Multi-port broadband destructive sensor based on composite left-right-handed transmission line

Abstract

The present invention discloses a multi-port broadband destructive sensor based on a composite left-handed transmission line, comprising a first annular coupler, a second annular coupler and two connecting lines; the two ends of the two connecting lines are respectively connected to the two signal output ports of the first annular coupler and the signal input port of the second annular coupler, and the other three ports of the first and second annular couplers can be set as ports of the sensor or end-loaded with matching loads according to requirements, so that the sensor can be freely tuned between two ports, three ports, four ports and five ports; composite left-handed branches are respectively loaded in the two connecting lines, used as test areas, and a microfluidic channel is provided in the test area, and the microfluidic channel is provided with an inlet and an outlet for liquid samples. The present invention has high sensitivity, wide frequency band, simple detection method, and is easy to integrate, and has the potential to be combined with other devices into a micro-analysis system.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave measurement, and in particular relates to a multi-port broadband destructive sensor based on composite left-handed and right-handed transmission lines. Background Art

[0002] As the volume of the object being measured decreases, the sensitivity of the sensor becomes one of the key design parameters. For example, when detecting components such as cell suspensions, particle recombinant media, and DNA large biological molecule recombinants, traditional test schemes cannot identify small changes in these components due to their sensitivity. An effective solution is to use a destructive sensor, which uses signal interference destructive technology to effectively eliminate the background noise of the transmission line and achieve strong testing under weak background signals. This technology has been favored by many researchers internationally and has achieved the testing of dielectric properties of tiny samples such as cells. In recent years, more and more researchers have continuously proposed broadband testing schemes based on the initial point frequency testing scheme. The broadband test scheme has been reported in the literature "Y.Cui and P.Wang, The design and operation of ultra-sensitive and tunable radio-frequency interferometers[J], IEEE Transactions on MicrowaveTheory and Techniques, 2014, 62(12):3172–3182.", "Kozhevnikov, Alexay, Widebandradio-frequency device for measurements of dielectric properties of small volumes of liquids[J]. Measurement Science and Technology, 2010, 21(4):043001.", and "Saghati AP, Batra JS, Kameoka J, et al. A Metamaterial-Inspired WidebandMicrowave Interferometry Sensor for Dielectric Spectroscopy of LiquidChemicals[J]. IEEE Transactions on Microwave Theory and These documents all use non-integrated modules to implement broadband test solutions. Although they have achieved good results, it is difficult to achieve an easily integrated broadband miniaturized solution. Moreover, most of these solutions are dual-port tests. Multi-frequency, broadband, and miniaturization technologies have always been the eternal research topics in the field of microwave testing. Therefore, providing a highly sensitive broadband and multi-frequency detection solution is one of the important means to explore the interaction mechanism between microwaves and media.

[0003] In recent years, the continuous development of microwave technology, especially the rapid development of composite left-handed and right-handed transmission lines, has provided new opportunities for new breakthroughs in various information components and has attracted widespread attention in all walks of life. The characteristics of electromagnetic metamaterials such as subwavelength resonance, negative refraction, perfect lens, energy convergence and surface wave suppression make them popular among scientific researchers in the field of microwave testing. In the field of microwave testing, the introduction of composite left-handed and right-handed transmission lines can also broaden the test bandwidth of microwave devices, reduce device size and improve test sensitivity.

[0004] In view of this, the present invention proposes a new type of destructive sensor, which is a bandwidth-enhanced annular coupler based on a hybrid left-handed transmission line structure, and belongs to a multi-port test device with tunable ports. The test device can be set to dual-port, three-port, four-port and five-port as needed. Due to the introduction of composite left-handed transmission lines in the design process, the broadband multi-port microwave sensor can be symmetrical, thereby reducing the size of the device, so that the device has the advantages of low profile, miniaturization, easy processing, low price and easy integration. In addition, we loaded composite left-handed branches in the test area of ​​the sensor to enhance the electric field in the test area and further improve the test sensitivity. Summary of the invention

[0005] In view of the problems of narrow bandwidth and large size in existing destructive sensors, the purpose of the present invention is to provide a multi-port broadband destructive sensor based on composite left-handed and right-handed transmission lines, which can sensitively sense the dielectric properties of microfluids and their tiny changes.

[0006] The present invention is implemented according to the following technical solutions:

[0007] A multi-port broadband destructive sensor based on composite left-handed and right-handed transmission lines comprises a first annular coupler, a second annular coupler and two connecting lines; the first annular coupler and the second annular coupler each comprise a signal input port, two signal output ports and a signal isolation port; the two signal output ports of the first annular coupler have opposite phases, and the two signal output ports of the second annular coupler have the same phase; the two ends of the two connecting lines are respectively connected to the two signal output ports of the first annular coupler and the signal input port of the second annular coupler, and the other three ports of the first and second annular couplers can be set as sensor ports or end-loaded with matching loads according to requirements, so that the sensor can be freely tuned between two ports, three ports, four ports and five ports; composite left-handed and right-handed branches are respectively loaded in the two connecting lines to serve as test areas, a microfluidic channel is provided in the test area, and the microfluidic channel is provided with an inlet and an outlet for liquid samples.

[0008] Preferred solution: The first annular coupler includes a signal input port I, a signal output port I, a signal isolation port I and a signal output port II, all of which are microstrip transmission lines; one end of the signal input port I, the signal output port I, the signal isolation port I and the signal output port II are connected to form a circular transmission line with a notch; wherein the notch between the signal input port I and the signal output port I is loaded with a composite left-handed transmission line composed of SMT patches, which is used to achieve a phase at the signal output port I that leads the signal input port I by 90 degrees, and a phase at the signal output port II that lags the signal input port I by 90 degrees, so that the phase difference between the signal output port I and the signal output port II is 180 degrees.

[0009] Preferred solution: The second annular coupler includes a signal input port II, a signal output port III, a signal isolation port II and a signal output port IV, all of which are microstrip transmission lines; one end of the signal input port II, the signal output port III, the signal isolation port II and the signal output port IV are connected to form a circular transmission line with a notch; wherein the notch between the signal output port III and the signal output port IV is loaded with a composite left-handed transmission line composed of SMT patches, which is used to achieve that the signal of the signal output port IV leads the signal output port III by 90 degrees, and the signal from the signal isolation port II lags behind by 90 degrees in phase.

[0010] Preferred solution: The second annular coupler includes a signal input port III, a signal output port V, a signal isolation port III and a signal output port VI, all of which are microstrip transmission lines; one end of the signal input port III, the signal output port V, the signal isolation port III and the signal output port VI are connected to form a circular transmission line; wherein three ports are -90 degree transmission lines, and the remaining one port is a -270 degree transmission line.

[0011] Preferred solution: the composite left-hand and right-hand branches are composed of a series interdigitated capacitor and a parallel branch line inductor of a microstrip structure.

[0012] A preferred solution: The series interdigitated capacitor includes eight microstrip branches with right-angle turns, wherein the first and eighth microstrip branches with right-angle turns have their two ends connected to connecting lines respectively, and the other end is connected to one end of the second or seventh microstrip branch with right-angle turns, and the remaining microstrip branches with right-angle turns are connected end to end.

[0013] Preferred solution: The parallel branch line inductor is constructed of a zigzag inductor, which is composed of eight right-angled slits etched on a metal layer, wherein one end of the first right-angled slit is connected to the second right-angled slit, the end of the last right-angled slit is open, and the remaining right-angled slits are connected end to end.

[0014] Preferred solution: During the test, the input port and output port of the sensor are respectively connected to the vector network analyzer, and the object to be tested is injected into the inlet of the microfluidic channel by a propeller, and the sample is pushed out from the outlet at a predetermined interval, and then the microfluidic channel is cleaned with deionized water, and another sample is tested after drying.

[0015] Preferred solution: the microfluidic channel comprises a PDMS layer with a thickness of 3 mm, a width of 2.5 mm and a length of 3.0 mm; the inlet and outlet of the microfluidic channel are connected to the PDMS by low-loss polytetrafluoroethylene tubes.

[0016] Beneficial effects of the present invention:

[0017] The multi-port broadband destructive sensor based on composite left-handed and right-handed transmission lines provided by the present invention has many novel advantages when used for detecting the dielectric properties of microfluids and their slight changes: the invention belongs to an integrated, miniaturized, broadband and multi-port structure; the structure proposed by the present invention can include two or three signal destructive ports, while the existing microwave interferometer generally includes one signal destructive port, and multiple signal destructive ports can obtain more information about the object to be measured, so that the extraction of the dielectric properties of the object to be measured is more accurate; by loading series interdigitated capacitors and parallel branch line inductance branches in the test area, the volume of the fluid to be measured can be greatly reduced, and the technology can be effectively applied to the fields of cytology, electromagnetic field biomedicine, microwave chemical non-thermal effects and protein thermal denaturation; and the device has high sensitivity, wide bandwidth, simple detection method, easy integration, and has the potential to be combined with other devices into a micro-analysis system. The device proposed by the present invention is a dual-port measurement, which can avoid the problem of multiple solutions, so the information capture results of slight changes in the dielectric properties of the fluid are more accurate and more reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an improper limitation of the present invention. Obviously, the accompanying drawings described below are only some embodiments. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0019] In the attached picture:

[0020] Figure 1 A preferred embodiment of the multi-port broadband destructive sensor of the present invention;

[0021] Figure 2 Another preferred embodiment of the multi-port broadband destructive sensor of the present invention;

[0022] Figure 3 is the transmission parameter of the present invention before loading the microfluid;

[0023] Figure 4 is the transmission parameter S when only a certain high-loss sample is loaded in the test area of ​​the present invention. 21 Schematic diagram;

[0024] Figure 5 is the transmission parameter S when only a certain high-loss sample is loaded in the test area of ​​the present invention. 31 Schematic diagram.

[0025] Figure symbols: 1-ground plane, 2-dielectric layer, 3-signal input port I, 4-signal output port I, 41-signal output port II, 5-composite left-handed and right-handed transmission line, 6-signal isolation port I, 7-connecting line, 8-parallel branch line inductor, 9-series interdigital capacitor, 10-signal input port II, Path, 12-signal output port III, 13-signal isolation port II, 14-signal output port IV, 15-signal input port III, 16-signal output port V, 17-signal isolation port III, 18-signal output port VI.

[0026] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but are intended to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0028] In the description of the present invention, it should be noted that the directions or positional relationships indicated by terms such as “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “inside” and “outside” are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0029] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0030] like Figure 1 , Figure 2 As shown, a multi-port broadband destructive sensor based on a composite left-handed transmission line includes a ground plane 1, a dielectric layer 2, and a first annular coupler, a second annular coupler and two connecting lines 7 are arranged on the dielectric layer 2; the first annular coupler and the second annular coupler each include a signal input port, two signal output ports and a signal isolation port, and the characteristic impedance of all ports is 50 ohms; the two signal output ports of the first annular coupler have opposite phases, and the two signal output ports of the second annular coupler have the same phase; the two ends of the two connecting lines 7 are respectively connected to the two signal output ports of the first annular coupler and the signal input port of the second annular coupler, and the other three ports of the first and second annular couplers can be set as sensor ports or end-loaded with matching loads according to requirements, so that the sensor can be freely tuned between two ports, three ports, four ports and five ports; the total length of the first annular coupler and the second annular coupler is The length between each port is Composite left-handed and right-handed branches are loaded in the two connecting lines 7 respectively, which are used as test areas. Microfluidic channels are arranged in the test areas, and the microfluidic channels are provided with inlets and outlets for liquid samples. Therefore, this scheme realizes broadband high-sensitivity detection from two technical levels. On the one hand, interference destructive phase is used to eliminate the background noise of the transmission line. On the other hand, composite left-handed and right-handed transmission lines are loaded in the test area to enhance their electric field and enhance the interaction between microwaves and the object under test.

[0031] The traditional second annular coupler is composed of three right-handed transmission lines with a phase shift of -90 degrees and one right-handed transmission line with a phase shift of -270 degrees. The second annular coupler used in the present invention replaces the -270-degree right-handed transmission line of the traditional annular coupler with a 90-degree composite left-right-handed transmission line. The replacement does not change the phase difference between the output ports. The only difference is that the bandwidth of the traditional annular coupler is changed. In particular, the composite left-right-handed transmission line is implemented by an SMT patch.

[0032] Through this design scheme, the relevant parameters are optimized, and the proposed sensor can be tested at 1GHz-4GHz. When the sample to be tested is placed on the test area, the transmission coefficient and the destructive frequency band of the sensor will be offset. The changes in the transmission coefficient amplitude and the destructive frequency reflect the changes in the loss tangent and the real part of the dielectric properties of the object to be tested. The present invention utilizes the above-mentioned transmission principle of microwaves to design a bandwidth-enhanced microwave interferometer. The designed circuit and microfluidic channel in the test area enable the object to fully affect the transmission of electromagnetic waves, so the detection sensitivity of the device can be greatly improved. The detection device was numerically simulated by the finite element algorithm. The experimental results show that the device can achieve signal cancellation in the frequency band of 1GHz-4GHz. The composite left-handed and right-handed transmission line branches loaded in the test area can enable the microwave interferometer to sensitively perceive the weak information caused by nanoliter-level microfluids in a broadband.

[0033] like Figure 1 , Figure 2 As shown, the composite left-hand and right-hand branches are composed of a series interdigital capacitor 9 and a parallel branch line inductor 8 of a microstrip structure.

[0034] Specific solution: The series interdigital capacitor 9 includes eight right-angled microstrip branches, wherein the first and the eighth right-angled microstrip branches are connected to the connecting line at both ends, and the other end is connected to one end of the second or seventh right-angled microstrip branches, and the rest of the right-angled microstrip branches are connected end to end. The parallel branch line inductor 8 is constructed of a broken line inductor, which is composed of eight right-angled slits etched on the metal layer, wherein one end of the first right-angled slit is connected to the second right-angled slit, the end of the last right-angled slit is open, and the rest of the right-angled slits are connected end to end.

[0035] like Figure 1 , Figure 2 As shown, the first annular coupler includes a signal input port Ⅰ3, a signal output port Ⅰ4, a signal isolation port Ⅰ6 and a signal output port Ⅱ41, which are all microstrip transmission lines; one end of the signal input port Ⅰ3, the signal output port Ⅰ4, the signal isolation port Ⅰ6 and the signal output port Ⅱ41 are connected to form a circular transmission line with a gap; wherein, the gap between the signal input port Ⅰ3 and the signal output port Ⅰ4 is loaded with a composite left-handed transmission line 5 composed of SMT patches, which is used to achieve a phase lead of the signal input port Ⅰ at the signal output port Ⅰ4 by 90 degrees, and a phase lag of the signal input port Ⅰ at the signal output port Ⅱ41 by 90 degrees, so that the phase difference between the signal output port Ⅰ4 and the signal output port Ⅱ41 is 180 degrees, so that the two columns of signals pass through the same When the path reaches the signal isolation port Ⅰ6, the signals can be cancelled.

[0036] like Figure 1As shown, the second annular coupler includes a signal input port II10, a signal output port III12, a signal isolation port II13 and a signal output port IV14, which are all microstrip transmission lines; one end of the signal input port II10, the signal output port III12, the signal isolation port II13 and the signal output port IV14 are connected to form a circular transmission line with a gap; wherein the gap between the signal output port III12 and the signal output port IV14 is loaded with a composite left-handed transmission line 5 composed of SMT patches, which is used to realize that the signal of the signal output port IV14 leads the signal output port III by 90 degrees, and the signal from the signal isolation port II13 lags behind by 90 degrees in phase.

[0037] like Figure 1 As shown, no SMT patch components are loaded in the second annular coupler. This is because the signal is input from the signal input port Ⅰ3, and two columns of signals with a phase difference of 180 are obtained on the two connecting lines 7. When they reach the signal input port Ⅱ10 of the second annular coupler, they cancel each other. The canceling signals are respectively transmitted through Path 11 reaches the signal output port III12 and the signal isolation port II13, so under ideal conditions, the signal output port III12 and the signal isolation port II13 can obtain two near-zero transmission signals; a composite left-handed and right-handed transmission line of the SMT patch is also loaded between the signal output port III12 and the signal output port IV14 of the second ring coupler to achieve the signal of the signal output port IV14 leading the signal output port III by 90 degrees, while the signal from the signal isolation port II13 lags in phase by 90 degrees, so the two beams of signals arriving at the signal output port IV14 can still be offset, and the end of the signal output port IV14 is open circuited or loaded with a fan-shaped radiation surface.

[0038] like Figure 2 As shown, the second annular coupler includes a signal input port III15, a signal output port V16, a signal isolation port III17 and a signal output port VI18, which are all microstrip transmission lines; one end of the signal input port III15, the signal output port V16, the signal isolation port III17 and the signal output port VI18 are connected to form a circular transmission line, and there is still no signal output at the signal output port VI18. At this time, the entire sensor will have three signal cancellation ports, a signal input port and a signal output port. In particular, a fan-shaped radiation surface or an open circuit structure can be loaded at the signal output port VI18. If the second annular coupler adopts a traditional structure, the size of the entire annular coupler is one wavelength, and the distance between each port is The size of the sensor will increase, but the second ring coupler avoids the need for SMT patch components.

[0039] In order to facilitate the detection of the dielectric properties of microfluids, Figure 1The two test areas shown in the figure are provided with microfluidic channels, which include a PDMS layer with a thickness of 3 mm, a width of 2.5 mm and a length of 3.0 mm, respectively. At the same time, a fluid inlet and outlet are provided on the microfluidic channel, and the inlet and outlet are connected to the PDMS with a low-loss polytetrafluoroethylene tube. During the test, the input port and the output port (i.e., the signal input port Ⅰ3 and the signal output port Ⅳ14) of the sensor are connected. Figure 1 As shown in the figure, they are connected to the vector network analyzer respectively, and the object to be tested is injected into the inlet of the microfluidic channel by a propeller, and the sample is pushed out from the outlet at a certain interval, and then the microfluidic channel is cleaned with deionized water, and another sample is tested after drying.

[0040] The object of the present invention for detecting the dielectric properties of microfluids and their minute changes is the minute changes in the temperature, concentration or internal structure of the microfluid or the fluid being tested, and the detection principle is to analyze the phase changes of the transmission parameters of the two ports before and after the detection device is loaded with the object being tested. Since the detection device proposed by the present invention eliminates the background noise by the signal cancellation technology when the object being tested is not loaded, and the composite left and right branches are loaded in the test area to increase the electric field of the test area and reduce the volume of the object being tested, it can sensitively perceive the weak signal caused by extremely small samples in a wide band, and the sensor can be set as a dual-port, three-port, four-port and five-port test device according to the test requirements, and has great tunability.

[0041] Figure 3 The transmission parameters of the detection device with three ports and without the object to be measured are given. It can be seen from the figure that the transmission parameters of the detection device proposed by the present invention are about lower than -20dB in the range of 1GHz to 4GHz, and the reflection coefficient is about lower than -15dB. When the reference object is the same as the object to be measured, the transmission parameters of the sensor will not change. When the object to be measured is different from the reference object, the transmission parameters will change. This change is mainly manifested in the frequency offset and amplitude change of the transmission parameters generated according to the difference in dielectric properties between the object to be measured and the reference object. Figure 4 and 5 shown. Figure 4 and Figure 5 The changes in the calculated transmission parameters when only a high-loss sample (dielectric constants of 15 and 20, loss tangents of 0.2 and 0.4) is loaded in the test area are given. The shift in the frequency and the change in the amplitude of the transmission parameters reflect the differences in the real and imaginary parts of the dielectric properties between the object under test and the reference object, respectively.

[0042] In summary, the multi-port broadband destructive sensor based on composite left-handed and right-handed transmission lines provided by the present invention has many novel advantages when used for detecting the dielectric properties of microfluids and their slight changes: the invention belongs to an integrated, miniaturized, broadband and multi-port structure; the structure proposed by the present invention may include two or three signal destructive ports, while the existing microwave interferometer generally includes one signal destructive port, and multiple signal destructive ports can obtain more information about the object being measured, making the extraction of the dielectric properties of the object being measured more accurate; by loading series interdigitated capacitors and parallel branch line inductance branches in the test area, the volume of the fluid being measured can be greatly reduced, and the technology can be effectively applied to applications in the fields of cytology, electromagnetic field biomedicine, microwave chemical non-thermal effects and protein thermal denaturation; and the device has high sensitivity, wide bandwidth, simple detection method, easy integration, and has the potential to be combined with other devices into a micro-analysis system. The device proposed by the present invention is a multi-port measurement, which can avoid the problem of multiple solutions, so the information capture results of slight changes in the dielectric properties of the fluid are more accurate and more reliable.

[0043] In the description provided herein, a large number of specific details are described. However, it is understood that embodiments of the present invention can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0044] In addition, those skilled in the art will understand that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments also means being within the scope of protection of the present invention and forming different embodiments. For example, in the above embodiments, those skilled in the art can use them in combination according to the known technical solutions and the technical problems to be solved by this application.

[0045] The above is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this patent can make some changes or modify the technical contents suggested above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the solution of the present invention.

Claims

1. A multi-port broadband destructive sensor based on composite left-handed and right-handed transmission lines, characterized in that: It includes a first annular coupler, a second annular coupler and two connecting lines; The first annular coupler and the second annular coupler each include a signal input port, two signal output ports and a signal isolation port; The two signal output ports of the first annular coupler have opposite phases, and the two signal output ports of the second annular coupler have in-phase phases; The two ends of the two connecting lines are respectively connected to the two signal output ports of the first annular coupler and the signal input port of the second annular coupler. The other three ports of the first and second annular couplers are set as ports of the sensor or end-loaded with matching loads according to requirements, so that the sensor can be freely tuned between two ports, three ports, four ports and five ports. Composite left-hand and right-hand branches are loaded in two connecting lines respectively, which are used as test areas. A microfluidic channel is arranged in the test area, and the microfluidic channel is provided with an inlet and an outlet for a liquid sample; The first annular coupler comprises a signal input port I, a signal output port I, a signal isolation port I and a signal output port II; One end of the signal input port I, signal output port I, signal isolation port I and signal output port II are connected to form a circular transmission line with a notch; Wherein, a composite left-handed transmission line composed of SMT patches is loaded at the gap between the signal input port I and the signal output port I, so as to realize that the phase at the signal output port I leads the signal input port I by 90 degrees, and the phase at the signal output port II lags the signal input port I by 90 degrees, so that the phase difference between the signal output port I and the signal output port II is 180 degrees; The second annular coupler comprises a signal input port II, a signal output port III, a signal isolation port II and a signal output port IV; One end of the signal input port II, the signal output port III, the signal isolation port II and the signal output port IV are connected to form a circular transmission line with a notch; The gap between the signal output port III and the signal output port IV is loaded with a composite left-hand and right-hand transmission line composed of SMT patches, which is used to realize that the signal of the signal output port IV leads the signal output port III by 90 degrees, and the signal coming from the signal isolation port II lags behind by 90 degrees in phase; During the test, the input port and output port of the sensor are connected to the vector network analyzer respectively. At the same time, the object to be tested is injected into the inlet of the microfluidic channel by a propeller, and the sample is pushed out from the outlet at a predetermined interval. The microfluidic channel is then cleaned with deionized water, dried, and then another sample is tested.

2. The multi-port broadband destructive sensor based on composite left-handed and right-handed transmission lines according to claim 1, characterized in that: The composite left-hand and right-hand branches are composed of a series interdigitated capacitor and a parallel branch line inductor of a microstrip structure.

3. The multi-port broadband destructive sensor based on composite left-handed and right-handed transmission lines according to claim 2, characterized in that: The series interdigital capacitor includes eight right-angled microstrip branches, wherein the first and eighth right-angled microstrip branches are connected to connecting lines at both ends, and the other ends are connected to one end of the second or seventh right-angled microstrip branches, and the remaining right-angled microstrip branches are connected end to end.

4. The multi-port broadband destructive sensor based on composite left-handed and right-handed transmission lines according to claim 2, characterized in that: The parallel branch line inductor is constructed of a zigzag inductor, which is composed of eight right-angled slits etched on a metal layer, wherein one end of the first right-angled slit is connected to the second right-angled slit, the end of the last right-angled slit is open, and the remaining right-angled slits are connected end to end.

5. The multi-port broadband destructive sensor based on composite left-handed and right-handed transmission lines according to claim 1, characterized in that: The microfluidic channel comprises a PDMS layer having a thickness of 3 mm, a width of 2.5 mm and a length of 3.0 mm; The inlet and outlet of the microfluidic channel are connected to the PDMS by using low-loss polytetrafluoroethylene tubes.

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