Method and device for manufacturing neutron absorption grating through particle filling

Abstract

The invention discloses a method and a device for manufacturing a neutron absorption grating through particle filling, and relates to the technical field of processing. According to the method, filling is carried out by adopting a segmented filling method, and each grating channel is divided into n sections of areas to be filled along the length direction of the grating; each section of filling area is provided with a grating inlet and a grating outlet; wherein each grating channel comprises a plurality of sections of filling areas. According to the invention, segmented filling is carried out on each grating channel, so that the large-size filling pressure drop is reduced, and the manufacturing efficiency is improved.

Description

Technical Field

[0001] The invention relates to the field of processing technology, and in particular to a method and device for making a neutron absorption grating by filling particles. Background Art

[0002] Neutron grating phase contrast imaging technology based on neutron grating interferometer can non-destructively detect the internal structure information of samples and increase the contrast between materials with similar absorption levels. It is widely used in energy, materials, archaeology and other fields. The grating is the most basic and critical optical element in the neutron grating interferometer, and the parameters of the grating are closely related to the performance of the grating interferometer. With the increasing demand for detecting the internal microstructure information of samples in a larger imaging field of view, higher requirements are placed on the period and aspect ratio of the neutron grating. The current main challenge is to produce neutron absorption gratings with large size, small period and large aspect ratio.

[0003] Since gadolinium has a high absorption cross section for neutrons, many methods for making neutron absorption gratings based on gadolinium or gadolinium oxides have been developed. The particle filling method is one of the most promising methods for making large-size neutron absorption gratings that meet imaging requirements. It is usually implemented by free particle deposition to fill the grating. This method has the advantages of simple process and easy implementation. Its principle is to use the gravity of the particle solution to fill the particles from outside the grating groove to inside the grating groove. It is suitable for the production of low aspect ratio absorption gratings. However, as the aspect ratio of the grating structure increases, due to the obstruction of the sidewall, the filling rate and uniformity of the particles will be low when the grating is filled by gravity deposition. In addition, when developing small-period absorption gratings, it is necessary to select particles of tens to hundreds of nanometers for filling. The gravity deposition effect of the particles is weakened, and Brownian motion dominates, resulting in a low filling rate and poor uniformity of the particles. The pressurized particle filling method based on particle deposition can increase the particle filling rate in the grating groove by pressurization, and use the adaptive deformation of the pressurized material to improve the uniformity of the particle-filled grating. It is suitable for the production of low aspect ratio absorption gratings. However, as the aspect ratio of the grating structure increases, the sidewalls significantly hinder the particle filling grating, and the effectiveness of pressurized particle filling decreases. Currently, the neutron absorption grating made by the existing particle filling method cannot meet the requirements of neutron grating interferometers. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a method for making a neutron absorption grating by particle filling. The method adopts segmented filling to fill each grating channel in segments, thereby reducing the large-size filling pressure drop and improving the manufacturing efficiency.

[0005] Correspondingly, the present invention also provides a device for making a neutron absorption grating by filling particles. The device is based on the principle of the same pressure drop in parallel channels, and parallel microfluidic pipes are designed outside the grating. Liquid pressure is used to drive the particle solution to fill the grating channel and make the particles densely stacked in the channel, thereby improving the uniformity and filling rate of the grating made by the particle filling method.

[0006] In order to achieve the above object, the present invention adopts the following technical scheme:

[0007] A method for making a neutron absorption grating by particle filling, characterized in that a segmented filling method is used for filling, and each grating channel is divided into n sections of areas to be filled along the length direction of the grating; each section of the filling area is provided with a grating entrance and a grating exit; wherein each grating channel includes multiple sections of filling areas.

[0008] The number n of the areas to be filled is calculated by the following formula:

[0009] ;

[0010] Where μ is the liquid viscosity, e is the particle stacking porosity, is the solution flow rate in each grating channel, L is the total grating length, is the system sealing pressure, is the particle size used for filling.

[0011] The method further comprises the step of setting a filter membrane, at least setting a filter membrane at the grating outlet.

[0012] Wherein, a microfluidic pipeline is used as a circulation pipeline for the particle solution; the particle solution flows out from the outlet pipe of the inlet pipe group of the flow microfluidic pipeline and enters the grating inlet; the number of outlet pipes of the inlet pipe group of the microfluidic pipeline is n / 2.

[0013] The m value of the flow pipe inlet of each outlet pipe is determined according to the following formula:

[0014] ;

[0015] in, is the Poiseuille number, which is related to the geometry of the channel. The particle solution flowing through the branch is the flow rate in the microchannel; W is the total width of the grating, is the particle size used for filling, e is the particle packing porosity, is the hydraulic diameter of the microchannel, is the solution flow rate in each grating channel, = L / n, where L is the total length of the grating.

[0016] Wherein, the number of branches of the flow channel of the microfluidic channel is mn / 2.

[0017] The method specifically comprises the following steps:

[0018] Design and process microfluidic pipelines and filter membranes respectively;

[0019] Assemble and seal the grating, filter membrane and microfluidic channel;

[0020] Flushing the grating, filter membrane and microfluidic pipeline;

[0021] The particle solution is injected from the inlet of the microfluidic channel until the inlet of the grating channel of the grating is completely blocked.

[0022] Wherein, the assembly process is carried out in a full water environment.

[0023] A device for making a neutron absorption grating by filling particles comprises a grating, a microfluidic pipeline and a filter membrane. The microfluidic pipeline is connected to the inlet and outlet of the grating channel of the grating, and the filter membrane at least covers the outlet position of the grating channel of the grating; the part of the filter membrane that coincides with the grating inlet position is hollowed out.

[0024] The number of solution inlets in each grating channel is n.

[0025] Wherein, the microfluidic pipeline is made of soft material.

[0026] The beneficial effects of the present invention are as follows:

[0027] (1) The present invention adopts segmented filling to perform segmented filling on each grating channel, thereby reducing the large-size filling pressure drop and improving the manufacturing efficiency.

[0028] (2) The present invention is based on the principle of parallel channel flow distribution. When different grating channels have different flow resistances due to uneven accumulation of particles, the particle solution can be adaptively distributed to different grating channels to achieve uniform filling, which can significantly improve the uniformity of particle filling in making neutron absorption gratings.

[0029] (3) The present invention is applicable to the production of neutron absorption gratings of different sizes, and is not limited by the grating period and aspect ratio. Soft materials with microfluidic channels of corresponding sizes can be designed according to the grating size, so as to ensure that the particle solution is evenly distributed at different positions of the grating.

[0030] (4) Compared with the existing particle gravity sedimentation filling method, the present invention can improve the particle filling rate.

[0031] (5) Most of the particle solution injected in the present invention is used to fill the grating. Compared with the existing particle gravity deposition filling method, the particle solution is more fully utilized.

[0032] (6) The present invention is not limited by the type of particles. An X-ray absorption grating can be prepared by selecting particles with high X-ray absorption, such as tungsten particles, bismuth particles, etc., to fill the grating. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 An overall schematic diagram of an embodiment of a method for making a neutron absorption grating for particle filling of the present invention;

[0034] Figure 2 A schematic diagram of the assembly of a device for making a neutron absorption grating for particle filling of the present invention;

[0035] Figure 3 A schematic diagram of the fabrication of a microfluidic pipeline of a device for fabricating a neutron absorption grating by filling particles of the present invention;

[0036] Figure 4 This is a cross-sectional view of the prepared neutron absorption grating.

[0037] Wherein, the reference numerals are: 100 - grating, 200 - microfluidic channel, 300 - filter membrane. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] A method for making a neutron absorption grating by particle filling adopts a segmented filling method to fill, and each grating channel is divided into n sections of areas to be filled along the length direction of the grating; each section of the filling area is provided with a grating entrance and a grating exit; wherein each grating channel includes multiple sections of filling areas.

[0040] See also Figure 1, the total length of the grating is L, and the width is W. In order to reduce the filling pressure drop of the large-size grating and improve the manufacturing efficiency, the grating can be divided into n segments along the length direction of the grating, each segment has a grating entrance position and an exit position, and the length of each segment is l=L / n. That is to say, the present invention divides each grating channel into n areas to be filled, and sets a grating entrance and a grating exit in each area to be filled, thereby realizing segmented filling. Generally speaking, the larger n is, the smaller the filling pressure drop of each area to be filled, and the more uniform the filling is, thereby achieving uniform filling of the entire grating and improving the filling rate.

[0041] In one embodiment, the number n of the areas to be filled is calculated by the following formula:

[0042] ; (1)

[0043] Where μ is the liquid viscosity, e is the particle stacking porosity, is the solution flow rate in each grating channel, L is the total length of the grating, P 0 is the system sealing pressure, is the particle size used for filling.

[0044] The design ideas are as follows:

[0045] The liquid viscosity is μ, the particle stacking porosity is e; the solution flow rate in each grating channel is , the length of each segment filling is l, and the particle size used for filling is After filling, the flow pressure drop can be approximately calculated by the following formula:

[0046] (2)

[0047] Assume the system sealing pressure is P 0 , it is necessary to ensure that the filling process system is sealed P 0 >ΔP, thus formula (1) is derived.

[0048] Preferably, the method further comprises the step of arranging a filter membrane, at least at the grating outlet, so as to allow the solution to flow out while the particles are retained and accumulated in the grating channel.

[0049] Preferably, a microfluidic pipeline is used as a flow pipeline for the particle solution; the particle solution flows out from the outlet pipe of the inlet pipe group of the microfluidic pipeline and enters the grating inlet; the number of outlet pipes of the inlet pipe group of the microfluidic pipeline is n / 2. Since the injected particle solution can flow to both sides of the grating to complete the two-segment filling area, the number of outlet pipes of the inlet pipe group of the microfluidic pipeline only needs to be n / 2.

[0050] More preferably, the flow channel inlet m value of the outlet pipe of the inlet pipe group of each microfluidic channel is determined according to the following formula:

[0051] ;

[0052] in, is the Poiseuille number, The particle solution flowing through the branch has a flow rate in the microchannel, W is the total width of the grating, is the particle size used for filling, e is the particle packing porosity, is the hydraulic diameter of the microchannel, is the solution flow rate in each grating channel, = L / n, where L is the total length of the grating.

[0053] In order to ensure that the entrance and exit pressures of the grating channels at different positions of the entire grating are basically the same and form parallel channels, the external microfluidic pipeline is designed using the dichotomy method to connect the entrance positions of all grating channels. Assume that m microchannel branch entrances are set along the grating width direction (W) at each entrance position, and the length of the particle solution injected from the branch entrance with the maximum pressure drop along the grating width direction is l 1 =W / (2m), the corresponding flow pressure drop can be approximately calculated by the following formula:

[0054] (3)

[0055] in, is the Poiseuille number, μ is the viscosity of the liquid, is the flow rate of the particle solution flowing through the branch in the microchannel, is the hydraulic diameter of the microchannel.

[0056] In order to improve the uniformity of particle filling of large-size gratings by utilizing the property of the same pressure drop in parallel channels, it is necessary to ensure that the pressure drop difference of the particle solution flowing to different inlet positions of the grating needs to be much smaller than the pressure drop when the particles fill the grating, that is, , then the value range of m is as follows:

[0057] (4)

[0058] The bisection method and the parallel pipeline flow distribution principle are used to finally divide the microfluidic pipeline into mn / 2 branches, so that the particle solution injected into the total inlet of the microfluidic pipeline is distributed at each branch in a ratio of approximately 1:1, and finally the particle solution flow rate of each branch directly in contact with the grating inlet is the same. The design principle of the outlet channel is consistent with that of the inlet channel.

[0059] Specifically, the method for making a neutron absorption grating by particle filling of the present invention comprises the following steps:

[0060] Design and process microfluidic channels according to grating size, system sealing pressure and flow resistance after particle accumulation; obtain channel brackets through photolithography or 3D printing technology, and then use soft materials to mold and demold to make soft materials with microfluidic channels;

[0061] According to the grating channel parameters, the corresponding particle size and filter membrane are selected, and the filter membrane is processed; according to the grating channel parameters, the appropriate particle size and particle filter membrane are selected, and the filter membrane is processed according to the inlet position and the grating size;

[0062] See also Figure 2 , assemble and seal the grating, filter membrane and microfluidic pipeline; assemble the grating, filter membrane and microfluidic pipeline and apply pressure on the top to keep the system sealed; the sealing pressure of the device can be detected by injecting solution at a high flow rate; the purpose of sealing is to allow the injected particle solution to flow from the grating inlet to the outlet as designed, otherwise the injected particle solution will leak to the outside of the grating; as the particles are gradually filled, the fluid resistance increases. In order to keep the flow rate constant, the injection pump pressure increases, and the particle solution pressure at the inlet also increases. The sealing pressure is required to be greater than the liquid pressure when the final filling is completed, and the system will not leak. The sealing pressure can be calculated and set according to actual needs.

[0063] The grating, filter membrane and microfluidic pipeline are flushed; under the condition of device sealing, a solution that is easy to infiltrate the channel is injected from the channel inlet for a long time and at a high flow rate to flush the channel, ensuring that the gas in the inlet channel, the grating channel and the outlet channel is fully discharged;

[0064] Inject the particle solution from the inlet of the microfluidic pipeline until the inlet of the grating channel of the grating is completely blocked. In this step, a constant flow rate is used to inject excess particle solution. The specific flow rate value should be selected based on the fluid resistance of the grating channel after filling (including particle packing density, particle size and segmented filling length). Fluid resistance < sealing critical pressure. Prepare a particle solution with gadolinium or gadolinium oxide particles and particle carrier solution in a mass ratio (1:10 - 1:200), and use an ultrasonic machine to evenly disperse the particles in the solution. Inject the particle solution until the entrance of the grating channel is completely blocked by the particles, completing the grating filling.

[0065] Furthermore, the assembly process is carried out in a full water environment, and after assembly, the full water environment is removed and pressurized and sealed by a pressurizing device.

[0066] See also Figure 2A device for making a neutron absorption grating by filling particles, comprising a grating 100, a microfluidic channel 200 and a filter membrane 300, wherein the microfluidic channel 200 is connected to the inlet and outlet of the grating channel of the grating 100, and the filter membrane 300 at least covers the outlet position of the grating channel of the grating; the portion of the filter membrane that overlaps with the grating inlet position is hollow. The microfluidic channel is used for the circulation of particle solution.

[0067] A microfluidic channel for solution circulation corresponding to the grating size is designed and processed above the grating using the dichotomy method, so that all grating channels are in parallel.

[0068] Preferably, the number of solution inlets of each grating channel is n; the number of solution outlets of each grating channel is x=n.

[0069] Furthermore, the microfluidic conduit is made of soft material. The soft material may be PDMS. The purpose of selecting the soft material is that the soft material deforms after pressurization and is easy to seal.

[0070] At the entrance of the grating channel, according to the principle of minimum pressure drop of liquid circulation, the liquid pressure provided by the injection pump can drive the particle solution to be smoothly injected into the grating channel through the external microfluidic pipeline and circulate in the grating channel. At the outlet of the grating channel, a filter membrane is set for filtration to make the solution flow out, while the particles are retained and accumulated in the grating channel. Since most of the injected particle solution is used to fill the grating, the injected particles can be fully utilized. Based on the principle of the same pressure drop of parallel channels, the particle solution adaptively fills different grating channels according to the circulation resistance to achieve uniform filling of the grating with particles. In the process of continuous injection of the particle solution, the liquid pressure provided by the injection pump increases with the increase of the accumulation of particles in the channel. The particles are evenly and tightly accumulated under the action of the liquid pressure until the grating channel is filled, and finally the production of the neutron absorption grating is realized.

[0071] Embodiment 1:

[0072] A method for making a neutron absorption grating by particle filling, the specific steps are as follows:

[0073] Step 1, select a (110) crystal orientation silicon wafer, use AZ1500 photoresist to obtain a photoresist grating mask through UV exposure and development, and then obtain a silicon nitride grating mask through dry etching. Place it in a KOH solution with a mass fraction of 50%, and wet etch it in a 50°C water bath to finally obtain a silicon grating with a period of 4 microns, a duty cycle of 0.3, a depth of 56 microns, and an area of ​​60 mm × 60 mm.

[0074] Step 2: According to the sealing pressure of 0.6MPa, the particle size of 150nm, the particle packing density of 0.3, the total injection particle solution flow rate Q = 0.05ml / min, and the width and height of the upper microchannel are both 1mm, use formula (2) and formula (4) to calculate the values ​​of m and n. In the experiment, the values ​​of n and m are 16 and 4 respectively, that is, there are 8 parallel inlet tubes (particle solution inlet channels) above the grating, the corresponding inlet branches are 32 (each inlet tube has 4 branch inlets), and 9 parallel solution outlet channels. The inlet and outlet channel brackets are designed using the dichotomy method. See Figure 3 ABS material was used to obtain the inlet channel bracket and part of the outlet channel bracket by 3D printing, and part of the micro outlet channel of SU8 photoresist material was obtained by ultraviolet lithography technology, and the inlet and outlet channel brackets were positioned according to the design. A mixed solution with a ratio of PDMS to curing agent of 10:1 was prepared to mold the located inlet and outlet channel structure, and demolded after curing to obtain a microfluidic pipeline, that is, a PDMS soft material microfluidic pipeline integrating multiple inlet and outlet channels.

[0075] Step 3: Select gadolinium oxide particles with an average particle size of 150 nanometers and a filter membrane with a filtration pore size of 100 nanometers, and process an appropriate filter membrane according to the inlet position and grating size.

[0076] Step 4: In a full water environment, align and assemble the silicon grating, filter membrane, and microfluidic channel in sequence, and use a pressurizing device to apply a sealing pressure of 0.6 MPa on top. Inject a high-flow solution at the channel inlet to test the sealing state of the device.

[0077] Step 5: Inject ethanol solution from the inlet at a flow rate of 2 ml / min for 4 hours to exhaust.

[0078] Step 6: Prepare a particle solution with gadolinium oxide and ethanol at a ratio of 1:50, and use an ultrasonic machine to evenly disperse the particles in the solution. Then use a syringe pump to inject the particle solution at a flow rate of 0.05 ml per minute until the entrance of the grating channel is completely blocked by the particles, completing the grating filling.

[0079] See also Figure 4 , Figure 4 a in the figure is the cross-sectional diagram of the neutron absorption grating prepared by the natural particle deposition method. Figure 4 b in FIG. 1 is a cross-sectional view of the neutron absorption grating prepared in Example 1 of the present invention. Figure 4It can be seen that when the grating is filled by the natural particle deposition method, the average particle filling rate is less than 10% and the filling uniformity is poor. When the method of the present invention is used to fill the grating, the average particle filling rate can reach 30%, and the grating grooves at different positions can be filled with particles, and the particle filling rate and filling uniformity are significantly improved. Usually, the natural particle deposition to fill the grating requires the preparation of an excessive amount of particle solution, and only a small amount of solution can enter the grating groove for filling. Most of the particles are accumulated outside the grating groove, and the particle utilization rate is low. In this experiment, the prepared particle solution can be injected into the grating channel for stacking and filling, which effectively improves the utilization rate of the particle solution.

[0080] Embodiment 2:

[0081] A method for making a neutron absorption grating by particle filling, the specific steps are as follows:

[0082] Step 1, select a (110) crystal orientation silicon wafer, use AZ1500 photoresist to obtain a photoresist grating mask through UV exposure and development, and then obtain a silicon nitride grating mask through dry etching. Place it in a KOH solution with a mass fraction of 50%, and wet etch it in a 50°C water bath to finally obtain a silicon grating with a period of 40 microns, a duty cycle of 0.5, a depth of 230 microns, and an area of ​​60 mm × 60 mm.

[0083] Step 2: According to the sealing pressure of 0.6MPa, the particle size of 2 microns, the particle packing density of 0.4, the total injection particle solution flow rate Q = 0.2 ml per minute, and the width and height of the upper microchannel are both 1mm, the values ​​of m and n are calculated using formula (2) and formula (4). In the experiment, the values ​​of n and m are 8 and 4, respectively, that is, there are 4 parallel particle solution inlet channels above the grating, and the corresponding inlet branches have 16 and 5 parallel solution outlet channels. The inlet and outlet channel brackets are designed using the dichotomy method. The inlet channel and part of the outlet channel bracket are obtained by 3D printing using ABS material. The part of the micro outlet channel of SU8 photoresist material is obtained by ultraviolet lithography technology. The inlet and outlet channel brackets are positioned according to the design. A mixed solution with a PDMS and curing agent ratio of 10:1 is prepared to mold the positioned inlet and outlet channel structure, and demold after curing to obtain a microfluidic pipeline, that is, a PDMS soft material with multiple inlet and outlet channels.

[0084] Step 3: Select gadolinium oxide particles with an average particle size of 2 microns and a filter membrane with a filtration pore size less than 1 micron, and process an appropriate filter membrane based on the inlet position and grating size.

[0085] Step 4: In a full water environment, align and assemble the silicon grating, particle filter membrane, and microfluidic channel in sequence, and use a pressurizing device to apply a sealing pressure of 0.6 MPa on top. Inject a high-flow solution at the channel inlet to test the sealing state of the device.

[0086] Step 5: Inject ethanol solution from the inlet at a flow rate of 2 ml / min for 4 hours to exhaust.

[0087] Step 6: Prepare a particle solution with gadolinium oxide and ethanol at a ratio of 1:20, and use an ultrasonic machine to evenly disperse the particles in the solution. Then inject the particle solution at a flow rate of 0.2 ml per minute until the entrance of the grating channel is completely blocked by the particles, completing the grating filling.

[0088] When the grating is filled by natural particle deposition, the average particle filling rate is about 25% and the filling uniformity is poor. However, when this method is used to fill the grating, the average particle filling rate can reach 35%, and the grating grooves at different positions can be filled with particles, and the particle filling rate and filling uniformity are significantly improved. Usually, the natural particle deposition method to fill the grating requires the preparation of an excessive amount of particle solution, and only a small amount of solution can enter the grating groove for filling. Most of the particles are accumulated outside the grating groove, and the particle utilization rate is low. In this experiment, the prepared particle solution can be injected into the grating channel for stacking and filling, which effectively improves the utilization rate of the particle solution.

[0089] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0090] The parts not described in detail in the present description belong to the known technology in the art. The above embodiments are provided only for the purpose of describing the present invention, but not to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. Various equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method for making a neutron absorption grating by particle filling, characterized in that: The filling is performed by adopting a segmented filling method, where each grating channel is divided into n segments of areas to be filled along the length direction of the grating; each segment of the filling area is provided with a grating entrance and a grating exit; Each grating channel includes multiple filling areas.

2. The method for making a neutron absorption grating by particle filling according to claim 1, characterized in that: The number n of areas to be filled is calculated by the following formula: ； Where μ is the liquid viscosity, e is the particle stacking porosity, is the solution flow rate in each grating channel, L is the total grating length, is the system sealing pressure, is the particle size used for filling.

3. The method for making a neutron absorption grating by particle filling according to claim 2, characterized in that: The method further comprises the step of arranging a filter membrane, at least arranging a filter membrane at the grating outlet.

4. The method for making a neutron absorption grating by particle filling according to any one of claims 1 to 3, characterized in that: A microfluidic pipeline is used as a circulation pipeline for the particle solution; the particle solution flows out from the outlet pipe of the inlet pipe group of the microfluidic pipeline and enters the grating inlet; the number of the outlet pipes of the inlet pipe group of the microfluidic pipeline is n / 2.

5. The method for making a neutron absorption grating by particle filling according to claim 4, characterized in that: The flow pipe inlet m value of each outlet pipe is determined according to the following formula: ； in, is the Poiseuille number, is the flow rate of the particle solution flowing through the branch in the microchannel; W is the total width of the grating, is the particle size used for filling, e is the particle packing porosity, is the hydraulic diameter of the microchannel, is the solution flow rate in each grating channel, = L / n, where L is the total length of the grating.

6. The method for making a neutron absorption grating by particle filling according to claim 5, characterized in that: The number of branches of the flow channel of the microfluidic channel is mn / 2.

7. The method for making a neutron absorption grating by particle filling according to claim 6, characterized in that: The method specifically comprises the following steps: Design and process microfluidic pipelines and filter membranes respectively; Assemble and seal the grating, filter membrane and microfluidic channel; Flushing the grating, filter membrane and microfluidic pipeline; The particle solution is injected from the inlet of the microfluidic channel until the inlet of the grating channel of the grating is completely blocked.

8. The method for making a neutron absorption grating by particle filling according to claim 7, characterized in that: The assembly process is carried out in a full water environment.

9. A device for making a neutron absorption grating by filling particles, characterized in that: It includes a grating, a microfluidic pipeline and a filter membrane. The microfluidic pipeline is connected with the inlet and outlet of the grating channel of the grating. The filter membrane at least covers the outlet position of the grating channel of the grating. The part of the filter membrane that coincides with the grating inlet position is hollow.

10. The device for making neutron absorption grating by particle filling according to claim 1, characterized in that: The number of solution inlets per grating channel is n.

11. The device for making neutron absorption grating by particle filling according to claim 9 or 10, characterized in that: The microfluidic pipeline is made of soft material.

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