Trace biochemical sensor based on deep sub-wavelength singular point resonance

Abstract

The invention discloses a trace biochemical sensor based on deep sub-wavelength singular point resonance, the sensor comprises an upper metal layer, a middle dielectric layer and a lower metal layer which are stacked in sequence from top to bottom, the upper metal layer is a deep sub-wavelength singular point resonance structure pattern, the lower metal layer is an excitation microstrip line, and the middle dielectric layer is a deep sub-wavelength singular point resonance structure pattern. Resonance of the deep sub-wavelength singular point resonance structure pattern is excited by the excitation microstrip line. By effectively adjusting the rotation angle of the deep sub-wavelength singular point resonance structure graph, the resonance mode field of the sensor is gradually evolved into a singular point resonance mode from a hybrid bonding and anti-bonding intrinsic resonance mode. According to the sensor, the equivalent working wavelength of the deep sub-wavelength artificial local surface plasmon resonance unit is compressed, and the electromagnetic field enhancement characteristic of a singular point resonance mode and the square root dependency relationship of tiny dielectric disturbance are combined, so that the high-sensitivity resolution of trace biochemical quantity is realized in a low-frequency microwave band.

Description

Technical Field

[0001] The invention relates to a trace biochemical sensor, in particular to a trace biochemical sensor based on deep subwavelength singular point resonance. Background Art

[0002] Microwave resonant sensors can realize flexible and diverse physical and biochemical sensing functions by detecting the resonant frequency shift and resonant splitting signals caused by changes in the dielectric constant of the surrounding environment. They have advantages such as real-time sensing detection capability and environmental adaptability. In addition, microwave resonant sensors are highly compatible with planar circuits and are expected to develop miniaturized sensing detection circuits or detection systems for the Internet of Everything. However, due to the long microwave wavelength, microwave resonant sensors are difficult to meet the actual needs of trace biochemical quantity sensing.

[0003] At present, there are two effective solutions to achieve trace biochemical quantity sensing in the microwave long-wave band: one is based on the deep subwavelength binding ability of artificial localized surface plasmons and the high sensitivity improvement corresponding to the equivalent wavelength; the other is based on the square root dependence of the resonant splitting of the singular point on the disturbance intensity, which greatly enhances the detection sensitivity of trace biochemical quantity sensing. However, existing sensing technologies are limited to the subwavelength scale, often requiring a large integration area, and the sensing signal is significantly interfered by noise, which greatly limits the sensing resolution.

[0004] Deep subwavelength structures usually have extremely high structural robustness, and it is difficult to achieve singularities through external scatterer interference or simple structural parameter adjustment; in addition, it is extremely difficult to accurately control the spatial distribution of system gain and loss at the deep subwavelength scale; finally, since the deep subwavelength resonant structure is at a quasi-static scale, its high insensitivity to phase changes also limits the possibility of achieving singularities through phase control schemes. Summary of the invention

[0005] In view of the problems existing in the prior art, the object of the present invention is to provide a trace biochemical sensor based on deep subwavelength singular point resonance.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A trace biochemical sensor based on deep subwavelength singular point resonance comprises an upper metal layer, an intermediate dielectric layer and a lower metal layer stacked in sequence from top to bottom, wherein the upper metal layer is a deep subwavelength singular point resonance structure pattern, the lower metal layer is an excitation microstrip line, and the resonance of the deep subwavelength singular point resonance structure pattern is excited by the excitation microstrip line.

[0008] Furthermore, the deep subwavelength singular point resonance structure pattern is specifically a resonance structure formed by coupling two identical deep subwavelength metal resonance units, and the deep subwavelength singular point resonance structure pattern supports two hybridized intrinsic resonance modes.

[0009] Furthermore, the singular point resonance in the deep subwavelength singular point resonance pattern is formed by coupling of two hybridized intrinsic resonance modes, and is coupled and regulated by the excitation microstrip line.

[0010] Furthermore, the artificial localized surface plasmon resonance unit is specifically an Archimedean spiral metal wire.

[0011] Furthermore, the coupling regulation is achieved by exciting the relative rotation of the microstrip line and the deep subwavelength singular point resonant structure pattern.

[0012] A trace biochemical sensing detection method comprises the following steps:

[0013] Connect the two ends of the above sensor to SMA connectors respectively, and connect the two SMA connectors to the vector network analyzer through coaxial cables;

[0014] Using a microsyringe to drop a drop of the biochemical quantity to be measured on the sensor;

[0015] Observe the transmission spectrum detected in the vector network analyzer. When frequency splitting is observed, it means that contact real-time sensing detection of the biochemical quantity droplet to be measured is achieved.

[0016] Compared with the prior art, the present invention has the following beneficial effects: a trace biochemical sensor based on deep subwavelength singular point resonance disclosed in the present invention utilizes the strong evanescent field coupling between two identical artificial localized surface plasmon resonance units to construct two hybrid modes of bonding and anti-bonding; by effectively adjusting the geometric parameters of the coupled resonance, the two hybrid modes produce an extremely strong coupling effect, thereby realizing the singular point resonance mode. Compared with the existing sensing technology, the deep subwavelength singular point mode realized in the present invention proposes a new mechanism for realizing singular points at the deep subwavelength scale, and this innovative theory is also applicable to other deep subwavelength electromagnetic resonance systems. The present invention achieves high-sensitivity resolution of trace biochemical quantities in the low-frequency microwave band by compressing the equivalent working wavelength of the deep subwavelength artificial localized surface plasmon resonance unit and combining the electromagnetic field enhancement characteristics of the singular point resonance mode and the square root dependence on tiny dielectric perturbations. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of the trace biochemical sensor based on deep subwavelength singular point resonance provided by the present invention, (a) is a front schematic diagram, and (b) is a back schematic diagram;

[0018] Figure 2 It is a schematic diagram of the principle of the trace biochemical sensor based on deep subwavelength singular point resonance provided by the present invention;

[0019] Figure 3 In the trace biochemical sensor based on deep subwavelength singular point resonance provided by the present invention, the transmission spectrum (S 21 )evolution;

[0020] Figure 4 A distribution diagram of the electric field z component of the bonding mode, anti-bonding mode and singular point resonance mode in the trace biochemical sensor based on deep subwavelength singular point resonance provided by the present invention;

[0021] Figure 5 The sensitivity comparison between the trace biochemical sensor based on deep subwavelength singular point resonance provided by the present invention and the traditional deep subwavelength sensor, (a) is the present invention, (b) is the traditional deep subwavelength sensor;

[0022] Figure 6 This is an experimental schematic diagram of nanomole glucose droplet sensing detection using a trace biochemical sensor based on deep subwavelength singular point resonance provided by the present invention;

[0023] Figure 7 The experimental results of nanomolar glucose droplet sensing detection by the trace biochemical sensor based on deep subwavelength singular point resonance provided by the present invention, (a) is the scatter mean, error bar and nonlinear fitting graph of the resonance frequency splitting changing with glucose concentration, (b) is the scatter mean, error bar and nonlinear fitting graph of the low-frequency resonance frequency changing with glucose concentration. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0025] The embodiment of the present invention provides a trace biochemical sensor based on deep subwavelength singular point resonance, such as Figure 1As shown, it includes an upper metal layer, an intermediate dielectric layer and a lower metal layer stacked in sequence from top to bottom, the upper metal layer is a deep subwavelength singular point resonance structure pattern, the lower metal layer is an excitation microstrip line, and the resonance of the deep subwavelength singular point resonance structure pattern is excited by the excitation microstrip line. The deep subwavelength singular point resonance structure pattern is specifically a resonance structure formed by coupling two identical deep subwavelength metal resonance units, and the coupling points of the two deep subwavelength metal resonance units are located at the symmetry center of the intermediate dielectric layer and the excitation microstrip line. The deep subwavelength metal resonance unit is specifically an artificial localized surface plasmon resonance unit, such as an Archimedean spiral metal line. The deep subwavelength singular point resonance structure pattern supports two hybrid resonance modes. The singular point resonance of the deep subwavelength singular point resonance structure pattern is formed by coupling two hybrid resonance modes, which are coupled and regulated by the excitation microstrip line, specifically by the relative rotation of the excitation microstrip line and the deep subwavelength singular point resonance structure pattern.

[0026] The intermediate dielectric layer is any one of FR4, F4B, RO4003, 3003, 4350, RT5880, 5870, 6002, 6006, 6010, 6035, 6202 produced by Rogers, N4000-13, N4000-13EPSI printed circuit and microwave circuit dielectric substrates produced by Nelco, or a semiconductor or dielectric of any one of Si, SiO2, Al2O3, GaAs, and GaN, or a flexible organic dielectric; the thickness of the intermediate dielectric layer is between 10nm and 10mm.

[0027] The material of the upper metal layer and the lower metal layer is any single material or any composite material of copper, tin, gold, silver, chromium, lead, platinum, zinc, aluminum, magnesium, and titanium; the thickness of the upper metal layer and the lower metal layer are both between 5nm and 1mm.

[0028] The principle schematic diagram of the present invention is as follows Figure 2 As shown, when a signal is input into the excitation waveguide and the rotation angle of the deep subwavelength singular point resonant structure pattern is adjusted, the strong coupling between the two hybrid modes of bonding and anti-bonding supported in the deep subwavelength singular point resonant structure pattern can be adjusted, thereby realizing the singular point resonant mode at the deep subwavelength scale.

[0029] Figure 3 In order to realize the transmission spectrum (S) of the singular point process by adjusting the rotation angle of the deep subwavelength singular point resonant structure pattern, 21) evolution. It can be clearly observed in the transmission spectrum that with the change of the rotation angle, when the rotation angle α is 39°, the split resonances of the bonding mode and the anti-bonding mode merge into a single resonance at the singular point. At the same time, the square root dependence of the frequency detuning amount and the rotation angle in the process of adjusting the singular point also verifies the formation of a singular point in the deep subwavelength singular point resonance structure diagram.

[0030] Figure 4 The distribution diagram of the electric field z component of the bonding mode, anti-bonding mode and singular point resonance mode in the sensor of the present invention, wherein the two artificial localized surface plasmon units of the bonding mode have the same resonance polarity, and the two artificial localized surface plasmon units of the anti-bonding mode have opposite resonance polarities. At the singular point resonance mode, it can be observed that the mode field of one of the artificial localized surface plasmon resonance units is almost completely suppressed, and is completely localized in the other artificial localized surface plasmon resonance unit, accompanied by an electromagnetic field enhancement effect.

[0031] Figure 5 The sensitivity comparison between the sensor of the present invention and the traditional deep sub-wavelength sensor is shown in FIG. Figure 5 (a) is the sensitivity of the sensor of the present invention, and the sensing signal is the frequency splitting amount of the splitting resonance peak. As the relative dielectric constant of the medium to be measured increases, the resonant frequency of the high-frequency resonance mode hardly changes, while the resonant frequency of the low-frequency resonance mode shifts toward the low frequency, so the resonance splitting gradually increases; Figure 5 (b) is a traditional deep subwavelength sensor. The sensing signal is the frequency shift of a single resonance peak. As the relative dielectric constant of the medium to be measured increases, the resonance frequency gradually shifts to a low frequency. It can be seen from the normalized resonance frequency that the sensitivity of the trace biochemical sensor based on deep subwavelength singular point resonance is significantly improved compared to the traditional deep subwavelength sensor.

[0032] The present invention also provides a trace biochemical sensing detection method. Figure 6 As shown, the following steps are included:

[0033] Connect the two ends of the above sensor to SMA connectors respectively, and connect the two SMA connectors to a vector network analyzer through coaxial cables; the vector network analyzer may be a Keysight E5063A vector network analyzer;

[0034] Using a microsyringe to drop a drop of a biochemical quantity to be measured on the sensor; wherein the biochemical quantity to be measured is any one of a solution, an antigen, an antibody, an exosome, a bacterium, and a cell;

[0035] Observe the transmission spectrum detected in the vector network analyzer. When frequency splitting is observed, it means that contact real-time sensing detection of the biochemical quantity droplet to be measured is achieved.

[0036] The present invention is experimentally verified below. The geometric parameters of the sensor structure used in the experiment are: α=39°, d=0.1mm, g=0.15mm; the equations of the Archimedean spiral are x=r·t·cos(t), y=r·t·cos(t), where r=0.05, and t varies from 0 to 20π; the lower metal layer is a 50-ohm microstrip line with a strip width of w=1.34mm; according to the resonant wavelength of the singular point resonance mode and the diameter of the artificial localized surface plasmon resonance unit, it can be obtained that the resonance mode confines the electromagnetic field to within 1 / 50 of the wavelength, thereby achieving a great compression of the equivalent working wavelength; the dielectric constant of the intermediate dielectric layer is 2.65, and the loss tangent value is 0.001.

[0037] according to Figure 6 When a fixed volume of a micro droplet of the to-be-tested liquid is dropped at the position where the electromagnetic field of the sensor is strongest using a micro syringe, the transmission spectrum (S 21 ) Obvious frequency splitting can be observed, realizing contact-type real-time sensing detection of the trace droplets to be measured. In order to avoid the rapid evaporation of the trace droplets, the data needs to be recorded quickly in the experiment; in order to ensure the accuracy and repeatability of the sensing detection experiment, the experiment was repeated many times.

[0038] In this embodiment, the micro-droplets to be tested use glucose solutions of different concentrations, and the volume of the micro-droplets is only 0.5 μL. In the experiment, deionized water and glucose solutions with concentrations of 18 mg / mL, 36 mg / mL, 90 mg / mL, 180 mg / mL, 270 mg / mL and 360 mg / mL are measured. Since the volume of the micro-droplets to be tested is 0.5 μL, it can be calculated that the measured glucose moles corresponding to the solutions with concentrations of 18 mg / mL, 36 mg / mL, 90 mg / mL, 180 mg / mL, 270 mg / mL and 360 mg / mL are 50 nmol, 100 nmol, 250 nmol, 500 nmol, 750 nmol and 1000 nmol, respectively. Figure 7 The experimental results of glucose trace droplet sensing detection using a trace biochemical sensor based on deep subwavelength singular point resonance, where (a) is the scatter mean, error bar and nonlinear fitting diagram of the resonance frequency splitting changing with glucose concentration, (b) is the scatter mean, error bar and nonlinear fitting diagram of the low-frequency resonance frequency changing with glucose concentration; therefore, the detection limit for the molar number of glucose in this embodiment is 50nmol.

[0039] It should be understood that the above embodiments and descriptions only describe the principles, main features and advantages of the present invention. Without departing from the spirit and scope of the present invention, the present invention may be subject to various changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.

Claims

1. A trace biochemical sensor based on deep subwavelength singular point resonance, characterized in that: It comprises an upper metal layer, an intermediate dielectric layer and a lower metal layer stacked in sequence from top to bottom, wherein the upper metal layer is a deep subwavelength singular point resonance structure pattern, the lower metal layer is an excitation microstrip line, and the resonance of the deep subwavelength singular point resonance structure pattern is excited by the excitation microstrip line.

2. A trace biochemical sensor based on deep subwavelength singular point resonance according to claim 1, characterized in that: The deep subwavelength singular point resonance structure pattern is specifically a resonance structure formed by coupling two identical deep subwavelength metal resonance units, and the deep subwavelength singular point resonance structure pattern supports two hybridized intrinsic resonance modes.

3. A trace biochemical sensor based on deep subwavelength singular point resonance according to claim 2, characterized in that: The singular point resonance in the deep subwavelength singular point resonance pattern is formed by coupling of two hybridized intrinsic resonance modes and is coupled and regulated by an excitation microstrip line.

4. A trace biochemical sensor based on deep subwavelength singular point resonance according to claim 2, characterized in that: The artificial localized surface plasmon resonance unit is specifically an Archimedean spiral metal wire.

5. The trace biochemical sensor based on deep subwavelength singular point resonance according to claim 3, characterized in that: The coupling regulation is achieved by exciting the relative rotation of the microstrip line and the deep subwavelength singular point resonant structure pattern.

6. A trace biochemical sensor based on deep subwavelength singular point resonance according to claim 2, characterized in that: The coupling points of the two deep subwavelength metal resonance units are located at the symmetric centers of the middle dielectric layer and the excitation microstrip line.

7. The trace biochemical sensor based on deep subwavelength singular point resonance according to claim 1, characterized in that: The intermediate dielectric layer is any one of FR4, F4B, RO4003, 3003, 4350, RT5880, 5870, 6002, 6006, 6010, 6035, 6202 produced by Rogers, N4000-13, N4000-13EPSI printed circuit and microwave circuit dielectric substrates produced by Nelco, or a semiconductor or dielectric of any one of Si, SiO2, Al2O3, GaAs, and GaN, or a flexible organic dielectric; the thickness of the intermediate dielectric layer is between 10nm and 10mm.

8. The trace biochemical sensor based on deep subwavelength singular point resonance according to claim 1, characterized in that: The material of the upper metal layer and the lower metal layer is any single material or any composite material of copper, tin, gold, silver, chromium, lead, platinum, zinc, aluminum, magnesium, and titanium; the thickness of the upper metal layer and the lower metal layer are both between 5nm and 1mm.

9. A trace biochemical sensing detection method, characterized in that: The steps include: Connecting two ends of the sensor of claim 1 to SMA connectors respectively, and connecting the two SMA connectors to a vector network analyzer via a coaxial cable; Using a microsyringe to drop a drop of the biochemical quantity to be measured on the sensor; Observe the transmission spectrum detected in the vector network analyzer. When frequency splitting is observed, it means that contact real-time sensing detection of the biochemical quantity droplet to be measured is achieved.

10. The trace biochemical sensing detection method according to claim 9, characterized in that: The biochemical quantity to be measured is specifically any one of a solution, an antigen, an antibody, an exosome, a bacterium, and a cell, and the trace biochemical sensing detection method adopts a contact or non-contact detection method according to actual needs.

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