An apparatus and method for preparing a three-dimensional microstructure using microprojection

Abstract

The application discloses a device and method for preparing three-dimensional microstructure by micro-projection. The device comprises a pattern generator, a pattern display, a projection light source, a collimating lens, a converging lens, a micro objective, a sample substrate and a Z-axis motion platform. The pattern display, the projection light source, the collimating lens, the converging lens and the micro objective form an optical system. The projection light source generates light of a specific wavelength to control the curing of liquid light-curing material in the form of a micro-pattern. The relative position between the sample substrate and the micro objective is controlled by the Z-axis motion platform, and the pattern generator generates a pattern corresponding to the position to generate a specific three-dimensional microstructure. The application combines digital light processing and liquid crystal display printing to realize light-curing printing forming of three-dimensional microstructure with micron-level precision. The application is simple and easy to realize, the preparation method does not need strict environmental control, and the manufacturing cost of high-precision three-dimensional microstructure is reduced.

Description

Technical Field

[0001] This invention relates to a three-dimensional microstructure fabrication technology, specifically to an apparatus and method for fabricating three-dimensional microstructures using microscopic projection. This invention is applicable to the photopolymerization printing fabrication of optical components such as microlenses and their arrays, and microprisms and their arrays; it is also applicable to the high-precision manufacturing of microstructures such as microchannels; and it is suitable for the fabrication of microstructures from opaque liquid photopolymerization materials. Background Technology

[0002] In recent years, three-dimensional microstructures have played an increasingly important role in many fields such as aerospace, fiber optic communication, biomedicine, and optical computing, and have shown increasingly broad application prospects. Optical microlens arrays are widely used in the field of low-light night vision devices, which can significantly increase the light-capturing area and improve the signal-to-noise ratio; photonic microstructures can modulate light signals at the micrometer or even submicrometer scale to achieve control over the movement of light; biomimetic microstructures are often used in the surface functional design of novel materials for superhydrophobicity, self-cleaning, and fluid drag reduction. At the same time, three-dimensional microstructure devices are also often used as core components of microelectromechanical systems (MEMS).

[0003] Currently, microfabrication technologies used for the fabrication of three-dimensional microstructures mainly fall into two categories: three-dimensional microfabrication technologies based on photolithography and traditional precision machining technologies. The main microstructure fabrication methods include LIGA technology, laser microfabrication technology, silicon-based microfabrication technology, electron beam lithography, micro-electrode machining, nanoimprint lithography, and single-point diamond cutting. LIGA technology is a three-dimensional microstructure fabrication technology based on X-ray photolithography, developed by the Karlsruhe Atomic Energy Research Center in Germany in the 1980s. Its primary purpose at the time was to manufacture micro-nozzles for refining uranium isotopes. LIGA technology can produce tiny metal and plastic devices that are impossible to manufacture using traditional precision machining and has become an important fabrication technology for micro- and nanostructures. Laser microfabrication technology, developed from laser processing technology, uses appropriate lasers as a light source to fabricate micro- and nanostructures at the micrometer scale or even smaller. It offers advantages such as high spatial and temporal resolution, no pollution, non-contact operation, low noise, and intelligent control. Silicon-based micromachining technology employs photolithography masks, dry silicon etching, and wet silicon etching to selectively remove portions of single-crystal silicon material through exposure. Electron beam lithography is an exposure technique that uses an electron beam to directly write or project a template onto a wafer coated with photosensitive emulsion. It shares advantages with LIGA technology and can also fabricate microstructures with arbitrary curved surfaces. Micro-electro-discharge machining (EDM) utilizes the electro-erosion phenomenon caused by pulsed spark discharge between materials and electrodes to fabricate microstructures. It demands high precision in the movement and positioning of the fabrication system, as well as high control and detection of the microstructure fabrication process. It can fabricate complex three-dimensional microstructures at the micrometer scale. Nanoimprint lithography (NIL) technology, developed by the Nanostructure Laboratory at the University of Minnesota, uses a physical forming method. The desired microstructure is first fabricated on a template using other micro / nano processing techniques, and then imprinted onto a nanoimprint lithography adhesive under pressure to replicate the microstructure. Single-point diamond turning technology, through precise control of ultra-precision CNC lathes and the machining environment, utilizes diamond tools for single-point turning to directly fabricate 3D microstructures that meet specific requirements. In recent years, several new methods for fabricating 3D microstructures have emerged. For example, the team led by Zhang Dongxian at the College of Optoelectronics, Zhejiang University, proposed two new methods: one is a laser thermoplastic molding method for fabricating 3D microstructures, using a laser beam to induce thermal expansion in thermoplastic materials, forming protruding microstructures, and completing the fabrication in a liquid environment, allowing for vertical growth of the microstructures; the other is a microstructure fabrication method using capillary microprobes, combining capillary microprobes with localized electrochemical micromachining technology to generate microstructures through electrochemical deposition. Nanoscribe, a subsidiary of Zeiss, has successfully developed a micro / nano 3D printer based on two-photon polymerization, utilizing the spatial selectivity of two-photon absorption to achieve high spatial resolution, capable of printing microstructures with a resolution of less than 100 nm. These technologies and methods provide fabrication routes for 3D microstructures in various application scenarios. Summary of the Invention

[0004] The purpose of this invention is to provide an apparatus and method for fabricating three-dimensional microstructures using microscopic projection. Specifically, it provides an apparatus and method for fabricating three-dimensional microstructural units and arrays such as microlenses, microprisms, and microchannels using photocurable materials based on microscopic projection. This invention utilizes a reverse microscopic optical path to miniaturize patterns displayed on pattern displays such as liquid crystal screens to the object-side focal plane of a microscope objective, and controls the curing of the pattern using liquid photocurable materials. Based on the principle of photocuring, this invention combines digital light processing (DLP) printing and liquid crystal display (LCD) printing to achieve the printing and molding of micron-level three-dimensional microstructures.

[0005] To achieve this objective, the present invention employs the following technical solution:

[0006] An apparatus for fabricating three-dimensional microstructures using microscopic projection includes a pattern generator, a pattern display, a projection light source, a collimating lens, an imaging lens, a microscope objective, a sample substrate, and a Z-axis motion platform, wherein:

[0007] A pattern generator produces a specific pattern, which exists in the form of a grayscale image; a pattern display is used to display the grayscale image generated by the pattern generator; a projection light source is used to generate divergent light of a specific wavelength, and a collimating lens collimates the divergent light into projection light; an imaging lens generates an intermediate image of the pattern displayed on the pattern display between the imaging lens and the microscope objective; the microscope objective displays the intermediate image in miniaturized form on the object-side focal plane of the microscope objective; a sample substrate is used to support the prepared three-dimensional microstructure; and a Z-axis motion platform is used to change the relative distance between the sample substrate and the microscope objective.

[0008] Furthermore, the pattern display, the projection light source, the collimating lens, the imaging lens, and the microscope objective constitute an optical system; the pattern display is located at the image-side focal plane of the imaging lens; the grayscale value of the grayscale image is positively correlated with the transmittance of the pattern display unit, the higher the grayscale value, the greater the transmittance; the pattern on the pattern display has a high grayscale value, allowing the projection light to pass through; the background grayscale value of the pattern is 0, used to block the parallel projection light; the display pattern on the pattern display is an enlarged version of the current cross-sectional pattern of the prepared three-dimensional microstructure, and the magnification is equal to the overall magnification of the optical system.

[0009] Furthermore, the divergent light of a specific wavelength generated by the projection light source is collimated by the collimating lens and then passes sequentially through the pattern display, the imaging lens, and the microscope objective, generating a miniature pattern on the object-side focal plane of the microscope objective; the liquid photocurable material at the object-side focal plane of the microscope objective is solidified in the form of the miniature pattern.

[0010] Furthermore, the sample substrate is made of a metal material or metal alloy with excellent elasticity, and the surface has a microstructure array; the microstructure array is composed of microstructure units with a feature width of less than 500 micrometers and a feature height of less than 100 micrometers; the preferred metal material is manganese or spring steel, and the preferred metal alloy is beryllium copper alloy.

[0011] Furthermore, the microscope objective is a plan objective, preferably an optical infinity plan apochromatic objective.

[0012] A method for preparing three-dimensional microstructures using microscopic projection relies on the aforementioned apparatus for preparing three-dimensional microstructures using microscopic projection, and includes the following steps:

[0013] Step 1: Initialize the position of the Z-axis motion platform so that the bearing surface of the sample substrate is located at the image-side focal plane of the microscope objective.

[0014] Step 2: Add liquid photocurable material so that the bearing surface of the sample substrate is immersed in the liquid photocurable material;

[0015] Step 3: Load the design model of the three-dimensional microstructure and determine the fabrication process parameters such as the reference direction, step distance, movement speed, light intensity, and light exposure time;

[0016] Step 4: Using the reference direction as the normal, starting from the minimum projection position of the three-dimensional microstructure in the reference direction and ending at the maximum projection position of the three-dimensional microstructure in the reference direction, and using the set step distance as the reference, generate the corresponding cross-sectional surfaces of the three-dimensional microstructure at equal intervals, and obtain the corresponding cross-sectional surface patterns.

[0017] Step 5: Turn on the projection light source and set the entire pattern display to grayscale value 0 to block the light emitted by the projection light source from entering the imaging lens;

[0018] Step 6: Taking the current position of the Z-axis motion platform as the starting position, the pattern generator magnifies the cross-sectional pattern corresponding to the starting position according to the overall magnification of the optical system and converts it into a grayscale image.

[0019] Step 7: The pattern generator transmits and displays the grayscale image corresponding to the current position on the pattern display. The projection light source emits light of a specific wavelength at the light intensity set in step 3 and displays the corresponding grayscale image at the image-side focal plane position of the microscope objective. The display duration of the grayscale image is the light duration set in step 3.

[0020] Step 8: Set the pattern display to the minimum grayscale value of 0, block the projection light from entering the imaging lens, move the position of the Z-axis motion platform to increase the distance between the microscope objective and the sample substrate by the step distance set in step 3, extract the cross-section corresponding to the current position, and generate the grayscale image.

[0021] Step 9: Repeat steps 6-8 until the fabrication of the three-dimensional microstructure is complete;

[0022] Step 10: Turn off the projection light source.

[0023] Furthermore, in step 6 above, the specific method for converting the cross-sectional pattern into a grayscale image is as follows: The cross-sectional pattern is drawn by scanning from left to right using horizontal scan lines, with the initial number of intersection points set to 0. Each time the horizontal scan line intersects the boundary of the cross-sectional pattern, the number of intersection points is incremented by 1. When the number of intersection points at the current horizontal position is odd, that position is a filled area; when the number of intersection points at the current horizontal position is even, that position is a non-filled area. The grayscale value of the filled area is set to the maximum grayscale value, and the grayscale value of the non-filled area is set to the minimum grayscale value of 0. Following the above process, the filling and assignment are completed from top to bottom to generate a grayscale image.

[0024] A three-dimensional microstructure photopolymerization printer based on microscopic projection includes the aforementioned apparatus for preparing three-dimensional microstructures using microscopic projection, and prints three-dimensional microstructures using the aforementioned method for preparing three-dimensional microstructures using microscopic projection.

[0025] Furthermore, in the aforementioned three-dimensional microstructure photopolymerization printer based on microscopic projection, the pattern display is a liquid crystal display, and a 45-degree angle beam splitter is located between the pattern display and the imaging lens. Using the beam splitter surface of the 45-degree angle beam splitter as a reference, the imaging target surface of the observation camera is placed at the conjugate position of the pattern display and used to observe the curing process of the cross-sectional pattern of the projected three-dimensional microstructure.

[0026] Furthermore, a three-dimensional microstructure photopolymerization printer based on microscopic projection is provided, wherein the sample substrate is assembled with the Z-axis motion platform through a transfer structure, and the Z-axis motion platform is mounted as a whole on an XY dual-axis motion platform, which can drive the sample substrate to move in the XYZ three-dimensional space; relying on the planar motion of the XY dual-axis motion platform, splicing printing of large-area microstructures can be realized.

[0027] The advantages of this invention over the prior art are as follows:

[0028] First, this invention combines digital light processing (DLP) printing and liquid crystal display (LCD) printing to achieve micron-level precision in the photopolymerization printing of three-dimensional microstructures.

[0029] Secondly, the preparation device provided by the present invention has a simple structure and is easy to implement. The preparation method does not require strict environmental control, which can reduce the manufacturing cost of high-precision three-dimensional microstructures. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the device for preparing three-dimensional microstructures using microscopic projection according to the present invention;

[0031] Figure 2 This is a schematic diagram of embodiment 2 of the device for preparing three-dimensional microstructures using microscopic projection according to the present invention;

[0032] Figure 3 This is a schematic diagram of embodiment 3 of the device for preparing three-dimensional microstructures using microscopic projection according to the present invention;

[0033] Figure 4 This is a flowchart of a method for preparing three-dimensional microstructures using microscopic projection according to the present invention;

[0034] Figure 5 This is a schematic diagram of the method for generating three-dimensional microstructure cross-sectional patterns and grayscale images according to the present invention;

[0035] Figure 6 This is a schematic diagram of the method for converting a cross-sectional pattern into a grayscale image based on the scan line filling algorithm of the present invention;

[0036] Figure 7 This is a schematic diagram of the structure of a three-dimensional microstructure photopolymerization printer based on microscopic projection according to Embodiment 1 of the present invention;

[0037] Figure 8 This is a schematic diagram of the structure of a 2nd embodiment of a three-dimensional microstructure photopolymerization printer based on microscopic projection according to the present invention. Detailed Implementation

[0038] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0039] This invention provides three embodiments of a device for preparing three-dimensional microstructures using microscopic projection, which can be used for photopolymerization printing of three-dimensional microstructures, as detailed below:

[0040] [1] An embodiment of a device for preparing three-dimensional microstructures using microscopic projection 1

[0041] The following is a reference appendix Figure 1 To illustrate a first embodiment of the device proposed according to the present invention.

[0042] An apparatus for fabricating three-dimensional microstructures using microscopic projection includes a pattern generator 101, a pattern display 102, a projection light source 103, a collimating lens 104, an imaging lens 105, a microscope objective 106, a sample substrate 107, and a Z-axis motion platform 108. The pattern display 102, the projection light source 103, the collimating lens 104, the imaging lens 105, and the microscope objective 106 form an optical system. In this embodiment, the sample substrate 107 is connected to the Z-axis motion platform 108 via a connecting device 110. The Z-axis movement of the Z-axis motion platform 108 moves the sample substrate 107 away from or towards the microscope objective 106. The relative distance between the microscope objective 106, the imaging lens 105, and the pattern display 102 remains constant. In this embodiment, the overall magnification of the optical system is a fixed value.

[0043] The pattern generator 101 generates a specific pattern, which exists in the form of a grayscale image; the pattern display 102 is used to display the grayscale image generated by the pattern generator 101; the projection light source 103 is used to generate divergent light of a specific wavelength, and the collimating lens 104 collimates the divergent light into projection light; the imaging lens 105 generates an intermediate image of the pattern displayed on the pattern display 102 between the imaging lens 105 and the microscope objective 106; the microscope objective 105 displays the intermediate image in miniaturized form on its object-side focal plane; the sample substrate 107 is used to support the prepared three-dimensional microstructure; the Z-axis motion platform 108 is used to change the relative distance between the sample substrate 107 and the microscope objective 105.

[0044] The pattern display 102 is located at the image-side focal plane of the imaging lens 105; the grayscale value of the grayscale image is positively correlated with the transmittance of the display unit of the pattern display 102, and the higher the grayscale value, the greater the transmittance; the pattern on the pattern display 102 has a high grayscale value, allowing the projection light to pass through; the background grayscale value of the pattern is 0, which is used to block the parallel projection light; the pattern on the pattern display 102 is an enlarged version of the current cross-sectional pattern of the prepared three-dimensional microstructure, and the magnification is equal to the overall magnification of the optical system.

[0045] The divergent light of a specific wavelength generated by the projection light source 103 is collimated by the collimating lens 104 and then passes sequentially through the pattern display 102, the imaging lens 105, and the microscope objective 106, generating a miniature pattern on the object-side focal plane of the microscope objective 106; the liquid photocurable material 109 at the object-side focal plane of the microscope objective 106 is solidified and formed in the form of the miniature pattern.

[0046] The pattern display 102 is a monochrome liquid crystal display, and the size of a single liquid crystal cell is less than 100 micrometers.

[0047] The microscope objective 106 is a plan objective, preferably an optical infinity plan apochromatic objective.

[0048] The sample substrate 107 is made of a metal material or metal alloy with excellent elasticity and has a microstructure array on its surface; the microstructure array is composed of microstructure units with a feature width of less than 500 micrometers and a feature height of less than 100 micrometers; the preferred metal material is manganese or spring steel, and the preferred metal alloy is beryllium copper alloy.

[0049] [2] Example 2 of a device for preparing three-dimensional microstructures using microscopic projection

[0050] The following is a reference appendix Figure 2 To illustrate a variation of the device proposed according to the present invention.

[0051] An apparatus for fabricating three-dimensional microstructures using microscopic projection includes a pattern generator 101, a pattern display 102, a projection light source 103, a collimating lens 104, an imaging lens 105, a microscope objective 106, a sample substrate 107, and a Z-axis motion platform 108. The pattern display 102, the projection light source 103, the collimating lens 104, the imaging lens 105, and the microscope objective 106 constitute an optical system. In this variation, the microscope objective 106 is connected to the Z-axis motion platform 108 via a connector 110. The sample substrate 107 remains stationary, and the microscope objective 106 moves closer to or away from the sample substrate 107 by the Z-axis movement of the Z-axis motion platform 108. In this variation, the relative distance between the microscope objective 106 and the imaging lens 105 changes when the Z-axis motion platform 108 moves. In this variation, the overall magnification of the optical system changes due to the movement of the Z-axis motion platform 108.

[0052] [3] Example 3 of a device for preparing three-dimensional microstructures using microscopic projection

[0053] The following is a reference appendix Figure 3 To illustrate another variation of the device proposed according to the present invention.

[0054] An apparatus for fabricating three-dimensional microstructures using microscopic projection includes a pattern generator 101, a pattern display 102, a projection light source 103, a collimating lens 104, an imaging lens 105, a microscope objective 106, a sample substrate 107, and a Z-axis motion platform 108. The pattern display 102, the projection light source 103, the collimating lens 104, the imaging lens 105, and the microscope objective 106 form an optical system. In this modified example, the pattern display 102, the projection light source 103, the collimating lens 104, the imaging lens 105, and the microscope objective 106 are assembled as a single unit, with their relative positions remaining unchanged, and are connected to the Z-axis motion platform 108 via a connecting device 110. The sample substrate 107 is fixed, and the optical system moves closer to or away from the sample substrate 107 by the Z-axis movement of the Z-axis motion platform 108. In this embodiment, the overall magnification of the optical system is a fixed value.

[0055] See attached reference. Figure 4 As shown, embodiments of the present invention relate to a method for preparing three-dimensional microstructures using microscopic projection, relying on the aforementioned apparatus for preparing three-dimensional microstructures using microscopic projection, specifically including the following steps:

[0056] Step 1: Initialize the position of the Z-axis motion platform 108 so that the bearing surface of the sample substrate 107 is located at the image-side focal plane of the microscope objective 106.

[0057] Step 2: Add liquid photocurable material 109 so that the bearing surface of the sample substrate 107 is immersed in the liquid photocurable material 109;

[0058] Step 3: Load the design model of the three-dimensional microstructure and determine its reference direction, step distance, movement speed, light intensity, light exposure time and other fabrication process parameters;

[0059] Step 4, as attached Figure 5 As shown, taking the reference direction as the normal, the minimum projection position of the three-dimensional microstructure 301 in the reference direction as the starting point, the maximum projection position of the three-dimensional microstructure 301 in the reference direction as the ending point, and the set step distance as the reference, the corresponding cutting surfaces 302 of the three-dimensional microstructure are generated at equal intervals, and the corresponding cutting surface pattern 303 is obtained.

[0060] Step 5: Turn on the projection light source 103 and set the entire pattern display 102 to grayscale value 0 to block the light emitted by the projection light source 103 from entering the imaging lens 105;

[0061] Step 6: Taking the current position of the Z-axis motion platform 108 as the starting position, the pattern generator 101 magnifies the cross-sectional pattern 303 of the three-dimensional microstructure corresponding to the starting position according to the overall magnification of the optical system and converts it into a grayscale image 304.

[0062] Step 7: The pattern generator 101 transmits and displays the grayscale image 304 corresponding to the current position on the pattern display 102. The projection light source 103 emits light of a specific wavelength at the illumination intensity set in step 3 and displays the corresponding grayscale image 304 at the image-side focal plane position of the microscope objective 106. The display duration of the grayscale image is the illumination time set in step 3.

[0063] Step 8: Set the pattern display 102 to the minimum grayscale value 0 to block the projection light from entering the imaging lens 105. Move the position of the Z-axis motion platform 108 to increase the distance between the microscope objective 106 and the sample substrate 107 by the step distance set in step 3. Extract the cross-sectional pattern corresponding to the current position and generate the corresponding grayscale image.

[0064] Step 9: Repeat steps 6-8 until the fabrication of the three-dimensional microstructure is complete;

[0065] Step 10: Turn off the projection light source 103.

[0066] In step 6 above, the specific method for converting the cross-sectional pattern 303 into a grayscale image 304 is as follows: (see attached image) Figure 6 As shown, the cross-sectional pattern is drawn by scanning from left to right using horizontal scan lines 305, with the initial number of intersection points set to 0. Each time the horizontal scan line intersects the boundary of the cross-sectional pattern, the number of intersection points is incremented by 1. When the number of intersection points at the current horizontal position is odd, that position is a filled area; when the number of intersection points at the current horizontal position is even, that position is a non-filled area. The grayscale value of the filled area is set to the maximum grayscale value, and the grayscale value of the non-filled area is set to the minimum grayscale value of 0. Following the above process, filling and assignment are completed from top to bottom to generate the grayscale image.

[0067] This invention also relates to a three-dimensional microstructure photopolymerization printer based on microscopic projection, comprising the aforementioned apparatus for preparing three-dimensional microstructures using microscopic projection, and printing the three-dimensional microstructures using the aforementioned method for preparing three-dimensional microstructures using microscopic projection. This invention provides two embodiments of a three-dimensional microstructure photopolymerization printer based on microscopic projection.

[0068] [1] Example 1 of a three-dimensional microstructure photopolymerization printer based on microscopic projection

[0069] See attached reference. Figure 7 As shown, a three-dimensional microstructure photopolymerization printer based on microscopic projection includes a device for preparing three-dimensional microstructures using microscopic projection, a liquid level control module, a container module, a beam splitter 401, an observation camera 402, a reflector 403, an XY dual-axis motion platform 404, a base 411, a light source driver 412, and a motion driver 413.

[0070] The device for preparing three-dimensional microstructures using microscopic projection described in this embodiment adopts the structure provided in the first embodiment, including a pattern generator 101, a pattern display 102, a projection light source 103, a collimating lens 104, an imaging lens 105, a microscope objective lens 106, a sample substrate 107, and a Z-axis motion platform 108.

[0071] The container module consists of a container 405, a container fixing plate 409, a clamp, and an adapter 410. The container 405 is used to hold the liquid photocurable material 109, and the sample substrate 107 is completely immersed in the liquid photocurable material 109. The microscope objective 106 is located above the sample substrate 107. After being fixed and transferred by the clamp and adapter 410, the container 405 is fixed together with the base 411.

[0072] The Z-axis motion platform 108 is mounted with a transition device 110 on its motion side; the transition device 110 has an L-shaped plate, and the sample substrate 107 is fixed on the horizontal plate of the L-shaped plate.

[0073] The liquid level control module includes a vertical adjustment plate 407 and a Z-axis adjustment motion platform 406. The vertical adjustment plate 407 is installed on the moving side of the Z-axis adjustment motion platform 406, and its cross-sectional area is the same as that of the vertical portion of the L-shaped plate. When fabricating a three-dimensional microstructure, the Z-axis motion platform 108 moves downward along the Z-axis, while the Z-axis adjustment motion platform 406 moves upward along the Z-axis. The movement speed and movement distance are the same, ensuring that the liquid surface position of the liquid photocurable material 109 remains unchanged.

[0074] The aforementioned three-dimensional microstructure photopolymerization printer based on microscopic projection includes a pattern display 102 that is a liquid crystal display, with a beam splitter 401 installed between it and the imaging lens 105. The beam splitter 401 is a 45-degree angle beam splitter. Using the beam splitting surface of the beam splitter 401 as a reference, the imaging target surface 402-1 of the observation camera 402 is placed at the conjugate position of the pattern display 102, and is used to observe the curing process of the cross-sectional pattern 303 of the projected three-dimensional microstructure 301.

[0075] The aforementioned three-dimensional microstructure photopolymerization printer based on microscopic projection has its Z-axis motion platform 108 mounted on an XY dual-axis motion platform 404, which can drive the sample substrate to move in the XYZ three-dimensional space; the XY dual-axis motion platform 404 is mounted on a base 411.

[0076] In this embodiment, the pattern generator 101 is a general-purpose computer, connected to the pattern display 102 via a video data cable; the projection light source 103 is connected to the light source driver 412, and the light source driver 412 is connected to the pattern generator 101; the pattern generator 101 is connected to the light source driver 412 via a signal line and issues on / off commands and brightness control commands to it; the Z-axis motion platform 108, the XY dual-axis motion platform 404, and the Z-axis adjustable motion platform 406 are connected to the motion driver 413, and the motion driver 413 is connected to the pattern generator 101 via a signal line; the pattern generator 101 issues motion commands to the motion driver 413 to control the movement of each moving component, realizing the planar movement of the XY dual-axis motion platform 404, thereby enabling the splicing and printing of large-area microstructures.

[0077] [2] Example 2 of a three-dimensional microstructure photopolymerization printer based on microscopic projection

[0078] See attached reference. Figure 8 As shown, another modified embodiment of a three-dimensional microstructure photopolymerization printer based on microscopic projection includes a device for preparing three-dimensional microstructures using microscopic projection, a container module, a beam splitter 401, an observation camera 402, a reflector 403, an XY dual-axis motion platform 404, a base 411, a light source driver 412, and a motion driver 413.

[0079] One difference between this embodiment and Embodiment 1 is that the optical system in the apparatus for preparing three-dimensional microstructures using microscopic projection is inverted, meaning that the microscope objective 106 is below the sample substrate 107. The container 405 is made of a highly transparent material, and the projected light shines through the bottom plate of the container 405 onto the corresponding position of the liquid photocurable material 109.

[0080] Another difference between this embodiment and Embodiment 1 is that the liquid level control module in Embodiment 1 is not required. When fabricating three-dimensional microstructures, the Z-axis motion platform 108 moves upward along the Z-axis. This embodiment requires the microscope objective 106 to have a large working distance.

[0081] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all technical solutions obtained through equivalent substitution or transformation fall within the protection scope of the present invention.

Claims

1. A method for fabricating a three-dimensional microstructure using microprojection, characterized by An apparatus for preparing three-dimensional microstructure by micro-projection is adopted, which comprises a pattern generator (101), a pattern display (102), a projection light source (103), a collimating lens (104), a converging lens (105), a micro objective (106), a sample substrate (107) and a Z-axis motion platform (108); the pattern display (102), the projection light source (103), the collimating lens (104), the converging lens (105) and the micro objective (106) constitute an optical system; Specifically comprising the following steps: Step 1, initializing the position of the Z-axis motion platform, so that the bearing surface of the sample substrate is located at the image-side focal plane position of the micro objective; Step 2, filling the liquid light-cured material, so that the bearing surface of the sample substrate is immersed in the liquid light-cured material; Step 3, loading the design model of the three-dimensional microstructure, determining the reference direction, the step distance, the motion speed, the light intensity and the light time; Step 4, taking the reference direction as the normal line, taking the minimum projection position of the three-dimensional microstructure in the reference direction as the starting point, taking the maximum projection position of the three-dimensional microstructure in the reference direction as the end point, taking the set step distance as the reference, generating the cross-sections of the three-dimensional microstructure at the corresponding positions at equal intervals, and obtaining the corresponding cross-section patterns; Step 5, turning on the projection light source, and setting the pattern display as the gray scale value 0 as a whole to block the light emitted by the projection light source from entering the converging lens; Step 6, taking the current position of the Z-axis motion platform as the starting position, the pattern generator magnifies and converts the cross-section pattern corresponding to the starting position into a gray scale image according to the overall magnification of the optical system; Step 7, the pattern generator transmits and displays the gray scale image corresponding to the current position on the pattern display, the projection light source emits light of a specific wavelength at the light intensity set in step 3, and displays the corresponding gray scale image at the image-side focal plane position of the micro objective, and the display time of the gray scale image is the light time set in step 3; Step 8, setting the pattern display as the minimum gray scale value 0 as a whole to block the projection light from entering the converging lens, moving the position of the Z-axis motion platform so that the distance between the micro objective and the sample substrate increases by the step distance set in step 3, extracting the cross-section corresponding to the current position, and generating a gray scale image; Step 9, repeating steps 6-8 until the preparation of the three-dimensional microstructure is completed; Step 10, turning off the projection light source.

2. The method for preparing a three-dimensional microstructure using microprojection according to claim 1, wherein The pattern generator (101) generates a specific pattern in the form of a gray scale image; the pattern display (102) is used to display the gray scale image generated by the pattern generator (101); the projection light source (103) is used to generate divergent light of a specific wavelength, the collimating lens (104) collimates the divergent light into projection light; the image-forming lens (105) generates an intermediate image of the pattern displayed on the pattern display (102) between the image-forming lens (105) and the microscope objective (106); the microscope objective (106) microscopically displays the intermediate image on its object-side focal plane; the sample substrate (107) is used to carry the prepared three-dimensional microstructure; the Z-axis motion platform (108) is used to change the relative distance between the sample substrate (107) and the microscope objective (106).

3. The method for preparing a three-dimensional microstructure using microprojection according to claim 2, wherein The pattern display (102) is located at the image-side focal plane position of the image-forming lens (105); the gray scale value of the gray scale image is positively correlated with the light transmittance of the display unit of the pattern display (102), the higher the gray scale value, the greater the light transmittance; the pattern on the pattern display (102) has a high gray scale value, allowing the projection light to pass through; the background gray scale value of the pattern is 0, used to block the parallel projection light; the pattern on the pattern display (102) is a magnified version of the current cross-sectional pattern of the prepared three-dimensional microstructure, and the magnification is equal to the overall magnification of the optical system.

4. The method for preparing a three-dimensional microstructure using microprojection according to claim 3, wherein The divergent light of a specific wavelength generated by the projection light source (103) is collimated by the collimating lens (104), and then passes through the pattern display (102), the image-forming lens (105) and the microscope objective (106) in turn, and generates a micro-pattern on the object-side focal plane of the microscope objective (106); the liquid photocuring material (109) at the object-side focal plane position of the microscope objective (106) is cured and shaped in the form of the micro-pattern.

5. The method for preparing a three-dimensional microstructure using microprojection according to claim 3, wherein The sample substrate (107) is connected to the Z-axis motion platform (108) through the adapter (110), and the Z-axis motion platform (108) moves the sample substrate (107) away from or close to the microscope objective (106); the relative distance between the microscope objective (106) and the image-forming lens (105), the pattern display (102) is fixed and unchanged.

6. The method for preparing a three-dimensional microstructure using microprojection according to claim 3, wherein The microscope objective (106) is connected to the Z-axis motion platform (108) through the adapter (110); the sample substrate (107) is fixed and immovable, and the Z-axis motion platform (108) moves the microscope objective (106) away from or close to the sample substrate (107); when the Z-axis motion platform (108) moves, the relative distance between the microscope objective (106) and the image-forming lens (105) changes; the overall magnification of the optical system changes due to the movement of the Z-axis motion platform (108).

7. The method for preparing a three-dimensional microstructure using microprojection according to claim 3, wherein The pattern display (102), the projection light source (103), the collimating lens (104), the imaging lens (105) and the microscope objective (106) are assembled into an integral whole, and are connected through the adapter (110) and the Z-axis motion platform (108); the sample substrate (107) is fixed, and the optical system is driven away from or close to the sample substrate (107) through the Z-direction movement of the Z-axis motion platform (108); the overall magnification of the optical system is a fixed value.

8. The method for preparing a three-dimensional microstructure using microprojection according to claim 5 or 6 or 7, characterized in that The sample substrate is made of a metal material with excellent elasticity, and has a microstructure array on the surface; the microstructure array is composed of microstructure units with a feature width less than 500 microns and a feature height less than 100 microns.

9. The method for preparing a three-dimensional microstructure using microprojection according to claim 1, wherein In step 6, the specific method for converting the sectioned surface pattern into a gray scale image is as follows: draw the sectioned surface pattern, scan from left to right through a horizontal scanning line, and set the initial number of intersection points as 0; when the horizontal scanning line intersects with the boundary of the sectioned surface pattern once, the number of intersection points is increased by 1; when the number of intersection points at the current horizontal position is odd, the position is a filling area; when the number of intersection points at the current horizontal position is even, the position is a non-filling area; the gray scale value of the filling area is set as the maximum gray scale value, and the gray scale value of the non-filling area is set as the minimum gray scale value 0; according to the above process, the filling and assignment are completed from top to bottom to generate the gray scale image.

10. A light-curing printer for producing a three-dimensional microstructure using microprojection, characterized by The device comprises a pattern generator (101), a pattern display (102), a projection light source (103), a collimating lens (104), an imaging lens (105), a microscope objective (106), a sample substrate (107), a Z-axis motion platform (108), a liquid level control module, a container module, a beam splitter (401), an observation camera (402), a mirror (403), an X-Y dual-axis motion platform (404), a base (411), a light source driver (412) and a motion driver (413); The device comprises a pattern generator (101), a pattern display (102), a projection light source (103), a collimating lens (104), an imaging lens (105), a microscope objective (106), a sample substrate (107), a Z-axis motion platform (108); The container module is composed of a container (405), a container fixing plate (409), a clamp and an adapter (410); the container (405) is used for loading a liquid photocuring material (109), the sample substrate (107) is entirely immersed in the liquid photocuring material (109), and the microscope objective (106) is above the sample substrate (107); after the container (405) is fixed and adapted through the clamp and the adapter (410), the container (405) is fixed with the base (411) together; The motion side of the Z-axis motion platform (108) is provided with an adapter (110); the adapter (110) has an L-shaped plate, and the sample substrate (107) is fixed on the horizontal plate of the L-shaped plate; The motion side of the Z-axis motion platform (108) is provided with an adapter (110); the adapter (110) has an L-shaped plate, and the sample substrate (107) is fixed on the horizontal plate of the L-shaped plate; The liquid level control module comprises a vertical adjusting plate (407) and a Z-axis adjusting motion platform (406); the vertical adjusting plate (407) is installed on the motion side of the Z-axis adjusting motion platform (406), and the cross-sectional area thereof is the same as that of the vertical part of the L-shaped plate; when preparing a three-dimensional microstructure, the Z-axis motion platform (108) moves downward along the Z-axis, and the Z-axis adjusting motion platform (406) moves upward along the Z-axis at the same speed and distance, so as to ensure that the liquid level position of the liquid photocuring material (109) is unchanged; The pattern display (102) adopts a liquid crystal display, which is provided with a beam splitter (401) between the pattern display (102) and the imaging lens (105); the beam splitter (401) is a 45-degree beam splitter; an imaging target surface (402-1) of an observation camera (402) is placed at the conjugate position of the pattern display (102) based on the splitting surface of the beam splitter (401), and is used to observe the curing process of the sectioned surface pattern (303) of the projected three-dimensional microstructure (301); The Z-axis motion platform (108) is integrally installed on an X-Y dual-axis motion platform (404), and can drive the sample substrate to move in an X-Y-Z three-dimensional space; the X-Y dual-axis motion platform (404) is installed on a base (411).

11. The light-cured printer for preparing a three-dimensional microstructure using micro-projection according to claim 10, wherein The pattern generator (101) is a general-purpose computer, which is connected with the pattern display (102) through a video data line; the projection light source (103) is connected with a light source driver (412), and the light source driver (412) is connected with the pattern generator (101); the pattern generator (101) is connected with the light source driver (412) through a signal line, and sends opening and closing instructions and brightness control instructions to the light source driver (412); the Z-axis motion platform (108), the X-Y dual-axis motion platform (404) and the Z-axis adjusting motion platform (406) are connected with a motion driver (413), and the motion driver (413) is connected with the pattern generator (101) through a signal line; the pattern generator (101) sends motion instructions to the motion driver (413) to control the motion of each motion component, so as to realize the planar motion of the X-Y dual-axis motion platform (404), and then the splicing printing of a large-area microstructure can be realized.

12. A light-curing printer for producing a three-dimensional microstructure using microprojection, characterized by The device for preparing a three-dimensional microstructure by micro-projection further comprises a container module, a beam splitter (401), an observation camera (402), a reflector (403), an X-Y dual-axis motion platform (404), a base (411), a light source driver (412) and a motion driver (413); The other device for preparing three-dimensional microstructure by micro-projection comprises a pattern generator (101), a pattern display (102), a projection light source (103), a collimating lens (104), a converging lens (105), a microscope objective (106), a sample substrate (107), and a Z-axis motion platform (108). The optical system in the device adopts an inverted mode, i.e. the microscope objective (106) is below the sample substrate (107); The container module is composed of a container (405), a container fixing plate (409), a clamp and an adapter device (410). The container (405) is used for loading liquid photocuring material (109), and the sample substrate (107) is wholly immersed in the liquid photocuring material (109). After being fixed and adapted by the clamp and the adapter device (410), the container (405) is fixed with the base (411); The motion side of the Z-axis motion platform (108) is installed with an adapter device (110). The adapter device (110) has an L-shaped plate, and the sample substrate (107) is fixed on the horizontal plate of the L-shaped plate; The pattern display (102) adopts a liquid crystal display, which is installed with a beam splitter (401) between the pattern display (102) and the converging lens (105). The beam splitter (401) is a 45-degree beam splitter. An imaging target surface (402-1) of an observation camera (402) is placed at the conjugate position of the pattern display (102) based on the splitting surface of the beam splitter (401), and is used to observe the curing process of the sectioned surface pattern (303) of the projected three-dimensional microstructure (301); The Z-axis motion platform (108) is wholly installed on an X-Y dual-axis motion platform (404), which can drive the sample substrate to move in the X-Y-Z three-dimensional space. The X-Y dual-axis motion platform (404) is installed on the base (411); The container (405) is made of high-transparency material. The projection light is irradiated to the corresponding position of the liquid photocuring material (109) through the bottom plate of the container (405). When the three-dimensional microstructure is prepared, the Z-axis motion platform (108) moves upward along the Z-axis.

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