A polyelectrolyte ion diode with adjustable rectification ratio and preparation method thereof

Abstract

This invention provides a polyelectrolyte ion diode with adjustable rectification ratio and its preparation method. The ion diode includes a microfluidic chip and a composite polyelectrolyte. The microfluidic chip has a first inlet, a second inlet, a first outlet, and a second outlet disposed therethrough. The microfluidic chip is cuboid, and its upper surface is recessed downward to form a first main channel, a second main channel, and a working channel. The two ends of the first main channel are connected to the first inlet and the first outlet, respectively. The two ends of the second main channel are connected to the second inlet and the second outlet, respectively. The middle parts of the first and second main channels are connected through the working channel. In the process of preparing the polyelectrolyte ion diode, the rectification ratio of the polyelectrolyte ion diode can be precisely controlled by adjusting the applied voltage. The operation steps are simple, and the resulting ion diode has stable performance.

Description

Technical Field

[0001] This invention relates to the field of ion diode technology, and more particularly to a polyelectrolyte ion diode with adjustable rectification ratio and its preparation method. Background Technology

[0002] Over the past few decades, electronic information technology based on solid-state electronics has developed rapidly, and the information processing capabilities of CPUs have also gradually improved. Despite this, electronic information technology still struggles to achieve high-level information processing such as intelligent reasoning. Therefore, novel information devices based on ion carriers have gradually emerged. Compared to traditional electronic information technology, these novel ion devices possess far more powerful information processing capabilities and are a key technology for developing advanced artificial intelligence. The development and research of ion diodes with ion rectification effects are of great significance to the research of novel ion devices.

[0003] In recent years, the fabrication of ion diodes using biomimetic intelligent asymmetric nanochannel membranes (BSANMs) has attracted considerable attention. While nanochannel membranes are typically fabricated through the stacking of nanomaterials, BSANMs can be constructed by introducing asymmetric geometries or surface charge distributions within the nanochannels. However, ion diodes fabricated using this method are relatively large, limiting their miniaturization and practical applications in devices. Alternatively, by fabricating p-type and n-type hydrogels and bringing them into contact, with each gel doped with a polyelectrolyte of opposite charge, a gel heterojunction is formed at the contact interface. This method can facilitate the fabrication of hydrogel ion diodes; however, it requires the separate fabrication of different hydrogels, making the process complex and limiting its widespread application.

[0004] Furthermore, by using polyelectrolytes to deposit layered layers in nanochannels to achieve sufficiently small nanochannel sizes, and then modifying the two ends of the channels with polyelectrolyte solutions carrying opposite charges, nanoscale ion diodes can be constructed. However, this method of constructing ion diodes is complex, time-consuming, and difficult to control the rectification ratio. Therefore, it is necessary to propose a simple, widely applicable, and tunable method for fabricating polyelectrolyte ion diodes. Summary of the Invention

[0005] In view of the problems mentioned above, such as complex preparation process, difficulty in adjusting rectification ratio and poor durability of existing technologies, a polyelectrolyte ion diode with adjustable rectification ratio and its preparation method are provided.

[0006] The technical means employed in this invention are as follows:

[0007] A polyelectrolyte ion diode with adjustable rectification ratio, comprising a microfluidic chip and a composite polyelectrolyte;

[0008] The microfluidic chip is bonded to a substrate. A first inlet, a second inlet, a first outlet, and a second outlet are disposed through the microfluidic chip. The microfluidic chip is cuboid, and its upper surface is recessed downwards to form a first main channel, a second main channel, and a working channel. The two ends of the first main channel are connected to the first inlet and the first outlet, respectively. The two ends of the second main channel are connected to the second inlet and the second outlet, respectively. The middle portions of the first and second main channels are connected via the working channel. The first and second inlets are connected to a power supply unit.

[0009] The composite polyelectrolyte is disposed in the working channel; the two ends of the composite polyelectrolyte are p-type polyelectrolyte and n-type polyelectrolyte, respectively, and the two ends of the composite polyelectrolyte carry opposite charges; the middle part of the composite polyelectrolyte is an electrically neutral composite polyelectrolyte with a three-dimensional polymer structure formed by mixing p-type polyelectrolyte and n-type polyelectrolyte.

[0010] Furthermore, the first inlet, the first outlet, and the first main channel form a first electrolyte flow channel, and the second inlet, the second outlet, and the second main channel form a second electrolyte flow channel. The first electrolyte flow channel and the second electrolyte flow channel are symmetrical about the vertical axis of the working channel.

[0011] Furthermore, the height of the upper surface of the working channel is lower than the height of the upper surface of the first main channel, and the height of the upper surface of the first main channel is the same as the height of the upper surface of the second main channel.

[0012] Furthermore, the formation process of the composite polyelectrolyte is as follows:

[0013] p-type polyelectrolyte is added to the first injection port, n-type polyelectrolyte is added to the second injection port, and deionized water is added to the first and second outlet ports. Then, positive voltage is applied to the first injection port through the power supply unit, and the second injection port is grounded.

[0014] The power supply unit provides voltage to the first and second injection ports. An electric field is generated in the microfluidic chip, with the direction of the electric field pointing from the positive electrode to the negative electrode. Charged ions in the p-type polyelectrolyte and n-type polyelectrolyte are moved towards the opposite electrodes by the electric field force. During the movement, the ions collide with solvent molecules in the solution, thereby driving the solution to flow.

[0015] Because the working channel is lower than the first and second main channels, the solution itself has a pressure difference, which pushes the solution to flow into the working channel. In addition, the electric field and the capillary effect of the microchannel cause the p-type polyelectrolyte and the n-type polyelectrolyte to meet in the middle of the working channel.

[0016] Due to the electrostatic effect of polyelectrolytes, p-type and n-type electrolytes are immediately mixed to form a primary mixture. Subsequently, the original polymer chains change. Under the dominance of the interaction of hydrophobic groups in the polyelectrolyte chain segments, the macromolecules rearrange, and the complex chains tend to generate an ordered and regular structure, ultimately forming an electrically neutral composite polyelectrolyte with a three-dimensional polymer structure.

[0017] Furthermore, the width of the first main channel and the second main channel is 200μm and the height is 30μm; the width of the working channel is 20μm and the height is 5μm.

[0018] Furthermore, the first inlet, the second inlet, the first outlet, and the second outlet are cylindrical, and the diameter of the first inlet, the second inlet, the first outlet, and the second outlet is 6 mm.

[0019] This invention also provides a method for fabricating a polyelectrolyte ion diode with adjustable rectification ratio, which includes the following steps:

[0020] S1. Microfluidic chips are fabricated using soft photolithography.

[0021] S2. Use a punch to punch holes in the microfluidic chip to form a first sample inlet, a second sample inlet, a first sample outlet, and a second sample outlet, thereby modifying the surface of the microchannels in the microfluidic chip.

[0022] S3. Add p-type polyelectrolyte to the first injection port and n-type polyelectrolyte to the second injection port. Apply positive power to the first injection port through the power supply unit and ground the second injection port.

[0023] S4. Under the action of electric field, p-type polyelectrolyte and n-type polyelectrolyte meet in the working channel and immediately form a primary mixture after mixing. Subsequently, under the dominance of the interaction of hydrophobic groups in the polyelectrolyte chain segments, the macromolecules rearrange, and the complex chains tend to generate an ordered and regular structure, eventually forming an electrically neutral composite polyelectrolyte with a three-dimensional polymer structure, thereby forming a polyelectrolyte ion diode.

[0024] Furthermore, S1 specifically includes the following steps:

[0025] S11. Spin-coat photoresist onto the silicon wafer and pre-bake the silicon wafer coated with photoresist.

[0026] S12. Place the mask of the working channel on the pre-baked silicon wafer, then expose it under a UV lamp, bake the exposed silicon wafer again, and then soak and clean it in the developer solution.

[0027] S13. After cleaning and drying the silicon wafer, spin-coating of photoresist continues. After pre-baking, the mask of the main channel is placed on the silicon wafer and exposed under ultraviolet light.

[0028] S14. After baking, immerse and clean the silicon wafer in the developer solution, and after drying, wrap the silicon wafer with aluminum foil.

[0029] S15. Pour PDMS onto the silicon wafer and heat it in an oven at 80°C for 1 hour. After curing, the microfluidic chip can be obtained.

[0030] Furthermore, S2 specifically includes the following steps:

[0031] S21. Use a punch to punch holes in the cut microfluidic chip with a diameter of 6mm. Place the punched microfluidic chip and substrate into a plasma cleaner for 1 minute. Then bond the processed microfluidic chip and glass substrate together.

[0032] S22. Use a pipette to add deionized water to the inlet and outlet to rinse the channel; then remove the deionized water from the reservoir and continue to add 0.1M NaOH solution, soaking for 30 minutes; then rinse with clean water to remove any remaining NaOH from the channel.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] The present invention provides a polyelectrolyte ion diode with adjustable rectification ratio, and proposes a new method for preparing ion diodes. Under the action of pressure difference and electric field of solution, two solutions with opposite charges meet and react in the channel to form an ion diode with opposite charges at both ends. It has the advantages of simple preparation method and low cost.

[0035] The polyelectrolyte ion diode with adjustable rectification ratio provided by this invention requires less time and fewer fabrication steps to construct an ion diode. By changing the applied voltage, the rectification ratio of the ion diode can be precisely controlled. Compared with traditional ion diodes, the rectification ratio of this ion diode is simple to control.

[0036] The polyelectrolyte ion diode with adjustable rectification ratio provided by this invention has a small ion diode size and simple structure, which promotes its practical application in devices. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the ion diode of the present invention.

[0039] Figure 2 This is a schematic diagram of the composite polyelectrolyte structure of the present invention.

[0040] Figure 3 This is a micrograph of the composite polyelectrolyte region inside the polyelectrolyte ion diode of the present invention.

[0041] Figure 4 This is a system diagram for fabricating the ion diode of the present invention.

[0042] Figure 5 This is a schematic diagram of polyelectrolyte polymerization under the action of an electric field according to the present invention.

[0043] Figure 6 shows the current-voltage curves of the fabricated ion diodes under different electric field conditions in the voltage range of -10V to 10V. Figure 6a The electric field is 5V. Figure 6b The electric field is 30V.

[0044] Figure 7 This is a graph showing the change in the rectification ratio of the ion diode of the present invention as a function of the fabrication voltage.

[0045] In the figure: 1. Microfluidic chip; 2. First sample inlet; 3. Second sample inlet; 4. First sample outlet; 5. Second sample outlet; 6. First main channel; 7. Second main channel; 8. Working channel; 9. Power supply unit; 10. Substrate. Detailed Implementation

[0046] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0049] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0050] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0051] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways, rotated 90 degrees, or in other orientations, and the spatial relative descriptions used herein will be interpreted accordingly.

[0052] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0053] like Figure 1 As shown, the present invention provides a polyelectrolyte ion diode with adjustable rectification ratio, including a microfluidic chip 1 and a composite polyelectrolyte;

[0054] The microfluidic chip 1 is bonded to the substrate 10. The microfluidic chip 1 has a first inlet 2, a second inlet 3, a first outlet 4, and a second outlet 5 disposed through it. The microfluidic chip 1 is cuboid, and its upper surface is recessed downward to form a first main channel 6, a second main channel 7, and a working channel 8. The two ends of the first main channel 6 are connected to the first inlet 2 and the first outlet 4, respectively. The two ends of the second main channel 7 are connected to the second inlet 3 and the second outlet 5, respectively. The middle parts of the first main channel 6 and the second main channel 7 are connected through the working channel 8. The first inlet 2 and the second inlet 3 are connected to the power supply unit 9. The first inlet 2, the first outlet 4, and the first main channel 6 form a first electrolyte channel, and the second inlet 3, the second outlet 5, and the second main channel 7 form a second electrolyte channel. The first electrolyte channel and the second electrolyte channel are symmetrical about the vertical axis of the working channel 8. The height of the upper surface of the working channel 8 is lower than the height of the upper surface of the first main channel 6, and the height of the upper surface of the first main channel 6 is the same as the height of the upper surface of the second main channel 7.

[0055] The composite polyelectrolyte is disposed in the working channel 8; the two ends of the composite polyelectrolyte are p-type polyelectrolyte and n-type polyelectrolyte, respectively, and the two ends of the composite polyelectrolyte carry opposite charges. The middle part of the composite polyelectrolyte is an electrically neutral composite polyelectrolyte with a three-dimensional polymer structure formed by mixing p-type polyelectrolyte and n-type polyelectrolyte.

[0056] This invention also provides a method for preparing a polyelectrolyte ion diode with adjustable rectification ratio, comprising the following steps:

[0057] S1. Fabrication of three-dimensional microfluidic chips using soft photolithography.

[0058] S11. Spin-coat photoresist onto a silicon wafer and pre-bake the silicon wafer coated with photoresist.

[0059] S12. Place the mask of the working channel on the pre-baked silicon wafer, then expose it under a UV lamp, bake the exposed silicon wafer, and then soak and clean it in the developer solution.

[0060] S13. After the silicon wafer dries, spin-coating of photoresist continues. After pre-baking, the mask of the main channel is placed on the silicon wafer and exposed under ultraviolet light.

[0061] S14. After baking, immerse and clean the silicon wafer in the developer solution, and after drying, wrap the silicon wafer with aluminum foil.

[0062] S15. Pour PDMS onto the silicon wafer and heat it in an oven at 80°C for 1 hour. After curing, a three-dimensional microfluidic chip can be obtained.

[0063] S2. Use a punch to punch holes in the microfluidic chip, namely the inlet and outlet, to modify the surface of the microchannels of the microfluidic chip.

[0064] S3. Add p-type and n-type polyelectrolytes to the two injection ports of the microfluidic chip respectively, apply a positive charge to the first injection port, and ground the second injection port.

[0065] S4. Under the action of electric field, p-type and n-type polyelectrolytes meet in the working channel and immediately form a primary mixture after mixing. Subsequently, under the dominance of the interaction of hydrophobic groups in the polyelectrolyte chain segments, the macromolecules rearrange, and the complex chains tend to generate an ordered and regular structure, eventually forming an electrically neutral composite polyelectrolyte with a three-dimensional polymer structure, thereby forming a polyelectrolyte ion diode.

[0066] Example 1

[0067] A polyelectrolyte ion diode with adjustable rectification ratio is mainly composed of a three-dimensional microfluidic chip and a composite polyelectrolyte. The microfluidic chip is bonded to a glass substrate 10 and mainly consists of a microfluidic chip 1, a first sample inlet 2, a second sample inlet 3, a first sample outlet 4 and a second sample outlet 5, a first main channel 6, a second main channel 7, and a working channel 8. The three-dimensional microfluidic chip is a cuboid with a length of 5 cm, a width of 3.5 cm, and a height of 0.5 cm. The first main channel 6 and the second main channel 7 are symmetrically distributed and connected by the working channel 8. In the vertical direction, the working channel 8 is lower than the main channel. The two main channels have a width of 200 μm and a height of 30 μm, while the working channel has a width of 20 μm and a height of 5 μm. The first main channel 6 and the second main channel 7 have sample inlets and outlets at their ends, respectively, penetrate the microfluidic chip, have a diameter of 6 mm, and communicate with the main channels. The composite polyelectrolyte is located in the working channel 8.

[0068] In specific implementation, as a preferred embodiment of the present invention, such as Figure 2 and Figure 3 As shown, Figure 2 This is a schematic diagram of the composite polyelectrolyte structure of the present invention. Figure 3 This is a micrograph of the composite polyelectrolyte region inside the polyelectrolyte ion diode of the present invention. The two ends of the composite polyelectrolyte of the present invention are p-type polyelectrolyte and n-type polyelectrolyte, respectively, with opposite charges at both ends. The middle part is an electrically neutral composite polyelectrolyte with a three-dimensional polymer structure formed by mixing p-type polyelectrolyte and n-type polyelectrolyte.

[0069] In specific implementation, as a preferred embodiment of the present invention, such as Figure 4 As shown, a quantitative amount of p-type polyelectrolyte is added to the first injection port 2, a quantitative amount of n-type polyelectrolyte is added to the second injection port 3, and a quantitative amount of deionized water is added to the first outlet port 4 and the second outlet port 5. Then, a positive voltage is applied to the first injection port 2, the second injection port 3 is grounded, and the power supply unit 6 is used to provide voltage.

[0070] In a preferred embodiment of the present invention, the concentration of the polyelectrolyte solution used in the experiment is 0.5%–2.5%, the amount of polyelectrolyte added in each experiment is 60 μL, and the amount of deionized water added is 30 μL.

[0071] In specific implementation, as a preferred embodiment of the present invention, such as Figure 5As shown, after the power supply unit 6 provides voltage, an electric field is generated in the microchannel. The direction of the electric field is from the positive electrode to the negative electrode. Under a certain electric field strength, the charged ions in the polyelectrolyte solution will be affected by the electric field force and move towards the opposite electrode. During the movement, the ions collide with the solvent molecules in the solution, thereby driving the solution to flow. Since the working channel 8 is lower than the main channel, the solution itself has a certain pressure difference, which pushes the solution to flow towards the working channel 8. In addition, the electric field and the capillary effect of the microchannel cause the p-type polyelectrolyte and n-type polyelectrolyte to meet in the middle of the working channel. Due to the electrostatic effect of the polyelectrolyte, the p-type and n-type electrolytes immediately form a primary mixture after mixing within 10-20 seconds. After another 1-2 hours, the original polymer chains change. Subsequently, under the dominance of the interaction of hydrophobic groups in the polyelectrolyte chain segments, the macromolecules rearrange, and the complex chains tend to generate an ordered and regular structure, finally forming an electrically neutral composite polyelectrolyte with a three-dimensional polymer structure, thus obtaining a polyelectrolyte ion diode with opposite charges at both ends.

[0072] In specific implementation, as a preferred embodiment of the present invention, as shown in Figure 6 and... Figure 7 As shown in Figure 6, the current-voltage curves of the ion diode were measured at voltages of 5V and 30V. In the IV curve, the rectification ratio at an applied voltage of 30V is greater than that at an applied voltage of 5V. Figure 7 This is a graph showing the rectification ratio of the ion diode of the present invention as a function of fabrication voltage. Figure 7 It can be seen that as the voltage increases, the rectification ratio of the ion diode increases accordingly.

[0073] Example 2

[0074] A method for fabricating a polyelectrolyte ion diode with adjustable rectification ratio, the method comprising the following steps:

[0075] (1) The steps for fabricating the microfluidic chip are as follows:

[0076] The mask for this invention was customized by a third-party company. The mask has two patterns: one for the main channels 6 and 7, and one for the working channel 8. The microfluidic chip is fabricated using existing microfabrication techniques.

[0077] Silicon wafers pre-baked with photoresist;

[0078] Place the mask of working channel 8 on the pre-baked silicon wafer and expose it under a UV lamp, then bake the exposed silicon wafer again.

[0079] After the silicon wafer cools, photoresist is spin-coated, followed by pre-baking. After pre-baking, the masks for working channels 6 and 7 are placed and observed under a microscope. Working channel 8 is perpendicular to the two main channels 6 and 7. The two main channels 6 and 7 are connected in the middle and exposed under a UV lamp. The exposed silicon wafer is then post-baked.

[0080] After baking, immerse the silicon wafer in the developer solution and clean it. After drying, wrap it with aluminum foil around the edges.

[0081] PDMS is poured onto a silicon wafer and heated in an oven at 80°C for 1 hour to cure the PDMS. The cured PDMS is then cut to obtain a microfluidic chip.

[0082] (2) Modification of microchannels in three-dimensional microfluidic chips:

[0083] a. Use a punch to punch holes in the cut microfluidic chip with a diameter of 6 mm. The inlet and outlet are located at the beginning and end of the two main channels 3 and 4, respectively. Place the punched microfluidic chip and glass substrate 10 into a plasma cleaner for 1 minute. Then bond the processed microfluidic chip and glass substrate 10 together.

[0084] b. Use a pipette to add deionized water to the reservoir to flush the channel; then remove the deionized water from the reservoir and continue to add 0.1M NaOH solution, soaking for 30 minutes; then rinse with clean water to remove any remaining NaOH from the channel.

[0085] (3) Generation of polyelectrolyte ion diodes

[0086] a. The modified microfluidic chip has a certain amount of deionized water added to reservoirs 4 and 5, a certain amount of p-type polyelectrolyte added to reservoir 2, and a certain amount of n-type polyelectrolyte added to reservoir 3.

[0087] b. Apply positive voltage to the first injection port 2, ground the second injection port 3, apply voltage to it by the power supply unit, and the p-type polyelectrolyte and n-type polyelectrolyte meet in the working channel 8 to generate a polyelectrolyte ion diode.

[0088] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polyelectrolyte ion diode with adjustable rectification ratio, characterized in that: Includes a microfluidic chip (1) and a composite polyelectrolyte; The microfluidic chip (1) is bonded to the substrate (10). The microfluidic chip (1) has a first inlet (2), a second inlet (3), a first outlet (4), and a second outlet (5) through it. The microfluidic chip (1) is a cuboid. The upper surface of the microfluidic chip (1) is recessed downward to form a first main channel (6), a second main channel (7), and a working channel (8). The two ends of the first main channel (6) are connected to the first inlet (2) and the first outlet (4), respectively. The two ends of the second main channel (7) are connected to the second inlet (3) and the second outlet (5), respectively. The middle part of the first main channel (6) and the middle part of the second main channel (7) are connected through the working channel (8). The first inlet (2) and the second inlet (3) are connected to the power supply unit (9). The composite polyelectrolyte is disposed in the working channel (8); the two ends of the composite polyelectrolyte are p-type polyelectrolyte and n-type polyelectrolyte, respectively, and the two ends of the composite polyelectrolyte carry opposite charges. The middle part of the composite polyelectrolyte is an electrically neutral composite polyelectrolyte with a three-dimensional polymer structure formed by mixing p-type polyelectrolyte and n-type polyelectrolyte. The height of the upper surface of the working channel (8) is lower than the height of the upper surface of the first main channel (6), and the height of the upper surface of the first main channel (6) is the same as the height of the upper surface of the second main channel (7). The formation process of the composite polyelectrolyte is as follows: p-type polyelectrolyte is added to the first injection port (2), n-type polyelectrolyte is added to the second injection port (3), deionized water is added to the first outlet port (4) and the second outlet port (5), and then positive electricity is applied to the first injection port (2) through the power supply unit (9), and the second injection port (3) is grounded; The power supply unit (9) provides voltage to the first injection port (2) and the second injection port (3). An electric field is generated in the microfluidic chip (1). The direction of the electric field is from the positive electrode to the negative electrode. Charged ions in the p-type polyelectrolyte and n-type polyelectrolyte are moved towards the opposite electrode by the electric field force. During the movement, the ions collide with solvent molecules in the solution, thereby driving the solution to flow. Since the working channel (8) is lower than the first main channel (6) and the second main channel (7), the solution itself has a pressure difference, which pushes the solution to flow into the working channel (8). In addition, the electric field and the capillary effect of the microchannel cause the p-type polyelectrolyte and the n-type polyelectrolyte to meet in the middle of the working channel (8). Due to the electrostatic interaction of polyelectrolytes, p-type and n-type electrolytes immediately form a primary mixture after mixing. Subsequently, the original polymer chains change. Under the dominance of the hydrophobic groups of the polyelectrolyte chain segments, the macromolecules rearrange, and the complex chains tend to generate an ordered and regular structure, ultimately forming an electrically neutral composite polyelectrolyte with a three-dimensional polymer structure.

2. The polyelectrolyte ion diode with adjustable rectification ratio according to claim 1, characterized in that, The first inlet (2), the first outlet (4) and the first main channel (6) form the first electrolyte flow channel, and the second inlet (3), the second outlet (5) and the second main channel (7) form the second electrolyte flow channel. The first electrolyte flow channel and the second electrolyte flow channel are symmetrical about the vertical axis of the working channel (8).

3. The polyelectrolyte ion diode with adjustable rectification ratio according to claim 1, characterized in that, The width of the first main channel (6) and the second main channel (7) is 200 μm and the height is 30 μm; the width of the working channel (8) is 20 μm and the height is 5 μm.

4. The polyelectrolyte ion diode with adjustable rectification ratio according to claim 1, characterized in that, The first inlet (2), the second inlet (3), the first outlet (4) and the second outlet (5) are cylindrical, and the diameter of the first inlet (2), the second inlet (3), the first outlet (4) and the second outlet (5) is 6 mm.

5. A method for fabricating a polyelectrolyte ion diode with adjustable rectification ratio, used to fabricate the polyelectrolyte ion diode with adjustable rectification ratio as described in any one of claims 1-4, characterized in that, Includes the following steps: S1. Microfluidic chips are fabricated using soft photolithography (1). S2. Use a punch to punch holes in the microfluidic chip (1) to form a first sample inlet (2), a second sample inlet (3), a first sample outlet (4), and a second sample outlet (5), and perform surface modification on the microchannels of the microfluidic chip (1); S3. Add p-type polyelectrolyte to the first injection port (2) and n-type polyelectrolyte to the second injection port (3). Apply positive power to the first injection port (2) through the power supply unit (9) and ground the second injection port (3). S4. Under the action of electric field force, p-type polyelectrolyte and n-type polyelectrolyte meet in working channel (8) and immediately form a primary mixture after mixing. Subsequently, under the dominance of the interaction of hydrophobic groups in the polyelectrolyte chain segments, the macromolecules rearrange, and the complex chain tends to generate an ordered and regular structure, eventually forming an electrically neutral composite polyelectrolyte with a three-dimensional polymer structure, thereby forming a polyelectrolyte ion diode.

6. The method for preparing a polyelectrolyte ion diode with adjustable rectification ratio according to claim 5, characterized in that, S1 specifically includes the following steps: S11. Spin-coat photoresist onto the silicon wafer and pre-bake the silicon wafer coated with photoresist. S12. Place the mask of the working channel (8) on the pre-baked silicon wafer, then expose it under a UV lamp, bake the exposed silicon wafer, and then soak and clean it in the developer solution. S13. After cleaning and drying the silicon wafer, spin-coating of photoresist continues. After pre-baking, the mask of the main channel is placed on the silicon wafer and exposed under ultraviolet light. S14. After baking, immerse and clean the silicon wafer in the developer solution, and after drying, wrap the silicon wafer with aluminum foil. S15. Pour PDMS onto the silicon wafer and heat it in an oven at 80°C for 1 hour. After curing, the microfluidic chip (1) can be obtained.

7. The method for preparing a polyelectrolyte ion diode with adjustable rectification ratio according to claim 5, characterized in that, S2 specifically includes the following steps: S21. Use a punch to punch holes in the cut microfluidic chip (1) with a hole diameter of 6mm. Put the punched microfluidic chip (1) and substrate (10) into a plasma cleaner for 1 minute and bond the processed microfluidic chip (1) and substrate (10). S22. Use a pipette to add deionized water to the inlet and outlet to rinse the channel; then remove the deionized water from the reservoir and continue to add 0.1M NaOH solution, soaking for 30 minutes; then rinse with clean water to remove any remaining NaOH from the channel.

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