A metamaterial microwave sensor integrating microfluidic technology for liquid sensing

Abstract

The application discloses a kind of integrated microfluidic technology applied to liquid sensing metamaterial microwave sensor, and relates to the technical field of metamaterial sensor.It includes: functional layer, dielectric layer, ground layer, microfluidic device;Functional layer, dielectric layer, ground layer are sequentially fixedly connected from top to bottom;Wherein, ground layer is grounded;Microfluidic device is fixedly connected with dielectric layer, and microfluidic device is resonant connection with functional layer.The application realizes to reach the coupling effect of enhancement to enhance sensitivity, and integrated microfluidic technology realizes the test to high-loss sample.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metamaterial sensor, more particularly, to a metamaterial microwave sensor integrating microfluidic technology for liquid sensing. BACKGROUND

[0002] With the development of modern technology, in the industrial, biomedical, pharmaceutical, agricultural, food, environmental and other fields, there is a need for precise measurement and real-time and non-destructive detection of materials. Microwave sensors have become the first choice for material measurement due to their advantages including high sensitivity, robustness, and low manufacturing and measurement cost. Microwave sensing operation is based on the reflection and transmission of open or closed resonant (or non-resonant) devices, and is one of the most popular devices for detecting material properties. Using microwave resonator-based dielectric measurement technology, changes in complex permittivity are reflected by measuring changes in reflection coefficient (S11), S21, fr, phase (φ) and quality factor (Q factor). Since microwave resonant technology is generally more sensitive to any changes in sample dielectric properties, they are more desirable compared to other microwave technologies based on non-resonant reflection and transmission measurements.

[0003] Among these many fields of material measurement, liquid material measurement accounts for a large proportion. For example, in biomedical medicine, the detection of blood glucose concentration, the proportioning of agricultural nutrient solution, pesticide composition, liquid culture medium composition, and the monitoring of drinking water, edible oil, gasoline and water quality in food and environment all require suitable sensors for detection. However, traditional microwave sensors are generally not suitable for measuring lossy liquid samples due to a significant reduction in overall quality factor, and because liquid measurement has high requirements for the integration and sensitivity of the sensing device, traditional microwave liquid sensors cannot meet the current needs of liquid measurement. In recent years, the emergence of metamaterials has largely solved these problems. Metamaterials are artificially engineered materials with electromagnetic properties such as negative permittivity and permeability, which are synthesized by embedding various geometric inclusions in the host medium. When the host medium interacts with electromagnetic waves, macroscopic metamaterial properties are produced. Because metamaterials exhibit strong electric and magnetic field localization, they can be combined with microwave sensors to improve sensitivity. Therefore, the microwave sensing platform based on metamaterials can meet the needs of high sensitivity and easy integration of sensors for liquid detection due to its improved compactness and high Q factor that is very sensitive to environmental changes.

[0004] Microfluidics, with its advantages of requiring fewer samples, small size, and ease of integration, can be integrated with metamaterial-based microwave sensing platforms to address the testing challenges of liquids with high loss characteristics on these platforms. Polydimethylsiloxane (PDMS), manufactured to appropriate dimensions, is suitable for biomedical applications due to its excellent properties in terms of biocompatibility, optical transparency, mechanical resistance, chemical inertness, and non-toxicity. To enhance the detection sensitivity of the liquid's complex permittivity, the channel is mounted in the most sensitive region of the ground plane, further amplifying the sensing sensitivity by passing through a highly concentrated SRR (open-ring resonator) sensing element. Simultaneously, the microfluidic PDMS channel is considered within the gap region of the SRR, where a very strong local electric field exists in the resonant frequency domain. Applying a liquid sample to this capacitive gap modifies the resonant frequency and quality factor, allowing the determination of the complex permittivity of the mixed liquid sample.

[0005] Traditional microwave sensors are generally unsuitable for measuring liquid samples with high loss and have low sensitivity. This invention utilizes the resonant properties of metamaterials to improve sensitivity and integrates microfluidic channels to address the significant reduction in the overall quality factor when measuring liquid samples with high loss.

[0006] Therefore, providing a microwave liquid sensor that integrates microfluidics technology and is based on metamaterial design to solve the problems of traditional microwave sensors being unsuitable for measuring lost liquid samples and having low sensitivity is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0007] In view of this, the present invention provides a metamaterial microwave sensor that integrates microfluidic technology for liquid sensing, in order to enhance the coupling effect and thus enhance the sensitivity, and to achieve the purpose of testing highly damaged samples by integrating microfluidic technology.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A metamaterial microwave sensor integrating microfluidic technology for liquid sensing, comprising:

[0010] Functional layer, dielectric layer, grounding layer, microfluidic device;

[0011] The functional layer, dielectric layer, and grounding layer are fixedly connected in sequence from top to bottom; among them, the grounding layer is grounded.

[0012] The microfluidic device is fixedly connected to the dielectric layer, and the microfluidic device is resonantly connected to the functional layer.

[0013] Optionally, the dielectric layer can be a polytetrafluoroethylene (PTFE) FBM high-frequency antenna board.

[0014] Optionally, the functional layer includes split microstrip lines;

[0015] Split microstrip lines are printed on a dielectric layer.

[0016] Optionally, the split microstrip line includes: a rectangular open loop, a first microstrip line, and a second microstrip line;

[0017] The rectangular open ring is composed of a rectangular open ring opening, a rectangular open ring opening segment, a rectangular open ring first wing segment, a rectangular open ring bottom segment, and a rectangular open ring second wing segment connected in sequence; wherein, the rectangular open ring is an integral structure;

[0018] The first microstrip line is fixedly connected to the first wing segment of the rectangular open ring, and the second microstrip line is fixedly connected to the second wing segment of the rectangular open ring.

[0019] Optionally, it may also include: a first waveguide port and a second waveguide port;

[0020] The first waveguide port is electrically connected to the first microstrip line, and the second waveguide port is electrically connected to the second microstrip line.

[0021] Optionally, the functional layer may also include a resonator;

[0022] The resonator is placed inside the rectangular open ring; wherein the resonator and the rectangular open ring are coupled by microwave.

[0023] Optionally, the resonator includes: an outer open-loop ring and an inner open-loop ring;

[0024] The outer open ring is located inside the inner open ring; the outer open ring, the inner open ring, and the rectangular open ring are coupled to each other.

[0025] Optionally, the microfluidic device is fixedly connected to the dielectric layer; wherein, the rectangular open ring and the resonator are both disposed between the microfluidic device and the dielectric layer.

[0026] Optionally, the microfluidic device includes an inlet channel, a microfluidic channel, and an outlet channel connected in sequence;

[0027] The bottom section of the open ring and the opening section of the outer open ring are resonantly connected to the microfluidic channel; the bottom section of the inner open ring, the opening section of the outer open ring, and the bottom section of the rectangular open ring are arranged sequentially from the inside to the outside and resonantly connected in sequence.

[0028] Optionally, a copper plate can be used as the grounding layer, and the copper plate can be grounded.

[0029] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a metamaterial microwave sensor that integrates microfluidic technology for liquid sensing, thereby achieving the following beneficial effects:

[0030] 1. This invention utilizes an improved microstrip line structure coupled with an open-loop resonator to enhance the sensitivity of the sensor, and integrates a microfluidic channel, enabling more accurate detection of the dielectric properties of high-loss liquids, requiring only a small sample volume.

[0031] 2. The overall structure of the present invention is further reduced in size, without a significant decrease in overall sensitivity, and the integration is higher. The structure of the present invention can be further reduced in size to achieve integration on different platforms.

[0032] 3. All metasurfaces in this invention can be manufactured using PCB technology, which is a mature and convenient process with low cost and good industrial applicability.

[0033] 4. This invention utilizes the special properties of metamaterials to enhance their coupling effect and thus improve sensitivity, and integrates microfluidic technology to achieve the testing of high-damage samples.

[0034] 5. This invention reduces sample consumption and allows for sample reuse, thereby reducing testing costs. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of a structure for applying integrated microfluidic technology to liquid sensing according to the present invention;

[0037] Figure 2 This is a top view of a metamaterial microwave sensor integrating microfluidic technology for liquid sensing according to the present invention.

[0038] Figure 3 This is a schematic diagram of the microfluidic channel structure of the present invention;

[0039] Figure 4 This is a schematic diagram of a specific embodiment of the present invention;

[0040] Figure 5 This is a simulation diagram of the transmission coefficient S21 obtained by electromagnetic simulation software CST when the microfluidic channel is not integrated in this invention;

[0041] Figure 6 The following are simulation diagrams of the sensing response obtained under different microfluidic channel conditions according to the present invention.

[0042] Figure 7This is a graph showing the change of the complex permittivity obtained by verifying the transport response of water-ethanol solutions with a water content of 0%-100% and a step size of 20% according to the present invention.

[0043] Figure 8 This is a graph showing the change of the complex permittivity obtained by verifying the transport response of water-ethanol solutions with a water content of 10%-90% and a step size of 20% according to the present invention.

[0044] Figure 9 This is a schematic diagram of the resonance frequency and peak attenuation of water-ethanol samples with water content (0%-100%) in 20% steps in the first group of experiments in a specific embodiment of the present invention.

[0045] Figure 10 This is a schematic diagram of the resonance frequency and peak attenuation of water-ethanol samples with water content (10%-100%) in 20% steps in the second group of experiments in a specific embodiment of the present invention.

[0046] In the diagram: 1-functional layer, 2-dielectric layer, 21-dielectric substrate surface, 23-first side of dielectric substrate, 24-second side of dielectric substrate, 3-ground layer, 4-split microstrip line, 41-rectangular open ring, 42-first microstrip line, 43-second microstrip line, 411-opening segment of rectangular open ring, 412-first wing segment of rectangular open ring, 413-bottom segment of rectangular open ring, 414-second wing segment of rectangular open ring, 4111-first segment of rectangular open ring, 4112-opening of rectangular open ring, 4113-second segment of rectangular open ring, 5-outer open ring, 6-inner open ring, 7-microfluidic device, 71-inlet channel, 72-microfluidic channel, 73-outlet channel, 8-first waveguide port, 9-second waveguide port, 10-clamp, 101-screw through hole, 11-SMA connector. Detailed Implementation

[0047] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0048] This invention discloses a metamaterial microwave sensor integrating microfluidic technology for liquid sensing, such as... Figure 1 As shown, it includes:

[0049] Functional layer 1, dielectric layer 2, grounding layer 3, microfluidic device 7;

[0050] Functional layer 1, dielectric layer 2, and grounding layer 3 are fixedly connected in sequence from top to bottom; among them, grounding layer 3 is grounded;

[0051] The microfluidic device 7 is fixedly connected to the dielectric layer 2, and the microfluidic device 7 is resonantly connected to the functional layer 1.

[0052] Furthermore, functional layer 1 is fixedly connected to the surface 21 of the dielectric substrate, and ground layer 3 is fixedly connected to the bottom surface of the dielectric substrate. The metamaterial microwave sensor is a two-port passive device excited by a plane wave. The overall size of the sensor is 20x16mm.

[0053] Furthermore, dielectric layer 2 is made of polytetrafluoroethylene F4BM high-frequency antenna board.

[0054] Furthermore, the dielectric layer 2 can be made of F4b material, where the dielectric constant of F4b material is 2.2 and the tangent loss is 0.001.

[0055] Furthermore, functional layer 1 includes split microstrip lines 4;

[0056] Split microstrip line 4 is printed on dielectric layer 2.

[0057] like Figure 2 As shown, the split microstrip line 4 further includes: a rectangular open loop 41, a first microstrip line 42, and a second microstrip line 43;

[0058] The rectangular open ring 41 is composed of a rectangular open ring opening 4112, a rectangular open ring opening segment 411, a rectangular open ring first wing segment 412, a rectangular open ring bottom segment 413, and a rectangular open ring second wing segment 414 connected in sequence; wherein, the rectangular open ring 41 is an integral structure.

[0059] The first microstrip line 42 is fixedly connected to the first wing segment 412 of the rectangular open ring, and the second microstrip line 43 is fixedly connected to the second wing segment 414 of the rectangular open ring.

[0060] Furthermore, the outer open ring 5, the inner open ring 6, and the rectangular open ring 41 are all open ring types. The open ring is composed of an open segment, a first wing segment, a bottom segment, and a second wing segment connected in sequence. The open segment is composed of a first sub-segment, an opening, and a second sub-segment arranged in sequence. The first wing segment is connected to the first sub-segment, the second wing segment is connected to the second sub-segment, and the opening is located at the center line of the open segment.

[0061] Furthermore, the rectangular open ring opening 4112 and the rectangular open ring opening segment 411 are composed of the first segment 4111, the rectangular open ring opening 4112, and the second segment 4113 of the rectangular open ring arranged sequentially; the first wing segment 412 of the rectangular open ring is connected to the first segment 4111 of the rectangular open ring, and the second wing segment 414 of the rectangular open ring is connected to the second segment 4113 of the rectangular open ring; the rectangular open ring opening 4112 is located at the center line of the rectangular open ring opening 4112 and the rectangular open ring opening segment 411.

[0062] Meanwhile, the split microstrip line 4 is composed of a microstrip line with a width of 1.5 mm and a rectangular open ring 41 with a side length of 8 x 7 mm; the opening size of the rectangular open ring 41 is 0.4 mm.

[0063] Furthermore, it also includes: the first waveguide port 8 and the second waveguide port 9;

[0064] The first waveguide port 8 is electrically connected to the first microstrip line 42, and the second waveguide port 9 is electrically connected to the second microstrip line 43.

[0065] Furthermore, such as Figure 3 As shown, the first waveguide port 8 is fixedly connected to the first side 23 of the dielectric substrate, and the second waveguide port 9 is fixedly connected to the second side 24 of the dielectric substrate; wherein, the first side 23 and the second side 24 of the dielectric substrate are two opposite sides of the dielectric substrate.

[0066] Furthermore, functional layer 1 also includes a resonator;

[0067] The resonator is disposed inside the rectangular open ring 41; wherein the resonator and the rectangular open ring 41 are coupled by microwave.

[0068] Furthermore, the resonator includes: an outer open-ended ring 5 and an inner open-ended ring 6;

[0069] The outer open ring 5 is disposed inside the inner open ring 6; wherein the outer open ring 5, the inner open ring 6, and the rectangular open ring 41 are coupled to each other.

[0070] Furthermore, the resonator employs a rectangular double-opening metal ring resonator, using a 0.035mm thick copper film with a conductivity of 5.8×10⁷ S / m. Both the outer open ring 5 and the inner open ring 6 are square open rings, with the outer ring 5 having a side length of 5.8mm and the inner ring 6 having a side length of 5mm. The width of both the outer and inner open rings is 0.2mm. The opening size of both the outer and inner rings is 0.4mm, and the minimum distance between the open-ring resonator and the microstrip line is 0.1mm. Both the resonator and the split microstrip line 4 are printed on the dielectric layer 2 using PCB technology.

[0071] Furthermore, the microfluidic device 7 is fixedly connected to the dielectric layer 2; wherein, the rectangular open ring 41 and the resonator are both disposed between the microfluidic device 7 and the dielectric layer 2.

[0072] Furthermore, the microfluidic device 7 is manufactured using polydimethylsiloxane (PDMS) at an appropriate size.

[0073] Furthermore, the overall size of the microfluidic device 7 is 8x7x2mm, with the flow channel measuring 7x1x0.1mm, which can load 0.7 microliters of sample to be tested.

[0074] Furthermore, the microfluidic device 7 includes an inlet channel 71, a microfluidic channel 72, and an outlet channel 73 connected in sequence;

[0075] The bottom section of the open ring and the opening section of the outer open ring 5 are resonantly connected to the microfluidic channel 72; the bottom section of the inner open ring 6, the opening section of the outer open ring 5, and the bottom section of the rectangular open ring 41 are arranged from the inside to the outside and resonantly connected in sequence.

[0076] Furthermore, the microfluidic channel 72 is integrated at the location where the electric field is most concentrated in the open-ring resonator.

[0077] Furthermore, grounding layer 3 is made of copper plate, and the copper plate is grounded.

[0078] Furthermore, the grounding layer 3 is made of copper film with a thickness of 0.035mm and a conductivity of 5.8×107S / m. The side length of the grounding layer 3 is equal to the side length of the dielectric layer 2, which is 20x16mm.

[0079] like Figure 4 As shown, it further includes a clamp 10, which consists of an upper clamp and a lower clamp. A functional layer 1, a dielectric layer 2, and a ground layer 3 are clamped between the upper clamp and the lower clamp. The clamp 10 is provided with a screw through hole 101 that extends from the upper clamp to the lower clamp. The upper clamp and the lower clamp are fixedly connected by screws in the screw through hole 101. The first waveguide port 8 and the second waveguide port 9 are both provided with SMA connectors 11.

[0080] Corresponding to the aforementioned sensor device, this invention also discloses a testing method for a metamaterial microwave sensor integrating microfluidic technology applied to liquid sensing, comprising:

[0081] The liquid to be tested is injected into the inlet channel 71 of the flow control device using a syringe or a more precise microsyringe, wherein the microfluidic device 7 is integrated into the sensor;

[0082] The liquid to be tested is injected through the inlet and stays at the microfluidic channel 72. The resonance intensity, i.e. the electric field intensity, of the double-open-ring resonator is the maximum at the microfluidic channel 72. The liquid to be tested being located in this region will greatly change the resonance effect of the resonator.

[0083] A vector network analyzer was used to connect the sensor's first waveguide port 8 and second waveguide port 9 to measure the S-parameters. By analyzing the changes in the S-parameters, it was found that different concentrations of liquid have different dielectric properties, and therefore different effects on the resonator.

[0084] By testing the S-parameters of liquids with different concentrations and then analyzing the data, the corresponding concentration of the solution can be determined.

[0085] The reason for connecting to the vector network analyzer for measurement is that, as a sensor chip, the integration method is determined by the user. This embodiment only tests and verifies the performance of the sensor chip.

[0086] In another specific embodiment, the present invention also discloses another testing method for metamaterial microwave sensors integrating microfluidic technology for liquid sensing, comprising:

[0087] like Figure 5 As shown, the sensor without integrated microfluidic device 7 was tested. The simulation frequency in CST Microwave Studio 2020 was set to 3-5 GHz. The resonant frequency of the sensor without integrated microfluidic device 7 was 4.156 GHz and the resonant depth was -29.83 dB.

[0088] like Figure 6 As shown, tests were conducted on sensors with no integrated microfluidic device 7, sensors with an integrated microfluidic device 7 having an empty microfluidic channel 72, sensors with an integrated microfluidic device 7 having a microfluidic channel 72 filled with 100% ethanol, and sensors with an integrated microfluidic device 7 having a microfluidic channel 72 filled with 100% water. When the microfluidic channel 72 was not integrated into the sensor, the resonant frequency and peak attenuation were at their maximum. By adding a PDMS channel, the resonant frequency shifted to the left and the peak attenuation decreased because part of the resonator was covered by PDMS.

[0089] like Figure 7 and Figure 8 As shown, a water-ethanol binary mixture was used to verify the sensor's performance. Two sets of experiments were conducted: the first set of experiments used a water-ethanol solution with a water content of 0%-100% in a step of 20%; the second set of experiments used a water-ethanol solution with a water content of 10%-90% in a step of 20%. In both the first and second sets of experiments, a water content of 50% was used as a reference. The changes in the complex permittivity of each set of data were studied by examining the resonant frequency shift and peak attenuation.

[0090] like Figure 9 , Figure 10 The diagram illustrates how the resonant frequency and peak attenuation change with the water content in the water-ethanol solution. It shows that the microwave sensor exhibits good linearity in both resonant frequency and peak attenuation with varying water content. The maximum resonant frequency shift is 286 MHz, and the maximum peak attenuation is -9.5 dB.

[0091] Based on the previous two sets of measurement results, a simple model was derived that uses the resonant frequency shift and peak attenuation change as functions of the complex permittivity. This simplified model can be defined as Equation (1):

[0092] Δε′=ε′-ε′ Ref ,Δε″=ε″-ε′ R ′ ef

[0093]

[0094] In the formula: f0 is the resonant frequency shift variable, |S 21 | represents the change in peak decay, m 11 m 12 m 21 m 22 For unknown coefficients, ε′ represents the real part of the dielectric constant of the liquid being measured, and ε″ represents the imaginary part of the dielectric constant of the liquid being measured. Ref ε" represents the real part of the dielectric constant of a 50% ethanol mixture. Ref This represents the imaginary part of the dielectric constant of a 50% concentration ethanol mixture.

[0095] Table 1 shows the measurement results of the first set of data, and Table 2 shows the complex permittivity values ​​of the water-ethanol solution at a resonant frequency of 3.56 GHz fitted by the Debye equation.

[0096] Table 1

[0097]

[0098] Table 2

[0099]

[0100]

[0101] Substituting the data from Tables 1 and 2 into Formula (1), we can obtain Formula (2). By inverting Formula (2), we can obtain Formula (3). Through Formula (3), we can determine the complex permittivity of the unknown liquid sample by measuring the resonance characteristics, thus realizing the measurement of liquid concentration.

[0102]

[0103]

[0104] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0105] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A metamaterial microwave sensor integrating microfluidic technology for liquid sensing, characterized in that, include: Functional layer (1), dielectric layer (2), grounding layer (3), microfluidic device (7); The functional layer (1), dielectric layer (2), and grounding layer (3) are fixedly connected from top to bottom; among them, the grounding layer (3) is grounded; The microfluidic device (7) is fixedly connected to the dielectric layer (2), and the microfluidic device (7) is resonantly connected to the functional layer (1); The functional layer (1) includes a split microstrip line (4); the split microstrip line (4) is printed on the dielectric layer (2) and includes: a rectangular open ring (41), a first microstrip line (42), and a second microstrip line (43); The rectangular open ring (41) is composed of a rectangular open ring opening (4112), a rectangular open ring opening segment (411), a rectangular open ring first wing segment (412), a rectangular open ring bottom segment (413), and a rectangular open ring second wing segment (414) connected in sequence; wherein, the rectangular open ring (41) is an integrated structure. The first microstrip line (42) is fixedly connected to the first wing section (412) of the rectangular open ring, and the second microstrip line (43) is fixedly connected to the second wing section (414) of the rectangular open ring; It also includes: a first waveguide port (8) and a second waveguide port (9); the first waveguide port (8) is electrically connected to the first microstrip line (42), and the second waveguide port (9) is electrically connected to the second microstrip line (43). The functional layer (1) also includes a resonator; The resonator is disposed inside the rectangular open ring (41); wherein the resonator is microwave coupled to the rectangular open ring (41), including: an outer open ring (5) and an inner open ring (6). The outer opening ring (5) is located outside the inner opening ring (6); wherein the outer opening ring (5), the inner opening ring (6), and the rectangular opening ring (41) are coupled to each other.

2. The metamaterial microwave sensor integrating microfluidic technology for liquid sensing according to claim 1, characterized in that, The dielectric layer (2) is made of polytetrafluoroethylene F4BM high-frequency antenna board.

3. The metamaterial microwave sensor integrating microfluidic technology for liquid sensing according to claim 1, characterized in that, The microfluidic device (7) is fixedly connected to the dielectric layer (2); wherein, the rectangular open ring (41) and the resonator are both disposed between the microfluidic device (7) and the dielectric layer (2).

4. A metamaterial microwave sensor integrating microfluidic technology for liquid sensing according to claim 3, characterized in that, The microfluidic device (7) includes an inlet channel (71), a microfluidic channel (72), and an outlet channel (73) connected in sequence. The bottom section of the open ring and the opening section of the outer open ring (5) are resonantly connected to the microfluidic channel (72); the bottom section of the inner open ring (6), the opening section of the outer open ring (5), and the bottom section of the rectangular open ring (41) are arranged from the inside to the outside in sequence and resonantly connected in sequence.

5. A metamaterial microwave sensor integrating microfluidic technology for liquid sensing according to claim 1, characterized in that, The grounding layer (3) is made of a metal copper plate, and the metal copper plate is grounded.

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