阅读说明：本技术 基于复合左右手传输线的多端口宽带相消型传感器 (Multi-port broadband cancellation type sensor based on composite left-right-hand transmission line ) 是由 刘伟娜 任学尧 张俊杰 于 2021-08-26 设计创作，主要内容包括：本发明公开了基于复合左右手传输线的多端口宽带相消型传感器,包括第一环形耦合器、第二环形耦合器和两个连接线；两个连接线的两端分别与第一环形耦合器的两个信号输出端口及第二环形耦合器的信号输入端口相连,第一、二环形耦合器的另外三个端口可根据需求设置为传感器的端口或者末端加载匹配负载,从而使得传感器能够在双端口、三端口、四端口及五端口之间自由调谐；在两个连接线的中分别加载了复合左右手支节,用作测试区域使用,在测试区域设置有微流通道,微流通道设置有液体样品的进口和出口。本发明灵敏度高,频带宽,检测方法简单,易于集成,具有与其他装置组合成微型分析系统的潜质。(The invention discloses a multi-port broadband cancellation type sensor based on a composite left-right-hand transmission line, which comprises a first annular coupler, a second annular coupler and two connecting lines, wherein the first annular coupler is connected with the first annular coupler; two ends of the two connecting wires are respectively connected with two signal output ports of the first annular coupler and a signal input port of the second annular coupler, and the other three ports of the first annular coupler and the second annular coupler can be set as ports of the sensor or terminals of the first annular coupler and the second annular coupler to load matching loads according to requirements, so that the sensor can be freely tuned among the two ports, the three ports, the four ports and the five ports; the composite left and right hand support sections are loaded in the two connecting lines respectively and used as a testing area, a micro-flow channel is arranged in the testing area, and the micro-flow channel is provided with an inlet and an outlet of a liquid sample. The invention has high sensitivity, wide frequency band, simple detection method and easy integration, and has the potential of being combined with other devices into a miniature analysis system.)

1. Multiport broadband cancellation type sensor based on compound right-left hand transmission line, its characterized in that:

the device comprises a first annular coupler, a second annular coupler and two connecting wires;

the first ring coupler and the second ring coupler respectively comprise a signal input port, two signal output ports and a signal isolation port;

the two signal output ports of the first ring coupler have opposite phases, and the two signal output ports of the second ring coupler have in-phase phases;

two ends of the two connecting wires are respectively connected with two signal output ports of the first annular coupler and a signal input port of the second annular coupler, and the other three ports of the first annular coupler and the second annular coupler can be set as ports of the sensor or terminals of the first annular coupler and the second annular coupler to load matching loads according to requirements, so that the sensor can be freely tuned among the two ports, the three ports, the four ports and the five ports;

the composite left and right hand support sections are loaded in the two connecting lines respectively and used as a testing area, a micro-flow channel is arranged in the testing area, and the micro-flow channel is provided with an inlet and an outlet of a liquid sample.

2. The multi-port broadband cancellation-type sensor based on composite left-right-handed transmission lines of claim 1, wherein:

the first ring coupler comprises a signal input port I, a signal output port I, a signal isolation port I and a signal output port II;

one ends 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 round transmission line with a notch;

the composite left-right-hand transmission line formed by SMT patches is loaded at the notch between the signal input port I and the signal output port I and used for achieving that the phase at the signal output port I is advanced by 90 degrees through the signal input port I and the phase at the signal output port II is delayed by 90 degrees through the signal input port I, and therefore the phase difference between the signal output port I and the signal output port II is 180 degrees.

3. The multi-port broadband cancellation-type sensor based on composite left-right-handed transmission lines of claim 1, wherein:

the second ring 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, one end of the signal output port III, one end of the signal isolation port II and one end of the signal output port IV are connected to form a round transmission line with a notch;

the composite left-right hand transmission line formed by SMT patches is loaded in a gap between the signal output port III and the signal output port IV, and is used for enabling a signal of the signal output port IV to lead the signal output port III by 90 degrees, and enabling a signal from the signal isolation port II to lag the phase by 90 degrees.

4. The multi-port broadband cancellation-type sensor based on composite left-right-handed transmission lines of claim 1, wherein:

the second ring coupler comprises a signal input port III, a signal output port V, a signal isolation port III and a signal output port VI;

one ends 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 transmission lines of-90 degrees, and the remaining one port is a transmission line of-270 degrees.

5. The multi-port broadband cancellation-type sensor based on composite left-right-handed transmission lines of claim 1, wherein:

the composite left-right hand support section consists of a series interdigital capacitor and a parallel branch line inductor which are of microstrip structures.

6. The multi-port broadband cancellation-type sensor based on composite left-right hand transmission lines according to claim 5, wherein:

the series interdigital capacitor comprises eight microstrip branches turning at right angles, wherein two ends of the first and eighth microstrip branches turning at right angles are respectively connected with the connecting line, the other ends of the first and eighth microstrip branches turning at right angles are connected with one end of the second or seventh microstrip branch turning at right angles, and the rest microstrip branches turning at right angles are connected end to end.

7. The multi-port broadband cancellation-type sensor based on composite left-right hand transmission lines according to claim 5, wherein:

the parallel branch line inductor is constructed by a broken line inductor and consists of eight right-angle turning gaps etched on a metal layer, wherein one end of the first right-angle turning gap is connected with the second right-angle turning gap, the tail end of the last right-angle turning gap is open, and the other right-angle turning gaps are connected end to end.

8. The multi-port broadband cancellation-type sensor based on composite left-right-handed transmission lines of claim 1, wherein:

during testing, the input port and the output port of the sensor are respectively connected with the vector network analyzer, an object to be tested is injected into the inlet of the microfluidic channel by the aid of the propeller, the sample is pushed out of the outlet at preset intervals, the microfluidic channel is cleaned by deionized water, and another sample is tested after the microfluidic channel is dried.

9. The multi-port broadband cancellation-type sensor based on composite left-right-handed transmission lines of claim 1, wherein:

the microfluidic channel comprises a PDMS layer, the thickness of the PDMS layer is 3mm, and the width and the length of the PDMS layer are respectively 2.5mm and 3.0 mm;

and the inlet and the outlet on the microfluidic channel are connected with PDMS through low-loss polytetrafluoroethylene tubes.

Technical Field

The invention belongs to the technical field of microwave measurement, and particularly relates to a multi-port broadband cancellation type sensor based on a composite left-right-hand transmission line.

Background

With the reduction of the volume of the object to be detected, the sensitivity of the sensor becomes one of the key design parameters, for example, when components such as cell suspension, particle recombination medium, DNA large biomolecule recombination and the like are detected, the traditional test scheme cannot identify the small change of the components due to the sensitivity. An effective solution is to use a destructive sensor, which uses a signal interference cancellation technique to effectively eliminate the background noise of the transmission line and realize a strong test under a weak background signal. The technology is favored by a plurality of researchers internationally, and the dielectric property of micro samples such as cells is tested. In recent years, more and more researchers have proposed broadband test schemes starting from the first dot-frequency test scheme. It has been reported that The broadband test protocol is The document "Y.Cui and P.Wang, The design and operation of ultra-sensitive and tunable radio-frequency integrators [ J ], IEEE Transactions on Microwave Theory and Technology, 2014,62(12):3172 ″," Kozhevnikov, Alexay, Wireless radio-frequency apparatus for Measurement of devices of radio of devices [ J ]. Measurement Science and Technology,2010,21(4):043001, ", and" Saghatti A P, Batra J S, Kameoka J, A. analysis-technique, 2014: "The broadband test protocol is a very good solution for broadband analysis and analysis [ J ]," IEEE transaction and technique, I.S.: I.A. analysis-parameter, I.S., "I.A. A. analysis-device [ J ]," I.S., "I.S. A. The broadband test protocol and operation of Microwave-frequency interaction, I.S.," The integration of micro-frequency instruments [ J., "I.S.," The integration of broadband test protocol, I.S. "I. 1. for achieving The integration of broadband test protocol and The integration of micro-frequency of The integration of The broadband test protocol [ I.S.," I.S. "I. 1. The integration of broadband test protocol, I.S.," I. The integration of broadband test protocol, I.S., "I. The integration of broadband test protocol, I. The integration of broadband test protocol, The integration of broadband test protocol, The integration of The broadband test protocol, The broadband test protocol, most of the schemes are dual-port tests, and multi-frequency, broadband and miniaturization technologies are the constant research subjects in the field of microwave tests, so that the provision of a high-sensitivity broadband and multi-frequency detection scheme is one of the important means for exploring the interaction mechanism of microwaves and media.

In recent years, due to the continuous development of microwave technology, especially the rapid development based on the composite right-hand and left-hand transmission line, a new opportunity is provided for the new breakthrough of various information elements, and the wide attention is drawn to various industries. The characteristics of the electromagnetic super-medium, such as sub-wavelength resonance, negative refraction, perfect lens, energy convergence, surface wave inhibition and the like, enable the electromagnetic super-medium to be popular with researchers in the field of microwave testing. In the microwave testing field, the test bandwidth of the microwave device can be widened, the size of the device can be reduced, the test sensitivity can be improved and the like by introducing the composite left-right-hand transmission line.

In view of this, the invention provides a novel cancellation type sensor, which is a bandwidth-enhanced ring coupler constructed based on a hybrid left-right-hand transmission line, belongs to a multi-port testing device with tunable ports, and can be set into a dual port, a three port, a four port and a five port according to requirements. Due to the introduction of the composite left-right hand transmission line in the design process, the broadband multiport microwave sensor can be in a symmetrical state, so that the size of the device is reduced, and the device has the advantages of low profile, miniaturization, convenience in processing, low price, easiness in integration and the like. In addition, the composite left and right hand support sections are loaded in the test area of the sensor, so that the electric field of the test area is enhanced, and the test sensitivity is further improved.

Disclosure of Invention

Aiming at the problems of narrow bandwidth, large size and the like existing in the existing destructive sensor, the invention aims to provide a multi-port broadband destructive sensor based on a composite left-right-hand transmission line, which can sensitively sense the dielectric property of microfluid and the tiny change of the dielectric property.

The invention is realized according to the following technical scheme:

the multi-port broadband cancellation type sensor based on the composite left-right hand transmission line comprises a first annular coupler, a second annular coupler and two connecting lines; the first ring coupler and the second ring coupler respectively comprise a signal input port, two signal output ports and a signal isolation port; the two signal output ports of the first ring coupler have opposite phases, and the two signal output ports of the second ring coupler have in-phase phases; two ends of the two connecting wires are respectively connected with two signal output ports of the first annular coupler and a signal input port of the second annular coupler, and the other three ports of the first annular coupler and the second annular coupler can be set as ports of the sensor or terminals of the first annular coupler and the second annular coupler to load matching loads according to requirements, so that the sensor can be freely tuned among the two ports, the three ports, the four ports and the five ports; the composite left and right hand support sections are loaded in the two connecting lines respectively and used as a testing area, a micro-flow channel is arranged in the testing area, and the micro-flow channel is provided with an inlet and an outlet of a liquid sample.

The preferable scheme is as follows: 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 which are microstrip transmission lines; one ends 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 round transmission line with a notch; the composite left-right-hand transmission line formed by SMT patches is loaded at the notch between the signal input port I and the signal output port I and used for achieving that the phase at the signal output port I is advanced by 90 degrees through the signal input port I and the phase at the signal output port II is delayed by 90 degrees through the signal input port I, and therefore the phase difference between the signal output port I and the signal output port II is 180 degrees.

The preferable scheme is as follows: 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 which are all microstrip transmission lines; one end of the signal input port II, one end of the signal output port III, one end of the signal isolation port II and one end of the signal output port IV are connected to form a round transmission line with a notch; the composite left-right hand transmission line formed by SMT patches is loaded in a gap between the signal output port III and the signal output port IV, and is used for enabling a signal of the signal output port IV to lead the signal output port III by 90 degrees, and enabling a signal from the signal isolation port II to lag the phase by 90 degrees.

The preferable scheme is as follows: the second ring coupler comprises a signal input port III, a signal output port V, a signal isolation port III and a signal output port VI which are all microstrip type transmission lines; one ends 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 transmission lines of-90 degrees, and the remaining one port is a transmission line of-270 degrees.

The preferable scheme is as follows: the composite left-right hand support section consists of a series interdigital capacitor and a parallel branch line inductor which are of microstrip structures.

The preferable scheme is as follows: the series interdigital capacitor comprises eight microstrip branches turning at right angles, wherein two ends of the first and eighth microstrip branches turning at right angles are respectively connected with the connecting line, the other ends of the first and eighth microstrip branches turning at right angles are connected with one end of the second or seventh microstrip branch turning at right angles, and the rest microstrip branches turning at right angles are connected end to end.

The preferable scheme is as follows: the parallel branch line inductor is constructed by a broken line inductor and consists of eight right-angle turning gaps etched on a metal layer, wherein one end of the first right-angle turning gap is connected with the second right-angle turning gap, the tail end of the last right-angle turning gap is open, and the other right-angle turning gaps are connected end to end.

The preferable scheme is as follows: during testing, the input port and the output port of the sensor are respectively connected with the vector network analyzer, an object to be tested is injected into the inlet of the microfluidic channel by the aid of the propeller, the sample is pushed out of the outlet at preset intervals, the microfluidic channel is cleaned by deionized water, and another sample is tested after the microfluidic channel is dried.

The preferable scheme is as follows: the microfluidic channel comprises a PDMS layer, the thickness of the PDMS layer is 3mm, and the width and the length of the PDMS layer are respectively 2.5mm and 3.0 mm; and the inlet and the outlet on the microfluidic channel are connected with PDMS through low-loss polytetrafluoroethylene tubes.

The invention has the beneficial effects that:

the multi-port broadband cancellation type sensor based on the composite left-right hand transmission line has many novel advantages when being used for detecting the dielectric property and the tiny change of the dielectric property of microfluid: the invention belongs to an integrated, miniaturized, broadband and multiport structure; the structure provided by the invention can comprise two or three signal cancellation ports, the existing microwave interferometer generally comprises one signal cancellation port, and a plurality of signal cancellation ports can obtain more information of the object to be measured, so that the dielectric property of the object to be measured can be more accurately extracted; the volume of the fluid to be tested can be greatly reduced by loading the serial interdigital capacitor and the parallel branch line inductance branch node in the test area, and the technology is effectively suitable for application in the fields of cytology, electromagnetic field biomedicine, microwave chemical non-thermal effect, protein thermal denaturation and the like; the device has the advantages of high sensitivity, wide frequency band, simple detection method and easy integration, has the potential of being combined with other devices into a micro analysis system, can avoid the problem of multiple solutions due to the double-port measurement, and has more accurate and reliable information capture result of tiny change of fluid dielectric characteristics.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention without limiting the invention to the right. It is obvious that the drawings in the following description are only some embodiments, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

In the drawings:

FIG. 1 is a preferred embodiment of a multi-port broadband cancellation type sensor of the present invention;

FIG. 2 is another preferred embodiment of the multi-port broadband destructive sensor of the present invention;

FIG. 3 is a graph of the transport parameters of the present invention prior to loading the microfluid;

FIG. 4 shows the transmission parameter S of the present invention when only a high loss sample is loaded in the test area₂₁A schematic diagram;

FIG. 5 shows the transmission parameter S of the present invention when only a high loss sample is loaded in the test area₃₁Schematic representation.

The attached drawings are as follows: 1-ground plane, 2-dielectric layer, 3-signal input port I, 4-signal output port I, 41-signal output port II, 5-composite left-right hand transmission line, 6-signal isolation port I, 7-connectionConnection, 8-shunt branch inductance, 9-series interdigital capacitance, 10-signal input ports II, 11-12-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.

It should be noted that the drawings and the description are not intended to limit the scope of the inventive concept in any way, but to illustrate it by a person skilled in the art with reference to specific embodiments.

Detailed Description

In order to make the objects, 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 with reference to the drawings in the embodiments of the present invention, and the following embodiments are used for illustrating the present invention and are not intended to limit the scope of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

As shown in figures 1 and 2 of the drawings,the multi-port broadband cancellation type sensor based on the composite left-right hand transmission line comprises a ground plane 1, a medium layer 2, a first annular coupler, a second annular coupler and two connecting lines 7, wherein the first annular coupler, the second annular coupler and the two connecting lines are distributed on the medium layer 2; the first ring coupler and the second ring coupler respectively comprise a signal input port, two signal output ports and a signal isolation port, and the characteristic impedance of all the ports is 50 ohms; the two signal output ports of the first ring coupler have opposite phases and the two signal output ports of the second ring coupler have in-phase phases; two ends of the two connecting wires 7 are respectively connected with two signal output ports of the first annular coupler and a signal input port of the second annular coupler, and the other three ports of the first annular coupler and the second annular coupler can be set as ports of the sensor or terminals of the sensor to load matching loads according to requirements, so that the sensor can be freely tuned among the two ports, the three ports, the four ports and the five ports; total length of first and second ring couplersThe length between each port isThe two connecting lines 7 are respectively loaded with a composite left-right hand branch joint which is used as a test area, the test area is provided with a microflow channel, and the microflow channel is provided with an inlet and an outlet of a liquid sample. Therefore, the scheme realizes broadband high-sensitivity detection from two technical layers, on one hand, the background noise of the transmission line is eliminated by adopting destructive interference, on the other hand, the composite left-right hand transmission line is loaded in the test area to enhance the electric field of the transmission line, and the interaction between the microwave and the object to be tested is enhanced.

The conventional second ring coupler is composed of three sections of right-hand transmission lines with-90 degree phase shift and one section of right-hand transmission lines with-270 degree phase shift, while the second ring coupler used in the present invention is a 90 degree composite left-hand and right-hand transmission line replacing the-270 degree right-hand transmission line of the conventional ring coupler, the replacement does not change the phase difference between the output ports, the only difference is that the bandwidth of the conventional ring coupler is changed, and particularly, the composite left-hand and right-hand transmission lines are realized by SMT patch.

By the design scheme, related parameters are optimized, the provided sensor can realize the test of 1GHz-4GHz, when a tested sample is placed on a test area, the transmission coefficient and the cancellation frequency band of the sensor shift, and the change of the amplitude of the transmission coefficient and the cancellation frequency reflects the loss tangent of the dielectric property and the change of the real part of the dielectric property of a tested object. The invention designs the bandwidth-enhanced microwave interferometer by utilizing the transmission principle of microwaves, and the designed circuit and the micro-flow channel of the test area enable a tested object to fully influence the transmission of electromagnetic waves, so the detection sensitivity of the device can be greatly improved. The detection device is subjected to numerical simulation through a finite element algorithm, experimental results show that the device can realize signal cancellation in a frequency band of 1GHz-4GHz, and a microwave interferometer can sensitively sense weak information caused by nano-liter micro-fluid in a broadband through a composite left-right hand transmission line stub loaded in a test area.

As shown in fig. 1 and 2, the composite left and right hand-support sections are composed of series interdigital capacitors 9 and parallel branch line inductors 8 with microstrip structures.

The specific scheme is as follows: the series interdigital capacitor 9 comprises eight microstrip branches turning at right angles, wherein two ends of the first and eighth microstrip branches turning at right angles are respectively connected with the connecting line, the other ends of the first and eighth microstrip branches turning at right angles are connected with one end of the second or seventh microstrip branch turning at right angles, and the rest microstrip branches turning at right angles are connected end to end. The parallel branch line inductor 8 is constructed by a broken line inductor and consists of eight right-angle turning gaps etched on a metal layer, wherein one end of the first right-angle turning gap is connected with the second right-angle turning gap, the tail end of the last right-angle turning gap is open, and the other right-angle turning gaps are connected end to end.

As shown in fig. 1 and 2, the first ring coupler includes a signal input port i 3, a signal output port i 4, a signal isolation port i 6, and a signal output port ii 41, which are microstrip transmission lines; signal input port I3, signal output port I4, signal isolation port I6 andone end of the signal output port II 41 is connected to form a round transmission line with a notch; the composite right-left-hand transmission line 5 formed by SMT patches is loaded at the gap between the signal input port I3 and the signal output port I4 and used for realizing that the phase at the signal output port I4 is advanced by I90 degrees and the phase at the signal output port II 41 is delayed by I90 degrees, so that the phase difference between the signal output port I4 and the signal output port II 41 is 180 degrees, and therefore the two lines of signals pass through the same phaseWhen the path reaches the signal isolation port I6, the signal can be cancelled.

As shown in fig. 1, the second ring coupler includes a signal input port ii 10, a signal output port iii 12, a signal isolation port ii 13, and a signal output port iv 14, which are microstrip transmission lines; one ends of the signal input port II 10, the signal output port III 12, the signal isolation port II 13 and the signal output port IV 14 are connected to form a round transmission line with a notch; the composite left-right hand transmission line 5 formed by SMT patches is loaded in a gap between the signal output port III 12 and the signal output port IV 14, and is used for enabling a signal of the signal output port IV 14 to lead the signal output port III by 90 degrees, and enabling a signal from the signal isolation port II 13 to lag the phase by 90 degrees.

As shown in FIG. 1, no SMT patch element is loaded in the second ring coupler because the signal is input from the signal input port I3, two columns of signals having a phase difference of 180 are obtained on the two connecting lines 7, and the two columns of signals are cancelled when reaching the signal input port II 10 of the second ring coupler, and the cancellation signals pass through the signal input ports I3 and II 10 of the second ring coupler respectivelyThe path 11 reaches the signal output port iii 12 and the signal isolation port ii 13, so that under an ideal condition, the signal output port iii 12 and the signal isolation port ii 13 can obtain two near-zero transmission signals; between the signal output port III 12 and the signal output port IV 14 of the second ring coupler is also loadedThe composite left-right hand transmission line of the SMT patch realizes that the signal of the signal output port IV 14 leads the signal output port III by 90 degrees, and the signal from the signal isolation port II 13 lags the phase by 90 degrees, so that the two signals reaching the signal output port IV 14 can still be counteracted, and the tail end of the signal output port IV 14 is opened or loaded with a fan-shaped radiation surface.

As shown in fig. 2, the second ring coupler includes a signal input port iii 15, a signal output port v 16, a signal isolation port iii 17, and a signal output port vi 18, which are microstrip-type transmission lines; one end of the signal input port III 15, one end of the signal output port V16, one end of the signal isolation port III 17 and one end of the signal output port VI 18 are connected to form a circular transmission line, no signal output is generated at the position of the signal output port VI 18, at the moment, the whole sensor has three signal cancellation ports, one signal input port and one signal output port, particularly, a fan-shaped radiation surface or an open-circuit structure can be loaded at the position of the signal output port VI 18, if the second ring-shaped coupler adopts a traditional structure, the size of the whole ring-shaped coupler is one wavelength, and the space between the ports is a space with one wavelengthThe size of the sensor increases but the second loop coupler circumvents the SMT patch element.

In order to facilitate the detection of the dielectric property of the microfluid, two test areas shown in fig. 1 are provided with a microfluidic channel, the microfluidic channel comprises a PDMS layer, the thickness of the PDMS layer is 3mm, the width and the length of the PDMS layer are respectively 2.5mm and 3.0mm, the microfluidic channel is provided with an inlet and an outlet of fluid, the inlet and the outlet of the microfluidic channel are connected with the PDMS by adopting low-loss polytetrafluoroethylene tubes, an input port and an output port (namely a signal input port i 3 and a signal output port iv 14) of a sensor (shown in fig. 1) are respectively connected with a vector network analyzer during testing, a tested object is injected into the inlet of the microfluidic channel by adopting a propeller, the sample is pushed out from the outlet at certain intervals, then the microfluidic channel is cleaned by deionized water, and then another sample is tested after drying.

The invention relates to a micro-fluid dielectric property and micro-change detection object, which is micro-fluid or micro-change of temperature, concentration or internal structure of a detected fluid. The detection device provided by the invention eliminates background noise by a signal cancellation technology when a tested object is not loaded, and loads the composite left and right hand support sections in the test area, so that the electric field of the test area is improved, and the volume of the tested object is reduced, therefore, weak signals caused by tiny samples can be sensitively sensed in a broadband, and the sensor can be set into two-port, three-port, four-port and five-port test devices according to test requirements, so that the detection device has great tunability.

Fig. 3 shows the transmission parameter condition when the detecting device is three-port and the object to be detected is not loaded, and it can be seen from the figure that the transmission parameter of the detecting device provided by the invention is about lower than-20 dB and the reflection coefficient is about lower than-15 dB in the range of 1GHz to 4 GHz. When the reference object is the same as the measured object, the transmission parameters of the sensor are not changed. When the measured object is different from the reference object, the transmission parameter changes, which is mainly reflected in that the frequency shift and amplitude change of the transmission parameter are generated according to the difference of the dielectric characteristics of the measured object and the reference object as shown in fig. 4 and 5. Fig. 4 and 5 show the calculated changes in the transmission parameter, the shift in frequency and the change in amplitude of the transmission parameter reflecting the difference between the real part and the imaginary part of the dielectric properties between the object to be measured and the reference object, respectively, only when a certain high-loss sample (dielectric constants of 15 and 20, loss tangents of 0.2 and 0.4) is loaded on the test area.

In conclusion, the multi-port broadband cancellation type sensor based on the composite left-right-hand transmission line provided by the invention has many novel advantages when being used for detecting the dielectric property and the tiny change of the dielectric property of microfluid: the invention belongs to an integrated, miniaturized, broadband and multiport structure; the structure provided by the invention can comprise two or three signal cancellation ports, the existing microwave interferometer generally comprises one signal cancellation port, and a plurality of signal cancellation ports can obtain more information of the object to be measured, so that the dielectric property of the object to be measured can be more accurately extracted; the volume of the fluid to be tested can be greatly reduced by loading the serial interdigital capacitor and the parallel branch line inductance branch node in the test area, and the technology is effectively suitable for application in the fields of cytology, electromagnetic field biomedicine, microwave chemical non-thermal effect, protein thermal denaturation and the like; the device is high in sensitivity, wide in frequency band, simple in detection method and easy to integrate, has the potential of being combined with other devices to form a micro analysis system, can avoid the problem of multiple solutions due to the fact that the device is multi-port measurement, and therefore the information capture result of the tiny change of the dielectric property of the fluid is more accurate and reliable.

In the description provided herein, numerous specific details are set forth. It is understood, however, that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

Furthermore, those skilled in the art will appreciate that while some embodiments described herein include some features included in other embodiments, rather than others, combinations of features of different embodiments are also meant to be within the scope of the invention and form different embodiments. For example, in the above embodiments, those skilled in the art can use the combination according to the known technical solutions and technical problems to be solved by the present application.

Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.