Terahertz metasurface biosensor with double-sided independent sensing function

Abstract

The utility model provides a terahertz metasurface biosensor with a double-sided independent sensing function, which relates to the technical field of biomedical detection and advanced materials, and comprises a substrate made of a material with high permeability to terahertz waves, and the thickness of the substrate is 100m; 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 utility model 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 utility model relates to biomedical detection technology and advanced material field, specifically, relate to a kind of terahertz super surface biosensor with double-sided independent sensing function. BACKGROUND

[0002] Terahertz (THz) wave is electromagnetic wave between infrared and microwave frequency band, and it shows great application potential in biomedical field due to its low photon energy, strong penetration ability and fingerprint spectrum response to various materials. However, due to insufficient terahertz radiation power and relatively mismatch between the measured substance and terahertz wavelength, the sensitivity of terahertz biosensing technology is limited. By combining terahertz technology with super surface technology, these challenges can be overcome. As a kind of artificial structure composed of subwavelength unit cells arranged periodically, super surface shows excellent performance in manipulating the phase, amplitude and polarization of electromagnetic wave, and the diverse resonance modes of super surface, such as dipole, Fano resonance and electromagnetic induced transparency (EIT), can produce highly localized strong electric field to enhance the interaction between light and matter. Among them, continuous domain bound state (BICs) has attracted widespread attention due to its ability to produce resonance with infinite quality (Q) factor. In theory, BICs, as stable intrinsic wave state, can capture light for infinite time, but its non-radiative property, i.e. disappearing spectral line width, limits its practical application. Through ingenious symmetry breaking, BICs can be transformed into quasi-bound state (QBICs) with limited radiation leakage, providing an important method for innovative design of high-Q factor optical devices. In the process of realizing the utility model, the applicant found that: the current research on QBICs implementation mainly focuses on single-sided etching microstructure of super surface to create enhanced local field confinement. This method only uses one side of the super surface, resulting in insufficient detection efficiency and single sensing result, which limits its potential for wider application in biosensing. Biological macromolecules have complex structure and high heterogeneity, and the contradiction between limited sensing efficiency and the need to characterize complex sensing signals is increasingly prominent, which brings great technical difficulties to the wide application of terahertz super surface biosensing. UTILITY MODEL CONTENT

[0003] The utility model aims at least to solve one of the technical problems existing in the prior art or related art, and provides a kind of terahertz super surface biosensor with double-sided independent sensing function, realizes terahertz super surface biosensor device with double-sided sensing function, and double-sided sensing is independent of each other, does not affect each other, so that the accuracy and efficiency of sensing are greatly improved.

[0004] The utility model discloses a kind of terahertz metasurface biological sensors with double-sided independent sensing function, comprising: substrate, made of material with terahertz wave high permeability, thickness is 100 µm;First resonator array, integrated on the front of substrate, including multiple first resonators periodically arranged along the X-axis and Y-axis of substrate;First resonator is asymmetric split ring resonator, the radius of annular main body of first resonator is 30 µm, annular width is 5 µm, opening width is 5 µm;Second resonator array, integrated on the back of substrate, including multiple second resonators periodically arranged along the X-axis and Y-axis of substrate, second resonator is asymmetric split ring resonator, the radius of annular main body of second resonator is 17.5 µm, annular width is 3 µm, opening width is 3 µm.

[0005] In the technical scheme, two-sided metasurface (the first resonator array is located on the front of substrate, and the second resonator array is located on the back of substrate) is constructed by two layers of different asymmetric split ring resonators (ASR), two independent QBICs are exhibited on both sides of the resonant structure of metal surface under the irradiation of THz wave based on the principle of quasi-continuous domain bound state (QBIC), and high sensitivity (169 GHz / RIU and 325 GHz / RIU, respectively) is achieved. The thickness of the substrate can not only avoid mutual coupling and interference of the two-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 biological sensor with double-sided independent sensing function provided by the utility model, preferably, in the first resonator array, the distance between resonators is 20 µm; in the second resonator array, the distance between resonators is 5 µm.

[0007] According to the terahertz metasurface biological sensor with double-sided independent sensing function provided by the utility model, preferably, the resonant frequency of the first resonator array is 0.726 THz; the resonant frequency of the second resonator array is 1.961 THz.

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

[0009] According to the terahertz metasurface biological sensor with double-sided independent sensing function provided by the utility model, preferably, the material of the first resonator and the second resonator is gold, and the thickness is 100 nanometers.

[0010] According to the terahertz metasurface biological sensor with double-sided independent sensing function provided by the utility model, preferably, a titanium layer is provided between the resonator and the substrate, and the thickness of the titanium layer is 10 nanometers.

[0011] The asymmetric split ring resonator has two openings, the openings divide the circular ring body of the resonator into a semicircle and an arc, and form an asymmetric structure.

[0012] According to the terahertz metasurface biosensor with double-face independent sensing function provided by the utility model, preferably, the integration method of the first resonator and the second resonator comprises: treating the substrate with an acetone solution and ultrasonic cleaning, rinsing with deionized water, and blowing dry with nitrogen; using a photolithography technology to pattern the surface of the substrate 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, with the titanium layer being located between the gold film and the substrate; using a deep silicon etching technology to remove excess material and leave the first resonator array and the second resonator array.

[0013] The utility model has at least the following beneficial effects: 100um thick quartz is selected as the substrate of the metasurface, which can make the double-face metal structure resonators not coupled with each other to achieve the function of double-face independent sensing, and can also reduce the loss of terahertz energy as much as possible to realize high sensing strength. The double QBIC peaks are realized, and the double BICs are independent of each other and can provide high sensing performance. The sensing performance of the double-face metasurface is equivalent to that of the single-face QBIC metasurface sensor reported previously, but the double-face metasurface has double-face sensing capability, increases the sensing efficiency, can simultaneously represent the changes of two substances, and the double-face sensing is independent of each other, which verifies each other during detection, increases the accuracy and stability of the ultra-sensitive sensing, and shows a broad application prospect in the field of biological detection. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 A front structure schematic diagram of the terahertz metasurface biosensor with double-face independent sensing function according to an embodiment of the utility model is shown.

[0015] Figure 2 An asymmetric split ring resonator monomer structure schematic diagram according to an embodiment of the utility model is shown.

[0016] Figure 3 A back structure schematic diagram of the terahertz metasurface biosensor with double-face independent sensing function according to an embodiment of the utility model is shown.

[0017] Figure 4 A perspective structure schematic diagram of the terahertz metasurface biosensor with double-face independent sensing function according to an embodiment of the utility model is shown. DETAILED DESCRIPTION

[0018] In order to more clearly understand the above purpose, features and advantages of the present application, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0019] As Figure 1 , Figure 2 and Figure 3 indicated, the embodiment of the present application discloses a terahertz metasurface biosensor with double-sided independent sensing function, comprising: a substrate 1 made of a material with high terahertz wave transparency, the thickness is 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 Y axis of the substrate, the arrangement period is P1=80µm; the first resonator is an asymmetric split ring resonator, the radius of the circular ring body of the first resonator is r1=30µm, the ring width is w1=5µm, and the opening width is d1=5µm; a second resonator array integrated on the back side (back side) of the substrate, comprising a plurality of second resonators 3 periodically arranged along the X axis and Y axis of the substrate, the arrangement period is P2=40µm; the second resonator is an asymmetric split ring resonator, the radius of the circular ring body of the second resonator is r2=17.5µm, the ring width is w2=3µm, and the opening width is d2=3µm.

[0020] As Figure 4 indicated, in this embodiment, the metasurface is carefully constructed by two layers of different asymmetric split ring resonators (ASR). The unit cell on the top side includes a semicircle with a radius of r1=30µm and a width of w1=5µm, and a circular arc, and the gap distance between the semicircle structure and the circular arc structure is d1=5µm. Each cell is a square periodically arranged along the X axis and Y axis, and the period is P1=80µm. The unit cell on the back side is reduced to nearly half the size of the top side in proportion, and the corresponding parameters are respectively marked as r2=17.5µm, w2=3µm, d2=3µm and p2=40µm.

[0021] According to another embodiment of the present application, a preparation method of the 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 acetone solution, ultrasonic cleaning, rinsed with deionized water, and dried with nitrogen. Then, the top surface of the substrate is patterned using photolithography technology, 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, a deep silicon etching technique is applied to remove excess material, leaving the designed microstructure array. The back of the metasurface is manufactured in the same way.

[0022] The experimental resonance frequency of the terahertz super surface with the double-sided sensing function is respectively 0.726 THz and 1.961 THz. In order to further confirm the principle of the double-sided quasi-bound state (QBIC), the electric field intensity of the metal structure in the X-Y 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, which indicates 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 working frequency point of the back surface, the strong field constraint can only be detected on the back surface, and the front surface cannot be detected. The results show that the front surface and the back surface of the super surface can be excited by the terahertz wave at the same time, and double-sided QBICs with different frequencies are generated, thereby realizing the double-sided sensing function. The sensing performance of the double-sided super surface provided by the utility model is equivalent to the single-sided QBIC super surface sensor performance reported previously, but it has the double-sided sensing function, increases the sensing efficiency, can simultaneously represent the changes of two substances, and the double-sided sensing is independent of each other, verifies each other during detection, increases the accuracy and stability of the super-sensitive sensing, and shows a broad application prospect in the field of biological detection.

[0023] The above only describes preferred embodiments of the utility model, and is not used for limiting the utility model, for the person skilled in the art, the utility model can have various changes and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model should be included in the protection scope of the utility model.

Claims

1. A terahertz metasurface biosensor with double-sided independent sensing function, characterized in that, Comprising: a substrate made of material with high transmittance of terahertz wave, thickness of 100 µm; a first resonator array integrated on the front surface of the substrate, comprising a plurality of first resonators arranged periodically along the X and Y axes of the substrate; the first resonator is an asymmetric split ring resonator, the radius of the circular ring body of the first resonator is 30 µm, the width of the ring is 5 µm, and the width of the split is 5 µm; a second resonator array integrated on the back surface of the substrate, comprising a plurality of second resonators arranged periodically along the X and Y axes of the substrate, the second resonator is an asymmetric split ring resonator, the radius of the circular ring body of the second resonator is 17.5 µm, the width of the ring is 3 µm, and the width of the split is 3 µm.

2. The THz 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 20 µm; In the second resonator array, the distance between resonators is 5 µm. 3.The THz metasurface biosensor with double-sided independent sensing function according to claim 1, wherein, The resonant frequency of the first resonator array is 0.726 THz; the resonant frequency of the second resonator array is 1.961 THz.

4. The THz metasurface biosensor with double-sided independent sensing function according to claim 1, characterized in that, The substrate is made of quartz. 5.The THz metasurface biosensor with double-sided independent sensing function according to claim 1, wherein, The material of the first resonator and the second resonator is gold, and the thickness is 100 nanometers.

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

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