Micro LED fluid assembly method based on microfluidics and dielectrophoresis

Abstract

The invention discloses a micro-fluidic and dielectrophoresis-based Mi cro LED (Light Emitting Diode) fluid assembly method. The method comprises the following steps of S1, manufacturing a Mi cro LED chip into a Mi cro LED chip hydrogel microsphere; s2, the Mi cro LED chip hydrogel microspheres are placed in the liquid in a suspended mode; s3, the Mi cro LED chip hydrogel microspheres with the performance meeting the requirements are sorted out; s4, the hydrogel microspheres of the Mi cro LED chip are evenly distributed on a target substrate, and then a dielectrophoresis trap is used for assembling; s5, a dielectrophoresis trap prepared on the target substrate successively captures the hydrogel microspheres of the Mi cro LED chip, and a large-scale ordered array is formed; and S6, releasing the Mi cro LED chips wrapped by the Mi cro LED chip hydrogel microspheres, so as to obtain the corresponding Mi cro LED chip array. According to the invention, accurate positioning and control of the Mi cro LED hydrogel microspheres are realized, high-precision transfer of the Mi cro LED chip is completed, the transfer efficiency and positioning precision of the Mi cro LED are improved, the transfer process of the Mi cro LED is simplified, the production cost is reduced, and the Mi cro LED hydrogel microspheres have a wide market application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field related to mass transfer, and in particular to a MicroLED fluid assembly method based on microfluidics and dielectrophoresis. Background Art

[0002] As we all know, the key technology to realize Micro LED display screens is mass transfer; how to significantly reduce the transfer cost of Micro LED has become the focus of the industry; self-assembly technology, as a parallel manufacturing technology, has proposed research on the principles of fluid force, surface energy, magnetism, gravity, electrostatic force, etc. The self-assembly technology applied to Micro LED mass transfer refers to directional self-assembly technology, which uses the following steps: placing a large number of micro components in the system, using a certain force to make the chip move quickly at a certain speed, and completing the alignment assembly method with the corresponding assembly position of the substrate by itself.

[0003] Currently, the two most representative self-assembly technologies in the industry are magnetic self-assembly and fluid self-assembly technology.

[0004] Fluid assembly technology has the advantages of low machine cost, low process cost, low material cost, etc., and the random process has no light spot or color spot problems.

[0005] Fluid assembly technology mainly allows the substrate structure to capture Micro LED chips at a precise position, while creating multiple capture opportunities through reciprocating flow. It uses a self-assembly process, does not require external precise alignment, and is independent of the number of pixels. The LED spacing is also not limited by the accuracy of the assembly machine, so the cost is very low; the harvested μLEDs are randomly mixed in the liquid, and defective chips can be detected by micro-PL during the chip process and excluded in the harvesting process, allowing nearly 100% of the chips to be effectively utilized.

[0006] Dielectrophoresis refers to an effect in which neutral particles are subjected to forces under the action of a non-uniform electric field. When a particle suspended in a liquid medium is subjected to a non-uniform electric field, it may be forced to move toward an area with a stronger electric field (positive dielectrophoresis) or toward an area with a weaker electric field (negative dielectrophoresis). Unlike electrophoresis, particles subjected to dielectrophoretic forces do not necessarily need to be charged, and dielectrophoretic forces are insensitive to the polarity of the electric field. Both direct current and alternating current can be used to produce the dielectrophoretic effect. All particles will have a certain degree of dielectrophoretic effect under the action of a non-uniform electric field, and the strength of the dielectrophoretic force is related to the size and shape of the particles, the electrical properties of the particles and the medium, and the frequency of the electric field. Due to its ease of operation, the frequency of the electric field is often used as an adjustment parameter for controlling different particles in the liquid.

[0007] In the field of Micro LED mass transfer, dielectrophoresis technology is expected to be widely used; dielectrophoresis is an effect that uses non-uniform electric fields to exert force on neutral particles without the need for the particles to be charged. Under this technology, Micro LEDs can be precisely controlled and transferred, thereby achieving efficient production and application.

[0008] Dielectrophoresis technology has the following advantages and characteristics for the mass transfer of Micro LEDs:

[0009] 1. Precise control: By adjusting the electric field parameters, the position and movement trajectory of Micro LED can be precisely controlled to achieve highly accurate transfer;

[0010] 2. Efficient transfer: Dielectrophoresis technology can realize the simultaneous processing and transfer of a large number of Micro LEDs, improving production efficiency;

[0011] 3. Non-destructive: Since the dielectrophoretic force does not require the particles to be charged, it will not cause damage to the Micro LED, thus ensuring its quality and performance;

[0012] 4. Easy to operate: Dielectrophoresis technology is easy to operate and can control different particles by adjusting the frequency and intensity of the electric field. It is suitable for production scenarios of different scales.

[0013] In general, dielectrophoresis technology will play an important role in Micro LED mass transfer, providing technical support for efficient and precise production and application.

[0014] Microfluidics is a technology that can precisely control and manipulate microscale fluids, especially submicron structures. It is also called Lab-on-a-Chip or microfluidic chip technology. It integrates the basic operating units of biological, chemical, and medical analysis processes such as sample preparation, reaction, separation, and detection into a micron-scale chip to automatically complete the entire analysis process.

[0015] Two immiscible liquids, one of which is used as the continuous phase and the other as the dispersed phase. The dispersed phase is dispersed in the continuous phase in the form of small volume units to form droplets. In the field of microfluidics, passive methods are mainly used to prepare droplets. The three commonly used methods are as follows:

[0016] Flow focusing method: In the flow focusing method, three flow paths are focused into one pipe, and the dispersed phase and the mobile phase converge at the cross tube. The upper and lower symmetrical flow phases squeeze the dispersed phase at the same time to break it, thus forming droplets.

[0017] Co-flow focusing method: In the coaxial flow focusing method, a capillary with a pointed tip is inserted into the central axis of the channel, and the dispersed phase and the continuous phase flow in parallel in the channel. When the dispersed phase enters the continuous phase channel, it is squeezed and broken to form droplets under the shear force of the continuous phase fluid.

[0018] T-channel method: In the T-channel method, two immiscible fluids meet at the intersection of a vertical T-shaped pipe. Under the action of pressure and shear force, the mobile phase cuts off the dispersed phase to form droplets.

[0019] Based on microfluidics and dielectrophoresis technology, a Micro LED fluid assembly method based on microfluidics and dielectrophoresis was proposed. Summary of the invention

[0020] The purpose of the present invention is to provide a Micro LED fluid assembly method based on microfluidics and dielectrophoresis, which improves the transfer efficiency and positioning accuracy of the Micro LED chip, simplifies the Micro LED transfer process, and reduces the production cost.

[0021] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0022] A Micro LED fluid assembly method based on microfluidics and dielectrophoresis comprises the following steps:

[0023] S1: After laser peeling, the Micro LED chip is mixed into liquid, and the co-flow focusing method in microfluidics is used to make the Micro LED chip into independent Micro LED chip hydrogel microspheres wrapped by hydrogel.

[0024] S2: Suspending the Micro LED chip hydrogel microspheres made of Micro LED chips in a commonly used liquid;

[0025] S3: Use the corresponding PL detection equipment to test the Micro LED chip in a single Micro LED chip hydrogel microsphere, and sort out the Micro LED chip hydrogel microspheres that meet the performance requirements after the test;

[0026] S4: Use fluid force to drive the selected Micro LED chip hydrogel microspheres that meet the requirements to be evenly distributed on the target substrate, and then use dielectrophoresis traps to capture the Micro LED chip hydrogel microspheres for assembly;

[0027] S5: After the Micro LED chip hydrogel microspheres in the fluid are pushed to circulate on the surface of the substrate, the dielectrophoresis trap current switch is turned on, and the dielectrophoresis traps prepared on the target substrate successively capture the Micro LED chip hydrogel microspheres to form a large-scale ordered array;

[0028] S6: After the assembly is completed, the excess Micro LED chip hydrogel microspheres are taken away by a clean fluid, the ordered array of Micro LED chip hydrogel microspheres are dissolved or decomposed, and the Micro LED chips wrapped in the Micro LED chip hydrogel microspheres are released, which is the corresponding Micro LED chip array.

[0029] In a preferred solution, in step S2, the commonly used liquid is water or physiological saline.

[0030] In a preferred embodiment, in step S4, the single electrode structure of the dielectrophoretic trap is as follows: the trap or cage consists of a single metal ring electrode, driven by an AC signal and separated by a uniform gap from the surrounding ground plane, a high field is located in the gap between the two electrodes, and there is a minimum field at the center of the ring electrode, thereby generating a negative dielectrophoretic trap.

[0031] In a preferred solution, in step S4, the annular electrode ensures that the field minimum is three-dimensional and the dielectrophoresis trap is closed in the vertical direction.

[0032] In a preferred embodiment, the dielectrophoretic trap is manufactured using photolithography technology, and an interlayer dielectric insulator is provided between two metal ring electrodes.

[0033] In a preferred solution, in step S5, a bubble pump is used to circulate the liquid containing the Micro LED chip hydrogel microspheres.

[0034] In a preferred solution, in step S6, the Micro LED chip hydrogel microspheres are dissolved or decomposed by heating or adding a corresponding solvent to the fluid.

[0035] Due to the application of the above technical solution, the beneficial effects of the present application compared with the prior art are:

[0036] The present application provides a Micro LED fluid assembly method based on microfluidics and dielectrophoresis. The method uses microfluidics technology to wrap the hydrogel with Micro LED and uses the dielectrophoresis trap array on the substrate to capture the Micro LED hydrogel microspheres. A layer of hydrogel is wrapped on the surface of the Micro LED, and then the hydrogel particles are captured at a specific position of the target substrate through the electric field effect of the dielectrophoresis trap array. By adjusting the electric field parameters, the Micro LED hydrogel microspheres are precisely positioned and controlled, and the high-precision transfer of the Micro LED chip is completed, which improves the transfer efficiency and positioning accuracy of the Micro LED, simplifies the Micro LED transfer process, reduces the production cost, and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0038] Figure 1 Schematic diagram of the process of the Micro LED fluid assembly method based on microfluidics and dielectrophoresis of the present invention;

[0039] Figure 2 is a schematic diagram of the dielectrophoresis trap structure of the present invention;

[0040] Among them, 1. Pt; 2. Dielectric layer; 3. Glass. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present application.

[0042] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0043] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0044] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0045] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0047] Embodiment 1

[0048] See also Figure 1 and Figure 2 The present application provides a Micro LED fluid assembly method based on microfluidics and dielectrophoresis, comprising the following steps:

[0049] S1: After laser peeling, the Micro LED chips are mixed into liquid, and the co-flow focusing method in microfluidics is used to make the Micro LED chips into independent Micro LED chip hydrogel microspheres wrapped by hydrogel. Since the Micro LED chips are wrapped by hydrogel, the damage caused by collision between Micro LED chips can be avoided in the subsequent Micro LED chip assembly process.

[0050] S2: Suspend the Micro LED chip hydrogel microspheres made of Micro LED chips in a common liquid, such as water or saline;

[0051] S3: Use the corresponding PL detection equipment to test the Micro LED chip in a single Micro LED chip hydrogel microsphere, and sort out the Micro LED chip hydrogel microspheres that meet the performance requirements after the test;

[0052] S4: Use fluid force to drive the selected Micro LED chip hydrogel microspheres that meet the requirements to be evenly distributed on the target substrate, and then use dielectrophoresis trap to capture the Micro LED chips. LED chip hydrogel microspheres are assembled; the single electrode structure of the dielectrophoresis trap is: the trap or cage consists of a single metal ring electrode, driven by an AC signal and separated by a uniform gap from the surrounding ground plane, the high field is located at the gap between the two electrodes, and there is a minimum field at the center of the ring electrode, thereby generating a negative dielectrophoresis trap; the ring electrode ensures that the field minimum is three-dimensional and the dielectrophoresis trap is closed in the vertical direction; the dielectrophoresis trap is manufactured using photolithography technology, and an interlayer dielectric insulator is provided between the two metal ring electrodes; the electrode structure of the dielectrophoresis trap is prepared at the corresponding position of the entire target substrate as required; the specific dielectrophoresis trap structure includes Pt1, a dielectric layer 2 and a glass 3, and the dielectric layer 2 is arranged between the Pt1 and the glass 3; the Pt1 is arranged at the upper end of the dielectric layer 2, and the glass 3 is arranged at the lower end of the dielectric layer 2; of the two ring electrodes, the smaller ring electrode has an inner diameter of 80μm and an outer diameter of 100μm; the larger ring electrode has an inner diameter of 100μm and an outer diameter of 120μm;

[0053] S5: When the Micro LED chip hydrogel microspheres in the fluid are pushed by the bubble pump to circulate on the surface of the substrate, the dielectrophoresis trap current switch is turned on, and the dielectrophoresis traps prepared on the target substrate capture the Micro LED chip hydrogel microspheres one after another, forming a large-scale ordered array;

[0054] S6: After the assembly is completed, the excess Micro LED chip hydrogel microspheres are taken away by a clean fluid, and the ordered array of Micro LED chip hydrogel microspheres are dissolved or decomposed by heating or adding corresponding solvents to the fluid to release the Micro LED chip wrapped by the Micro LED chip hydrogel microspheres, which is the corresponding Micro LED chip array.

[0055] The present application provides a Micro LED fluid assembly method based on microfluidics and dielectrophoresis. The method uses microfluidics technology to wrap the hydrogel with Micro LED and uses the dielectrophoresis trap array on the substrate to capture the Micro LED hydrogel microspheres. A layer of hydrogel is wrapped on the surface of the Micro LED, and then the hydrogel particles are captured at a specific position of the target substrate through the electric field effect of the dielectrophoresis trap array. By adjusting the electric field parameters, the Micro LED hydrogel microspheres are precisely positioned and controlled, and the high-precision transfer of the Micro LED chip is completed, which improves the transfer efficiency and positioning accuracy of the Micro LED, simplifies the Micro LED transfer process, reduces the production cost, and has broad market application prospects.

[0056] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A Micro LED fluid assembly method based on microfluidics and dielectrophoresis, characterized in that: The steps include: S1: After laser peeling, the Micro LED chip is mixed into liquid, and the co-flow focusing method in microfluidics is used to make the Micro LED chip into independent Micro LED chip hydrogel microspheres wrapped by hydrogel. S2: Suspending the Micro LED chip hydrogel microspheres made of Micro LED chips in a commonly used liquid; S3: Use the corresponding PL detection equipment to test the Micro LED chip in a single Micro LED chip hydrogel microsphere, and sort out the Micro LED chip hydrogel microspheres that meet the performance requirements after the test; S4: Use fluid force to drive the selected Micro LED chip hydrogel microspheres that meet the requirements to be evenly distributed on the target substrate, and then use dielectrophoresis traps to capture the Micro LED chip hydrogel microspheres for assembly; S5: After the Micro LED chip hydrogel microspheres in the fluid are pushed to circulate on the surface of the substrate, the dielectrophoresis trap current switch is turned on, and the dielectrophoresis traps prepared on the target substrate successively capture the Micro LED chip hydrogel microspheres to form a large-scale ordered array; S6: After the assembly is completed, the excess Micro LED chip hydrogel microspheres are taken away by a clean fluid, the ordered array of Micro LED chip hydrogel microspheres are dissolved or decomposed, and the Micro LED chips wrapped in the Micro LED chip hydrogel microspheres are released, which is the corresponding Micro LED chip array.

2. The Micro LED fluid assembly method based on microfluidics and dielectrophoresis according to claim 1, characterized in that: In step S2, the commonly used liquid is water or physiological saline.

3. The Micro LED fluid assembly method based on microfluidics and dielectrophoresis according to claim 1, characterized in that: In step S4, a single electrode structure of the dielectrophoretic trap is as follows: the trap or cage consists of a single metal ring electrode, driven by an AC signal and separated by a uniform gap from the surrounding ground plane, with a high field located at the gap between the two electrodes and a minimum field at the center of the ring electrode, thereby generating a negative dielectrophoretic trap.

4. The Micro LED fluid assembly method based on microfluidics and dielectrophoresis as claimed in claim 3, characterized in that: In step S4, the annular electrodes ensure that the field minimum is three-dimensional and the dielectrophoretic trap is closed in the vertical direction.

5. The Micro LED fluid assembly method based on microfluidics and dielectrophoresis as claimed in claim 4, characterized in that: The dielectrophoretic trap was fabricated using photolithography and had an interlayer dielectric insulator between two metal ring electrodes.

6. The Micro LED fluid assembly method based on microfluidics and dielectrophoresis according to claim 1, characterized in that: In step S5, a bubble pump is used to circulate the liquid containing the Micro LED chip hydrogel microspheres.

7. The Micro LED fluid assembly method based on microfluidics and dielectrophoresis according to claim 1, characterized in that: In step S6, the Micro LED chip hydrogel microspheres are dissolved or decomposed by heating or adding a corresponding solvent to the fluid.

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