Terahertz metasurface biosensor with double-sided independent sensing function

Abstract

The invention provides a terahertz metasurface biosensor with a double-sided independent sensing function, and relates to the technical field of biomedical detection and advanced materials, and the terahertz metasurface biosensor comprises: a substrate which is made of a material with high permeability to terahertz waves and has a thickness of 100 m; the first resonator array is integrated on the front surface of the substrate and comprises a plurality of first resonators which are periodically arranged along the X axis and the Y axis of the substrate; the first resonator is an asymmetric split ring resonator, the radius of a circular ring-shaped main body is 30 m, the annular width is 5 m, and the opening width is 5 m; and the second resonator array is integrated on the back surface of the substrate and comprises a plurality of second resonators which are periodically arranged along the X axis and the Y axis of the substrate, the second resonators are asymmetric split ring resonators, the radius of an annular main body is 17.5 m, the annular width is 3 m, and the opening width is 3 m. The biosensor provided by the invention realizes a double-sided sensing function, and double-sided sensing is mutually independent and does not influence each other, so that the sensing accuracy and efficiency are greatly improved.

Description

Technical Field

[0001] The present invention relates to the fields of biomedical detection technology and advanced materials, and in particular to a terahertz supersurface biosensor with double-sided independent sensing functions. Background Art

[0002] Terahertz (THz) waves, electromagnetic waves located between the infrared and microwave frequency bands, show great potential for application in the biomedical field due to their low photon energy, strong penetration ability, and fingerprint spectral response to various materials. However, the sensitivity of THz biosensing technology is limited due to insufficient THz radiation power and the relative mismatch between the material to be detected and the THz wavelength. These challenges can be overcome by combining THz technology with metasurface technology. As an artificial structure composed of a periodic arrangement of subwavelength unit cells, metasurfaces show excellent performance in manipulating the phase, amplitude, and polarization of electromagnetic waves. The diverse resonance modes of metasurfaces, such as dipoles, Fano resonances, and electromagnetically induced transparency (EIT), can generate highly localized strong electric fields to enhance the interaction between light and matter. Among them, continuum bound states (BICs) have attracted widespread attention because they can produce resonances with infinite quality (Q) factors. In theory, BICs, as stable intrinsic wave states, can trap light for an infinite time, but their non-radiative properties, namely the vanishing spectral linewidth, limit their practical applications. Through clever symmetry breaking, BICs can be transformed into quasi-bound states (QBICs) with limited radiation leakage, providing an important method for the innovative design of high Q-factor optical devices. In the process of realizing the present invention, the applicant found that the current research on the realization of QBICs mainly focuses on the single-sided etching microstructure of the metasurface to create enhanced local field confinement. This method only utilizes one side of the metasurface, resulting in insufficient detection efficiency and a single sensing result, limiting its potential for wider application in biosensing. The contradiction between the complex structure and high heterogeneity of biomacromolecules, the limited sensing efficiency and the need to characterize complex sensing signals is becoming increasingly prominent, which brings great technical difficulties to the widespread application of terahertz metasurface biosensing. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art or related technology, and provides a terahertz metasurface biosensor with double-sided independent sensing function, thereby realizing a terahertz metasurface biosensor device with double-sided sensing function, and the double-sided sensing is independent of each other and does not affect each other, so that the accuracy and efficiency of sensing are greatly improved.

[0004] The present invention is realized through the following technical scheme: a terahertz metasurface biosensor with double-sided independent sensing function, comprising: a substrate, made of a material with high terahertz wave permeability, with a thickness of 100µm; a first resonator array, integrated on the front side of the substrate, comprising a plurality of first resonators periodically arranged along the X-axis and the Y-axis of the substrate; the first resonator is an asymmetric open ring resonator, the annular body radius of the first resonator is 30µm, the annular width is 5µm, and the opening width is 5µm; a second resonator array, integrated on the back side of the substrate, comprising a plurality of second resonators periodically arranged along the X-axis and the Y-axis of the substrate, the second resonator is an asymmetric open ring resonator, the annular body radius of the second resonator is 17.5µm, the annular width is 3µm, and the opening width is 3µm.

[0005] In this technical solution, a double-sided metasurface is realized (the first resonator array is located on the front side of the substrate, and the second resonator array is located on the back side of the substrate. The double-sided metasurface is constructed by two layers of different asymmetric split ring resonators (ASRs). Based on the principle of quasi-continuum bound state (QBIC), under the irradiation of THz waves, the resonant structure on both sides of the metal surface exhibits two independent QBICs with high sensitivity (169 and 325 GHz / RIU, respectively). The thickness of the substrate can not only avoid mutual coupling and interference of the double-sided structure and realize independent sensing function, but also minimize the loss of terahertz energy and increase the sensitivity of sensing.

[0006] According to the terahertz metasurface biosensor with double-sided independent sensing function provided by the present invention, preferably, in the first resonator array, the distance between the resonators is 20µm; in the second resonator array, the distance between the resonators is 5µm.

[0007] According to the terahertz metasurface biosensor with double-sided independent sensing function provided by the present invention, preferably, the resonance frequency of the first resonator array is 0.726 THz; the resonance frequency of the second resonator array is 1.961 THz.

[0008] According to the terahertz metasurface biosensor with double-sided independent sensing function provided by the present invention, preferably, the substrate is made of quartz with a thickness of 100 µm.

[0009] According to the terahertz metasurface biosensor with double-sided independent sensing function provided by the present invention, preferably, the material of the first resonator and the second resonator is gold with a thickness of 100 nanometers. According to the terahertz metasurface biosensor with double-sided independent sensing function provided by the present invention, preferably, a titanium layer is provided between the resonator and the substrate, and the thickness of the titanium layer is 10 nanometers.

[0010] According to the terahertz metasurface biosensor with double-sided independent sensing function provided by the present invention, preferably, the asymmetric open ring resonator has two openings, and the openings divide the circular ring body of the resonator into a semicircle and a circular arc to form an asymmetric structure.

[0011] According to the terahertz metasurface biosensor with double-sided independent sensing function provided by the present invention, preferably, the integration method of the first resonator and the second resonator includes: treating the substrate with an acetone solution and ultrasonically cleaning it, rinsing it with deionized water, and blowing it dry with nitrogen; patterning the surface of the substrate using photolithography technology to form corresponding patterns of the first resonator array and the second resonator array; depositing a 10-nanometer-thick titanium layer and a 100-nanometer-thick gold film on the substrate by magnetron sputtering, the titanium layer being located between the gold film and the substrate; and removing excess material using deep silicon etching technology to leave the first resonator array and the second resonator array.

[0012] The beneficial effects achieved by the present invention include at least: selecting 100um thick quartz as the substrate of the metasurface, which can not only make the resonance of the double-sided metal structure uncoupled from each other to achieve the function of double-sided independent sensing, but also minimize the loss of terahertz energy and achieve a higher sensing intensity. Double QBIC peaks are achieved, and the double BICs are independent of each other, both of which can provide higher sensing performance. The sensing performance of the double-sided metasurface is comparable to that of the previously reported single-sided QBIC metasurface sensor, but it has double-sided sensing capabilities, which increases the efficiency of sensing, can simultaneously characterize the changes of two substances, and the double-sided sensing is independent of each other, and mutually verified during detection, which increases the accuracy and stability of ultra-sensitive sensing, showing broad application prospects in the field of biological detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 A front structural schematic diagram of a terahertz metasurface biosensor with double-sided independent sensing functions according to an embodiment of the present invention is shown.

[0014] Figure 2 A schematic diagram of the structure of an asymmetric split ring resonator monomer according to an embodiment of the present invention is shown.

[0015] Figure 3 A schematic diagram of the back structure of a terahertz metasurface biosensor with double-sided independent sensing functions according to an embodiment of the present invention is shown.

[0016] Figure 4 A perspective structural schematic diagram of a terahertz metasurface biosensor with double-sided independent sensing functions according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0017] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] like Figure 1 , Figure 2 and Figure 3 As shown, an embodiment of the present invention discloses a terahertz metasurface biosensor with double-sided independent sensing function, comprising: a substrate 1, made of a material with high terahertz wave permeability, with a thickness of 100µm; a first resonator array, integrated on the front side (top side) of the substrate, comprising a plurality of first resonators 2 periodically arranged along the X-axis and the Y-axis of the substrate, with an arrangement period of P 1 =80µm; the first resonator is an asymmetric split ring resonator, and the radius of the annular body of the first resonator is r 1 =30µm, the ring width is w 1 =5µm, opening width d 1 =5µm; the second resonator array, integrated on the back side of the substrate (back side), includes a plurality of second resonators 3 periodically arranged along the X-axis and Y-axis of the substrate, with an arrangement period of P 2 =40µm; the second resonator is an asymmetric split ring resonator, and the radius of the annular body of the second resonator is r 2 =17.5µm, the ring width is w 2 =3µm, opening width d 2 =3µm.

[0019] like Figure 4 As shown, in this embodiment, the metasurface is carefully constructed by two layers of different asymmetric split ring resonators (ASRs). The unit cell on the top side includes a 1 =30µm, width w 1 =5µm semicircle and arc, the gap distance d between the semicircle structure and the arc structure 1 =5µm. Each unit cell is a square periodically arranged along the X-axis and Y-axis, with a period of P 1 = 80 µm. The unit cell on the back side is proportionally reduced to nearly half the size of the top side, and the corresponding parameters are marked as r 2 =17.5µm, w 2 =3µm, d 2 =3µm and p 2 =40µm.

[0020] According to another embodiment of the present invention, a method for preparing a terahertz metasurface biosensor with double-sided independent sensing function is also disclosed: the metasurface is manufactured by standard micro / nano processing technology. First, a 100µm thick quartz substrate is treated with an acetone solution, ultrasonically cleaned, rinsed with deionized water, and blown dry with nitrogen. Then, the top surface of the substrate is patterned using photolithography, and then a 100-nanometer-thick gold (Au) film and a 10-nanometer-thick titanium (Ti) adhesion layer are deposited on the substrate by magnetron sputtering. The titanium layer acts as an intermediary to improve the interface between the gold film and the substrate, thereby ensuring a more secure and durable attachment. Subsequently, deep silicon etching technology is applied to remove excess material, leaving behind the designed microstructure array. The back of the metasurface is manufactured in the same way.

[0021] The experimental resonance frequencies of the terahertz metasurface with double-sided sensing function provided by the present invention are 0.726 THz and 1.961 THz respectively. In order to further confirm the principle of double-sided quasi-bound states (QBICs), the electric field intensity of the metal structure in the XY axis plane is simulated: when the terahertz frequency is the excitation frequency of the front structure, the electric field intensity of the top surface is stronger than that of the back surface, indicating that at this frequency, the resonance array on the top surface is excited by the terahertz wave, and the resonance array on the back surface is not excited; on the contrary, when the frequency is adjusted to the operating frequency point of the back surface, the strong field confinement can only be detected on the back surface, but not on the front surface. The results show that the front and back sides of the metasurface can be excited by terahertz waves at the same time, generating double-sided QBICs with different frequencies, thereby realizing double-sided sensing function. The sensing performance of the double-sided metasurface provided by the present invention is comparable to that of the previously reported single-sided QBIC metasurface sensor, but it has double-sided sensing capability, which increases the sensing efficiency and can characterize the changes of two substances at the same time. In addition, the double-sided sensing is independent of each other and verifies each other during detection, which increases the accuracy and stability of ultra-sensitive sensing, showing broad application prospects in the field of biological detection.

[0022] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A terahertz metasurface biosensor with double-sided independent sensing function, characterized in that: include: The substrate is made of a material with high terahertz wave transparency and has a thickness of 100 µm; A first resonator array, integrated on the front side of the substrate, comprises a plurality of first resonators periodically arranged along the X-axis and the Y-axis of the substrate; the first resonator is an asymmetric split ring resonator, the first resonator has a circular ring body radius of 30 µm, a ring width of 5 µm, and an opening width of 5 µm; A second resonator array is integrated on the back side of the substrate, and includes a plurality of second resonators periodically arranged along the X-axis and the Y-axis of the substrate, wherein the second resonators are asymmetric open ring resonators, and the circular ring body radius of the second resonator is 17.5µm, the ring width is 3µm, and the opening width is 3µm.

2. The terahertz metasurface biosensor with double-sided independent sensing function according to claim 1, characterized in that: In the first resonator array, the distance between resonators is 20µm; In the second resonator array, the distance between resonators is 5µm.

3. The terahertz metasurface biosensor with double-sided independent sensing function according to claim 1, characterized in that: The resonance frequency of the first resonator array is 0.726 THz; the resonance frequency of the second resonator array is 1.961 THz.

4. The terahertz metasurface biosensor with double-sided independent sensing function according to claim 1, characterized in that: The substrate is made of quartz.

5. The terahertz metasurface biosensor with double-sided independent sensing function according to claim 1, characterized in that: The first resonator and the second resonator are made of gold with a thickness of 100 nanometers.

6. The terahertz metasurface biosensor with double-sided independent sensing function according to claim 5, characterized in that: A titanium layer is provided between the resonator and the substrate, and the thickness of the titanium layer is 10 nanometers.

7. The terahertz metasurface biosensor with double-sided independent sensing function according to claim 1, characterized in that: The asymmetric split ring resonator has two openings, which divide the annular body of the resonator into a semicircle and an arc.

8. According to any one of claims 1 to 7, the terahertz metasurface biosensor with double-sided independent sensing function, the integration method of the first resonator and the second resonator comprises: The substrate was treated with acetone solution and ultrasonically cleaned, rinsed with deionized water, and dried with nitrogen gas; Patterning the surface of the substrate using photolithography technology to form corresponding patterns of the first resonator array and the second resonator array; A 10-nanometer-thick titanium layer and a 100-nanometer-thick gold film are deposited on a substrate by magnetron sputtering, with the titanium layer located between the gold film and the substrate; Excess material is removed using deep silicon etching techniques, leaving the first resonator array and the second resonator array.

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