A photonic crystal indicator tag for cryogenic monitoring

Abstract

The present application relates to a kind of photonic crystal indicating label for cryogenic monitoring, belong to indicating material field.It is characterized in that with photonic crystal as temperature response material, after being uniformly mixed with phase transition temperature adjustable solvent, directional freezing is carried out at the freezing point temperature of solvent, the principle that ice crystal formation and melting caused by temperature fluctuation change photonic crystal arrangement and cause label discoloration is used, temperature monitoring of low-temperature storage product is realized.The indicating label produced by the present application has the advantages of simple preparation method, wide monitoring temperature range, high sensitivity, etc., as indicating label to monitor the temperature fluctuation of cold chain logistics product.

Description

I. Technical Field

[0001] This invention relates to a photonic crystal indicator tag for low-temperature monitoring, belonging to the field of indicator materials. II. Background Technology

[0002] Cold chain logistics maintains product quality and shelf life by controlling temperature throughout the distribution process to ensure goods remain in a suitable storage and transportation environment. This is particularly important for transported goods requiring specific temperature preservation, such as food, pharmaceuticals, vaccines, and excised organs. However, my country's cold chain logistics development is still imperfect, with the main problems being: firstly, relatively lagging technology and facilities, unable to meet the needs of accurate, real-time, and continuous temperature monitoring; and secondly, complex temperature monitoring equipment increases operational difficulty and cost. In cold chain logistics, multiple temperature sensors and data loggers are typically installed to monitor temperatures in different areas. These devices often require complex setup and calibration, as well as operation and maintenance by specialized technicians, increasing both operational difficulty and costs.

[0003] Photonic crystal temperature indicators are a recently emerging method of temperature monitoring. A photonic crystal is a regular optical structure made by periodically arranging media with different refractive indices. The photonic bandgap of this material can block photons of specific frequencies, producing a particular structural color. The arrangement of the photonic crystal is influenced by its surrounding chemical or physical environment (such as temperature, electric field, magnetic field, etc.), resulting in different structural colors.

[0004] [Patent Document 1]. A temperature-controlled self-destructing photonic crystal tag (Patent No.: CN114924335A, Publication Date: 2022.08.19). The indication principle of this invention is that when the temperature is higher than the phase transition temperature of the thixotropic agent, the thixotropic agent self-destructs and mixes with the photonic crystal to form a structural color. The drawback of this invention is that it requires thixotropic self-destruction to achieve color change, and the color development mechanism is complex.

[0005] [Patent Document 2]. A photonic crystal material with irreversible temperature responsiveness and its preparation method (Patent No.: CN110908145A, Publication Date: 2020.03.24). The photonic crystal described in this invention forms an ordered structure under magnetic field-induced or non-magnetic field-induced conditions. The contained phase transition material undergoes a phase transition when the temperature exceeds the phase transition temperature, thereby changing the ordered structure of the photonic crystal and producing structural color. The drawback of this invention is that the ordered structure of the photonic crystal requires magnetic field or non-magnetic field induction, and the preparation process is relatively complex.

[0006] This invention uses photonic crystals as temperature-responsive materials. After being uniformly mixed with a solvent with adjustable phase transition temperature, the mixture is directionally frozen at the freezing point of the solvent. The principle of changing the label color by altering the arrangement of the photonic crystals due to the formation and melting of ice crystals induced by temperature fluctuations is used to achieve temperature monitoring of products stored at low temperatures. III. Summary of the Invention

[0007] Technical issues

[0008] The purpose of this invention is to provide a photonic crystal indicator tag for low-temperature monitoring. Its key feature is that it uses a photonic crystal as the temperature-responsive material, which is uniformly mixed with a solvent with an adjustable phase transition temperature and then directionally frozen at the solvent's freezing point. The tag changes color due to the alteration of the photonic crystal arrangement caused by temperature fluctuations inducing ice crystal formation and melting, thus enabling temperature monitoring of products stored at low temperatures. The indicator tag produced by this invention has advantages such as simple preparation, a wide monitoring temperature range, and high sensitivity, making it suitable for monitoring temperature fluctuations in cold chain logistics products.

[0009] Technical Principles

[0010] The photonic crystal indicator tag consists of photonic crystal particles, a matrix, and a phase change material (PCM). The freezing point of the PCM can be adjusted based on the mass ratio of water within it. The PCM fills the space between the photonic crystal particles and the matrix. When the photonic crystal indicator tag is directionally frozen below the PCM's freezing point, the resulting oriented, long-range ordered ice crystals displace the non-aqueous matrix phase and shorten the distance between the photonic crystal particles. This alters the periodic, ordered arrangement of the photonic crystal particles, giving them a specific structural color. When the temperature exceeds the set freezing point, the ice crystals melt into water and remix with the matrix. The distance between the photonic crystal particles increases, and the periodic arrangement changes again. At this point, the structural color of the photonic crystal particles changes, alerting the user to a significant temperature fluctuation exceeding the acceptable range.

[0011] Technical solution

[0012] This invention provides a photonic crystal indicator tag for cryogenic monitoring. The tag consists of photonic crystal particles that exhibit different structural colors under different periodic arrangements and a phase transition material with an tunable freezing point. The technical solution is as follows:

[0013] 1. This photonic crystal indicator tag is a composite material consisting of photonic crystal particles, a matrix, and a phase change material. A significant number of photonic crystal particles are regularly arranged in the matrix to form an ordered structure, while the phase change material fills the spaces between the photonic crystal particles and the matrix.

[0014] The freezing point of phase change materials varies with the water content ratio, ranging from -80℃ to -10℃.

[0015] This photonic crystal indicator tag utilizes the space-occupancy effect of long-range ordered ice crystals formed by directional freezing to squeeze out the non-aqueous matrix, thereby adjusting the gaps and periodic arrangement of photonic crystal particles, which in turn causes the reflection wavelength of the photonic crystal to red-shift or blue-shift, resulting in a change in the tag color.

[0016] 2. In the technical solution of the present invention, the structural color change time of the photonic crystal indicator tag at the freezing point temperature is 10s to 70s.

[0017] 3. In the technical solution of the present invention, the proposed photonic crystal indicator tag for low-temperature monitoring is affected by at least one of the photonic crystal particle type, arrangement, phase change material type, and matrix composition, and the photonic crystal indicator tag has different structural colors at different temperatures.

[0018] 4. In the technical solution of the present invention, the phase change material is selected from at least one of ionic liquids, organic solvents, salt solutions and sugars, and its freezing point can be changed within a wide range depending on the mass ratio of water after mixing with water.

[0019] Preferably, the ionic liquid is selected from at least one of 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt, triethylmethylammonium tetrafluoroborate, and bis(trifluoromethanesulfonyl)imide salt ionic liquids;

[0020] Preferably, the organic solvent is selected from at least one of glycerol, ethylene glycol, propylene glycol, and ethanol;

[0021] Preferably, the salt solution is selected from at least one of sodium chloride, magnesium chloride, sodium nitrate, calcium chloride, and potassium sulfate;

[0022] Preferably, the sugar is selected from at least one of sucrose, fructose, glucose, trehalose, and arabinose.

[0023] 5. In the technical solution of the present invention, the matrix is ​​selected from at least one of high molecular weight organic compounds, oligomers, oils and waxes.

[0024] Preferably, the flowable polymer compound is selected from at least one of polyethylene glycol, polystyrene, polyvinyl chloride, polyacrylamide, and polyvinylpyrrolidone;

[0025] Preferably, the oligomer is selected from at least one of polyester resin, epoxy resin, polyurethane acrylate, epoxy acrylate, and polyether acrylate;

[0026] Preferably, the wax is selected from at least one of paraffin wax, ceresin wax, beeswax, galvanic wax, and coconut wax.

[0027] 6. In the technical solution of the present invention, the photonic crystal indicator tag for low-temperature monitoring is provided, wherein the photonic crystal particles are obtained by at least one of the following methods: coprecipitation self-assembly, solvent evaporation, sol-gel method, vapor deposition, and centrifugal sedimentation.

[0028] 7. Preferably, the volume ratio of the photonic crystal particles to the phase change material is 1 to 10000:1; in the present invention, the larger the volume ratio of the photonic crystal particles to the phase change material, the shorter the structural color change time and the more obvious the color change.

[0029] 8. Preferably, the adjustable freezing point temperature range of the present invention is -80℃ to -10℃; for example, -80℃, -70℃, -20℃, -10℃;

[0030] Preferably, the photonic crystal indicator tag for low-temperature monitoring proposed in this invention has photonic crystal particles with a particle size between 30 nm and 3000 nm.

[0031] Preferably, the regularly arranged photonic crystal particles have a two-dimensional or three-dimensional structure;

[0032] Preferably, the interparticle spacing of the photonic crystal is between 0.1 nm and 3000 nm.

[0033] 9. The photonic crystal indicator tag for low-temperature monitoring proposed in this invention, wherein the photonic crystal particles are selected from one or any combination of inorganic compounds, metal oxides, metal particles and semiconductors;

[0034] Preferably, the inorganic compound is selected from at least one of silicon dioxide, silicon carbide, titanium carbide, zinc sulfide, and silver chloride;

[0035] Preferably, the metal oxide is selected from at least one of zinc oxide, aluminum oxide, iron(III) oxide, and ferric oxide;

[0036] Preferably, the metal particles are selected from at least one of gold, silver, copper, iron, nickel, and platinum;

[0037] Preferably, the semiconductor is selected from at least one of titanium trioxide, titanium dioxide, gallium nitride, and gallium arsenide.

[0038] 10. The photonic crystal indicator tag for low-temperature monitoring proposed in this invention, wherein the method for preparing the temperature-responsive solid-state photonic crystal assembly includes the following steps:

[0039] (1) Adjust the mass ratio of water in the phase change material to set the phase change temperature;

[0040] (2) Prepare a pregel suspension of photonic crystal particles by combining the matrix, photonic crystal particles and phase change material;

[0041] (3) Pour the pregel suspension into the template and freeze it in a directional manner so that the ice crystals are oriented and long-range ordered.

[0042] Beneficial effects

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] (1) When the ambient temperature is higher than the freezing point of the material, the ice crystals melt into water and mix with the non-aqueous phase in the phase change material again. At this time, the distance between the photonic crystal particles increases and the periodic arrangement order changes, thus producing structural color.

[0045] (2) Photonic tags can determine whether the stored items are overheated during cold chain storage and transportation simply by visual observation. This process is not affected by environmental pH, humidity, gas composition, or the properties of the stored items, but is only affected by temperature and has high monitoring accuracy.

[0046] The photonic crystal indicator tag has a simple manufacturing process, contains no hazardous reagents, has a stable label structure and color, and a long service life, making it suitable for long-term or short-term cold chain transportation and storage. IV. Detailed Implementation

[0047] Example 1

[0048] The fabrication process of the photonic crystal indicator tag for low-temperature monitoring provided in this embodiment is as follows:

[0049] (1) SiO2 particles were prepared according to the well-known Stobber method. 12 mL of tetraethoxysilane, 140 mL of ethanol, 50 mL of water, and 20 mL of ammonia were placed in a constant temperature stirrer and heated and stirred at 60 °C for 5 hours to obtain a SiO2 photonic crystal nanosphere solution. Subsequently, the solution was dried and crystallized at 60 °C to obtain SiO2 photonic crystal nanospheres with an average particle size of 187.5 nm. A certain amount of epoxy resin was mixed with a 60% ethylene glycol solution (freezing point -51 °C) to form a mixture. The prepared SiO2 particles were uniformly dispersed in the mixture to form a photonic crystal assembly with a SiO2 colloidal particle mass fraction of 10 wt%. The photonic crystal assembly was filled into a hollow glass cavity mold with a volume of 5 × 1 × 0.5 cm (hereinafter referred to as the mold). The bottom surface of the mold was vertically contacted with a cryogenic liquid at a temperature of -60 °C, and the mold was slowly pushed into the cryogenic liquid along the long side at a speed of 1 mm / s until the mold was completely submerged to achieve directional freezing of ice crystals.

[0050] (2) The temperature of the cryo-liquid is much lower than the freezing point of the photonic crystal assembly. Therefore, when the photonic crystal assembly comes into contact with the cryo-liquid, the aqueous phase freezes rapidly. At this time, the ice crystals expel the epoxy resin and change the spacing and periodic arrangement of the nano-SiO2 particles, which macroscopically manifests as a blue shift in the structural color of the photonic crystal assembly. As the mold is gradually immersed in the cryo-liquid, the structural color shifts uniformly upward until the photonic crystal assembly completely changes color. Thus, the photonic crystal indicator tag was successfully fabricated.

[0051] The photonic crystal indicator tag provided in this embodiment has an indicating temperature of -51℃. When the ambient temperature is higher than this temperature, the ice crystals melt into water and remix with the matrix, increasing the gaps between the nano-SiO2 particles and changing their periodic arrangement order. Macroscopically, this manifests as the photonic crystal indicator tag changing from blue to orange. At this point, unless it is refrozen in step (1), it cannot be restored to its original structural color before thawing. In actual use, directional freezing conditions are usually not met. Therefore, when the structural color of the photonic crystal indicator tag changes, it indicates that the ambient temperature has been or is currently higher than the set freezing point temperature.

[0052] Example 2

[0053] The fabrication process of the photonic crystal indicator tag for low-temperature monitoring provided in this embodiment is as follows:

[0054] (1) A 40% ethylene glycol solution (as a phase change material, freezing point -25℃) was mixed with polyethylene glycol diacrylate (PEGDA) at a volume ratio of 1:1, and 10nm gold nanoparticles were dispersed in the mixture to form a photonic crystal assembly with a gold nanoparticle mass fraction of 30wt%. This photonic crystal assembly was injected into a PE plastic mold with internal dimensions of 0.1mm × 10mm × 30mm. After the photonic crystal assembly completely filled the plastic mold, it was slowly and vertically pushed into a cryogenic liquid at a temperature of -40℃ at a speed of 1mm / s. The photonic crystal assembly in contact with the cryogenic liquid exhibited a distinct structural color, forming a clear contrast with the parts that had not yet been in contact with the cryogenic liquid.

[0055] (2) The temperature of the cryo-liquid is much lower than the freezing point of the phase change material, so the phase change material freezes rapidly when the photonic crystal assembly comes into contact with the cryo-liquid. The formed ice crystals squeeze out PEGDA and change the spacing and periodic arrangement of the gold nanoparticles, which macroscopically manifests as a distinct structural color in the photonic crystal assembly. As the mold is pushed downwards, the photonic crystal assembly gradually changes color completely and can maintain this structural color below the freezing point. Thus, the photonic crystal indicator tag was successfully fabricated.

[0056] The photonic crystal indicator tag provided in this embodiment has an indicating temperature of -25℃. When the ambient temperature is higher than this temperature, the ice crystals melt into water, which remixes with PEGDA, increasing the gaps between the gold nanoparticles and restoring their periodic arrangement before freezing. Macroscopically, this manifests as the disappearance of the structural color of the photonic crystal indicator tag. At this point, unless it is completely frozen again in the manner of step (1), the structural color cannot be restored. However, in actual use, it is usually difficult to meet the conditions for directional freezing. Therefore, as long as the color of the photonic crystal indicator tag changes, it indicates that the ambient temperature has been or is currently higher than the set freezing point temperature.

[0057] The difference between this embodiment and Embodiment 1 lies in the different photonic crystals, the different compositions of the photonic crystal assemblies, and the different packaging conditions. As can be seen from this embodiment and Embodiment 1, changing the composition of the photonic crystal and the photonic crystal assembly can sensitively control the freezing point temperature and structural color, thereby better adapting to the needs of actual production; and the packaging conditions do not affect the generation, disappearance, and recognition of the structural color.

[0058] Example 3

[0059] The fabrication process of the photonic crystal indicator tag for low-temperature monitoring provided in this embodiment is as follows:

[0060] (1) 100 nm TiO2 particles were uniformly dispersed in a 20% sodium chloride solution (freezing point -10°C), and a certain amount of liquid paraffin was added to form a photonic crystal assembly with a TiO2 colloidal particle mass fraction of 20 wt%. Following the method in Example 2, the photonic crystal assembly was injected into a plastic mold and slowly and vertically pushed into a cryogenic liquid at a temperature of -20°C at a speed of 1 mm / s. The part in contact with the cryogenic liquid would first generate structural color. Since the liquid paraffin would turn into a milky white solid at around -10°C, it would fix the photonic crystal assembly while reducing the saturation of the structural color and adjusting its range to a certain extent. When the ambient temperature was above -10°C, both the ice crystals and paraffin melted and mixed, changing the gaps and arrangement order of the photonic crystal particles, causing the structural color to disappear.

[0061] This embodiment demonstrates that the photonic crystal indicator label of the present invention can fix the shape of the photonic crystal assembly by using wax as a matrix and solidifying the liquid wax at low temperature, without the need for external packaging, thus further simplifying the production process; at the same time, it shows that the saturation of the structural color can be adjusted according to different matrices, further expanding the coverage range of the photonic crystal structural color.

[0062] The embodiments of the present invention have been described in detail above, but these are merely examples for ease of understanding and should not be considered as limiting the scope of the invention. Similarly, anyone skilled in the art can make various possible equivalent changes and substitutions based on the technical solutions and preferred embodiments described in this invention, but all such changes and substitutions should fall within the protection scope of the claims of this invention.

Claims

1. A photonic crystal indicator tag for cryogenic monitoring, characterized by: The photonic crystal indicating label is a composite of photonic crystal particles, a matrix and a phase change material; a large number of photonic crystal particles are regularly arranged in the matrix to form an ordered structure, and the phase change material is filled between the photonic crystal particles and the matrix; the freezing point of the phase change material changes with the proportion of water content, and the change range is-80℃ to-10℃; The photonic crystal indicating label uses the space occupation effect of long-range ordered ice crystals formed by directional freezing to extrude the non-aqueous phase matrix, thereby adjusting the gap and periodic arrangement mode of the photonic crystal particles, and further making the reflection wavelength of the photonic crystal red-shift or blue-shift, so that the color of the label changes; The photonic crystal particles are temperature-responsive photonic crystal particles; The preparation method of the temperature-responsive photonic crystal particle and the phase change material composite comprises the following steps: Adjusting the proportion of the phase change material to regulate the phase change temperature; Mixing the matrix, the photonic crystal particles and the phase change material uniformly to prepare a pre-gel suspension of the photonic crystal particles; and directionally freezing the pre-gel suspension to make the ice crystals directionally arrange and long-range order; The phase change point of the phase change material is the freezing point; The phase change material is at least one of an ionic liquid, an organic solvent, a salt solution and a sugar; The ionic liquid is at least one of 1-ethyl-3-methyl imidazole bis-trifluoromethane sulfonimide salt, triethylmethyl ammonium tetrafluoroborate and bis-trifluoromethane sulfonimide salt ionic liquid; The organic solvent is at least one of glycerol, ethylene glycol, propylene glycol and ethanol; The salt solution is at least one of sodium chloride, magnesium chloride, sodium nitrate, calcium chloride and potassium sulfate; The sugar is at least one of sucrose, fructose, glucose, trehalose and arabinose; The matrix is at least one of a high-molecular organic compound, an oligomer, an oil and a wax; The high-molecular organic compound with fluidity is at least one of polyethylene glycol, polystyrene, polyvinyl chloride, polypropylene amide and polyvinyl pyrrolidone; The oligomer is at least one of polyester resin, epoxy resin, polyurethane acrylate, epoxy acrylate and polyether acrylate; The wax is at least one of paraffin wax, ozokerite, beeswax, Sichuan wax and coconut wax; The particle size of the photonic crystal particles is 30nm to 3000nm, the regularly arranged photonic crystal particles are two-dimensional or three-dimensional structures, and the gap between the photonic crystal particles is 0.1nm to 500nm. The photonic crystal particles are one or any combination of inorganic compounds, metal oxides, metal particles and semiconductors; 2. The photonic crystal indicator tag for cryogenic monitoring according to claim 1, wherein, The inorganic compound is at least one of silicon dioxide, silicon carbide, titanium carbide, zinc sulfide and silver chloride; The metal oxide is at least one of zinc oxide, aluminum oxide, triiron tetroxide and diiron trioxide; The metal particle is at least one of gold, silver, copper, iron, nickel and platinum; The semiconductor is at least one of titanium sesquioxide, titanium dioxide, gallium nitride and gallium arsenide. The preparation method of the photonic crystal particles is at least one of co-precipitation self-assembly, solvent evaporation, sol-gel method, vapor deposition and centrifugal sedimentation.

3. The photonic crystal indicator tag for cryogenic monitoring of claim 1, wherein, ​ 4. The photonic crystal indicator tag for cryogenic monitoring according to any one of claims 1-3, wherein, Any of the photonic crystal particles described can be used in photonic crystal tag preparation, vaccine temperature monitoring, ex vivo organ temperature monitoring, frozen food temperature monitoring, and pharmaceutical storage temperature monitoring.