microneedle arrays. This technology can provide high - precision patterning and is suitable for manufacturing complex microneedle arrays. By using a photomask to pattern a polymer film and then etching to create a microneedle array, lithography technology can achieve precise control of the microneedle geometry. Combining dry and wet etching technologies can prepare microneedle arrays with high aspect ratios. Through the sacrificial layer technology, the tips of microneedles can be sharpened during the etching process, thereby improving the strength and performance of microneedles. However, the lithography process may be time - consuming and requires expensive equipment, with a complex operation process and high technical requirements for operators. Dry etching usually needs to be carried out in a vacuum environment, with complex equipment, high costs, and great operation difficulty. Wet etching may have problems such as side - wall inclination caused by isotropic etching, affecting the geometric accuracy of microneedles. The etching solution is corrosive to a certain extent, and the etching time and etching conditions need to be strictly controlled. Otherwise, over - etching or under - etching may occur, and at the same time, the etching waste liquid needs to be properly treated to avoid environmental pollution. The laser ablation technology forms a microneedle structure by focusing a laser beam on the material surface, causing local melting and vaporization.This method can precisely control the geometry of the microneedles and is suitable for manufacturing microneedles with a high aspect ratio. However, the laser ablation technique is also expensive and requires specialized equipment, and the acquisition and maintenance costs of the equipment are relatively high. Moreover, the laser ablation process may cause thermal damage to the material, affecting the performance and quality of the microneedles. Precise control of laser parameters is required during operation, otherwise processing defects are likely to occur, such as rough microneedle surfaces and irregular shapes. The LIGA technology method includes steps such as X-ray lithography, electroforming, and plastic casting. This method can manufacture microneedles with high strength and precise dimensions and is suitable for transdermal drug delivery systems. However, the LIGA technology process is complex, involving multiple high-precision processing steps, and strict conditions need to be controlled for each step, with extremely high requirements for equipment and technology, resulting in very high production costs. Moreover, the entire preparation process takes a long time and is not suitable for large-scale rapid production. The UV-LIGA technology uses ultraviolet lithography to replace traditional X-ray lithography, reducing costs and simplifying the process flow, and combining micro-nano process technology has a positive effect on the preparation of microprobes. However, its resolution and aspect ratio are usually lower than those of traditional LIGA technology. This limits its application in the preparation of microprobes that require extremely high precision and aspect ratio.

[0004] The existing methods generally have the following defects: high process complexity, requiring multi-step precise control (such as temperature, pressure, etching conditions); high cost, relying on high-precision equipment (such as injection molding machines, lithography machines, vacuum etching equipment); limited production scale, low efficiency of 3D printing and LIGA technology, making it difficult to mass-produce; insufficient precision, casting methods are prone to structural defects, and wet etching results in inclined sidewalls.

[0005] Therefore, those skilled in the art have provided a method for preparing a flexible array of microprobes to solve the problems raised in the above background art. Summary of the Invention

[0006] The object of the present invention is to provide a method for preparing a flexible array of microprobes to solve the problems raised in the above background art.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A method for preparing a flexible array of microprobes includes the following steps:

[0009] Step S1: Provide a fused silica substrate and perform organic cleaning. The cleaning process includes three-step ultrasonic cleaning with acetone - isopropanol - deionized water. The ultrasonic power is 50 - 200 W, and the time is 5 - 15 minutes. After cleaning, it is dried in a vacuum oven at 80 °C for 30 minutes;

[0010] Step S2: Prepare an ultraviolet narrowband filter film on a quartz glass substrate. The filter film adopts an HfO2 / SiO2 alternating film layer structure, and the film layer design meets the following transmittance requirements:

[0011] T(λ) ≥ 80% (within the target wavelength band);

[0012] And the out-of-band rejection ratio ≥ 30 dB;

[0013] Step S3: Deposit a Cr / CrOx composite metal film layer on the other side of the filter film by magnetron sputtering, and perform photolithography and reactive ion etching (RIE) to form a micron-scale circular hole array. The etching selectivity meets:

[0014]

[0015] Where: R Cr Is the etching rate of Cr, R PR Is the etching rate of photoresist;

[0016] Step S4: Spin-coat a positive photoresist on the Cr / CrO x film layer, and form a micron-scale circular hole array through photolithography and dry etching. The etching parameters are: etching gas Cl2:O2:Ar = 40:8:10 sccm, radio frequency power 150 W, vacuum degree 20 mTorr; the obtained circular hole diameter is 5 - 50 μm, the period is 10 - 200 μm, and the depth-to-width ratio ≥ 5:1;

[0017] Step S5: Coat a UV glue on the etched Cr film surface and expose and cure it as a probe substrate. The coating parameters are: the UV glue selects the SU-8 2000 series or Loctite 3526; the spin-coating speed is 500 - 3000 rpm, the glue layer thickness is 50 - 200 μm, and the thickness uniformity is within ±3%;

[0018] Step S6: Perform plasma activation treatment on the UV glue film layer. The treatment parameters are: the ratio of O2 / Ar mixed gas is 1:3, the power is 100 - 300 W, the air pressure is 10 - 50 Pa, and the time is 5 - 10 minutes;

[0019] Step S7: Coat a negative photoresist SU-8 2010 on the activated surface and expose it through the Bessel diffraction light field generated by the microporous array. The light intensity distribution I(r,z) is approximately a Bessel function: Where J0 is the zero-order Bessel function and α is the light absorption coefficient.

[0020] Step S8: After development, form a high aspect ratio flexible array of micro needles. The development parameters are: the developer is propylene glycol methyl ether acetate, and the development time is 2 - 10 minutes; the cone angle θ of the obtained micro needles satisfies: ΔI is the radial light intensity change rate;

[0021] Step S9: Separate the membrane layer to obtain the final flexible array microneedle structure.

[0022] As a further solution of the present invention: The film layer structure of the ultraviolet narrow-band filter film in the step S2 is any one of the following:

[0023] a) For the 360 - 370 nm band, adopt an 18-layer structure of "Air|L(HL)^4 2H(LH)^4|Substruct", and the film layer thickness is:

[0024] Substruct|HfO2(44.98nm) / SiO2(63.54nm) / ... / SiO2(118.79nm)|Air;

[0025] b) For the 400 - 410 nm band, adopt an 18-layer structure of "Air|L(HL)^4 2H(LH)^4|Substruct", and the film layer thickness is:

[0026] Substruct|HfO2(36.28nm) / SiO2(63.04nm) / ... / SiO2(49.53nm)|Air;

[0027] c) For the 430 - 440 nm band, adopt a 26-layer structure of "Air|LH···LH|Substruct", and the film layer thickness is:

[0028] Substruct|HfO2(27.44nm) / SiO2(64.63nm) / ... / SiO2(127.70nm)|Air.

[0029] As a further solution of the present invention: The optical properties of the microhole array in the step S7 satisfy that the relationship between the pore diameter d and the exposure wavelength λ is: where NA is the numerical aperture of 0.3 - 0.6; the pore period p satisfies: p ≥ d + 2δ, and δ is the light field diffusion distance of 1 μm.

[0030] As a further solution of the present invention: The curing process of the UV glue in the step S5 satisfies the kinetic model: where C is the crosslinking degree, k0 is the pre-exponential factor, E a is the activation energy, I is the light intensity, and m / n is the reaction order.

[0031] As a further solution of the present invention: The exposure dose D of the negative photoresist in the step S7 satisfies: where D0 is the surface dose of 100 - 500 mJ / cm 2 , L p is the light penetration depth.

[0032] As a further aspect of the present invention: in the step S6, the ion density n of the plasma activation treatment i satisfies: where n e is the electron density, and T e is the electron temperature of 2 - 5 eV.

[0033] As a further aspect of the present invention: the microneedles in the step S8 have the following characteristics:

[0034] 1) Aspect ratio ≥ 5:1;

[0035] 2) The elastic modulus E satisfies: where E0 is the bulk material modulus, and t / L is the thickness - to - length ratio;

[0036] 3) Fracture toughness K_IC ≥ 0.8 MPa·m^1 / 2.

[0037] As a further aspect of the present invention: in the step S3, the thickness of the CrOx transition layer is 10 - 30 nm, and the deposition parameters are: Ar:O2 = 3:1, the total flow rate ≤ 40 sccm, and the vacuum degree is 1.0×10 -3 - 5×10 -1 Pa; the thickness of the Cr layer is 20 - 190 nm, and the deposition parameters are: the argon gas flow rate is 10 - 50 sccm, and the vacuum degree is 0.4 - 0.8 Pa.

[0038] As a further aspect of the present invention: in the step S2:

[0039] For the 360 - 370 nm wavelength band: the average transmittance ≥ 80.5%, and the peak transmittance ≥ 99.998% @ 365.38 nm;

[0040] For the 400 - 410 nm wavelength band: the average transmittance ≥ 85.2%, and the peak transmittance ≥ 99.89% @ 404.85 nm;

[0041] For the 430 - 440 nm wavelength band: the average transmittance ≥ 65.5%, and the peak transmittance ≥ 99.90% @ 435.94 nm.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] 1. Single - wavelength light field sharpening: An ultraviolet narrow - band filter is designed for the exposure light source of a wide - spectrum lithography machine (mercury lamp spectrum range 300 - 600 nm), achieving selective transmission of specific wavelengths. The narrow - band filter improves the clarity of the diffraction light field and the smoothness of the microneedle sidewalls;

[0044] 2. Process Simplification: This technical solution does not require complex mask exposure equipment or the preparation of gray-scale masks. Through the design of ultraviolet narrow-band filters and diffraction light field control technology, the process flow is simplified, the geometric accuracy of the microneedles is improved, and the process cost is reduced. 3. Batch Production: It is suitable for the manufacture of large-area flexible array microprobes. Description of the Drawings

[0045] Figure 1 It is the mercury lamp spectrum diagram of the broadband lithography machine in the present invention;

[0046] Figure 2 It is the transmission curve diagram of JGS1 quartz glass in the present invention;

[0047] Figure 3 It is the diffraction light field distribution diagram of the 365nm light beam passing through a 4um hole in the present invention;

[0048] Figure 4 It is the schematic diagram of the process preparation flow of the flexible array microprobe in the present invention;

[0049] Figure 5 It is the transmittance curve diagram of the ultraviolet filter in the 360nm - 370nm band in the present invention;

[0050] Figure 6 It is the transmittance curve diagram of the ultraviolet filter in the 400nm - 410nm band in the present invention;

[0051] Figure 7 It is the transmittance curve diagram of the ultraviolet filter in the 430nm - 440nm band in the present invention. Detailed Description of the Invention

[0052] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0053] As Figure 1-4 shown, a preparation method of a flexible array microprobe, the preparation process includes the following steps:

[0054] Step S1: Provide a quartz glass substrate and perform organic cleaning treatment. The cleaning process includes three-step ultrasonic cleaning of acetone - isopropyl alcohol - deionized water, with an ultrasonic power of 50 - 200W and a time of 5 - 15 minutes. After cleaning, it is dried in a vacuum oven at 80°C for 30 minutes;

[0055] Step S2, prepare an ultraviolet narrowband filter film on a quartz glass substrate. The filter film adopts an HfO2 / SiO2 alternating film layer structure, and the film layer design meets the following transmittance requirements:

[0056] T(λ) ≥ 80% (within the target wavelength band);

[0057] And the out-of-band rejection ratio ≥ 30 dB;

[0058] Step S3, deposit a Cr / CrOx composite metal film layer on the other side of the filter film by magnetron sputtering, and perform photolithography and reactive ion etching (RIE) to form a micron-scale circular hole array. The etching selectivity meets:

[0059]

[0060] Where: R Cr is the Cr etching rate, and R PR is the photoresist etching rate;

[0061] Step S4, spin-coat a positive photoresist on the Cr / CrO x film layer, and form a micron-scale circular hole array through photolithography and dry etching. The etching parameters are: etching gases Cl2:O2:Ar = 40:8:10 sccm, radio frequency power 150 W, vacuum degree 20 mTorr; the obtained circular hole aperture is 5 - 50 μm, the period is 10 - 200 μm, and the aspect ratio ≥ 5:1;

[0062] Step S5, coat a UV glue on the etched Cr film surface and expose and cure it as a probe substrate. The coating parameters are: the UV glue selects the SU-8 2000 series or Loctite 3526; the spin-coating speed is 500 - 3000 rpm, the glue layer thickness is 50 - 200 μm, and the thickness uniformity is within ±3%;

[0063] Step S6, perform plasma activation treatment on the UV glue film layer. The treatment parameters are: the O2 / Ar mixed gas ratio is 1:3, the power is 100 - 300 W, the air pressure is 10 - 50 Pa, and the time is 5 - 10 minutes;

[0064] Step S7, coat a negative photoresist SU-8 2010 on the activated surface, and expose it through the Bessel diffraction light field generated by the microporous array. The light intensity distribution I(r,z) is approximately the Bessel function: Where J0 is the zero-order Bessel function and α is the light absorption coefficient.

[0065] Step S8, form a high aspect ratio flexible array micro-needle after development. The development parameters are: the developer is propylene glycol methyl ether acetate, and the development time is 2 - 10 minutes; the cone angle θ of the obtained micro-needle satisfies: ΔI is the radial light intensity change rate;

[0066] Step S9: Separate the membrane layer to obtain the final flexible array microneedle structure.

[0067] By adopting the above technical solution, in Steps 1, 4, and 7, through the integrated process of "ultraviolet narrow-band filter + Bessel light field exposure", the 5-7 lithography processes of traditional MEMS are simplified to 3 core steps. An ultraviolet narrow-band filter is designed for the exposure light source of a wide-spectrum lithography machine (mercury lamp spectral range 300 - 600 nm), achieving selective transmission of specific wavelengths. The narrow-band filter improves the clarity of the diffraction light field and the smoothness of the microneedle sidewalls. Moreover, complex mask exposure equipment or gray-scale mask preparation is not required. Through the ultraviolet narrow-band filter design and diffraction light field regulation technology, the process flow is simplified, the geometric accuracy of the microneedles is improved, the process cost is reduced, and it is applicable to the manufacture of large-area flexible array microprobes.

[0068] The film layer structure of the ultraviolet narrow-band filter film in Step S2 is any of the following:

[0069] a) For the 360 - 370 nm band, adopt an 18-layer structure of "Air|L(HL)^4 2H(LH)^4|Substruct", and the film layer thickness is:

[0070] Substruct|HfO2(44.98nm) / SiO2(63.54nm) / ... / SiO2(118.79nm)|Air;

[0071] b) For the 400 - 410 nm band, adopt an 18-layer structure of "Air|L(HL)^4 2H(LH)^4|Substruct", and the film layer thickness is:

[0072] Substruct|HfO2(36.28nm) / SiO2(63.04nm) / ... / SiO2(49.53nm)|Air;

[0073] c) For the 430 - 440 nm band, adopt a 26-layer structure of "Air|LH···LH|Substruct", and the film layer thickness is:

[0074] Substruct|HfO2(27.44nm) / SiO2(64.63nm) / ... / SiO2(127.70nm)|Air.

[0075] Among them, the optical characteristics of the micropore array in Step S7 satisfy that the relationship between the pore diameter d and the exposure wavelength λ is: where NA is the numerical aperture of 0.3 - 0.6; the pore period p satisfies: p ≥ d + 2δ, and δ is the light field diffusion distance of 1 μm.

[0076] Among them, the curing process of the UV glue in step S5 satisfies the kinetic model: where C is the crosslinking degree, k0 is the pre-exponential factor, and E a is the activation energy, I is the light intensity, and m / n is the reaction order, realizing automatic control of process parameters and reducing human intervention.

[0077] Among them, the exposure dose D of the negative photoresist in step S7 satisfies: where D0 is the surface dose of 100 - 500 mJ / cm 2 , and L p is the light penetration depth.

[0078] Among them, the ion density n of the plasma activation treatment in step S6 i satisfies: where n e is the electron density, and T e is the electron temperature of 2 - 5 eV.

[0079] Among them, the microneedles in step S8 have the following characteristics:

[0080] 1) Aspect ratio ≥ 5:1;

[0081] 2) The elastic modulus E satisfies: where E0 is the bulk material modulus, and t / L is the thickness-to-length ratio;

[0082] 4) Fracture toughness K_IC ≥ 0.8 MPa·m^1 / 2.

[0083] Among them, the thickness of the CrOx transition layer in step S3 is 10 - 30 nm, and the deposition parameters are: Ar:O2 = 3:1, total flow rate ≤ 40 sccm, vacuum degree 1.0×10 -3 -5×10 -1 Pa; the thickness of the Cr layer is 20 - 190 nm, and the deposition parameters are: argon flow rate 10 - 50 sccm, vacuum degree 0.4 - 0.8 Pa.

[0084] Among them, in step S2:

[0085] For the 360 - 370 nm band: average transmittance ≥ 80.5%, peak transmittance ≥ 99.998% @ 365.38 nm;

[0086] For the 400 - 410 nm band: average transmittance ≥ 85.2%, peak transmittance ≥ 99.89% @ 404.85 nm;

[0087] For the 430 - 440 nm band: average transmittance ≥ 65.5%, peak transmittance ≥ 99.90% @ 435.94 nm

[0088] Example 1: Standard Microneedle Array in the 360 - 370 nm Band

[0089] As Figure 4 shown in the process flow diagram of fabricating the flexible array microprobe, Example 1 of the present invention provides a method for fabricating a flexible array probe. The mercury lamp exposure light source of the broadband spectrometer is mainly concentrated in the wavelength range of 350 nm to 450 nm. In Example 1, a UV narrowband filter of 360 - 370 nm (i-line) is designed on one side of the quartz glass plate first, then a Cr metal microhole is designed on the other side of the glass plate to regulate the light field distribution, and finally, a UV glue is coated on the Cr film surface as the substrate of the probe. After coating the UV negative photoresist SU-8 2010 and exposing and developing it, a flexible array microprobe is formed. The specific steps are as follows:

[0090] Step 1, organic cleaning, cleaning the JGS1 quartz glass plate. First, pre-treat the sample with acetone. Immerse the sample to be cleaned in the acetone solution (purity ≥ 99.5%), ensuring that the liquid surface completely covers the sample surface. Set the ultrasonic power to 150 - 200 W and the time to 5 - 15 minutes; after the acetone cleaning program is completed, transfer the sample to the isopropyl alcohol (IPA) solution (purity ≥ 99.9%), and set the ultrasonic parameters: power 150 - 200 W, time 5 - 15 minutes; after the IPA cleaning program is completed, transfer the sample to deionized water (resistivity ≥ 18.2 MΩ·cm) for cleaning, set the ultrasonic parameters: power 50 - 200 W, time 5 - 15 minutes. After the program is completed, transfer the sample to a dust-free environment and dry it with high-purity nitrogen to ensure that there is no water mark residue on the surface. After cleaning, place it in a vacuum oven and dry it at 80°C for 30 minutes.

[0091] Step 2: Prepare an ultraviolet narrowband filter. The filter is designed with an 18-layer film structure of "Air|L(HL)^4 2H(LH)^4|Substruct". The film layer H is a high-refractive-index film material using HfO2 film, and the film layer L is a low-refractive-index film material using SiO2 film. The thickness of the high-refractive-index film layer is 32.23 - 70.82 nm, and the thickness of the low-refractive-index film layer is 39.98 - 118.79 nm. The average transmittance of ultraviolet light in the 360 - 370 nm band reaches over 80.5%, and the maximum transmittance is 99.998% @ 365.38 nm. The film thickness from the glass plate to the air layer is Substruct|HfO2(44.98 nm) / SiO2(63.54 nm) / HfO2(48.68 nm) / SiO2(65.60 nm) / HfO2(48.00 nm) / SiO2(70.72 nm) / HfO2(52.93 nm) / SiO2(74.81 nm) / HfO2(70.82 nm) / SiO2(67.32 nm) / HfO2(48.48 nm) / SiO2(70.21 nm) / HfO2(44.39 nm) / SiO2(62.48 nm) / HfO2(44.29 nm) / SiO2(39.98 nm) / HfO2(32.23 nm) / SiO2(118.79 nm)|Air. As Figure 5 shown by the transmittance curve of the ultraviolet filter in the 360 nm - 370 nm band.

[0092] Step 3: Organic cleaning. The relevant processes and process parameters are the same as those in Step 1.

[0093] Step 4: Deposit a chromium metal film layer. Deposit a Cr film on the back of the filter film glass plate by magnetron sputtering. The film structure thickness is CrOx / Cr: 20 nm / 200 nm. The main parameters of the CrOx transition layer deposition process include: gas ratio Ar:O2 = 3:1, the total flow rate is controlled within 40 sccm, the argon flow rate is 5 - 20 sccm, the oxygen flow rate is 0.5 - 5 sccm, the vacuum degree range is 1.0x10-3 - 5x10-1 Pa, the DC power is 100 - 180 W, the substrate temperature is room temperature, and the sputtering rate is controlled at 0.1 - 10 Å / min to obtain a 20 nm thick CrOx layer. The main parameters of the Cr film layer deposition process include: argon flow rate 10 - 50 sccm, vacuum degree range 0.4 - 0.8 Pa, DC power 100 - 500 W; sputtering rate: 0.1 - 5 nm / min, substrate temperature is room temperature.

[0094] Step 5, photolithographic patterning. A positive photoresist (AZ5214) is spin-coated on the CrOx / Cr composite film substrate from the previous step. The main process flow and parameters are as follows: spin-coating speed 4000 rpm, pre-baking temperature 95 °C on a hot plate for 90 seconds, exposure using a SUSS lithography machine, exposure dose 190 mJ / cm 2 ~220 mJ / cm 2 . The developer is selected as TMAH 2.38%, development time 30 s - 45 s, post-baking 120 °C, 120 seconds. Finally, a circular hole array with a photoresist circular hole diameter of 4 μm and a period of 8 μm is formed, and the photoresist thickness is about 1.6 μm.

[0095] Step 6, microhole array etching, using a dry etching process. The background vacuum pressure ≤ 5×10 -6 Torr, the process etching gas ratio is Cl2 40 sccm, O2 8 sccm, Ar 10 sccm, radio frequency power 150 W, vacuum 20 mTorr.

[0096] Step 7, probe substrate preparation. After organic cleaning of the Cr film surface, UV glue is coated and cured by full-surface exposure. The cleaning process is the same as in step 1. SU-8 2035 photoresist is evenly coated on the Cr film surface, spin-coating parameters 500 rpm - 800 rpm speed / 5 - 15 seconds, 1500 rpm - 3000 rpm speed / 30 - 60 seconds, the glue thickness range is 30 - 80 μm, and the thickness uniformity is controlled within ±3%. Pre-baking 65 °C - 75 °C baking / 3 - 5 minutes, 95 °C - 105 °C baking / 5 - 10 minutes. A wide-spectrum ultraviolet light source (mercury lamp intensity 10 - 20 mW / cm 2 ) is used for flood exposure, the exposure dose is 100 - 500 mJ / cm 2 . The exposed substrate is placed on a hot plate for post-baking, and the post-baking temperature is 95 °C - 105 °C / 5 - 15 minutes to promote the full progress of the photosensitive cross-linking reaction in the photoresist, enhance the cross-linking density in the exposed area, and reduce the residual stress.

[0097] Step 8: Fabricate and form the flexible array micro-probes. Clean and activate the UV glue film layer from the previous step. Use a mixed gas of O2 / Ar with a ratio of 1:3, set the power to 100 - 300 W, the air pressure to 10 - 50 Pa, and perform plasma activation treatment on the UV glue film layer for 5 - 10 minutes to enhance the surface's glue affinity. Then coat the SU-8 2010 negative photoresist again, and form a uniform glue layer through a two-stage spin-coating process, with a rotation speed of 500 - 800 rpm for 5 - 15 seconds and a rotation speed of 1500 - 3000 rpm for 30 - 60 seconds, to form a photoresist layer with a thickness of 10 - 20 μm, and the thickness uniformity ≤ ±3%. Pre-bake at 65 - 75 °C for 3 - 5 minutes and at 95 - 105 °C for 5 - 10 minutes. Exposure is carried out using a wide-spectrum lithography machine such as SUSS or EVG, with an exposure dose of 100 - 500 mJ / cm 2 , and the exposure time is 10 - 60 seconds. Post-bake at 95 - 105 °C for 5 - 15 minutes. Development: Immerse the substrate in a propylene glycol methyl ether acetate (PGMEA) developer for 2 - 10 minutes, rinse with isopropyl alcohol (IPA) for 10 - 30 seconds, and rinse with deionized water for 1 - 3 minutes to remove the residual developer. Generate a diffraction light field through the round holes on the back, and the light intensity distribution shows the characteristics of a Bessel function, forming a conical light intensity gradient. After development, the photoresist retains the gradient exposure area, forming high-aspect-ratio conical flexible array micro-probes.

[0098] Step 9: Separate the membrane layer to obtain the flexible array micro-probe structure.

[0099] In this embodiment, the standard micro-probe array data in the 360 - 370 nm band is tested, and the results are as follows:

[0100]

[0101]

[0102] Example 2: High-aspect-ratio micro-probes in the 400 - 410 nm band

[0103] In this embodiment, first, a UV narrow-band filter in the 400 - 410 nm (h-line) is designed on one side of a quartz glass plate, then Cr metal micro-holes are designed on the other side of the glass plate for light field regulation, and finally, a UV glue is coated on the Cr film surface as the substrate for the flexible micro-probes. After coating the UV negative photoresist SU-8 2010 and performing exposure and development, flexible array micro-probes are formed. The specific steps are as follows:

[0104] Step 1, organic cleaning, clean the JGS1 quartz glass plate. First, pretreat the sample with acetone. Immerse the sample to be cleaned in an acetone solution (purity ≥ 99.5%), ensuring that the liquid surface completely covers the sample surface. Set the ultrasonic power to 150 - 200 W and the time to 5 - 15 minutes. After the acetone cleaning process is completed, transfer the sample to an isopropyl alcohol (IPA) solution (purity ≥ 99.9%), and set the ultrasonic parameters: power 150 - 200 W and time 5 - 15 minutes. After the isopropyl alcohol cleaning process is completed, transfer the sample to deionized water (resistivity ≥ 18.2 MΩ·cm) for cleaning, set the ultrasonic parameters: power 50 - 200 W and time 5 - 15 minutes. After the process is completed, transfer the sample to a dust-free environment and blow it dry with high-purity nitrogen to ensure that there is no water mark residue on the surface. After cleaning, place it in a vacuum oven and dry it at 80°C for 30 minutes.

[0105] Step 2, prepare an ultraviolet narrowband filter. The filter adopts an 18-layer film structure design of "Air|L(HL)^4 2H(LH)^4|Substruct". The film layer H is a high-refractive-index film material using HfO2 film material, and the film layer L is a low-refractive-index film material using SiO2 film material. The thickness of the high-refractive-index film layer is 36.28 - 103.38 nm, and the thickness of the low-refractive-index film layer is 49.53 - 81.26 nm. In the 400 - 410 nm wavelength band, the average ultraviolet light transmittance reaches more than 85.2%, and the maximum transmittance reaches 99.89% @ 404.85 nm. The film layer thickness from the glass plate to the air layer is Substruct|HfO2(36.28nm) / SiO2(63.04nm) / HfO2(50.44nm) / SiO2(70.20nm) / HfO2(47.13nm) / SiO2(60.28nm) / HfO2(47.40nm) / SiO2(81.26nm) / HfO2(103.38nm) / SiO2(67.63nm) / HfO2(52.84nm) / SiO2(62.53nm) / HfO2(50.31nm) / SiO2(66.17nm) / HfO2(50.37nm) / SiO2(70.49nm) / HfO2(58.58nm) / SiO2(49.53nm)|Air. As Figure 6 shown by the transmittance curve of the ultraviolet filter in the 400 nm - 410 nm wavelength band.

[0106] Step 3, organic cleaning, the relevant processes and process parameters are the same as in Step 1.

[0107] Step 4: Depositing a chromium metal film layer. A Cr film is deposited on the back of the filter film layer glass plate by magnetron sputtering. The film layer structure thickness is CrOx / Cr: 20 nm / 200 nm. The main parameters of the CrOx transition layer deposition process include: gas ratio Ar:O2 = 3:1, total flow rate controlled within 40 sccm, argon flow rate 5 - 20 sccm, oxygen flow rate 0.5 - 5 sccm, vacuum degree range 1.0x10-3 - 5x10-1 Pa, DC power 100 - 180 W, substrate temperature at room temperature, sputtering rate controlled at 0.1 - 10 Å / min to obtain a 20-nm-thick CrOx layer. The main parameters of the Cr film layer deposition process include: argon flow rate 10 - 50 sccm, vacuum degree range 0.4 - 0.8 Pa, DC power 100 - 500 W; sputtering rate: 0.1 - 5 nm / min, substrate temperature at room temperature.

[0108] Step 5: Lithographic patterning. A positive photoresist (AZ5214) is spin-coated on the CrOx / Cr composite film layer substrate in the previous step. The main process flow and parameters are: spin-coating speed 4000 rpm, pre-baking temperature baked on a hot plate at 95 °C for 90 seconds, exposed using a SUSS lithography machine, exposure dose at 190 mJ / cm 2 ~220 mJ / cm 2 , the developer is selected as TMAH 2.38%, development time 30 s - 45 s, post-baking at 120 °C for 120 seconds, finally forming a circular hole array of photoresist with a circular hole diameter of 4 μm and a period of 8 μm, and the photoresist thickness is about 1.6 μm.

[0109] Step 6: Microhole array etching, using a dry etching process method. The background vacuum pressure ≤ 5×10 -6 Torr, the process etching gas ratio is Cl2 40 sccm, O2 8 sccm, Ar 10 sccm, RF power 150 W, vacuum degree 20 mTorr.

[0110] Step 7: Probe substrate preparation. After organic cleaning of the Cr film surface, UV glue is coated and exposed and cured over the entire surface. The cleaning process is the same as in Step 1. SU-8 2035 photoresist is evenly coated on the Cr film surface, spin-coating parameters are 500 rpm - 800 rpm speed / 5 - 15 seconds, 1500 rpm - 3000 rpm speed / 30 - 60 seconds, the glue thickness range is 30 - 80 μm, and the thickness uniformity is controlled within ±3%. Pre-baking at 65 °C - 75 °C for 3 - 5 minutes, 95 °C - 105 °C for 5 - 10 minutes. A UV broad-spectrum light source (mercury lamp intensity 10 - 20 mW / cm 2 ) is used for flood exposure, and the exposure dose is 100 - 500 mJ / cm 2, the exposed substrate is placed on a hot plate for post-baking, and the post-baking temperature is 95°C to 105°C for 5 - 15 minutes to promote the full progress of the photosensitive cross-linking reaction in the photoresist, enhance the cross-linking density in the exposed area, and reduce the residual stress.

[0111] Step 8, preparation and molding of the flexible array micro-probe. Clean and activate the UV film layer in the previous step. Use a mixed gas of O2 / Ar with a ratio of 1:3, set the power to 100 - 300W, and the air pressure to 10 - 50Pa. Perform plasma activation treatment on the UV film layer for 5 - 10 minutes to enhance the surface's adhesiveness to the glue. Then coat the SU-8 2010 negative photoresist again, and form a uniform glue layer through a two-stage spin-coating process, with a rotation speed of 500 - 800rpm for 5 - 15 seconds and a rotation speed of 1500 - 3000rpm for 30 - 60 seconds, to form a photoresist layer with a thickness of 10 - 20μm, and the thickness uniformity is ≤ ±3%. Pre-bake at 65 - 75°C for 3 - 5 minutes and at 95 - 105°C for 5 - 10 minutes. Exposure is carried out using a wide-spectrum lithography machine such as SUSS or EVG, and the exposure dose is 100 - 500mJ / cm 2 , and the exposure time is 10 - 60 seconds. Post-bake at 95 - 105°C for 5 - 15 minutes. Development: Immerse the substrate in a propylene glycol monomethyl ether acetate (PGMEA) developer for 2 - 10 minutes, rinse with isopropyl alcohol (IPA) for 10 - 30 seconds, and rinse with deionized water for 1 - 3 minutes to remove the residual developer. Generate a diffraction light field through the circular hole on the back, and the light intensity distribution exhibits the characteristics of a Bessel function, forming a conical light intensity gradient. After development, the photoresist retains the gradient-exposed area, forming high-aspect-ratio conical flexible array micro-needles.

[0112] Step 9, separate the film layer to obtain the flexible array micro-needle structure.

[0113] In this embodiment, the data of high-aspect-ratio micro-needles in the 400 - 410nm band are tested, and the results are as follows:

[0114]

[0115] Example 3: Drug-loaded micro-needles in the 430 - 440nm band

[0116] In the embodiment of the present invention, first, a UV narrow-band filter in the 430 - 440nm (g-line) is designed on one side of a quartz glass plate, then Cr metal micro-holes are designed on the other side of the glass plate for light field regulation, and finally, a UV glue is coated on the Cr film surface as the substrate of the flexible micro-needle. After coating the UV negative photoresist SU-8 2010 and exposure and development, a flexible array micro-probe is formed. The specific steps are as follows:

[0117] Step 1: Organic cleaning. Clean the JGS1 quartz glass plate. First, pre-treat the sample with acetone. Immerse the sample to be cleaned in an acetone solution (purity ≥ 99.5%), ensuring that the liquid level completely covers the sample surface. Set the ultrasonic power to 150 - 200 W and the time to 5 - 15 minutes. After the acetone cleaning procedure is completed, transfer the sample to an isopropyl alcohol (IPA) solution (purity ≥ 99.9%), and set the ultrasonic parameters: power 150 - 200 W, time 5 - 15 minutes. After the isopropyl alcohol cleaning procedure is completed, transfer the sample to deionized water (resistivity ≥ 18.2 MΩ·cm) for cleaning, set the ultrasonic parameters: power 50 - 200 W, time 5 - 15 minutes. After the procedure is completed, transfer the sample to a dust-free environment and dry it with high-purity nitrogen to ensure no water marks remain on the surface. After cleaning, place it in a vacuum oven and dry at 80°C for 30 minutes.

[0118] Step 2: Prepare an ultraviolet narrow-band filter. The filter adopts a 26-layer film structure design of "Air|LH···LH|Substruct". The film layer H is a high-refractive-index film material using HfO2 film material, and the film layer L is a low-refractive-index film material using SiO2 film material. The thickness of the high-refractive-index film layer is 27.44 - 146.33 nm, and the thickness of the low-refractive-index film layer is 62.36 - 127.70 nm. In the 430 - 440 nm band, the average ultraviolet light transmittance reaches more than 65.5%, and the maximum transmittance reaches 99.90% @ 435.94 nm. The film layer thickness from the glass plate to the air layer is Substruct|HfO2(27.44nm) / SiO2(64.63nm) / HfO2(146.33nm) / SiO2(82.10nm) / HfO2(61.46nm) / SiO2(79.51nm) / HfO2(60.30nm) / SiO2(66.97nm) / HfO2(48.12nm) / SiO2(70.11nm) / HfO2(43.85nm) / SiO2(63.80nm) / HfO2(142.03nm) / SiO2(62.36nm) / HfO2(44.55nm) / SiO2(75.71nm) / HfO2(44.37nm) / SiO2(67.30nm) / HfO2(51.54nm) / SiO2(72.82nm) / HfO2(85.10nm) / Si O2(106.10nm) / HfO2(48.55nm) / SiO2(71.27nm) / HfO2(45.89nm) / SiO2(127.70nm)|Air. As Figure 7 shown by the transmittance curve of the ultraviolet filter in the 430 nm - 440 nm band.

[0119] Step 3: Organic cleaning. The relevant processes and process parameters are the same as those in Step 1.

[0120] Step 4: Depositing a chromium metal film layer. A Cr film is deposited on the back of the filter film layer glass plate by magnetron sputtering. The film layer structure thickness is CrOx / Cr: 20 nm / 200 nm. The main parameters of the CrOx transition layer deposition process include: gas ratio Ar:O2 = 3:1, total flow rate controlled within 40 sccm, argon flow rate 5 - 20 sccm, oxygen flow rate 0.5 - 5 sccm, vacuum degree range 1.0x10-3 - 5x10-1 Pa, DC power 100 - 180 W, substrate temperature at room temperature, sputtering rate controlled at 0.1 - 10 Å / min to obtain a 20 nm thick CrOx layer. The main parameters of the Cr film layer deposition process include: argon flow rate 10 - 50 sccm, vacuum degree range 0.4 - 0.8 Pa, DC power 100 - 500 W; sputtering rate: 0.1 - 5 nm / min, substrate temperature at room temperature.

[0121] Step 5: Lithographic patterning. A positive photoresist (AZ5214) is spin-coated on the CrOx / Cr composite film layer substrate in the previous step. The main process flow and parameters are: spin-coating speed 4000 rpm, pre-baking temperature baked on a hot plate at 95 °C for 90 seconds, exposed using a SUSS lithography machine, exposure dose between 190 mJ / cm 2 ~220 mJ / cm 2 , the developer is selected as TMAH 2.38%, development time 30 s - 45 s, post-baking at 120 °C for 120 seconds, finally forming a circular hole array of photoresist with a hole diameter of 4 μm and a period of 8 μm, and the photoresist thickness is about 1.6 μm.

[0122] Step 6: Microhole array etching. The dry etching process method is adopted. The background vacuum pressure ≤ 5×10 -6 Torr, the process etching gas ratio is Cl2 40 sccm, O2 8 sccm, Ar 10 sccm, RF power 150 W, vacuum degree 20 mTorr.

[0123] Step 7: Probe substrate preparation. After organic cleaning the Cr film surface, UV glue is coated and cured by full-surface exposure. The cleaning process is the same as in Step 1. SU-8 2035 photoresist is evenly coated on the Cr film surface, spin-coating parameters are 500 rpm - 800 rpm speed / 5 - 15 seconds, 1500 rpm - 3000 rpm speed / 30 - 60 seconds, the glue thickness range is 30 - 80 μm, and the thickness uniformity is controlled within ±3%. Pre-baking is baked at 65 °C - 75 °C for 3 - 5 minutes, and at 95 °C - 105 °C for 5 - 10 minutes. A UV broad-spectrum light source (mercury lamp intensity 10 - 20 mW / cm 2 ) is used for flood exposure, and the exposure dose is 100 - 500 mJ / cm2 After exposure, the substrate is placed on a hot plate for post-baking at a temperature of 95°C to 105°C for 5 - 15 minutes to promote the full progress of the photosensitive cross-linking reaction in the photoresist, enhance the cross-linking density in the exposed area, and reduce the residual stress.

[0124] Step 8: Fabrication and shaping of the flexible array microprobes. The UV film layer from the previous step is cleaned and activated using a mixed gas of O2 / Ar with a ratio of 1:3, a set power of 100 - 300 W, and a gas pressure of 10 - 50 Pa for 5 - 10 minutes of plasma activation treatment on the UV film layer to enhance the surface's affinity for the glue. Then, SU-8 2010 negative photoresist is coated again, and a uniform glue layer is formed through a two-stage spin-coating process, at a rotation speed of 500 - 800 rpm for 5 - 15 seconds and 1500 - 3000 rpm for 30 - 60 seconds, to form a photoresist layer with a thickness of 10 - 20 μm and a thickness uniformity of ≤ ±3%. Pre-baking is carried out at 65 - 75°C for 3 - 5 minutes and 95 - 105°C for 5 - 10 minutes. Exposure is performed using a wide-spectrum lithography machine such as SUSS or EVG, with an exposure dose of 100 - 500 mJ / cm 2 , an exposure time of 10 - 60 seconds. Post-baking is carried out at 95 - 105°C for 5 - 15 minutes. Development: The substrate is immersed in a propylene glycol methyl ether acetate (PGMEA) developer for 2 - 10 minutes, rinsed with isopropyl alcohol (IPA) for 10 - 30 seconds, and washed with deionized water for 1 - 3 minutes to remove the residual developer. A diffracted light field is generated through the round hole on the back surface, and the light intensity distribution exhibits the characteristics of a Bessel function, forming a conical light intensity gradient. After development, the photoresist retains the gradient-exposed area, forming high aspect ratio conical flexible array micro needles.

[0125] Step 9: Separate the film layer to obtain the flexible array micro needle structure.

[0126] In this embodiment, the data of the drug-loaded micro needles in the 430 - 440 nm band are tested, and the results are as follows:

[0127]

[0128] For the test data of Examples 1 - 3, they are all from 3 independent repeated experiments (n ≥ 30), and statistical analysis is carried out using OriginPro, with the error bars representing ±SD.

[0129] From the data analysis of Examples 1 - 3, it can be seen that: Bessel light field exposure improves the feature size control ability by 2.3 times (compared with traditional lithography); plasma activation treatment increases the cell adhesion rate by 41.5% (compared with the untreated group); the CV of the micro needle height on a 4-inch wafer is < 1.5%, which is better than the industry standard of 5%; the same process platform can simultaneously meet the requirements of drug delivery (Example 3) and electrophysiology (Example 4).

[0130] As described above, it is only the preferred specific embodiment of the present invention. However, the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention should cover within the protection scope of the present invention when making equivalent substitutions or changes according to the technical solution and inventive concept of the present invention.

Claims

1. A preparation method of a flexible array microprobe, characterized in that: It includes the following steps: Step S1: Provide a fused silica substrate and perform organic cleaning. The cleaning process includes three-step ultrasonic cleaning with acetone - isopropyl alcohol - deionized water. The ultrasonic power is 50 - 200 W, and the time is 5 - 15 minutes. After cleaning, dry it in a vacuum oven at 80 °C for 30 minutes; Step S2: Prepare an ultraviolet narrow-band filter film on the fused silica substrate. The filter film adopts an HfO2 / SiO2 alternating film layer structure, and the film layer design meets the following transmittance requirements: T(λ)≥80%(within the target band); And the out-of-band rejection ratio ≥ 30 dB; Step S3: Magnetron sputter deposit a Cr / CrOx composite metal film layer on the other side of the filter film, and perform photolithography and reactive ion etching (RIE) to form a micron-level round hole array. The etching selectivity meets: Where: R Cr is the Cr etching rate, and R PR is the photoresist etching rate; Step S4. Spin-coat a positive photoresist on the Cr / CrO x film layer, and form a micron-scale circular hole array through photolithography and dry etching. Etching parameters: etching gases Cl2:O2:Ar = 40:8:10 sccm, radio frequency power 150 W, vacuum degree 20 mTorr; the obtained circular hole has a diameter of 5 - 50 μm, a period of 10 - 200 μm, and an aspect ratio ≥ 5:1; Step S5: Coat a UV glue on the etched Cr film surface and expose and cure it as a probe substrate. Coating parameters: The UV glue selects the SU-8 2000 series or Loctite 3526; The spin coating speed is 500 - 3000 rpm, the glue layer thickness is 50 - 200 μm, and the thickness uniformity is within ±3%; Step S6: Perform plasma activation treatment on the UV glue film layer. Treatment parameters: The O2 / Ar mixed gas ratio is 1:3, the power is 100 - 300 W, the air pressure is 10 - 50 Pa, and the time is 5 - 10 minutes; Step S7: Coating a negative photoresist SU-8 2010 on the activated surface, and performing exposure through the Bessel diffraction light field generated by the microporous array. The light intensity distribution I(r,z) is approximated by the Bessel function: where J0 is the zero-order Bessel function and α is the light absorption coefficient. Step S8: After development, high aspect ratio flexible array microneedles are formed. The development parameters are as follows: the developer is propylene glycol methyl ether acetate, and the development time is 2 to 10 minutes. The cone angle θ of the obtained microneedles satisfies: ΔI is the radial light intensity change rate; Step S9: Separate the film layer to obtain the final flexible array microneedle structure.

2. The preparation method of a flexible array microprobe according to claim 1, wherein: In the said step S2, the film layer structure of the ultraviolet narrow-band filter film is any one of the following: a) For the 360 - 370 nm band, adopt an 18-layer structure of "Air|L(HL)^4 2H(LH)^4|Substruct", and the film layer thickness is: Substruct|HfO2(44.98nm) / SiO2(63.54nm) / ... / SiO2(118.79nm)|Air; b) For the 400 - 410 nm band, adopt an 18-layer structure of "Air|L(HL)^4 2H(LH)^4|Substruct", and the film layer thickness is: Substruct|HfO2(36.28nm) / SiO2(63.04nm) / ... / SiO2(49.53nm)|Air; c) For the 430 - 440 nm band, adopt a 26-layer structure of "Air|LH···LH|Substruct", and the film layer thickness is: Substruct|HfO2(27.44nm) / SiO2(64.63nm) / ... / SiO2(127.70nm)|Air.

3. The preparation method of a flexible array microprobe according to claim 1, characterized in that: In the step S7, the optical characteristics of the microhole array satisfy that the relationship between the pore diameter d and the exposure wavelength λ is: where NA is the numerical aperture of 0.3 to 0.6; the pore period p satisfies: p ≥ d + 2δ, and δ is the optical field diffusion distance of 1 μm.

4. The preparation method of a flexible array microprobe according to claim 1, characterized in that: The curing process of the UV glue in step S5 satisfies the kinetic model: where C is the degree of crosslinking, k0 is the pre-exponential factor, E a is the activation energy, I is the light intensity, and m / n is the reaction order.

5. The preparation method of a flexible array microprobe according to claim 1, wherein: In the step S7, the exposure dose D of the negative photoresist satisfies: where D0 is the surface dose of 100 - 500 mJ / cm 2 , L p is the light penetration depth.

6. The preparation method of a flexible array microprobe according to claim 1, wherein: The ion density n in the plasma activation treatment in step S6 i satisfies: where n e is the electron density, and T e is the electron temperature of 2 - 5 eV.

7. The preparation method of a flexible array microprobe according to claim 1, wherein: In the said step S8, the microneedles have the following characteristics: 1) Aspect ratio ≥ 5:1; 2) The elastic modulus E satisfies: where E0 is the bulk material modulus and t / L is the thickness-to-length ratio; 3) Fracture toughness K_IC≥0.8 MPa·m^1 / 2.

8. The preparation method of a flexible array microprobe according to claim 1, characterized in that: In the step S3, the thickness of the CrOx transition layer is 10 - 30 nm, and the deposition parameters are: Ar:O2 = 3:1, the total flow rate ≤ 40 sccm, and the vacuum degree is 1.0×10 -3 ~5×10 -1 Pa; the thickness of the Cr layer is 20 - 190 nm, and the deposition parameters are: the argon gas flow rate is 10 - 50 sccm, and the vacuum degree is 0.4 - 0.8 Pa.

9. The preparation method of a flexible array microprobe according to claim 1, characterized in that: In the said step S2: For the 360 - 370 nm band: Average transmittance ≥ 80.5%, peak transmittance ≥ 99.998%@365.38 nm; For the 400 - 410 nm band: Average transmittance ≥ 85.2%, peak transmittance ≥ 99.89%@404.85 nm; For the 430 - 440 nm band: average transmittance ≥ 65.5%, peak transmittance ≥ 99.90% @ 435.94 nm.

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