A high-sensitivity terahertz metasurface sensor and its preparation method

Abstract

The present invention provides a highly sensitive terahertz metasurface sensor, comprising: a substrate, a dielectric layer, a metal microstructure array, a super-lyophobic layer, and a lyophilic trap, wherein the dielectric layer is located on the substrate, a portion of the upper surface of the dielectric layer is covered by the metal microstructure array, and the remainder of the upper surface of the dielectric layer is covered by the super-lyophilic layer, the metal microstructure array includes a plurality of metal microstructure units, each of which is provided with a lyophilic trap at the point of maximum field strength, the lyophilic trap being disposed on the super-lyophilic layer and surrounded by the metal microstructure units. The terahertz metasurface sensor of the present invention introduces a super-lyophobic layer and a lyophilic trap array having lyophilic and lyophilic properties. Under the combined action of the super-lyophobic layer and the lyophilic trap array, liquid samples can autonomously gather at the point of maximum field strength of the metasurface sensor, thereby achieving ultrasensitive detection of trace liquid samples and making the detection more stable.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a high-sensitivity terahertz metasurface sensor and a preparation method thereof. Background Art

[0002] Terahertz waves refer to electromagnetic waves with wavelengths of 30-3000μm and frequencies between 0.1-10THz, lying between the infrared and microwave bands, and representing the transition zone from macroscopic electronics to microscopic optoelectronics. Due to their unique position in the electromagnetic spectrum, terahertz waves possess unique electromagnetic properties, including low photon energy, strong penetration, and distinct characteristic absorption peaks. The vibrational frequencies of many biological macromolecules fall within the terahertz band, exhibiting distinct characteristic absorption peaks. This allows sensors to detect trace amounts of substances with increased sensitivity. In recent years, due to the rapid development of micro- and nanofabrication technologies, terahertz metasurface sensors have been extensively researched in fields such as ecological and environmental monitoring, food and drug analysis, and chemical and biological product testing. They offer a highly sensitive detection method with simple pretreatment, non-destructive properties, and high sensitivity.

[0003] In current terahertz sensing research, most metasurface sensors are unable to achieve highly sensitive detection of certain ultra-low concentrations of analytes or trace substances, resulting in low reliability and limiting the development of terahertz sensing in many fields. Furthermore, the current method for fabricating terahertz metasurfaces is primarily traditional photolithography, which is complex, time-consuming, and expensive. Therefore, designing a metasurface sensor with higher sensitivity, improved sensing reliability, and more flexible fabrication methods in the terahertz band is a technical challenge that urgently needs to be addressed in the terahertz sensing field. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the present invention provides a high-sensitivity terahertz metasurface sensor to achieve high-sensitivity detection of trace liquid samples in the terahertz band.

[0005] The present invention achieves the above technical objectives through the following technical means.

[0006] A high-sensitivity terahertz metasurface sensor comprises: a substrate, a dielectric layer, a metal microstructure array, a super-lyophobic layer, and a lyophilic trap. The dielectric layer is located on the substrate, a portion of the upper surface of the dielectric layer is covered by the metal microstructure array, and the remaining portion of the upper surface of the dielectric layer is covered by the super-lyophobic layer. The metal microstructure array comprises a plurality of metal microstructure units, and a lyophilic trap is provided at the location with the maximum field intensity in each metal microstructure unit. The lyophilic trap is arranged on the super-lyophobic layer and surrounded by the metal microstructure units.

[0007] Furthermore, the metal microstructure unit is a U-shaped open ring structure.

[0008] Furthermore, the material of the metal microstructure unit includes gold, silver, and copper.

[0009] Furthermore, the thickness of the metal microstructure unit is 10-800 nm, and the characteristic size of the metal microstructure unit is in the μm-sub-mm order of magnitude.

[0010] Furthermore, the material of the dielectric layer is high-resistance silicon.

[0011] Furthermore, the thickness of the dielectric layer is 200 μm.

[0012] A method for preparing a high-sensitivity terahertz metasurface sensor, comprising:

[0013] A metal microstructure array is prepared on a metal-coated dielectric layer by laser etching and direct writing to form a terahertz metasurface.

[0014] The remaining surface of the dielectric layer except the metal microstructure array is removed, and a super-lyophobic layer is prepared by a laser surface treatment method;

[0015] The laser surface treatment method is used to process the liquid-affinity well at the location where the field intensity of the metal microstructure unit is the maximum.

[0016] Furthermore, the key parameters of laser direct writing are: wavelength 200-1700nm, pulse width 10fs-500ns, power 1-30w, scanning speed 10-1000mm / s, and number of scans 1-100 times.

[0017] Furthermore, the key parameters of laser direct writing are: wavelength 200-1700nm, pulse width 10fs-500ns, power 5-50w, scanning speed 10-2000mm / s, and number of scans 1-200 times.

[0018] Furthermore, the key parameters of laser direct writing are: wavelength 200-1700nm, pulse width 10fs-500ns, power 3-30w, scanning speed 10-1000mm / s, and number of scans 1-200 times.

[0019] Beneficial effects of the present invention:

[0020] The terahertz metasurface sensor described in the present invention introduces a super-lyophobic layer and a lyophilic well array with liquid-loving and liquid-repelling properties. Under the joint action of the super-lyophobic layer and the lyophilic well array, liquid samples can autonomously gather at the point where the field intensity of the metasurface sensor is maximum, thereby realizing ultra-sensitive detection of trace liquid samples and making the detection more stable.

[0021] The method for preparing the terahertz metasurface sensor described in the present invention greatly shortens the processing cycle by preparing the metasurface through a laser direct writing process, makes the processing process very flexible and designable, realizes efficient and high-quality metasurface precision processing, and has a wider range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the detection system of the terahertz metasurface sensor provided by the present invention;

[0023] Figure 2 A schematic diagram of the unit structure of a terahertz metasurface sensor provided in an embodiment of the present invention;

[0024] Figure 3 A flow chart of preparing a periodic structure, superphobic layer, and lyophilic trap for a terahertz metasurface sensor according to an embodiment of the present invention;

[0025] Figure 4 The electric field distribution diagram of the terahertz metasurface sensor at the resonance point provided by an embodiment of the present invention;

[0026] Figure 5 This is a frequency shift curve diagram after placing a trace amount of analyte on the unit structure provided by an embodiment of the present invention.

[0027] Reference numerals:

[0028] 1-Terahertz wave, 2-metal microstructure unit, 3-liquid analyte, 4-lyophilic trap, 5-superlyophobic layer, 6-substrate, 7-metal layer, 8-pulsed laser beam, 9-frequency shift curve without analyte, 10-frequency shift curve with full coverage of analyte, 11-frequency shift curve of analyte at the maximum field intensity. DETAILED DESCRIPTION

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more clearly understood, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways than those described herein, and those skilled in the art can make similar modifications without violating the scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0030] According to an embodiment of the present invention, a highly sensitive terahertz metasurface sensor comprises: a substrate 6, a dielectric layer, a metal microstructure array, a super-lyophobic layer 5, and a lyophilic trap 4. The dielectric layer is positioned on the substrate 6, a portion of the dielectric layer's upper surface is covered by the metal microstructure array, and the remainder of the dielectric layer's upper surface is covered by the super-lyophobic layer 5. The metal microstructure array comprises a plurality of metal microstructure units 2, each of which is provided with a lyophilic trap 4 at the point of maximum field intensity. The lyophilic trap 4 is disposed on the super-lyophobic layer 5 and surrounded by the metal microstructure units 2. The super-lyophobic layer 5 and the lyophilic trap 4 form a surface with differential surface wettability. When a liquid analyte is dripped onto the sensor surface, driven by the differential surface wettability, the liquid analyte autonomously aggregates in the lyophilic trap 4. The lyophilic trap 4 is positioned at the point of maximum field intensity in the metasurface sensor, promoting full interaction between the terahertz wave and the analyte, thereby enhancing the sensitivity of the terahertz metasurface sensor.

[0031] The metal microstructure array comprises a plurality of periodically arranged metal microstructure units 2. The metal microstructure array materials include, but are not limited to, gold, silver, copper, and the like. The metal microstructure units 2 have a thickness of 10-800 nm, with feature sizes ranging from μm to sub-mm. The dielectric layer is made of high-resistance silicon and has a thickness of 200 μm.

[0032] In this embodiment, the metal microstructure unit 2 is a U-shaped open ring made of silver with a thickness of 200 nm. The dielectric layer is made of high-resistance silicon with a thickness of 200 μm. The combined action of the super-lyophobic layer 5 and the lyophilic trap 4 allows the liquid phase analyte 3 to autonomously accumulate at the point of maximum field intensity on the metasurface. In the experiment, the terahertz wave 1 is incident perpendicularly on the sensor surface.

[0033] Figure 2 This is a schematic diagram of the unit structure of a terahertz sensor of the present invention. In order to determine the specific parameters of the structure, CST software was used for simulation calculation. Figure 1 and Figure 2 Electromagnetic simulations were performed using the designed structural and dimensional parameters, with the electromagnetic field propagating along the z-direction. Resonant units were periodically arranged along the x- and y-directions on the dielectric layer. The metal microstructure unit 2 had a period of 200 μm and a line width of 20 μm. The lyophilic well 4 within the open ring was 80 μm long and 100 μm wide.

[0034] according to Figure 3 The terahertz metasurface sensor is prepared by the following process. The specific processing steps are as follows:

[0035] 1) A silver film is grown on the surface of the silicon substrate 6 by a thermal evaporation coating process to form a metal layer 7. To increase the bonding strength between the silver film and the surface of the silicon substrate 6, a chromium film with a thickness of 10 nm and a silver film with a thickness of 200 nm are first evaporated on the surface of the silicon substrate 6 before the silver film is evaporated;

[0036] 2) Controlling an ultrafast laser scanning path to prepare an open ring array on the silver film, wherein the ultrafast laser has a wavelength of 355 nm, a pulse width of 15 ps, a power of 3-10 W, a scanning speed of 10-100 mm / s, and a scanning number of 5-40 times.

[0037] 3) Controlling laser parameters and processing environment to prepare a super-lyophobic layer 5 on the silicon substrate 6. The ultrafast laser has a wavelength of 355 nm, a pulse width of 15 ps, a power of 5-20 W, a scanning speed of 10-500 mm / s, a scanning pitch of 20 μm, and a scanning frequency of 1-100. Argon gas is continuously blown onto the sensor surface to reduce the heat-affected zone on the structure surface and improve the processing quality of the processing area.

[0038] 4) In the region of the metal microstructure unit 2 with the highest field intensity, the surface properties of the local region are irradiated with an ultrafast laser to control the formation of a lyophilic well 4. The ultrafast laser has a wavelength of 355 nm, a pulse width of 15 ps, a power of 5-20 W, a scanning speed of 10-1000 mm / s, a scanning pitch of 20 μm, and a scanning frequency of 1-200 times.

[0039] When the terahertz wave is incident on the sensor surface, the electric field intensity on the metal surface of the sensor will change. Figure 4 The electric field intensity at the resonant frequency of 0.44 THz is shown to be the maximum. Figure 5 The resonance peak shifts are shown when the analyte is spread over the entire sensor surface and when it is spatially concentrated at the point of maximum field intensity. When 10 μl of chlorothalonil solution is spread over the entire surface with a thickness of 1 μm, the resonance peak shifts by 8 GHz. When 10 μl of chlorothalonil solution is spatially concentrated at the point of maximum field intensity with a thickness of 3 μm, the resonance peak shifts by 14 GHz. This demonstrates that sensor sensitivity can be significantly improved by varying surface wettability.

[0040] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A high-sensitivity terahertz metasurface sensor, characterized in that: include: A substrate, a dielectric layer, a metal microstructure array, a super-lyophobic layer and a lyophilic trap, wherein the dielectric layer is located on the substrate, a portion of the upper surface of the dielectric layer is covered by the metal microstructure array, and the remaining portion of the upper surface of the dielectric layer is covered by the super-lyophobic layer. The metal microstructure array includes a plurality of metal microstructure units, and a lyophilic trap is provided at the point where the field intensity is maximum in each metal microstructure unit. The lyophilic trap is arranged on the super-lyophobic layer and surrounded by the metal microstructure units.

2. The high-sensitivity terahertz metasurface sensor according to claim 1, characterized in that: The metal microstructure unit is a U-shaped open ring structure.

3. The high-sensitivity terahertz metasurface sensor according to claim 1, characterized in that: The metal microstructure unit is made of gold, silver, and copper.

4. The high-sensitivity terahertz metasurface sensor according to claim 1, characterized in that: The thickness of the metal microstructure unit is 10-800 nm, and the characteristic size of the metal microstructure unit is in the order of µm to sub-mm.

5. The high-sensitivity terahertz metasurface sensor according to claim 1, characterized in that: The material of the dielectric layer is high-resistance silicon.

6. The high-sensitivity terahertz metasurface sensor according to claim 1, characterized in that: The thickness of the dielectric layer is 200 μm.

7. A method for preparing a high-sensitivity terahertz metasurface sensor according to claim 1, characterized in that: include: A metal microstructure array is prepared on a metal-coated dielectric layer by laser etching and direct writing to form a terahertz metasurface. The remaining surface of the dielectric layer except the metal microstructure array is removed, and a super-lyophobic layer is prepared by a laser surface treatment method; The laser surface treatment method is used to process the liquid-affinity well at the location where the field intensity of the metal microstructure unit is the maximum.

8. The preparation method according to claim 7, characterized in that Key parameters of laser direct writing: wavelength 200-1700nm, pulse width 10fs-500ns, power 1-30w, scanning speed 10-1000mm / s, number of scans 1-100 times.

9. The preparation method according to claim 7, characterized in that Key parameters of laser direct writing: wavelength 200-1700nm, pulse width 10fs-500ns, power 5-50w, scanning speed 10-2000mm / s, number of scans 1-200 times.

10. The preparation method according to claim 7, characterized in that Key parameters of laser direct writing: wavelength 200-1700nm, pulse width 10fs-500ns, power 3-30w, scanning speed 10-1000mm / s, number of scans 1-200 times.

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