Infrared metasurface element for heated tobacco device

Abstract

An infrared metasurface element for a heated tobacco device, the infrared metasurface element comprising: a substrate (1), a dielectric layer (2) and an infrared-selective metasurface layer (3), the dielectric layer (2) being provided on the surface of the substrate (1), the infrared-selective metasurface layer (3) being arranged on the dielectric layer (2), the infrared-selective metasurface layer (3) being provided with a spectrally selective infrared radiation metasurface, and a micron-nano-scale periodic or non-periodic structure being provided on the spectrally selective infrared radiation metasurface. On the basis of absorption spectrums of tobacco sticks, the present application constructs the layout and the structure of a basic micro-nano structure unit having a spectrally selective infrared radiation metasurface, so as to obtain the spectrally selective infrared radiation metasurface by means of simulation and fabricate same, so that infrared radiation spectrums of heating elements comprising the infrared radiation metasurfaces match absorption bands of tobacco sticks.

Description

Infrared metasurface components for cigarette heating devices

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on February 18, 2024, with application number 202410180986.9, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of smoking article heating elements, for example, to an infrared metasurface element for smoking articles for heating cigarettes. Background Art

[0003] In recent years, various heating methods have been adopted in various heated tobacco devices. These devices use heated tobacco (HNB) as the cartridge, which has a flavor similar to traditional tobacco. Furthermore, since the heating temperature does not exceed 300°C, the release of harmful substances can be reduced by 90% compared to the combustion process of traditional cigarettes. Therefore, HNB cigarettes are more easily accepted and converted by smokers. Most heated tobacco devices, which use heat conduction heating, suffer from problems such as slow heating rates and uneven heating (large temperature gradients within the cigarette), which significantly affect the smoking experience. Compared with heat conduction heating, infrared heating can increase the heating rate while uniformly heating the cigarette, allowing smokers to release aerosols evenly during the puff, improving the smoking experience. Current infrared heating research primarily uses high-emissivity ceramics, graphite, and electrothermal films to achieve radiant heating. For example, patent CN202010499974.4 uses an insulator tube coated with electrothermal film to achieve infrared heating.

[0004] However, while the infrared emitting materials used in currently available infrared heating devices have high emissivity in the infrared band, the spectral emissivity of these infrared materials is generally high across a broad band. Infrared radiation in some bands cannot be effectively absorbed by cigarettes, resulting in a certain degree of infrared radiation waste. Therefore, in order to achieve efficient infrared heating of cigarettes, it is necessary to provide an infrared heating element whose infrared spectral emissivity matches the infrared absorption characteristics of cigarettes, thereby more effectively improving the energy efficiency of infrared radiation. Summary of the Invention

[0005] The present application provides an infrared metasurface element for cigarette heating devices, which solves the problem that the infrared heating elements in the related art infrared heating devices cannot fully utilize the infrared radiation, which easily causes energy waste. It can improve the matching level between the infrared spectral emissivity and the infrared absorption characteristics of cigarettes, and enhance the infrared radiation energy efficiency of the infrared heating devices.

[0006] To achieve the following objectives, this application provides the following technical solutions:

[0007] An infrared metasurface element for a cigarette heating device, comprising: a substrate, a dielectric layer, and an infrared selective metasurface layer;

[0008] The dielectric layer is provided on the surface of the substrate, and the infrared selective super surface layer is provided above the dielectric layer;

[0009] The infrared selective metasurface layer is provided with a spectrally selective infrared radiation metasurface, and the spectrally selective infrared radiation metasurface has a periodic or non-periodic structure of micrometer to nanometer scale;

[0010] The layout and structure of the basic micro-nanostructural units of the spectrally selective infrared radiation metasurface are constructed according to the absorption spectrum of cigarettes, and then the spectrally selective infrared radiation metasurface is obtained and prepared through simulation, so that the infrared radiation spectrum of the heating element based on the prepared infrared radiation metasurface matches the absorption band of cigarettes.

[0011] In some embodiments, the substrate is made of metal or non-metal.

[0012] In some embodiments, the substrate is made of aluminum, aluminum alloy, stainless steel, iron, titanium, titanium alloy, ordinary glass, quartz, and alumina.

[0013] In some embodiments, the substrate is in the shape of a plane or a closed curved surface.

[0014] In some embodiments, the periodic or non-periodic structures are micron-nanometer scale protrusions, depressions, or grooves.

[0015] In some embodiments, the height of the basic micro-nano structure unit ranges from 20 nm to 5000 nm, the length ranges from 20 nm to 10000 nm, and the center distance between adjacent basic micro-nano structure units ranges from 20 nm to 10000 nm.

[0016] In some embodiments, the basic micro-nano structural unit is composed of one or more of metals, conductive metal oxide materials, or non-oxide materials whose real part of dielectric constant is negative in the optical frequency band.

[0017] In some embodiments, the metal materials constituting the basic micro-nanostructure units include: gold, silver, aluminum, and titanium;

[0018] The conductive metal oxide material includes: indium tin oxide, aluminum-doped zinc oxide, antimony-doped tin oxide and non-stoichiometric oxides;

[0019] The non-oxide materials include carbon, titanium nitride and titanium carbide.

[0020] In some embodiments, the spectrally selective infrared radiation metasurface is provided with an oxide protective layer with a thickness of 10-200 nm.

[0021] In some embodiments, the dielectric layer is an oxide layer of the substrate itself, or an insulating metal or non-metal oxide layer deposited on the surface of the substrate;

[0022] The insulating metal or non-metal oxide layer includes: SiO2, Al2O3, MgO, TiO2, ZrO2, HfO2 or Y2O3.

[0023] The present application provides an infrared metasurface element for use in cigarette heating devices. A dielectric layer and an infrared-selective metasurface layer are formed on the substrate of the heating element. The infrared-selective metasurface layer has a spectrally selective infrared radiation metasurface. The metasurface uses a micro-nanoscale structure to regulate infrared emission characteristics to match the infrared absorption characteristics of the heated cigarette, thereby maximizing the conversion of Joule heat generated by electrical energy into infrared radiation to heat the cigarette. This significantly reduces the proportion of ineffective infrared radiation, making the device more energy-efficient. This solves the problem of infrared heating elements in related-art infrared heating devices, which suffer from insufficient infrared radiation and easily lead to energy waste. The invention can improve the matching level between the infrared spectral emissivity and the infrared absorption characteristics of the cigarette, thereby enhancing the infrared radiation energy efficiency of the infrared heating device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments.

[0025] FIG1 is a schematic structural diagram of an infrared heating element for a cigarette heating smoking device provided by the present application;

[0026] FIG2 is a top view of the selective metasurface provided in Example 1 of the present application;

[0027] FIG3 is a spectral radiance diagram of the selective metasurface prepared in Example 1 of the present application;

[0028] FIG4 is a spectral radiance diagram of the selective metasurface prepared in Example 2 of the present application;

[0029] FIG5 is a top view of the selective metasurface provided in Example 3 of the present application;

[0030] FIG6 is a spectral radiance diagram of the selective metasurface prepared in Example 3 of the present application;

[0031] FIG7 is a top view of the selective metasurface provided in Example 4 of the present application;

[0032] Figure 8 is a spectral radiance diagram of the selective metasurface prepared as provided in Example 4 of the present application. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to better understand the solutions of the embodiments of the present application, the embodiments of the present application are further described in detail below in conjunction with the accompanying drawings and implementation methods.

[0034] In response to the problem of infrared radiation energy efficiency of the heating elements of infrared heating smoking devices in related technologies, the present application provides an infrared metasurface element for cigarette heating smoking devices, which solves the problem that the infrared radiation of the infrared heating elements in infrared heating smoking devices in related technologies cannot be fully utilized, which easily causes energy waste. It can improve the matching level between the infrared spectral emissivity and the infrared absorption characteristics of cigarettes, and enhance the infrared radiation energy efficiency of infrared heating smoking devices.

[0035] As shown in Figure 1, an infrared metasurface element for a cigarette heating device comprises: a substrate 1, a dielectric layer 2, and an infrared selective metasurface layer 3. The dielectric layer 2 is provided on the surface of the substrate 1, and the infrared selective metasurface layer 3 is provided above the dielectric layer 2. The infrared selective metasurface layer is provided with a spectrally selective infrared radiation metasurface, and the spectrally selective infrared radiation metasurface has a periodic or non-periodic structure at the micrometer to nanometer scale. The layout and structure of the basic micro-nanostructural units of the spectrally selective infrared radiation metasurface are constructed based on the absorption spectrum of cigarettes, and then the spectrally selective infrared radiation metasurface is obtained and prepared through simulation, so that the infrared radiation spectrum of the heating element based on the prepared infrared radiation metasurface matches the absorption band of cigarettes.

[0036] Specifically, based on the measured cigarette absorption spectrum, the infrared metasurface's material, substrate, and geometric structure are selected and designed through finite-difference numerical simulation. The metasurface's infrared radiation spectrum is then calculated and compared with the cigarette's absorption spectrum to adjust and optimize the material selection and geometric structure. Ultimately, a metasurface design is achieved that matches the two main absorption bands of cigarettes (2.5-3.5μm and 6-10μm). Based on this, a suitable fabrication process is selected based on the type of metasurface to achieve metasurface fabrication. Finally, the metasurface's heating element, electrical heating element, thermal insulation element, battery, and object are assembled to create a smoking device. This method, which utilizes a micro- and nanoscale metasurface to manipulate infrared emission characteristics to match the infrared absorption characteristics of the heated cigarette, maximizes the conversion of Joule heat generated by electrical energy into infrared radiation to heat the cigarette, significantly reducing the proportion of ineffective infrared radiation and making the smoking device more energy-efficient.

[0037] In practical applications, the spectrally selective infrared radiation metasurface is located on the inner wall of the heating tube and serves as a heating element.

[0038] Furthermore, the infrared spectral emissivity (or absorptivity) of the infrared selective metasurface matches the absorption spectrum of the aerosol generating material (cigarette) in the infrared band.

[0039] Furthermore, the substrate of the infrared selective metasurface is a metal or non-metal substrate, including aluminum, aluminum alloy, stainless steel, iron, titanium, titanium alloy, ordinary glass, quartz (SiO2), corundum (Al2O3), etc., and the shape of these substrates can be flat or closed curved surface (such as tubular), and there is a dielectric layer with a thickness of 0-10000nm on its surface, which can be the oxide layer of the metal substrate itself, or an insulating metal or non-metal oxide layer deposited on the surface.

[0040] Furthermore, the insulating metal or non-metal oxide layer can be an oxide of an insulating metal or non-metal such as SiO2, Al2O3, MgO, TiO2, ZrO2, HfO2, or Y2O3.

[0041] Furthermore, infrared selective metasurfaces have micron-nanoscale periodic or non-periodic structures, and the basic units of these periodic structures are micron-nanoscale protrusions, depressions or grooves.

[0042] Furthermore, the height (or depth) of the basic micro-nanostructure units in the infrared selective metasurface ranges from 20nm to 5000nm, the length (and width) ranges from 20nm to 10000nm, and the center distance between adjacent basic micro-nanostructure units is 20nm to 10000nm.

[0043] Furthermore, the chemical composition of the basic micro-nano structural unit is a composite of one or more of metals, conductive metal oxides or metal non-oxide materials whose real part of dielectric constant is negative in the optical frequency band.

[0044] Furthermore, the metal materials that constitute the basic micro-nano structural units of the infrared selective metasurface can be metal materials such as gold, silver, aluminum, and titanium. The conductive metal oxide materials can be indium tin oxide (ITO, In2O3:Sn), aluminum-doped zinc oxide (AZO, ZnO:Al), antimony-doped tin oxide (ATO, SnO2:Sb), non-stoichiometric oxides (such as TiOx, SnOx, etc.) and other conductive metal oxides. The non-oxide materials can be compound conductive materials such as carbon (C), titanium nitride (TiN), and titanium carbide (TiC).

[0045] Furthermore, metasurfaces can be prepared through a variety of processes such as magnetron sputtering, electron beam evaporation, nanoimprinting combined with photolithography.

[0046] Furthermore, the infrared-selective metasurface can have a protective oxide layer with a thickness of 10 to 200 nm. This oxide layer can be produced through processes such as magnetron sputtering, pulsed laser deposition, and sol-gel. This protective layer primarily prevents oxidation and enhances the stability of the metasurface after repeated use, enabling the resulting heater to operate at temperatures up to 500°C.

[0047] Furthermore, the aforementioned metasurface can be used to create infrared instant-heating smoking devices. For example, when the metasurface is applied to the inner wall of a circular tube (e.g., a metal tube), it can be used directly as a heating tube. A resistive wire mesh or electrothermal film coating can be applied to the outside to form a heating tube. This can then be covered with a thermal insulation layer, integrated with a control circuit and film, and then added to an outer box to create an infrared heating smoking device.

[0048] Example 1:

[0049] The infrared metasurface uses an aluminum plate with a thickness of 200μm and a 0.5μm Al2O3 layer on its surface. An In2O3:Sn (ITO) array is grown on the substrate surface, as shown in Figures 1 and 2. The length, width, and height of the ITO unit are 200nm, 900nm, and 100nm, respectively. The infrared metasurface is fabricated using magnetron sputtering combined with electron beam etching and other processes. Testing of its infrared spectrum revealed that its emissivity peak is at 3.15μm, as shown in Figure 3, and its half-height width is 900nm, which coincides with the absorption peaks of groups such as hydroxyl groups in tobacco, enabling efficient infrared heating of tobacco.

[0050] Example 2:

[0051] The substrate used in the infrared metasurface of this embodiment is a stainless steel plate with a thickness of 100 μm, and a 0.5 μm SiO2 layer is provided on the surface of the stainless steel plate. A ZnO:Al (AZO) array is grown on the surface of the substrate, wherein the length, width and height of the AZO unit are 400 nm, 700 nm and 100 nm, respectively. The infrared metasurface is made by magnetron sputtering combined with processes such as electron beam etching. By testing its infrared spectrum, it was found that it has two emissivities, which are near 2.85 μm and 5.5 μm, as shown in Figure 4. The radiation peak at 5.5 μm has a large half-height width, which coincides with the absorption peaks of groups such as hydroxyl groups in tobacco, and can achieve efficient infrared heating of tobacco.

[0052] Example 3:

[0053] The substrate used in the infrared metasurface of this embodiment is an aluminum alloy plate with a thickness of 250μm, and there is a 0.5μm Al2O3 layer on the surface of the aluminum alloy plate. A SnO2:Sb (ATO) array is grown on the surface of the substrate, wherein the length, width and height of the ATO unit are 1414nm, 1414nm and 100nm respectively, and its arrangement is shown in Figure 5. The infrared metasurface is made by magnetron sputtering combined with electron beam etching and other processes. By testing its infrared spectrum, it was found that it has two emissivities, which are near 2.85μm and 5.5μm respectively, as shown in Figure 6. The radiation peak of 5.5μm has a large half-height width, which coincides with the absorption peak of groups such as hydroxyl groups in tobacco, and can achieve efficient infrared heating of tobacco.

[0054] The above-mentioned metasurface was cut and rolled into a tube with a length of 4 cm and an inner diameter of 5.6 mm. The metasurface was inside the tube, and then wrapped with a PI insulation layer and a resistance wire mesh (resistance of 2.0Ω) on the outside to make a heating element.

[0055] Under a constant voltage of 7V, the metasurface can heat simulated tobacco to 250°C within 25 seconds, while a smooth aluminum tube without a metasurface on the inner wall takes 29 seconds to heat to the same temperature under the same input voltage, indicating that infrared radiation effectively increases the heating rate.

[0056] Example 4:

[0057] The substrate used in the infrared metasurface of this embodiment is an aluminum alloy plate with a thickness of 250μm, and a 0.5μm SiO2 layer is provided on the surface of the aluminum alloy plate. An ITO array is grown on the surface of the substrate, wherein the length, width and height of the ATO unit are 200nm, 1000nm and 100nm respectively, and the arrangement is shown in Figure 7. The infrared metasurface is made by magnetron sputtering combined with electron beam etching and other processes. By testing its infrared spectrum, it was found that it has two emissivities, which are near 3.2μm and 5.1μm respectively. As shown in Figure 8, both radiation peaks have a large half-height width, which coincides with the main infrared absorption band in tobacco, and can achieve efficient infrared heating of tobacco.

[0058] The above-mentioned metasurface was cut and rolled into a tube with a length of 4 cm and an inner diameter of 5.6 mm. The metasurface was inside the tube, and then wrapped with a PI insulation layer and a resistance wire mesh (resistance of 1.8Ω) on the outside to make a heating element.

[0059] Under a constant voltage of 7V, the metasurface can heat simulated tobacco to 250°C within 22 seconds, while a smooth aluminum sheet without a metasurface on the inner wall takes 27 seconds to heat to the same temperature under the same input voltage, indicating that infrared radiation effectively increases the heating rate.

[0060] Example 5:

[0061] The substrate used in the infrared metasurface of this embodiment is a titanium plate with a thickness of 100 μm, and there is 0.5 μm of TiO2 on the surface of the aluminum plate. A SnO2:F (FTO) array is grown on the surface of the substrate, wherein the length, width and height of the FTO unit are 300 nm, 600 nm and 100 nm respectively. The infrared metasurface is made by magnetron sputtering combined with electron beam etching and other processes. By testing its infrared spectrum, it is found that its emissivity peak is at 3.35 μm, and the half-height width can reach 1600 nm, which is consistent with the absorption peak of groups such as hydroxyl groups in tobacco, and can achieve efficient infrared heating of tobacco.

[0062] Example 6:

[0063] The substrate used in the infrared metasurface of this embodiment is a titanium alloy plate with a thickness of 300μm, and there is 0.5μm of Al2O3 on the surface of the titanium alloy plate. An In2O3:Sn (ITO) array is grown on the surface of the substrate, wherein the length, width and height of the ITO unit are 400nm, 700nm and 100nm respectively. The infrared metasurface is made by magnetron sputtering combined with electron beam etching and other processes. By testing its infrared spectrum, it is found that its emissivity peak is at 4.18μm, as shown in Figure 3, and its half-height width can reach 1900nm, which can cover the main absorption peak of cigarettes on the short-wave side, and can achieve efficient infrared heating of tobacco.

[0064] As can be seen, the present application provides an infrared metasurface element for cigarette heating devices. A dielectric layer and an infrared-selective metasurface layer are formed on the substrate of the heating element. The infrared-selective metasurface layer has a spectrally selective infrared radiation metasurface. The metasurface uses a micro-nanoscale structure to control infrared emission characteristics to match the infrared absorption characteristics of the heated cigarette, thereby maximizing the conversion of Joule heat generated by electrical energy into infrared radiation to heat the cigarette. This significantly reduces the proportion of ineffective infrared radiation, making the smoking device more energy-efficient. This can solve the problem of infrared heating elements in related infrared heating devices, which suffer from insufficient infrared radiation utilization and easily lead to energy waste. It can improve the matching level between the infrared spectral emissivity and the infrared absorption characteristics of the cigarette, thereby enhancing the infrared radiation energy efficiency of the infrared heating device.

Claims

1. An infrared metasurface element for a cigarette heating device, comprising: substrate, dielectric layer, and infrared-selective metasurface layer; The dielectric layer is provided on the surface of the substrate, and the infrared selective super surface layer is provided above the dielectric layer; The infrared selective metasurface layer is provided with a spectrally selective infrared radiation metasurface, and the spectrally selective infrared radiation metasurface has a periodic or non-periodic structure of micrometer to nanometer scale; The layout and structure of the basic micro-nanostructural units of the spectrally selective infrared radiation metasurface are constructed according to the absorption spectrum of cigarettes, and then the spectrally selective infrared radiation metasurface is obtained and prepared through simulation, so that the infrared radiation spectrum of the heating element based on the prepared infrared radiation metasurface matches the absorption band of cigarettes.

2. The infrared metasurface element for a cigarette heating device according to claim 1, wherein: The substrate is made of metal or non-metal.

3. The infrared metasurface element for a cigarette heating device according to claim 2, wherein: The materials of the substrate include: aluminum, aluminum alloy, stainless steel, iron, titanium, titanium alloy, ordinary glass, quartz and alumina.

4. The infrared metasurface element for a cigarette heating device according to claim 3, wherein: The substrate is in the shape of a plane or a closed curved surface.

5. The infrared metasurface element for a cigarette heating device according to claim 4, wherein: The periodic or non-periodic structure is a micron-nanometer scale protrusion, depression or groove.

6. The infrared metasurface element for a cigarette heating device according to claim 5, wherein: The height of the basic micro-nano structure unit ranges from 20nm to 5000nm, the length ranges from 20nm to 10000nm, and the center distance between adjacent basic micro-nano structure units ranges from 20nm to 10000nm.

7. The infrared metasurface element for a cigarette heating device according to claim 6, wherein: The basic micro-nano structural unit is composed of one or more of a metal material, a conductive metal oxide material or a non-oxide material whose real part of the dielectric constant is negative in the optical frequency band.

8. The infrared metasurface element for a cigarette heating device according to claim 7, wherein: The metal materials constituting the basic micro-nano structural unit include: gold, silver, aluminum and titanium; The conductive metal oxide material includes: indium tin oxide, aluminum-doped zinc oxide, antimony-doped tin oxide and non-stoichiometric oxides; The non-oxide materials include carbon, titanium nitride and titanium carbide.

9. The infrared metasurface element for a cigarette heating device according to claim 8, wherein: The spectrally selective infrared radiation super surface is provided with an oxide protective layer with a thickness of 10-200 nm.

10. The infrared metasurface element for a cigarette heating device according to any one of claims 1 to 9, wherein: The dielectric layer is an oxide layer of the substrate itself, or an insulating metal or non-metal oxide layer deposited on the surface of the substrate; The insulating metal or non-metal oxide layer includes: SiO2, Al2O3, MgO, TiO2, ZrO2, HfO2 or Y2O3.

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