A Micro LED fluid assembly method based on microfluidics and dielectrophoresis

Abstract

The present application discloses a Micro LED fluid assembly method based on microfluidics and dielectrophoresis, comprising the following steps: S1: making the Micro LED chip into Micro LED chip hydrogel microspheres; S2: suspending the Micro LED chip hydrogel microspheres in a liquid; S3: sorting out the Micro LED chip hydrogel microspheres that meet the performance requirements; S4: evenly distributing the Micro LED chip hydrogel microspheres on the target substrate, and then assembling them using dielectrophoresis traps; S5: the dielectrophoresis traps prepared on the target substrate successively capture the Micro LED chip hydrogel microspheres to form a large-scale ordered array; S6: releasing the Micro LED chip wrapped in the Micro LED chip hydrogel microspheres, which is the corresponding Micro LED chip array; the present application realizes the precise positioning and control of the Micro LED hydrogel microspheres, completes the high-precision transfer of the Micro LED chip, 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.

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 principles such as fluid force, surface energy, magnetism, gravity, and electrostatic force. The self-assembly technology applied to Micro LED mass transfer refers to directed self-assembly technology, which adopts 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 problem.

[0005] Fluidic assembly technology primarily allows the substrate structure to capture Micro LED chips at precise locations, while creating multiple capture opportunities through reciprocating flow. Using a self-assembly process, it requires no external precision alignment and is independent of the number of pixels. The spacing between LEDs is also not limited by the precision of the assembly machine, resulting in very low costs. Harvested μLEDs are randomly mixed in the liquid, and defective chips can be detected by the micro-PL during the chip manufacturing process and eliminated during the harvesting process, allowing for nearly 100% efficient chip utilization.

[0006] Dielectrophoresis refers to the effect of forces acting on neutral particles 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 areas with stronger electric fields (positive dielectrophoresis) or toward areas with weaker electric fields (negative dielectrophoresis). Unlike electrophoresis, particles subjected to dielectrophoretic forces do not necessarily need to be charged, and the dielectrophoretic force is 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 experience 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 a regulating parameter to control 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 a non-uniform electric field to exert force on neutral particles without the need for the particles to be charged. With 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 mass transfer of Micro LEDs:

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

[0010] 2. Efficient transfer: Dielectrophoresis technology can simultaneously process and transfer a large number of Micro LEDs, improving production efficiency;

[0011] 3. Non-destructive: Since the dielectrophoretic force does not require charging of particles, it will not damage 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 the mass transfer of Micro LEDs, providing technical support for efficient and precise production and applications.

[0014] Microfluidics is a technology for precisely controlling and manipulating microscale fluids, particularly submicron structures. It is also known as Lab-on-a-Chip or microfluidic chip technology. It integrates the basic operational units of biological, chemical, and medical analysis processes, such as sample preparation, reaction, separation, and detection, onto a micron-scale chip, automatically completing the entire analysis process.

[0015] Two immiscible liquids are prepared, with one as the continuous phase and the other as the dispersed phase. The dispersed phase is dispersed in the continuous phase in the form of tiny 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 pipe. The upper and lower symmetrical flow phases squeeze the dispersed phase at the same time to break it, thereby 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 parallel to each other in the channel. When the dispersed phase enters the continuous phase channel, it is squeezed and broken into 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 intercepts the dispersed phase, thus forming 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 Micro LED chips, simplifies the Micro LED transfer process, and reduces production costs.

[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 includes the following steps:

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

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

[0025] S3: Use corresponding PL testing 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: Using fluid force to evenly distribute the selected Micro LED chip hydrogel microspheres that meet the requirements onto the target substrate, and then using 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 substrate surface, the dielectrophoresis trap current switch is turned on. The dielectrophoresis traps prepared on the target substrate gradually capture the Micro LED chip hydrogel microspheres, forming a large-scale ordered array.

[0028] S6: After assembly is completed, the excess Micro LED chip hydrogel microspheres are removed by a clean fluid, and the ordered array of Micro LED chip hydrogel microspheres is dissolved or decomposed to release the Micro LED chips wrapped in the Micro LED chip hydrogel microspheres, 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, with a high field located in the gap between the two electrodes and 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 dielectrophoretic trap is closed in the vertical direction.

[0032] In a preferred embodiment, the dielectrophoretic trap is manufactured using a photolithography technique, and an interlayer dielectric insulator is provided between the 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 hydrogel microspheres of the Micro LED chip 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 this application compared with the prior art are:

[0036] The present application provides a Micro LED fluid assembly method based on microfluidics and dielectrophoresis. By utilizing microfluidics technology to wrap hydrogel around Micro LEDs and utilizing a dielectrophoresis trap array on a substrate to capture Micro LED hydrogel microspheres, a layer of hydrogel is wrapped around the surface of the Micro LED. The electric field effect of the dielectrophoresis trap array is then used to capture the hydrogel particles at specific positions on the target substrate. By adjusting the electric field parameters, precise positioning and control of the Micro LED hydrogel microspheres are achieved, completing high-precision transfer of the Micro LED chip. This improves the transfer efficiency and positioning accuracy of the Micro LED, simplifies the Micro LED transfer process, reduces production costs, and has broad market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any 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 present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of this 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 that includes 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 this application, terms such as "upper," "lower," "left," "right," "front," "back," "top," "bottom," "inner," "outer," "center," "vertical," "horizontal," "transverse," and "longitudinal" indicate positions or locations based on the positions or locations shown in the accompanying drawings. These terms are primarily intended to better describe the present invention and its embodiments and are not intended to limit the devices, elements, or components indicated to having a specific orientation, or to being constructed or operated in a specific orientation.

[0044] Furthermore, some of the above terms may be used to express other meanings besides indicating a position or location. For example, the term "on" may also be used to indicate a dependency or connection in certain circumstances. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0045] Furthermore, the terms "installed," "disposed," "provided with," "connected," "connected," and "socketed" should be interpreted broadly. For example, they can refer to fixed connections, removable connections, or integral structures; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; or internal communication between two devices, elements, or components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0046] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this 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] Example 1

[0048] See 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 lift-off, the Micro LED chips are mixed into a liquid. Using the co-flow focusing method in microfluidics, the Micro LED chips are fabricated into individual hydrogel-encapsulated Micro LED chip hydrogel microspheres. Because the Micro LED chips are encapsulated in hydrogel, damage caused by collisions between Micro LED chips during subsequent assembly can be avoided.

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

[0051] S3: Use corresponding PL testing 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 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, the 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; the ring electrode ensures that the field minimum is three-dimensional and the dielectrophoretic trap is closed in the vertical direction; the dielectrophoretic trap is manufactured using photolithography technology, and an interlayer dielectric insulator is provided between the two metal ring electrodes; the electrode structure of the dielectrophoretic trap is prepared at the corresponding position on the entire target substrate as required; the specific dielectrophoretic trap structure includes Pt1, a dielectric layer 2 and glass 3, 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: After the Micro LED chip hydrogel microspheres in the fluid are pushed by the bubble pump to circulate on the substrate surface, the dielectrophoresis trap current switch is turned on. The dielectrophoresis traps prepared on the target substrate gradually capture the Micro LED chip hydrogel microspheres, forming a large-scale ordered array.

[0054] S6: After assembly is completed, excess Micro LED chip hydrogel microspheres are removed by a clean fluid, and the ordered array of Micro LED chip hydrogel microspheres is dissolved or decomposed by heating or adding corresponding solvents to the fluid, releasing the Micro LED chips wrapped in 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. By utilizing microfluidics technology to wrap hydrogel around Micro LEDs and utilizing a dielectrophoresis trap array on a substrate to capture Micro LED hydrogel microspheres, a layer of hydrogel is wrapped around the surface of the Micro LED. The electric field effect of the dielectrophoresis trap array is then used to capture the hydrogel particles at specific positions on the target substrate. By adjusting the electric field parameters, precise positioning and control of the Micro LED hydrogel microspheres are achieved, completing high-precision transfer of the Micro LED chip. This improves the transfer efficiency and positioning accuracy of the Micro LED, simplifies the Micro LED transfer process, reduces production costs, 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, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection 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 lift-off, the Micro LED chip is mixed into a liquid. The co-flow focusing method in microfluidics is used to make the Micro LED chip into independent Micro LED chip hydrogel microspheres wrapped in hydrogel. S2: Suspending the Micro LED chip hydrogel microspheres made from the Micro LED chip in a commonly used liquid; S3: Use corresponding PL testing 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: Using fluid force to evenly distribute the selected Micro LED chip hydrogel microspheres that meet the requirements onto the target substrate, and then using 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 substrate surface, the dielectrophoresis trap current switch is turned on. The dielectrophoresis traps prepared on the target substrate gradually capture the Micro LED chip hydrogel microspheres, forming a large-scale ordered array. S6: After assembly is completed, the excess Micro LED chip hydrogel microspheres are removed by a clean fluid, and the ordered array of Micro LED chip hydrogel microspheres is dissolved or decomposed to release the Micro LED chips wrapped in the Micro LED chip hydrogel microspheres, 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 according to claim 3, characterized in that: In step S4, the ring 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 according to claim 4, characterized in that: The dielectrophoretic trap is fabricated using photolithography and consists of two metal ring electrodes with an interlayer dielectric insulator between them.

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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