CN113959564B - Temperature compensated microstrip sensor for microfluidics - Google Patents
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- 239000007788 liquid Substances 0.000 claims abstract description 63
- 239000000758 substrate Substances 0.000 claims abstract description 36
- 230000000295 complement effect Effects 0.000 claims abstract description 26
- 238000012360 testing method Methods 0.000 claims abstract description 25
- 239000004205 dimethyl polysiloxane Substances 0.000 claims abstract description 18
- 229920000435 poly(dimethylsiloxane) Polymers 0.000 claims abstract description 18
- 238000002347 injection Methods 0.000 claims abstract description 10
- 239000007924 injection Substances 0.000 claims abstract description 10
- 238000004987 plasma desorption mass spectroscopy Methods 0.000 claims abstract description 6
- 238000005530 etching Methods 0.000 claims abstract description 4
- 235000013870 dimethyl polysiloxane Nutrition 0.000 claims abstract 5
- CXQXSVUQTKDNFP-UHFFFAOYSA-N octamethyltrisiloxane Chemical compound C[Si](C)(C)O[Si](C)(C)O[Si](C)(C)C CXQXSVUQTKDNFP-UHFFFAOYSA-N 0.000 claims abstract 5
- 238000012549 training Methods 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 239000012530 fluid Substances 0.000 claims description 8
- 230000000694 effects Effects 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 6
- 230000035945 sensitivity Effects 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 3
- 230000007613 environmental effect Effects 0.000 description 10
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- 238000013528 artificial neural network Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- -1 Polydimethylsiloxane Polymers 0.000 description 3
- 230000005684 electric field Effects 0.000 description 3
- 238000010801 machine learning Methods 0.000 description 3
- 230000002093 peripheral effect Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 2
- 230000002068 genetic effect Effects 0.000 description 2
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- 238000003062 neural network model Methods 0.000 description 2
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- 230000001419 dependent effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
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- GBMDVOWEEQVZKZ-UHFFFAOYSA-N methanol;hydrate Chemical compound O.OC GBMDVOWEEQVZKZ-UHFFFAOYSA-N 0.000 description 1
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- 238000004088 simulation Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000002277 temperature effect Effects 0.000 description 1
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Abstract
The invention discloses a temperature compensation microstrip sensor for microfluid, which comprises a dielectric substrate, wherein a split ring resonator is etched on the bottom surface of the substrate, and a microstrip part is arranged, the microstrip part comprises two main microstrip lines and two branch microstrip lines, the two branch microstrip lines are enclosed into a rectangular shape, two sides of the two branch microstrip lines respectively form a T-shaped junction with the main microstrip lines on the same side, and the other end of the main microstrip line is a port; etching two complementary split ring resonators on the top layer of the substrate, wherein each branch microstrip line excites one complementary split ring resonator respectively; the complementary split ring resonator is provided with a liquid injection port and a liquid outflow port, and a tortuous groove is etched on the medium substrate between the liquid injection port and the liquid outflow port; the PDMS microfluidic channel substrate is arranged above the two complementary split ring resonators, the PDMS microfluidic channel substrate is provided with a test channel and a reference channel, the test channel and the reference channel are respectively overlapped with and strictly aligned with the zigzag grooves of the two complementary split ring resonators, the reference channel is used as a reference, and the test channel is used for testing when binary mixed liquid is injected.
Description
Technical Field
The invention belongs to the technical field of microwave sensor design, and particularly relates to a temperature compensation microstrip sensor for microfluid.
Background
In the past few years, many microwave sensors based on split-ring resonators (split-ring resonators), complementary split-ring resonators (complementary split-ring resonators) and their modified structures have been proposed for detecting solid matter or binary liquid mixtures.
It is well known that unwanted or uncontrolled ambient environmental factors (e.g. temperature, air pressure and humidity etc.) can affect the dielectric constants of the dielectric substrate of the dielectric, PDMS and the liquid sample, leading to resonant frequency shifts and corresponding measurement errors. In order to suppress the influence of environmental factors, some compensation techniques have been developed. Among them, the differential sensor is based on this, however, although the differential sensor can effectively suppress environmental influence, it cannot recognize the liquid because the dielectric constant of the liquid is highly dependent on temperature. Microwave sensors have recently emerged that employ machine learning algorithms to eliminate temperature effects in SRR based applications. However, the compiling process of the algorithm is complex, and the trained ANN model is only suitable for binary liquids with characteristic parameters trained in advance, so that the application range of the algorithm is greatly limited. Furthermore, this technique cannot exclude other environmental influences than temperature.
Therefore, it is particularly important to develop a microwave microfluidic sensor structure to cope with the above-mentioned problem of complex multi-dimensional environmental variable effects.
Disclosure of Invention
The invention provides a temperature compensation microstrip sensor for microfluid, which can inhibit complex environmental influence and increase SRR structure to detect temperature through an improved differential microwave sensor structure.
In order to solve the technical problems, the invention adopts the following technical scheme:
a temperature compensated microstrip sensor for microfluidics, comprising: a dielectric substrate, a microstrip section, a Split Ring Resonator (SRR), a Complementary Split Ring Resonator (CSRR), and a PDMS microfluidic channel substrate; etching the bottom surface of the dielectric substrate and arranging a microstrip part, wherein the microstrip part comprises two main microstrip lines and two branch microstrip lines, the two branch microstrip lines are enclosed into a rectangular shape, two sides of the two branch microstrip lines respectively form a T-shaped junction with the main microstrip lines on the same side, and the other ends of the two main microstrip lines are respectively provided with a first port and a second port; etching two CSRRs on the top layer of the dielectric substrate, wherein each branch microstrip line excites one CSRR respectively; the Complementary Split Ring Resonator (CSRR) is provided with a liquid injection port and a liquid outflow port, and a tortuous groove is etched on a medium substrate between the liquid injection port and the liquid outflow port; the Polydimethylsiloxane (PDMS) microfluidic channel substrate is arranged above two Complementary Split Ring Resonators (CSRR), and is provided with a test channel and a reference channel, wherein the test channel and the reference channel are respectively overlapped and strictly aligned with the zigzag grooves of the two Complementary Split Ring Resonators (CSRR), the reference channel is used as a reference, and the test channel is used for testing when binary mixed liquid is injected.
Preferably, the dielectric substrate is formed of Rogers RT/Duroid 4350, has a thickness of 0.762mm, a relative dielectric constant of 3.66, and a loss tangent of 0.004. Preferably, a quarter wavelength impedance conversion line with a characteristic impedance of 35.35 ohms is cascaded between two 50 ohm ports and the corresponding T-junction.
Preferably, according to the Maxwell-Garnett expression, the complex dielectric constant of the binary liquid mixture is expressed as follows:
wherein ε m And epsilon f Is the dielectric constant of the host medium and the second liquid, v f Is the volume fraction of the second liquid.
Preferably, the liquid dielectric constant can be described using a single Debye model, which is expressed as follows:
wherein ε 0 (T) and ε ∞ (T) is the dielectric constant in the low frequency and high frequency ranges, respectively, τ (T) represents the relaxation time, and the expression for pure water τ (T) is:
wherein a=1.37×10 -13 s，d＝651℃,T 0 ＝133℃，T water Representing the temperature of the water;
preferably, the temperature has a significant effect on the properties of the liquid, and it is desirable to define the complex permittivity of the liquid at different temperatures according to the Kirkwood theory of pure fluids, the relationship between liquid permittivity and temperature being described as follows:
wherein M is w Represents molecular weight, ρ represents density, α is molecular polarizability, N A Representing the Avogapro constant μ represents the dipole moment, k of the molecule B Representing the boltzmann constant, g characterizes the correlation factor of the relative orientation between adjacent molecules.
Preferably, the temperature may be restored by a change in the resonant frequency of the SRR. A fitted expression is applied to describe the relationship between temperature and resonant frequency as follows:
T＝83.36-452.78f r +1570.76f r 2 -2832.13f r 3
wherein f r Is relative to a reference frequency f ref,SRR The expression of which is as follows:
wherein f SRR Representing the resonant frequency of the SRR at different temperatures, reference frequency f ref,SRR Is set to 1.52GHz;
preferably, in general, the liquid properties can be retrieved by relative resonance frequency shift and normalized quality factor, as follows:
wherein f CSRR,L And Q CSRR,L Respectively expressed as the resonant frequency and the quality factor, f, of the lower leg reference CSRR CSRR,U And Q CSRR,U The resonant frequency and the quality factor of the CSRR of the liquid to be tested added in the upper branch are shown, respectively.
Preferably, the sensitivity of the sensor is defined as:
preferably, a machine learning method is used to retrieve the liquid dielectric constants at different temperatures. A Genetic Algorithm (GA) -based optimized back propagation neural network (BP-NN) is employed to reconstruct the relationship between measured data and fluid properties. In the training process, the GA searches for initial weights, and the BP-NN uses these initial weights to find the optimal solution. According to the kolmogorov law, the node of the hidden layer is set to 10 to shift the frequency f relative to resonance rm And temperature T as input data, liquid dielectric constant ε' r The' real part is taken as output. Weights of the network (w ij V (V) j I=1, 2, j=1, 2, …, 10) and a threshold (t j And a 0 J=1, 2, …, 10) by training data set (f rm And T) is obtained. After NN model is obtained, all training data f rm And T as test data to verify the reliability of the model. Extracting epsilon' r Thereafter, BP-NN is applied to retrieve loss tangent tan. Delta. It has three input variables (. Epsilon.'). r ,T,and Q nor ) And an output variable (tan delta). Similarly, the network weights (w kp And V p K=1, 2,3 and p=1, 2, …, 10) and a threshold (t p and b 0 P=1, 2, …, 10) the data set (epsilon ') was obtained by training' r ,T,Q nor And tan delta). Training data ε 'as above' r T, and Q nor The NN model is also validated as test data.
The beneficial effects of the invention are as follows: the present invention is for a temperature compensated micro-strip sensor for micro-fluid that detects a temperature variable by adding an SRR structure while suppressing a complex environmental impact through an improved differential microwave sensor structure. The invention can realize higher measurement precision and better inhibition effect on environmental impact, and has very positive effect on promoting the industrialization process of the microwave sensor.
Drawings
FIG. 1 is a schematic diagram of a temperature compensated microstrip sensor for microfluidic applications according to an embodiment of the present invention;
FIG. 2 is a top view of a temperature compensated microstrip sensor structure for microfluidic applications according to an embodiment of the present invention;
FIG. 3 is a bottom view of a temperature compensated microstrip sensor structure for microfluidic applications according to an embodiment of the present invention;
FIG. 4 is an equivalent circuit model of a temperature compensated microstrip sensor structure for microfluidic applications in accordance with an embodiment of the present invention;
FIG. 5 is a schematic diagram of one of the neural networks of an embodiment of the present invention;
FIG. 6 is a schematic diagram of one of the neural networks of an embodiment of the present invention;
FIG. 7 is a graph showing experimental results of an embodiment of the present invention.
In the illustration, a 1-medium substrate, a 1-1-zigzag slot, a 2-microstrip part, a 2-1 main microstrip line, a 2-2 branch microstrip line, a 2-1-1-port one, a 20-1-2-port two, a 3-Split Ring Resonator (SRR), a 4-Complementary Split Ring Resonator (CSRR), a 4-1-liquid injection port, a 4-2-liquid outflow port, a 4-3-test channel, a 4-4-reference channel and a 5-PDMS microfluidic channel substrate.
Detailed Description
The invention will now be described in detail with reference to the drawings and examples.
The implementation of the invention provides a temperature compensation type microwave microfluidic sensor, a microstrip part is used for realizing differential sensing, and two symmetrical Complementary Split Ring Resonators (CSRR) 4 are etched on a ground plane. A Polydimethylsiloxane (PDMS) substrate 5 is connected to the ground plane. To enhance the electric field confinement, a meandering slot is added to the CSRR and the microfluidic channel is aligned with the meandering slot. In addition, a Split Ring Resonator (SRR) 3 and peripheral circuits are added to capture the ambient temperature. The extracted temperature, and the changes in the resonant frequency and quality factor of the CSRR are used as input data for training the neural network model. The results show that the predicted dielectric constant of the liquid of the trained neural network is very consistent with the reference value. The sensor provided by the invention has excellent performance, small volume, high sensitivity and temperature compensation capability, and becomes a good candidate in the field of microfluid detection.
Referring to fig. 1-6, the implementation of the present invention provides an improved differential microwave sensor structure to suppress complex environmental effects while adding an SRR structure to detect temperature variations, and fig. 1 is a schematic diagram of a temperature compensated microstrip sensor structure for microfluidic applications according to an embodiment of the present invention, including a dielectric substrate 1, a microstrip section 2, a split-ring resonator 3, a complementary split-ring resonator 4, and a PDMS microfluidic channel substrate 5; the bottom surface of the dielectric substrate 1 is etched with the split ring resonator 3 and is provided with a microstrip part 2, and the split ring resonator 3 is excited by a microstrip line. The microstrip part 2 comprises two main microstrip lines 2-1 and two branch microstrip lines 2-2, the two branch microstrip lines 2-2 are enclosed into a rectangle shape, two sides of the microstrip line form T-shaped junctions with the main microstrip lines 2-1 on the same side respectively, and the other ends of the two main microstrip lines 2-1 are respectively provided with a port I2-1-1 and a port II 2-1-2; the top layer of the dielectric substrate 1 is etched with two complementary split ring resonators 4 excited by microstrip lines. Each branch microstrip line 2-2 excites a complementary split ring resonator respectively; the complementary split ring resonator 4 is provided with a liquid injection port 4-1 and a liquid outflow port 4-2, and a tortuous groove 1-1 is etched on a medium substrate between the liquid injection port 4-1 and the liquid outflow port 4-2; the complementary split ring resonator CSRR employs meandering slots to enhance electric field confinement, which are etched on dielectric substrates, and also serve as sensing regions. The PDMS microfluidic channel substrate 5 is arranged above the two complementary split ring resonators, the PDMS microfluidic channel substrate 5 is provided with a test channel 4-3 and a reference channel 4-4, the test channel 4-3 and the reference channel 4-4 are respectively overlapped and aligned with the zigzag grooves of the two complementary split ring resonators 4 strictly, wherein the reference channel 4-4 is used as a reference, and the test channel 4-3 is used for testing when binary mixed liquid is injected.
In this embodiment, a quarter-wave impedance conversion line with a characteristic impedance of 35.35 ohms is cascaded between port one and port two of 50 ohms and the same side T-junction. The dielectric substrate was formed of Rogers RT/Duroid 4350, and had a thickness of 0.762mm, a relative permittivity of 3.66, and a loss tangent of 0.004.
According to an embodiment of the invention, the proposed sensor is shown in fig. 2 and 3 in top and bottom views, respectively. In order to accurately detect the temperature, SRR with peripheral circuits is added. As shown in fig. 3, the SRR is loaded with a varactor SMV2023 and a thermistor NCP03XH103J05RD. Full wave electromagnetic simulations were performed using commercial software ANSYS HFSS, in which varactors were modeled as lumped elements with different capacitance values. The remaining sensor structure variable parameter values are determined in both fig. 2 and fig. 3.
An equivalent circuit model of the sensor structure of the embodiment of the present invention is shown in fig. 4.
According to an embodiment of the present invention, the complex permittivity of a binary liquid mixture is represented as follows according to the Maxwell-Garnett expression:
wherein ε m And epsilon f Is the dielectric constant of the host medium and the second liquid, v f Is the volume fraction of the second liquid.
According to an embodiment of the invention, the liquid permittivity may be described using a single Debye model, which is represented as follows:
wherein ε 0 (T) and ε ∞ (T) is the dielectric constant in the low frequency and high frequency ranges, respectively, τ (T) represents the relaxation time, and the expression for pure water τ (T) is:
wherein a=1.37×10 -13 s，d＝651℃,T 0 ＝133℃，T water Representing the temperature of the water;
according to the embodiment of the invention, the temperature has a remarkable effect on the liquid property, and the complex dielectric constants of the liquid at different temperatures are required to be clear according to the Kirkwood theory of pure fluid, and the relationship between the liquid dielectric constants and the temperature is described as follows:
wherein M is w Represents molecular weight, ρ represents density, α is molecular polarizability, N A Representing the Avogapro constant μ represents the dipole moment, k of the molecule B Representing the boltzmann constant, g characterizes the correlation factor of the relative orientation between adjacent molecules.
According to an embodiment of the present invention, the temperature may be recovered by a change in the resonant frequency of the SRR. A fitted expression is applied to describe the relationship between temperature and resonant frequency as follows:
T＝83.36-452.78f r +1570.76f r 2 -2832.13f r 3
wherein f r Is relative to a reference frequency f ref,SRR The expression of which is as follows:
wherein f SRR Representing the resonant frequency of the SRR at different temperatures, reference frequency f ref,SRR Is set to 1.52GHz;
in accordance with embodiments of the present invention, in general, liquid properties can be retrieved by relative resonance frequency shift and normalized quality factor, as follows:
wherein f CSRR,L And Q CSRR,L Respectively expressed as the resonant frequency and the quality factor, f, of the lower leg reference CSRR CSRR,U
And Q CSRR,U The resonant frequency and the quality factor of the CSRR of the liquid to be tested added in the upper branch are shown, respectively.
According to an embodiment of the invention, the sensitivity of the sensor is defined as:
according to an embodiment of the invention, a machine learning method is used to retrieve the liquid dielectric constants at different temperatures. A Genetic Algorithm (GA) -based optimized back propagation neural network (BP-NN) is employed to reconstruct the relationship between measured data and fluid properties. In the training process, the GA searches for initial weights, and the BP-NN uses these initial weights to find the optimal solution. According to the kolmogorov law, the node of the hidden layer is set to 10, as shown in fig. 5 and 6, to shift the frequency f at relative resonance rm And temperature T as input data, liquid dielectric constant ε' r The' real part is taken as output. Weights of the network (w ij V (V) j I=1, 2, j=1, 2, …, 10) and a threshold (t j And a 0 J=1, 2, …, 10) by training data set (f rm And T) is obtained. After NN model is obtained, all training data f rm And T as test data to verify the reliability of the model. Extracting epsilon' r Thereafter, BP-NN shown in FIG. 6 was used to search for loss tangent tan. Delta. It has three input variables (. Epsilon.'). r ,T,and Q nor ) And an output variable (tan delta). Similarly, the network weights (w kp And V p K=1, 2,3 and p=1, 2, …, 10) and a threshold (t p and b 0 P=1, 2, …, 10) the data set (epsilon ') was obtained by training' r ,T,Q nor And tan delta). Training data ε 'as above' r T, and Q nor The NN model is also validated as test data.
Fig. 7 shows some experimental results, wherein fig. 7 (a), (b), (c) and (d) show the injection of a set of water-methanol mixtures into the test channels of the proposed sensor at different temperatures, respectively, and the corresponding transmission coefficients obtained are recorded. The temperatures shown in FIGS. 7 (a), (b), (c) and (d) were 20℃and 25℃and 40℃and 50℃respectively. It can be found from fig. 7 that the resonant frequency of the SRR and the reference CSRR hardly change. The resonant frequency of the upper CSRR decreases with increasing water volume fraction in the mixture due to the increasing dielectric constant of the liquid. Notably, the dielectric constants of the substrate and PDMS are also affected by ambient temperature, but these effects can be suppressed to some extent by the differential structure.
The temperature compensation type microwave microfluidic sensor is characterized in that a microstrip part is used for realizing differential sensing, and two symmetrical Complementary Split Ring Resonators (CSRRs) are etched on a ground plane. A Polydimethylsiloxane (PDMS) substrate was connected to the ground plane. To enhance the electric field confinement, a meandering slot is added to the CSRR and the microfluidic channel is aligned with the meandering slot. In addition, a Split Ring Resonator (SRR) and peripheral circuitry are added to capture the ambient temperature. The extracted temperature, and the changes in the resonant frequency and quality factor of the CSRR are used as input data for training the neural network model. The results show that the predicted dielectric constant of the liquid of the trained neural network is very consistent with the reference value. The proposed sensor exhibits excellent performance with small volume, high sensitivity and temperature compensation capability, making it a good candidate for the field of microfluidic detection.
The improved differential microwave sensor of the present invention is proposed to suppress environmental impact and to increase SRR to detect temperature. The retrieved dielectric constant is used with the temperature to identify the Liquid Under Test (LUT). On the other hand, the method plays a very positive role in promoting the industrialization process of the microwave sensor.
The foregoing description is only illustrative of the present invention and is not intended to limit the scope of the invention, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present invention.
Claims (10)
1. A temperature compensated microstrip sensor for microfluidics, comprising: the micro-strip micro-fluidic device comprises a dielectric substrate (1), a micro-strip part (2), a split ring resonator (3), a complementary split ring resonator (4) and a PDMS micro-fluidic channel substrate (5); the bottom surface of the dielectric substrate (1) is etched with the split ring resonator (3) and is provided with a microstrip part (2), the microstrip part (2) comprises two main microstrip lines (2-1) and two branch microstrip lines (2-2), the two branch microstrip lines (2-2) are enclosed into a rectangular shape, two sides of the microstrip lines respectively form T-shaped junctions with the main microstrip lines (2-1) on the same side, and the other ends of the two main microstrip lines (2-1) are respectively provided with a port I (2-1-1) and a port II (2-1-2); etching two complementary split ring resonators (4) on the top layer of the dielectric substrate (1), and respectively exciting one complementary split ring resonator by each branch microstrip line (2-2); the complementary split ring resonator (4) is provided with a liquid injection port (4-1) and a liquid outflow port (4-2), and a tortuous groove (1-1) is etched on a medium substrate between the liquid injection port (4-1) and the liquid outflow port (4-2); the PDMS microfluidic channel substrate (5) is arranged above the two complementary split ring resonators, the PDMS microfluidic channel substrate (5) is provided with a test channel (4-3) and a reference channel (4-4), the test channel (4-3) and the reference channel (4-4) are respectively overlapped and strictly aligned with the zigzag grooves of the two complementary split ring resonators (4), wherein the reference channel (4-4) is used as a reference, and the test channel (4-3) is used for testing when binary mixed liquid is injected.
2. The temperature compensated microstrip sensor for microfluidics according to claim 1, wherein the dielectric substrate is formed of Rogers RT/Duroid 4350, has a thickness of 0.762mm, a relative permittivity of 3.66, and a loss tangent of 0.004.
3. The temperature compensated microstrip sensor for a micro fluid according to claim 1, wherein a quarter wavelength impedance conversion line having a characteristic impedance of 35.35 ohms is cascaded between port one, port two and the same side T-junction of 50 ohms.
4. A temperature compensated microstrip sensor for microfluidics according to any one of claims 1 to 3, wherein the complex permittivity of the binary liquid mixture is expressed as follows according to the Maxwell-Garnett expression:
wherein ε m And epsilon f Is the dielectric constant of the host medium and the second liquid, v f Is the volume fraction of the second liquid.
5. The temperature compensated microstrip sensor for microfluidics of claim 4, wherein the liquid dielectric constant is described using a single Debye model, represented as follows:
wherein ε 0 (T) and ε ∞ (T) is the dielectric constant in the low frequency and high frequency ranges, respectively, τ (T) represents the relaxation time, and the expression for pure water τ (T) is:
wherein a=1.37×10 -13 s，d＝651℃，T 0 ＝133℃，T water Indicating the temperature of the water.
6. The temperature compensated microstrip sensor for microfluidics according to claim 5, wherein the temperature has a significant effect on the properties of the liquid, and wherein the complex permittivity of the liquid at different temperatures is determined according to the Kirkwood theory of pure fluids, and wherein the relationship between the liquid permittivity and temperature is described as follows:
wherein M is w Represents molecular weight, ρ represents density, α is molecular polarizability, N A Representing the Avogapro constant μ represents the dipole moment, k of the molecule B Representing the boltzmann constant, g characterizes the adjacencyCorrelation factors for the relative orientation between molecules.
7. The temperature-compensated microstrip sensor for microfluidics according to claim 6, wherein the temperature is recovered by a change in the resonant frequency of the SRR, and a fitting expression is applied to describe the relationship between the temperature and the resonant frequency as follows:
T＝83.36-452.78f r +1570.76f r 2 -2832.13f r 3
wherein f r Is relative to a reference frequency f ref，SRR The expression of which is as follows:
wherein f SRR Representing the resonant frequency of the SRR at different temperatures, reference frequency f ref，SRR Is set to 1.52GHz.
8. The temperature compensated microstrip sensor for microfluidics according to claim 7, wherein the liquid characteristics are retrieved by relative resonance frequency shift and normalized quality factor as follows:
wherein f CSRR，L And Q CSRR，L Respectively expressed as the resonant frequency and the quality factor, f, of the lower leg reference CSRR CSRR，U And Q CSRR，U The resonant frequency and the quality factor of the CSRR of the liquid to be tested added in the upper branch are shown, respectively.
9. The temperature-compensated microstrip sensor for microfluidics according to claim 8, wherein the sensitivity of the sensor is defined as:
10. the temperature compensated microstrip sensor for a micro-fluid according to claim 9, wherein the node of the hidden layer is set to 10 according to kolmogorov's law to shift the frequency f relative to resonance rm And temperature T as input data, liquid dielectric constant ε' r As output the real part of (2); weights of the network (w ij V (V) j I=1, 2, j=1, 2,..10) and a threshold (t j And a 0 J=1, 2,..10.) by training data set (f rm And T) is obtained; after NN model is obtained, all training data f rm And T as test data to verify the reliability of the model; extracting epsilon' r Thereafter, BP-NN is applied to retrieve loss tangent tan delta; it has three input variables (. Epsilon.'). r ，T，and Q nor ) And an output variable (tan delta); similarly, the network weights (w kp And V p K=1, 2,3 and p=1, 2,..10) and a threshold (t p and b 0 P=1, 2,..10.) the dataset (epsilon') was obtained by training. r ，T，Q nor And tan delta); training data ε 'as above' r T, and Q nor The NN model is also validated as test data.
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2906268A1 (en) * | 2014-09-29 | 2016-03-29 | The Governors Of The University Of Alberta | Apparatus and method for high resolution complex permittivity sensing using high q microwave sensors for lossy or non-lossy mediums and samples |
| KR102016460B1 (en) * | 2018-02-23 | 2019-08-30 | 광운대학교 산학협력단 | Spiral-coupled passive microresonator sensor for sensitive detection and characterization of water-ethanol solution |
| CN110988487A (en) * | 2019-11-27 | 2020-04-10 | 杭州电子科技大学 | Microwave microfluid sensor based on T-shaped feeder line excitation complementary open-loop resonator |
| CN111007322A (en) * | 2019-11-27 | 2020-04-14 | 杭州电子科技大学 | Differential microwave microfluid sensor based on complementary open-loop resonator structure |
| WO2020176857A1 (en) * | 2019-02-28 | 2020-09-03 | American University Of Beirut | Biomarker monitoring sensor and methods of use |
| CN113091941A (en) * | 2021-04-30 | 2021-07-09 | 杭州电子科技大学 | Microfluidic temperature sensing module and temperature characterization method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CA2906268A1 (en) * | 2014-09-29 | 2016-03-29 | The Governors Of The University Of Alberta | Apparatus and method for high resolution complex permittivity sensing using high q microwave sensors for lossy or non-lossy mediums and samples |
| KR102016460B1 (en) * | 2018-02-23 | 2019-08-30 | 광운대학교 산학협력단 | Spiral-coupled passive microresonator sensor for sensitive detection and characterization of water-ethanol solution |
| WO2020176857A1 (en) * | 2019-02-28 | 2020-09-03 | American University Of Beirut | Biomarker monitoring sensor and methods of use |
| CN110988487A (en) * | 2019-11-27 | 2020-04-10 | 杭州电子科技大学 | Microwave microfluid sensor based on T-shaped feeder line excitation complementary open-loop resonator |
| CN111007322A (en) * | 2019-11-27 | 2020-04-14 | 杭州电子科技大学 | Differential microwave microfluid sensor based on complementary open-loop resonator structure |
| CN113091941A (en) * | 2021-04-30 | 2021-07-09 | 杭州电子科技大学 | Microfluidic temperature sensing module and temperature characterization method thereof |
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