A non-contact biochemical sensor of artificial localized surface plasmons

Abstract

The application discloses a non-contact biochemical sensor of artificial local surface plasmon, which comprises an artificial surface plasmon transmission line, a dielectric substrate, an artificial local surface plasmon resonator array and a micro-flow cavity arranged on the artificial local surface plasmon resonator array and comprising a dielectric shell layer and a cavity pattern layer arranged in the dielectric shell layer, the cavity pattern layer is used for storing a solution to be measured, and the dielectric shell layer is in contact with the artificial local surface plasmon resonator array. The application provides a sensor in which the artificial local surface plasmon resonator array and the artificial surface plasmon transmission line are coupled with each other, the structures simulate optical surface plasmon characteristics in a microwave frequency band through a subwavelength periodic structure, electromagnetic field is strongly localized and slowly propagated, and therefore the interaction efficiency with a sample is enhanced, the characteristics prolong the interaction time of a measured sample and electromagnetic waves, and higher sensitivity and a Q factor are provided.

Description

Technical Field

[0001] This invention relates to the field of radio frequency sensor technology, and in particular to a non-contact biochemical sensor based on artificial localized surface plasmons. Background Technology

[0002] A sensor is a device, module, or system that responds to specific parameters in the environment and converts changes in those parameters into electrical signals for subsequent information transmission and processing. Sensor technology, along with computer technology and communication technology, is considered one of the three pillars of information technology.

[0003] Microwave sensors, as a novel type of sensor, operate on the principle that when the content or concentration of a analyte changes, its dielectric constant changes, resulting in corresponding changes in the absorbed or reflected microwaves. Quantifying these microwave changes allows for the determination of the analyte's content or concentration. Microwave sensors offer advantages such as non-contact operation, continuous response, convenience, and ease of integration into devices, making them widely used in biomedical monitoring (e.g., blood glucose and blood oxygen detection), environmental monitoring (e.g., water pollutant analysis), and the food industry (e.g., component analysis).

[0004] Currently, most microwave sensors used for biochemical sensing are based on various patch antennas. By designing different shapes of these devices, their equivalent capacitance and equivalent inductance can be changed, thereby altering their microwave characteristics. However, water molecules in aquatic biochemical samples exhibit strong absorption of microwave energy, leading to challenges such as decreased sensitivity and reduced Q-factor for traditional microwave sensors during detection. Summary of the Invention

[0005] In view of the above problems, this invention provides a non-contact biochemical sensor based on artificial localized surface plasmon resonances (ALPs) to address the issues of low sensitivity and low Q-factor in traditional microwave sensors. This invention proposes a sensor that couples an ALP resonator array with an ALP plasmon transmission line. These structures, through subwavelength periodic structures, simulate the characteristics of optical surface plasmons in the microwave band, achieving strong localization of the electromagnetic field and slow wave propagation, thereby enhancing the interaction efficiency with the sample. This characteristic prolongs the interaction time between the sample and the electromagnetic wave, providing higher sensitivity and a higher Q-factor.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a non-contact biochemical sensor based on artificial localized surface plasmons, comprising:

[0008] An artificial surface plasmon polariton transmission line has an overall symmetrical double-sided structure, including a coplanar waveguide, multiple complementary open-loop resonators, and a gradient corrugated strip connecting the coplanar waveguide and the multiple complementary open-loop resonators.

[0009] A dielectric substrate is disposed on the artificial surface plasmon transport line;

[0010] An artificial localized surface plasmon resonator array is disposed on the dielectric substrate, comprising two symmetrically arranged artificial localized surface plasmon resonators and a central disk disposed within the artificial localized surface plasmon resonators; the artificial localized surface plasmon resonator array is coupled to the very center of the artificial surface plasmon transmission line.

[0011] A microfluidic cavity, disposed on the artificial localized surface plasmon resonator array, includes a dielectric shell layer and a cavity pattern layer disposed within the dielectric shell layer. The cavity pattern layer is used to store the test solution. The dielectric shell layer is in contact with the artificial localized surface plasmon resonator array. The microfluidic cavity is used to separate the test solution from the artificial localized surface plasmon resonator array to achieve non-contact biochemical sensing.

[0012] In one embodiment of the present invention, the artificial localized surface plasmon resonator array and the microfluidic cavity are bonded together by nano-double-sided adhesive.

[0013] In one embodiment of the present invention, the complementary open-ring resonator is a ring resonator with four openings.

[0014] In one embodiment of the present invention, the artificial localized surface plasmon resonator array and the artificial surface plasmon transport line are made of a single material or a composite material of copper, tin, gold, silver, chromium, lead, platinum, zinc, aluminum, magnesium or titanium.

[0015] In one embodiment of the present invention, the microfluidic cavity is made of polydimethylsiloxane or SiO2.

[0016] In one embodiment of the present invention, the non-contact biochemical sensor is provided with two ports, which can be connected to a vector network analyzer via an SMA adapter.

[0017] In one embodiment of the invention, a single artificial localized surface plasmon resonator is constructed by etching 60 grooves into a metal ring. The inner and outer radii of the metal ring are 2.52 mm and 9 mm, respectively. The length and width of the grooves are 6.12 mm and 0.24 mm, respectively. The angle between adjacent grooves is 6°. Another artificial localized surface plasmon resonator is designed symmetrically according to the x=0 plane.

[0018] In one embodiment of the present invention, the center band length, width, and gap width of the coplanar waveguide are 6 mm, 4 mm, and 0.2 mm, respectively, and the rectangular width and the radius of the arc-shaped ground plane of the coplanar waveguide are 6 mm and 17.3 mm, respectively.

[0019] In one embodiment of the present invention, the gradient corrugated strip has five gradients, the heights of which are 1mm, 2mm, 3mm, 4mm, 5mm and 6mm respectively.

[0020] In one embodiment of the present invention, the metal ring and the middle gap of the complementary open-loop resonator have widths of 0.35 mm and 0.25 mm, respectively, the width of the open-loop is 0.25 mm, the width and height of the periodic structure are 5 mm and 6 mm, respectively, and the width and height of the bottom transmission band are 6 mm and 2 mm, respectively.

[0021] The beneficial effects achieved by this invention are as follows:

[0022] The present invention provides a non-contact biochemical sensor based on artificial localized surface plasmons, which has the following advantages:

[0023] 1. By coupling the artificial localized surface plasmon array resonator array and the artificial surface plasmon transmission line, the electromagnetic field is strongly localized and the slow wave propagation is achieved, resulting in higher sensitivity and Q factor.

[0024] 2. The periodic element structure of the artificial surface plasmon polariton transport line is designed as a complementary open-loop resonator with four openings, which has a stronger field confinement capability and makes the interaction time between the sample under test and the electromagnetic wave longer.

[0025] 3. Designing an artificial localized surface plasmon resonator composed of two completely symmetrical SLSP resonators can enhance electric field coupling, expand the sensing area, introduce multimode resonance modes, and improve detection stability.

[0026] 4. By utilizing the large evanescent field extension space of low-frequency artificial surface plasmons and microfluidic cavities with dielectric shell layers, non-contact biochemical sensing can be achieved.

[0027] Therefore, this non-contact biochemical sensor has advantages such as low frequency band, passive circuitry, high sensitivity, convenient detection, and high environmental robustness. Furthermore, the non-contact nature of the biochemical sensor avoids contamination of the sensor chip, making it significant for practical applications. The structure of this non-contact biochemical sensor simulates the characteristics of optical surface plasmons in the microwave band through a subwavelength periodic structure, achieving strong localization of the electromagnetic field and slow wave propagation, thereby enhancing the interaction efficiency with the sample. This characteristic prolongs the interaction time between the sample and the electromagnetic wave, providing higher sensitivity and a higher Q factor. Attached Figure Description

[0028] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0029] Figure 1 A perspective view of the non-contact biochemical sensor provided by the present invention;

[0030] Figure 2 A schematic diagram of the structure of the artificial localized surface plasmon resonator array provided by the present invention;

[0031] Figure 3 This is a rear view of the non-contact biochemical sensor provided by the present invention.

[0032] Figure 4 This is a schematic diagram of the complementary open-loop resonator provided by the present invention;

[0033] Figure 5 This is a cross-sectional view of the non-contact biochemical sensor provided by the present invention.

[0034] In the figure: 1. Artificial localized surface plasmon resonator; 2. Central disk; 3. Coplanar waveguide; 4. Gradient corrugated strip; 5. Complementary open-loop resonator; 6. Dielectric substrate; 7. Dielectric shell layer; 8. Cavity pattern layer. Detailed Implementation

[0035] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. These embodiments are merely illustrative of the technical solution of the present invention and are therefore intended to limit the scope of protection of the present invention.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0037] In the description of the embodiments of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "multiple" means two or more, unless otherwise explicitly defined.

[0038] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least some embodiments of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0039] In the description of the embodiments of this invention, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0040] Example 1

[0041] like Figures 1 to 5 As shown, this embodiment provides a non-contact biochemical sensor based on artificial localized surface plasmons, comprising:

[0042] Artificial surface plasmon resonance transmission line, wherein the artificial surface plasmon resonance transmission line has an overall symmetrical double-sided structure, including a coplanar waveguide 3, a plurality of complementary open-loop resonators 5, and a gradient corrugated strip 4 connecting the coplanar waveguide 3 and the plurality of complementary open-loop resonators 5;

[0043] Dielectric substrate 6 is disposed on the artificial surface plasmon transmission line;

[0044] An artificial localized surface plasmon resonator array is disposed on the dielectric substrate 6, including two completely symmetrically arranged artificial localized surface plasmon resonators 1, and a central disk 2 disposed within the artificial localized surface plasmon resonators 1; the artificial localized surface plasmon resonator array is coupled to the very center of the artificial surface plasmon transmission line.

[0045] A microfluidic cavity, disposed on the artificial localized surface plasmon resonator array, includes a dielectric shell layer 7 and a cavity pattern layer 8 disposed within the dielectric shell layer 7. The cavity pattern layer 8 is used to store the test solution. The dielectric shell layer 7 is in contact with the artificial localized surface plasmon resonator array. The microfluidic cavity is used to separate the test solution from the artificial localized surface plasmon resonator array to achieve non-contact biochemical sensing.

[0046] Optionally, the artificial localized surface plasmon resonator array and the microfluidic cavity are bonded together using nano-double-sided adhesive. The microfluidic cavity consists of a dielectric shell layer 7 and a cavity pattern layer 8, used to isolate the test solution from the sensor during testing to achieve non-contact biochemical sensing while ensuring that the test solution is within the optimal sensing area. The sensing signal originates from the resonant frequency of the artificial localized surface plasmon resonator array; changes in the surrounding equivalent dielectric constant cause changes in the resonant frequency. The change in the surrounding equivalent dielectric constant signal originates from the change in the content or concentration of the biochemical sample to be detected within the microfluidic cavity. Ideally, the overlap between the microfluidic cavity area and the artificial localized surface plasmon resonator array area should be as large as possible.

[0047] Optionally, the complementary open-ring resonator 5 is a ring resonator with four openings.

[0048] Optionally, the artificial localized surface plasmon resonator array and the artificial surface plasmon transport line are made of a single material or a composite material of copper, tin, gold, silver, chromium, lead, platinum, zinc, aluminum, magnesium, or titanium.

[0049] Optionally, the microfluidic cavity is made of polydimethylsiloxane or SiO2.

[0050] Optionally, the non-contact biochemical sensor has two ports, which can be connected to a vector network analyzer via an SMA adapter.

[0051] The non-contact biochemical sensor is placed in a test environment, and the test solution is injected into the microfluidic cavity with the same injection speed and injection time using an injection pump. The concentration of the test solution is increased at a fixed gradient, and the S-parameters of the vector network analyzer are recorded. By analyzing the sensitivity and linearity of these S-parameters, the biochemical sensing requirements can be met.

[0052] The geometric parameters involved in this invention are typically selected and optimized based on simulation results.

[0053] In summary, the non-contact biochemical sensor based on artificial localized surface plasmons provided by this invention has the following advantages:

[0054] 1. By coupling the artificial localized surface plasmon array resonator array and the artificial surface plasmon transmission line, the electromagnetic field is strongly localized and the slow wave propagation is achieved, resulting in higher sensitivity and Q factor.

[0055] 2. The periodic element structure of the artificial surface plasmon polariton transport line is designed as a complementary open-loop resonator with four openings, which has a stronger field confinement capability and makes the interaction time between the sample under test and the electromagnetic wave longer.

[0056] 3. Designing an artificial localized surface plasmon resonator composed of two completely symmetrical SLSP resonators can enhance electric field coupling, expand the sensing area, introduce multimode resonance modes, and improve detection stability.

[0057] 4. By utilizing the large evanescent field extension space of low-frequency artificial surface plasmons and microfluidic cavities with dielectric shell layers, non-contact biochemical sensing can be achieved.

[0058] Therefore, this non-contact biochemical sensor has advantages such as low frequency band, passive circuitry, high sensitivity, convenient detection, and high environmental robustness. Furthermore, the non-contact nature of the biochemical sensor avoids contamination of the sensor chip, making it significant for practical applications. The structure of this non-contact biochemical sensor simulates the characteristics of optical surface plasmons in the microwave band through a subwavelength periodic structure, achieving strong localization of the electromagnetic field and slow wave propagation, thereby enhancing the interaction efficiency with the sample. This characteristic prolongs the interaction time between the sample and the electromagnetic wave, providing higher sensitivity and a higher Q factor.

[0059] Example 2

[0060] The artificial localized surface plasmon resonator array in this embodiment is as follows: Figure 2 As shown, the geometric parameters are as follows: a 0.44mm thick Teflon dielectric substrate with a width and length of 39mm and 158mm respectively; a central disk made of metal with a radius of 2.16mm; a single artificial localized surface plasmon resonator constructed by etching 60 grooves in a metal ring with an inner and outer radius of 2.52mm and 9mm respectively; a groove with a length and width of 6.12mm and 0.24mm respectively; and an angle of 6° between adjacent grooves. Another artificial localized surface plasmon resonator is designed symmetrically according to the x=0 plane.

[0061] The microfluidic cavity structure in this embodiment is as follows: Figure 2 As shown, polydimethylsiloxane material is used. The length, width, and height of the outer shell layer are 36 mm, 19.2 mm, and 3.6 mm, respectively. The length, width, and height of the cavity pattern layer are 27 mm, 14.4 mm, and 0.36 mm, respectively. The volume of the liquid-filled cavity is 140 μL, and it is also symmetrical about the x=0 plane.

[0062] The artificial surface plasmon resonance transport line in this embodiment is as follows: Figure 3 As shown, the geometric parameters are: the center band length, width, and gap width of the coplanar waveguide are 6mm, 4mm, and 0.2mm, respectively; the rectangle width and the radius of the arc-shaped ground plane of the coplanar waveguide are 6mm and 17.3mm, respectively; the gradient corrugated strip has five gradients with heights of 1mm, 2mm, 3mm, 4mm, 5mm, and 6mm, respectively; a single complementary open-loop resonator is shown... Figure 4 As shown, the widths of the metal ring and the intermediate gap are 0.35mm and 0.25mm, respectively; the width of the open ring is 0.25mm; the width and height of the periodic structure are 5mm and 6mm, respectively; and the width and height of the bottom conveyor belt are 6mm and 2mm, respectively.

[0063] In this embodiment, the metals used for the artificial localized surface plasmon resonator array and the artificial surface plasmon transport line are both copper and are fabricated using an etching process; the microfluidic cavity structure is fabricated using a polydimethylsiloxane molding process.

[0064] Non-contact biochemical sensor testing environment: The microfluidic cavity was bonded to the artificial localized surface plasmon resonator array using nano-double-sided adhesive. Two 50Ω SMA (Sub-Miniature A) adapters were then connected to the two ports of the sensor. The soldered sensor was fixed on the test stage. The SMA adapters were connected to a Vector Network Analyzer (VNA) to test the sensor's S-parameters. Two small holes were provided in the dielectric shell layer of the microfluidic cavity for inserting capillaries for liquid inflow and outflow within the cavity's patterned layer 8.

[0065] During the measurement process, the biochemical solution to be tested, with an equal concentration gradient, was injected into the microfluidic cavity sequentially using a syringe pump at the same injection rate and time. After each experiment, the microfluidic cavity was rinsed with plasma water before the next experiment. After each injection of the biochemical solution, the sample was allowed to stand for 1 minute to allow the resonance peak to stabilize before the sensing test was performed. The shift trend of the resonant frequency of the microwave resonator was observed. The VNA was connected to the computer via USB to read the sensor's S-parameters in real time. Finally, the recorded S-parameters were analyzed to derive the sensor's sensitivity, linearity, Q-factor, and other parameters.

[0066] Although the invention has been described with reference to preferred embodiments, various modifications can be made and components can be replaced with equivalents without departing from the scope of the invention. In particular, the technical features mentioned in the various embodiments can be combined in any manner as long as there is no structural conflict. The invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A non-contact biochemical sensor using artificial localized surface plasmons, characterized in that, include: Artificial surface plasmon polariton transmission line, wherein the artificial surface plasmon polariton transmission line has a symmetrical double-sided structure, including a coplanar waveguide (3), a plurality of complementary open-ring resonators (5), and a gradient corrugated strip (4) connecting the coplanar waveguide (3) and the plurality of complementary open-ring resonators (5). The dielectric substrate (6) is disposed on the artificial surface plasmon transmission line; An artificial localized surface plasmon resonator array is disposed on the dielectric substrate (6), including two completely symmetrically arranged artificial localized surface plasmon resonators (1) and a central disk (2) disposed within the artificial localized surface plasmon resonators (1); the artificial localized surface plasmon resonator array is coupled to the very center of the artificial surface plasmon transmission line. The microfluidic cavity, disposed on the artificial localized surface plasmon resonator array, includes a dielectric shell layer (7) and a cavity pattern layer (8) disposed within the dielectric shell layer (7). The cavity pattern layer (8) is used to store the solution to be tested. The dielectric shell layer (7) is in contact with the artificial localized surface plasmon resonator array. The microfluidic cavity is used to isolate the solution to be tested from the artificial localized surface plasmon resonator array to achieve non-contact biochemical sensing. The artificial localized surface plasmon resonator array is bonded to the microfluidic cavity using nano-double-sided adhesive. The complementary open-loop resonator (5) is a ring resonator with four openings. A single artificial localized surface plasmon resonator (1) is constructed by etching 60 grooves in a metal ring. The inner and outer radii of the metal ring are 2.52 mm and 9 mm, respectively. The length and width of the grooves are 6.12 mm and 0.24 mm, respectively. The angle between adjacent grooves is 6°. Another artificial localized surface plasmon resonator (1) is designed symmetrically according to the x=0 plane. The complementary open-ring resonator (5) has metal ring and intermediate gap widths of 0.35mm and 0.25mm, respectively, open ring width of 0.25mm, periodic structure width and height of 5mm and 6mm, respectively, and bottom transmission strip width and height of 6mm and 2mm, respectively.

2. The non-contact biochemical sensor of artificial localized surface plasmons according to claim 1, characterized in that, The artificial localized surface plasmon resonator array and the artificial surface plasmon transport line are made of a single material or a composite material of copper, tin, gold, silver, chromium, lead, platinum, zinc, aluminum, magnesium, or titanium.

3. The non-contact biochemical sensor of artificial localized surface plasmons according to claim 1, characterized in that, The microfluidic cavity is made of polydimethylsiloxane or SiO2.

4. The non-contact biochemical sensor of artificial localized surface plasmons according to claim 1, characterized in that, The non-contact biochemical sensor has two ports, which can be connected to a vector network analyzer via an SMA adapter.

5. A non-contact biochemical sensor based on artificial localized surface plasmons according to claim 1, characterized in that, The center band length, width and gap width of the coplanar waveguide (3) are 6mm, 4mm and 0.2mm respectively, and the rectangular width and arc ground plane radius of the coplanar waveguide (3) are 6mm and 17.3mm respectively.

6. A non-contact biochemical sensor based on artificial localized surface plasmons according to claim 1, characterized in that, The gradient corrugated strip (4) has six gradients, with heights of 1mm, 2mm, 3mm, 4mm, 5mm and 6mm respectively.

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