Terahertz metasurface biosensor
By designing a symmetrical open-loop resonant ring array structure, a strong local electromagnetic field resonance is excited, which solves the problem of insufficient sensitivity and accuracy of terahertz biosensors for detecting small biological molecules, and realizes high sensitivity and high accuracy detection of small biological molecules.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- BENGBU MEDICAL COLLEGE
- Filing Date
- 2026-03-13
- Publication Date
- 2026-05-12
AI Technical Summary
Existing terahertz biosensors have low refractive index responsiveness to small biological molecules, making it difficult to detect minute refractive index changes in low-concentration samples. Furthermore, conventional metasurface sensing units exhibit weak local electromagnetic field concentration effects, which reduces the signal-to-noise ratio and detection accuracy.
The metal functional layer, which adopts a symmetrical open resonant ring array structure, includes a left metal bar, a double-open rectangular ring, and a right metal bar. By vertically incident terahertz waves, a strong local electromagnetic field resonance is excited, which enhances the interaction between the local electromagnetic field and the biological sample and enables frequency shift measurement.
It achieves high sensitivity and high precision detection of small biological molecules, with a maximum sensitivity of 368 GHz/RIU, meeting the needs of trace detection and improving detection accuracy and signal-to-noise ratio.
Smart Images
Figure CN122016707A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of biosensor technology, and in particular to a terahertz metasurface biosensor. Background Technology
[0002] Terahertz waves (0.1 THz~10 THz) possess both the non-ionizing penetrating power of electromagnetic waves and the fingerprint spectral recognition characteristics of molecular vibrational / rotational modes, making them one of the important technical means in the field of label-free detection of biomolecules. However, current terahertz biosensors still face significant technical bottlenecks in practical applications: On the one hand, existing terahertz sensing structures generally have low refractive index responsivity to small biological molecules, making it difficult to capture minute refractive index changes caused by low-concentration samples and thus failing to meet trace detection requirements. On the other hand, conventional metasurface sensing units mostly employ a single resonant structure, resulting in a weak concentration effect of the local electromagnetic field, which weakens the signal-to-noise ratio and detection accuracy. Taking small biological molecules (such as glucose and amino acids) as an example, as core detection targets in medical diagnostics, food quality control, and biomedicine, traditional detection methods (such as electrochemical methods and fluorescent labeling methods) generally rely on chemical reagents, are susceptible to environmental interference, and are difficult to achieve label-free rapid detection. For example, one related study designed an asymmetric square split-ring resonator (SRR) array using a 500μm silicon substrate, successfully exciting an ultra-high Q-value resonant mode. By incident electric fields along the x-axis and y-axis respectively, this structure can generate quadrupole resonance and Fano resonance, with detection sensitivities reaching 23.9 GHz / RIU and 36.7 GHz / RIU respectively. Another related study proposed a ring-shaped terahertz metasurface composed of Chinese Taiji-shaped rings, with a sensitivity reaching 258 GHz / RIU.
[0003] Therefore, developing a terahertz metasurface biosensor that combines high sensitivity and high detection accuracy to achieve rapid, label-free, and high-precision detection of various small biological molecules has significant practical value. Summary of the Invention
[0004] The purpose of this application is to provide a terahertz metasurface biosensor that combines high sensitivity and high detection accuracy, enabling rapid, label-free, and high-precision detection of small biological molecules.
[0005] To achieve the above objectives, this application provides the following solution: This application provides a terahertz metasurface biosensor, which comprises multiple periodically arranged unit structures, each unit structure including a substrate layer and a metal functional layer; wherein, in any unit structure: The metal functional layer is deposited on the upper surface of the substrate layer, and the metal functional layer is a symmetrical open resonant ring array structure; The symmetrical open-ended resonant ring array structure includes: a left metal vertical bar, a double-opening rectangular ring, and a right metal vertical bar, wherein the left metal vertical bar and the right metal vertical bar are respectively disposed on both sides of the double-opening rectangular ring.
[0006] In one embodiment, the double-opening rectangular ring comprises two rectangular rings with openings facing each other.
[0007] In one embodiment, the opening width of each of the rectangular rings is 4 μm, the metal arm width of each of the rectangular rings is 6 μm, the width of the left metal strip and the width of the right metal strip are both 6 μm, and the width of the left metal strip and the length of the right metal strip are both 60 μm.
[0008] In one embodiment, the period of the unit structure is 80 μm.
[0009] In one embodiment, the substrate layer is made of polyimide.
[0010] In one embodiment, the thickness of the substrate layer is 30 μm.
[0011] In one embodiment, the relative permittivity of the substrate is 3.5, and the loss tangent of the substrate is 0.001.
[0012] In one embodiment, the metal functional layer is made of gold.
[0013] In one embodiment, the thickness of the metal functional layer is 0.2 μm.
[0014] In one embodiment, the electrical conductivity of the metal functional layer is 4.56 × 10⁻⁶. 7 S / m.
[0015] According to the specific embodiments provided in this application, this application has the following technical effects: This application discloses a terahertz metasurface biosensor, wherein the metal functional layer adopts a symmetrical open resonant ring array composed of a left-side metal vertical strip, a double-opening rectangular ring, and a right-side metal vertical strip. When a terahertz wave is incident perpendicularly, the metal functional layer undergoes strong resonant coupling with the electric field component of the terahertz wave, thereby exciting a highly concentrated local electromagnetic field on the surface of the unit structure, especially near the opening of the double-opening rectangular ring and the edge of the metal vertical strip. This effectively overcomes the deficiency of weak local field concentration effect in conventional single resonant structures. At the same time, due to the significant enhancement of this local electromagnetic field, when the biological sample to be tested covers the surface of the metal functional layer, the local field interacts strongly with the vibrational mode of the sample molecules, causing a significant shift in the resonant frequency of the metasurface. By detecting the frequency shift, high-precision measurement of the sample's refractive index change can be achieved. Attached Figure Description
[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] Figure 1 This is a schematic diagram of a terahertz metasurface biosensor structure provided in an embodiment of this application; Figure 2 This is a schematic diagram showing the relationship between D-anhydrous glucose solution with different refractive indices and resonant frequency, provided in an embodiment of this application. Detailed Implementation
[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0019] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0020] In one exemplary embodiment, a terahertz metasurface biosensor is provided, the terahertz metasurface biosensor comprising a plurality of periodically arranged unit structures, such as... Figure 1 As shown, each of the unit structures includes a base layer and a metal functional layer; wherein, in any unit structure: The metal functional layer is deposited on the substrate layer (i.e. Figure 1The upper surface of the blue area in the image, and the metal functional layer is a symmetrical open-loop resonant ring array structure (i.e., Figure 1 (The yellow area in the image).
[0021] The symmetrical open-ended resonant ring array structure includes: a left metal vertical bar, a double-opening rectangular ring, and a right metal vertical bar, wherein the left metal vertical bar and the right metal vertical bar are respectively disposed on both sides of the double-opening rectangular ring.
[0022] As an optional implementation method, such as Figure 1 As shown, the double-opening rectangular ring includes two rectangular rings with openings facing each other.
[0023] As an optional implementation method, such as Figure 1 As shown, the opening width of each of the rectangular rings is 4 μm (i.e., Figure 1 As shown in W3), the width of the metal arm of each of the rectangular rings is 6 μm (i.e. Figure 1 As shown in W1), the inner width of each of the rectangular rings is 10 μm (i.e., Figure 1 As shown in W4), the width of the left metal strip and the width of the right metal strip are both 6 μm (i.e. Figure 1 As shown in W2), the width of the left metal strip and the length of the right metal strip are both 60 μm (i.e. Figure 1 As shown in P2), the spacing between the rectangular ring and the metal vertical bars (including the right and left metal vertical bars) and between the rectangular rings is 4 μm (i.e. Figure 1 W5 is shown.
[0024] As an optional implementation, the period of the unit structure is 80 μm (i.e., Figure 1 P is shown.
[0025] As an optional implementation, the substrate layer is made of polyimide material, and the thickness of the substrate layer is 30 μm (i.e., Figure 1 As shown in P1), the relative permittivity of the substrate is 3.5, and the loss tangent of the substrate is 0.001. The substrate exhibits good terahertz wave transmission and mechanical stability.
[0026] As an optional implementation, the metal functional layer is made of gold, has a thickness of 0.2 μm, and has an electrical conductivity of 4.56 × 10⁻⁶. 7 S / m.
[0027] Specifically, the core function of the metallic functional layer is to enhance a strong localized field in the terahertz band. When a terahertz wave is incident perpendicularly, the geometry of the metal open-loop resonator resonates with the electric field component of the terahertz wave, creating a concentrated region of localized electromagnetic field on the surface of the unit structure. When the D-anhydrous glucose solution to be detected covers the surface of the metallic functional layer, the localized field couples with the vibrational modes of glucose molecules, causing a shift in the resonant frequency of the metasurface. By detecting the frequency shift, a highly sensitive measurement of the glucose refractive index can be achieved.
[0028] The resonant frequency of the D-anhydrous glucose solution is 1.5496 THz when the refractive index is 1.4; 1.5176 THz when the refractive index is 1.5; 1.4872 THz when the refractive index is 1.6; 1.4504 THz when the refractive index is 1.7; and 1.4168 THz when the refractive index is 1.7.
[0029] Furthermore, the sensitivity calculation formula is as follows: (1) in, Sensitivity, unit ; This is the resonant frequency offset, which is equal to the difference in resonant frequencies before and after the refractive index change. This represents the change in refractive index.
[0030] According to the sensitivity calculation formula, when the refractive index changes from 1.3 to 1.4, the sensitivity is: .
[0031] When the refractive index changes from 1.4 to 1.5, the sensitivity is: .
[0032] When the refractive index changes from 1.5 to 1.6, the sensitivity is: .
[0033] When the refractive index changes from 1.6 to 1.7, the sensitivity is: .
[0034] Thus, we can obtain the following: Figure 2 The graphs showing the relationship between D-anhydrous glucose solutions with different refractive indices and resonant frequencies are derived from... Figure 2As can be seen, the metasurface biosensor proposed in this application has a maximum detection sensitivity of 368 GHz / RIU, which fully demonstrates the excellent response characteristics of the metasurface biosensor to changes in medium concentration or refractive index.
[0035] The terahertz metasurface biosensor provided in this application enables label-free and rapid detection of trace amounts of small biomolecules such as glucose and tumor markers in blood and body fluids in the field of medical diagnostics, providing high-precision technical support for early diabetes screening and non-invasive cancer diagnosis. In the field of biomedical research and development, it can be used to monitor the interaction processes between biomolecules, providing a reliable detection tool for screening novel drug targets and studying molecular mechanisms. Furthermore, the stable response characteristics of the terahertz metasurface biosensor within the refractive index range of 1.3–1.7 give it the potential to be extended to more biological detection scenarios, and it also has significant application value in environmental monitoring and biosensor chip integration.
[0036] Beneficial effects: 1) The metal functional layer adopts a symmetrical open resonant ring array consisting of a left-side metal vertical bar, a double-opening rectangular ring, and a right-side metal vertical bar. When a terahertz wave is incident perpendicularly, the electric field component of the metal functional layer and the terahertz wave undergo strong resonant coupling, thereby exciting a highly concentrated local electromagnetic field on the surface of the unit structure (especially near the opening of the double-opening rectangular ring and the edge of the metal vertical bar), effectively overcoming the defect of weak local field concentration effect in conventional single resonant structures.
[0037] 2) Thanks to the enhancement of the local electromagnetic field, when the biological sample to be tested is covered on the surface of the metal functional layer, the local field interacts strongly with the vibration mode of the sample molecules, causing a significant shift in the resonant frequency of the metasurface. By detecting the frequency shift, the change in the refractive index of the sample can be accurately measured.
[0038] 3) Data analysis shows that the terahertz metasurface biosensor of this application has a maximum sensitivity of 368 GHz / RIU, which is a significant improvement compared to existing technologies (such as 23.9~36.7 GHz / RIU for asymmetric SRR structures and 258 GHz / RIU for taiji-shaped ring structures). It can effectively capture minute refractive index changes induced by low concentrations of small biological molecules, meeting the needs of trace detection.
[0039] 4) The substrate layer uses a low dielectric loss material. Combined with the optimized design of the above-mentioned symmetrical open resonant ring array, the energy loss of terahertz waves during transmission and resonance is effectively reduced, the signal-to-noise ratio of the sensing signal is improved, and the detection accuracy is further guaranteed.
[0040] In summary, this application achieves synergistic optimization of strong local field enhancement and high-sensitivity detection through a unique symmetrical open resonant ring structure, providing an effective technical solution for rapid, label-free, and high-precision detection of small biological molecules.
[0041] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0042] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the device and its core ideas. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.
Claims
1. A terahertz metasurface biosensor, characterized in that, The terahertz metasurface biosensor comprises multiple periodically arranged unit structures, each unit structure including a substrate layer and a metal functional layer; wherein, in any unit structure: The metal functional layer is deposited on the upper surface of the substrate layer, and the metal functional layer is a symmetrical open resonant ring array structure; The symmetrical open-ended resonant ring array structure includes: a left metal vertical bar, a double-opening rectangular ring, and a right metal vertical bar, wherein the left metal vertical bar and the right metal vertical bar are respectively disposed on both sides of the double-opening rectangular ring.
2. The terahertz metasurface biosensor according to claim 1, characterized in that, The double-opening rectangular ring comprises two rectangular rings with openings facing each other.
3. The terahertz metasurface biosensor according to claim 2, characterized in that, The opening width of each rectangular ring is 4μm, the metal arm width of each rectangular ring is 6μm, the width of the left metal strip and the width of the right metal strip are both 6μm, and the width of the left metal strip and the length of the right metal strip are both 60μm.
4. The terahertz metasurface biosensor according to claim 1, characterized in that, The period of the unit structure is 80 μm.
5. The terahertz metasurface biosensor according to claim 1, characterized in that, The base layer is made of polyimide.
6. The terahertz metasurface biosensor according to claim 1, characterized in that, The thickness of the substrate layer is 30 μm.
7. The terahertz metasurface biosensor according to claim 6, characterized in that, The relative permittivity of the substrate is 3.5, and the loss tangent of the substrate is 0.
001.
8. The terahertz metasurface biosensor according to claim 1, characterized in that, The metal functional layer is made of gold.
9. The terahertz metasurface biosensor according to claim 8, characterized in that, The thickness of the metal functional layer is 0.2 μm.
10. The terahertz metasurface biosensor according to claim 8, characterized in that, The electrical conductivity of the metal functional layer is 4.56 × 10⁻⁶. 7 S / m.