Substrate integrated waveguide microwave sensor for glucose detection

Abstract

The invention discloses a substrate integrated waveguide microwave sensor for glucose detection, and aims to solve the problem of low sensitivity of an existing non-invasive glucose sensor. The substrate integrated waveguide microwave sensor for glucose detection comprises an input feeder line, an integrated waveguide and a split ring resonator, the integrated waveguide is a fan-shaped microstrip line, the split ring resonator is arranged in the middle of the fan-shaped microstrip line, the input feeder line is located on the central axis of the integrated waveguide, and the split ring resonator is located in the middle of the integrated waveguide. One end of the input feeder line is located on the outer side of the arc of the integrated waveguide, the other end of the input feeder line extends into the integrated waveguide, and a metalized through hole array is arranged in the circumferential direction of the arc of the integrated waveguide. The SIW structure and the SRR structure are combined to be used for glucose detection, efficient space utilization and excellent electromagnetic characteristics are achieved, the performance and sensitivity of the sensor are remarkably improved, and the sensor shows excellent sensitivity and linear response in the glucose concentration range of 0-1000 mg / dL.

Description

Technical Field

[0001] The invention belongs to the field of microwave sensors, and in particular relates to a substrate integrated waveguide microwave sensor for detecting dielectric properties of liquids. Background Art

[0002] The dielectric constant is a basic parameter that characterizes the electrical properties of materials. It is affected by many factors, such as molecular polarization, molecular structure, and external electric field. The analysis of the dielectric properties of liquids is of great significance in food processing, environmental monitoring, and biomedicine. The existing dielectric property measurement methods, such as electrochemistry, enzymology, and spectroscopy, often require expensive equipment, which limits their promotion in daily applications. Microwave sensors have become an important tool for measuring the dielectric constant of liquids due to their high sensitivity, fast response, and non-contact measurement. Especially in the microwave frequency band, the influence of the polarization mechanism enables microwave sensors to effectively detect the dielectric properties of liquids.

[0003] With the increasing incidence of diabetes worldwide, the demand for portable blood glucose monitoring devices is growing. Traditional blood glucose testing methods usually rely on blood sample analysis, which is invasive and uncomfortable. This has prompted researchers to explore the possibility of non-invasive monitoring technology to improve patient experience and compliance.

[0004] 1. Current status of non-invasive blood glucose monitoring technology:

[0005] Currently, non-invasive blood glucose monitoring technology mainly focuses on the following methods:

[0006] a. Infrared spectroscopy: The concentration is determined by analyzing the absorption characteristics of infrared light in glucose molecules. However, it is greatly affected by environmental factors and lacks sensitivity and accuracy.

[0007] b. Electrochemical sensor: It uses the catalytic reaction of glucose oxidase for detection. Although the technology is mature, it still requires blood sampling and is an invasive method.

[0008] c. Electromagnetic wave technology: Combining microwave, radio frequency and other technologies for blood glucose monitoring has the advantages of non-invasiveness and rapid detection, but still faces challenges in signal processing and sensitivity improvement.

[0009] 2. Market demand:

[0010] The global medical monitoring device market is expected to continue to grow, especially in the field of diabetes management. Non-invasive blood glucose monitoring devices are favored by more and more patients and doctors due to their non-invasive and convenient characteristics. The development of highly sensitive and fast-response sensors can significantly improve the quality of life of patients and improve the effectiveness of blood glucose management.

[0011] 3. Existing patented products

[0012] (1) Patent name: "Advanced continuous analyte monitoring system"

[0013] Patent number: US20210251531A1

[0014] Technical Overview: This patent generally relates to systems and methods for processing, transmitting, and displaying data from a continuous analyte sensor, such as a glucose sensor. In certain embodiments, a continuous analyte sensor system includes a sensor electronics module having energy-saving features. A feature of the module is a low-power measurement circuit that can be switched between a measurement mode and a low-power mode, in which a charging circuit continues to power the electrodes of the sensor. In addition, the sensor electronics module can be switched between a low-power storage mode and a high-power operating mode via a switch. The switch can include, for example, a reed switch or an optical switch. A verification routine can also be implemented to ensure that an interrupt signal sent from the switch is valid. The continuous analyte sensor can be physically connected to the sensor electronics module, which is in direct wireless communication with multiple different display devices.

[0015] (2) Patent Name: "Continuous analyte monitor data recording device operable in ablinded mode"

[0016] Patent number: US20230074617A1

[0017] Technical Overview: The patent provides a system for monitoring an analyte in a host, including a continuous analyte sensor that generates a data stream indicating the analyte concentration of the host, and a device that receives and records the data stream from the continuous analyte sensor. In one embodiment, the device includes a single-point analyte monitor from which the analyte value is obtained and is configured to display only the single-point analyte measurement value without displaying any analyte measurement value related to the data received from the continuous analyte sensor. Instead, the data received from the continuous analyte sensor is used to provide an alert to the user when the analyte concentration and / or the rate of change of the analyte concentration is above or below a preset range. In addition, the received data can also be used to prompt the diabetic patient or caregiver to take certain actions, such as taking another single-point blood glucose measurement.

[0018] In another embodiment, the device provides a switching function between two modes, one of which allows the display of the blood glucose concentration value associated with the continuous blood glucose sensor, while the second mode prevents the display of the blood glucose concentration value associated with the continuous blood glucose sensor. An optical sensor is introduced that uses near-infrared spectroscopy to detect blood glucose levels. The method has high sensitivity, but is affected by external light and skin thickness, resulting in unstable measurement accuracy.

[0019] (3) Patent name: "Analyte sensor"

[0020] Patent No.: US11382539B2

[0021] Technical Overview: This patent provides a system and method for continuously measuring analytes in the host's vascular system. In some embodiments, the continuous glucose measurement system includes a vascular access device, a sensor, and sensor electronics, and the system is configured to be inserted into a peripheral vein or artery of the host. A monitoring device for invasively detecting blood glucose is proposed. The device needs to be inserted into the skin and blood is collected through a vein or artery to measure the concentration. Although the device has a certain sensitivity, it is an invasive method, which limits its popular application and lacks sufficient structural optimization and portability design.

[0022] (4) Patent name: "Non-invasive blood glucose monitoring system"

[0023] Patent No.: US20050043603A1

[0024] Technical Overview: This patent is a non-invasive blood glucose monitoring system whose sensors contact different locations of the ear and are calibrated to ensure an accuracy of at least ±0.035 degrees Celsius. The sensor can continuously collect ear temperature up to four times per minute and calculate the temperature difference at these locations. Combined with the baseline blood glucose reference value determined by taking the square root of the product of fasting blood glucose and glycosylated hemoglobin (HbA1c), the change in temperature difference can be determined. If the temperature difference decreases, it means that blood glucose has increased by approximately 1 mg / dl for each decrease of approximately 0.024 degrees Celsius; if the temperature difference increases, it means that blood glucose has decreased by approximately 1 mg / dl for each increase of approximately 0.024 degrees Celsius. Summary of the invention

[0025] The purpose of the present invention is to solve the problem of low sensitivity of the existing non-invasive glucose sensor and to provide a substrate integrated waveguide microwave sensor for glucose detection.

[0026] The substrate integrated waveguide microwave sensor for glucose detection of the present invention comprises an input feeder, an integrated waveguide and a split ring resonator, wherein the integrated waveguide (SIW) is a fan-shaped microstrip line, a split ring resonator (SRR) is arranged in the middle of the fan-shaped microstrip line, the input feeder is located on the central axis of the integrated waveguide, one end (free end) of the input feeder is located outside the circular arc of the integrated waveguide, the other end of the input feeder extends into the interior of the integrated waveguide, and a metallized through hole array is arranged along the circumference of the circular arc of the integrated waveguide.

[0027] The present invention proposes a substrate integrated waveguide microwave sensor for glucose detection, which combines a substrate integrated waveguide (SIW) and a split ring resonator (SRR) structure, aiming to achieve high-sensitivity detection of glucose concentration by optimizing electromagnetic properties. The substrate integrated waveguide (SIW) structure in the substrate integrated waveguide microwave sensor adopts an improved quarter-mode SIW structure. Compared with the prior art, the structure is more compact and can achieve efficient electromagnetic wave propagation in a smaller space. The design of the split ring resonator (SRR) concentrates the electric field in the ring, and the electric field strength is greatly improved compared to the traditional design. This design helps to improve the sensitivity to changes in the dielectric constant of the liquid.

[0028] The substrate integrated waveguide microwave sensor for glucose detection of the present invention has the following beneficial effects:

[0029] 1. Integrated design: This invention combines the SIW structure with the SRR structure for glucose detection for the first time, achieving efficient space utilization and excellent electromagnetic properties, and significantly improving the performance and sensitivity of the sensor.

[0030] 2. High sensitivity and good linearity: The sensor exhibits excellent sensitivity and linear response in a wide concentration range (0-1000 mg / dL), meeting clinical testing requirements.

[0031] 3. Non-invasive detection: The sensor design makes it suitable for non-invasive monitoring, reducing interference to patients and improving the user experience.

[0032] 4. Electric field enhancement technology: By optimizing the SRR structure, the electric field strength is significantly improved and the sensitivity to changes in dielectric constant is enhanced.

[0033] 5. Multi-purpose application potential: In addition to blood glucose monitoring, the design and principle of this sensor can also be extended to other liquid detection fields, such as food safety monitoring and environmental testing, and has broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 The equivalent circuit diagram of the substrate integrated waveguide microwave sensor for glucose detection of the present invention;

[0035] Figure 2 It is a structural diagram of a substrate integrated waveguide microwave sensor for glucose detection of the present invention;

[0036] Figure 3 Graphs showing the electric field distribution of a substrate-integrated waveguide microwave sensor for glucose detection in an embodiment, (a) without a split ring resonator, (b) with a split ring resonator;

[0037] Figure 4 It is a S parameter simulation comparison diagram of the substrate integrated waveguide microwave sensor SIW structure and SIW-SRR structure in the embodiment;

[0038] Figure 5 Graphs showing the relationship between the reflection response and the frequency of the substrate integrated waveguide microwave sensor measured at different glucose concentrations in the embodiments, wherein (a) and (c) respectively show the variation of the reflection response with frequency at the low frequency point and the high frequency point of the tested glucose concentration, and (b) and (d) respectively reflect the variation trend of the reflection coefficient and the frequency at the low frequency point and the high frequency point as the glucose concentration changes. DETAILED DESCRIPTION

[0039] Specific implementation method one: The substrate integrated waveguide microwave sensor for glucose detection in this implementation method includes an input feed line 1, an integrated waveguide 2 and a split ring resonator 3. The integrated waveguide (SIW) 2 is a fan-shaped microstrip line, and a split ring resonator (SRR) 3 is arranged in the middle of the fan-shaped microstrip line. The input feed line 1 is located on the central axis of the integrated waveguide 2, one end (free end) of the input feed line 1 is located outside the arc of the integrated waveguide 2, and the other end of the input feed line 1 extends into the interior of the integrated waveguide 2. A metallized through-hole array 4 is arranged along the circumference of the arc of the integrated waveguide 2, so that the electromagnetic field transmission in the planar resonator has a waveguide property.

[0040] This embodiment combines substrate integrated waveguide (SIW) and split ring resonator (SRR) structures with efficient electromagnetic characteristics and fast response capabilities.

[0041] Specific implementation method 2: The difference between this implementation method and specific implementation method 1 is that the central angle of the fan-shaped microstrip line is 90°, and the radius R1 of the fan-shaped microstrip line is 34-38 mm.

[0042] Specific embodiment 3: This embodiment is different from specific embodiment 1 or 2 in that the radius R2 of the split ring resonator 3 is 7-8 mm.

[0043] Specific embodiment 4: This embodiment is different from any one of specific embodiments 1 to 3 in that the split ring resonator 3 is an annular gap c with an opening, and the width of the annular gap c is 1 mm.

[0044] Specific embodiment 5: This embodiment is different from specific embodiment 4 in that the opening of the split ring resonator 3 faces upward.

[0045] Specific implementation example 6: This implementation example is different from the specific implementation example 1 in that the width Wp of the input feeder line 1 is 3.5-4 mm, and the length of the feeder line segment Ls of the input feeder line 1 extending into the integrated waveguide 2 is 10-13 mm.

[0046] Specific embodiment 7: The difference between this embodiment and specific embodiment 6 is that the width of the gap Ws between the feeder section where the input feeder line 1 extends into the integrated waveguide 2 and the integrated waveguide 2 is 1 to 1.2 mm.

[0047] Specific embodiment eight: This embodiment is different from any one of specific embodiments one to seven in that a through hole array perturbation 4 is arranged along the arc circumference of the integrated waveguide 2, and the number of the through hole array perturbations 4 is 10 to 14.

[0048] Specific embodiment 9: The difference between this embodiment and specific embodiment 8 is that the aperture D of the through holes in the through hole array perturbation 4 is 0.8-1.2 mm.

[0049] Specific embodiment ten: The difference between this embodiment and specific embodiment eight is that the spacing P between adjacent through holes in the through hole array perturbation 4 is 3.5-4.0 mm.

[0050] Embodiment: The substrate integrated waveguide microwave sensor for glucose detection in this embodiment comprises an input feed line 1, an integrated waveguide 2 and a split ring resonator 3. The integrated waveguide (SIW) 2 is a fan-shaped microstrip line, the radius R1 of the fan-shaped microstrip line is 36 mm, the central angle of the fan-shaped microstrip line is 90° (quarter circle), a split ring resonator 3 is arranged in the middle of the fan-shaped microstrip line, the split ring resonator (SRR) 3 is an annular gap c with an upward opening, the (outer) radius R2 of the split ring resonator 3 is 7.5 mm, the width of the annular gap c is 1 mm, the width g of the opening is 0.3 mm, the input feed line 1 is located at the integrated waveguide 2, and the integrated waveguide 2 is located at the integrated waveguide 2. On the central axis of the integrated waveguide 2, the width Wp of the input feeder line 1 is 3.8 mm, one end (free end) of the input feeder line 1 is located outside the arc of the integrated waveguide 2, and the other end of the input feeder line 1 extends into the interior of the integrated waveguide 2, the length of the feeder segment Ls extending into the integrated waveguide 2 is 12 mm, and the gap width Ws between the feeder segment of the input feeder line 1 extending into the integrated waveguide 2 and the integrated waveguide 2 is 1 mm. A metallized through-hole array 4 is arranged along the circumference of the arc of the integrated waveguide 2, the number of through-hole arrays 4 is 12, the through-hole diameter D of the through-hole array perturbation 4 is 1 mm, and the spacing between adjacent through-holes in the through-hole array perturbation 4 is 3.8 mm.

[0051] The preparation process of the substrate integrated waveguide microwave sensor for glucose detection in this embodiment is as follows:

[0052] 1. Material selection: F4B255 double-sided copper clad laminate is used, which has good dielectric properties. The dielectric constant of this material is 2.52, the loss tangent is 0.0015, and the thickness is 0.5mm.

[0053] 2. Dimensions and parameters: Table I lists the detailed structural parameters of the substrate integrated waveguide microwave sensor, including the dimensions of each part, to ensure the best electromagnetic coupling effect.

[0054] Table I Sensor design parameters (unit: mm)

[0055]

[0056] Cleaning: Clean the surface of the board to remove oxides or contaminants to ensure that the light shielding layer can be well bonded to the copper surface during the subsequent etching process.

[0057] 3. Apply photoresist: Apply a layer of photoresist (positive or negative) on both sides of the board to create circuit patterns.

[0058] 4. UV exposure: The sensor design pattern is transferred to the plate through a photomask through UV exposure. The photomask contains the pattern required for etching, including the dimensions of R1, R2 and other feature positions.

[0059] 5. Development: After exposure, the board is developed to remove the unexposed (or exposed, depending on the type of photoresist) areas and reveal the copper layer to be etched.

[0060] 6. Copper etching: Place the board in an etching solution (such as ferric chloride solution) to remove the exposed copper area and form the sensor pattern. This step accurately etches the slots and unnecessary copper layers.

[0061] 7. Remove photoresist: After etching, remove the remaining photoresist and only retain the required copper circuits and sensor structures on the board.

[0062] 8. Drilling: According to the size requirements of D and P in the design drawing, use CNC machine tools to accurately drill through holes or blind holes.

[0063] 9. Apply solder mask: In order to protect the copper circuit, apply solder mask and only expose the connection points.

[0064] 10. Quality Control: Check the finished products to ensure that the size and specifications are consistent with the design and there are no defects.

[0065] 11. Functional test: Perform basic functional tests on the sensor to verify the integrity of the copper circuit and ensure that the sensor design can meet the working requirements.

[0066] Through experiments, the substrate integrated waveguide microwave sensor showed excellent sensitivity and accuracy in the detection of glucose solutions with different concentrations. The specific experimental steps are as follows:

[0067] a. Use glucose powder and deionized water to prepare glucose solutions of different concentrations (0 mg / dL, 200 mg / dL, 400 mg / dL, 600 mg / dL, 800 mg / dL, 1000 mg / dL).

[0068] b. Connect SubMiniature version A (SMA) to vector network analyzer (VNA), place the prepared glucose solutions of different concentrations into the container on the sensor in sequence through a dropper, and record the reflected signal.

[0069] c. Through data analysis, the sensitivity of the sensor was found to be 0.014 MHz / (mg / dL), and it was found that it showed a good linear fit in the range of 200-1000 mg / dL. Figure 5 (a) shows the response curve of the sensor to the change of glucose solution concentration at low frequency. Figure 5 (b) shows the response of the sensor operating frequency and amplitude to changes in glucose concentration at low frequencies, respectively, with good linearity from 0 to 1000 mg / dL. Figure 5 (c) shows the response curve of the sensor to the change of glucose solution concentration at high frequency. Figure 5 (d) The responses of the sensor's operating frequency and amplitude to changes in glucose concentration at high frequencies are shown. The sensor has good linearity at 200-1000 mg / dL, and the amplitude of change is larger than that at low frequencies. Combining the changes in the operating frequency and amplitude of the two, good real-time monitoring of glucose solutions of 0-1000 mg / dL can be achieved, providing a convenient detection method for diabetic patients.

[0070] Experimental results show that the sensor can monitor changes in glucose concentration in real time, providing a convenient detection method for diabetic patients.

[0071] 1. Improved sensitivity: Through the optimized combination of SIW and SRR structures, the sensor has a sensitivity of 0.014MHz / (mg / dL) in the glucose concentration range of 0-1000mg / dL, and performs particularly well in low-concentration detection.

[0072] 2. Fast response: This sensor can achieve real-time detection, thanks to its compact design and efficient electromagnetic field coupling. Compared with traditional methods, the detection cycle is significantly shortened.

[0073] 3. Non-invasive monitoring capability: Due to its design principle, the sensor can be applied to non-invasive blood glucose monitoring, providing users with a more convenient detection solution.

Claims

1. A substrate-integrated waveguide microwave sensor for glucose detection, characterized in that The substrate integrated waveguide microwave sensor comprises an input feed line (1), an integrated waveguide (2) and a split ring resonator (3); the integrated waveguide (2) is a fan-shaped microstrip line, the split ring resonator (3) is arranged in the middle of the fan-shaped microstrip line, the input feed line (1) is located on the central axis of the integrated waveguide (2), one end of the input feed line (1) is located outside the circular arc of the integrated waveguide (2), the other end of the input feed line (1) extends into the interior of the integrated waveguide (2), and a metallized through hole array (4) is arranged along the circumference of the circular arc of the integrated waveguide (2).

2. The substrate integrated waveguide microwave sensor for glucose detection according to claim 1, characterized in that The central angle of the fan-shaped microstrip line is 90°, and the radius (R1) of the fan-shaped microstrip line is 34 to 38 mm.

3. The substrate integrated waveguide microwave sensor for glucose detection according to claim 1, characterized in that The radius (R2) of the split ring resonator (3) is 7 to 8 mm.

4. The substrate integrated waveguide microwave sensor for glucose detection according to claim 1, characterized in that The split ring resonator (3) is an annular gap (c) with an opening, and the width of the annular gap (c) is 1 mm.

5. The substrate integrated waveguide microwave sensor for glucose detection according to claim 4, characterized in that The opening of the split ring resonator (3) faces upward.

6. The substrate integrated waveguide microwave sensor for glucose detection according to claim 1, characterized in that The width (Wp) of the input feeder line (1) is 3.5-4 mm, and the length of the feeder line section (Ls) of the input feeder line (1) extending into the integrated waveguide (2) is 10-13 mm.

7. The substrate integrated waveguide microwave sensor for glucose detection according to claim 6, characterized in that The width of the gap (Ws) between the feeder section of the input feeder (1) extending into the integrated waveguide (2) and the integrated waveguide (2) is 1 to 1.2 mm.

8. The substrate integrated waveguide microwave sensor for glucose detection according to claim 1, characterized in that A through hole array perturbation (4) is arranged along the arc circumference of the integrated waveguide (2), and the number of the through hole array perturbations (4) is 10 to 14.

9. The substrate integrated waveguide microwave sensor for glucose detection according to claim 8, characterized in that The aperture (D) of the through holes in the through hole array perturbation (4) is 0.8 to 1.2 mm.

10. The substrate integrated waveguide microwave sensor for glucose detection according to claim 8, characterized in that The spacing (P) between adjacent through holes in the through hole array perturbation (4) is 3.5-4.0 mm.

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