Terahertz Rydberg atomic system-oriented high-sensitivity biosensing enhanced metamaterial chip design

Abstract

The invention relates to a high-sensitivity biosensing enhanced metamaterial chip for a terahertz Rydberg atomic system. The metamaterial chip with enhanced sensing and continuously tunable response frequency is designed in a targeted manner mainly based on response frequency point characteristics of a terahertz Rydberg atomic system. The chip unit is composed of four groups of orthogonally distributed broken line type metal microstructures, a centrosymmetric ring-like structure layout is adopted, a local electromagnetic field is enhanced by regulating and controlling surface current distribution, and the working frequency of the chip unit can be tuned according to an actual terahertz Rydberg atomic system response frequency point. In addition, geometrical characteristics of the chip are realized through a silicon substrate-metal composite technology, characteristics such as low-frequency point position and local enhancement are realized through optimization of chip period parameters and capacitor gap and inductor layout, and through synergistic effect of the chip and a Rydberg atom detection system, the detection precision of the chip is improved. The detection efficiency and accuracy of trace biological samples placed on the surface of the metamaterial chip can be greatly improved, and the sensitivity is improved by three orders of magnitude compared with that of a traditional TDS system. The metamaterial chip for the terahertz Rydberg atomic system provided by the invention has the characteristics of quick response, high sensitivity, tunable frequency and the like, realizes miniaturized structural design through a microstructure processing technology, and can adapt to various detection requirements and wide application scenes.

Description

Technical Field

[0001] The present invention relates to a terahertz Rydberg atom detection technology, and in particular to a highly sensitive biosensing enhanced metamaterial chip design for a terahertz Rydberg atom system. Background Art

[0002] Terahertz waves, electromagnetic radiation with a frequency between 0.1 and 10.0 THz, possess multiple unique physical properties: their high signal-to-noise ratio enables weak signal detection, their strong penetrating power allows for structural analysis of non-metallic media, their low photon energy and non-ionization ensure non-destructive testing of biological samples, their wide spectrum supports multi-band composite applications, and their excellent spatiotemporal coherence facilitates wavefront manipulation. Furthermore, in the biomedical field, the vibrational frequencies corresponding to weak interaction energy levels between biomacromolecules, as well as characteristic modes such as protein backbone torsional vibrations and DNA base pair breathing vibrations, all fall precisely within the terahertz frequency band. Based on this, terahertz time-domain spectroscopy can fingerprint molecular conformations through characteristic absorption peaks, and combined with dielectric relaxation spectrum analysis, it can analyze the dynamic assembly process of biomolecules.

[0003] However, traditional terahertz detection technology faces fundamental physical limitations in biomedical trace analysis. Constrained by the diffraction limit of classical electromagnetic field-matter interactions, the detection sensitivity of low-level biomarkers such as circulating tumor DNA has long been limited, and it is unable to break through the femtomolar (fmol) threshold required for early cancer diagnosis. The development of quantum sensing technology has opened up a new path to break through this bottleneck. Highly excited Rydberg atoms have giant electric dipole moments on the order of μB and millimeter-level orbital radii. Through chip-based quantum sensing architecture, the problem of limited detection sensitivity in traditional free-space systems can be effectively overcome. This technology uses electromagnetically induced transparency (EIT) spectroscopy to achieve field strength measurement traceable to quantum standards, providing a new approach for detecting weak interactions in biomolecules.

[0004] However, current high-sensitivity terahertz sensor chips have obvious design limitations. On the one hand, mainstream chips are based on photonic crystals and plasma resonance mechanisms, and their structural dimensions do not match the wavelength. As a result, the subwavelength unit structure is weakened due to the local effect of the electromagnetic field, making it difficult to stimulate effective resonance. Therefore, the operating frequency of mainstream chips is mostly concentrated in the high-frequency band of 1.0-5.0THz, and the proportion of low-frequency chips is insufficient. On the other hand, in order to meet the resonance frequency requirements, existing metamaterial chips generally adopt the method of amplifying the periodic structure of the unit. The unit structure size of the low-frequency chip reaches about 500μm. Under ideal circumstances, the conventional terahertz spot in the Rydberg system has a diameter of 2.5mm and an area of 19mm. 2, it is necessary to ensure that approximately 2,500 chip units are covered within the light spot area to improve efficiency. This results in the light spot covering too few chip units during actual testing, significantly reducing the effect on biological samples. The contradiction between the two lies in the increase in the unit size at the low-frequency resonance position that meets the wavelength matching requirement, which is inconsistent with the requirement for the number of chip units covered by the light spot. These aspects directly reflect the current lack of practical metamaterial chips that have both low-frequency response and meet the light spot coverage requirements, limiting their application in scenarios such as high-sensitivity biological detection and sample analysis. The present invention is based on the principles of dipole resonance and local field enhancement. While meeting the requirements for the number of chip units covered by the terahertz spot, combined with the Rydberg atom detection system, it innovatively proposes a terahertz metamaterial sensor chip suitable for low frequencies (0.1-1.0 THz). Through a specially designed subwavelength resonant structure, it captures the changes in the dielectric properties of biological samples and converts them into measurable terahertz frequency domain characteristic peak shifts, achieving the synergistic effect of quantum mixing noise suppression and metamaterial subwavelength field localization, and improving the detection sensitivity by three orders of magnitude compared to traditional TDS systems. Summary of the Invention

[0005] To address the limited sensitivity of terahertz biosensing technology in low-frequency molecular detection and the insufficient number of light source coverage units, this paper proposes a highly sensitive biosensing enhanced metamaterial chip design based on a terahertz Rydberg atom system. By constructing a zigzag metal resonant microstructure within a silicon-based composite metamaterial chip and utilizing a synergistic control mechanism of dipole resonance and local electromagnetic field enhancement, a sensor-enhanced chip was constructed that simultaneously meets the required number of light source coverage units in the low-frequency range of 0.1-1.0 THz. The core technology lies in utilizing the local field enhancement effect of the periodic resonant structure to enhance the interaction strength between biological particles and terahertz waves. Combining a mode coupling optimization design with the synergistic Rydberg atom detection system, this technology achieves high-sensitivity detection that is three orders of magnitude higher than traditional TDS systems.

[0006] The technical solution of the present invention is: a highly sensitive biosensor enhanced metamaterial chip for terahertz Rydberg atomic systems, which is composed of a periodic metamaterial array on a silicon dielectric substrate, and each unit contains a centrally symmetrically arranged zigzag metal resonant structure, showing a cross-arranged polygonal feature. For the selection of metal materials, we use the dielectric constant ε and the magnetic permeability μ as key indicators to measure electromagnetic properties. The dielectric constant ε is used to quantitatively describe the strength of the polarization phenomenon produced by the material under the action of an electric field. The larger the value of the dielectric constant ε, the higher the sensitivity of the internal charge of the material to the electric field, that is, the stronger the polarization response. The magnetic permeability μ is a magnetic parameter that measures the material's ability to respond to magnetization in a magnetic field. The higher the magnetic permeability μ, the easier it is for the magnetic moment inside the material to produce a cooperative orientation with the external magnetic field, thereby showing a stronger magnetization effect. Based on this theoretical basis, we introduced the LC resonance principle, and its resonance frequency calculation formula is: The inductance capacitance μ0 is the vacuum permeability, μ r is the relative magnetic permeability of the base material, t is the metal thickness, ∈ eff is the effective dielectric constant of the object under test and the substrate, l is the arm length, A is the effective area of the capacitor plates, and W is the width of the capacitor gap. During the design process, we needed to ensure a coordinated match between the frequency of the terahertz wave emitted by the terahertz source module, the resonant frequency of the biosensor metamaterial chip, the characteristic absorption frequency of the biological sample, and the response frequency corresponding to the detection energy level set by the Rydberg detection module. Furthermore, by adjusting and modifying the properties and external structure of the metal material, the metamaterial chip was able to adapt to the resonance requirements at different target frequencies, achieving a highly sensitive response to trace dielectric perturbations at the resonant frequency.

[0007] The structure's inductance is generated by the zigzag metal arms, while the capacitance is achieved through two submicron-level gaps in the diagonal direction. The length, thickness, and gap width of the zigzag metal arms can be optimized to achieve control over various aspects, such as the resonant frequency position and bandwidth.

[0008] The dielectric substrate material in the metamaterial unit includes but is not limited to dielectric materials such as silicon, quartz, and polyimide.

[0009] The structure is preferably made of high-conductivity metal materials such as copper, gold, and aluminum, including but not limited to the above materials, to ensure equivalent medium response at the target frequency band.

[0010] The chip parameters can be adjusted (such as period, thickness and arm length) to adapt to multiple frequency bands such as microwave, far infrared and mid-infrared, and achieve sensing enhancement at specific frequencies while maintaining the basic configuration unchanged.

[0011] The terahertz Rydberg atom system is composed of a terahertz source module, a biosensor metamaterial chip, a Rydberg detection module, and a data processing and display module, which are sequentially placed along the same optical axis. The spectral range of the terahertz source must cover and exceed the operating frequency band of the sensor. First, the biosensor metamaterial chip is fixed on the sample holder and aligned with the polarization direction of the terahertz wave emitted by the terahertz source module. Secondly, the Rydberg detection module detects and records the inherent resonance peak spectrum of the biosensor metamaterial chip, and transmits the data to the data processing and display module. After processing, the LC coupling and dipole resonance peaks can be obtained. Next, the sample solution is dripped onto the array structure on the surface of the biosensor metamaterial chip. After it dries and forms a film, the sensor spectrum changes of the biosensor metamaterial chip are detected and recorded again. Finally, by comparing the two transmission spectra and reading the frequency offset and amplitude change before and after the resonance peak, the content of each component in the biological sample can be determined.

[0012] The frequency of the terahertz wave emitted by the terahertz source module, the resonance frequency of the biosensor metamaterial chip, the characteristic absorption frequency of the biological sample, and the response frequency corresponding to the detection energy level set by the Rydberg detection module must be exactly the same for the system to respond and detect.

[0013] The frequency of the terahertz wave emitted by the terahertz source module can be adjusted according to the characteristic peak of the biological sample to be detected.

[0014] The detection energy level of the Rydberg detection module can be adjusted according to the characteristic peak of the biological sample to be detected.

[0015] The beneficial effects of the present invention are: a highly sensitive biosensing enhanced metamaterial chip design based on a terahertz Rydberg atom system is proposed, and a solution is provided for the problems of limited sensitivity and insufficient number of light spot coverage units in low-frequency molecular detection of terahertz biosensing technology. By designing a broken-line metal resonant microstructure on a silicon substrate, dipole resonance and local electromagnetic field enhancement effects are achieved in the low-frequency band (0.1-1.0THz) terahertz. At the same time, by optimizing the number of light spot coverage chip units and combining the Rydberg atom detection system, an innovative synergistic effect of noise suppression of quantum mixing and subwavelength field localization of metamaterials is proposed, and the detection sensitivity is improved by three orders of magnitude compared to the traditional TDS system. In addition, the present invention adopts a micron-level standardized processing technology and realizes mass production of metamaterial chips based on mature semiconductor manufacturing processes, which significantly reduces manufacturing costs and ensures process stability, and has good reusability. Moreover, the size parameters of the structure can be scaled to suit different frequency bands, and it has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1This is a schematic diagram of the unit structure of the highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems of the present invention;

[0017] Figure 2 Schematic diagram of the highly sensitive biosensing enhanced metamaterial chip array for terahertz Rydberg atom systems of the present invention;

[0018] Figure 3 Schematic diagram of the highly sensitive biosensing enhanced metamaterial chip detection system for terahertz Rydberg atom systems of the present invention;

[0019] Figure 4 This is the simulated transmission spectrum of the highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems of the present invention;

[0020] Figure 5 This is the simulated transmission spectrum of melanin (ε=2.5) in the highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems of the present invention;

[0021] Figure 6 This is a schematic diagram of the structure of the highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems of the present invention.

[0022] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0023] like Figure 1 、 2 As shown, the core functional layer of the biosensing metamaterial chip is composed of a dielectric substrate 1 and a metal resonator array 2. The surface of the structure is formed by ordinary photolithography technology, using metal copper as the material to form a periodic metal microstructure array to achieve the modulation and enhancement of terahertz waves. Each resonant unit is composed of four zigzag metal arms. This unique geometric design gives the resonant unit excellent electromagnetic properties. Its free electron concentration can excite collective oscillations of the surface plasma and achieve wave vector matching through subwavelength local resonance effects. When the terahertz wave is incident, it can excite multimodal electromagnetic resonance on this path. We explain the position of the resonant frequency by introducing the LC resonance principle, and its calculation formula is: The inductance capacitance μ0 is the vacuum permeability, μ r is the relative magnetic permeability of the base material, t is the metal thickness, ∈ effis the effective dielectric constant of the DUT and substrate, l is the arm length, A is the effective area of the capacitor plates, and W is the capacitor gap width. Based on this, the chip structural parameters are optimized through electromagnetic simulation to ensure that the plasmons on the chip surface at the target frequency meet wave vector matching, allowing the various resonant units to interact effectively and form a synergistic electromagnetic effect.

[0024] like Figure 3 As shown in the figure, the detection system adopts a coaxial optical path design, including a terahertz source module 1, a biosensor 2, a Rydberg detection module 3, and a data processing module 4. This design makes the optical path alignment between the various functional modules more convenient and accurate, and improves the overall performance and stability of the system. In detail, the core architecture of the experimental system is based on a three-step stepped infrared laser excitation (wavelength 852nm / 1470nm / 785nm), which first coherently excites the cesium atoms to the Rydberg state. On this basis, the system adopts a dual terahertz field (including: signal field and local oscillator field, Figure 3 The superheterodyne detection scheme (represented by a unified terahertz source module) uses a frequency mixing scheme: the local oscillator field establishes a resonant transition with the Rydberg atoms, while the signal field, after being enhanced by the local field of the metamaterial chip, interacts with the biological sample. The terahertz absorption signal of the biological sample is converted into a resolvable spectrum signal through a quantum mixing process, enabling highly sensitive detection of molecular properties and qualitative and quantitative analysis of the sample. This integrated data processing approach significantly improves the intelligence and efficiency of the detection system, increasing detection sensitivity by three orders of magnitude compared to traditional TDS systems.

[0025] like Figure 4 The figure shows the simulated transmission spectrum of a 100×100 array of pure copper resonant structures constructed on the surface of a dielectric substrate. The unit size is 100×100μm. 2 The line width is 4μm, and the gap width is 2μm. The finite-difference time-domain method can accurately simulate the propagation and scattering characteristics of electromagnetic waves in complex structures. The calculation shows that a dipole resonance peak appears at 345GHz. The appearance of this resonance peak verifies the rationality of the resonant structure design and the excellent electromagnetic performance.

[0026] Attachment Figure 5 The simulated transmission spectrum after loading melanin molecules (ε=2.5) is shown. When the resonance frequency shifts to the low frequency direction for detection, the resonance frequency of the sensor without sample loading is 345 GHz (see Appendix Figure 4 ), the frequency shifted to 307 GHz after loading the water-soluble melanin sample (ε=2.5) ( Figure 5), verifying the effectiveness of the frequency shift detection mechanism. These changes demonstrate the physical correlation between molecular dielectric perturbations and altered resonance properties. When biomolecules are loaded onto a resonant structure, their dielectric properties affect the electromagnetic properties of the resonant structure, resulting in a shift in the resonant frequency and changes in the half-width of the absorption peak. This physical correlation provides a theoretical basis for biosensing, enabling the detection of biomolecules by detecting changes in resonance properties.

[0027] 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 patent. 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 patent for this invention shall be determined by the appended claims.

Claims

1. A highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems, characterized by: It consists of a periodic metamaterial array on a silicon dielectric substrate. Each unit contains a centrally symmetrically arranged zigzag metal resonant structure, presenting a cross-arranged polygonal feature. The overall structure adopts a composite structure of silicon-based substrate and metal metamaterial.

2. The highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems according to claim 1, characterized in that: The inductance portion of the structure is generated by the zigzag metal arm, and the capacitance portion is realized by two submicron-level gaps in the diagonal direction. The length, thickness and gap width of the broken-line metal arm can be optimized according to actual requirements to achieve various adjustments such as the position of different resonance frequencies and bandwidths.

3. The highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems according to claim 1, characterized in that: The dielectric substrate material in the metamaterial unit includes but is not limited to dielectric materials such as silicon, quartz, and polyimide.

4. The highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems according to claim 1, characterized in that: The structure is preferably made of high-conductivity metal materials such as copper, gold, and aluminum, including but not limited to the above materials, to ensure equivalent medium response at the target frequency band.

5. The highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems according to claim 1, characterized in that: By adjusting the scaling ratio of key design parameters (such as period, thickness and arm length), the structure can be adapted to multiple frequency bands such as microwave, far infrared and mid-infrared, and achieve sensing enhancement at specific frequencies while maintaining the basic configuration unchanged.

6. The highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems according to claim 1, characterized in that: In a terahertz Rydberg atom system, a terahertz source module, a biosensor metamaterial chip, a Rydberg detection module, and a data processing and display module are placed sequentially along the same optical axis. The spectral range of the terahertz source must cover and exceed the operating frequency band of the sensor. First, the biosensor metamaterial chip is fixed to the sample holder and aligned with the polarization direction of the terahertz wave emitted by the terahertz source module. Next, the Rydberg detection module detects and records the intrinsic resonance peak spectrum of the biosensing metamaterial chip. This data is then transmitted to the data processing and display module, where it is processed to obtain the LC coupling and dipole resonance peaks. Next, the sample solution is dripped onto the array structure on the surface of the biosensing metamaterial chip. After drying to form a film, the sensor spectrum changes of the biosensing metamaterial chip are again detected and recorded. Finally, by comparing the two transmission spectra and reading the frequency offset and amplitude change before and after the resonance peak, the content of each component in the biological sample can be determined.

7. The highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems according to claim 1, characterized in that: The frequency of the terahertz wave emitted by the terahertz source module, the resonance frequency of the biosensor metamaterial chip, the characteristic absorption frequency of the biological sample, and the response frequency corresponding to the detection energy level set by the Rydberg detection module must be exactly the same for the system to respond and detect.

8. The highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems according to claim 1, characterized in that: The frequency of the terahertz wave emitted by the terahertz source module can be adjusted according to the characteristic peak of the biological sample to be detected.

9. The highly sensitive biosensing enhanced metamaterial chip for terahertz Rydberg atom systems according to claim 1, characterized in that: The detection energy level of the Rydberg detection module can be adjusted according to the characteristic peaks of the biological sample to be detected.

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