Colloid photonic crystal array chip and construction method and application thereof

Abstract

The invention relates to the technical field of micro-nano manufacturing, photon function material and photoelectric system integration, and discloses a colloid photonic crystal array chip and a construction method and application thereof. The construction method of the colloidal photonic crystal array chip comprises the following steps: preparing colloidal photonic crystal dispersion liquid with particle size of 200-400nm and monodispersity; manufacturing a chip substrate with a regular array cavity structure; respectively injecting the colloidal photonic crystal dispersion liquid into each array cavity unit of the regular array cavity structure of the chip substrate; controlling the temperature and humidity environment, evaporating and drying to enable the colloidal particles to be self-assembled into a film; and a flexible film or a glass layer is arranged on the surface of the chip substrate for packaging, so that the photonic crystal array chip with a stable structure is formed. The device has the advantages of being high in assembly precision, high in color uniformity, good in structural stability and the like, and can be widely applied to intelligent sensing, optical labels, color display, biological recognition and other scenes.

Description

Technical Field

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

[0002] Colloidal photonic crystal materials are optical functional materials composed of periodically arranged colloidal microspheres. Their unique photonic bandgap characteristics and structural color effects make them show important application potential in fields such as display technology, optical sensing, laser design, and information encryption. The existence of the photonic bandgap enables this material to selectively reflect light of specific wavelengths, thereby generating bright structural colors, and it does not rely on chemical dyes, having advantages such as environmental protection and anti-fading.

[0003] However, the existing technology still has significant limitations, restricting the practical application process of colloidal photonic crystal materials. The specific technical difficulties are as follows: 1. Insufficient arrayed chip-level construction: Current processes are difficult to achieve precise positioning and distribution control of droplets in a high-resolution array, easily causing edge effects or non-uniform deposition, affecting the periodic arrangement of photonic crystals, and resulting in inconsistent optical properties between units.

[0004] 2. Defects in film-forming quality: Colloidal droplets are prone to cracking, the coffee ring effect, or non-periodic aggregation during the local film-forming process, destroying the long-range ordered structure, resulting in a decrease in structural color saturation or wavelength shift. Existing methods such as annealing and solvent regulation still cannot generally solve this problem.

[0005] 3. Lack of modular integration technology: There is a lack of packaging schemes compatible with functional devices, and existing packaging processes are difficult to balance long-term stability and optical performance retention, restricting their application in complex scenarios. Summary of the Invention

[0006] The present invention provides a colloidal photonic crystal array chip, a construction method, and applications, which combine the processes of controllable droplet positioning, local film-forming, self-assembly, and device-level packaging, and have the advantages of high assembly accuracy, strong color uniformity, and good structural stability. They can be widely applied to scenarios such as intelligent sensing, optical tags, color displays, and biometric identification to solve the technical problems of the preparation of existing colloidal photonic crystal materials, insufficient arrayed chip-level construction, defects in film-forming quality, and lack of modular integration technology.

[0007] According to one aspect of the present invention, a method for constructing a colloidal photonic crystal array chip is provided, including the following steps: S100, preparing a colloidal photonic crystal dispersion with a particle size of 200 nm - 400 nm and monodispersity; S200, fabricating 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 respectively; S400, controlling the temperature and humidity environment, evaporating and drying to enable the colloidal particles to self-assemble into a film; S500, setting a flexible film or a glass layer on the surface of the chip substrate for encapsulation to form a structurally stable photonic crystal array chip.

[0008] Further, in step S100, the particles in the colloidal photonic crystal dispersion are selected from polystyrene or SiO2 nanoparticles.

[0009] Further, a microfluidic emulsion polymerization technique is used to prepare colloidal particles of polystyrene or SiO2 nanoparticles with a particle size of 200 nm - 400 nm and a PDI < 0.1, which are dispersed in pure water or a mixed solvent of ethanol and water to form a stable colloidal dispersion.

[0010] Further, in step S200, the material of the chip substrate is selected from PDMS, glass, silicon or an optical polymer; or the chip substrate adopts an optical polymer substrate.

[0011] Further, the diameter of the array cavity is 100 μm - 300 μm, and the depth is 10 μm - 100 μm.

[0012] Further, step S300 is specifically: injecting a trace amount of the photonic crystal dispersion into each array cavity unit respectively by means of pneumatic microspray, capillary injection or confined drop coating technology.

[0013] Further, in step S400, the self-assembly film formation process is carried out under the conditions of a temperature of 40 °C - 60 °C and a relative humidity of 30% - 50%.

[0014] Further, in step S500, the encapsulation method is UV curable resin, low-temperature hot melt adhesive or glass lamination.

[0015] According to another aspect of the present invention, a colloidal photonic crystal array chip is also provided, which is constructed by using the above method for constructing a colloidal photonic crystal array chip.

[0016] According to another aspect of the present invention, a modular integrated application of a colloidal photonic crystal array chip is also provided, using the above colloidal photonic crystal array chip for modular integration to form an optical response module, a structural color output module or a coding and recognition module.

[0017] The present invention has the following beneficial effects: The construction method of the colloidal photonic crystal array chip of the present invention. The particle size of 200nm - 400nm in the colloidal photonic crystal dispersion 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 physical confinement space is provided for the positioning of the colloidal photonic crystal dispersion; for the array cavity structure, the microcavity size matches the colloidal particles, promoting close packing 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 restrict 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 that it is difficult to achieve precise droplet positioning in a high-resolution array by traditional methods from the physical structure. By controlling the temperature and humidity environment, the colloidal particles are self-assembled into a film; through temperature and humidity control, slow evaporation induces the colloidal particles to self-assemble into a face-centered cubic (FCC) or hexagonal close-packed (HCP) structure in the microcavities, optimizing the optical performance; under the confinement of the regular array cavity, the colloidal dispersion is restricted by the cavity wall during the evaporation and drying process, and the evaporation kinetics tend to be uniform, avoiding the common coffee ring effect of traditional open droplets; at the same time, the precise regulation of the temperature and humidity environment enables the 200nm - 400nm colloidal particles to slowly and orderly self-assemble into a periodically arranged 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 encapsulation process, the chip substrate surface is encapsulated by setting a flexible film or a glass layer, 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 of which 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; directly solving the problem of the lack of reliable modular encapsulation in the prior art, enabling the photonic crystal array to be compatible and integrated with various functional devices. The construction method of the colloidal photonic crystal array chip provided by the present invention realizes high-precision array construction, stable film formation and reliable encapsulation through the synergistic effect of specific process steps; the regular array cavity structure directly determines 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 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 applied to scenarios such as intelligent sensing, optical tags, color displays and biometric identification.

[0018] In addition to the purposes, features and advantages described above, the present invention has other purposes, features and advantages. The present invention will be further described in detail below. Description of the Drawings

[0019] The accompanying drawings, which form a part of the present invention, are used to provide a further understanding of the present invention. The schematic embodiments and descriptions thereof are used to explain the present invention and do not unduly limit the present invention. In the drawings: Figure 1 is a schematic structural diagram of a passive protective film on the chip surface of a preferred embodiment of the present invention; Figure 2 is a schematic cross-sectional structural diagram of a module-level security package based on a flexible film of a preferred embodiment of the present invention. Detailed Description of the Invention

[0020] The following provides a detailed description of the embodiments of the present invention, but the present invention can be implemented in many different ways defined and covered by the following. Unless otherwise specified, the raw materials and reagents used in the following embodiments are commercially available products or can be prepared by known methods.

[0021] The construction method of the colloidal photonic crystal array chip in this embodiment includes the following steps: S100, preparing a colloidal photonic crystal dispersion with a particle size of 200 nm - 400 nm and monodispersity; S200, fabricating 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 to enable the colloidal particles to self-assemble into a film; S500, setting a flexible film or a glass layer on the surface of the chip substrate for encapsulation to form a structurally stable photonic crystal array chip. In the construction method of the colloidal photonic crystal array chip of the present invention, the particle size of 200 nm - 400 nm of the colloidal photonic crystal dispersion determines the position of the photonic band gap, and the monodispersity ensures the structural color purity. By fabricating a chip substrate with a regular array cavity structure, a physical confinement space is provided for the positioning of the colloidal photonic crystal dispersion; for the array cavity structure, the microcavity size matches the colloidal particles, promoting close packing 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 restrict 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 that it is difficult to achieve precise positioning of droplets in a high-resolution array by traditional methods from the physical structure. By controlling the temperature and humidity environment, the colloidal particles are self-assembled into a film; through temperature and humidity control, slow evaporation induces the colloidal particles to self-assemble into a face-centered cubic (FCC) or hexagonal close-packed (HCP) structure in the microcavities, optimizing the optical performance; under the confinement of the regular array cavity, the colloidal dispersion is restricted by the cavity wall during the evaporation and drying process, and the evaporation kinetics tends to be uniform, avoiding the common coffee ring effect of traditional open droplets; at the same time, the precise regulation of the temperature and humidity environment enables the 200 nm - 400 nm colloidal particles to slowly and orderly self-assemble into a periodically arranged 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 encapsulation process, by setting a flexible film or a glass layer on the surface of the chip substrate for encapsulation, mechanical protection and environmental isolation are provided for the photonic crystal array; the flexible film can meet the integration requirements of bending or flexible devices, while the glass layer can provide rigid protection, and 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; directly solving the problem of the lack of reliable modular encapsulation in the prior art, enabling the photonic crystal array to be compatible and integrated with various functional devices.The method for constructing a colloidal photonic crystal array chip provided by the present invention realizes high-precision array construction, stable film formation, and reliable encapsulation through the synergistic action of specific technological steps; the regular array cavity structure directly defines the positioning accuracy of droplets, the self-assembly process under temperature and humidity control directly determines the orderliness of film formation, and the selection of the encapsulation layer is directly related to environmental stability; the synergistic action of each step realizes the high precision, high stability, and application compatibility of the colloidal photonic crystal array chip; it can be widely applied to scenarios such as intelligent sensing, optical tags, color displays, and biometric identification.

[0022] In this embodiment, in step S100, polystyrene (PS) or silicon dioxide (SiO2) nanoparticles are selected as the core materials of the colloidal photonic crystal dispersion; the particle size ranges of PS particles and SiO2 nanoparticles (200nm–400nm) directly correspond 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 for specific colors in applications such as display and sensing, and realizing precise regulation of the photonic bandgap; the refractive indices of PS and SiO2 both form a significant refractive index difference with the air medium or water medium, enhancing the Bragg scattering effect, thereby improving the saturation and brightness of the structural color and achieving a high refractive index contrast. PS particles or SiO2 particles can be prepared into a monodisperse (particle size deviation <5%) colloidal solution through emulsion polymerization or the Stöber method. Monodisperse particles can ensure orderly arrangement during the evaporation-induced self-assembly process and are more likely to form a face-centered cubic (FCC) or hexagonal close-packed (HCP) long-range ordered structure, avoiding the generation of polycrystalline domains or defects. The hydrophobic surface of PS particles can be modified with octadecyltrichlorosilane (OTS) etc. to regulate the wettability with the substrate and inhibit 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 grafting antibodies). PS and SiO2 are resistant to water, oxygen, and weak acids and bases at room temperature, ensuring that the colloidal photonic crystal dispersion does not agglomerate or degrade during storage and processing; the flexible characteristics of PS particles are suitable for flexible device encapsulation (such as PDMS substrate) and are not easily broken under bending conditions; the high hardness of SiO2 particles is suitable for rigid encapsulation (such as a glass layer to provide mechanical protection). PS particles or SiO2 particles spontaneously and orderly stack during confined evaporation, reducing cracking and non-periodic aggregation; for array construction, the surface chemical properties of the particles (such as hydrophobic or hydrophilic modification) assist in the precise filling of microcavities by droplets; for encapsulation requirements, the intrinsic stability of the materials (PS is flexible, SiO2 is hard) directly matches the performance requirements of the encapsulation layer. Selecting PS particles or SiO2 nanoparticles to achieve precise regulation of structural color through the correlation between particle size and optical properties; using monodispersity and surface chemistry to ensure high-quality self-assembly; relying on the intrinsic properties of the materials to meet the requirements of different encapsulation scenarios; this selection directly matches the technical goals of array construction, film formation optimization, and encapsulation stability.

[0023] In this embodiment, microfluidic emulsion polymerization technology is used to prepare colloidal particles of polystyrene or SiO2 nanoparticles with a particle size of 200 nm - 400 nm and PDI < 0.1, which are dispersed in pure water or an ethanol-water mixed solvent to form a stable colloidal dispersion. Microfluidic emulsion polymerization technology is used to prepare highly monodisperse (PDI < 0.1) polystyrene (PS) or silica (SiO2) nanoparticles, which are dispersed in pure water or an ethanol-water mixed solvent to form a stable colloidal dispersion. By precisely controlling the flow rates of the two phases, the interfacial shear force, and the reaction time, the microfluidic technology can prepare PS particles or SiO2 nanoparticles with a uniform particle size (PDI < 0.1), and the particle size is 200 nm - 400 nm; the monodispersity directly determines the quality of the long-range ordered structure formed by the colloidal particles during the self-assembly process, avoiding the generation of polycrystalline domains or defects, thereby improving the purity and consistency of the structural color; the particle size range of 200 nm - 400 nm precisely matches the visible light band, and the monodispersity (PDI < 0.1) ensures the narrowing of the photonic bandgap and a significant reduction in the full width at half maximum of the reflection peak, enhancing the color saturation. The pure water system is suitable for hydrophilic SiO2 particles, and the high-polarity solvent promotes the electrostatic stability of the particles, preventing agglomeration during storage; for the ethanol-water mixed solvent, the addition of ethanol can adjust the wettability of the hydrophobic surface of the PS particles, improve the uniformity of droplet spreading during microcavity filling, and reduce the coffee ring effect caused by contact line pinning; the addition of ethanol can accelerate the evaporation rate (the evaporation of pure water is slow and prone to particle migration), adapt to the temperature and humidity control process, and enable the particles to stack more rapidly and orderly under microcavity confinement. Microfluidic emulsion polymerization can continuously produce highly monodisperse particles, overcoming the batch difference problem of traditional emulsion polymerization, and providing a stable raw material source for chip-level array construction; the pure water system is compatible with hydrophilic encapsulation materials (such as SiO2 glass layers); the ethanol-water system is suitable for hydrophobic flexible films (such as PDMS), and there is no residue after solvent evaporation, avoiding pores or debonding at the encapsulation interface. For film formation defects, monodisperse particles (PDI < 0.1) and solvent evaporation regulation synergistically inhibit the coffee ring and cracking; for array construction, the stable dispersion ensures uniform droplet concentration during microcavity filling, avoiding performance fluctuations between units; for encapsulation requirements, the solvent selection directly matches the subsequent encapsulation process (such as the ethanol-water system adapting to the curing temperature of PDMS). By combining microfluidic emulsion polymerization technology with a pure water or ethanol-water solvent system, it is possible to optimize the optical properties, and monodisperse particles (PDI < 0.1) ensure narrow-bandgap and high-saturation structural colors; achieve improved process stability, and the solvent selection directly solves the problems of droplet filling and evaporation control; as the basis for large-scale production, microfluidic technology provides uniform raw materials for chip-level applications.

[0024] In this embodiment, in step S200, the material of the chip substrate is selected from PDMS, glass, silicon, or optical polymer; or the chip substrate adopts an optical polymer substrate. PDMS and optical polymers (such as PMMA) have high light transmittance, ensuring distortion-free display of the photonic crystal structural color; glass and silicon wafers provide a super-smooth surface, reducing light scattering loss; silicon substrates are particularly suitable for multi-functional devices that require subsequent microelectronic integration. PDMS can achieve a microcavity array with an accuracy of 1μm - 100μm through soft lithography; glass / silicon supports photolithography and etching processes, suitable for fabricating high-precision nanoscale cavities; optical polymers can be fabricated by hot embossing or injection molding, 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 the uniform spreading of water-based dispersions; surface energy matching can optimize the self-assembly orientation of colloidal particles (such as FCC or HCP). PDMS is suitable for flexible wearable devices; glass or silicon provides rigid support with strong anti-deformation ability; optical polymers (such as PMMA) balance flexibility and dimensional stability. Attention should be paid to the thermal matching of PDMS with the encapsulation layer; the thermal expansion behavior of glass is consistent with that of SiO2 particles; silicon is suitable for high-temperature process integration. The surface of PDMS can be hydrophilically modified by oxygen plasma treatment; the surface of glass or Si is easily silanized; the wettability of optical polymers can be improved by UV ozone treatment.

[0025] In this embodiment, the diameter of the array cavity is 100 μm - 300 μm, and the depth is 10 μm - 100 μm. The cavity volume of the array cavity matches the surface tension of the colloidal photonic crystal dispersion liquid to ensure that each cavity forms an independent droplet; the lower diameter limit of 100 μm avoids the filling difficulty caused by the capillary effect; the upper diameter limit of 300 μm prevents the gravity from destroying the droplet stability; thus, precise control of the droplet volume is achieved. The depth design of 10 μm - 100 μm forms a specific aspect ratio (0.03 - 1); the shallow cavity (10 μm - 30 μm) accelerates the solvent evaporation and is suitable for rapid self-assembly; the deep cavity (50 μm - 100 μm) delays the evaporation and promotes a more ordered particle arrangement; the diameter-to-depth ratio (3:1 to 30:1) optimizes the Marangoni convection and suppresses the coffee ring effect; thus, the evaporation kinetics is regulated. The cavity diameter limits the size of the colloidal particle self-assembly domain, and can adaptively achieve monolayer arrangement and controllable growth of multiple crystal domains according to the particle size distribution. The depth direction restricts the number of particle stacking layers, thereby balancing the optical intensity and the response speed, and thus realizing the control of the photonic crystal structure. A diameter > 100 μm ensures that a complete interference pattern is formed in a single cavity within the visible light range, and a depth > 10 μm provides sufficient optical path to enhance the Bragg reflection intensity; a 300 μm diameter is close to the human eye resolution limit, achieving visual uniformity. The diameter of the array cavity of 100 μm - 300 μm is adapted to the accuracy of conventional lithography / microfabrication processes, and the depth of 10 μm - 100 μm matches the thickness of the standard SU-8 photoresist; this size range allows the use of low-cost contact exposure equipment for processing, ensuring process compatibility. A 100 μm cavity is suitable for high-density integration; a 300 μm cavity is convenient for subsequent functional modification (such as biological probe fixation); a 10 μm shallow cavity is suitable for an ultrafast response sensor; a 100 μm deep cavity enhances the mechanical strength; this size design solves the array problem by physical confinement, preventing crosstalk between units through clear boundaries, solves the film formation 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 sizes.

[0026] In this embodiment, step S300 is specifically as follows: a trace amount of photonic crystal dispersion is injected into each array cavity unit by air pressure micro-spraying, capillary injection or confined drop coating technology. Air pressure micro-spraying technology generates trace droplets through piezoelectric drive or pneumatic nozzles to fill the cavity in a non-contact manner to avoid cross contamination; the inkjet accuracy (±2μm) ensures that the droplets strictly fall into the cavity with a diameter of 100μm-300μm, solving the positioning deviation problem of traditional drop coating. Capillary injection technology uses the capillary force of a hydrophilic cavity (such as a glass or SiO2 substrate) to spontaneously suck liquid, or the confined effect of a hydrophobic cavity (such as PDMS) to achieve self-stop filling; the height of the liquid column (10μm-100μm) is directly controlled by the cavity depth, and the volume error is <5%. Confined drop coating technology achieves selective wetting on the hydrophobic-hydrophilic patterned surface through micro-needle contact dispensing, and the droplets are automatically limited to the center of the cavity due to surface energy constraints. It can achieve high-precision droplet positioning and volume control, overcome the problems of inaccurate droplet positioning and crosstalk between units in array construction, and thus meet the process requirements of high-resolution arrays. The instantaneous impact force of air pressure micro-spraying breaks up particle migration, and the continuous wetting balance evaporation rate of capillary injection can reduce edge deposition, promote the uniform distribution of colloidal particles (200nm-400nm) in the cavity, and inhibit the coffee ring effect. Confined drop coating makes the droplet spreading thickness uniform through surface energy matching (such as hydrophilic cavity and water-based dispersion), and cooperates with subsequent temperature and humidity control to achieve slow and orderly self-assembly, avoiding cracking and non-periodic aggregation. Reduce film defects (cracks, coffee rings) from the filling source and improve the color quality of photonic crystal structure. Air pressure micro-spraying is suitable for high-speed array filling of hard 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 can adapt to different substrate materials. The parallel operation of multiple air pressure micro-spray nozzles or batch impregnation of capillary injection significantly improves the preparation efficiency of chip-level arrays and can support high-throughput production. It provides a scalable process foundation for modular system integration and meets the production capacity requirements of actual application scenarios.

[0027] In this embodiment, in step S400, the self-assembled film formation process is carried out under the conditions of a temperature of 40°C–60°C and a relative humidity of 30%–50%. The self-assembled film formation process controls the temperature at 40°C–60°C to maintain the evaporation rate of the solvent (water or ethanol) within an optimized range; at 60°C, the water evaporation rate is about 5 times higher than that at room temperature, but boiling disturbance can be avoided, and the ethanol mixed solvent reaches an azeotropic equilibrium at 50°C; the self-assembled film formation process controls the humidity at 30%–50%. A low humidity environment of 30% is conducive to accelerating evaporation and is suitable for the complete drying of deep cavities (50μm–100μm), and a humidity of 50% is conducive to suppressing excessive surface drying and preventing cracking of shallow cavities (10μm–30μm); a humidity of 40% is more conducive to achieving a uniform advancement of the evaporation front. The optimization of colloidal particle self-assembly is that within the temperature range of 40°C–60°C, the higher the temperature, the higher the Brownian motion rate of the colloidal particles (200nm–400nm), which in turn promotes the formation of the FCC structure; under the thermodynamic equilibrium state, the van der Waals force and electrostatic repulsion force between particles reach the best balance; in a relative humidity environment of 30%–50%, the capillary force stabilizes the particle spacing and keeps it at a spacing of about 1 particle diameter, promoting ordered packing. The humidity environment maintains the continuity of the liquid film, reduces cracks caused by drying stress, has a small temperature gradient, and can avoid non-uniform deposition caused by Marangoni convection; the evaporation rate matches the particle diffusion rate. The constant temperature environment ensures that the evaporation behavior of each unit is consistent, and the humidity control makes the drying time difference of cavities with different depth-to-width ratios small; the temperature-humidity co-regulation realizes the matching of the evaporation rate and the particle sedimentation rate, a small gas-liquid interface energy gradient, and a large particle packing density; the low-temperature (<60°C) process is compatible with polymer substrates such as PDMS, and the gradual drying avoids the generation of microcracks at the encapsulation interface.

[0028] In this embodiment, in step S500, the encapsulation methods include UV-curable resin, low-temperature hot melt adhesive, or glass lamination. For UV-curable resin encapsulation, ultraviolet light is used to initiate resin crosslinking and curing, forming a transparent protective layer on the surface of the photonic crystal. The curing process is completed at room temperature to avoid damaging the ordered arrangement structure of the colloidal particles at high temperatures. The refractive index of the resin matches that of PS or SiO2, controlling the interfacial reflection loss below 5% and maintaining the structural color saturation. The three-dimensional crosslinked network mechanically fixes the positions of the colloidal particles, preventing lattice expansion or cracking caused by humidity changes. The crosslinked and cured resin layer isolates water and oxygen permeation, solving the environmental stability problem. The characteristic of a curing shrinkage rate <3% avoids encapsulation stress from damaging the microcavity array structure. For low-temperature hot melt adhesive encapsulation, a thermoplastic polymer (such as EVA) with a melting temperature of 80°C - 120°C is used for encapsulation. The low-temperature hot pressing process does not cause the glass transition of the colloidal particles, thus maintaining the optical properties of the photonic crystal. The molten hot melt adhesive can completely fill the microcavity gaps, eliminating light scattering caused by air gaps. The elastic modulus matches that of a flexible substrate (such as PDMS), tolerating bending deformation. After the hot melt adhesive cools and cures, it forms a physical barrier to prevent mechanical friction from damaging the microcavity unit. The intrinsic hydrophobicity of the material can resist the erosion of a humid environment. For glass lamination encapsulation, hard encapsulation is achieved through anodic bonding or optical adhesive lamination. The extremely high light transmittance and surface flatness of the glass maximize the retention of the structural color characteristics. The airtight encapsulation provides long-term environmental stability. The thermal expansion coefficient matches that of a silicon substrate or a glass substrate, avoiding interface delamination caused by thermal cycling. The rigid support of the hard glass inhibits crack propagation caused by internal stress in the thin film. Anodic bonding can be directly compatible with semiconductor processes to achieve optoelectronic integration.

[0029] The colloidal photonic crystal array chip of this embodiment is constructed using the above method for constructing a colloidal photonic crystal array chip.

[0030] For the modular integrated application of the colloidal photonic crystal array chip of this embodiment, the above colloidal photonic crystal array chip is used for modular integration to form an optical response module, a structural color output module, or a coding and recognition module.

[0031] In implementation, a method for constructing a colloidal photonic crystal array chip based on colloidal photonic crystals and its integrated application in an optical module are provided. The method first prepares a colloidal photonic crystal dispersion liquid with monodisperse particle sizes, and guides the liquid droplets into the pre-designed microstructural chip array units through methods such as drop coating and confined self-assembly. The liquid droplets spontaneously form a film in the local area to form a periodic structural color film. Subsequently, it is encapsulated with a flexible encapsulation material to construct a photonic crystal array module that can stably output reflected structural colors. This technical solution combines processes such as controllable droplet positioning, local film formation, self-organized assembly, and device-level encapsulation, and has the advantages of high assembly accuracy, strong color uniformity, and good structural stability, and is widely applicable to scenarios such as intelligent sensing, optical tags, color displays, and biometric identification.

[0032] The method for constructing a photonic crystal array chip based on colloidal photonic crystals comprises the following steps: (1) Preparation of photonic crystal dispersion: Polystyrene or SiO2 colloidal particles with a particle size of 200nm-350nm and PDI <0.1 are prepared by microfluidic emulsion polymerization technology and dispersed in pure water or ethanol-water mixed solvent to form a stable colloidal dispersion; (2) Array chip design and construction: Design and prepare chips with regular array microcavity structures (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; (3) Droplet deposition and self-assembly: A small amount of photonic crystal dispersion is precisely injected into the microcavity unit through air pressure micro-spraying, 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; (4) Array fixation and packaging: Cover the array with a transparent flexible film or glass cover for packaging. The packaging method can be lamination, PDMS lamination, UV curing glue or low-temperature hot melt bonding; (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.

[0033] Specifically, the 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.

[0034] 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.

[0035] 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; sensor elements to convert detection signals into optical codes.

[0036] 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.

[0037] Specifically, when the colloidal photonic crystal array chip integrates the sensing element, the photonic crystal structure is changed by the sensing signal to output a recognizable optical code.

[0038] Embodiment 1: (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%.

[0039] (2) Preparation of chip array structure: An array structure with a pore diameter of 200 μm, a depth of 50 μm, and an array period of 300 μm × 300 μm was etched on the surface of the PDMS elastomer by laser microfabrication technology to form a regularly arranged circular cavity array.

[0040] (3) Droplet injection and confined assembly: A precision micro syringe was used to control the injection of 0.4 μL of colloidal dispersion into each array unit, and it was placed in a constant temperature and humidity chamber and naturally dried for 12 hours at 50 °C and a relative humidity of 40%. During the drying process, the colloidal particles spontaneously assembled in the confined space to form a photonic crystal structure.

[0041] (4) Encapsulation and fixation: A UV-curable transparent resin (such as NOA63) was drop-coated on the surface of the dried array chip, covered with a glass slide, and cured and encapsulated under ultraviolet light irradiation.

[0042] (5) Performance detection: The array chip was measured using a reflection spectrometer, and the reflection peak positions were concentrated in the range of 560 nm - 580 nm, indicating that the crystal arrangement was regular and had an obvious structural color; the SEM image showed that the crystal structure in the array was a typical hexagonal close-packed arrangement.

[0043] Example 2: (1) Preparation of array chip: The manufacturing method was the same as that in Example 1. A photonic crystal array chip was made using polystyrene particles, and the array specifications were 8 × 8, with a total of 64 color-emitting units.

[0044] (2) Flexible circuit module design: A flexible printed circuit board (FPC) was used as the carrier platform, and a micro LED array was embedded to provide controllable irradiation light sources with different wavelengths (450 nm, 520 nm, 630 nm); the circuit board was connected to a communication module and a temperature and humidity sensor.

[0045] (3) Chip encapsulation and integration: The dried photonic crystal array chip was fixed on the module and sealed by edge encapsulation with hot melt adhesive. The LED array was located below the chip to provide backlight excitation, and the sensor collected the surrounding environmental parameters.

[0046] (4) Function verification: The module was placed in different humidity environments (30%, 60%, 90%), and the structural color showed a reversible shift, with the reflection peak moving from 540 nm to 590 nm; at the same time, by controlling the LED switch, color recognition and synchronous reading of environmental data were achieved.

[0047] (5) Application scenarios: The module can be used in scenarios such as environmental visualization sensing tags, wearable structural color identifiers, and smart product identity anti-counterfeiting tags, showing good responsiveness and stability.

[0048] Additionally, 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. The specific steps are as follows: 1. Preparation of colloidal crystal film: Precise control of the arrangement of colloidal particles is achieved through microfluidic technology to form a colloidal crystal film with stable optical properties. The preparation process of the colloidal crystal film is as follows: Preparation of colloidal particles: High-quality nanoparticles (such as polystyrene or silica) are used to prepare a colloidal particle solution to ensure the uniformity and stability of the particles.

[0049] Injection of solution into the 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.

[0050] Microfluidic regulation of particle arrangement: By adjusting the flow rate and hydrodynamic effects of the microfluidic chip, the arrangement of particles is precisely controlled to self-assemble into a colloidal crystal film with a periodic structure. Microfluidic technology can ensure the precise arrangement of particles at the microscale.

[0051] Film curing and stability testing: After the film is formed, curing treatment is carried out to ensure its structural stability, and optical performance stability testing is performed.

[0052] The combination of microfluidic technology and colloidal crystal film. Microfluidic technology can precisely control the flow of colloidal particles in the microchannels, ensuring the consistency of the optical properties and structure of the film, thereby ensuring the stability of each film in different environments. Compared with traditional film preparation methods, the introduction of microfluidic technology enables more precise particle arrangement, and the optical properties of the film can be maintained consistently in large-scale production. Through this precise control, the present invention can generate optical "fingerprints" with high randomness and uniqueness, significantly improving the security of the PUF system.

[0053] 2. Design of optical PUF system: The prepared colloidal crystal film is applied to the PUF system, and a unique authentication code is generated through its unique optical "fingerprint" for encryption and anti-counterfeiting purposes. The design of the optical PUF system is as follows: Microfluidic film optical sensor (colloidal crystal film): The colloidal crystal film serves as an optical sensor. A light source (laser or light-emitting diode) is irradiated onto the film surface, and the optical "fingerprint" of the film exhibits unique optical properties according to its micro-structure.

[0054] Light source and optical sensor: A laser or light-emitting diode is used as the light source to generate an optical signal through the reflection or transmission characteristics of the thin film. An optical sensor (such as a photodetector) receives the reflected or transmitted light and identifies the optical "fingerprint" of the thin film by measuring the optical signal at a specific wavelength.

[0055] Generation and encryption of unique optical "fingerprint": The optical characteristics read by the optical sensor are converted into unique "fingerprint" information. This "fingerprint" is used to generate encrypted information, which can be used as the authentication for the encryption module or the key for the anti-counterfeiting label.

[0056] Security authentication and encryption applications: The finally generated optical "fingerprint" is applied to the security authentication system or encryption module to provide a unique authentication code for different devices and enhance the security of the devices.

[0057] Module-level security encapsulation technology based on flexible composite thin films, integrating advanced composite thin film materials and highly reliable PUF extraction technology, with an independently controllable process for constructing a colloidal photonic crystal array chip based on colloidal photonic crystals, constructing a flexible composite thin film with random texture characteristics, and then forming a module-level security encapsulation solution, such as Figure 1 shown.

[0058] To ensure the protection effect of module-level security encapsulation, it is necessary to conduct a system design on the wrapping method of the flexible thin film and the structure of the security module. The structure of the flexible thin film and the security module constructed by using the method for constructing a colloidal photonic crystal array chip based on colloidal photonic crystals ensures that the characteristics of the thin film will inevitably be affected after the attacker disassembles the flexible thin film, and thus the PUF key based on the flexible composite thin film cannot be restored. The schematic cross-sectional view of the module-level security encapsulation based on the flexible composite thin film is as Figure 2 shown. The flexible thin film wraps the module and the measurement circuit together, and the internal connections are made through board-level interconnection signals. If the attacker disassembles the flexible thin film, it will cause deformation of the thin film, thereby causing changes in the characteristics of the thin film and resulting in the failure of key restoration.

[0059] Matters not covered in this invention are well-known technologies.

[0060] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, 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, it should be considered as the scope recorded in this specification.

[0061] The embodiments described above merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the appended claims.

[0062] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for constructing a colloidal photonic crystal array chip, characterized in that, It includes the following steps: S100. Prepare a colloidal photonic crystal dispersion with a particle size of 200 nm - 400 nm and monodispersity; S200. Fabricate a chip substrate with a regular array cavity structure; S300. Inject the colloidal photonic crystal dispersion into each array cavity unit of the regular array cavity structure of the chip substrate respectively; S400. Control the temperature and humidity environment, evaporate and dry to make the colloidal particles self-assemble into a film; S500. Set a flexible thin film or a glass layer on the surface of the chip substrate for encapsulation to form a structurally stable photonic crystal array chip.

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

3. The method for constructing the colloidal photonic crystal array chip according to claim 2, wherein Prepare colloidal particles of polystyrene or SiO2 nanoparticles with a particle size of 200 nm - 400 nm and PDI < 0.1 by microfluidic emulsion polymerization technology, and disperse them in pure water or an 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 material of the chip substrate is selected from PDMS, glass or silicon; or The chip substrate uses an optical polymer substrate.

5. The method for constructing the colloidal photonic crystal array chip according to claim 4, characterized in that The diameter of the array cavity is 100 μm - 300 μm, and the depth is 10 μm - 100 μm.

6. The construction method of the colloidal photonic crystal array chip according to any one of claims 1 to 5, characterized in that, Step S300 is specifically: Inject a trace amount of the photonic crystal dispersion into each array cavity unit respectively by pneumatic microspray, capillary injection or confined drop coating technology.

7. The method for constructing a colloidal photonic crystal array chip according to any one of claims 1 to 5, characterized in that In step S400, the self-assembly film formation process is carried out under the conditions of a temperature of 40°C - 60°C and a relative humidity of 30% - 50%.

8. The method for constructing a colloidal photonic crystal array chip according to any one of claims 1 to 5, characterized in that, In step S500, the encapsulation method is UV curable resin, low-temperature hot melt adhesive or glass lamination.

9. A colloidal photonic crystal array chip, characterized in that, It is constructed by using the method for constructing a colloidal photonic crystal array chip according to any one of claims 1 to 8.

10. Modular integrated application of a colloidal photonic crystal array chip, characterized in that, Use the colloidal photonic crystal array chip according to claim 9 for modular integration to form an optical response module, a structural color output module or a coding recognition module.

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