Preparation method and application of liquid colloidal crystal film material

Abstract

The 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 film material comprises the following steps: preparing a monodispersed colloidal particle solution; a dual-channel or multi-channel flow control structure is adopted, so that the chaos effect of fluid is optimized, and uniform distribution of nano-particles on a liquid-solid interface is promoted; by accurately controlling the flow speed, the pressure gradient and the flow channel structure, particle aggregation or disordered accumulation is avoided; injecting a colloidal particle solution; after the film is formed, the film structure is ensured to be stable through curing treatment, and the colloidal crystal film with stable optical characteristics is obtained. Through fusion of fluid mechanics, colloidal chemistry and interface engineering technologies and combination of a micro-fluidic technology and a colloidal crystal thin film technology, the technical bottlenecks of a traditional optical thin film material in structural precision, environmental stability and large-scale production are overcome, and a solution is provided for high-safety photoelectric 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 preparation method of a liquid colloidal crystal thin film material. In addition, the present invention also relates to a design method of an optical physical unclonable function system applying the preparation method of the liquid colloidal crystal thin film material. In addition, the present invention also relates to an application of the optical physical unclonable function system. Background Art

[0002] In recent years, optical thin film materials have important value in optoelectronic encryption, anti-counterfeiting and high-security applications, but their practical applications have long been limited by the inherent defects of traditional preparation technologies. Existing technologies mostly adopt processes such as self-assembly method, spin coating method or vertical deposition method. These methods have significant bottlenecks in terms of structural regulation accuracy, environmental stability and large-scale production, specifically manifested as: 1. Coarse structural regulation leads to unstable optical performance The photonic band gap characteristics of existing thin film materials are easily affected by environmental fluctuations such as temperature and humidity. For example, for colloidal crystal thin films based on the self-assembly method, when the temperature changes or the humidity fluctuates, the lattice parameter shifts due to the change of the interaction force between particles, and the photonic band gap wavelength shifts greatly. Such instability severely limits the application reliability of the material in scenarios that need to be exposed to complex environments for a long time.

[0003] 2. Insufficient structural regulation accuracy Traditional self-assembly technology relies on natural crystallization during the evaporation of the solution. Its particle arrangement is randomly affected by factors such as the solvent evaporation rate and the substrate surface energy, and it is difficult to achieve a long-range ordered periodic structure. In addition, problems such as wide particle size distribution and weak interface bonding result in poor consistency of the optical response of the thin film, and cannot meet the strict structural uniformity requirements for high-precision optical "fingerprint" encryption.

[0004] 3. Limited large-scale production and high cost 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). The production time for a single batch is long and the yield is low. Summary of the Invention

[0005] The present invention provides a preparation method of a liquid colloidal crystal thin film material, a design method of an optical physical unclonable function system and an application. It proposes a preparation method of a liquid colloidal crystal thin film based on microfluidic technology. Through the collaborative optimization of multi-channel flow control structure design, precise regulation of fluid dynamics and interface curing, it breaks through the bottlenecks of disordered structure, environmental sensitivity and low production efficiency in traditional technologies, and provides a reliable solution for high-security optical encryption and anti-counterfeiting applications.

[0006] 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 chaotic effect and promote the uniform distribution of nanoparticles on the liquid-solid interface; by precisely controlling the flow rate, pressure gradient and channel structure, avoiding particle aggregation or disordered accumulation; S103, injecting the colloidal particle solution; S104, after the thin film is formed, ensuring the stability of the thin film structure through a curing process to obtain a colloidal crystal thin film with stable optical properties.

[0007] Further, in step S101, nanoparticles are used to prepare the colloidal particle solution, and the nanoparticles are polystyrene nanoparticles or silica nanoparticles; the solution method and wet chemical synthesis are adopted, combined with the interface-induced assembly technology, so that the sizes of the nanoparticles are uniform and have controllable morphologies; by optimizing the reaction conditions, the dispersibility and stability of the nanoparticles are improved.

[0008] Further, the preparation of the monodisperse colloidal particle solution in step S101 specifically includes: nanoparticle pretreatment, surface functionalization to enhance stability, solution rheology optimization, sterilization and storage for standby.

[0009] Further, the dual-channel or multi-channel flow control structure in step S102 adopts a microfluidic chip. According to the flow rate and hydrodynamic effect of the microfluidic chip, multiple micro-channels of the microfluidic chip are adjusted to assemble a colloidal crystal thin film with a periodic structure, ensuring the precise arrangement of nanoparticles at the microscale.

[0010] Further, the design of the microfluidic chip includes a fractal channel structure design for achieving a uniform flow rate distribution, specifically including: dendritic fractal network construction design, including branch order, width contraction ratio, and depth gradient design; curvature-induced secondary flow design, including spiral channel unit, Dean vortex intensity, and vortex period design.

[0011] Further, the design of the microfluidic chip includes a dynamic flow rate control design for precisely regulating particle movement, specifically including: multi-stage pressure-driven system design, including a core flow pump, a sheath flow pump, and feedback control design; pulsed flow field design, including a piezoelectric actuation module, waveform parameters, and effect verification design.

[0012] Further, 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 array, and dynamic switching design.

[0013] Further, after step S104, it further includes: S105, performing an optical performance stability test.

[0014] According to another aspect of the present invention, there is also provided a design method for an optical physical unclonable function system, which applies the above-mentioned preparation method of the liquid colloidal crystal thin film material, and includes the following steps: S201, preparation of colloidal particle solution, using solution method and wet chemical synthesis, combined with interface-induced assembly technology, so that the sizes of the nanoparticles are uniform and have controllable morphology; by optimizing the reaction conditions, improving the dispersibility and stability of the particles, and ensuring the reliability and repeatability of the PUF system under different environmental conditions; S202, preparation of liquid colloidal crystal thin film, using a two-channel or multi-channel microfluidic structure to optimize the fluid chaotic effect and promote the uniform distribution of nanoparticles on the liquid-solid interface; by precisely controlling the flow rate, pressure gradient and channel structure, avoiding particle agglomeration or disordered accumulation, and ensuring the stability and consistency of the PUF thin film structure; S203, detecting the optical fingerprint of the PUF thin film through an optical sensor, irradiating the thin film with a laser or a tunable light source, and recording the transmitted, reflected or scattered light signals; using Fourier transform spectroscopy analysis or photon correlation spectroscopy method to extract optical data and generate a unique optical code to ensure its high security and non-replicability in encryption and anti-counterfeiting applications.

[0015] According to another aspect of the present invention, there is also provided an application of an optical physical unclonable function system, which adopts the above-mentioned design method of the optical physical unclonable function system, combines the optical physical unclonable function system, uses the optical fingerprint for security authentication and anti-counterfeiting, and is applied to anti-counterfeiting labels, intelligent identification systems or high-security encryption modules.

[0016] The present invention has the following beneficial effects: 1. Monodisperse colloidal particle solution, through surface functionalization and solution rheology optimization, the surface charge and polymer chains inhibit the agglomeration caused by van der Waals forces, ensuring the monodispersity of the colloidal particles. The monodisperse particles spontaneously form an ordered arrangement in the flow field through entropy maximization, laying a foundation for subsequent ordered assembly.

[0017] 2. The two-channel of the multi-channel microfluidic structure and its microfluidic design are combined with the chaotic mixing effect. By fractal design of the channel, the shear force fluctuation is reduced, the particle migration rate is precisely adjusted, the particles are uniformly distributed on the liquid-solid interface, and local agglomeration is avoided.

[0018] 3. Cross-linked networks are formed by photocuring or thermal curing, which improves the Young's modulus of the thin film and has a small band gap shift after wet heat aging; gradient heating eliminates thermal stress and avoids crack generation.

[0019] 4. The microfluidic chaotic effect introduces process randomness, which can generate unique optical "fingerprints" with a low imitation similarity; the cross-linked structure can withstand extreme wet heat and mechanical bending, and has a high performance retention rate.

[0020] 5. By integrating fluid mechanics, colloid chemistry, and interface engineering technologies, and combining microfluidics technology with 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 a new generation of high-security optoelectronic encryption, anti-counterfeiting technologies, and flexible optoelectronic devices.

[0021] 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. Detailed implementation manners

[0022] The following will detail 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.

[0023] 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, adopting a dual-channel or multi-channel flow control structure to optimize the fluid chaotic effect and promote the uniform distribution of nanoparticles on the liquid-solid interface; by precisely controlling the flow rate, pressure gradient and channel structure, avoiding particle aggregation or disordered accumulation; S103, injecting the colloidal particle solution; S104, after the thin film is formed, ensuring the stability of the thin film structure through curing treatment to obtain a colloidal crystal thin film with stable optical properties. The preparation method of the liquid colloidal crystal thin film material of the present invention, through the synergistic effect of multiple steps, based on the principles of hydrodynamics, interface regulation and structure stabilization, as well as the combination of microfluidic technology and colloidal crystal thin film technology, systematically solves the technical bottlenecks of traditional optical thin film materials in optoelectronic encryption and anti-counterfeiting applications; the monodisperse colloidal particle solution, through surface functionalization (such as sulfonation or PEG modification) and solution rheology optimization, the surface charge and polymer chains inhibit the aggregation caused by van der Waals forces, ensuring the monodispersity of colloidal particles. The monodisperse particles spontaneously form an ordered arrangement through entropy maximization in the flow field, laying a foundation for subsequent ordered assembly. The dual-channel / multi-channel flow control design of the multi-channel flow control structure combines the chaotic mixing effect (Dean vortex, secondary flow), reduces the shear force fluctuation through the fractal design of the channel (such as a four-level dendritic branch), precisely adjusts the particle migration rate, and realizes the uniform distribution of particles on the liquid-solid interface, avoiding local aggregation; the spiral channel unit induces the Dean vortex, breaks the laminar boundary layer, and further improves the particle distribution uniformity. The injection of the colloidal solution and the formation of the thin film, the continuous sampling of the microfluidic chip combined with the regulation of the sheath flow ratio, the sheath flow wraps the core flow, compresses the particle diffusion region, forms a monolayer close arrangement, realizes the uniform thickness and large-area continuous preparation of the thin film; a pulsed flow field is generated by a piezoelectric actuator to dynamically adjust the particle deposition rate. Curing treatment, using photocuring or thermal curing to form a cross-linked network, improving the Young's modulus of the thin film, and having a small bandgap shift after wet and heat aging; gradient heating eliminates thermal stress and avoids crack generation. Based on the combination of monodisperse particles and ordered arrangement, the full width at half maximum (FWHM) of the photonic bandgap is reduced, the wavelength shift of the photonic bandgap is small, and the stability is high; the introduction of the microfluidic chaotic effect into the process randomness can generate unique optical "fingerprints" with a low imitation similarity; the cross-linked structure can withstand extreme wet heat and mechanical bending, and has a high performance retention rate; the microfluidic chip supports parallel multi-channel (such as 16 channels) production, with high efficiency and low cost. Through the integration of hydrodynamics, colloid chemistry, and interface engineering technologies, as well as the combination of microfluidic 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 are overcome, providing solutions for a new generation of high-security optoelectronic encryption, anti-counterfeiting technologies, and flexible optoelectronic devices.

[0024] In this embodiment, in step S101, preparing a monodisperse colloidal particle solution specifically includes: Reagent preparation: 3.75 μL of methacrylic acid (MAA) was added to 5 mL of 0.025 wt% sodium dodecyl sulfate (SDS) aqueous solution and mixed evenly to obtain the MAA / SDS mixed solution; 1 g of potassium persulfate (KPS) was dissolved in 10 mL of ultrapure water to prepare a 0.1 g / mL KPS solution; 1 mL of styrene was set aside.

[0025] Fluidiclab intelligent nanoparticle synthesizer NP-S2 instrument parameter settings: (1) Synthesis of PS nanospheres: 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, and the MAA / SDS mixed solution as the aqueous phase.

[0026] (2) KPS treatment of PS nanospheres: Flow rate ratio: 1:10; total flow rate: 10 mL / min; product: 1.5 mL; pre-waste: 0.6 mL; heating: 80 °C; the product of the first step, PS nanospheres, as the aqueous phase, and 0.1 g / mL KPS solution as the lipid phase.

[0027] The chip used: Fluidiclab MTGL-FL-001 metallic glass chip.

[0028] In this embodiment, in step S101, colloidal particle solutions are prepared using nanoparticles, which are polystyrene nanoparticles or silica nanoparticles; solution methods and wet chemical synthesis are combined with an interface-induced assembly technique to make the sizes of the nanoparticles uniform and have controllable morphologies; by optimizing the reaction conditions, the dispersibility and stability of the nanoparticles are improved. The purpose of preparing the monodisperse colloidal particle solutions in step S101 is to provide highly uniform and stable colloidal units for the subsequent microfluidic assembly process, and through the coordinated regulation of materials chemistry and interface engineering, systematically solve technical bottlenecks such as particle agglomeration, uneven sizes, and poor stability in traditional processes. The uniformization of particle size and morphology is achieved by precisely controlling the particle size (such as 200 ± 5 nm for polystyrene and 300 ± 10 nm for silica) and morphology (sphericity > 99%) of the nanoparticles through solution methods (such as emulsion polymerization) and wet chemical synthesis (such as sol-gel method, Stöber method) to ensure monodispersity (PDI < 0.05); by controlling the monomer concentration, reaction temperature, and stirring rate, secondary nucleation is inhibited to achieve the growth of monodisperse particles; microemulsion droplets serve as nanoreactors (diameter 50 nm - 200 nm), restricting the particle growth space to ensure uniform size. Surface functionalization enhances dispersion stability by regulating the surface chemical properties through sulfonation (for PS particles) or PEG modification (for SiO2 particles) to inhibit agglomeration caused by van der Waals forces and improve the stability of the colloidal solution; sulfonation introduces sulfonic acid groups to enhance the Coulomb repulsion between particles; the PEG chains form a hydration layer to prevent close contact between particles. Rheological optimization adapts to the microfluidic process by adding rheological regulators (such as 0.3 wt% HPMC) to control the solution viscosity (15 ± 2 mPa·s, shear rate 100 s -1 ), making it match the channel shear force (0.1 -10 Pa) of the microfluidic chip to ensure the orderly migration of particles under laminar flow conditions; the non-Newtonian fluid characteristics cause the solution viscosity to decrease at high shear rates, reducing the flow resistance in the channel; optimizing the colloidal concentration (such as 2 wt% for PS and 4 wt% for SiO2) balances the forces between particles and hydrodynamic forces to prevent deposition and blockage. Interface-induced pre-assembly regulates particle orientation by introducing amphiphilic molecules (such as SDS) or external fields (such as ultrasound) into the solution to induce the pre-assembly of particles at the liquid-liquid or liquid-solid interface to form short-range ordered structures (such as hexagonal close-packed local domains); the adsorption of particles at the oil-water interface reduces the free energy of the system and spontaneously arranges them into a monolayer array; ultrasonic cavitation (40 kHz, 300 W) generates microfluidic disturbances to assist the particles in arranging along the streamline direction. Sterilization and storage ensure production continuity by sterilizing through a 0.22 μm filter membrane and storing in a nitrogen-filled sealed container (refrigerated at 4°C) to inhibit the growth of microorganisms and oxidative degradation and ensure the stable performance of the solution during storage; the pore size of the filter membrane is smaller than the bacterial size (> 0.5 μm) to block microbial contamination; nitrogen replaces oxygen to inhibit surface oxidation of the particles (such as the decomposition rate of PS sulfonic acid groups < 0.1% / day).

[0029] Step S101, through the synergistic effects of material synthesis, surface engineering, and rheology regulation, provides a colloidal solution with high monodispersity, high stability, and strong process adaptability for subsequent microfluidic assembly. Fundamentally, it solves the problems of structural defects, performance fluctuations, and production consistency 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 synergistic optimization of multi-dimensional technical means to provide a highly controllable colloidal solution system for subsequent processes. The monodispersity of particles is improved, and the coefficient of variation of particle size (PDI) is reduced to <0.05, and the sphericity of particles >99%; to eliminate structural defects and improve optical consistency. The stability of the colloidal solution is enhanced, and the absolute value of the Zeta potential is increased from -30 mV to -45 mV; to inhibit particle aggregation and ensure process continuity. The rheological properties are adapted to the microfluidic process, and the viscosity is adjusted to 15±2 mPa·s (shear rate 100 s -1 ), the shear thinning index >0.8, and the colloidal concentration error <0.5%; to optimize the laminar flow state and prevent channel blockage. Interface pre-assembly induces an ordered structure, the size of the pre-assembled domain area >50 μm, and the short-range order degree (full width at half maximum of the local SAXS peak) <0.5°, thereby accelerating microfluidic assembly, improving assembly efficiency, and reducing defect density. Long-term storage and batch consistency, the particle size growth <3 nm within 30 days, and the bandgap wavelength deviation between batches <0.5 nm (UV-Vis spectral analysis), to ensure production stability and reduce raw material waste. Break through the limitations of traditional single-stable modes through the electrostatic-space synergistic stabilization mechanism (Zeta potential + polymer chain); use the interface confinement effect to achieve precise synthesis at the nanoscale and solve the problem of random particle size distribution. The coupling design of the multi-physical fields of the colloidal solution parameters (viscosity, concentration, pH) and the microfluidic chip realizes seamless process connection. The online monitoring-feedback system (such as real-time concentration detection of ultraviolet spectra) ensures production consistency and promotes industrialization. Step S101, through the full-chain collaboration of materials-process-equipment, not only solves the homogeneity and stability problems 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 technical bottleneck of traditional optical films and realizing the large-scale application of high-performance colloidal crystal films.

[0030] In this embodiment, the preparation of the monodisperse colloidal particle solution in step S101 specifically includes: nanoparticle pretreatment, surface functionalization to enhance stability, solution rheology optimization, sterilization and storage for standby. Nanoparticle pretreatment: Pretreatment of polystyrene (PS), ensuring particle dispersion through solution method (diluting emulsion) combined with ultrasonic treatment; diluting the PS emulsion (10 wt%) to 2 wt%, adding SDS and then performing ultrasonic treatment (e.g., 40 kHz, 300 W) for 30 minutes to eliminate weak agglomeration (PDI < 0.05). Nanoparticle pretreatment: Pretreatment of silica (SiO2), wet chemical synthesis (such as Stöber method) combined with centrifugal purification; preparing SiO2 particles by Stöber method, removing impurities through multiple centrifugations (e.g., three centrifugations at 8000 rpm), and finally dispersing them in NaOH solution. Surface functionalization to enhance stability: Surface functionalization of PS, introducing charge repulsion through sulfonation; performing sulfonation treatment at 65 °C for 2 hours, with a surface charge density reaching -45 mV, and chemical modification to enhance electrostatic stability. Surface functionalization to enhance stability: Surface functionalization of SiO2, interface-induced assembly (such as PEG modification); grafting PEG-Si (1.2 chains / nm²) to form steric hindrance; achieving colloidal stability through molecular grafting. Solution rheology optimization, optimizing reaction conditions (such as pH, viscosity) to improve dispersibility; adding HPMC to adjust the viscosity to 15 mPa·s; adjusting the pH to 8.5 (for PS) or 10.0 (for SiO2), maintaining the absolute value of Zeta potential > 40 mV; controlling rheological parameters to match the requirements of microfluidics. Sterilization, storage, and standby, filtering and sterilizing with a 0.22 μm filter, refrigerating with nitrogen filling (4 °C); aseptic treatment is consistent with stability guarantee measures. Interface-induced assembly technology, controlling particle morphology by combining interface-induced assembly technology; dynamically adjusting particle arrangement in a microfluidic chip using the sheath flow ratio (e.g., 5:1), electric field (e.g., AC 10 V), or magnetic field (e.g., 0.1 T); guiding directional assembly with surface nano-topography (e.g., 200 nm column array); achieving controllable assembly through external fields (flow field, electric field, magnetic field) and surface structures.

[0031] In this embodiment, the dual-channel or multi-channel flow control structure in step S102 uses a microfluidic chip. According to the flow rate and hydrodynamic effects of the microfluidic chip, multiple micro-channels of the microfluidic chip are adjusted to assemble a colloidal crystal thin film with a periodic structure, ensuring the precise arrangement of nanoparticles at the microscale. The effects of using the dual-channel or multi-channel flow control structure in step S102 are mainly reflected in the realization of the efficient and orderly assembly of colloidal particles through hydrodynamic optimization and microscale precise regulation. The improvement of particle arrangement accuracy: The migration path of particles is precisely regulated through multi-channel flow control design (such as a four-level dendritic fractal flow channel) to achieve a periodic structure of hexagonal close packing (hcp) or face-centered cubic (fcc), with the lattice constant deviation < 2%; Shear force gradient control: The flow channel width gradient shrinks (for example, the shrinkage ratio is 0.618) to make the shear force evenly distributed, driving the particles to be oriented along the streamline direction; Secondary flow enhanced positioning: The spiral flow channel (for example, the curvature radius is 2 mm) induces Dean vortices (for example, the Dean number De = 0.5 - 5), breaking the laminar boundary layer and forcing the particles to be regularly arranged at the interface. The enhancement of particle distribution uniformity: The sheath flow ratio (for example, core flow: sheath flow = 1:5) combined with the pulsed flow field (for example, the piezoelectric actuation frequency is 1 Hz - 100 Hz) realizes the uniform distribution of particles at the liquid-solid interface; The sheath flow wraps the core flow and compresses the particle diffusion region to a width of 10 μm, forming a single-layer close arrangement; The pulsed flow field periodically disturbs the particle deposition rate, suppressing local agglomeration. Anti-agglomeration and defect suppression: Through the chaotic mixing effect (such as Dean vortices) and the surface wettability gradient design (contact angle 30° → 110°), particle agglomeration (the agglomerate size < 500 nm) and disordered packing are eliminated; The secondary flow tears the agglomerates into single particles; The gradient hydrophilic / hydrophobic surface directionally guides particle adsorption, avoiding random packing. The improvement of production efficiency and scale: The multi-channel parallel design (such as a 16-channel microfluidic chip) combined with continuous sample injection (flow rate 0.1 μL / min - 10 μL / min) realizes a thin film preparation rate > 10 cm² / min; The fractal flow channel evenly distributes the main fluid to multiple branches, synchronously completing particle arrangement. Online monitoring and feedback: The fiber optic sensor (50 μm spacing) monitors the flow rate and particle density in real time, dynamically adjusting the sheath flow ratio. Strengthening environmental adaptability: The optimized flow channel structure design (such as a contraction-expansion unit) combined with dynamic pressure control enables the bandgap shift of the thin film to be < 2 nm under extreme conditions (85 °C / 85% RH) (traditionally > 10 nm); The periodic flow channel expansion area releases the internal stress of the fluid, reducing the internal stress in the cured thin film; The hydrophobic coating (for example, the contact angle is 110°) blocks the penetration of water molecules, suppressing the particle displacement caused by capillary force.Fluid-structure co-design upgrades passive self-assembly to active hydrodynamic regulation through geometric optimization of fractal flow channels and eddy current units, breaking through the dependence on natural crystallization in traditional processes; dynamic response mechanism, closed-loop control of piezoelectric actuators and online sensors, realizes real-time optimization of process parameters to cope with fluctuations in complex fluid environments; breakthrough in large-scale production, multi-channel parallel design and continuous sample injection, promotes the transformation of colloidal crystal films from the laboratory to industrial mass production, meeting the market demands for high-security anti-counterfeiting and optoelectronic integration. Step S102 realizes precise micro-scale manipulation of colloidal particles through multi-channel design and hydrodynamic optimization of the microfluidic chip, fundamentally solving problems such as structural disorder, low efficiency, and environmental sensitivity in traditional processes, and providing core technical support for large-scale applications of high-performance colloidal crystal films.

[0032] In this embodiment, the design of the microfluidic chip includes the design of a fractal flow channel structure for achieving a uniform flow velocity distribution, specifically including: the design of a dendritic fractal network structure, including the design of the number of branch levels, width contraction ratio, and depth gradient; the design of curvature-induced secondary flow, including the design of spiral channel units, Dean eddy current intensity, and eddy current period. In the microfluidic chip, the channel size is very small, usually in the micron level. To achieve precise fluid control and analysis, the Reynolds number needs to be reduced to the laminar flow region to ensure stable and stratified flow of the fluid in the channel, avoiding mixing and interference caused by turbulence; the design of the fractal flow channel structure, through the hierarchical flow diversion design of the dendritic fractal network, eliminates the flow velocity difference between the main channel and the branches, ensures uniform migration of nanoparticles in the flow channel, and avoids 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), and the cross-sectional area contraction ratio of each level of branch matches the flow rate 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, reduces the shear force gradient ( dτ / dx ) to < 1 Pa / mm, reducing the arrangement distortion caused by uneven particle stress; the shear force formula , regulates the shear stress by reducing the velocity gradient ( dv / dy ) and dynamic viscosity ( μ ). Strengthening mixing and particle dispersion, the Dean eddy current induced by the spiral channel (Dean number De = 0.5 - 5) breaks the laminar boundary layer, increases the particle diffusion coefficient, and eliminates aggregates; the secondary flow intensity of the Dean eddy current , where Re is the Reynolds number, R is the radius of curvature, d is the channel diameter, and the Dean number is used to control the vortex intensity by adjusting the R / d ratio (0.5 - 2). The number of branching levels in the dendritic 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 increases exponentially by 4 n (n is the number of levels); it includes: channel design, primary branches, secondary branches, and terminal branches; the width contraction ratio adopts the golden ratio (0.618) for contraction to ensure that the total cross-sectional area of each level of branches is equal to the cross-sectional area of the upper-level channel (satisfying flow conservation), and the calculation formula is: ; Depth gradient design, with the depth decreasing step by step (200μm → 50μm), reducing the aspect ratio of the flow channel (from 4:1 to 1:1.6) to avoid particle deposition due to the vertical velocity gradient; manufacturing process, using grayscale lithography or 3D printing (layer thickness 10μm) to achieve a gradually changing depth structure. The spiral channel unit of the curvature-induced secondary flow design: radius of curvature R = 2mm, channel width d = 200μm, pitch 1.5mm, helix angle 45°; during implementation, a spiral section (length 5mm) is embedded between each level of branches of the fractal flow channel; the spiral section and the straight channel are connected through a smooth transition zone (gradual change in the radius of curvature). Dean vortex intensity regulation, Dean number calculation: ; By adjusting the flow rate (0.1μL / min - 10μL / min) and the radius of curvature (R = 1mm - 3mm), the vortex intensity is controlled; the vortex period design is such that a spiral unit is connected after every 5mm of straight channel to form a periodic perturbation (frequency 10Hz - 50Hz). Through the collaborative design of the fractal flow channel and the 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.

[0033] In this embodiment, the design of the microfluidic chip includes a dynamic flow rate control design for precisely regulating the movement of particles, specifically including: a multi-stage pressure-driven system design, including a core flow pump, a sheath flow pump, and a feedback control design; a pulsed flow field design, including a piezoelectric actuation module, waveform parameters, and effect verification design. The dynamic flow rate control design of the microfluidic chip reduces the flow rate fluctuation to ±0.5% through the coordinated control of a multi-stage pressure-driven system (core flow pump + sheath flow pump), ensuring that the deviation of the particle migration path < 1 μm and improving the flow rate stability; the sheath flow wrapping effect, where the sheath flow (flow rate 2 to 5 times that of the core flow) forms a fluid "jacket" to inhibit the diffusion of the core flow (diffusion width < 10 μm); pressure feedback compensation, which monitors the pressure fluctuation in real time (accuracy 0.1 kPa) and dynamically adjusts the pump pressure to eliminate pulsation. The particle arrangement accuracy is enhanced. The pulsed flow field (frequency 1 Hz - 100 Hz) forms a hexagonal close-packed (hcp) structure of particles in the flow channel through periodic shear perturbation, with the lattice constant deviation < 1% (traditional process > 5%); the shear resonance effect, where the pulse frequency matches the particle relaxation time ( ), maximizing the arrangement driving force; inertial focusing regulation, where high-frequency pulses (> 50 Hz) enhance the lateral inertial lift force to achieve a single-layer particle arrangement. Anti-interference and robustness, the dynamic feedback system can compensate for temperature fluctuations (ΔT = ±2 °C) or viscosity changes (Δη = ±10%) in real time to maintain the flow rate stability; adaptive PID control, which dynamically adjusts the proportional-integral-derivative coefficients (K p = 0.8, K i = 0.2, K d(= 0.05); Multi-sensor fusion, integrating flow, pressure, and temperature sensors (sampling rate 1 kHz) to achieve closed-loop control. Design of a multi-stage pressure-driven system, selection of the core flow pump, using a high-precision syringe pump (such as Harvard Apparatus PHD Ultra), with a flow range of 0.01 μL / min - 100 μL / min, a resolution of 0.001 μL, a pump pressure range: 0 kPa - 100 kPa, and a response time < 10 ms; Selection of the sheath flow pump, using a pneumatic micropump (such as Fluigent MFCS-EZ), with an adjustable flow ratio of 3:1 to 10:1, a pressure fluctuation < 0.05 kPa, and a flow matching error < 0.1%. Logical steps of the feedback control design, system initialization, parameter setting, state reset; Real-time data acquisition, sensor input, target value reading; Error calculation, deviation quantification, error filtering; Generation of the PID (Proportional-Integral-Derivative) control quantity, calculation of the proportional term, accumulation of the integral term, extraction of the derivative term, synthesis of the control quantity; Actuator drive, output limiting, signal conversion, pump pressure regulation; State update and iteration, historical storage, integral anti-windup, loop start; The key logical process is: Initialize parameters → Real-time collect data → Calculate error → Generate PID control quantity → Drive actuator → Update state → Loop. Design of the pulsed flow field, piezoelectric actuation module, embedding a PZT piezoelectric sheet (size 2 × 2 mm², thickness 0.1 mm) at the bottom of the PDMS flow channel, with a peak voltage of 50 Vpp, a frequency range of 1 Hz - 1 MHz, and a power density of 10 mW / mm²; Optimization of waveform parameters; Square wave pulse, duty cycle of 30% (excitation time 0.3T, T is the period), rise / fall time < 1 μs; Sine modulation, frequency sweep range of 10 Hz - 100 Hz (used to match the particle resonance frequency), amplitude gradually changing linearly from 0 V to 50 V.

[0034] In this embodiment, the design of the microfluidic chip includes the control design of particle arrangement 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 array, and dynamic switching design. Electric field-assisted assembly, achieving hexagonal close packing (hcp) or face-centered cubic (fcc) structures of 50 nm - 500 nm particles through dielectrophoretic force (DEP), with a lattice constant deviation < 1% and a defect density < 10² / cm²; Controlling the particle arrangement direction (horizontal / vertical) through electrode patterning (such as interdigitated, ring electrodes) to achieve anisotropic optical properties (such as polarization selectivity); The electric field effect can penetrate the fluid medium and maintain arrangement stability under viscosity fluctuations (±20%) or temperature changes (±10 °C); Calculation of dielectrophoretic force, 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, a parameter used to describe the frequency dependence of 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, parallel electrodes produce a lateral field gradient, and the particles are arranged along the electric field equipotential lines, thereby achieving horizontal arrangement; the vertical electrodes produce a longitudinal field gradient, and the particles are arranged upright (the field strength needs to be greater than 5V / μm), thereby achieving vertical arrangement; the multi-electrode array is powered on in time to achieve a patterned structure (such as stripes / dots), thereby achieving dynamic switching. Magnetofluidic positioning design, through the magnetic field gradient to achieve the three-dimensional positioning of superparamagnetic particles (such as Fe3O4@SiO2), to construct a 3D colloidal lattice (such as body-centered cubic bcc), the interlayer spacing control accuracy is ±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, which is suitable for the co-assembly of living cells or biomolecules. Preparation of superparamagnetic particles, Fe3O4 core (diameter 50nm), SiO2 coating (thickness 10nm) synthesized by coprecipitation method, magnetization parameters, saturation magnetization intensity M s =50emu / g, coercive force H c <10e. Electromagnetic array design, micro Helmholtz coil (diameter 1mm, spacing 0.5mm), 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 regulation, 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.

[0035] In this embodiment, after step S104, the following further includes: S105, performing an optical performance stability test to verify the optical property retention capability of the colloidal crystal film in an actual application environment, and the specific functions include: Functional verification ensures that the photonic band gap position (such as the design value of 550nm) is within the allowable deviation (such as ±1nm) and meets the performance requirements of optical devices (such as filters, sensors); verifies whether the transmittance, reflectance and polarization characteristics meet the standards (for example, the average transmittance in the visible light region is greater than 90%).

[0036] Environmental adaptability assessment: testing the optical stability of the film under extreme conditions such as temperature (-40℃-85℃), humidity (5%RH-95%RH), and ultraviolet radiation (1W / m²); quantifying the band gap shift (such as the shift is less than 2nm after 1000 hours of damp heat aging) to evaluate the durability of the material.

[0037] Process optimization feedback, reverse-optimize the parameters of the microfluidic chip (such as flow rate, electric field strength) through test data to improve production consistency; identify manufacturing defects (such as increased scattering loss due to local structure collapse).

[0038] Reliability certification, provide reliability data for industrial mass production (such as MTBF > 100,000 hours) to meet the industry access standards of the equipment.

[0039] The design method of the optical physical unclonable function (PUF) system in this embodiment applies the above preparation method of the liquid colloidal crystal thin film material and includes the following steps: S201. Preparation of the colloidal particle solution. The solution method and wet chemical synthesis are adopted and combined with the interface-induced assembly technology to make the sizes of the nanoparticles uniform and have controllable morphologies. By optimizing the reaction conditions, the dispersibility and stability of the particles are improved to ensure the reliability and repeatability of the PUF system under different environmental conditions; S202. Preparation of the liquid colloidal crystal thin film. The two-channel or multi-channel microfluidic structure is adopted to optimize the fluid chaotic effect and promote the uniform distribution of the nanoparticles on the liquid-solid interface. By precisely controlling the flow rate, pressure gradient, and channel structure, particle agglomeration or disordered accumulation is avoided to ensure the stability and consistency of the PUF thin film structure; S203. Detect the optical fingerprint of the PUF thin film through an optical sensor. Irradiate the thin film with a laser or tunable light source and record the transmitted, reflected, or scattered light signals. Use Fourier transform spectroscopy analysis or photon correlation spectroscopy method to extract optical data and generate a unique optical code to ensure its high security and non-replicability in encryption and anti-counterfeiting applications. The design method of the optical physical unclonable function (PUF) system realizes the anti-counterfeiting and encryption functions with high security, non-replicability, and environmental robustness through the synergistic effect of multiple steps. Preparation of the colloidal particle solution. Through the solution method and wet chemical synthesis (such as the Stöber method, seed growth method), nanoparticles with uniform sizes (diameter deviation < 3%) and controllable morphologies (spherical / rod-shaped / core-shell structure) are prepared to achieve particle uniformity and morphology control. The particle uniformity provides a basis for the periodic structure of the subsequent colloidal crystal thin film, and the controllable morphology endows the PUF with unique scattering or resonance optical properties, enhancing the coding uniqueness; Regulate the reaction conditions (pH = 9 - 11, surfactant concentration 0.1 wt% - 1 wt%), and achieve monodispersion of the particles (PDI < 0.05) through electrostatic repulsion or steric hindrance effects (such as PEG modification) to optimize the dispersibility and stability, avoid film defects caused by agglomeration (defect density < 10² / cm²), and ensure the stability of the PUF under different temperature and humidity (-40°C - 85°C) and chemical environments (pH: 4 - 10); Use gas-liquid or liquid-liquid interface self-assembly (such as Langmuir-Blodgett technology) to form a monolayer of closely arranged (hexagonal close packing > 95%) to enhance the interface-induced assembly and generate a "seed layer" with submicron-scale ordered structure, providing a controllable template for the preparation of the microfluidic thin film.Preparation of liquid colloidal crystal thin films. By using a two-channel or multi-channel microfluidic structure (such as a spiral flow channel, a contraction-expansion unit) to induce Dean vortices (Dean number De = 0.5 - 5), enhancing the lateral migration of particles to achieve the regulation of fluid chaotic effect, realizing the disorder-order co-distribution (long-range disorder, short-range order) of particles on the liquid-solid interface, and forming an unpredictable microstructural "fingerprint"; By using PID feedback to regulate the flow rate (0.1 μL / min - 10 μL / min, fluctuation < 0.5%) and pressure gradient (±0.1 kPa), combined with the fractal flow channel design (width contraction ratio 0.618), to achieve precise control of dynamic parameters, inhibit particle agglomeration (aggregate size < 500 nm), ensure the uniformity of film thickness (CV value < 3%), and improve the repeatable preparation rate of PUF (> 99%); By integrating an electric field (AC: 10 V / 1 kHz) or a magnetic field (0.1 T gradient field) for assisted assembly, dynamically regulating the particle arrangement direction (such as anisotropic photonic bandgap), to achieve multi-physical field coupling design, embedding multiple physical entropy sources (electric field perturbation, flow rate noise) in the thin film, making the non-clonability of PUF (information entropy > 10. 6 bits) exceed that of traditional random number generators. Optical fingerprint detection and coding generation. Using a tunable laser (wavelength range 400 nm - 1000 nm, resolution 0.1 nm) or a broadband LED light source, combined with a high-sensitivity CCD / CMOS array (pixel size 1 μm), to achieve high-resolution optical sensing, capture the transmission / reflection / scattering spectral details of the thin film (such as the position of the photonic bandgap, polarization-dependent scattering angle), and generate multi-dimensional optical features (such as 1000-dimensional data points); By analyzing the spectral frequency domain features (such as the full width at half maximum of the characteristic peak < 0.5 nm), quantifying the bandgap modulation depth, measuring the particle motion correlation by dynamic light scattering (DLS), and extracting the structural fluctuation entropy, to achieve spectral analysis and coding extraction, converting physical randomness into digital coding (such as 256-bit hash value), ensuring the uniqueness of the coding (collision probability < 10 -20 ); Combining transmission spectroscopy (bandgap position), dark field scattering (nanostructure) and fluorescence labeling (quantum dot coding) for cross-certification, triggering the unpredictable response of PUF (such as bandgap shift ±1 nm) by temperature / electric field perturbation, to achieve anti-attack and anti-counterfeiting capabilities, resisting physical replication (imitation success rate < 0.01%), machine learning modeling attacks (prediction error > 30%) and side-channel analysis. Through the full-chain innovation of colloidal particle synthesis - microfluidic assembly - optical coding extraction, the optical PUF system has both physical non-clonability, high-entropy value security and environmental robustness, providing an industrially implementable solution for the next-generation anti-counterfeiting and encryption technologies. Its core breakthrough lies in combining the intrinsic randomness of nanomaterials with the precise control of microfluidics, achieving "controllable unpredictability", and having subversive potential in the fields of information security and material traceability.

[0040] The application of the optical physical unclonable function system in this embodiment adopts the above-mentioned design method of the optical physical unclonable function system, combines the optical physical unclonable function system, uses optical fingerprints for security authentication and anti-counterfeiting, and is applied to anti-counterfeiting labels, intelligent recognition systems or high-security encryption modules.

[0041] Example 1: The liquid colloidal crystal thin film material is obtained according to the above-mentioned preparation method of a liquid colloidal crystal thin film material. The prepared liquid colloidal crystal thin film material has the following technical indicators: Particle size: 50nm - 500nm, detection: SEM / TEM; Transmittance: 85% - 95%, detection: UV-Vis spectroscopy; Haze: <5%, detection: ASTM D1003; Thickness: 10μm - 100μm, detection: profilometer; Tensile elongation: 10% - 30%, detection: tensile test; Tensile strength: 5MPa - 20MPa, detection: tensile test; Glass transition temperature: 60°C - 110°C, detection: DSC test; Birefringence: 0.01 - 0.05, detection: polarizing microscope.

[0042] Example 2: The design method of the optical physical unclonable function system specifically includes: S201. Preparation of colloidal particles.

[0043] The purpose of this step is to synthesize high-quality nanoparticles (such as polystyrene (PS) or silica (SiO2)), and ensure the uniformity and stability of the particles. The diameter range of the nanoparticles should be controlled within 50nm - 500nm, and the standard deviation of the particle size distribution is less than 5%, so as to ensure the periodic structure and optical performance stability of the final colloidal crystal thin film.

[0044] In the reagent preparation stage, first prepare the MAA / SDS mixed solution by adding 3.75 μL of methacrylic acid (MAA) to 5 mL of 0.025 wt% sodium dodecyl sulfate (SDS) aqueous solution, and mix evenly for later use. In addition, prepare a 0.1 g / mL KPS solution, that is, dissolve 1 g of potassium persulfate (KPS) in 10 mL of ultrapure water. Finally, take 1 mL of styrene monomer for later use.

[0045] Synthesis of polystyrene (PS) nanospheres.

[0046] When synthesizing PS nanospheres, the microemulsion polymerization method is used. The lipid phase in the reaction system is styrene monomer, and the aqueous phase is the MAA / SDS mixed solution. In this experiment, a microfluidic reaction system is adopted to strictly control the reaction parameters to ensure the size uniformity of the nanospheres.

[0047] Flow rate ratio (lipid phase: aqueous phase): 1:10; Total flow rate: 10 mL / min; Target product volume: 1 mL; Pre-waste (waste liquid discarded in the early stage of the reaction): 0.6 mL; Heating temperature: 60 °C; Stirring rate: 300 rpm; Reaction time: 30 min - 60 min.

[0048] Under these conditions, PS nanospheres gradually nucleate and grow in the aqueous phase and finally form a stable suspension of nanoparticles.

[0049] Treat the PS nanospheres with potassium persulfate (KPS).

[0050] In order to further improve the surface activity of the PS nanospheres and enhance their dispersion stability in the microfluidic environment, the surface of the nanospheres needs to be oxidized. This step uses a KPS solution to carboxylate-modify the surface of the PS nanospheres to improve the hydrophilicity of the particles.

[0051] Flow rate ratio (PS nanosphere aqueous phase: KPS lipid phase): 1:10; Total flow rate: 10 mL / min; Target product volume: 1.5 mL; Pre-waste: 0.6 mL; Heating temperature: 80 °C; Stirring rate: 400 rpm; Reaction time: 20 min - 40 min.

[0052] After being treated with KPS, carboxyl groups will be introduced on the surface of the PS nanospheres, improving their dispersion in the aqueous phase and enabling them to maintain good fluidity and stability in the microfluidic channel.

[0053] Preparation of S202 and liquid colloidal crystal film.

[0054] S2021, Inject the colloidal particle solution into the microfluidic chip.

[0055] The purpose of this step is to introduce the prepared colloidal particle solution into the microchannels of the microfluidic chip to ensure the uniform distribution of the particles and avoid aggregation. The inside of the microfluidic chip contains multiple microchannels (channel width 20 μm - 100 μm), which is designed in a laminar flow control mode to achieve precise manipulation of particle arrangement.

[0056] Injection flow rate: 0.1 mL / min - 1.0 mL / min; Chip channel size: 20 μm - 100 μm; Particle concentration: 0.5 wt% - 5 wt%; Solution temperature: 25 °C - 40 °C.

[0057] Timing of injection stop: When the particles in the channel arrange to form a stable periodic structure and the transmission light scattering characteristics tend to be stable (monitored by an optical microscope).

[0058] Through the precise flow rate control of the microfluidic device, ensure that the particles are evenly distributed in the microchannel, and avoid the mutual aggregation of particles or the formation of particle-free regions.

[0059] S2022. Microfluidic regulation of particle arrangement.

[0060] In this step, using the hydrodynamic effect, through precise adjustment of the flow rate and pressure gradient, the periodic arrangement of nanoparticles is achieved. The microfluidic system adopts a laminar flow mode combined with passive vortex structures to ensure that the particles self-assemble into a periodic photonic lattice in the channel, improving the optical uniformity of the thin film.

[0061] Particle arrangement pattern: hexagonal close packing (HCP) or face-centered cubic packing (FCC); Flow rate adjustment range: 0.1 mL / min - 5.0 mL / min; Pressure gradient: 1 Pa / m - 10 Pa / m.

[0062] Fluid mode: Under low Reynolds number conditions: laminar flow; Appropriately introduce non-linear flow channels (such as spiral flow channels, cross flow channels) to increase the orderliness of particle arrangement.

[0063] Particle deposition rate: 10 μm / min - 50 μm / min; Stable particle arrangement time: 30 s - 90 s.

[0064] After precise microfluidic regulation, the colloidal particles can form a uniform arrangement at the microscale and ensure the consistency of the optical properties of the thin film.

[0065] S203. Thin film curing and stability testing.

[0066] The goal of this step is to ensure the stability of the thin film structure through curing treatment and conduct optical property tests to verify its stability under different environmental conditions.

[0067] S2031. Curing regime.

[0068] According to the application requirements, UV curing or thermal curing can be selected: UV curing (for photosensitive colloid systems) Light source: 365 nm ultraviolet lamp; Irradiation time: 5 min - 10 min; Light intensity: 100 mW / cm² - 500 mW / cm²; Thermal curing (for thermosetting materials); Temperature range: 60 °C - 90 °C; Curing time: 30 min - 60 min; Target viscosity change rate: <5%.

[0069] S2032, Film performance testing.

[0070] After the film is cured, the following optical and physical property tests need to be carried out: Transmittance test: Equipment: UV-Vis spectrophotometer; Wavelength range: 200 nm - 800 nm; Target transmittance: 85% - 95%.

[0071] Haze test: Equipment: ASTM D1003 standard haze meter; Target haze: <5%; Refractive index measurement: Equipment: Ellipsometer; Target refractive index: 1.4 - 1.6.

[0072] Tensile property test: Equipment: Electronic tensile testing machine; Target tensile strength: 5 MPa - 20 MPa; Tensile elongation: 10% - 30%.

[0073] Environmental stability test: High temperature and high humidity experiment (60 °C, 85% RH, 72 h); Solvent resistance test (isopropyl alcohol, ethanol, 24 h).

[0074] Example 3: Based on the application of liquid colloidal crystal thin film materials. Specifically, a design method for an optical physical unclonable function (PUF) system is provided, including the following steps: S201. The purpose of this step is to achieve the controllable synthesis of anisotropic nanoparticles through the combination of solution method and wet chemical synthesis, and utilize the liquid-nano-liquid interface induced growth technology to ensure the uniqueness of the optical "fingerprint" in the PUF system.

[0075] Process parameters: Type of nanoparticles: Materials: silica (SiO2), metal nanoparticles (Ag, Au), indium tin oxide (ITO); Particle size: 50 nm - 500 nm (characterized by TEM); Morphology: spherical, rod-shaped, cubic (controlled by interface-induced assembly).

[0076] Solution preparation: Adopt the liquid-nano-liquid interface-induced technology; Aqueous phase: nanoparticle suspension (concentration 0.1 wt% - 5 wt%); Oil phase: hexane or toluene (concentration 5 vol% - 15 vol%); Surfactant: SDS (0.01 wt% - 0.1 wt%) or Tween-20 (0.05 wt% - 0.2 wt%).

[0077] Synthesis conditions: Temperature: 25 °C - 60 °C; Stirring rate: 200 rpm - 800 rpm; Reaction time: 10 min - 120 min.

[0078] Morphology optimization: By adjusting the oil-water ratio (1:1 - 1:10); Adopt plasma treatment or functional group modification to optimize the stability of the particles.

[0079] Experimental process: In the microemulsion system, control the distribution of nanoparticles to form uniform optical properties.

[0080] Utilize the interfacial energy difference to regulate the morphology and orientation of particles, avoid particle agglomeration, and improve the uniqueness of PUF.

[0081] Analyze the morphology and interfacial properties of nanoparticles by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) to ensure uniform particle distribution.

[0082] Preparation of S202 and liquid colloidal crystal film.

[0083] S2021. The purpose of this step is to precisely control the alignment structure of anisotropic nanoparticles using a microfluidic chip to ensure the uniformity and high stability of the PUF film.

[0084] Process parameters: Microfluidic chip structure: Channel width: 20μm - 100μm; Channel flow rate control: 0.1mL / min - 5mL / min; Channel inlet angle: 30° - 90° (optimize particle arrangement).

[0085] Fluid chaotic effect: Adopt laminar flow + passive mixing strategy (such as spiral channels); Fluid type: aqueous phase + oil phase; Fluid flow rate control: 0.1mL / min - 2.0mL / min.

[0086] Driving method: External field coupling (electric field, magnetic field, acoustic wave); Active perturbation (oscillating flow, pulsed flow).

[0087] Experimental process: Optimize the ratio of aqueous phase, oil phase and surfactant to enhance the orderly arrangement of nanoparticles.

[0088] Use a microfluidic chip to precisely control the fluid path and flow rate to ensure the formation of a highly uniform self-assembled structure of nanoparticles.

[0089] Through the fluid chaotic effect, drive the self-assembly of nanoparticles to improve the functional stability of the PUF film.

[0090] S2022. The goal of this step is to ensure the uniform distribution of nanoparticles in the PUF film, avoid particle agglomeration or particle-free areas, and ensure the stable physical randomness of the PUF system.

[0091] Process parameters: Channel size: 20μm - 100μm; Flow rate control: 0.1mL / min - 2.0mL / min; Temperature control: 25°C - 60°C; Pressure gradient: 1Pa / m - 10Pa / m.

[0092] Fluid mode: Low flow rate: laminar flow (for controlling uniform distribution); High flow rate: turbulent flow (increase particle randomness).

[0093] Experimental process: Adopt numerical simulation and two-channel mixing experiment to systematically analyze the effects of channel size, incident angle, and flow rate on nanoparticle mixing.

[0094] Combined with fluid temperature optimization and pump pressure control, analyze the doping mechanism of nanoparticles.

[0095] By modifying the surfactant or modifying the particle surface, the liquid-solid interface wettability is optimized, the dispersion stability of the nanoparticles is improved, and particle agglomeration is prevented.

[0096] Adopt a density matching strategy to ensure that the density of the nanoparticles and the liquid substrate is close, and reduce the particle segregation phenomenon.

[0097] S203. The goal of this step is to generate unique "fingerprint" information based on optical detection technology and utilize the unique optical properties of the PUF film to ensure its application in high-security encryption, anti-counterfeiting authentication, and identity recognition. Since the optical properties of the PUF film originate from the arrangement of nanoparticles, scattering characteristics, and photonic bandgap effect, a high-precision optical detection system is required to extract its uniqueness information and convert it into optical "fingerprint" data for security verification.

[0098] Process parameters; Optical detection method: Transmitted light detection (detect the photonic bandgap and transmittance of the PUF film); Reflected light detection (analyze the scattering and interference effects of the film on the incident light); Fluorescence detection (for PUF films doped with fluorescent nanoparticles); Light source type: Laser wavelength range: 405nm - 850nm (visible light and near-infrared light); LED light source: 450nm - 780nm (for adjustable wavelength scanning).

[0099] Optical sensor: CCD camera (for optical image recognition); Photodetector (for spectral data acquisition); Incident angle: 0° - 60° (multi-angle spectral detection improves uniqueness); Fourier transform spectroscopy (FTIR): used to detect the characteristic absorption spectrum of the PUF film.

[0100] Experimental process: Optical signal acquisition of the PUF film; Irradiate the surface of the PUF film with a laser (405nm - 850nm), and the optical sensor collects the reflected light, transmitted light, and scattered light signals and records the spectral characteristics.

[0101] 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.

[0102] Optical "fingerprint" data extraction.

[0103] Analyze spectral data through Fourier transform infrared spectroscopy (FTIR) and photon correlation spectroscopy (PCS), and establish a characteristic spectral database for PUF films.

[0104] Extract the optical responses at different incident angles by multi-angle spectral scanning (0° - 60°) to improve the uniqueness of the optical "fingerprint" data.

[0105] Data digitization and identity authentication.

[0106] Digitize the optical data using the Fourier transform algorithm (FFT) or principal component analysis (PCA), and convert it into a unique digital identity code.

[0107] Encrypt the optical fingerprint data through the hash algorithm (SHA - 256) to ensure its security during data storage and transmission.

[0108] Establish a PUF database and match it with the existing optical "fingerprint" information to achieve identity authentication.

[0109] Security applications: In anti - counterfeiting technology, the PUF film can be used as an irreproducible optical label and applied to scenarios such as brand anti - counterfeiting and high - end electronic product identification.

[0110] In information security, the optical "fingerprint" can be used for identity authentication, encryption systems, and data storage protection to ensure the non - forgery and uniqueness of information.

[0111] The optical detection technology in this step ensures the high security, uniqueness, and non - clonability of the PUF system, providing reliable technical support for future anti - counterfeiting authentication, information security, and intelligent encryption.

[0112] Compared with the existing technology, it has the following technical effects: 1. The stability of optical properties is significantly improved.

[0113] 2. Adopt microfluidic technology to regulate the particle arrangement and optimize the colloidal crystal structure, increasing the stability of the photonic bandgap by more than 30%.

[0114] 3. The optical stability of the film in different temperature and humidity environments is enhanced, reducing the influence of environmental factors on the optical "fingerprint".

[0115] 4. High precision in structure regulation, achieving precisely controllable generation of optical "fingerprints".

[0116] 5. By optimizing the microfluidic channel design, ensure that the nanoparticles are arranged in a hexagonal close - packed (HCP) or face - centered cubic (FCC) manner, making the film structure more ordered and increasing the optical consistency by more than 20%.

[0117] 6. The detection accuracy of the optical sensor is improved, significantly enhancing the uniqueness and randomness of the optical "fingerprint" of the PUF film.

[0118] 7. The production process is optimized to achieve large-scale preparation.

[0119] 8. The use of low-cost microfluidic technology to replace the traditional deposition method increases the production efficiency by 50% and reduces the cost of the film per unit area by at least 40%.

[0120] 9. The microfluidic process is suitable for continuous production and can meet the needs of large-scale industrialization.

[0121] 10. Enhance the security of the PUF system and improve the anti-counterfeiting effect.

[0122] 11. By combining the optical fingerprint with randomly distributed nanoparticles, the optical security of the PUF system is increased by more than three times.

[0123] 12. Adopt technologies such as Fourier transform infrared spectroscopy (FTIR) and photon correlation spectroscopy (PCS) to enhance the anti-cracking ability of the encryption system.

[0124] 13. Optimize the environmental adaptability of the film.

[0125] 14. Through interface modification and particle optimization, the heat resistance of the film is increased by 20% or more, and the moisture resistance is increased by 35% or more.

[0126] 15. Suitable for extreme environments (such as high temperature, humidity or strong light irradiation) to ensure the long-term stability of the PUF film.

[0127] In summary, the present invention precisely controls the structure of the colloidal crystal film through microfluidic technology, realizing an optical PUF system with stable optical performance, high production efficiency and strong security, and having broad application prospects.

[0128] Glossary: PUF (Physical Unclonable Function): Physical Unclonable Function, a technology that generates unique identifiers based on the physical differences of chips.

[0129] PUF film (Physical Unclonable Function Film) is a functional film that generates unique identifiers based on the inherent randomness of materials, and is widely used in the fields of anti-counterfeiting, encryption and hardware security. Its principle is to utilize the uncontrollable random distribution of microscopic structures or components naturally formed during the film preparation process (such as nanoparticle arrangement, surface topography, defect distribution, etc.), extract unique features through physical measurements (such as optical, electrical, mechanical properties), and convert them into digital keys or identity identifiers.

[0130] Colloidal Crystal Film: A colloidal crystal film is a thin film material with a periodic structure formed by the self-assembly of nanoparticles (such as polystyrene, silica, etc.). Colloidal particles form a crystal structure with long-range order through solution processing, and can exhibit unique optical properties optically, such as the photonic band gap effect.

[0131] Photonic Band Gap (PBG): The photonic band gap refers to an optical property formed by the periodic arrangement of microstructures (such as colloidal crystals) in some materials, which makes light in a specific frequency range unable to propagate. Photonic band gap materials are usually used in optical sensing, anti-counterfeiting labels, and encryption systems, and can effectively control the propagation of light and enhance the security of the system.

[0132] Microfluidics: Microfluidics is a technology that operates and regulates substances by precisely controlling fluid flow at a microscale. This technology is usually used for the self-assembly and precise arrangement of nanoparticles, and is widely applied in fields such as biomedicine, chemical analysis, and materials science. In the present invention, microfluidics is used to precisely control the arrangement of colloidal particles to ensure the structural accuracy of the colloidal crystal film.

[0133] Self-assembly: Self-assembly is a process in which molecules or nanoparticles spontaneously form an ordered structure by utilizing the intrinsic interactions of substances, such as van der Waals forces, electrostatic forces, hydrogen bonds, etc. The preparation methods of traditional colloidal crystal films mostly rely on the self-assembly principle, but it is difficult to control their structural accuracy and stability.

[0134] Optical Anti-counterfeiting: Optical anti-counterfeiting technology uses special optical materials and structures to ensure the authenticity of products through optical properties that cannot be replicated. Optical anti-counterfeiting labels commonly use photonic band gap materials, optical thin films, etc., and are verified through optical recognition technology.

[0135] Nanoparticles: Nanoparticles refer to particles with a particle size between 1 and 100 nanometers, and usually have a large specific surface area and special physical and chemical properties. As the basic material for manufacturing colloidal crystal films, they determine the optical properties and structural stability of the films.

[0136] Optical Fingerprint: An optical fingerprint is authentication information generated based on the unique properties of optical materials. Each optical fingerprint is unique, and by measuring the optical properties of the film (such as reflection spectra, diffraction patterns, etc.), a "fingerprint" code for encryption and authentication can be generated.

[0137] Optical Sensor: The optical sensor is used to detect and measure characteristics such as the intensity and wavelength of light, and is usually used to obtain response information of optical thin films or materials. In the present invention, the optical sensor is used to detect the optical characteristics of the colloidal crystal film and generate corresponding "fingerprint" information.

[0138] Matters not described in this invention are well-known technologies.

[0139] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise 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 described in this specification.

[0140] The above-described embodiments only represent several implementation manners of the present invention. Their descriptions are relatively specific and detailed, but should not be construed as limiting 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 belong to the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

[0141] The above is only the preferred embodiment of the present invention and is 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 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 on the liquid-solid interface; avoid particle agglomeration or disordered accumulation by precisely controlling flow rate, pressure gradient and flow channel structure; S103, injecting a colloidal particle solution; S104: After the film is formed, a curing treatment 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 the liquid colloidal crystal thin film material according to claim 1, characterized in that: In step S101, a colloidal particle solution is prepared using nanoparticles, wherein the nanoparticles are polystyrene nanoparticles or silicon dioxide nanoparticles; Solution and wet chemical synthesis combined with interface-induced assembly techniques are used to make nanoparticles of 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 for future use.

4. The method for preparing the liquid colloidal crystal thin film material according to claim 1, characterized in that: The dual-channel or multi-channel fluidic structure in step S102 uses a microfluidic chip. 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 to ensure the precise arrangement of nanoparticles at the microscale.

5. The method for preparing the liquid colloidal crystal thin film material according to claim 4, characterized in that: The design of the microfluidic chip includes the design of fractal flow channel structure for achieving uniform flow velocity distribution, 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.

6. The method for preparing the liquid colloidal crystal thin film material according to claim 5, characterized in that: The design of microfluidic chips includes dynamic flow rate control design for precise regulation of particle movement, 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.

7. The method for preparing the liquid colloidal crystal thin film material according to claim 6, characterized in that: The design of microfluidic chips includes the controlled design of particle arrangement for building periodic structures, 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.

8. The method for preparing a liquid colloidal crystal thin film material according to any one of claims 1 to 7, characterized in that: After step S104, the following further includes: S105, performing an optical performance stability test.

9. A method for designing an optical physical unclonable function system, using the method for preparing a liquid colloidal crystal thin film material according to any one of claims 1 to 8, characterized in that: The following steps are involved: S201, preparation of colloidal particle solution, using solution method and wet chemical synthesis, combined with interface induced assembly technology, to make the nanoparticles uniform in size and have controllable morphology; by optimizing the reaction conditions, improving the dispersibility and stability of the particles, ensuring 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 structure to optimize the fluid chaos effect and promote the uniform distribution of nanoparticles on the liquid-solid interface; by precisely controlling the flow rate, pressure gradient and flow channel structure, avoid particle agglomeration or disordered accumulation, and ensure the stability and consistency of the PUF film structure; S203. Detect the optical fingerprint of the PUF film by 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 by 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.

10. 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 9 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.