A hydrogen sensor, a planar chiral structure and its preparation method

Abstract

This invention discloses a hydrogen sensor, a planar chiral structure, and its fabrication method. The planar chiral structure includes: a substrate layer; a Cr layer disposed on the substrate layer; a surface plasmon material layer covering the Cr layer; and a Pd layer covering the surface plasmon material layer. The planar chiral structure is windmill-shaped; the ratio of the distance L between the two diagonals to the distance W between the two interior angles is (2~4):1. The planar chiral structure provided by this invention amplifies the signal intensity of a single planar chiral structure to a level suitable for direct detection applications; it also allows for the integration of multiple planar chiral structures into an array for integrated applications. The fabrication method is simple and easy to implement, and can be directly fabricated on the substrate layer, enabling large-scale production. The hydrogen sensor detection unit is as small as the submicron level and can be used for efficient detection of hydrogen concentration, leakage, and content in energy, industry, transportation, security, and medical fields.

Description

Technical Field

[0001] This invention relates to a hydrogen sensor, a planar chiral structure and its preparation method, belonging to the technical field of chiral optical hydrogen sensor. Background Technology

[0002] Highly sensitive hydrogen sensors are crucial for the safe handling, transportation, and storage of hydrogen. Surface plasmon resonance (SPR) sensors are promising next-generation sensors due to their ability to avoid sparks, provide remote, contactless data reading, and miniaturize devices to the single-particle scale while remaining non-invasive. Among these, chiral optical hydrogen sensors, by coating Pd onto the surface of chiral surface plasmon resonance materials, sensitively capture the change in dielectric properties of Pd before and after hydrogen absorption, thus exhibiting high sensitivity. However, current methods for preparing chiral surface plasmon resonance materials mainly fall into two categories: aqueous phase preparation of three-dimensional chiral materials and preparation of periodic arrays using methods such as electron beam etching or photolithography. The former relies on bulk detection in a liquid phase, while the latter's chiral signal originates from resonance caused by the periodic array structure; both methods have limitations in device miniaturization. Summary of the Invention

[0003] Objective: In order to overcome the shortcomings of the prior art, the present invention provides a hydrogen sensor, a planar chiral structure and a method for preparing the same.

[0004] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0005] In a first aspect, a planar chiral structure is provided, comprising:

[0006] basal layer;

[0007] The Cr layer is placed on the substrate layer;

[0008] A surface plasmon material layer covers the Cr layer;

[0009] A Pd layer is applied over a surface plasmon material layer.

[0010] The planar chiral structure is a windmill shape composed of four identical right-angled triangles; the distance between the first vertices of two opposite right-angled triangles is called the distance between the two opposite angles L, the distance between the second vertices of two opposite right-angled triangles is called the distance between the two interior angles W, and the ratio of L to W is (2~4):1.

[0011] The planar chiral structure provided by this invention does not rely on the macroscopic response caused by the resonance of a periodic array for its chiral optical response. A single planar chiral structure can generate a chiral optical response on its own. Furthermore, its signal strength can be directly detected and applied. At the same time, the planar chiral structures provided by this invention can also be arranged into an array to realize detection applications in an integrated form, and their chiral optical response also originates from each planar chiral structure itself.

[0012] In some embodiments, the Cr layer has a thickness of 1-3 nm; the surface plasmon material layer has a thickness of 23-27 nm; and the Pd layer has a thickness of 1-10 nm. Pd layer thicknesses in the range of 1-10 nm exhibit strong responsiveness to hydrogen.

[0013] In some embodiments, the distance L between the two diagonals of the planar chiral structure is 480 nm to 800 nm. The size of the planar chiral structure is determined by the distance L between the two diagonals and the distance W between the two interior angles. Adjusting the size of the planar chiral structure can adapt to detection applications in different wavelength bands.

[0014] In some embodiments, the surface plasmon material is selected from at least one of Al or Au, and changing the surface plasmon material can adapt to different working environments.

[0015] In a second aspect, a method for preparing the planar chiral structure described in the first aspect is provided, comprising:

[0016] S1. Spin-coat polymethyl methacrylate (PMMA) onto the substrate surface after oxygen plasma cleaning; bake the spin-coated PMMA substrate.

[0017] S2. Etch the polymethyl methacrylate on the surface of the baked substrate according to the preset pattern; immerse the etched substrate in the developer first, and then in the fixer; after immersion, take out the substrate, rinse it with ultrapure water, and blow it dry to obtain a substrate with a polymethyl methacrylate etched pattern on the surface.

[0018] S3. First, deposit a Cr layer on the substrate layer with a polymethyl methacrylate etching pattern, then deposit a surface plasmon material layer. Immerse the substrate layer after depositing the surface plasmon material layer in acetone and sonicate it. Rinse the ultrasonically treated substrate layer with ethanol and blow it dry to obtain a substrate layer with a surface plasmon material layer.

[0019] S4. A Pd layer is deposited on a substrate layer with a surface plasmon material layer to obtain a planar chiral structure.

[0020] The preparation method provided by this invention is simple and easy to implement, and can quickly and on a large scale produce planar chiral structures for application.

[0021] In some embodiments, the baking temperature in S1 is 135°C to 170°C, and the baking time is 3 to 5 minutes.

[0022] In some embodiments, the etching exposure dose set in S2 is 102.9~123.5 μC / cm. 2 .

[0023] In some embodiments, in S3, a Cr layer is deposited at a rate of 0.05 Å / s to 0.15 Å / s; and a surface plasmon material layer is deposited at a rate of 1 Å / s to 2 Å / s.

[0024] In S4, a Pd layer is deposited at a rate of 0.1 Å / s to 0.3 Å / s.

[0025] Thirdly, a hydrogen sensor is provided, comprising at least one of the aforementioned planar chiral structures.

[0026] In some embodiments, there are two or more planar chiral structures, adjacent planar chiral structures are spaced at least 5 μm apart, and all planar chiral structures have different dimensions.

[0027] The hydrogen sensor provided by this invention derives its chiral optical response from a single planar chiral structure itself. When two or more planar chiral structures exist, their adjacent planar chiral structures are spaced at least 5 μm apart. At this distance, the coupling resonance between the planar chiral structures completely disappears, and each planar chiral structure has a different size, resulting in different detection results for the same hydrogen concentration from each planar chiral structure.

[0028] A hydrogen sensor with only a single planar chiral structure can be fabricated, relying on the wavelength shift (i.e., zero-point shift) corresponding to the zero point of the spectral signal intensity in the circular differential scattering (CDS) spectrum before and after hydrogen absorption. Alternatively, a hydrogen sensor composed of an integrated array of planar chiral structures of different sizes can be fabricated. First, the zero-point shifts detected by each planar chiral structure under different hydrogen concentration conditions are statistically analyzed to generate color-differentiated thermograms. Since the zero-point shift detection results for the same hydrogen concentration differ for each planar chiral structure, the colors displayed on the generated thermograms are also different. Based on this, the thermograms generated from the detection results of all planar chiral structures are aggregated to construct a thermometric comparison map. By comparing the color of the actual hydrogen-generated thermogram with the thermometric comparison map, the actual detected hydrogen concentration can be determined. Compared to a planar chiral structure array, a hydrogen sensor based on a single planar chiral structure is smaller; compared to a single planar chiral structure, a hydrogen sensor based on a planar chiral structure array has higher detection sensitivity.

[0029] Beneficial effects:

[0030] 1. The planar chiral structure provided by this invention has a chiral optical response that originates from the individual planar chiral structure itself, without relying on the macroscopic chiral optical response caused by periodic array resonance; it amplifies the signal intensity generated by a single planar chiral structure to a level that can be directly detected; and it can also integrate multiple planar chiral structures into an array for detection applications.

[0031] 2. The hydrogen sensor provided by this invention is not limited by liquid phase detection and periodic arrays, and the overall size of the device can be kept close to the size of a single planar chiral structure or an array of planar chiral structures; it can be fabricated as a sensor with a single planar chiral structure to meet the miniaturization requirements, or as a sensor integrated with a planar chiral structure array to meet the high sensitivity requirements;

[0032] 3. The preparation method provided by this invention is simple and easy to implement, and the planar chiral structure has better stability. It can be prepared directly on the substrate layer and can be mass-produced. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a planar chiral structure according to an embodiment of the present invention;

[0034] Figure 2 This is a SEM image of the planar chiral structure without a Pd layer in Embodiment 2 of the present invention;

[0035] Figure 3 This is a CDS spectral simulation result of the hydrogen sensor before and after hydrogen absorption in Embodiment 4 of the present invention;

[0036] Figure 4 This is a simulation result of the CDS spectrum of the hydrogen sensor before and after hydrogen absorption in Embodiment 4 of the present invention after signal conversion;

[0037] Figure 5 This is a SEM image of the hydrogen sensor after Pd layer deposition in Embodiment 5 of the present invention.

[0038] Figure 6 This is a CDS spectral detection result diagram of the hydrogen sensor before and after hydrogen absorption in Embodiment 5 of the present invention;

[0039] Figure 7 This is a graph showing the detection results of the CDS spectra of the hydrogen sensor before and after hydrogen absorption in Embodiment 5 of the present invention after signal conversion;

[0040] Figure 8 This is a CDS spectrum simulation result of the hydrogen sensor in Embodiment 5 of the present invention responding to hydrogen concentration after hydrogen absorption;

[0041] Figure 9 This is a comparison chart of the CDS spectral simulation results of two hydrogen sensors after hydrogen absorption in Embodiment 15 of the present invention;

[0042] Figure 10 This is a statistical diagram showing the simulated zero-point displacement of the hydrogen sensor before and after hydrogen absorption in Embodiment 16 of the present invention.

[0043] Figure 11 This is a thermodynamic comparison diagram generated based on the statistical results of zero-point displacement simulation in Embodiment 16 of the present invention. Detailed Implementation

[0044] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0045] The present invention will be further described below with reference to specific embodiments.

[0046] like Figure 1 As shown, the planar chiral structure is a windmill shape composed of four identical right-angled triangles; the distance between the first vertices of two opposite right-angled triangles is called the distance between the two opposite angles L, and the distance between the second vertices of two opposite right-angled triangles is called the distance between the two interior angles W, and the ratio of L to W is (2~4):1.

[0047] Since the Pd layer produces PdH after absorbing hydrogen, the higher the hydrogen concentration, the more PdH is produced, and the higher the volume ratio of PdH in the Pd layer. Therefore, in the theoretical calculations of all embodiments, the change in hydrogen concentration is simulated by adjusting the volume ratio of PdH in the Pd layer.

[0048] Example 1: Oxygen plasma cleaning was performed on the surface of a silicon wafer substrate with an oxide layer thickness of 180 nm. The power was set to 120 W for 5 min. Polymethyl methacrylate (PMMA) was then spin-coated onto the silicon wafer at a spin speed of 3000 rpm and an acceleration of 800 rpm / s for 30 s. The spin-coated silicon wafer was then placed on a hot plate and baked at 150°C for 4 min before being removed. The PMMA surface of the baked silicon wafer was etched using a scanning electron microscope electron beam etching system according to a preset pattern. The preset pattern was a windmill pattern with a distance L of 640 nm between the two diagonals and a distance W of 200 nm between the two inner corners. The exposure dose was set to... After etching, the silicon wafer is first immersed in the developer for 15 seconds, then removed and immersed in the fixer for 30 seconds. After immersion, the silicon wafer is removed, rinsed with ultrapure water, and dried to obtain a silicon wafer with polymethyl methacrylate etched patterns on its surface.

[0049] Using a thermal evaporation coating machine Under vacuum, a Cr layer was first deposited on the surface of a silicon wafer with a polymethyl methacrylate etched pattern at a speed of 0.05 Å / s, followed by an Al layer at a speed of 1.0 Å / s. The silicon wafer with the Al layer deposited was then immersed in acetone for 10 min and ultrasonically treated to remove the ester. The ultrasonically treated silicon wafer was then rinsed with ethanol and dried to obtain a sample with an Al layer.

[0050] Finally, a Pd layer was deposited on a silicon wafer with an Al layer at a rate of 0.2 Å / s to obtain a planar chiral structure. The distance L between the two diagonals of the planar chiral structure is 640 nm, the distance W between the two interior angles is 200 nm, the thickness of the Cr layer is 1 nm, the thickness of the Al layer is 23 nm, and the thickness of the Pd layer is 5 nm.

[0051] Example 2: Oxygen plasma cleaning was performed on the surface of a silicon wafer substrate with an oxide layer thickness of 180 nm. The power was set to 120 W for 5 min. Polymethyl methacrylate (PMMA) and solvent were mixed at a volume ratio of 2:1. The mixture was then dropped onto the silicon wafer and spin-coated at a speed of 2000 rpm and an acceleration of 800 rpm / s for 30 s. The spin-coated silicon wafer was then placed on a hot plate and baked at 135°C for 5 min before being removed. The PMMA on the baked silicon wafer surface was etched according to a preset pattern using a scanning electron microscope electron beam etching system. The preset pattern was a windmill pattern with a distance L of 800 nm between the two diagonals and a distance W of 400 nm between the two inner corners. The exposure dose was set to... After etching, the silicon wafer is first immersed in the developer for 10 seconds, then removed and immersed in the fixer for 30 seconds. After immersion, the silicon wafer is removed, rinsed with ultrapure water, and dried to obtain a silicon wafer with polymethyl methacrylate etched patterns on its surface.

[0052] Using a thermal evaporation coating machine Under vacuum, a Cr layer was first deposited on the surface of a silicon wafer with a polymethyl methacrylate (PMMA) etched pattern at a speed of 0.1 Å / s, followed by an Al layer at a speed of 1.5 Å / s. The silicon wafer with the Al layer deposited was then immersed in acetone for 10 min and ultrasonically treated to remove the acetone. The ultrasonically treated silicon wafer was then rinsed with ethanol and dried to obtain a sample with an Al layer. SEM images are shown below. Figure 2 .

[0053] Finally, a Pd layer was deposited on a silicon wafer with an Al layer at a rate of 0.1 Å / s to obtain a planar chiral structure. The distance L between the two diagonals of the planar chiral structure is 800 nm, the distance W between the two interior angles is 400 nm, the thickness of the Cr layer is 2 nm, the thickness of the Al layer is 25 nm, and the thickness of the Pd layer is 1 nm.

[0054] Example 3: Oxygen plasma cleaning was performed on the surface of a silicon wafer substrate with an oxide layer thickness of 180 nm. The power was set to 120 W for 5 min. Polymethyl methacrylate (PMMA) and solvent were mixed at a volume ratio of 3:1. The mixture was then dropped onto the silicon wafer and spin-coated at a speed of 4000 rpm and an acceleration of 800 rpm / s for 30 s. The spin-coated silicon wafer was then placed on a hot plate and baked at 170°C for 3 min before being removed. The PMMA on the baked silicon wafer surface was etched according to a preset pattern using a scanning electron microscope electron beam etching system. The preset pattern was a windmill pattern with a distance L of 480 nm between two diagonals and a distance W of 120 nm between two inner corners. The exposure dose was set to... After etching, the silicon wafer is first immersed in the developer for 15 seconds, then removed and immersed in the fixer for 30 seconds. After immersion, the silicon wafer is removed, rinsed with ultrapure water, and dried to obtain a silicon wafer with polymethyl methacrylate etched patterns on its surface.

[0055] Using a thermal evaporation coating machine Under vacuum, a Cr layer was first deposited on the surface of a silicon wafer with a polymethyl methacrylate (PMMA) etched pattern at a speed of 0.15 Å / s, followed by an Au layer at a speed of 2.0 Å / s. The silicon wafer with the Au layer deposited was then immersed in acetone for 10 min and ultrasonically treated to remove the ester. The ultrasonically treated silicon wafer was then rinsed with ethanol and dried to obtain a sample with an Au layer.

[0056] Finally, a Pd layer was deposited on a silicon wafer with an Au layer at a rate of 0.3 Å / s to obtain a planar chiral structure. The distance L between the two diagonals of the planar chiral structure is 480 nm, the distance W between the two interior angles is 120 nm, the thickness of the Cr layer is 3 nm, the thickness of the Al layer is 27 nm, and the thickness of the Pd layer is 10 nm.

[0057] Example 4: A single planar chiral structure is used to simulate a hydrogen sensor. The distance L between the two diagonals of the planar chiral structure is 640 nm, the distance W between the two inner angles is 200 nm, the thickness of the Cr layer is 2 nm, the thickness of the Au layer is 25 nm, and the thickness of the Pd layer is 5 nm.

[0058] refer to Figure 3 The wavelengths corresponding to the zero-intensity CDS spectra before and after hydrogen absorption in the simulated Pd layer were calculated theoretically to be approximately 744 nm before hydrogen absorption and approximately 756 nm after hydrogen absorption. To make the changes in the CDS spectral signal more intuitive, a peak signal appeared at the original CDS spectral zero point after signal conversion. Figure 4The results show that the simulated hydrogen sensor in this embodiment has good recognition ability for hydrogen. The conversion formula is: ,in, is the intensity of the converted signal, and ABS is the intensity of the original spectral signal.

[0059] Example 5: A hydrogen sensor was fabricated using a single planar chiral structure. The surface of a silicon wafer with an oxide layer thickness of 180 nm was cleaned with oxygen plasma at a power of 120 W for 5 min. Polymethyl methacrylate (PMMA) and a solvent were mixed at a volume ratio of 1:1. The mixture was then spin-coated onto the silicon wafer at a spin speed of 3000 rpm and an acceleration of 800 rpm / s for 30 s. The spin-coated silicon wafer was then baked at 160°C for 4 min on a hot plate. The baked silicon wafer surface was then etched using a scanning electron microscope electron beam etching system according to a preset pattern: a windmill pattern with a distance L of 640 nm between two diagonals and a distance W of 200 nm between two inner angles. The exposure dose was set to... After etching, the silicon wafer is first immersed in the developer for 15 seconds, then removed and immersed in the fixer for 30 seconds. After immersion, the silicon wafer is removed, rinsed with ultrapure water, and dried to obtain a silicon wafer with polymethyl methacrylate etched patterns on its surface.

[0060] Using a thermal evaporation coating machine Under vacuum, a Cr layer was first deposited on the surface of a silicon wafer with etched polymethyl methacrylate at a speed of 0.1 Å / s, followed by an Al layer at a speed of 1.5 Å / s. The silicon wafer with the Al layer was then immersed in acetone for 10 min and ultrasonically treated to remove the adhesive. The ultrasonically treated silicon wafer was then rinsed with ethanol and dried to obtain a sample with an Al layer.

[0061] Finally, a Pd layer was deposited on a silicon wafer with an Al layer at a rate of 0.2 Å / s to obtain the hydrogen sensor. The planar chiral structure of the hydrogen sensor has a diagonal distance L of 640 nm, a median distance W of 200 nm, a Cr layer thickness of 2 nm, an Al layer thickness of 25 nm, and a Pd layer thickness of 5 nm. SEM data of the fabricated hydrogen sensor are shown below. Figure 5 As shown.

[0062] The hydrogen sensor was placed under a dark-field scattering spectrometer with a 10× eyepiece and a 50× telephoto objective. A 5% VT hydrogen source outlet was positioned within 2 cm of the device surface. The hydrogen flow rate was controlled to approximately 80 mL / min using a gas flow meter. Right-hand circularly polarized scattering (RCP) and left-hand circularly polarized scattering (LCP) spectra were acquired at 0 min and 10 min. The CDS spectrum was obtained by subtracting the LCP spectrum from the RCP spectrum. The CDS spectrum was then denoised using the Savitzky-Golay algorithm with 400 sampling points and an order of 2. The denoised CDS spectrum was then converted using the same conversion formula as in Example 4.

[0063] refer to Figure 6 The experiment showed that the zero-point wavelength of the hydrogen sensor provided in this embodiment before hydrogen absorption was approximately 507 nm, and the zero-point wavelength after hydrogen absorption was approximately 537 nm. After signal conversion of the CDS spectra before and after hydrogen absorption, a spike signal appeared at the zero point of the original CDS spectrum. Figure 7 This indicates that it has a good ability to identify hydrogen.

[0064] like Figure 8 As shown, by adjusting the volume ratio of PdH in the Pd layer, the zero-point displacement response of the hydrogen sensor prepared in this embodiment to hydrogen detection under different hydrogen concentrations was simulated. The zero-point displacement response results corresponding to each PdH ratio were statistically analyzed, and the statistical results are shown in Table 1.

[0065] Table 1: Statistical Table of PdH Proportional Response to Zero-Point Displacement

[0066]

[0067] As can be seen from Table 1, the zero-point displacement increases with the increase of the proportion of PdH, indicating that the hydrogen sensor prepared in this embodiment has high sensitivity.

[0068] Examples 6-10: Five hydrogen sensors with Pd layer thicknesses of 1 nm, 3 nm, 5 nm, 7 nm, and 10 nm were simulated using the hydrogen sensor prepared in Example 5. The theoretical calculations yielded the hydrogen sensor responses to hydrogen at different Pd layer thicknesses, as shown in Table 2.

[0069] Table 2: Statistical Table of Pd Layer Thickness's Response to Zero-Point Displacement

[0070]

[0071] As shown in Table 2, hydrogen sensors with different Pd layer thicknesses all exhibit strong responsiveness to hydrogen and can detect the zero-point shift of the CDS spectrum before and after hydrogen absorption.

[0072] Examples 11-14: Referring to the hydrogen sensor prepared in Example 5, four hydrogen sensors were simulated. The ratio of the distance L between the two diagonals to the distance W between the two interior angles of the planar chiral structure was 16:5; the distances L between the two diagonals were 480 nm, 560 nm, 720 nm, and 800 nm, respectively. The theoretical calculations of the hydrogen sensor responses to hydrogen at different sizes are shown in Table 3.

[0073] Table 3: Statistical Table of Zero-Point Displacement Response Results by Distance L Between Two Diagonals

[0074]

[0075] As shown in Table 3, within the range of 480 nm to 800 nm between the two diagonals of the planar chiral structure, theoretical calculations show that hydrogen sensors of different sizes have strong responsiveness to hydrogen and can detect the zero-point shift change of the CDS spectrum before and after hydrogen absorption.

[0076] Example 15: A hydrogen sensor was simulated using a planar chiral structure array. This hydrogen sensor consisted of an array of four planar chiral structures A, B, C, and D. The Cr layer of each planar chiral structure was 2 nm thick, the Al layer was 25 nm thick, and the Pd layer was 5 nm thick. The ratio of L to W was 16:5. The distances L between the two diagonals of the four planar chiral structures were A: 480 nm, B: 560 nm, C: 640 nm, and D: 720 nm, respectively; adjacent planar chiral structures were spaced 5 μm apart. A hydrogen sensor was then simulated using only a single particle of the C planar chiral structure. Both sensors were subjected to CDS spectral simulation in the same hydrogen concentration simulation environment. The detection results of the two hydrogen sensors were compared. Figure 9 As shown. The results indicate that there is no significant difference between the detection results of the C-planar chiral structure in the hydrogen sensor based on the 5μm interval array structure and the detection results of the hydrogen sensor based on a single C-planar chiral structure. This suggests that under the 5μm interval distribution, the coupling resonance of the planar chiral structure in the array-based hydrogen sensor disappears, and its chiral optical response originates from the individual planar chiral structure itself.

[0077] Example 16: Referring to Example 15, a hydrogen sensor based on a planar chiral structure array is simulated. Six volume fractions of PdH are designed: 0%, 20%, 40%, 60%, 80%, and 100%. By simulating the formation of different proportions of PdH in the Pd layer, the zero-point displacement of the hydrogen sensor provided in this example for hydrogen detection under different hydrogen concentrations is simulated. The zero-point displacement of each planar chiral structure before and after hydrogen absorption under different PdH proportions is first obtained through theoretical calculations, referring to… Figure 10Then, all zero-point displacements are statistically analyzed to generate a color-coded thermal comparison chart, such as... Figure 11 As shown. In actual hydrogen concentration detection, the detected zero-point displacement is statistically analyzed to generate an actual thermogram. This thermogram is then compared with a thermometric reference image by color to determine the PdH ratio corresponding to the target, and thus the corresponding hydrogen concentration. The number of planar chiral structures in the array can be adjusted according to actual needs, and the size of each planar chiral structure is adjusted accordingly. Similarly, the hydrogen concentration gradient can be adjusted as needed, i.e., changing the PdH ratio gradient, and the number of thermograms in the thermometric reference image changes accordingly.

[0078] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A planar chiral structure, characterized in that, include: basal layer; The Cr layer is placed on the substrate layer; A surface plasmon material layer covers the Cr layer; A Pd layer is applied over a surface plasmon material layer. The planar chiral structure is a windmill shape composed of four identical right-angled triangles; The distance between the first vertices of two right triangles set opposite each other is called the distance between the two opposite angles L, and the distance between the second vertices of two right triangles set opposite each other is called the distance between the two interior angles W, and the ratio of L to W is (2~4):

1.

2. The planar chiral structure according to claim 1, characterized in that, The thickness of the Cr layer is 1~3nm; the thickness of the surface plasmon material layer is 23~27nm; and the thickness of the Pd layer is 1~10nm.

3. The planar chiral structure according to claim 1, characterized in that, The distance L between the two diagonals of the planar chiral structure is 480nm~800nm.

4. The planar chiral structure according to claim 1, characterized in that, The surface plasmon material is selected from at least one of Al or Au.

5. A method for preparing a planar chiral structure as described in any one of claims 1 to 4, characterized in that, include: S1. Spin-coat polymethyl methacrylate (PMMA) onto the substrate surface after oxygen plasma cleaning; bake the spin-coated PMMA substrate. S2. Etch the polymethyl methacrylate on the baked substrate surface according to the preset pattern; immerse the etched substrate in the developer first, and then in the fixer. After soaking, the substrate was removed, rinsed with ultrapure water, and dried to obtain a substrate with polymethyl methacrylate etched patterns on its surface. S3. First, deposit a Cr layer on the substrate layer with a polymethyl methacrylate etched pattern, then deposit a surface plasmon material layer; immerse the substrate layer after depositing the surface plasmon material layer in acetone and sonicate it. The ultrasonically treated substrate layer was rinsed with ethanol and dried to obtain a substrate layer with a surface plasmon material layer on the surface. S4. A Pd layer is deposited on a substrate layer with a surface plasmon material layer to obtain a planar chiral structure.

6. The method for preparing a planar chiral structure according to claim 5, characterized in that, The baking temperature described in S1 is 135℃~170℃, and the time is 3~5 minutes.

7. The method for preparing a planar chiral structure according to claim 5, characterized in that, The etching exposure dose set in S2 is 102.9~123.5 μC / cm. 2 .

8. The method for preparing a planar chiral structure according to claim 5, characterized in that, In S3, a Cr layer is deposited at a rate of 0.05 Å / s to 0.15 Å / s; a surface plasmon material layer is deposited at a rate of 1 Å / s to 2 Å / s. In S4, a Pd layer is deposited at a rate of 0.1 Å / s to 0.3 Å / s.

9. A hydrogen sensor, characterized in that, It includes at least one planar chiral structure as described in any one of claims 1 to 4.

10. The hydrogen sensor according to claim 9, characterized in that, When there are two or more planar chiral structures, the adjacent planar chiral structures are spaced at least 5 μm apart, and all planar chiral structures have different dimensions.

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