Preparation method and application of liquid colloidal crystal thin film materials

Abstract

The present invention relates to the technical field of optical thin film materials, and discloses a preparation method and application of a liquid colloidal crystal thin film material. The preparation method of the liquid colloidal crystal thin film material comprises the following steps: preparing a monodisperse colloidal particle solution; adopting a dual-channel or multi-channel fluidic structure to optimize the fluid chaos effect and promote the uniform distribution of nanoparticles on the liquid-solid interface; avoiding particle agglomeration or disordered accumulation by precisely controlling the flow rate, pressure gradient and flow channel structure; injecting the colloidal particle solution; after the film is formed, ensuring the stability of the film structure by curing treatment, and obtaining a colloidal crystal film with stable optical properties. Through the integration of fluid mechanics, colloidal chemistry, and interface engineering technology, as well as the combination of microfluidics technology and colloidal crystal thin film technology, the technical bottlenecks of traditional optical thin film materials in structural accuracy, environmental stability and large-scale production have been overcome, providing solutions for high-security optoelectronic encryption, anti-counterfeiting and flexible optoelectronic devices.

Description

Technical Field

[0001] The present invention relates to the technical field of optical thin film materials, and in particular, to a method for preparing a liquid colloidal crystal thin film material. Furthermore, the present invention relates to a method for designing an optical physics unclonable function system utilizing the method for preparing the liquid colloidal crystal thin film material. Furthermore, the present invention relates to an application of the optical physics unclonable function system. Background Art

[0002] In recent years, optical thin film materials have become increasingly valuable in optoelectronic encryption, anti-counterfeiting, and high-security applications. However, their practical application has long been limited by the inherent flaws of traditional preparation techniques. Existing technologies often employ processes such as self-assembly, spin coating, or vertical deposition. These methods face significant bottlenecks in terms of structural control precision, environmental stability, and large-scale production. Specifically,

[0003] 1. Extensive structural control leads to unstable optical performance

[0004] The photonic bandgap (PBG) properties of existing thin-film materials are susceptible to environmental fluctuations such as temperature and humidity. For example, in self-assembled colloidal crystal films, changes in interparticle interactions can cause lattice parameter shifts and significant shifts in the PBG wavelength when exposed to temperature or humidity fluctuations. This instability severely limits the reliability of these materials in applications requiring long-term exposure to complex environments.

[0005] 2. Insufficient structural control accuracy

[0006] Traditional self-assembly techniques rely on natural crystallization during solution evaporation. The arrangement of particles is randomly influenced by factors such as the solvent evaporation rate and the substrate surface energy, making it difficult to achieve long-range ordered periodic structures. Furthermore, the wide particle size distribution and weak interfacial bonding lead to poor consistency in the film's optical response, making it impossible to meet the stringent structural uniformity requirements for high-precision optical "fingerprint" encryption.

[0007] 3. Limited scale production and high costs

[0008] Existing technologies rely on complex process conditions (such as ultra-clean environment, layer-by-layer deposition) and high-precision equipment (such as vacuum coating machines). Single-batch production is time-consuming and has a low yield rate. Summary of the Invention

[0009] The present invention provides a preparation method of liquid colloidal crystal thin film materials, a design method and application of optical physical unclonable function systems, and proposes a preparation method of liquid colloidal crystal thin films based on microfluidic technology. Through multi-channel fluidic structure design, precise control of fluid dynamics and coordinated optimization of interface solidification, it breaks through the bottlenecks of structural disorder, environmental sensitivity and low production efficiency in traditional technologies, and provides a reliable solution for high-security optical encryption and anti-counterfeiting applications.

[0010] According to one aspect of the present invention, a method for preparing a liquid colloidal crystal thin film material is provided, comprising the following steps: S101, preparing a monodisperse colloidal particle solution; S102, adopting a dual-channel or multi-channel flow control structure to optimize the fluid chaos effect and promote the uniform distribution of nanoparticles at the liquid-solid interface; avoiding particle agglomeration or disordered accumulation by precisely controlling the flow rate, pressure gradient and flow channel structure; S103, injecting the colloidal particle solution; S104, after the film is formed, ensuring the stability of the film structure by a curing treatment, thereby obtaining a colloidal crystal film with stable optical properties.

[0011] Furthermore, in step S101, a colloidal particle solution is prepared using nanoparticles, and the nanoparticles are polystyrene nanoparticles or silica nanoparticles; solution method and wet chemical synthesis are used, combined with interface induced assembly technology, to make the nanoparticles uniform in size and have a controllable morphology; and the reaction conditions are optimized to improve the dispersibility and stability of the nanoparticles.

[0012] Furthermore, the preparation of the monodisperse colloidal particle solution in step S101 specifically includes: nanoparticle pretreatment, surface functionalization to enhance stability, solution rheology optimization, and sterilization and storage for future use.

[0013] Furthermore, the dual-channel or multi-channel fluidic structure in step S102 adopts a microfluidic chip, and according to the flow rate and fluid dynamics effect of the microfluidic chip, the multiple tiny channels of the microfluidic chip are adjusted to assemble a colloidal crystal film with a periodic structure, thereby ensuring the precise arrangement of nanoparticles at the microscale.

[0014] Furthermore, the design of the microfluidic chip includes a fractal flow channel structure design for achieving uniform flow velocity distribution, specifically including: tree-like fractal network structure design, including branching level, width contraction ratio and depth gradient design; curvature-induced secondary flow design, including spiral channel unit, Dean vortex intensity and vortex period design.

[0015] Furthermore, the design of the microfluidic chip includes a dynamic flow rate control design for precisely regulating particle movement, specifically including: a multi-stage pressure drive system design, including a core flow pump, a sheath flow pump, and a feedback control design; and a pulse flow field design, including a piezoelectric actuation module, waveform parameters, and effect verification design.

[0016] Furthermore, the design of the microfluidic chip includes particle arrangement control design for constructing periodic structures, specifically including: electric field-assisted assembly, including electrode layout, dielectrophoretic force and arrangement direction control design; magnetofluidic positioning design, including superparamagnetic particles, electromagnetic arrays and dynamic switching design.

[0017] Furthermore, after step S104, the method further includes: S105, performing an optical performance stability test.

[0018] According to another aspect of the present invention, a method for designing an optical unclonable function system is provided, which utilizes the aforementioned method for preparing a liquid colloidal crystal thin film material, comprising the following steps: S201: preparing a colloidal particle solution by using solution-based and wet chemical synthesis methods combined with interface-induced assembly technology to ensure uniform nanoparticle size and controllable morphology; optimizing reaction conditions to improve the dispersibility and stability of the particles, thereby ensuring the reliability and repeatability of the PUF system under different environmental conditions; S202: preparing a liquid colloidal crystal thin film by using a dual-channel or multi-channel fluidic structure to optimize fluid chaos effects and promote uniform distribution of nanoparticles at the liquid-solid interface; precisely controlling the flow rate, pressure gradient, and flow channel structure to avoid particle agglomeration or disordered accumulation, thereby ensuring the stability and consistency of the PUF film structure; S203: detecting the optical fingerprint of the PUF film using an optical sensor by illuminating the film with a laser or a tunable light source and recording the transmitted, reflected, or scattered light signals; extracting the optical data using Fourier transform spectroscopy or photon correlation spectroscopy to generate a unique optical code to ensure high security and non-replicability in encryption and anti-counterfeiting applications.

[0019] According to another aspect of the present invention, an application of an optical-physical unclonable function system is provided. The design method of the optical-physical unclonable function system is adopted in combination with the optical-physical unclonable function system, and optical fingerprints are used for security authentication and anti-counterfeiting, which is applied to anti-counterfeiting labels, intelligent recognition systems or high-security encryption modules.

[0020] The present invention has the following beneficial effects:

[0021] 1. Monodisperse colloidal particle solution: Through surface functionalization and solution rheology optimization, surface charge and polymer chains inhibit the agglomeration caused by van der Waals forces, ensuring the monodispersity of colloidal particles. Monodisperse particles spontaneously form an ordered arrangement by maximizing entropy in the flow field, laying the foundation for subsequent ordered assembly.

[0022] 2. The dual channels of the multi-channel flow control structure and its flow control design are combined with the chaotic mixing effect. The fractal design of the flow channel reduces shear force fluctuations, accurately adjusts the particle migration rate, and achieves uniform distribution of particles at the liquid-solid interface to avoid local agglomeration.

[0023] 3. Use light curing or heat curing to form a cross-linked network to increase the Young's modulus of the film and reduce the band gap offset after wet-heat aging; gradient heating eliminates thermal stress and avoids cracks.

[0024] 4. The microfluidic chaos effect introduces process randomness, which can generate unique optical "fingerprints" with low imitation similarity; the cross-linked structure can withstand extreme humidity, heat and mechanical bending, and has a high performance retention rate.

[0025] 5. Through the integration of fluid mechanics, colloid chemistry, and interface engineering technologies, as well as the combination of microfluidics and colloidal crystal thin film technology, the technical bottlenecks of traditional optical thin film materials in structural accuracy, environmental stability, and large-scale production have been overcome, providing solutions for the new generation of high-security optoelectronic encryption, anti-counterfeiting technology, and flexible optoelectronic devices.

[0026] 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. DETAILED DESCRIPTION

[0027] 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.

[0028] The preparation method of the liquid colloidal crystal thin film material of this embodiment includes the following steps: S101, preparing a monodisperse colloidal particle solution; S102, using a dual-channel or multi-channel flow control structure to optimize the fluid chaos effect and promote the uniform distribution of nanoparticles at the liquid-solid interface; avoiding particle agglomeration or disordered accumulation by precisely controlling the flow rate, pressure gradient and flow channel structure; S103, injecting the colloidal particle solution; S104, after the film is formed, ensuring the stability of the film structure through a curing treatment to obtain a colloidal crystal film with stable optical properties. The present invention's method for preparing liquid colloidal crystal thin film materials utilizes a multi-step synergistic approach based on the principles of fluid dynamics, interface regulation, and structural stabilization, integrating microfluidics with colloidal crystal thin film technology. This method systematically addresses the technical bottlenecks of traditional optical thin film materials in optoelectronic encryption and anti-counterfeiting applications. Through surface functionalization (such as sulfonation or PEG modification) and solution rheology optimization, surface charge and polymer chains in monodisperse colloidal particle solutions inhibit van der Waals-induced aggregation, ensuring the monodispersity of the colloidal particles. The monodisperse particles spontaneously form an ordered arrangement in the flow field through entropy maximization, laying the foundation for subsequent ordered assembly. The dual-channel / multi-channel fluidic design of the multi-channel fluidic structure incorporates chaotic mixing effects (Dean vortices and secondary flow). Fractal flow channel design (such as four-level tree-like branches) reduces shear force fluctuations, precisely regulates particle migration rate, and achieves uniform particle distribution at the liquid-solid interface, avoiding localized agglomeration. The spiral flow channel elements induce Dean vortices, disrupting the laminar boundary layer and improving particle distribution uniformity. Colloidal solution injection and film formation: Continuous sampling in a microfluidic chip is combined with sheath flow ratio control. The sheath flow envelops the core flow, compressing the particle diffusion zone and forming a tightly packed monolayer, achieving uniform film thickness and large-scale continuous fabrication. A piezoelectric actuator generates a pulsed flow field, dynamically regulating the particle deposition rate. Curing treatment uses photocuring or thermal curing to form a cross-linked network, which increases the film's Young's modulus and minimizes bandgap shift after wet-heat aging. Gradient heating eliminates thermal stress and prevents cracking. The combination of monodisperse particles and ordered arrangement reduces the full width at half maximum (FWHM) of the photonic bandgap, minimizing photonic bandgap wavelength shift and achieving high stability. The microfluidic chaotic effect introduces process randomness, generating a unique optical "fingerprint" with low imitation accuracy. The cross-linked structure withstands extreme moisture and heat and mechanical bending, maintaining high performance retention. The microfluidic chip supports parallel multi-channel production (e.g., 16 channels), improving efficiency and reducing costs. Through the integration of fluid mechanics, colloid chemistry, and interface engineering technologies, as well as the combination of microfluidics and colloidal crystal thin film technology, the technical bottlenecks of traditional optical thin film materials in structural accuracy, environmental stability, and large-scale production have been overcome, providing solutions for the new generation of high-security optoelectronic encryption, anti-counterfeiting technology, and flexible optoelectronic devices.

[0029] In this embodiment, the monodisperse colloidal particle solution is prepared in step S101, specifically:

[0030] Reagent preparation:

[0031] Add 3.75 μL of methacrylic acid (MAA) to 5 mL of 0.025 wt% sodium dodecyl sulfate (SDS) aqueous solution and mix well to obtain a MAA / SDS mixed solution. Dissolve 1 g of potassium persulfate (KPS) in 10 mL of ultrapure water to prepare a 0.1 g / mL KPS solution. Set aside 1 mL of styrene.

[0032] Fluidiclab Intelligent Nanoparticle Synthesizer NP-S2 instrument parameter settings:

[0033] (1) Synthesis of PS nanospheres:

[0034] Flow rate ratio: 1:10 (lipid phase: aqueous phase); total flow rate: 10 mL / min; product: 1 mL; pre-waste: 0.6 mL; heating: 60°C; styrene as the lipid phase, MAA / SDS mixed solution as the aqueous phase.

[0035] (2) KPS treatment of PS nanospheres:

[0036] Flow rate ratio: 1:10; total flow rate: 10 mL / min; product: 1.5 mL; pre-waste: 0.6 mL; heating: 80°C; the first step product PS nanospheres as the aqueous phase, 0.1 g / mL KPS solution as the lipid phase.

[0037] Chip used: Fluidiclab MTGL-FL-001 metallic glass chip.

[0038] In this embodiment, in step S101, a colloidal particle solution is prepared using nanoparticles, where the nanoparticles are polystyrene nanoparticles or silica nanoparticles. Solution-based and wet chemical synthesis, combined with interface-induced assembly techniques, are employed to achieve uniform size and controllable morphology in the nanoparticles. Reaction conditions are optimized to improve the dispersibility and stability of the nanoparticles. The purpose of preparing a monodisperse colloidal particle solution in step S101 is to provide highly uniform and stable colloidal units for the subsequent microfluidic assembly process. Through the coordinated regulation of materials chemistry and interface engineering, this systematically addresses technical bottlenecks in traditional processes, such as particle agglomeration, sizing heterogeneity, and poor stability. Particle size and morphology are homogenized. Solution methods (e.g., emulsion polymerization) and wet chemical synthesis (e.g., sol-gel, Stöber methods) precisely control the particle size (e.g., 200±5nm for polystyrene, 300±10nm for silica) and morphology (sphericity >99%), ensuring monodispersity (PDI <0.05). Monodisperse particle growth is achieved by controlling monomer concentration, reaction temperature, and stirring rate. Microemulsion droplets (50nm-200nm in diameter) act as nanoreactors, confining the particle growth space and ensuring size uniformity. Surface functionalization enhances dispersion stability. Surface chemical properties are manipulated through sulfonation (for PS particles) or PEG modification (for SiO2 particles), inhibiting van der Waals-induced aggregation and improving colloidal solution stability. Sulfonation introduces sulfonic acid groups, enhancing Coulomb repulsion between particles. PEG chains form a hydration layer, hindering close contact between particles. Rheological optimization was performed to adapt to the microfluidic process, and rheological modifiers (such as 0.3 wt% HPMC) were added to control the solution viscosity (15 ± 2 mPa·s, shear rate 100 s -1 ), so that it is in line with the shear force of the flow channel of the microfluidic chip (0.1 -10 Matching the flow rate (Pa) of the liquid to ensure orderly particle migration under laminar flow conditions; the non-Newtonian properties of the solution reduce the viscosity of the solution at high shear rates, reducing flow resistance within the flow channel; optimizing the colloid concentration (e.g., PS: 2wt%, SiO2: 4wt%) to balance the interparticle forces with the fluid forces and prevent deposition and clogging. Interface-induced preassembly regulates particle orientation. Introducing amphiphilic molecules (e.g., SDS) or external fields (e.g., ultrasound) into the solution induces particle preassembly at the liquid-liquid or liquid-solid interface, forming short-range ordered structures (e.g., hexagonal close-packed localized domains); particles adsorb at the oil-water interface, reducing the free energy of the system and spontaneously arranging into a monolayer array; ultrasonic cavitation (40kHz, 300W) generates microfluidic disturbances, assisting particle alignment along streamlines. Sterilization and storage ensure production continuity. Sterilization through a 0.22μm filter membrane and nitrogen-filled sealed storage (refrigerated at 4°C) inhibits microbial growth and oxidative degradation, ensuring stable performance during solution storage. The filter membrane pore size is smaller than the bacterial size (>0.5μm), blocking microbial contamination. Nitrogen replaces oxygen, inhibiting particle surface oxidation (e.g., PS sulfonic acid group decomposition rate <0.1% / day).

[0039] Step S101, through the synergistic effect of material synthesis, surface engineering and rheological regulation, provides a colloidal solution with high monodispersity, high stability and strong process adaptability for subsequent microfluidic assembly. It fundamentally solves the structural defects, performance fluctuations and production consistency problems caused by uneven particles in traditional optical films, and is the cornerstone for obtaining high-quality colloidal crystal films. The effect of step S101 is reflected in the coordinated optimization of multi-dimensional technical means to provide a highly controllable colloidal solution system for subsequent processes. The monodispersity of particles is improved, the coefficient of particle size variation (PDI) is reduced to <0.05, and the sphericity of particles is >99%; this eliminates structural defects and improves optical consistency. The stability of the colloidal solution is enhanced, and the absolute value of the Zeta potential is increased from -30mV to -45mV; this suppresses particle agglomeration and ensures process continuity. The rheological properties are adapted to the microfluidic process, and the viscosity is controlled to 15±2mPa·s (shear rate 100s -1 ), shear thinning index > 0.8, and colloid concentration error < 0.5%; this optimizes laminar flow and prevents channel clogging. Interfacial pre-assembly induces an ordered structure, with pre-assembled domains > 50 μm and short-range order (local SAXS peak half-width) < 0.5°, accelerating microfluidic assembly, improving assembly efficiency, and reducing defect density. Long-term storage and batch consistency ensure production stability and minimize raw material waste, with particle size growth < 3 nm within 30 days and batch-to-batch band gap wavelength deviation < 0.5 nm (UV-Vis spectroscopy analysis). An electrostatic-steric synergistic stabilization mechanism (zeta potential + polymer chains) overcomes the limitations of traditional single stabilization modes. Interfacial confinement effects enable precise nanoscale synthesis, addressing the challenge of random particle size distribution. The multi-physics coupling of colloidal solution parameters (viscosity, concentration, pH) with the microfluidic chip enables seamless process integration. An online monitoring and feedback system (such as real-time concentration detection by UV spectroscopy) ensures production consistency and promotes industrialization. Step S101, through the coordination of the entire chain of materials, processes, and equipment, not only solves the problems of uniformity and stability of the colloidal solution itself, but also provides an ideal "raw material library" for subsequent microfluidic assembly. It is the core technical foundation for breaking through the bottleneck of traditional optical thin film technology and realizing the large-scale application of high-performance colloidal crystal films.

[0040] In this embodiment, step S101, preparing a monodisperse colloidal particle solution, specifically includes nanoparticle pretreatment, surface functionalization to enhance stability, solution rheology optimization, and sterilization and storage for future use. Nanoparticle pretreatment: Polystyrene (PS) pretreatment is performed using a solution method (dilution of the emulsion) combined with ultrasonic treatment to ensure particle dispersion. A PS emulsion (10 wt%) is diluted to 2 wt%, SDS is added, and ultrasonic treatment (e.g., 40 kHz, 300 W) is performed for 30 minutes to eliminate weak aggregates (PDI < 0.05). Nanoparticle pretreatment: Silica (SiO2) pretreatment is performed using wet chemical synthesis (e.g., the Stöber method) combined with centrifugation purification. SiO2 particles are prepared using the Stöber method, subjected to multiple centrifugation cycles (e.g., three times at 8000 rpm) to remove impurities, and finally dispersed using a NaOH solution. Surface functionalization enhances stability: PS surface functionalization is performed by introducing charge repulsion through sulfonation. Sulfonation treatment at 65°C for 2 hours achieves a surface charge density of -45 mV. Chemical modification enhances electrostatic stability. Surface functionalization enhances stability: SiO2 surface functionalization, interface-induced assembly (e.g., PEG modification); PEG-Si grafting (1.2 chains / nm²) to create steric hindrance; and colloidal stabilization achieved through molecular grafting. Solution rheology optimization: Optimize reaction conditions (e.g., pH and viscosity) to improve dispersibility. Add HPMC to adjust viscosity to 15 mPa·s; adjust pH to 8.5 (PS) or 10.0 (SiO2) to maintain a zeta potential >40 mV. Control rheological parameters to meet microfluidic requirements. Sterilization, storage, and use are sterilized by 0.22 μm filtration and refrigerated at 4°C under nitrogen. Aseptic handling is consistent with stability assurance measures. Interface-induced assembly technology, combined with interface-induced assembly technology to control particle morphology; using sheath flow ratio (e.g., 5:1), electric field (e.g., AC10V) or magnetic field (e.g., 0.1T) in microfluidic chips to dynamically adjust particle arrangement; surface nanotopology (e.g., 200nm column array) to guide directional assembly; controllable assembly through external fields (flow field, electric field, magnetic field) and surface structure.

[0041] In this embodiment, the dual-channel or multi-channel fluidic structure in step S102 utilizes a microfluidic chip. Based on the flow rate and fluid dynamics of the microfluidic chip, the chip's multiple microchannels are adjusted to assemble a periodic colloidal crystal film, ensuring precise arrangement of nanoparticles at the microscale. The effectiveness of the dual-channel or multi-channel fluidic structure in step S102 is primarily reflected in achieving efficient and orderly assembly of colloidal particles through fluid dynamics optimization and precise microscale control. Particle alignment accuracy is improved. Multi-channel flow control (e.g., a four-stage tree-like fractal flow channel) precisely controls particle migration paths, achieving periodic hexagonal close-packed (hcp) or face-centered cubic (fcc) structures with a lattice constant deviation of less than 2%. Shear gradient control, with a gradient contraction of the channel width (e.g., a contraction ratio of 0.618), evenly distributes shear forces, driving particles to align along streamlines. Secondary flow enhances positioning. Helical flow channels (e.g., a curvature radius of 2 mm) induce Dean vortices (e.g., Dean numbers De = 0.5-5), disrupting the laminar boundary layer and forcing particles to align regularly at the interface. Particle uniformity is enhanced by combining a sheath flow ratio (e.g., core flow:sheath flow = 1:5) with a pulsed flow field (e.g., a piezoelectric actuation frequency of 1 Hz-100 Hz) to achieve uniform particle distribution at the liquid-solid interface. The sheath flow envelops the core flow, compressing the particle diffusion zone to a width of 10 μm, forming a tightly packed monolayer. The pulsed flow field periodically perturbs the particle deposition rate, suppressing localized agglomeration. Agglomeration prevention and defect suppression: Chaotic mixing effects (such as Dean vortices) and surface wettability gradient design (contact angle 30°→110°) eliminate particle agglomeration (aggregate size <500nm) and disordered stacking. Secondary flow breaks aggregates into individual particles. The gradient hydrophilic / hydrophobic surface guides particle adsorption in a targeted manner, avoiding random stacking. Production efficiency and scalability are improved by combining multi-channel parallel design (such as a 16-channel microfluidic chip) with continuous injection (flow rate 0.1μL / min-10μL / min), achieving film preparation rates >10cm² / min. Fractal flow channels evenly distribute the main fluid into multiple branches, achieving simultaneous particle arrangement. Online monitoring feedback: Fiber optic sensors (50μm spacing) monitor flow rate and particle density in real time, dynamically adjusting the sheath flow ratio. Environmental adaptability is enhanced, and the optimized flow channel structure design (such as contraction-expansion unit) combined with dynamic pressure control enables the band gap shift of the film to be less than 2nm (conventionally >10nm) under extreme conditions (85℃ / 85%RH); the periodic flow channel expansion area releases the internal stress of the fluid and reduces the internal stress of the film after curing; the hydrophobic coating (for example, contact angle 110°) blocks the penetration of water molecules and inhibits particle displacement caused by capillary force.Fluid-structure collaborative design, through geometric optimization of fractal flow channels and vortex units, upgrades passive self-assembly to active fluid dynamics control, breaking through the traditional process's reliance on natural crystallization. A dynamic response mechanism, closed-loop control of piezoelectric actuators and online sensors, enables real-time optimization of process parameters to cope with complex fluid environment fluctuations. A breakthrough in large-scale production, multi-channel parallel design and continuous sampling, propels colloidal crystal films from the laboratory to industrial mass production, meeting market demands for high-security anti-counterfeiting and optoelectronic integration. Step S102, through the multi-channel design and fluid dynamics optimization of the microfluidic chip, achieves precise microscale manipulation of colloidal particles, fundamentally resolving the problems of structural disorder, low efficiency, and environmental sensitivity in traditional processes, providing core technical support for the large-scale application of high-performance colloidal crystal films.

[0042] In this embodiment, the design of the microfluidic chip includes a fractal flow channel structure design for achieving uniform flow velocity distribution, specifically including: tree-like fractal network structure design, including branching order, width contraction ratio and depth gradient design; curvature-induced secondary flow design, including spiral channel unit, Dean vortex intensity and vortex period design. In microfluidic chips, the channel size is very small, usually at the micron level. In order to achieve precise fluid control and analysis, the Reynolds number needs to be reduced to the laminar flow region to ensure that the fluid flows stably and layered in the channel to avoid mixing and interference caused by turbulence; the fractal flow channel structure design eliminates the flow velocity difference between the main channel and the branches through the hierarchical diversion design of the tree-like fractal network, ensuring uniform migration of nanoparticles in the flow channel to avoid local accumulation or shear damage; the fractal structure follows the fluid continuity equation (the total flow rate of the fluid in the fractal structure is equal to the sum of the flow rates of each branch, that is, Q =∑Qbranch, the cross-sectional area contraction ratio of each branch matches the flow distribution, thereby reducing the Reynolds number (Re=0.1-10) to the laminar flow region. Shear force gradient control, through the synergistic effect of depth gradient design (main channel 200μm→end 50μm) and width contraction ratio, the shear force gradient ( dτ / dx ) is reduced to <1Pa / mm, reducing the arrangement distortion caused by uneven force on particles; the shear force formula , by reducing the velocity gradient ( dv / dy ) and dynamic viscosity ( μ ) to regulate shear stress. Enhanced mixing and particle dispersion, the Dean vortex induced by the spiral channel (Dean number De = 0.5-5) breaks the laminar boundary layer, increases the particle diffusion coefficient, and eliminates agglomerates; the secondary flow intensity of the Dean vortex , where Re is the Reynolds number, R is the radius of curvature, and d is the channel diameter. The eddy current intensity is controlled by adjusting the R / d ratio (0.5-2). The branch level of the tree-like fractal network structure design adopts a 4-level fractal structure (main channel → 4 branches → 16 branches → 64 branches), and the number of branches at each level is 4 n Exponential growth (n is the number of levels); including: channel design, primary branch, secondary branch, and terminal branch; width contraction ratio, using the golden ratio (0.618) to ensure that the sum of the cross-sectional area of each branch is equal to the cross-sectional area of the upper channel (satisfying flow conservation), calculated as follows:

[0043] ;

[0044] A depth gradient design with a gradual decrease in depth (200μm → 50μm) reduces the channel aspect ratio (from 4:1 to 1:1.6) to prevent particle deposition due to vertical velocity gradients. Grayscale lithography or 3D printing (10μm layer thickness) is used in the manufacturing process to achieve a depth gradient structure. The spiral channel unit for curvature-induced secondary flow design has a curvature radius R = 2mm, a channel width d = 200μm, a pitch of 1.5mm, and a helical angle of 45°. During implementation, a spiral segment (5mm long) is embedded between each branch of the fractal channel. The spiral segment is connected to the straight channel through a smooth transition zone (with a gradual curvature radius). Dean vortex intensity control and Dean number calculation are as follows:

[0045] ;

[0046] The vortex intensity is controlled by adjusting the flow rate (0.1μL / min-10μL / min) and the radius of curvature (R=1mm-3mm). The vortex period is designed so that a spiral unit is connected after every 5mm of straight channel, creating a periodic disturbance (frequency 10Hz-50Hz). Through the coordinated design of fractal flow channels and curvature-induced secondary flow, the microfluidic chip achieves precise manipulation of colloidal particles, providing technical support for the industrial production of high-performance optical films.

[0047] In this embodiment, the microfluidic chip design includes a dynamic flow rate control system for precisely regulating particle movement. Specifically, it includes: a multi-stage pressure drive system design, including a core flow pump, a sheath flow pump, and feedback control; a pulsed flow field design, including a piezoelectric actuator module, waveform parameters, and effect verification design. The dynamic flow rate control design of the microfluidic chip reduces flow rate fluctuations to ±0.5% through the coordinated control of the multi-stage pressure drive system (core flow pump + sheath flow pump), ensuring that the particle migration path deviation is less than 1μm, thereby improving flow rate stability. The sheath flow wrapping effect, in which the sheath flow (flow rate 2-5 times that of the core flow) forms a fluid "jacket" that suppresses the diffusion of the core flow (diffusion width <10μm); and pressure feedback compensation, which monitors pressure fluctuations in real time (accuracy 0.1kPa) and dynamically adjusts the pump pressure to eliminate pulsation. The particle arrangement accuracy is enhanced, and the pulse flow field (frequency 1Hz-100Hz) forces the particles to form a hexagonal close-packed (hcp) structure in the flow channel through periodic shear disturbance, with a lattice constant deviation of <1% (traditional process >5%); shear resonance effect, pulse frequency matching particle relaxation time ( ), maximizing the driving force for arrangement; inertial focusing control, high-frequency pulses (>50Hz) enhance the lateral inertial lift to achieve single-layer particle arrangement. Anti-interference and robustness, the dynamic feedback system can compensate for temperature fluctuations (ΔT=±2℃) or viscosity changes (Δη=±10%) in real time to maintain flow rate stability; adaptive PID control dynamically adjusts the proportional-integral-differential coefficient (K) according to the flow rate error p =0.8, K i =0.2, K d=0.05); multi-sensor fusion integrates flow, pressure, and temperature sensors (sampling rate 1kHz) to achieve closed-loop control. A multi-stage pressure-driven system design was developed. A high-precision syringe pump (such as the Harvard Apparatus PHD Ultra) was selected as the core flow pump, with a flow range of 0.01μL / min-100μL / min, a resolution of 0.001μL, a pump pressure range of 0kPa-100kPa, and a response time of <10ms. A pneumatic micropump (such as the Fluigent MFCS-EZ) was selected as the sheath flow pump, with an adjustable flow ratio from 3:1 to 10:1, pressure fluctuations of <0.05kPa, and a flow matching error of <0.1%. The logical steps of feedback control design include system initialization, parameter setting, state zeroing; real-time data acquisition, sensor input, target value reading; error calculation, deviation quantization, error filtering; PID (proportional-integral-differential) control quantity generation, proportional term calculation, integral term accumulation, differential term extraction, and synthetic control quantity; actuator drive, output limiting, signal conversion, and pump pressure regulation; state update and iteration, historical storage, integral anti-saturation, and loop start; the key logical process is: initialization parameters → real-time data acquisition → error calculation → generation of PID control quantity → drive actuator → update state → loop. Pulsed flow field design, piezoelectric actuation module, PZT piezoelectric sheet (size 2×2mm², thickness 0.1mm) embedded in the bottom of the PDMS flow channel, voltage peak of 50Vpp, frequency range of 1Hz-1MHz, power density of 10mW / mm²; waveform parameter optimization; square wave pulse, duty cycle of 30% (excitation time 0.3T, T is period), rise / fall time <1μs; sinusoidal modulation, frequency sweep range of 10Hz-100Hz (used to match the particle resonance frequency), amplitude gradually changes to 0V-50V linear increase.

[0048] In this embodiment, the design of the microfluidic chip includes a particle arrangement control design for constructing a periodic structure, specifically including: electric field-assisted assembly, including electrode arrangement, dielectrophoretic force, and arrangement direction control design; magnetofluidic positioning design, including superparamagnetic particles, electromagnetic arrays, and dynamic switching design. Electric field-assisted assembly, through dielectrophoretic force (DEP), achieves a hexagonal close-packed (hcp) or face-centered cubic (fcc) structure of 50nm-500nm particles with a lattice constant deviation of less than 1% and a defect density of less than 10² / cm²; controls the particle arrangement direction (horizontal / vertical) through electrode patterning (such as interdigitated or ring electrodes) to achieve anisotropic optical properties (such as polarization selectivity); the electric field can penetrate the fluid medium and maintain arrangement stability under viscosity fluctuations (±20%) or temperature changes (±10°C); dielectrophoretic force calculation, dielectrophoretic force formula: , where r is the particle radius, ε mis the dielectric constant of the medium, Re[K(ω)] is the real part of the Clausius-Mossotti factor, which is a frequency-dependent parameter used to describe the difference in dielectric properties between the particle and the medium, ∇E 2 The gradient is the square of the electric field strength; the arrangement direction is controlled by parallel electrodes generating a transverse field gradient, and the particles are arranged along the electric field equipotential lines, thereby achieving horizontal arrangement; the vertical electrodes generate a longitudinal field gradient, and the particles are arranged upright (the field strength needs to be greater than 5V / μm), thereby achieving vertical arrangement; by time-sharing power supply of the multi-electrode array, a patterned structure (such as stripes / dots) is achieved, thereby achieving dynamic switching. Magnetofluidic positioning design uses magnetic field gradients to achieve three-dimensional positioning of superparamagnetic particles (such as Fe3O4@SiO2) and construct a 3D colloidal lattice (such as body-centered cubic bcc), with an interlayer spacing control accuracy of ±10nm; the electromagnetic array switches the magnetic field direction at a frequency of 10Hz-100Hz to achieve dynamic reorganization of the microstructure (response time <10ms); the magnetic field is contactless and has no thermal effect, making it suitable for the co-assembly of living cells or biomolecules. Preparation of superparamagnetic particles: Fe3O4 core (diameter 50nm) and SiO2 coating (thickness 10nm) are synthesized by co-precipitation method. The magnetization parameters and saturation magnetization intensity M s =50emu / g, coercive force H c <10e. Electromagnetic array design, miniature Helmholtz coils (1mm diameter, 0.5mm pitch), single-coil magnetic field strength 0.1T, gradient >10T / m; drive circuit: H-bridge circuit (current 0A-1A, switching frequency 100Hz), PID control magnetic flux fluctuation <1%; magnetophoretic force control, magnetophoretic force formula: , where V is the particle volume, χ is the magnetic susceptibility of the particle, μ0 is the vacuum permeability, is the gradient of the square of the magnetic field strength.

[0049] In this embodiment, after step S104, the following further steps are included: S105, performing an optical performance stability test to verify the optical property retention capability of the colloidal crystal film in an actual application environment. The specific functions include:

[0050] Functional verification ensures that the photonic bandgap position (e.g., the design value of 550nm) is within the allowable deviation (e.g., ±1nm) and meets the performance requirements of optical devices (e.g., filters, sensors); verifies whether the transmittance, reflectance, and polarization characteristics meet the standards (e.g., average transmittance in the visible light region > 90%).

[0051] Environmental adaptability assessment: testing the optical stability of the film under extreme conditions such as temperature (-40°C-85°C), humidity (5%RH-95%RH), and UV radiation (1W / m²); quantifying the band gap shift (e.g., shift <2nm after 1000 hours of damp heat aging) to evaluate material durability.

[0052] Process optimization feedback: reversely optimize microfluidic chip parameters (such as flow rate and electric field strength) through test data to improve production consistency; identify manufacturing defects (such as local structural collapse leading to increased scattering loss).

[0053] Reliability certification provides reliability data (such as MTBF > 100,000 hours) for industrial mass production, meeting industry access standards for equipment.

[0054] The design method for the optical unclonable function system of this embodiment utilizes the aforementioned method for preparing liquid colloidal crystal thin film materials and includes the following steps: S201: Preparation of a colloidal particle solution using solution-based and wet chemical synthesis combined with interface-induced assembly technology to ensure uniform nanoparticle size and controllable morphology; Optimization of reaction conditions to improve particle dispersion and stability, thereby ensuring the reliability and repeatability of the PUF system under different environmental conditions; S202: Preparation of a liquid colloidal crystal thin film using a dual-channel or multi-channel fluidic structure to optimize fluid chaos effects and promote uniform distribution of nanoparticles at the liquid-solid interface; Precise control of flow rate, pressure gradient, and flow channel structure to avoid particle agglomeration or disordered accumulation, thereby ensuring the stability and consistency of the PUF film structure; S203: Detection of the optical fingerprint of the PUF film using an optical sensor by illuminating the film with a laser or tunable light source and recording the transmitted, reflected, or scattered light signals; Extraction of optical data using Fourier transform spectroscopy or photon correlation spectroscopy to generate a unique optical code, ensuring high security and non-replicability in encryption and anti-counterfeiting applications. The design method of the optical unclonable function (PUF) system achieves high security, non-replicability, and environmentally robust anti-counterfeiting and encryption functions through the synergistic effect of multiple steps. The colloidal particle solution is prepared by solution method and wet chemical synthesis (such as Stöber method and seed growth method) to obtain nanoparticles with uniform size (diameter deviation <3%) and controllable morphology (spherical / rod-shaped / core-shell structure) to achieve particle uniformity and morphological control. The uniformity of the particles provides the basis for the periodic structure of the subsequent colloidal crystal film, and the morphological controllability gives the PUF unique scattering or resonant optical properties, enhancing the uniqueness of the code; the reaction conditions are regulated (pH = 9-11, surfactant concentration 0.1wt%-1wt%), through electrostatic repulsion or steric hindrance effects (such as PEG modification) Achieve particle monodispersion (PDI < 0.05) to optimize dispersibility and stability, avoid film defects caused by agglomeration (defect density < 10² / cm²), and ensure the stability of PUF under different temperature and humidity conditions (-40°C-85°C) and chemical environments (pH: 4-10); utilize gas-liquid or liquid-liquid interface self-assembly (such as Langmuir-Blodgett technology) to form a tightly packed monolayer (hexagonal close packing accounts for > 95%) to achieve interface-induced assembly enhancement and generate a "seed layer" with a submicron ordered structure, providing a controllable template for microfluidic film preparation.Liquid colloidal crystal film preparation, through dual-channel or multi-channel flow control structure (such as spiral flow channel, contraction-expansion unit) to induce Dean vortex (Dean number De=0.5-5), enhance the lateral migration of particles, so as to achieve the control of fluid chaos effect, and realize the disordered-ordered coordinated distribution of particles at the liquid-solid interface (long-range disorder, short-range order), forming an unpredictable microstructure "fingerprint"; through PID feedback to adjust the flow rate (0.1μL / min-10μL / min, fluctuation <0.5%) and pressure gradient (±0.1kPa), combined with fractal flow channel design (width shrinkage ratio 0.618) to achieve precise control of dynamic parameters, inhibit particle agglomeration (agglomerate size <500nm), ensure film thickness uniformity (CV value <3%), and improve the repeatability of PUF preparation (>99%); through integrated electric field (AC: 10V / 1kHz) or magnetic field (0.1T gradient field) assisted assembly, the particle arrangement direction (such as anisotropic photonic band gap) is dynamically controlled to achieve multi-physics field coupling design, and multiple physical entropy sources (electric field perturbation, flow velocity noise) are embedded in the film, making the PUF non-clonable (information entropy >10). 6 bits) surpasses traditional random number generators. Optical fingerprint detection and code generation uses tunable lasers (wavelength range 400nm-1000nm, resolution 0.1nm) or wide-spectrum LED light sources, combined with high-sensitivity CCD / CMOS arrays (pixel size 1μm) to achieve high-resolution optical sensing, capture the transmission / reflection / scattering spectral details of the film (such as photonic band gap position, polarization-dependent scattering angle), and generate multi-dimensional optical features (such as 1000-dimensional data points); by analyzing spectral frequency domain features (such as characteristic peak half-width <0.5nm), quantifying the band gap modulation depth, measuring particle motion correlation through dynamic light scattering (DLS), extracting structural fluctuation entropy to achieve spectral analysis and code extraction, converting physical randomness into digital code (such as 256-bit hash value), ensuring code uniqueness (collision probability <10 -20 ); combined with cross-certification of transmission spectroscopy (bandgap position), dark-field scattering (nanostructure), and fluorescent labeling (quantum dot coding), the PUF's unpredictable response (such as a bandgap shift of ±1nm) is triggered by temperature / electric field perturbations to achieve anti-attack and anti-counterfeiting capabilities, and to resist physical copying (imitation success rate <0.01%), machine learning modeling attacks (prediction error >30%), and side-channel analysis. Through full-chain innovation of colloidal particle synthesis-microfluidic assembly-optical code extraction, the optical PUF system combines physical unclonability, high entropy security, and environmental robustness, providing an industrially feasible solution for the next generation of anti-counterfeiting and encryption technologies. Its core breakthrough lies in combining the intrinsic randomness of nanomaterials with the precise manipulation of microfluidics to achieve "controllable unpredictability", which has disruptive potential in the fields of information security and material traceability.

[0055] The application of the optical-physical unclonable function system of this embodiment adopts the design method of the optical-physical unclonable function system described above, combines the optical-physical unclonable function system with an optical fingerprint for security authentication and anti-counterfeiting, and is applied to anti-counterfeiting labels, intelligent recognition systems, or high-security encryption modules.

[0056] Example 1:

[0057] The liquid colloidal crystal thin film material is obtained according to the above-mentioned preparation method of the liquid colloidal crystal thin film material. The prepared liquid colloidal crystal thin film material has the following technical indicators:

[0058] Particle size: 50nm-500nm, detection: SEM / TEM;

[0059] Transmittance: 85%-95%, Detection: UV-Vis spectroscopy;

[0060] Haze: <5%, test: ASTM D1003;

[0061] Thickness: 10μm-100μm, detection: profilometer;

[0062] Tensile elongation: 10%-30%, detection: tensile test;

[0063] Tensile strength: 5MPa-20MPa, detection: tensile test;

[0064] Glass transition temperature: 60℃-110℃, detection: DSC test;

[0065] Birefringence: 0.01-0.05, detection: polarizing microscope.

[0066] Example 2:

[0067] The design method of optical physics unclonable function system includes:

[0068] S201. Preparation of colloidal particles.

[0069] The goal of this step is to synthesize high-quality nanoparticles (such as polystyrene (PS) or silicon dioxide (SiO2)) and ensure particle uniformity and stability. The nanoparticle diameter should be in the range of 50nm-500nm, with a standard deviation of less than 5% to ensure the periodic structure and stable optical properties of the final colloidal crystal film.

[0070] To prepare the reagents, first prepare a MAA / SDS mixed solution by adding 3.75 μL of methacrylic acid (MAA) to 5 mL of a 0.025 wt% sodium dodecyl sulfate (SDS) aqueous solution. Mix thoroughly and set aside. Also, prepare a 0.1 g / mL KPS solution by dissolving 1 g of potassium persulfate (KPS) in 10 mL of ultrapure water. Finally, prepare 1 mL of styrene monomer.

[0071] Synthesis of polystyrene (PS) nanospheres.

[0072] PS nanospheres were synthesized using a microemulsion polymerization method. The lipid phase in the reaction system consisted of styrene monomer, and the aqueous phase consisted of a MAA / SDS mixed solution. This experiment employed a microfluidic reaction system, strictly controlling the reaction parameters to ensure uniform nanosphere size.

[0073] Flow rate ratio (lipid phase:water phase): 1:10;

[0074] Total flow rate: 10 mL / min;

[0075] Target product amount: 1mL;

[0076] Pre-waste (waste liquid in the early stage of reaction): 0.6mL;

[0077] Heating temperature: 60℃;

[0078] Stirring rate: 300 rpm;

[0079] Reaction time: 30min-60min.

[0080] Under these conditions, PS nanospheres gradually nucleated and grew in the aqueous phase and eventually formed a stable nanoparticle suspension.

[0081] Potassium persulfate (KPS) treatment of PS nanospheres.

[0082] To further enhance the surface activity of PS nanospheres and strengthen their dispersion stability in a microfluidic environment, the nanospheres' surface needs to be oxidized. This step uses KPS solution to carboxylate the PS nanospheres' surface, increasing their hydrophilicity.

[0083] Flow rate ratio (PS nanosphere aqueous phase: KPS lipid phase): 1:10;

[0084] Total flow rate: 10 mL / min;

[0085] Target product amount: 1.5mL;

[0086] Fore waste: 0.6mL;

[0087] Heating temperature: 80℃;

[0088] Stirring rate: 400 rpm;

[0089] Reaction time: 20min-40min.

[0090] After KPS treatment, carboxyl groups are introduced on the surface of PS nanospheres, which improves their dispersibility in the aqueous phase and enables them to maintain good fluidity and stability in microfluidic channels.

[0091] S202. Preparation of liquid colloidal crystal thin film.

[0092] S2021. Inject the colloidal particle solution into the microfluidic chip.

[0093] The purpose of this step is to introduce the prepared colloidal particle solution into the microchannels of the microfluidic chip to ensure uniform particle distribution and avoid agglomeration. The microfluidic chip contains multiple microchannels (channel width 20μm-100μm) designed for laminar flow control to achieve precise control of particle arrangement.

[0094] Injection flow rate: 0.1mL / min-1.0mL / min;

[0095] Chip channel size: 20μm-100μm;

[0096] Particle concentration: 0.5wt%-5wt%;

[0097] Solution temperature: 25℃-40℃.

[0098] When to stop injection: When the particles in the channel are arranged to form a stable periodic structure and the transmitted light scattering characteristics tend to be stable (monitored by optical microscope).

[0099] Through precise flow rate control of the microfluidic device, the particles are evenly distributed in the microchannel to avoid aggregation of particles or the formation of particle-free areas.

[0100] S2022. Microfluidics controls particle arrangement.

[0101] In this step, the periodic arrangement of nanoparticles is achieved by precisely adjusting the flow rate and pressure gradient using hydrodynamic effects. The microfluidic system utilizes a laminar flow pattern combined with a passive vortex structure to ensure that the particles self-assemble into a periodic photonic lattice within the channel, improving the optical uniformity of the film.

[0102] Particle arrangement: hexagonal close packing (HCP) or cubic close packing (FCC);

[0103] Flow rate adjustment range: 0.1mL / min-5.0mL / min;

[0104] Pressure gradient: 1Pa / m-10Pa / m.

[0105] Fluid Mode:

[0106] Under low Reynolds number conditions: laminar flow;

[0107] Appropriate introduction of nonlinear flow channels (such as spiral flow channels and cross flow channels) can increase the orderliness of particle arrangement.

[0108] Particle deposition rate: 10μm / min-50μm / min;

[0109] Stable particle arrangement time: 30s-90s.

[0110] After precise microfluidic control, the colloidal particles can form a uniform arrangement on the microscopic scale and ensure the consistency of the optical properties of the film.

[0111] S203, film curing and stability test.

[0112] The goal of this step is to ensure the stability of the film structure through curing treatment and perform optical performance tests to verify its stability under different environmental conditions.

[0113] S2031. Solidify the system.

[0114] Depending on application requirements, you can choose UV curing or thermal curing:

[0115] UV curing (applicable to photosensitive colloid systems)

[0116] Light source: 365nm UV lamp;

[0117] Irradiation time: 5min-10min;

[0118] Light intensity: 100mW / cm²-500mW / cm²;

[0119] Heat curing (applicable to thermosetting materials);

[0120] Temperature range: 60℃-90℃;

[0121] Curing time: 30min-60min;

[0122] Target viscosity change rate: <5%.

[0123] S2032, film performance test.

[0124] After the film is cured, the following optical and physical properties tests are required:

[0125] Light transmittance test:

[0126] Equipment: UV-Vis spectrophotometer;

[0127] Wavelength range: 200nm-800nm;

[0128] Target light transmittance: 85%-95%.

[0129] Haze test:

[0130] Equipment: ASTM D1003 standard haze meter;

[0131] Target haze: <5%;

[0132] Refractive index measurement:

[0133] Equipment: Ellipsometer;

[0134] Target refractive index: 1.4-1.6.

[0135] Tensile properties test:

[0136] Equipment: Electronic tensile testing machine;

[0137] Target tensile strength: 5MPa-20MPa;

[0138] Tensile elongation: 10%-30%.

[0139] Environmental stability test:

[0140] High temperature and humidity test (60℃, 85%RH, 72h);

[0141] Solvent resistance test (isopropyl alcohol, ethanol, 24h).

[0142] Example 3:

[0143] Based on the application of liquid colloidal crystal thin film materials, a design method for an optical physical unclonable function (PUF) system is provided, which includes the following steps:

[0144] S201. The purpose of this step is to achieve controllable synthesis of anisotropic nanoparticles by combining solution method and wet chemical synthesis, using liquid-nano-liquid interface induced growth technology, to ensure the uniqueness of the optical "fingerprint" in the PUF system.

[0145] Process parameters:

[0146] Nanoparticle Type:

[0147] Materials: silicon dioxide (SiO2), metal nanoparticles (Ag, Au), indium tin oxide (ITO);

[0148] Particle size: 50nm-500nm (characterized by TEM);

[0149] Morphology: spherical, rod-like, cubic (controlled by interface-induced assembly).

[0150] Solution preparation:

[0151] Adopting liquid-nano-liquid interface induction technology;

[0152] Aqueous phase: nanoparticle suspension (concentration 0.1wt%-5wt%);

[0153] Oil phase: hexane or toluene (concentration 5vol%-15vol%);

[0154] Surfactant: SDS (0.01wt%-0.1wt%) or Tween-20 (0.05wt%-0.2wt%).

[0155] Synthetic conditions:

[0156] Temperature: 25℃-60℃;

[0157] Stirring speed: 200rpm-800rpm;

[0158] Reaction time: 10min-120min.

[0159] Morphology optimization:

[0160] By adjusting the oil-water ratio (1:1-1:10);

[0161] Optimize particle stability by plasma treatment or functional group modification.

[0162] Experimental process:

[0163] In the microemulsion system, the distribution of nanoparticles is controlled to form uniform optical properties.

[0164] The interfacial energy difference is used to regulate the morphology and orientation of the particles, avoid particle agglomeration, and improve the uniqueness of PUF.

[0165] The morphology and interface characteristics of the nanoparticles were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) to ensure uniform particle distribution.

[0166] S202. Preparation of liquid colloidal crystal thin film.

[0167] S2021. The purpose of this step is to use the microfluidic chip to accurately control the arrangement structure of anisotropic nanoparticles to ensure the uniformity and high stability of the PUF film.

[0168] Process parameters:

[0169] Microfluidic chip structure:

[0170] Channel width: 20μm-100μm;

[0171] Channel flow rate control: 0.1mL / min-5mL / min;

[0172] Channel entrance angle: 30°-90° (optimized particle arrangement).

[0173] Fluid Chaos Effect:

[0174] Adopt laminar flow + passive mixing strategy (such as spiral channel);

[0175] Fluid type: water phase + oil phase;

[0176] Fluid flow rate control: 0.1mL / min-2.0mL / min.

[0177] Drive mode:

[0178] External field coupling (electric field, magnetic field, acoustic wave);

[0179] Active disturbances (oscillatory flow, pulsed flow).

[0180] Experimental process:

[0181] Optimize the ratio of water phase, oil phase and surfactant to enhance the orderliness of nanoparticle arrangement.

[0182] Microfluidic chips are used to precisely control the fluid path and flow rate to ensure that the nanoparticles form a highly uniform self-assembled structure.

[0183] Through the fluid chaos effect, the self-assembly of nanoparticles is driven to improve the functional stability of the PUF film.

[0184] S2022. The goal of this step is to ensure that the nanoparticles are evenly distributed in the PUF film, avoid particle agglomeration or particle-free areas, and ensure that the PUF system has stable physical randomness.

[0185] Process parameters:

[0186] Flow channel size: 20μm-100μm;

[0187] Flow rate control: 0.1mL / min-2.0mL / min;

[0188] Temperature control: 25℃-60℃;

[0189] Pressure gradient: 1Pa / m-10Pa / m.

[0190] Fluid Mode:

[0191] Low flow rate: laminar flow (for controlled uniform distribution);

[0192] High flow rate: turbulence (increases particle randomness).

[0193] Experimental process:

[0194] Numerical simulation and dual-channel mixing experiments were used to systematically analyze the effects of flow channel size, incident angle, and flow velocity on nanoparticle mixing.

[0195] Combined with fluid temperature optimization and pump pressure control, the doping mechanism of nanoparticles is analyzed.

[0196] By surfactant modification or particle surface modification, the wettability of the liquid-solid interface is optimized, the dispersion stability of nanoparticles is improved, and particle agglomeration is prevented.

[0197] A density matching strategy is adopted to ensure that the density of nanoparticles and liquid substrate is close to each other and reduce particle segregation.

[0198] S203: The goal of this step is to utilize the unique optical properties of the PUF film based on optical detection technology to generate a unique "fingerprint" for use in high-security encryption, anti-counterfeiting authentication, and identity verification. Because the optical properties of the PUF film are derived from the arrangement of nanoparticles, scattering characteristics, and photonic bandgap effects, a high-precision optical detection system is required to extract this unique information and convert it into optical "fingerprint" data for secure verification.

[0199] Process parameters;

[0200] Optical detection method:

[0201] Transmitted light detection (detecting the photonic band gap and transmittance of PUF films);

[0202] Reflected light detection (analyzing the scattering and interference effects of the film on incident light);

[0203] Fluorescence detection (for PUF films doped with fluorescent nanoparticles);

[0204] Light source type:

[0205] Laser wavelength range: 405nm-850nm (visible light and near-infrared light);

[0206] LED light source: 450nm-780nm (for adjustable wavelength scanning).

[0207] Optical sensor:

[0208] CCD camera (for optical image recognition);

[0209] Photodetector (for spectral data acquisition);

[0210] Incident angle: 0°-60° (multi-angle spectrum detection improves uniqueness);

[0211] Fourier transform spectroscopy (FTIR): used to detect the characteristic absorption spectrum of PUF films.

[0212] Experimental process:

[0213] PUF film optical signal acquisition;

[0214] Laser (405nm-850nm) is used to irradiate the surface of the PUF film. The optical sensor collects the reflected light, transmitted light and scattered light signals and records the spectral characteristics.

[0215] For PUF films doped with fluorescent nanoparticles, a fluorescence excitation light source (450nm-600nm) can be used to analyze the fluorescence emission spectrum of the film to further enhance the uniqueness of the PUF.

[0216] Optical "fingerprint" data extraction.

[0217] The spectral data were analyzed by Fourier transform infrared spectroscopy (FTIR) and photon correlation spectroscopy (PCS), and a characteristic spectrum database of PUF films was established.

[0218] Multi-angle spectral scanning (0°-60°) is used to extract optical responses at different incident angles to improve the uniqueness of optical "fingerprint" data.

[0219] Data digitization and identity authentication.

[0220] Optical data is digitized using Fourier transform algorithm (FFT) or principal component analysis (PCA) and converted into a unique digital identity code.

[0221] The optical fingerprint data is encrypted using a hash algorithm (SHA-256) to ensure its security during data storage and transmission.

[0222] Establish a PUF database and match it with existing optical "fingerprint" information to achieve identity authentication.

[0223] Safety Applications:

[0224] In anti-counterfeiting technology, PUF film can be used as an unreplicable optical label and applied in scenarios such as brand anti-counterfeiting and high-end electronic product identification.

[0225] In information security, optical "fingerprints" can be used for identity authentication, encryption systems, and data storage protection to ensure the unforgeability and uniqueness of information.

[0226] The optical detection technology in this step ensures the high security, uniqueness and non-cloning of the PUF system, providing reliable technical support for future anti-counterfeiting authentication, information security and intelligent encryption.

[0227] Compared with the existing technology, it has the following technical effects:

[0228] 1. The stability of optical properties is significantly improved.

[0229] 2. Microfluidic technology is used to control particle arrangement and optimize the colloidal crystal structure, thereby improving the photonic band gap stability by more than 30%.

[0230] 3. The optical stability of the film under different temperature and humidity environments is enhanced, reducing the impact of environmental factors on optical "fingerprints".

[0231] 4. High structural control precision, achieving precise and controllable optical "fingerprint" generation.

[0232] 5. By optimizing the microfluidic channel design, the nanoparticles are arranged in a hexagonal close packing (HCP) or cubic close packing (FCC) manner, making the film structure more ordered and the optical consistency improved by more than 20%.

[0233] 6. The detection accuracy of the optical sensor is improved, which significantly enhances the uniqueness and randomness of the optical "fingerprint" of the PUF film.

[0234] 7. Optimize production process to achieve large-scale preparation.

[0235] 8. Use low-cost microfluidic technology to replace traditional deposition methods, increase production efficiency by 50%, and reduce the cost of thin films per unit area by at least 40%.

[0236] 9. Microfluidic technology is suitable for continuous production and can meet the needs of large-scale industrialization.

[0237] 10. Enhance the security of the PUF system and improve the anti-counterfeiting effect.

[0238] 11. By combining optical fingerprints with randomly distributed nanoparticles, the optical security of the PUF system is increased by more than 3 times.

[0239] 12. Use technologies such as Fourier transform spectroscopy (FTIR) and photon correlation spectroscopy (PCS) to improve the anti-cracking capabilities of the encryption system.

[0240] 13. Optimize the environmental adaptability of the film.

[0241] 14. Through interface modification and particle optimization, the heat resistance of the film is improved by 20% or more, and the moisture resistance is improved by 35% or more.

[0242] 15. Applicable to extreme environments (such as high temperature, humidity or strong light exposure) to ensure the long-term stability of PUF film.

[0243] In summary, the present invention uses microfluidic technology to precisely control the structure of colloidal crystal films, realizing an optical PUF system with stable optical performance, high production efficiency, and strong safety, which has broad application prospects.

[0244] Noun introduction:

[0245] PUF (Physical Unclonable Function): A technology that generates a unique identifier based on the physical differences of a chip.

[0246] PUF films (Physically Unclonable Function Films) are functional films that generate unique identifiers based on the inherent randomness of the material. They are widely used in anti-counterfeiting, encryption, and hardware security. PUF films utilize the uncontrollable random distribution of microstructures or components (such as nanoparticle arrangement, surface morphology, and defect distribution) naturally formed during film preparation. Through physical measurements (such as optical, electrical, and mechanical properties), unique features are extracted and converted into digital keys or identity identifiers.

[0247] Colloidal Crystal Film: Colloidal crystal films are thin films with periodic structures formed by the self-assembly of nanoparticles (such as polystyrene and silica). The colloidal particles are processed through solution to form a long-range ordered crystalline structure that exhibits unique optical properties, such as the photonic bandgap effect.

[0248] Photonic Band Gap (PBG): A PBG is an optical property created by periodically arranged microstructures in certain materials, such as colloidal crystals, that prevents light within a specific frequency range from propagating. PBG materials are commonly used in optical sensing, anti-counterfeiting labels, and encryption systems, effectively controlling light propagation and enhancing system security.

[0249] Microfluidics: Microfluidics is the technology used to manipulate and regulate matter by precisely controlling the flow of fluids at microscopic scales. This technology is commonly used for the self-assembly and precise arrangement of nanoparticles and is widely used in fields such as biomedicine, chemical analysis, and materials science. In this invention, microfluidics is used to precisely control the arrangement of colloidal particles, ensuring the structural accuracy of colloidal crystal films.

[0250] Self-assembly: Self-assembly is a process in which molecules or nanoparticles spontaneously form ordered structures by leveraging intrinsic interactions of matter, such as van der Waals forces, electrostatic forces, and hydrogen bonds. Traditional methods for preparing colloidal crystal thin films rely on self-assembly, but their structural precision and stability are difficult to control.

[0251] Optical Anti-Counterfeiting: Optical anti-counterfeiting technology utilizes specialized optical materials and structures to ensure product authenticity through unique optical properties that cannot be replicated. Optical anti-counterfeiting labels often utilize photonic bandgap materials and optical films, and are verified through optical recognition technology.

[0252] Nanoparticles: Nanoparticles are particles with a diameter between 1 and 100 nanometers. They typically have a large surface area and unique physical and chemical properties. As the base material for colloidal crystal thin films, they determine the film's optical properties and structural stability.

[0253] Optical Fingerprint: An optical fingerprint is identity authentication information generated based on the unique properties of optical materials. Each optical fingerprint is unique. By measuring the optical properties of a film (such as reflectance spectra and diffraction patterns), a fingerprint code can be generated for encryption and identity verification.

[0254] Optical Sensor: An optical sensor is used to detect and measure properties of light, such as intensity and wavelength, and is typically used to obtain response information from optical films or materials. In this invention, the optical sensor is used to detect the optical properties of colloidal crystal films and generate corresponding "fingerprint" information.

[0255] Matters not covered by the present invention are known technologies.

[0256] 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.

[0257] 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.

[0258] 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 preparing a liquid colloidal crystal thin film material, characterized in that: The following steps are involved: S101, preparing a monodisperse colloidal particle solution; S102. Use dual-channel or multi-channel flow control structures to optimize fluid chaos effects and promote uniform distribution of nanoparticles at the liquid-solid interface; avoid particle agglomeration or disordered accumulation by precisely controlling flow rate, pressure gradient, and flow channel structure; The dual-channel or multi-channel fluidic structure in S102 uses a microfluidic chip. Based on the flow rate and fluid dynamics effect of the microfluidic chip, the multiple micro channels of the microfluidic chip are adjusted to assemble a colloidal crystal film with a periodic structure, ensuring the precise arrangement of nanoparticles at the microscale. The design of the microfluidic chip includes the design of fractal flow channel structures for achieving uniform flow velocity distribution, specifically including: tree-like fractal network structure design, including branching level, width contraction ratio and depth gradient design; curvature-induced secondary flow design, including spiral channel units, Dean vortex intensity and vortex period design; The design of the microfluidic chip includes dynamic flow rate control for precise regulation of particle motion, specifically including: multi-stage pressure drive system design, including core flow pump, sheath flow pump, and feedback control design; pulse flow field design, including piezoelectric actuation module, waveform parameters, and effect verification design; S103, injecting colloidal particle solution; S104: After the film is formed, a curing process is performed to ensure that the film structure is stable, thereby obtaining a colloidal crystal film with stable optical properties.

2. The method for preparing a liquid colloidal crystal thin film material according to claim 1, wherein: In step S101, a colloidal particle solution is prepared using nanoparticles, where the nanoparticles are polystyrene nanoparticles or silicon dioxide nanoparticles; Solution and wet chemical synthesis, combined with interface-induced assembly technology, are used to make nanoparticles with uniform size and controllable morphology; The reaction conditions were optimized to improve the dispersion and stability of the nanoparticles.

3. The method for preparing the liquid colloidal crystal thin film material according to claim 2, characterized in that: Step S101 of preparing a monodisperse colloidal particle solution specifically includes: Nanoparticle pretreatment, Surface functionalization to enhance stability, Solution rheology optimization, Sterilize and store until ready for use.

4. The method for preparing a liquid colloidal crystal thin film material according to claim 1, wherein: The design of microfluidic chips includes the controlled design of particle arrangement used to construct periodic structures, specifically including: Electric field-assisted assembly, including electrode placement, dielectrophoretic force, and alignment direction control design; Magnetofluidic positioning design, including superparamagnetic particles, electromagnetic arrays, and dynamic switching designs.

5. The method for preparing a liquid colloidal crystal thin film material according to any one of claims 1 to 4, characterized in that: After step S104, the method further includes: S105, performing an optical performance stability test.

6. A method for designing an optical unclonable function system, applying the method for preparing a liquid colloidal crystal thin film material according to any one of claims 1 to 5, characterized in that: The following steps are involved: S201. Preparation of colloidal particle solutions using solution and wet chemical synthesis, combined with interface-induced assembly technology, to achieve uniform nanoparticle size and controllable morphology. Optimization of reaction conditions to improve particle dispersibility and stability ensures the reliability and repeatability of the PUF system under different environmental conditions. S202. Liquid colloidal crystal film preparation, using dual-channel or multi-channel flow control structures to optimize fluid chaos effects and promote uniform distribution of nanoparticles at the liquid-solid interface. By precisely controlling flow rate, pressure gradient, and flow channel structure, particle agglomeration or disordered accumulation is avoided, ensuring the stability and consistency of the PUF film structure. S203. Detect the optical fingerprint of the PUF film through an optical sensor, illuminate the film with a laser or a tunable light source, and record the transmitted, reflected, or scattered light signals; extract the optical data using Fourier transform spectroscopy or photon correlation spectroscopy, and generate a unique optical code to ensure its high security and non-replicability in encryption and anti-counterfeiting applications.

7. An application of an optical physics unclonable function system, characterized in that: The design method of the optical physical unclonable function system described in claim 6 is adopted, combined with the optical physical unclonable function system, and optical fingerprints are used for security authentication and anti-counterfeiting, and are applied to anti-counterfeiting labels, intelligent recognition systems or high-security encryption modules.