Tunable graphene metamaterial sensor suitable for aerosol ink-jet printing

Abstract

The invention discloses a tunable graphene metamaterial sensor suitable for aerosol ink-jet printing, and belongs to the field of biomedical engineering. The tunable graphene metamaterial sensor is obtained by arranging a plurality of element atoms on a metal reflecting layer in an array; the element atom is composed of a structural layer, a substrate layer and a reflecting layer. Observed from the upper surface, element atoms of the metamaterial are composed of a circular ring structure; the circular ring structure is made of graphene; the substrate layer is a thick layer; the reflecting layer is a thin layer and is made of gold. And the meta-atoms are arranged in an array to obtain the metamaterial absorber. The interaction between the terahertz waves and the biomacromolecules is detected by matching the change of resonance frequency by utilizing the resonance absorption characteristics of the terahertz waves and the biomacromolecules, so that the detection sensitivity of the biomacromolecules is improved. By measuring the absorption characteristics of the terahertz metamaterial sensor under different biological analyte refractive indexes, enhanced detection of biological sensing is realized, and the interaction effect of terahertz waves and biological macromolecules can be detected.

Description

Technical Field

[0001] The present invention relates to a tunable graphene metamaterial sensor applicable to aerosol inkjet printing, belonging to the field of biomedical engineering. Background Art

[0002] The exploration of human beings themselves is one of the most complex disciplinary researches. The life information shown from DNA to the complete individual is the research focus of modern life sciences. The biological information of the overall disease symptoms shown by an individual has been proven by medical practice to be an effective measure of the degree of human diseases and health status. The carriers of these detectable disease information are called biomarkers in pathology. Biosafety and human health are the key concerns in today's society. The rapid and accurate detection of biomarkers is a necessary means for biosafety prevention and human health monitoring. Currently, the in vitro analysis methods applied to biomarkers mainly include mass spectrometry, quantitative polymerase chain reaction, enzyme-linked immunosorbent assay, electrochemistry technology of bio-modified electrodes, and surface plasmon resonance, etc.

[0003] However, there are still technical limitations or deficiencies in the popularization and application of existing detection methods. For example, ordinary mass spectrometry cannot quickly and accurately judge diseases, and complex screening and enrichment of samples are required; the bioenzymes in ELISA are relatively fragile and costly, and their biological activities are greatly affected by environmental factors, making them inapplicable to long-term storage and repeated detection; electrochemical detection methods do not have specific detection capabilities by themselves, so they highly rely on surface nano-modifiers and are prone to signal overlap and interference among multiple substances; the detection methods based on SPR have poor selectivity, rely on the modification of bioenzymes on the metal surface, are easily interfered by the external detection environment, and have low sensitivity.

[0004] Terahertz radiation wave refers to the electromagnetic wave with a frequency range of 0.1 THz to 10 THz, and the wavelength is approximately between 0.03 mm and 3 mm. This waveband is exactly located at the junction of microwaves and infrared rays. The terahertz bio-spectral analysis technology based on terahertz waves is a new bio-sensing technology, with characteristics such as transience, non-contact, non-destructiveness, and specificity. However, the terahertz radiation has a long wavelength and poor focusing effect, resulting in a weak interaction between free-space terahertz waves and biological substances, and the generated terahertz absorption spectra and photoacoustic spectra signals are weak. Therefore, conventional terahertz bio-detection technologies have disadvantages such as low sensitivity, large sample consumption, and being unfavorable for low-concentration detection, and cannot fully meet the requirements of high-sensitivity bio-detection.

[0005] In summary, aiming at the defects of the above methods, a terahertz bio-sensing enhancement method based on graphene metasurface is proposed, which can effectively improve the detection sensitivity of the detected biomolecules. Summary of the Invention

[0006] The first object of the present invention is to provide a tunable graphene metamaterial sensor applicable to aerosol inkjet printing, which realizes tunable absorption of electromagnetic waves in the terahertz band based on the artificial periodic structure of the graphene metasurface and has the advantage of high wave absorption efficiency. The present invention can utilize the resonance absorption characteristics of terahertz waves and biological macromolecules, and detect the interaction between terahertz waves and biological macromolecules by matching the change of resonance frequency, thereby improving the detection sensitivity of the biological macromolecules.

[0007] Based on a tunable graphene metamaterial sensor applicable to aerosol inkjet printing disclosed in the present invention, the second object of the present invention is to realize enhanced detection of biosensing by measuring the absorption characteristics of the terahertz metamaterial at different refractive indices of biological analytes, and to be able to detect the interaction effect between terahertz waves and biological macromolecules.

[0008] The object of the present invention is achieved by the following technical solutions.

[0009] A tunable graphene metamaterial sensor applicable to aerosol inkjet printing disclosed in the present invention is obtained by arranging meta-atoms in an array on a metal reflective layer; the meta-atom is composed of a structural layer, a base layer and a reflective layer.

[0010] For the structural configuration of the sensor, when observed from the upper surface, the meta-atom of the metamaterial is composed of a circular ring structure; the material of the circular ring structure is graphene; the base layer is a thick layer, and the material used is polyimide; the reflective layer is a thin layer, and the material used is gold. The meta-atom array is arranged to obtain the metamaterial, that is, the sensor.

[0011] The thickness of the circular ring structure is 10 μm.

[0012] The thickness of the base layer of nitrosamide is 75 μm.

[0013] The metal reflective layer is located below the polyimide, and its thickness needs to be greater than its skin depth.

[0014] The metal reflective layer is usually a metal, and its thickness needs to be greater than its skin depth. As a further preference, the thickness of the selected metal is 0.05 μm.

[0015] The tunable graphene metamaterial sensor with an artificial periodic structure utilizes the resonance absorption characteristics of terahertz waves and biological macromolecules, detects the interaction between terahertz waves and biological macromolecules by matching the change of resonance frequency, enhances the interaction between terahertz waves and biological macromolecules, realizes a strong coincidence enhancement between the terahertz resonance peak and the intrinsic terahertz "fingerprint spectrum" of the biomarker, thereby improving the detection sensitivity of biological macromolecules.

[0016] By measuring the absorption characteristics of a terahertz metamaterial sensor at different refractive indices of bioanalytes, the interaction effect between terahertz waves and biological macromolecules is detected. When the refractive index of the analyte to be measured changes, the resonant frequency of the terahertz metamaterial sensor will undergo a red shift or a blue shift. By changing the frequency change and the change in the radius parameter of the metasurface graphene ring, the detection accuracy for biomarkers is adjusted. At the same time, by adjusting the chemical potential of graphene, the resonance peak of the sensor can be finely tuned to achieve precise detection of biological macromolecules.

[0017] By adding an external material with a controllable refractive index on the structural layer and controlling its refractive index to range from n = 1 to n = 1.5, the tunable graphene metamaterial sensor can be used to achieve 99.9% electromagnetic wave absorption tunable in the range of 500 GHz - 673 GHz.

[0018] By adjusting the radius of the graphene ring from r = 35 to r = 55, the tunable graphene metamaterial sensor is used to achieve 70.7% electromagnetic wave absorption (-3dB absorption) tunable in the range of 540 GHz - 690 GHz, where 99.9% absorption is achieved at 558 GHz and 670 GHz.

[0019] By adjusting the chemical potential of graphene from 0.2 eV to 1 eV, the tunable graphene metamaterial sensor is used to achieve 70.7% to 99.9% electromagnetic wave absorption adjustable in a small range. The tuning characteristics of the sensor are reflected by adjusting the absorption range and the optimal frequency absorption point by changing the chemical potential.

[0020] A tunable graphene metamaterial sensor suitable for aerosol inkjet printing disclosed by the present invention uses an aerosol inkjet printing process to process a terahertz band sensor based on graphene, which is used to manufacture various micro-nano structures, has high precision, can manufacture fine structures, and has a relatively low cost.

[0021] A manufacturing method of a tunable graphene metamaterial sensor suitable for aerosol inkjet printing disclosed by the present invention includes the following preparation steps:

[0022] Step 1: Ultrasonically clean a flexible PI substrate with dimensions of 200 μm × 200 μm in acetone and isopropyl alcohol for 10 to 12 minutes respectively, and then dry it with a nitrogen gun.

[0023] Step 2: Use a plasma sputtering instrument to sputter a 0.04 μm - 0.06 μm thick gold layer on the surface of the PI substrate.

[0024] Step 3: Convert the graphene dispersion into aerosol droplets of 1 μm - 10 μm through an ultrasonic atomizer.

[0025] Step 4: Clean the print head and substrate of the aerosol inkjet printer, adjust the printing parameters, control the aerosol flow rate and printing accuracy, and use aerodynamic focusing technology to eject aerosol droplets onto the target substrate to form a graphene pattern.

[0026] Step 5: Place the printed graphene pattern in an oven for heat treatment, control the temperature between 200°C and 400°C, remove the solvent by annealing, improve the structural stability and electrical conductivity of graphene, and thus obtain a tunable graphene metamaterial sensor.

[0027] Preferably, in Step 1, the flexible PI substrate with a size of 200μm×200μm is ultrasonically cleaned with acetone and isopropyl alcohol for 10 minutes respectively, and then dried with a nitrogen gun.

[0028] Preferably, in Step 2, a 0.05μm thick gold layer is sputtered on the surface of the PI substrate using a plasma sputtering instrument.

[0029] Beneficial effects:

[0030] 1. A tunable graphene metamaterial sensor suitable for aerosol inkjet printing disclosed by the present invention is obtained by arranging a plurality of meta-atoms in an array on a metal reflection layer; the meta-atom is composed of a structural layer, a base layer and a reflection layer. For the structural configuration of the sensor, the meta-atom of the metamaterial is composed of a circular ring structure; the material of the circular ring structure is graphene; the base layer is a thick layer, and the material used is polyimide; the reflection layer is a thin layer, and the material used is gold. The meta-atom array is arranged to obtain a metamaterial sensor, and different layers in the three-layer structure of the sensor can interact with each other to enhance the electromagnetic resonance effect, thereby improving the absorption or reflection efficiency of electromagnetic waves with specific frequencies.

[0031] 2. A tunable graphene metamaterial sensor suitable for aerosol inkjet printing disclosed by the present invention, terahertz waves are very sensitive to the weak interactions between biomolecules, can capture changes in molecular structure, conformation and the microenvironment around the molecule, and improve the detection sensitivity of biological macromolecules. By detecting the concentration change of biomolecules, it is of great significance for early disease diagnosis and the like.

[0032] 3. A tunable graphene metamaterial sensor suitable for aerosol inkjet printing disclosed by the present invention has fingerprint recognition characteristics. The terahertz frequency band contains a large amount of spectral information related to the vibration and rotation of biomolecules, and different biomolecules have unique spectral "fingerprints" in the terahertz band. By analyzing the fingerprint characteristics, specific recognition of biomolecules can be achieved, avoiding cross-reactions and misjudgments that may occur in traditional methods, and at the same time, the detection process of biological macromolecules can be simplified and the cost can be reduced.

[0033] 4. A tunable graphene metamaterial sensor applicable to aerosol inkjet printing also has significant advantages in terms of safety. The terahertz photon energy is very low, which will not cause ionization radiation to biological samples, will not damage biomolecules and cells, and will not pose a hazard to the health of operators. This is a significant advantage compared with ionization radiation detection methods such as X-rays and gamma rays.

[0034] 5. A tunable graphene metamaterial sensor applicable to aerosol inkjet printing uses an aerosol inkjet printer to process the tunable graphene metamaterial sensor and, in conjunction with the detection of biological macromolecules based on terahertz spectrum analysis, can achieve enhanced detection of biosensing.

[0035] 6. A tunable graphene metamaterial sensor applicable to aerosol inkjet printing uses an aerosol inkjet printing process to fabricate a terahertz band sensor based on graphene. The aerosol inkjet printing technology can fabricate micro-nano optical structures such as optical waveguides and optical sensors, and has high precision and high resolution. The optical material ink is ejected onto the substrate through an aerosol inkjet printing device to form the required optical structure. By optimizing the printing parameters, micron-scale or even nano-scale feature sizes can be achieved. It can achieve the single-molecule detection sensitivity applicable to biosensing and chemical substance detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the sensor unit, where Figure 1 (a) is the top view, Figure 1 (b) is the side view;

[0037] Figure 2 It is the sensing characteristic diagram of the sensor;

[0038] Figure 3 It is the change of the absorption rate spectrum line of the sensor at a ring radius of 35–55 nm;

[0039] Figure 4 It is the change of the absorption rate spectrum line of the sensor at a chemical potential of 0.2–1 eV;

[0040] Figure 5 It is the process schematic diagram of the aerosol inkjet printer;

[0041] Figure 6 It is the flow chart of biomarker detection. DETAILED DESCRIPTION OF THE INVENTION

[0042] .To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] As Figure 1 shown, a tunable graphene metamaterial sensor applicable to aerosol inkjet printing disclosed in this embodiment is obtained by arranging meta-atoms in an array on a metal reflection layer; the meta-atom is composed of a structural layer, a base layer and a reflection layer.

[0044] S1: Observed from the cross-section, the meta-atom of the metamaterial is composed of a structural layer, a base layer and a reflection layer (from top to bottom).

[0045] S2: Observed from the upper surface, the meta-atom of the metamaterial is composed of a rectangle and a ring.

[0046] The structural layer in the feature S1 is usually a thin layer, which can be 50 nm to 500 nm; the structural layer adopts an annular structure, and the material used is graphene.

[0047] The thickness of the annular structure is 10 μm.

[0048] The base layer in the feature S1 is usually a thick layer, and the material used is polyimide.

[0049] The thickness of the base layer of nitrosamide is 75 μm.

[0050] The reflection layer in the feature S1 is a thin layer, and the material used is gold. The metal reflection layer usually requires the metal thickness to be greater than its skin depth. As a further preference, the thickness of the selected metal is 0.05 μm.

[0051] The material used for the ring structure in the feature S2 is graphene. By changing the size of this material, the resonance peak of the metamaterial is changed. Through testing and fitting, tuning curves as Figure 2 , Figure 3 and Figure 4 shown can be obtained.

[0052] The tunable graphene metamaterial sensor with an artificial periodic structure utilizes the resonance absorption characteristics of terahertz waves and biological macromolecules, detects the interaction between terahertz waves and biological macromolecules by matching the change of the resonance frequency, enhances the interaction between terahertz waves and biological macromolecules, realizes a strong coincidence enhancement between the terahertz resonance peak and the intrinsic terahertz "fingerprint" of the biomarker, thereby improving the detection sensitivity of biological macromolecules.

[0053] As Figure 2As shown, by adding an external material with a controllable refractive index on the structural layer, controlling the refractive index from n = 1 to n = 1.5, this graphene-based metamaterial sensor for the terahertz band can achieve 99.9% electromagnetic wave absorption adjustable in the range of 500 GHz - 673 GHz.

[0054] By measuring the absorption characteristics of the terahertz metamaterial sensor at different refractive indices of bioanalytes, the interaction effect between terahertz waves and biological macromolecules is detected. When the refractive index of the analyte to be measured changes, the resonant frequency of the terahertz metamaterial sensor will undergo a red shift or a blue shift. By changing the frequency change and the change in the radius parameter of the metasurface graphene ring, the detection accuracy for biomarkers is adjusted.

[0055] As Figure 3 shown, by adjusting the radius of the graphene ring (from r = 35 to r = 55), this graphene-based tunable sensor for the terahertz band can achieve 70.7% electromagnetic wave absorption (-3 dB absorption) adjustable in the range of 540 GHz - 690 GHz. Among them, 99.9% absorption is achieved at 558 GHz and 670 GHz.

[0056] At the same time, by adjusting the chemical potential of graphene, the resonance peak of the sensor can be finely tuned to achieve precise detection of biological macromolecules.

[0057] As Figure 4 shown, by adjusting the chemical potential of graphene (from 0.2 eV to 1 eV), this graphene-based tunable sensor for the terahertz band can achieve a small range of adjustable 70.7% (-3 dB absorption to 99.9% electromagnetic wave absorption). The tuning characteristics of the sensor are reflected by adjusting the absorption range and the optimal frequency absorption point by changing the chemical potential.

[0058] As Figure 5 shown, a method for fabricating a tunable graphene metamaterial sensor applicable to aerosol inkjet printing disclosed in this embodiment is as follows:

[0059] S1. Ultrasonically clean the flexible PI substrate with acetone and isopropanol for 10 min respectively, and dry it with a nitrogen gun. The size of the PI substrate is 200 μm × 200 μm.

[0060] S2. Sputter a 0.05-μm gold layer on the surface of the PI substrate using a plasma sputtering instrument.

[0061] S3. Generate an aerosol (usually particles of 1 - 10 microns) from the graphene dispersion liquid through an atomization device. The aerosol is composed of tiny liquid droplets generated from a liquid substance through an atomizer and enters the air stream to form an aerosol mist.

[0062] S4. Clean the print head and substrate of the aerosol inkjet printer to ensure dust-free and pollution-free. Feed the aerosol into the print head through a pipeline to ensure the uniformity and stability of the ink droplets.

[0063] S5. Adjust the printing parameters, control the aerosol flow rate and the accuracy of inkjet printing, eject the aerosol from the print head onto the target substrate, and use aerodynamic focusing technology to collimate the dense aerosol mist droplets filled with materials into a tightly controlled beam of materials.

[0064] S6. The aerosol is ejected from the print head onto the substrate surface and printed along a predetermined path. This process is precisely controlled by an electric control system to achieve high-precision inkjet.

[0065] S7. Cure or heat-treat the printed graphene pattern to improve its structural stability and electrical conductivity. Use an oven to heat-treat the printed graphene pattern, controlling the temperature between 200°C and 400°C. Annealing can remove the solvent and improve the electrical conductivity of graphene.

[0066] S8. After the printing process is completed, perform quality inspection on the printed graphene pattern to ensure its complete structure and good electrical conductivity.

[0067] Figure 6 For the flowchart of biomarker detection, as Figure 6 shown, a tunable graphene metamaterial sensor applicable to aerosol inkjet printing disclosed in this embodiment is used to detect biomarkers, and the specific implementation steps are as follows:

[0068] S1. Transmitter: Used to emit the optical signal required for detection.

[0069] S2. Collimator 1: Used to collimate the optical signal emitted by the transmitter to form a parallel light beam.

[0070] S3. Collimator 2: Used to receive and collimate the optical signal reflected or transmitted from the sample.

[0071] S4. Collimator 3 and Collimator 4: Used to adjust the optical path to ensure that the optical signal irradiates the sample correctly and receives the optical signal reflected or transmitted from the sample.

[0072] S5. Sample: The sample where the biomarker to be detected is located.

[0073] S6. Receiver: Used to receive the optical signal processed by the sample and convert it into an electrical signal for further analysis.

[0074] In implementation, the transmitter emits an optical signal of a specific wavelength, which forms a parallel light beam through the collimator 1 and is precisely irradiated onto the sample after being adjusted by the collimators 3 and 4. The biomarker in the sample absorbs, scatters, or fluoresces the optical signal, and the generated signal is collimated by the collimator 2 and then transmitted to the receiver. The receiver converts the optical signal into an electrical signal, and through subsequent signal processing and analysis, the presence and concentration of the biomarker are determined.

[0075] The above specific description further elaborates on the purpose, technical solution, and beneficial effects of the invention. It should be understood that the above is only a specific embodiment of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An adjustable graphene metamaterial sensor applicable to aerosol inkjet printing, characterized in that: It is obtained by arranging a number of meta - atoms in an array on a metal reflection layer; the meta - atom is composed of a structural layer, a base layer, and a reflection layer; For the structural configuration of the sensor, when observed from the upper surface, the meta - atoms of the metamaterial consist of a circular ring structure; the material of the circular ring structure is graphene; The base layer is a thick layer, and the material used is polyimide; the reflection layer is a thin layer, and the material used is gold; the meta - atom array is arranged to obtain the metamaterial, that is, the sensor.

2. The tunable graphene metamaterial sensor applicable to aerosol inkjet printing according to claim 1, wherein: The thickness of the circular ring structure is 10 μm; The thickness of the base layer of nitrosoamide is 75 μm; The metal reflection layer is located below the polyimide, and its thickness is greater than its skin depth.

3. The tunable graphene metamaterial sensor applicable to aerosol inkjet printing according to claim 2, wherein: The thickness of the selected metal is 0.05 μm.

4. An adjustable graphene metamaterial sensor applicable to aerosol inkjet printing according to claim 1, 2 or 3, characterized in that: The tunable graphene - based metamaterial sensor with an artificial periodic structure utilizes the resonant absorption characteristics of terahertz waves and biological macromolecules, detects the interaction between terahertz waves and biological macromolecules by matching the change in the resonant frequency, enhances the interaction between terahertz waves and biological macromolecules, realizes a strong coincidence enhancement between the terahertz resonance peak and the intrinsic terahertz "fingerprint" of the biomarker, thereby improving the detection sensitivity of biological macromolecules.

5. An adjustable graphene metamaterial sensor applicable to aerosol inkjet printing according to claim 1, 2 or 3, characterized in that: By measuring the absorption characteristics of the terahertz metamaterial sensor at different refractive indices of biological analytes, the interaction effect between terahertz waves and biological macromolecules is detected; when the refractive index of the analyte to be measured changes, the resonant frequency of the terahertz metamaterial sensor will undergo a red - shift or a blue - shift. By changing the frequency change and the change in the radius parameter of the graphene ring on the metasurface, the detection accuracy for biomarkers is adjusted; at the same time, by adjusting the chemical potential of graphene, the resonant peak of the absorber can be finely tuned to achieve precise detection of biological macromolecules.

6. The tunable graphene metamaterial sensor applicable to aerosol inkjet printing according to claim 5, characterized in that: By adding an external material with a tunable refractive index on the structural layer, controlling the refractive index from n = 1 to n = 1.5, the tunable graphene - based metamaterial sensor is used to achieve 99.9% electromagnetic wave absorption adjustable in the range of 500 GHz - 673 GHz.

7. The tunable graphene metamaterial sensor applicable to aerosol inkjet printing according to claim 5, wherein: By adjusting the radius of the graphene ring from r = 35 to r = 55, the tunable graphene - based metamaterial sensor is used to achieve 70.7% electromagnetic wave absorption adjustable in the range of 540 GHz - 690 GHz, where 99.9% absorption is achieved at 558 GHz and 670 GHz.

8. The tunable graphene metamaterial sensor applicable to aerosol inkjet printing according to claim 5, wherein: By adjusting the chemical potential of graphene from 0.2 eV to 1 eV, the tunable graphene - based metamaterial sensor is used to achieve a small - range adjustable 70.7% - 99.9% electromagnetic wave absorption; the tuning characteristics of the absorber are reflected by adjusting the change in the chemical potential to adjust the absorption range and the optimal frequency absorption point.

9. The tunable graphene metamaterial sensor applicable to aerosol inkjet printing according to claim 1, 2 or 3, characterized in that: The manufacturing method includes the following preparation steps: Step 1: Ultrasonically clean the flexible PI substrate with dimensions of 200 μm×200 μm in acetone and isopropanol for 10 minutes to 12 minutes respectively, and then dry it with a nitrogen gun; Step 2: Use a plasma sputtering instrument to sputter a gold layer with a thickness of 0.04 μm to 0.06 μm on the surface of the PI substrate; Step 3: Convert the graphene dispersion liquid into aerosol droplets with a size of 1 μm to 10 μm through an ultrasonic atomizer; Step 4: Clean the print head and substrate of the aerosol inkjet printer, adjust the printing parameters, control the aerosol flow rate and printing accuracy, and use the aerodynamic focusing technology to eject the aerosol droplets onto the target substrate to form a graphene pattern; Step 5: Put the printed graphene pattern into an oven for heat treatment, control the temperature between 200°C and 400°C, remove the solvent by annealing, improve the structural stability and electrical conductivity of the graphene, and then obtain a tunable graphene metamaterial sensor.

10. A tunable graphene metamaterial sensor applicable to aerosol inkjet printing according to claim 9, wherein: In Step 1, the flexible PI substrate with a size of 200μm×200μm is ultrasonically cleaned with acetone and isopropyl alcohol for about 10 minutes respectively, and then dried with a nitrogen gun; In Step 2, a 0.05μm thick gold layer is sputtered on the surface of the PI substrate using a plasma sputtering instrument.

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