Colloidal photonic crystal array chip, construction method, and application

Abstract

The present invention relates to the field of micro-nano manufacturing, photonic functional materials, and optoelectronic system integration technology, and discloses a colloidal photonic crystal array chip, a construction method, and an application. The construction method of the colloidal photonic crystal array chip comprises the following steps: preparing a monodisperse colloidal photonic crystal dispersion with a particle size of 200nm-400nm; making a chip substrate with a regular array cavity structure; injecting the colloidal photonic crystal dispersion into each array cavity unit of the regular array cavity structure of the chip substrate; controlling the temperature and humidity environment, evaporating and drying, so that the colloidal particles self-assemble into a film; and providing a flexible film or glass layer on the surface of the chip substrate for encapsulation to form a photonic crystal array chip with a stable structure. The chip has the advantages of high assembly precision, strong color uniformity, and good structural stability, and can be widely used in scenarios such as smart sensing, optical labels, color displays, and biometrics.

Description

Technical Field

[0001] The present invention relates to the fields of micro-nano manufacturing, photonic functional materials, and optoelectronic system integration, and in particular, to a method for constructing a colloidal photonic crystal array chip based on colloidal photonic crystals. Furthermore, the present invention also relates to a colloidal photonic crystal array chip constructed using the aforementioned method for constructing a colloidal photonic crystal array chip, and its applications. Background Art

[0002] Colloidal photonic crystals (CPCs) are optically functional materials composed of periodically arranged colloidal microspheres. Their unique photonic bandgap properties and structural color effects hold significant potential for applications in display technology, optical sensing, laser design, and information encryption. The presence of a PBG enables the material to selectively reflect specific wavelengths of light, producing vibrant structural colors without the need for chemical dyes, offering environmental and fade-resistant advantages.

[0003] However, existing technologies still have significant limitations, which restrict the practical application of colloidal photonic crystal materials. Specifically, they are manifested in the following technical difficulties:

[0004] 1. Insufficient array chip-level construction: The current process makes it difficult to achieve precise positioning and distribution control of droplets in high-resolution arrays, which can easily cause edge effects or non-uniform deposition, affecting the periodic arrangement of photonic crystals and resulting in inconsistent optical performance between units.

[0005] 2. Film quality defects: Colloidal droplets are prone to cracking, coffee ring effects, or aperiodic aggregation during localized film formation, disrupting the long-range ordered structure and leading to a decrease in structural color saturation or wavelength shift. Existing methods such as annealing and solvent manipulation are not universally applicable to address this issue.

[0006] 3. Lack of modular integration technology: There is a lack of packaging solutions that are compatible with functional devices. The existing packaging process is difficult to balance long-term stability and optical performance, which limits its application in complex scenarios. Summary of the Invention

[0007] The present invention provides a colloidal photonic crystal array chip and its construction method and application, which combines the processes of controllable droplet positioning, local film formation, self-organized assembly and device-level packaging. It has the advantages of high assembly precision, strong color uniformity, and good structural stability. It can be widely used in scenarios such as smart sensing, optical labels, color display and biometrics, so as to solve the technical problems of the preparation of existing colloidal photonic crystal materials, insufficient array chip-level construction, film quality defects, and lack of modular integration technology.

[0008] According to one aspect of the present invention, a method for constructing a colloidal photonic crystal array chip is provided, comprising the following steps: S100, preparing a monodisperse colloidal photonic crystal dispersion having a particle size of 200nm-400nm; S200, making a chip substrate with a regular array cavity structure; S300, injecting the colloidal photonic crystal dispersion into each array cavity unit of the regular array cavity structure of the chip substrate; S400, controlling the temperature and humidity environment, evaporating and drying, and allowing the colloidal particles to self-assemble into a film; S500, providing a flexible film or glass layer on the surface of the chip substrate for encapsulation to form a photonic crystal array chip with a stable structure.

[0009] Furthermore, in step S100, the particles in the colloidal photonic crystal dispersion are selected from polystyrene or SiO2 nanoparticles.

[0010] Furthermore, colloidal particles of polystyrene or SiO2 nanoparticles with a particle size of 200nm-400nm and PDI <0.1 were prepared using microfluidic emulsion polymerization technology and dispersed in pure water or ethanol-water mixed solvent to form a stable colloidal dispersion.

[0011] Furthermore, in step S200, the material of the chip substrate is selected from PDMS, glass, silicon or optical polymer; or the chip substrate is an optical polymer substrate.

[0012] Furthermore, the diameter of the array cavity is 100 μm–300 μm, and the depth is 10 μm–100 μm.

[0013] Furthermore, step S300 specifically includes: injecting a small amount of photonic crystal dispersion into each array cavity unit by air pressure micro-spraying, capillary injection or confined drop coating technology.

[0014] Furthermore, in step S400 , the self-assembly film forming process is performed at a temperature of 40° C.–60° C. and a relative humidity of 30%–50%.

[0015] Furthermore, in step S500, the packaging method is UV curing resin, low temperature hot melt adhesive or glass bonding.

[0016] According to another aspect of the present invention, a colloidal photonic crystal array chip is provided, which is constructed using the above-mentioned method for constructing a colloidal photonic crystal array chip.

[0017] According to another aspect of the present invention, a modular integrated application of a colloidal photonic crystal array chip is provided, wherein the colloidal photonic crystal array chip is used for modular integration to form an optical response module, a structural color output module or a coding recognition module.

[0018] The present invention has the following beneficial effects:

[0019] In the method for constructing a colloidal photonic crystal array chip, the particle size of the colloidal photonic crystal dispersion (200nm-400nm) determines the position of the photonic band gap, and the monodispersity ensures the purity of the structural color. By fabricating a chip substrate with a regular array cavity structure, a physically confined space is provided for the positioning of the colloidal photonic crystal dispersion. The array cavity structure, with its microcavity size matching the colloidal particles, promotes close packing and avoids the formation of polycrystalline domains. When the monodisperse colloidal photonic crystal dispersion is injected into each array cavity unit, the cavity structure effectively constrains the diffusion range of the droplets, avoiding cross-contamination between adjacent units, thereby ensuring the spatial arrangement accuracy and optical performance consistency of the array units. This method directly solves the problem of traditional methods' difficulty in achieving precise droplet positioning in high-resolution arrays from a physical structural perspective. By controlling the temperature and humidity environment, colloidal particles are self-assembled into films. Temperature and humidity control and slow evaporation induce colloidal particles to self-assemble into face-centered cubic (FCC) or hexagonal close-packed (HCP) structures in the microcavity, optimizing optical performance. Under the confining effect of the regular array cavity, the colloidal dispersion is constrained by the cavity wall during the evaporation and drying process, and the evaporation dynamics tend to be uniform, avoiding the coffee ring effect common in traditional open droplets. At the same time, the precise control of the temperature and humidity environment enables colloidal particles of 200nm-400nm to slowly and orderly self-assemble to form a periodic arrangement structure, significantly reducing defects such as cracking and non-periodic aggregation, and directly improving the uniformity and optical quality of the structural color. During the packaging process, a flexible film or glass layer is provided on the surface of the chip substrate for packaging, providing mechanical protection and environmental isolation for the photonic crystal array; the flexible film can adapt to the integration requirements of curved or flexible devices, while the glass layer can provide rigid protection. Both can effectively block the damage of external humidity, oxygen and mechanical stress to the photonic crystal structure, thereby ensuring the long-term stability of the chip in complex application scenarios; it directly solves the problem of the lack of reliable modular packaging in the existing technology, making the photonic crystal array compatible and integrated with various functional devices. The colloidal photonic crystal array chip construction method provided by the present invention realizes high-precision array construction, stable film formation and reliable packaging through the synergistic effect of specific process steps; the regular array cavity structure directly limits the positioning accuracy of the droplets, the self-assembly process under temperature and humidity control directly determines the orderliness of the film formation, and the selection of the encapsulation layer is directly related to the environmental stability; the synergistic effect of each step realizes the high precision, high stability and application compatibility of the colloidal photonic crystal array chip; it can be widely used in scenarios such as smart sensing, optical labels, color display and biometrics.

[0020] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention is further described in detail below. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0022] Figure 1 2 is a schematic structural diagram of a passive protective film on a chip surface according to a preferred embodiment of the present invention;

[0023] Figure 2 It is a schematic cross-sectional structural diagram of a module-level secure package based on a flexible film according to a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0024] The following examples of the present invention are described in detail, but the present invention can be implemented in a variety of different ways as defined and covered below. Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0025] The method for constructing a colloidal photonic crystal array chip of this embodiment includes the following steps: S100, preparing a monodisperse colloidal photonic crystal dispersion with a particle size of 200nm-400nm; S200, making a chip substrate with a regular array cavity structure; S300, injecting the colloidal photonic crystal dispersion into each array cavity unit of the regular array cavity structure of the chip substrate; S400, controlling the temperature and humidity environment, evaporating and drying, so that the colloidal particles self-assemble into a film; S500, providing a flexible film or glass layer on the surface of the chip substrate for encapsulation to form a structurally stable photonic crystal array chip. In the method for constructing a colloidal photonic crystal array chip of the present invention, the particle size of 200nm-400nm of the colloidal photonic crystal dispersion determines the position of the photonic band gap, and the monodispersity ensures the purity of the structural color. By making a chip substrate with a regular array cavity structure, a physically confined space is provided for the positioning of the colloidal photonic crystal dispersion; the array cavity structure and the microcavity size match the colloidal particles, promoting close stacking and avoiding the formation of polycrystalline domains; when the monodisperse colloidal photonic crystal dispersion is injected into each array cavity unit, the cavity structure can effectively constrain the diffusion range of the droplets, avoiding cross-contamination between adjacent units, thereby ensuring the spatial arrangement accuracy and optical performance consistency of the array units; directly solving the problem of traditional methods being difficult to achieve precise positioning of droplets in high-resolution arrays from a physical structure perspective. By controlling the temperature and humidity environment, colloidal particles are self-assembled into films. Temperature and humidity control and slow evaporation induce colloidal particles to self-assemble into face-centered cubic (FCC) or hexagonal close-packed (HCP) structures in the microcavity, optimizing optical performance. Under the confining effect of the regular array cavity, the colloidal dispersion is constrained by the cavity wall during the evaporation and drying process, and the evaporation dynamics tend to be uniform, avoiding the coffee ring effect common in traditional open droplets. At the same time, the precise control of the temperature and humidity environment enables colloidal particles of 200nm-400nm to slowly and orderly self-assemble to form a periodic arrangement structure, significantly reducing defects such as cracking and non-periodic aggregation, and directly improving the uniformity and optical quality of the structural color. During the packaging process, a flexible film or glass layer is set on the surface of the chip substrate for packaging, providing mechanical protection and environmental isolation for the photonic crystal array; the flexible film can adapt to the integration requirements of curved or flexible devices, while the glass layer can provide rigid protection. Both can effectively block the damage to the photonic crystal structure caused by external humidity, oxygen and mechanical stress, thereby ensuring the long-term stability of the chip in complex application scenarios; it directly solves the problem of the lack of reliable modular packaging in existing technologies, making the photonic crystal array compatible and integrated with various functional devices.The colloidal photonic crystal array chip construction method provided by the present invention realizes high-precision array construction, stable film formation and reliable packaging through the synergistic effect of specific process steps; the regular array cavity structure directly limits the positioning accuracy of the droplets, the self-assembly process under temperature and humidity control directly determines the orderliness of the film formation, and the selection of the encapsulation layer is directly related to the environmental stability; the synergistic effect of each step realizes the high precision, high stability and application compatibility of the colloidal photonic crystal array chip; it can be widely used in scenarios such as smart sensing, optical labels, color display and biometrics.

[0026] In this embodiment, in step S100, polystyrene (PS) or silicon dioxide (SiO2) nanoparticles are selected as the core material of the colloidal photonic crystal dispersion; the particle size range of PS particles and SiO2 nanoparticles (200nm-400nm) directly corresponds to the structural color reflection in the visible light band (about 400nm-700nm); by adjusting the particle size, selective reflection of the target wavelength can be achieved, meeting the requirements of specific colors for applications such as display and sensing, and realizing precise control of the photonic band gap; the refractive index of PS and the refractive index of SiO2 both form a significant refractive index difference with the air medium or the water medium, enhancing the Bragg scattering effect, thereby improving the saturation and brightness of the structural color and achieving high refractive index contrast. Monodisperse (particle size deviation <5%) colloidal solutions of PS or SiO2 particles can be prepared via emulsion polymerization or the Stöber method. Monodisperse particles maintain orderly arrangement during evaporation-induced self-assembly, more readily forming long-range ordered structures of face-centered cubic (FCC) or hexagonal close-packed (HCP), thus avoiding the formation of polycrystalline domains or defects. The hydrophobic surface of PS particles can be modified with octadecyltrichlorosilane (OTS) and other agents to regulate wettability with the substrate and suppress the coffee-ring effect. The hydrophilic surface of SiO2 particles is suitable for aqueous dispersion and can be functionalized with silane coupling agents, facilitating subsequent biosensing applications (such as antibody grafting). PS and SiO2 are resistant to corrosion by water, oxygen, and weak acids and bases at room temperature, ensuring that colloidal photonic crystal dispersions do not aggregate or degrade during storage and processing. The flexibility of PS particles is well-suited for flexible device packaging (such as PDMS substrates) and resists shattering under bending conditions. The high hardness of SiO2 particles is suitable for rigid packaging (such as glass layers), providing mechanical protection. PS or SiO2 particles spontaneously and orderly stack during confined evaporation, reducing cracking and aperiodic aggregation. For array construction, the surface chemical properties of the particles (such as hydrophobic or hydrophilic modification) assist droplets in precisely filling microcavities. For packaging requirements, the intrinsic stability of the materials (flexible PS and hard SiO2) directly matches the performance requirements of the encapsulation layer. The selection of PS or SiO2 nanoparticles allows for precise control of structural color through the correlation between particle size and optical properties. Monodispersity and surface chemistry ensure high-quality self-assembly. The intrinsic properties of the materials meet the requirements of different packaging scenarios. This choice directly matches the technical goals of array construction, film optimization, and packaging stability.

[0027] In this example, colloidal particles of polystyrene or SiO2 nanoparticles with a particle size of 200nm–400nm and a PDI of less than 0.1 were prepared using microfluidic emulsion polymerization technology and dispersed in pure water or an ethanol-water mixture to form a stable colloidal dispersion. Highly monodisperse (PDI <0.1) polystyrene (PS) or silica (SiO2) nanoparticles were prepared using microfluidic emulsion polymerization technology and dispersed in pure water or an ethanol-water mixture to form a stable colloidal dispersion. Microfluidic technology can prepare PS particles or SiO2 nanoparticles with uniform particle size (PDI < 0.1) by precisely controlling the two-phase flow rate, interfacial shear force and reaction time. The particle size is 200nm-400nm. Monodispersity directly determines the quality of the long-range ordered structure formed by colloidal particles during the self-assembly process, avoiding the generation of polycrystalline domains or defects, thereby improving the purity and consistency of structural color. The particle size range of 200nm-400nm precisely matches the visible light band, and the monodispersity (PDI < 0.1) ensures the narrowing of the photonic band gap, significantly reducing the half-width of the reflection peak, and enhancing color saturation. Pure water systems are suitable for hydrophilic SiO2 particles. Highly polar solvents promote electrostatic stabilization of the particles, preventing agglomeration during storage. Ethanol-water mixed solvents: The addition of ethanol can adjust the hydrophobic surface wettability of PS particles, improving droplet spreading uniformity during microcavity filling and reducing the coffee ring effect caused by contact line pinning. The addition of ethanol accelerates evaporation (the slow evaporation of pure water can easily induce particle migration), allowing for faster and more orderly accumulation of particles within the confines of the microcavity. Microfluidic emulsion polymerization enables the continuous production of highly monodisperse particles, overcoming the batch variability issues of traditional emulsion polymerization and providing a stable source of raw materials for chip-scale array construction. Pure water systems are compatible with hydrophilic encapsulation materials (such as SiO2 glass layers). Ethanol-water systems are compatible with hydrophobic flexible films (such as PDMS), leaving no residue after solvent evaporation, thus preventing porosity or debonding at the encapsulation interface. To address film formation defects, monodisperse particles (PDI <0.1) and solvent volatilization control synergistically suppress coffee rings and cracking. For array construction, stable dispersions ensure uniform droplet concentration during microcavity filling, avoiding performance fluctuations between units. To meet packaging requirements, solvent selection directly matches the subsequent packaging process (e.g., ethanol-water systems adapt to PDMS curing temperatures). Microfluidic emulsion polymerization technology combined with pure water or ethanol-water solvent systems can optimize optical performance, with monodisperse particles (PDI <0.1) ensuring narrow band gaps and highly saturated structural colors. Solvent selection directly addresses droplet filling and evaporation control issues, achieving improved process stability. As the foundation for large-scale production, microfluidics provides uniform raw materials for chip-scale applications.

[0028] In this embodiment, in step S200, the chip substrate material is selected from PDMS, glass, silicon, or an optical polymer; alternatively, the chip substrate is an optical polymer substrate. PDMS and optical polymers (such as PMMA) have high light transmittance, ensuring distortion-free display of photonic crystal structural colors. Glass and silicon wafers provide ultra-smooth surfaces, reducing light scattering losses. Silicon substrates are particularly suitable for multifunctional devices requiring subsequent microelectronic integration. PDMS can achieve microcavity arrays with 1μm-100μm precision through soft lithography. Glass / silicon supports photolithography and etching processes, making it suitable for fabricating high-precision nanoscale cavities. Optical polymers can be hot-stamped or injection-molded, making them suitable for large-scale production. The hydrophobic surface of PDMS can regulate the wetting behavior of colloidal droplets. The hydrophilic surface of glass or SiO2 promotes uniform spreading of aqueous dispersions. Surface energy matching can optimize the self-assembly orientation of colloidal particles (e.g., FCC or HCP). PDMS is suitable for flexible wearable devices. Glass or silicon provides rigid support and strong deformation resistance. Optical polymers (such as PMMA) balance flexibility and dimensional stability. PDMS requires careful thermal matching with the encapsulation layer; glass and SiO2 particles exhibit similar thermal expansion behavior; silicon is suitable for high-temperature process integration. The PDMS surface can be hydrophilized through oxygen plasma treatment; glass or Si surfaces can be easily silanized; and optical polymers can be treated with UV-ozone to improve wettability.

[0029] In this embodiment, the array cavity diameter ranges from 100μm to 300μm, and the depth ranges from 10μm to 100μm. The cavity volume of the array cavity is matched to the surface tension of the CPC dispersion, ensuring that each cavity forms an independent droplet. The lower diameter limit of 100μm prevents filling difficulties caused by capillary effects, while the upper diameter limit of 300μm prevents gravity from destabilizing the droplet, enabling precise control of droplet volume. The 10μm to 100μm depth design creates a specific aspect ratio (0.03–1). Shallow cavities (10μm–30μm) accelerate solvent evaporation, facilitating rapid self-assembly. Deep cavities (50μm–100μm) slow evaporation and promote more ordered particle arrangement. The diameter-to-depth ratio (3:1 to 30:1) optimizes Marangoni convection and suppresses the coffee ring effect, enabling kinetic control of evaporation. The cavity diameter limits the size of the self-assembly domain of colloidal particles, enabling adaptive monolayer arrangement and controlled growth of polycrystalline domains based on particle size distribution. The depth dimension constrains the number of particle stacking layers, thereby balancing optical intensity and response speed, thereby achieving control of the photonic crystal structure. A diameter >100μm ensures that a single cavity forms a complete interference pattern in the visible light range, while a depth >10μm provides sufficient optical path to enhance the intensity of Bragg reflection. A diameter of 300μm approaches the resolution limit of the human eye, achieving visual uniformity. The array cavity diameter of 100μm–300μm is compatible with the precision of conventional photolithography / micromachining processes, while a depth of 10μm–100μm matches the thickness of standard SU-8 photoresist. This size range allows for processing using low-cost contact exposure equipment, ensuring process compatibility. The 100μm cavity is suitable for high-density integration; the 300μm cavity is convenient for subsequent functional modification (such as fixation of biological probes); the 10μm shallow cavity is suitable for ultra-fast response sensors; the 100μm deep cavity enhances mechanical strength; this size design solves the arraying problem through physical confinement and clear boundaries to prevent crosstalk between units, solves the film quality problem by regulating the evaporation self-assembly process through geometric parameters, and solves the integration problem by matching the subsequent packaging process with standardized dimensions.

[0030] In this embodiment, step S300 specifically involves injecting a small amount of photonic crystal dispersion into each array cavity unit via pneumatic micro-spraying, capillary injection, or confined droplet coating. Pneumatic micro-spraying uses a piezoelectric or pneumatic nozzle to generate tiny droplets, filling the cavity in a non-contact manner to avoid cross-contamination. The inkjet accuracy (±2μm) ensures that the droplets precisely land within a cavity with a diameter of 100μm–300μm, addressing the positioning deviation problem of traditional droplet coating. Capillary injection utilizes the capillary force of a hydrophilic cavity (such as a glass or SiO2 substrate) to spontaneously draw liquid, or the confinement effect of a hydrophobic cavity (such as PDMS) to achieve self-stopping filling. The liquid column height (10μm–100μm) is directly controlled by the cavity depth, with a volumetric error of <5%. Confined droplet coating uses microneedle contact dispensing to achieve selective wetting on a hydrophobic-hydrophilic patterned surface. The droplet is automatically confined to the center of the cavity due to surface energy constraints. High-precision droplet positioning and volume control can be achieved, overcoming the challenges of inaccurate droplet positioning and crosstalk between cells during array fabrication, thereby meeting the process requirements of high-resolution arrays. The instantaneous impact of air pressure microspraying breaks up particle migration, while the continuous wetting and evaporation rate equilibrium of capillary injection reduce edge deposition, promote uniform distribution of colloidal particles (200nm–400nm) within the cavity, and suppress the coffee ring effect. Confined drop coating achieves uniform droplet spreading thickness through surface energy matching (e.g., hydrophilic cavity and water-based dispersion). Combined with subsequent temperature and humidity control, it enables slow, orderly self-assembly, avoiding cracking and aperiodic aggregation. This reduces film formation defects (cracks and coffee rings) at the source of filling, improving the color quality of photonic crystal structures. Air pressure microspraying is suitable for high-speed array filling on rigid substrates (glass or silicon); capillary injection matches the deformation tolerance of flexible PDMS; confined drop coating is compatible with surface modification of optical polymers (such as PMMA) and is adaptable to a variety of substrate materials. Parallel operation of multiple pneumatic micro-spray nozzles or batch impregnation using capillary injection significantly improves chip-scale array fabrication efficiency and supports high-throughput production. This provides a scalable process foundation for modular system integration, meeting the production capacity requirements of practical application scenarios.

[0031] In this embodiment, in step S400, the self-assembly film formation process is performed at a temperature of 40°C–60°C and a relative humidity of 30%–50%. The temperature is controlled between 40°C and 60°C during the self-assembly film formation process to maintain the solvent (water or ethanol) evaporation rate within the optimized range. At 60°C, the water evaporation rate increases approximately five times compared to room temperature, while avoiding boiling disturbances. The ethanol mixed solvent achieves azeotropic equilibrium at 50°C. The humidity is controlled between 30% and 50% during the self-assembly film formation process. A low humidity of 30% accelerates evaporation and is suitable for complete drying of deep cavities (50μm-100μm). A humidity of 50% helps inhibit excessive surface drying and prevents cracking in shallow cavities (10μm-30μm). A humidity of 40% is more conducive to achieving a uniform advance of the evaporation front. Colloidal particle self-assembly is optimized. Within the temperature range of 40°C–60°C, higher temperatures increase the Brownian motion rate of the colloidal particles (200nm-400nm), promoting the formation of FCC structures. At thermodynamic equilibrium, the interparticle van der Waals force and electrostatic repulsion achieve an optimal balance. At a relative humidity of 30%–50%, capillary forces stabilize the interparticle spacing, maintaining it at approximately 1x the particle diameter, promoting orderly stacking. The humid environment maintains liquid film continuity, reducing cracking caused by drying stress, while the small temperature gradient prevents non-uniform deposition caused by Malaga convection. The evaporation rate is matched to the particle diffusion rate. A constant temperature ensures consistent evaporation behavior across cells, while humidity control minimizes differences in drying time for cavities with different aspect ratios. Coordinated temperature-humidity control achieves matching evaporation rate with particle settling rate, minimizing the gas-liquid interfacial energy gradient and increasing particle packing density. The low-temperature process (<60°C) is compatible with polymer substrates such as PDMS, and progressive drying prevents microcracks at the encapsulation interface.

[0032] In this embodiment, in step S500, the encapsulation method is UV-curable resin, low-temperature hot-melt adhesive, or glass bonding. UV-curable resin encapsulation uses ultraviolet light to trigger resin cross-linking and curing, forming a transparent protective layer on the surface of the photonic crystal. The curing process is completed at room temperature to prevent high temperatures from damaging the ordered arrangement of the colloidal particles. The resin's refractive index matches that of PS or SiO2, controlling interface reflection loss below 5% and maintaining structural color saturation. The three-dimensional cross-linked network mechanically fixes the position of the colloidal particles to prevent lattice expansion or cracking caused by humidity changes. The cross-linked and cured resin layer isolates water and oxygen from penetrating, addressing environmental stability issues. The curing shrinkage rate is less than 3%, preventing packaging stress from damaging the microcavity array structure. Low-temperature hot-melt adhesive encapsulation uses thermoplastic polymers (such as EVA) with a melting temperature of 80°C-120°C. The low-temperature hot-pressing process does not trigger the glass transition of the colloidal particles, thereby maintaining the optical properties of the photonic crystal. The molten hot-melt adhesive can completely fill the microcavity gap, eliminating light scattering caused by air gaps. The elastic modulus matches that of flexible substrates (such as PDMS), making it resistant to bending deformation. After cooling and solidifying, the hot-melt adhesive forms a physical barrier to prevent mechanical friction from damaging the microcavity units. The material's inherent hydrophobicity resists erosion in humid environments. Glass-bonded encapsulation achieves rigid encapsulation through anodic bonding or optical adhesive bonding. The extremely high light transmittance and surface flatness of the glass maximize the preservation of structural color characteristics. The airtight encapsulation provides long-term environmental stability. The thermal expansion coefficient matches that of the silicon or glass substrate to avoid interface delamination caused by thermal cycling. The rigid support of the hard glass inhibits crack propagation caused by stress within the film. Anodic bonding is directly compatible with semiconductor processes, enabling optoelectronic integration.

[0033] The colloidal photonic crystal array chip of this embodiment is constructed using the above-mentioned method for constructing a colloidal photonic crystal array chip.

[0034] The modular integration application of the colloidal photonic crystal array chip of this embodiment uses the colloidal photonic crystal array chip for modular integration to form an optical response module, a structural color output module or a coding recognition module.

[0035] During implementation, a method for constructing a colloidal photonic crystal array chip based on colloidal photonic crystals and its integrated application in an optical module is provided. The method first prepares a colloidal photonic crystal dispersion with a monodisperse particle size, and guides the droplets into a pre-designed microstructure chip array unit by drop coating, confined self-assembly, etc. The droplets spontaneously form a film in the local area to form a periodic structural color film; then, the film is encapsulated with a flexible packaging material to construct a photonic crystal array module that can stably output reflective structural color. This technical solution combines processes such as controllable droplet positioning, local film formation, self-organized assembly, and device-level packaging. It has the advantages of high assembly accuracy, strong color uniformity, and good structural stability. It is widely applicable to scenarios such as smart sensing, optical labels, color displays, and biometrics.

[0036] The method for constructing a photonic crystal array chip based on colloidal photonic crystals comprises the following steps:

[0037] (1) Preparation of photonic crystal dispersion: Polystyrene or SiO2 colloidal particles with a particle size of 200 nm–350 nm and a PDI < 0.1 are prepared using microfluidic emulsion polymerization technology and dispersed in pure water or ethanol-water mixed solvent to form a stable colloidal dispersion;

[0038] (2) Array chip design and construction: Design and prepare a chip with a regular array microcavity structure (chip materials such as PDMS, glass, silicon substrate materials; or optical polymer materials), with each array unit having a diameter of 100 μm–300 μm and a depth of 10 μm–100 μm;

[0039] (3) Droplet deposition and self-assembly: A small amount of photonic crystal dispersion is precisely injected into the microcavity unit through air pressure micro-injection, capillary injection or confined drop coating technology, and the environment is controlled (temperature 40℃–60℃, humidity 30%–50%) for evaporation and drying, so that the colloidal particles self-assemble in the cavity to form a photonic crystal structure;

[0040] (4) Array fixation and packaging: Cover the array with a transparent flexible film or glass cover for packaging. The packaging method can be pressing, PDMS lamination, UV curing glue or low-temperature hot melt bonding;

[0041] (5) Module integration and output: Integrate the chip with module circuits, flexible connectors, micro light sources or sensor elements to form an optical response module, structural color output module or coding recognition module.

[0042] Specifically, a colloidal photonic crystal array chip is integrated with a micro light source, a module circuit, and a flexible connector to form a structural color output module.

[0043] Specifically, the colloidal photonic crystal array chip is integrated with the sensor element, the module circuit, and the flexible connector to form a coding recognition module.

[0044] Specifically, by integrating colloidal photonic crystal array chips, module circuits and flexible connectors; and selectively combining: micro light sources to achieve dynamic structural color output; sensing elements to convert detection signals into optical codes.

[0045] Specifically, when the colloidal photonic crystal array chip is integrated with a micro-light source, the structural color of the photonic crystal is excited by the light source to form an optical response / structural color output module.

[0046] Specifically, when the colloidal photonic crystal array chip integrates the sensing element, the photonic crystal structure is changed by the sensing signal, and a recognizable optical code is output.

[0047] Example 1:

[0048] (1) Preparation of colloidal particle dispersion: Polystyrene (PS) colloidal particles with an average particle size of 240 nm and a particle size distribution index (PDI) of 0.07 were prepared by microfluidic emulsion polymerization and dispersed in pure water to form a stable colloidal dispersion with a mass concentration of 5 wt%.

[0049] (2) Preparation of chip array structure: Laser micromachining technology is used to etch the array structure on the surface of PDMS elastomer, with a pore diameter of 200 μm, a depth of 50 μm, and an array period of 300 μm × 300 μm, forming a regularly arranged circular cavity array.

[0050] (3) Droplet injection and confined assembly: A precision micro-syringe was used to inject 0.4 μL of colloidal dispersion into each array unit, and the cells were placed in a constant temperature and humidity chamber and dried naturally for 12 hours at 50°C and 40% relative humidity. During the drying process, the colloidal particles spontaneously assembled in the confined space to form a photonic crystal structure.

[0051] (4) Package fixation: Apply UV curable transparent resin (such as NOA63) on the surface of the dried array chip, cover it with a layer of glass, and cure the package under ultraviolet light.

[0052] (5) Performance testing: The array chip was measured using a reflectance spectrometer. The reflection peak was concentrated at 560nm–580nm, indicating that the crystals were arranged regularly and had obvious structural colors. The SEM image showed that the crystal structure in the array was a typical hexagonal close-packed arrangement.

[0053] Example 2:

[0054] (1) Preparation of array chip: The preparation method is the same as that in Example 1. Polystyrene particles are used to make a photonic crystal array chip. The array size is 8×8, with a total of 64 color-emitting units.

[0055] (2) Flexible circuit module design: A flexible printed circuit board (FPC) is used as a carrier platform, embedded with a micro-LED array to provide controllable illumination light sources of different wavelengths (450nm, 520nm, 630nm); the circuit board connects the communication module and the temperature and humidity sensor.

[0056] (3) Chip packaging and integration: The dried photonic crystal array chip is fixed to the module and sealed with hot melt adhesive. The LED array is located under the chip to provide backlight excitation, and the sensor collects ambient environmental parameters.

[0057] (4) Functional verification: When the module is placed in different humidity environments (30%, 60%, and 90%), the structural color undergoes a reversible shift, and the reflection peak moves from 540nm to 590nm. At the same time, by controlling the LED switch, color recognition and environmental data can be read synchronously.

[0058] (5) Application scenarios: The module can be used in scenarios such as environmental visualization sensor tags, wearable structural color identifiers, and smart product identity anti-counterfeiting tags, showing good responsiveness and stability.

[0059] In addition, an integrated security packaging application of a colloidal photonic crystal array chip based on colloidal photonic crystals is provided: a module-level security packaging technology based on a flexible composite film. Specifically, the following steps are included:

[0060] 1. Preparation of colloidal crystal thin films: Microfluidics technology is used to precisely control the arrangement of colloidal particles to form colloidal crystal thin films with stable optical properties. The preparation process of colloidal crystal thin films is as follows:

[0061] Colloidal particle preparation: Use high-quality nanoparticles (such as polystyrene or silica) to prepare colloidal particle solutions to ensure particle uniformity and stability.

[0062] Solution injection into microfluidic chip: The colloidal particle solution is injected into the microchannels of the microfluidic chip. The microfluidic chip is designed with multiple tiny channels for precise control of fluid flow.

[0063] Microfluidics regulates particle arrangement: By adjusting the flow rate and fluid dynamics of the microfluidic chip, the arrangement of particles is precisely controlled, causing them to self-assemble into colloidal crystal films with a periodic structure. Microfluidics ensures precise particle arrangement at the microscale.

[0064] Film curing and stability testing: After the film is formed, it is cured to ensure its structural stability and the optical performance stability test is performed.

[0065] The combination of microfluidics and colloidal crystal thin films enables precise control of the flow of colloidal particles within microchannels, ensuring the consistency of the film's optical properties and structure, thereby ensuring the stability of each film under different environments. Compared with traditional thin film preparation methods, the introduction of microfluidics allows for more precise particle arrangement and maintains consistency in the film's optical properties during large-scale production. Through this precise control, the present invention can generate highly random and unique optical "fingerprints," significantly improving the security of PUF systems.

[0066] 2. Optical PUF system design: The prepared colloidal crystal film is applied to the PUF system, and its unique optical "fingerprint" generates a unique authentication code for encryption and anti-counterfeiting purposes. The optical PUF system design is as follows:

[0067] Microfluidic thin film optical sensor (colloidal crystal film): Colloidal crystal film is used as an optical sensor. When a light source (laser or light-emitting diode) is irradiated onto the surface of the film, the optical "fingerprint" of the film exhibits unique optical properties based on its microstructure.

[0068] Light source and optical sensor: A laser or light-emitting diode is used as the light source to generate an optical signal based on the reflection or transmission characteristics of the film. An optical sensor (such as a photodetector) receives the reflected or transmitted light and identifies the optical "fingerprint" of the film by measuring the optical signal at a specific wavelength.

[0069] Unique optical "fingerprint" generation and encryption: The optical characteristics read by the optical sensor are converted into a unique "fingerprint" information. This "fingerprint" is used to generate encrypted information, which can serve as the key for authentication of encryption modules or anti-counterfeiting labels.

[0070] Security authentication and encryption applications: The resulting optical "fingerprint" is used in security authentication systems or encryption modules to provide unique identity authentication codes for different devices, enhancing device security.

[0071] Module-level security packaging technology based on flexible composite films, integrating advanced composite film materials and highly reliable PUF extraction technology, and the construction technology of colloidal photonic crystal array chips based on colloidal photonic crystals with independent and controllable processes, constructs flexible composite films with random texture characteristics, and thus forms a module-level security packaging solution, such as Figure 1 shown.

[0072] In order to ensure the protection effect of module-level security packaging, the wrapping method of the flexible film and the structure of the security module must be systematically designed. The structure of the flexible film and the security module constructed by the construction method of the colloidal photonic crystal array chip based on colloidal photonic crystals ensures that the attacker will inevitably affect the film properties after disassembling the flexible film, and thus cannot recover the PUF key based on the flexible composite film. The cross-sectional diagram of the module-level security packaging based on the flexible composite film is shown as follows: Figure 2 As shown, the flexible film wraps the module and measurement circuit together, and the internal connections are made through board-level interconnect signals. If an attacker disassembles the flexible film, it will cause the film to deform, which in turn causes changes in the film properties and causes key recovery failure.

[0073] Matters not covered by the present invention are known technologies.

[0074] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0075] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

[0076] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for constructing a colloidal photonic crystal array chip, characterized in that: The following steps are involved: S100, preparing a monodisperse colloidal photonic crystal dispersion with a particle size of 200 nm–400 nm and a PDI < 0.1; S200, manufacturing a chip substrate with a regular array cavity structure, wherein the diameter of the array cavity structure is 100 μm-300 μm, the depth is 10 μm-100 μm, and the aspect ratio is 0.03-1; S300, injecting colloidal photonic crystal dispersion into each array cavity unit of the regular array cavity structure of the chip substrate; S400, evaporating and drying at a temperature of 40° C. to 60° C. and a relative humidity of 30% to 50%, so that the colloidal particles are self-assembled in each array cavity unit into a photonic crystal film having a face-centered cubic or hexagonal close-packed structure; S500, providing a flexible film or glass layer on the surface of the chip substrate for packaging, wherein the packaging method is UV curable resin, low temperature hot melt adhesive or glass bonding to form a photonic crystal array chip with a stable structure.

2. The method for constructing a colloidal photonic crystal array chip according to claim 1, characterized in that: In step S100, the particles in the colloidal photonic crystal dispersion are polystyrene or SiO2 nanoparticles.

3. The method for constructing a colloidal photonic crystal array chip according to claim 2, characterized in that: Microfluidic emulsion polymerization technology is used to prepare colloidal particles of polystyrene or SiO2 nanoparticles with a particle size of 200nm-400nm and PDI <0.1, and they are dispersed in pure water or ethanol-water mixed solvent to form a stable colloidal dispersion.

4. The method for constructing a colloidal photonic crystal array chip according to claim 1, wherein: In step S200, the chip substrate is made of PDMS, glass or silicon; or The chip substrate adopts an optical polymer substrate.

5. The method for constructing a colloidal photonic crystal array chip according to any one of claims 1 to 4, characterized in that: Step S300 specifically includes: injecting a small amount of photonic crystal dispersion into each array cavity unit by air pressure micro-spraying, capillary injection or confined drop coating technology.

6. A colloidal photonic crystal array chip, characterized in that: The colloidal photonic crystal array chip is constructed using the construction method of any one of claims 1 to 5.

7. A modular integrated application of colloidal photonic crystal array chip, characterized in that: The colloidal photonic crystal array chip according to claim 6 is used for modular integration to form an optical response module, a structural color output module or a coding recognition module.

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