A check valve and a method of manufacturing the same

Abstract

The application discloses a one-way valve and a preparation method thereof. The one-way valve comprises a first substrate, an intermediate substrate and a second substrate. The first substrate is provided with a first through hole. The intermediate substrate is connected with the first substrate. The intermediate substrate is provided with a second through hole. In the direction perpendicular to the first substrate, the profile of the first through hole is located within the profile of the second through hole. The second substrate is located on the side of the intermediate substrate away from the first substrate. The second substrate comprises a peripheral sub-substrate, a valve core body and a spring connecting body. The peripheral sub-substrate is connected with the intermediate substrate. The valve core body is connected with the peripheral sub-substrate through the spring connecting body. The vertical projection area of the valve core body and the spring connecting body on the first substrate is located within the vertical projection area of the second through hole on the first substrate. The vertical projection of the first through hole on the second substrate is located within the valve core body. The one-way valve provided by the application has simple process and low cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of micro-electro-mechanical system, and in particular to a one-way valve and a preparation method thereof. BACKGROUND

[0002] Microfluidic devices have been rapidly developed due to their significant advantages such as miniaturization, functional integration and automation, and have been widely applied in the fields of biology, medicine, environmental monitoring and the like. For many microfluidic systems such as micro-pumps, micro-mixers and micro-actuators, a one-way valve is usually a key component for providing one-way flow and realizing hierarchical or metering sample delivery.

[0003] At present, one-way valves are mainly divided into active valves and passive valves. The additional driving of the active valve increases the design cost and complexity, and is not suitable for large-scale applications. At present, the passive valve is mainly composed of mechanical moving parts, and the manufacturing and operation are extremely complex, which also hinders its application in microfluidic systems. SUMMARY

[0004] The present application provides a one-way valve and a preparation method thereof to solve the problem of high design cost and complexity of the current one-way valve.

[0005] In a first aspect, the present application provides a one-way valve, comprising: a first substrate, an intermediate substrate and a second substrate.

[0006] The first substrate is provided with a first through hole; the intermediate substrate is located on one side of the first substrate and connected with the first substrate; the intermediate substrate is provided with a second through hole, and the diameter of the second through hole is greater than that of the first through hole; in the direction perpendicular to the first substrate, the contour of the first through hole is located within the contour of the second through hole;

[0007] The second substrate is located on the side of the intermediate substrate away from the first substrate, and the second substrate comprises a peripheral sub-substrate, a valve core body and a spring connecting body; the peripheral sub-substrate is connected with the intermediate substrate, the peripheral sub-substrate surrounds the valve core body, and the valve core body is connected with the peripheral sub-substrate through the spring connecting body;

[0008] The vertical projection area of the valve core body and the spring connecting body on the first substrate is located within the vertical projection area of the second through hole on the first substrate, and the vertical projection of the first through hole on the second substrate is located within the valve core body;

[0009] When the fluid flows in the direction of the second substrate pointing to the first substrate, the valve core body moves in the direction of the second substrate pointing to the first substrate and contacts the first substrate to block the fluid flow; when the fluid flows in the direction of the first substrate pointing to the second substrate, the valve core body moves in the direction of the first substrate pointing to the second substrate, and the fluid flows.

[0010] Optionally, the side of the second substrate away from the intermediate substrate is further provided with a hollow part;

[0011] The vertical projection area of the valve core body and the spring connecting body on the first substrate is located within the vertical projection area of the hollow on the first substrate, and the hollow exposes the valve core body and the spring connecting body.

[0012] Optionally, the thickness of the valve core body is less than the thickness of the peripheral sub-substrate.

[0013] Optionally, the first bonding connection layer is arranged on the side of the first substrate close to the intermediate substrate, the second bonding connection layer is arranged on the side of the intermediate substrate close to the first substrate and the side of the intermediate substrate close to the second substrate, and the third bonding connection layer is arranged on the side of the peripheral sub-substrate close to the intermediate substrate, and the third bonding connection layer is arranged on the side of the valve core body close to the first substrate.

[0014] The first bonding connection layer on the side of the first substrate close to the intermediate substrate is used for bonding connection with the second bonding connection layer on the side of the intermediate substrate close to the first substrate, the second bonding connection layer on the side of the intermediate substrate close to the second substrate is used for bonding connection with the third bonding connection layer on the side of the peripheral sub-substrate close to the intermediate substrate, and the third bonding connection layer on the side of the valve core body close to the first substrate is used for sealing connection with the first bonding connection layer on the side of the first substrate close to the intermediate substrate when the valve core body moves in the direction of the first substrate directed by the second substrate.

[0015] Optionally, the first bonding connection layer comprises a first polydimethylsiloxane layer, the second bonding connection layer comprises a second polydimethylsiloxane layer, and the third bonding connection layer comprises a third polydimethylsiloxane layer.

[0016] Optionally, the first substrate comprises a first silicon substrate, the intermediate substrate comprises a second silicon substrate, and the second substrate comprises a third silicon substrate.

[0017] In a second aspect, the present application provides a preparation method of a one-way valve, and the preparation method comprises the following steps:

[0018] A first substrate is provided; the first substrate is provided with a first through hole, and the first substrate is provided with a first bonding connection layer on one side thereof;

[0019] An intermediate substrate is provided; the intermediate substrate is provided with a second through hole, and the diameter of the second through hole is greater than that of the first through hole; the intermediate substrate is provided with a second bonding connection layer on two sides thereof;

[0020] A second substrate is provided; the second substrate comprises a peripheral sub-substrate, a valve core body and a spring connecting body; the peripheral sub-substrate surrounds the valve core body, the valve core body is connected with the peripheral sub-substrate through the spring connecting body, and the peripheral sub-substrate is provided with a third bonding connection layer on one side thereof, and the valve core body is provided with a third bonding connection layer on one side thereof;

[0021] aligning and bonding connecting one side of the first substrate provided with the first bonding connecting layer with one side of the intermediate substrate provided with the second bonding connecting layer, so that in the direction perpendicular to the first substrate, the profile of the first through hole is within the profile of the second through hole; aligning and bonding connecting the other side of the intermediate substrate provided with the second bonding connecting layer with one side of the peripheral sub-substrate provided with the third bonding connecting layer, so that the vertical projection area of the valve core body and the spring connecting body on the first substrate is within the vertical projection area of the second through hole on the first substrate, and the vertical projection of the first through hole on the second substrate is within the valve core body.

[0022] Optionally, the first substrate is provided, comprising:

[0023] The first silicon substrate is provided;

[0024] The first silicon substrate is etched to form the first through hole;

[0025] The first polydimethylsiloxane layer is grown on one side of the first silicon substrate to form the first bonding connecting layer on one side of the first silicon substrate, so as to form the first substrate;

[0026] The intermediate substrate is provided, comprising:

[0027] The second silicon substrate is provided;

[0028] The second silicon substrate is etched to form the second through hole;

[0029] The second polydimethylsiloxane layer is grown on both sides of the second silicon substrate to form the second bonding connecting layer on both sides of the second silicon substrate, so as to form the intermediate substrate.

[0030] Optionally, the first polydimethylsiloxane layer is grown on one side of the first silicon substrate, comprising:

[0031] The polydimethylsiloxane is spin-coated on one side of the first silicon substrate, baked at a first temperature for a first duration, and then washed in an organic solvent to grow the first polydimethylsiloxane layer on one side of the first silicon substrate;

[0032] The second polydimethylsiloxane layer is grown on both sides of the second silicon substrate, comprising:

[0033] The polydimethylsiloxane is spin-coated on both sides of the second silicon substrate, baked at a first temperature for a first duration, and then washed in an organic solvent to grow the second polydimethylsiloxane layer on both sides of the second silicon substrate.

[0034] Optionally, the second substrate is provided, comprising:

[0035] The third silicon substrate is provided;

[0036] One side of the third silicon substrate is pattern etched to form a spring connecting body; the etching depth is less than the thickness of the third silicon substrate;

[0037] The other side of the third silicon substrate is etched until the spring connecting body is exposed to form a valve core body and a hollow; the vertical projection area of the valve core body and the spring connecting body on the first substrate is within the vertical projection area of the hollow on the first substrate, and the hollow exposes the valve core body and the spring connecting body;

[0038] A third polydimethylsiloxane layer is grown on one side of the peripheral sub-substrate and one side of the valve core body to form a third bonding connection layer on one side of the peripheral sub-substrate and one side of the valve core body; to form a second substrate.

[0039] Optionally, growing a third polydimethylsiloxane layer on one side of the peripheral sub-substrate and one side of the valve core body comprises:

[0040] Spin coating polydimethylsiloxane on one side of the peripheral sub-substrate and one side of the valve core body, baking for a first duration in an environment at a first temperature, and then cleaning in an organic solvent to grow a third polydimethylsiloxane layer on one side of the peripheral sub-substrate and one side of the valve core body.

[0041] Optionally, aligning and bonding connecting the side of the first substrate provided with the first bonding connection layer to the side of the intermediate substrate provided with the second bonding connection layer, and aligning and bonding connecting the other side of the intermediate substrate provided with the second bonding connection layer to the side of the peripheral sub-substrate provided with the third bonding connection layer comprises:

[0042] Using oxygen plasma to treat the first bonding connection layer, the second bonding connection layer and the third bonding connection layer for a second duration;

[0043] Aligning the side of the first substrate provided with the first bonding connection layer to the side of the intermediate substrate provided with the second bonding connection layer, and aligning the other side of the intermediate substrate provided with the second bonding connection layer to the side of the peripheral sub-substrate provided with the third bonding connection layer;

[0044] Performing a bonding process at a temperature less than or equal to the second temperature to achieve bonding connection of the first substrate, the intermediate substrate and the second substrate.

[0045] The technical scheme of the embodiment of the present application, the one-way valve is composed of three layers of substrates, and can be bonded to each other. The first substrate can be provided with a first fluid through hole (first through hole), and the middle substrate can be provided with a second fluid through hole (second through hole) with a larger diameter. The second substrate includes a spring connecting body and a fluid flow channel formed by the interstice between the valve core body and the peripheral sub-substrate. The valve core body can be arranged in the middle, and the valve core body can be connected with the peripheral sub-substrate through the spring connecting body, so that the fluid can flow in the direction from the first substrate to the second substrate. The one-way valve provided by the embodiment of the present application can be processed based on a semiconductor wafer by using a micro-electro-mechanical system process, has the advantages of miniaturization, batch production, controllable cost, realization of various complex structures, and the like, and can be applied to various fluid control applications. The one-way valve provided by the embodiment of the present application has simple process and low cost, can be integrated by using a micro-electro-mechanical system process, does not need to be assembled, has good process consistency, has low batch production cost, has simple structure, good impact resistance and is not easy to be damaged.

[0046] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present application, nor is it used to limit the scope of the present application. Other features of the present application will become apparent from the following description. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0048] Figure 1 is a cross-sectional structure schematic diagram of a one-way valve provided by the embodiment of the present application;

[0049] Figure 2 is a top view structure schematic diagram of a second substrate provided by the embodiment of the present application;

[0050] Figure 3 is a working schematic diagram of a one-way valve provided by the embodiment of the present application;

[0051] Figure 4 is a working schematic diagram of another one-way valve provided by the embodiment of the present application;

[0052] Figure 5 is a flow chart of a preparation method of a one-way valve provided by the embodiment of the present application;

[0053] Figures 6-8 is a structure schematic diagram corresponding to part of steps in a preparation method of a one-way valve provided by the embodiment of the present application;

[0054] Figure 9 is a flow chart of another preparation method of a one-way valve provided by an embodiment of the present application;

[0055] Figures 10-16 is a structure diagram corresponding to part of steps in the preparation method of another one-way valve provided by an embodiment of the present application;

[0056] Figure 17 is a mask pattern diagram provided by an embodiment of the present application;

[0057] Figure 18 is a flow chart of another preparation method of a one-way valve provided by an embodiment of the present application;

[0058] Figure 19 is a flow chart of another preparation method of a one-way valve provided by an embodiment of the present application. DETAILED DESCRIPTION

[0059] In order to make the personnel in the technical field better understand the present application scheme, the technical scheme in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present application.

[0060] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not necessarily have to include only those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to the process, method, product or device.

[0061] Figure 1 is a cross-sectional structure diagram of a one-way valve provided by an embodiment of the present application, Figure 2 is a top view structure diagram of a second substrate provided by an embodiment of the present application, Figure 3 is a working diagram of a one-way valve provided by an embodiment of the present application, Figure 4 is a working diagram of another one-way valve provided by an embodiment of the present application, wherein the straight line AB in Figure 2 is a working diagram of another one-way valve provided by an embodiment of the present application, wherein the straight line AB in Figure 2The second substrate shown can be cut to obtain Figure 1 The second substrate shown can be cut to obtain Figures 1-4 As shown, the one-way valve comprises a first substrate 1, an intermediate substrate 2 and a second substrate 3. The first substrate 1 is provided with a first through hole 11. The intermediate substrate 2 is located on one side of the first substrate 1 and is connected with the first substrate 1. The intermediate substrate 2 is provided with a second through hole 21, the diameter of the second through hole 21 is greater than the diameter of the first through hole 11, and in the direction perpendicular to the first substrate 1, the contour of the first through hole 11 is within the contour of the second through hole 21. The second substrate 3 is located on the side of the intermediate substrate 2 away from the first substrate 1, and the second substrate 3 comprises a peripheral sub-substrate 31, a valve core body 32 and a spring connecting body 33, the peripheral sub-substrate 31 is connected with the intermediate substrate 2, the peripheral sub-substrate 31 surrounds the valve core body 32, and the valve core body 32 is connected with the peripheral sub-substrate 31 through the spring connecting body 33. The vertical projection area of the valve core body 32 and the spring connecting body 33 on the first substrate 1 is within the vertical projection area of the second through hole 21 on the first substrate 1, and the vertical projection of the first through hole 11 on the second substrate 3 is within the valve core body 32. When the fluid flows in the direction of the second substrate 3 pointing to the first substrate 1, the valve core body 32 moves in the direction of the second substrate 3 pointing to the first substrate 1 and contacts the first substrate 1 to block the fluid flow. When the fluid flows in the direction of the first substrate 1 pointing to the second substrate 3, the valve core body 32 moves in the direction of the first substrate 1 pointing to the second substrate 3, and the fluid flows.

[0062] Specifically, the one-way valve provided by the embodiment of the present application can comprise a first substrate 1, an intermediate substrate 2 and a second substrate 3, the first substrate 1, the intermediate substrate 2 and the second substrate 3 can comprise a semiconductor material wafer, and exemplarily, the first substrate 1, the intermediate substrate 2 and the second substrate 3 can comprise a silicon substrate. The embodiment of the present application can be based on the processing of the semiconductor material wafer by using a micro-electro-mechanical system (MEMS) process, so as to realize the preparation of the one-way valve.

[0063] The first substrate 1 can be provided with a first through hole 11, the intermediate substrate 2 is located on one side of the first substrate 1, and the intermediate substrate 2 can be bonded and connected with the first substrate 1. The intermediate substrate 2 can be provided with a second through hole 21, and the diameter of the second through hole 21 can be greater than the diameter of the first through hole 11. In the direction of the intermediate substrate 2 pointing to the first substrate 1, the second through hole 21 can completely expose the first through hole 11. The second substrate 3 can be located on the side of the intermediate substrate 2 away from the first substrate 1, and the peripheral sub-substrate 31 of the second substrate 3 can be in contact with the intermediate substrate 2, and the peripheral sub-substrate 31 can be bonded and connected with the intermediate substrate 2.

[0064] The peripheral sub-substrate 31 can be arranged around the valve core body 32, and the valve core body 32 can be connected with the peripheral sub-substrate 31 through the spring connecting body 33. The valve core body 32 can move up and down by stretching the spring connecting body 33 under the action of pressure. The first substrate 1, the intermediate substrate 2 and the second substrate 3 jointly constitute a one-way valve structure, and the one-way valve provided by the embodiment of the application can realize one-way flow of fluid, wherein the fluid can include gas or liquid, which is not limited here.

[0065] As shown in Figure 2 and Figure 3 When the fluid flows in the direction of the second substrate 3 pointing to the first substrate 1, or when the pressure on the side of the second substrate 3 away from the first substrate 1 is greater than the pressure on the side of the first substrate 1 away from the second substrate 3, the valve core body 32 will move in the direction of the second substrate 3 pointing to the first substrate 1 under the action of pressure difference, and the spring connecting body 33 will be deformed, so that the valve core body 32 is in sealing contact with the side of the first substrate 1 close to the second substrate 3, thereby blocking the flow of fluid.

[0066] As shown in Figure 2 and Figure 4 When the fluid flows in the direction of the first substrate 1 pointing to the second substrate 3, or when the pressure on the side of the first substrate 1 away from the second substrate 3 is greater than the pressure on the side of the second substrate 3 away from the first substrate 1, the valve core body 32 will move in the direction of the first substrate 1 pointing to the second substrate 3 under the action of pressure difference, and the spring connecting body 33 will be deformed, and the valve core body 32 is away from the first substrate 1, and the fluid flows through the first through hole 11, the second through hole 21 and the gap between the valve core body 32 and the peripheral sub-substrate 31.

[0067] When there is no fluid and pressure difference on the side of the first substrate 1 away from the second substrate 3 and on the side of the second substrate 3 away from the first substrate 1, the spring connecting body 33 restores, and at the same time drives the valve core body 32 to reset.

[0068] The technical scheme of the embodiment of the present application, the one-way valve is composed of three layers of substrates, and can be bonded to each other. The first substrate 1 can be provided with a first fluid through hole (first through hole 11), and the middle substrate 2 can be provided with a second fluid through hole (second through hole 21) with a larger diameter. The second substrate 3 includes a spring connecting body 33 and a fluid flow channel formed by the interstice between the valve core body 32 and the peripheral sub-substrate 31. The valve core body 32 can be arranged in the middle, and the valve core body 32 can be connected to the peripheral sub-substrate 31 through the spring connecting body 33. The fluid can flow in the direction from the first substrate 1 to the second substrate 3. The one-way valve provided by the embodiment of the present application can be processed based on the semiconductor wafer by using the micro-electro-mechanical system process, has the advantages of miniaturization, batch production, controllable cost, realization of various complex structures and the like, and can be applied to various fluid control applications. The one-way valve provided by the embodiment of the present application has simple process and low cost, can be integrated by using the micro-electro-mechanical system integrated process, does not need to be assembled, has good process consistency, low batch production cost, simple structure, good impact resistance and is not easy to be damaged.

[0069] The one-way valve provided by the embodiment of the present application can be integrated in a small air pump to realize a passive air valve for one-way gas flow. In addition to the air pump, the one-way valve can also be applied to a MEMS heat sink and the like, and can also be applied to a scene of one-way liquid flow.

[0070] Optionally, on the basis of each of the above embodiments, with reference to Figures 1-4 , the second substrate 3 is further provided with a hollow part 34 away from the middle substrate 2. The vertical projection area of the valve core body 32 and the spring connecting body 33 on the first substrate 1 is located within the vertical projection area of the hollow part 34 on the first substrate 1, and the hollow part 34 exposes the valve core body 32 and the spring connecting body 33. The thickness of the valve core body 32 is less than the thickness of the peripheral sub-substrate 31.

[0071] Specifically, the second substrate 3 can be further provided with a hollow part 34 away from the first substrate 1. The hollow part 34 can expose the valve core body 32 and the spring connecting body 33, and in the direction in which the valve core body 32 points to the peripheral sub-substrate 31, the hollow part 34 can extend into the peripheral sub-substrate 31. The hollow structure makes the thickness of the valve core body 32 and the thickness of the spring connecting body 33 thinner, and the contact area of the spring connecting body 33 with the valve core body 32 and the peripheral sub-substrate 31 smaller, which can effectively reduce the rigidity of the spring connecting body 33, thereby improving the activity range and sensitivity of the valve core plate 32. In addition, the fluid flow rate can also be improved when the fluid flows.

[0072] Optionally, on the basis of each of the above embodiments, with reference to Figure 1 and Figure 2The first substrate 1 is provided with a first bonding layer 12 on the side close to the intermediate substrate 2. The intermediate substrate 2 is provided with a second bonding layer 22 on the side close to the first substrate 1 and on the side close to the second substrate 3. The peripheral sub-substrate 31 is provided with a third bonding layer 35 on the side close to the intermediate substrate 2. The valve core body 32 is provided with a third bonding layer 35 on the side close to the first substrate 1. The first bonding layer 12 on the side of the first substrate 1 close to the intermediate substrate 2 is bonded to the second bonding layer 22 on the side of the intermediate substrate 2 close to the first substrate 1. The second bonding layer 22 on the side of the intermediate substrate 2 close to the second substrate 3 is bonded to the third bonding layer 35 on the side of the peripheral sub-substrate 31 close to the intermediate substrate 2. The third bonding layer 35 on the side of the valve core body 32 close to the first substrate 1 is bonded to the first bonding layer 12 on the side of the first substrate 1 close to the second substrate 3 when the valve core body 32 moves in the direction of the first substrate 1 from the second substrate 3.

[0073] Specifically, the first substrate 1 is provided with a first bonding layer 12 on the side close to the intermediate substrate 2. The intermediate substrate 2 is provided with a second bonding layer 22 on the side close to the first substrate 1. The first bonding layer 12 is bonded to the second bonding layer 22. The intermediate substrate 2 is provided with a second bonding layer 22 on the side close to the second substrate 3. The peripheral sub-substrate 31 is provided with a third bonding layer 35 on the side close to the intermediate substrate 2. The second bonding layer 22 is bonded to the third bonding layer 35. In this way, the first substrate 1, the intermediate substrate 2, and the second substrate 3 together form a stable one-way valve.

[0074] The valve core body 32 is also provided with a third bonding layer 35 on the side close to the first substrate 1. When the fluid flows in the direction of the first substrate 1 from the second substrate 3, or when the pressure on the side of the second substrate 3 away from the first substrate 1 is greater than the pressure on the side of the first substrate 1 away from the second substrate 3, the valve core body 32 moves in the direction of the first substrate 1 from the second substrate 3 under the pressure difference, and the spring connecting body 33 deforms, so that the valve core body 32 contacts the side of the first substrate 1 close to the second substrate 3. The third bonding layer 35 on the surface of the valve core body 32 contacts the first bonding layer 12 on the surface of the first substrate 1, thereby achieving the sealing connection between the valve core body 32 and the first substrate 1, improving the sealing effect, and thereby blocking the flow of fluid.

[0075] Optionally, on the basis of the above embodiments, with reference to Figure 1 and Figure 2The first bonding connection layer 12 comprises a first polydimethylsiloxane layer; the second bonding connection layer 22 comprises a second polydimethylsiloxane layer; and the third bonding connection layer 35 comprises a third polydimethylsiloxane layer.

[0076] Specifically, the first bonding connection layer 12, the second bonding connection layer 22 and the third bonding connection layer 35 can all be made of a high polymer material. For example, the first bonding connection layer 12, the second bonding connection layer 22 and the third bonding connection layer 35 can all comprise a polydimethylsiloxane (PDMS) layer. In some embodiments of the present application, the first bonding connection layer 12, the second bonding connection layer 22 and the third bonding connection layer 35 can further comprise at least one of an epoxy resin, a benzocyclobutene or a polyimide, without being specifically limited herein.

[0077] Optionally, based on the above embodiments, continuing to refer to Figure 1 and Figure 2 , the first substrate 1 comprises a first silicon substrate, the intermediate substrate 2 comprises a second silicon substrate, and the second substrate 3 comprises a third silicon substrate.

[0078] Specifically, the first substrate 1, the intermediate substrate 2 and the second substrate 3 can comprise semiconductor wafer, for example, the first substrate 1, the intermediate substrate 2 and the second substrate 3 can comprise a silicon substrate. In some embodiments of the present application, the first substrate 1, the intermediate substrate 2 and the second substrate 3 can further comprise at least one of a silicon carbide substrate, a gallium nitride substrate, etc., without being specifically limited herein. The one-way valve provided by the embodiments of the present application can be processed based on the semiconductor wafer by using the micro-electro-mechanical system process, and has the advantages of miniaturization, batch production, controllable cost, and realization of various complex structures, etc., thereby facilitating the development of a new type of one-way valve applicable to various fluid control applications.

[0079] Figure 5 is a flow chart of a preparation method of a one-way valve provided by the embodiments of the present application, Figures 6-8 is a structure diagram corresponding to part of steps in the preparation method of a one-way valve provided by the embodiments of the present application, as shown in Figure 5 , the preparation method comprises:

[0080] S100: providing a first substrate; the first substrate is provided with a first through hole, and one side of the first substrate is provided with a first bonding connection layer.

[0081] Specifically, as shown in Figure 6 , first, a first substrate 1 can be provided, and the first substrate 1 can comprise a semiconductor material wafer, for example, the first substrate 1 can comprise a silicon substrate. The first substrate 1 can be provided with a first through hole 11, and one side of the first substrate 1 is provided with a first bonding connection layer 12.

[0082] S110: providing an intermediate substrate; the intermediate substrate is provided with a second through hole, the diameter of the second through hole is larger than the diameter of the first through hole; the two surfaces of the intermediate substrate are provided with a second bonding layer.

[0083] Specifically, as shown in Figure 7 , then the intermediate substrate 2 is provided, which can include a semiconductor material wafer, and the intermediate substrate 2 can include a silicon substrate. The intermediate substrate 2 can be provided with a second through hole 21, and the diameter of the second through hole 21 can be larger than the diameter of the first through hole 11. The two surfaces of the intermediate substrate 2 are provided with a second bonding layer 21.

[0084] S120: providing a second substrate; the second substrate includes a peripheral sub-substrate, a valve core body and a spring connecting body; the peripheral sub-substrate surrounds the valve core body, and the valve core body is connected with the peripheral sub-substrate through the spring connecting body; one surface of the peripheral sub-substrate and one surface of the valve core body are provided with a third bonding layer.

[0085] Specifically, as shown in Figure 2 and Figure 8 , the second substrate 3 is further provided, which can include a semiconductor material wafer, and the second substrate 3 can include a silicon substrate. The peripheral sub-substrate 31 can surround the valve core body 32, and the valve core body 32 can be connected with the peripheral sub-substrate 31 through the spring connecting body 33. The valve core body 32 can move up and down by stretching the spring connecting body 33 under the action of pressure.

[0086] One surface of the peripheral sub-substrate 31 and one surface of the valve core body 32 are provided with a third bonding layer 35, and the side of the second substrate 3 away from the first substrate 1 can be further provided with a hollow part 34, which can expose the valve core body 32 and the spring connecting body 33, and along the direction of the valve core body 32 pointing to the peripheral sub-substrate 31, the hollow part 34 can extend into the peripheral sub-substrate 31. The hollow structure makes the thickness of the valve core body 32 and the spring connecting body 33 thinner, and the contact area of the spring connecting body 33 with the valve core body 32 and the peripheral sub-substrate 31 smaller, which can effectively reduce the rigidity of the spring connecting body 33, thereby improving the activity range and sensitivity of the valve core plate 32, and also improving the fluid flow rate when the fluid flows.

[0087] S130: align and bond connect one side of the first substrate provided with the first bonding connection layer with one side of the intermediate substrate provided with the second bonding connection layer, so that in the direction perpendicular to the first substrate, the profile of the first through hole is within the profile of the second through hole; align and bond connect the other side of the intermediate substrate provided with the second bonding connection layer with one side of the peripheral sub substrate provided with the third bonding connection layer, so that the vertical projection area of the valve core body and the spring connection body on the first substrate is within the vertical projection area of the second through hole on the first substrate, and the vertical projection of the first through hole on the second substrate is within the valve core body.

[0088] Specifically, as shown in FIG. 1, after the preparation of the first substrate 1, the intermediate substrate 2 and the second substrate 3 is completed, the first substrate 1, the intermediate substrate 2 and the second substrate 3 can be aligned and bonded to form a one-way valve. Figure 1

[0089] Optionally, based on the above embodiments, Figure 9 is a flow chart of another preparation method of a one-way valve provided by the embodiments of the present application, Figures 10-16 is a structure diagram corresponding to part of the steps in the preparation method of another one-way valve provided by the embodiments of the present application, as shown in FIG. 2, the preparation method comprises: Figure 9

[0090] S200: providing a first silicon substrate.

[0091] Specifically, as shown in FIG. 1, the first silicon substrate 10 is provided, and the thickness of the first silicon substrate 10 can be about 425 um. Figure 10

[0092] S210: etching the first silicon substrate to form a first through hole.

[0093] Specifically, as shown in FIG. 1, the first silicon substrate 10 is etched, which can be achieved by wet etching or dry etching, which is not limited here. For example, KOH wet etching process can be used to etch the first silicon substrate 10 to form a first through hole 11 with a diameter of about 2300 um. In some embodiments of the present application, the thickness of the first silicon substrate 10 and the diameter of the first through hole 11 can be arbitrarily set according to actual needs, which is not limited here. Figure 11

[0094] S220: growing a first polydimethylsiloxane layer on one side of the first silicon substrate to form a first bonding connection layer on one side of the first silicon substrate; to form a first substrate.

[0095] Specifically, as shown in FIG. 1, the first silicon substrate 10 is etched, which can be achieved by wet etching or dry etching, which is not limited here. For example, KOH wet etching process can be used to etch the first silicon substrate 10 to form a first through hole 11 with a diameter of about 2300 um. In some embodiments of the present application, the thickness of the first silicon substrate 10 and the diameter of the first through hole 11 can be arbitrarily set according to actual needs, which is not limited here. Figure 11 Figure 6 ​​​​​As shown, a first polydimethylsiloxane layer is grown and formed on one side of the first silicon substrate 10 to form a first bonding connection layer 12 on one side of the first silicon substrate 10; thereby forming the first substrate 1.

[0096] S230: Provides a second silicon substrate.

[0097] Specifically, such as Figure 12 As shown, a second silicon substrate 20 is provided, and the thickness of the second silicon substrate 20 can be about 300um.

[0098] S240: Etch the second silicon substrate to form the second through-hole.

[0099] Specifically, such as Figure 13 As shown, the etching process for the second silicon substrate 20 can be performed using either wet etching or dry etching methods, without specific limitations. For example, a KOH wet etching process can be used to etch the second silicon substrate 20 to form a second via 21 with a diameter of approximately 7000 μm. In some embodiments of the present invention, the thickness of the second silicon substrate 20 and the diameter of the second via 21 can be arbitrarily set according to actual needs, without specific limitations.

[0100] S250: A second polydimethylsiloxane layer is grown on both sides of the second silicon substrate to form a second bonding connection layer on both sides of the second silicon substrate; thereby forming an intermediate substrate.

[0101] Specifically, such as Figure 13 and Figure 7 As shown, a second polydimethylsiloxane layer is grown on both sides of the second silicon substrate 20 to form a second bonding connection layer 22 on both sides of the second silicon substrate 20; thereby forming an intermediate substrate 2.

[0102] S260: Provides a third silicon substrate.

[0103] Specifically, such as Figure 14 As shown, a third silicon substrate 30 is provided, and the thickness of the third silicon substrate 30 can be about 425um.

[0104] S270: Pattern etching is performed on one side of the third silicon substrate to form a spring connector; the etching depth is less than the thickness of the third silicon substrate.

[0105] Specifically, Figure 17 This is a schematic diagram of a mask pattern provided in an embodiment of the present invention, such as... Figure 2 , Figure 15 and Figure 17 As shown, the third silicon substrate 30 is prepared according to... Figure 17 The mask pattern shown is etched, in which Figure 17The area of the third silicon substrate 30 covered by the pattern is the area that needs to be etched away.

[0106] The wet etching or dry etching method can be used, which is not specifically limited here. For example, a KOH wet etching process can be used to etch the third silicon substrate 30, and the etching depth can be 100 um, forming Figure 2 The spring connecting body 33 is shown. In some embodiments of the present application, the thickness of the third silicon substrate 30 and the etching depth can be arbitrarily set according to actual needs, which is not specifically limited here.

[0107] S280: Etching the other side of the third silicon substrate until the spring connecting body is exposed to form a valve core body and a hollow; the vertical projection area of the valve core body and the spring connecting body on the first substrate is within the vertical projection area of the hollow on the first substrate, and the hollow exposes the valve core body and the spring connecting body.

[0108] Specifically, as shown in Figure 16 The wet etching or dry etching method can be used, which is not specifically limited here. For example, a KOH wet etching process can be used to etch the other side of the third silicon substrate 30 until the structure of the spring connecting body 33 etched in S270 is exposed, to form a valve core body 32 and a hollow 34 with a thickness of 100 um. The thickness of the valve core body 32 can be arbitrarily set according to actual needs, which is not specifically limited here.

[0109] S290: Growing a third polydimethylsiloxane layer on one side of the peripheral sub-substrate and one side of the valve core body to form a third bonding connection layer on one side of the peripheral sub-substrate and one side of the valve core body; to form a second substrate.

[0110] Specifically, as shown in Figure 16 and Figure 8 A third polydimethylsiloxane layer is grown on one side of the peripheral sub-substrate 31 and one side of the valve core body 32 to form a third bonding connection layer 35 on one side of the peripheral sub-substrate 31 and one side of the valve core body 32; to form a second substrate 3.

[0111] S291: align and bond connect one side of the first substrate provided with the first bonding connection layer with one side of the intermediate substrate provided with the second bonding connection layer, so that in the direction perpendicular to the first substrate, the profile of the first through hole is within the profile of the second through hole; align and bond connect the other side of the intermediate substrate provided with the second bonding connection layer with one side of the peripheral sub-substrate provided with the third bonding connection layer, so that the vertical projection area of the valve core body and the spring connection body on the first substrate is within the vertical projection area of the second through hole on the first substrate, and the vertical projection of the first through hole on the second substrate is within the valve core body.

[0112] Optionally, on the basis of each of the above embodiments, Figure 18 is a flowchart of another preparation method of a one-way valve provided by an embodiment of the present application, as shown in the figure, the preparation method comprises the following steps: Figure 18

[0113] S300: providing a first silicon substrate.

[0114] S310: etching the first silicon substrate to form a first through hole.

[0115] S320: spin coating polydimethylsiloxane on one side of the first silicon substrate, baking for a first duration in an environment at a first temperature, and then cleaning in an organic solvent to form a first polydimethylsiloxane layer on one side of the first silicon substrate.

[0116] Specifically, as shown in the figures, Figure 11 and Figure 6 spin coating polydimethylsiloxane on one side of the first silicon substrate 10, vacuum degassing, baking for a first duration in an environment at a first temperature, the first temperature can be 100℃, and the first duration can be 1 hour. Then clean in an organic solvent (such as acetone) to form a first polydimethylsiloxane layer on one side of the first silicon substrate 10, and the thickness of the first polydimethylsiloxane layer can be about 5nm.

[0117] S330: providing a second silicon substrate.

[0118] S340: etching the second silicon substrate to form a second through hole.

[0119] S350: spin coating polydimethylsiloxane on both sides of the second silicon substrate, baking for a first duration in an environment at a first temperature, and then cleaning in an organic solvent to form a second polydimethylsiloxane layer on both sides of the second silicon substrate.

[0120] Specifically, as shown in the figures, Figure 13 and Figure 7 ​As shown, polydimethylsiloxane is spin-coated onto both sides of the second silicon substrate 20, degassed under vacuum, and baked at a first temperature for a first duration, which can be 100°C or 1 hour. Then, it is cleaned in an organic solvent (such as acetone) to form a second polydimethylsiloxane layer on both sides of the second silicon substrate 20. The thickness of the second polydimethylsiloxane layer can be approximately 5 nm.

[0121] S360: Provides a third silicon substrate.

[0122] S370: Pattern etching is performed on one side of the third silicon substrate to form a spring connector; the etching depth is less than the thickness of the third silicon substrate.

[0123] S380: Etch the other side of the third silicon substrate until the spring connector is exposed to form the valve core and the cutout; the vertical projection area of ​​the valve core and the spring connector on the first substrate is located within the vertical projection area of ​​the cutout on the first substrate, and the cutout exposes the valve core and the spring connector.

[0124] S390: Polydimethylsiloxane is spin-coated onto one side of the peripheral sub-substrate and one side of the valve core, baked at a first temperature for a first time, and then cleaned in an organic solvent to form a third polydimethylsiloxane layer on one side of the peripheral sub-substrate and one side of the valve core.

[0125] Specifically, such as Figure 16 and Figure 8 As shown, polydimethylsiloxane is spin-coated onto one side of the peripheral sub-substrate 31 and one side of the valve core 32. After vacuum degassing, it is baked at a first temperature for a first duration, which can be 100°C or 1 hour. Then, it is cleaned in an organic solvent (such as acetone) to grow a third polydimethylsiloxane layer on one side of the peripheral sub-substrate 31 and one side of the valve core 32. The thickness of the third polydimethylsiloxane layer can be approximately 5 nm.

[0126] S391: Align and bond the side of the first substrate with the first bonding layer to the side of the intermediate substrate with the second bonding layer, so that the outline of the first through hole is located within the outline of the second through hole in the direction perpendicular to the first substrate; align and bond the other side of the intermediate substrate with the second bonding layer to the side of the peripheral sub-substrate with the third bonding layer, so that the vertical projection area of ​​the valve core and the spring connector on the first substrate is located within the vertical projection area of ​​the second through hole on the first substrate, and the vertical projection of the first through hole on the second substrate is located within the valve core.

[0127] Optionally, based on the above embodiments, Figure 19is a flow chart of another method for manufacturing a one-way valve according to an embodiment of the present application, as shown in Figure 19 The method comprises the following steps:

[0128] S400: providing a first silicon substrate.

[0129] S410: etching the first silicon substrate to form a first through hole.

[0130] S420: growing a first polydimethylsiloxane layer on one side of the first silicon substrate to form a first bonding connection layer on one side of the first silicon substrate; to form a first substrate.

[0131] S430: providing a second silicon substrate.

[0132] S440: etching the second silicon substrate to form a second through hole.

[0133] S450: growing a second polydimethylsiloxane layer on both sides of the second silicon substrate to form a second bonding connection layer on both sides of the second silicon substrate; to form an intermediate substrate.

[0134] S460: providing a third silicon substrate.

[0135] S470: pattern etching one side of the third silicon substrate to form a spring connection body; the etching depth is less than the thickness of the third silicon substrate.

[0136] S480: etching the other side of the third silicon substrate until the spring connection body is exposed to form a valve core body and a hollow part; the vertical projection area of the valve core body and the spring connection body on the first substrate is within the vertical projection area of the hollow part on the first substrate, and the hollow part exposes the valve core body and the spring connection body.

[0137] S490: growing a third polydimethylsiloxane layer on one side of the peripheral sub-substrate and one side of the valve core body to form a third bonding connection layer on one side of the peripheral sub-substrate and one side of the valve core body; to form a second substrate.

[0138] S491: treating the first bonding connection layer, the second bonding connection layer and the third bonding connection layer for a second time length using oxygen plasma.

[0139] Specifically, as shown in Figures 6-8 After the first substrate 1, the intermediate substrate 2 and the second substrate 3 are prepared, the first bonding connection layer 12, the second bonding connection layer 22 and the third bonding connection layer 35 are treated for a second time length using oxygen plasma (O2-plasma), and the second time length can be several seconds, for example.

[0140] S492: align the first substrate provided with the first bonding connection layer on one side with the intermediate substrate provided with the second bonding connection layer on one side, and align the other side of the intermediate substrate provided with the second bonding connection layer with the peripheral sub-substrate provided with the third bonding connection layer on one side.

[0141] Specifically, as shown in FIG. 1, the first substrate 1, the intermediate substrate 2 and the second substrate 3 can be aligned, and the first substrate 1 provided with the first bonding connection layer 12 on one side is aligned with the intermediate substrate 2 provided with the second bonding connection layer 22 on one side, and the other side of the intermediate substrate 2 provided with the second bonding connection layer 22 is aligned with the peripheral sub-substrate 31 provided with the third bonding connection layer 35 on one side. Figure 1

[0142] S493: performing a bonding process at less than or equal to the second temperature to realize the bonding connection of the first substrate, the intermediate substrate and the second substrate.

[0143] Specifically, as shown in FIG. 1, the first substrate 1, the intermediate substrate 2 and the second substrate 3 can be aligned, and the first substrate 1 provided with the first bonding connection layer 12 on one side is aligned with the intermediate substrate 2 provided with the second bonding connection layer 22 on one side, and the other side of the intermediate substrate 2 provided with the second bonding connection layer 22 is aligned with the peripheral sub-substrate 31 provided with the third bonding connection layer 35 on one side. Figure 1

[0144] Specifically, as shown in FIG. 1, the first substrate 1, the intermediate substrate 2 and the second substrate 3 can be aligned, and the first substrate 1 provided with the first bonding connection layer 12 on one side is aligned with the intermediate substrate 2 provided with the second bonding connection layer 22 on one side, and the other side of the intermediate substrate 2 provided with the second bonding connection layer 22 is aligned with the peripheral sub-substrate 31 provided with the third bonding connection layer 35 on one side.

[0145] ​​It should be understood that the various forms of flow shown above can be used to reorder, add, or remove steps. For example, the steps recited in the present application can be performed in parallel, in series, or in a different order, as long as the desired results of the technical solutions of the present application can be achieved, which are not limited herein.

[0146] The above detailed description does not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A one-way valve characterized by, The application relates to a valve core and a manufacturing method thereof. The valve core comprises a first substrate, an intermediate substrate and a second substrate. The first substrate is provided with a first through hole; the intermediate substrate is located on one side of the first substrate and is connected with the first substrate; the intermediate substrate is provided with a second through hole, the diameter of the second through hole is larger than that of the first through hole; in the direction perpendicular to the first substrate, the profile of the first through hole is located within the profile of the second through hole. The second substrate is located on the side of the intermediate substrate away from the first substrate, and comprises a peripheral sub-substrate, a valve core body and a spring connecting body; the peripheral sub-substrate is connected with the intermediate substrate, the peripheral sub-substrate surrounds the valve core body, and the valve core body is connected with the peripheral sub-substrate through the spring connecting body. The vertical projection area of the valve core body and the spring connecting body on the first substrate is located within the vertical projection area of the second through hole on the first substrate, and the vertical projection of the first through hole on the second substrate is located within the valve core body. When fluid flows along the second substrate towards the first substrate, the valve core body moves along the second substrate towards the first substrate and contacts the first substrate to block the fluid flow; when fluid flows along the first substrate towards the second substrate, the valve core body moves along the first substrate towards the second substrate, and the fluid flows. The side of the second substrate away from the intermediate substrate is further provided with a hollow part. The vertical projection area of the valve core body and the spring connecting body on the first substrate is located within the vertical projection area of the hollow part on the first substrate, and the hollow part exposes the valve core body and the spring connecting body. The thickness of the valve core body is smaller than that of the peripheral sub-substrate. The first substrate is provided with a first bonding connection layer on the side close to the intermediate substrate, the intermediate substrate is provided with a second bonding connection layer on the side close to the first substrate and the side close to the second substrate, the peripheral sub-substrate is provided with a third bonding connection layer on the side close to the intermediate substrate, and the valve core body is provided with the third bonding connection layer on the side close to the first substrate. The first bonding connection layer on the side of the first substrate close to the intermediate substrate is used for bonding connection with the second bonding connection layer on the side of the intermediate substrate close to the first substrate; the second bonding connection layer on the side of the intermediate substrate close to the second substrate is used for bonding connection with the third bonding connection layer on the side of the peripheral sub-substrate close to the intermediate substrate; and the third bonding connection layer on the side of the valve core body close to the first substrate is used for sealed connection with the first bonding connection layer on the side of the first substrate close to the intermediate substrate when the valve core body moves along the second substrate towards the first substrate. The first bonding connection layer comprises a first polydimethylsiloxane layer; the second bonding connection layer comprises a second polydimethylsiloxane layer; and the third bonding connection layer comprises a third polydimethylsiloxane layer.

2. The one-way valve of claim 1, wherein The first substrate comprises a first silicon substrate, the intermediate substrate comprises a second silicon substrate, and the second substrate comprises a third silicon substrate.

3. A method of manufacturing a check valve, characterized by, Comprise: A first substrate is provided, which is provided with a first through hole, and one side of the first substrate is provided with a first bonding connection layer; An intermediate substrate is provided, which is provided with a second through hole, the diameter of the second through hole being larger than that of the first through hole; both sides of the intermediate substrate are provided with a second bonding connection layer; A second substrate is provided, which comprises a peripheral sub-substrate, a valve core body and a spring connecting body; the peripheral sub-substrate surrounds the valve core body, and the valve core body and the peripheral sub-substrate are connected through the spring connecting body; one side of the peripheral sub-substrate and one side of the valve core body are provided with a third bonding connection layer; The side of the first substrate provided with the first bonding connection layer is aligned and bonded to the side of the intermediate substrate provided with the second bonding connection layer, so that in the direction perpendicular to the first substrate, the profile of the first through hole is located within the profile of the second through hole; the other side of the intermediate substrate provided with the second bonding connection layer is aligned and bonded to the side of the peripheral sub-substrate provided with the third bonding connection layer, so that the vertical projection area of the valve core body and the spring connecting body on the first substrate is located within the vertical projection area of the second through hole on the first substrate, and the vertical projection of the first through hole on the second substrate is located within the valve core body; A second substrate is provided, comprising: A third silicon substrate is provided; One side of the third silicon substrate is patterned and etched to form the spring connecting body; the etching depth is less than the thickness of the third silicon substrate; The other side of the third silicon substrate is etched until the spring connecting body is exposed to form the valve core body and a hollow part; the vertical projection area of the valve core body and the spring connecting body on the first substrate is located within the vertical projection area of the hollow part on the first substrate, and the hollow part exposes the valve core body and the spring connecting body; A third polydimethylsiloxane layer is grown on one side of the peripheral sub-substrate and one side of the valve core body to form a third bonding connection layer on one side of the peripheral sub-substrate and one side of the valve core body; to form the second substrate; A third polydimethylsiloxane layer is grown on one side of the peripheral sub-substrate and one side of the valve core body, comprising: Polydimethylsiloxane is spin-coated and grown on one side of the peripheral sub-substrate and one side of the valve core body, baked at a first temperature for a first duration, and then cleaned in an organic solvent to grow a third polydimethylsiloxane layer on one side of the peripheral sub-substrate and one side of the valve core body; The side of the first substrate provided with the first bonding connection layer is aligned and bonded to the side of the intermediate substrate provided with the second bonding connection layer, and the other side of the intermediate substrate provided with the second bonding connection layer is aligned and bonded to the side of the peripheral sub-substrate provided with the third bonding connection layer, comprising: treating the first bonding connection layer, the second bonding connection layer and the third bonding connection layer with oxygen plasma for a second time duration; aligning one side of the first substrate provided with the first bonding connection layer with one side of the intermediate substrate provided with the second bonding connection layer, and aligning the other side of the intermediate substrate provided with the second bonding connection layer with one side of the peripheral sub-substrate provided with the third bonding connection layer; performing a bonding process at a temperature less than or equal to the second temperature to achieve the bonded connection of the first substrate, the intermediate substrate and the second substrate.

4. The method of claim 3, wherein the one-way valve is prepared by, providing a first substrate, comprising: providing a first silicon substrate; etching the first silicon substrate to form the first through hole; growing a first polydimethylsiloxane layer on one side of the first silicon substrate to form a first bonding connection layer on one side of the first silicon substrate; to form the first substrate; providing an intermediate substrate, comprising: providing a second silicon substrate; etching the second silicon substrate to form the second through hole; growing a second polydimethylsiloxane layer on both sides of the second silicon substrate to form a second bonding connection layer on both sides of the second silicon substrate; to form the intermediate substrate.

5. The method of claim 4, wherein the one-way valve is prepared by, growing a first polydimethylsiloxane layer on one side of the first silicon substrate, comprising: spin-coating polydimethylsiloxane on one side of the first silicon substrate, baking in an environment at a first temperature for a first time duration, and then cleaning in an organic solvent to grow a first polydimethylsiloxane layer on one side of the first silicon substrate; growing a second polydimethylsiloxane layer on both sides of the second silicon substrate, comprising: spin-coating polydimethylsiloxane on both sides of the second silicon substrate, baking in an environment at the first temperature for the first time duration, and then cleaning in an organic solvent to grow a second polydimethylsiloxane layer on both sides of the second silicon substrate.

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