Active fano resonance blood glucose sensor

Abstract

An active Fano resonance blood glucose sensor, relating to the field of non-invasive blood glucose monitoring. The blood glucose sensor comprises a resonator, an excitation layer, a low-noise amplifier (8) and a phase shifter (9), wherein the resonator, the low-noise amplifier (8) and the phase shifter (9) form a connection loop; the resonator is provided on the excitation layer; and the excitation layer is connected to an external excitation source. By using the phase shifter (9), the phase of an active circuit can be changed to selectively enhance resonance, improve the resonance Q factor, and realize detection of minor changes in blood glucose concentration, and thus the active Fano resonance blood glucose sensor can be applied to human blood glucose sensing and the problems in the prior art of poor stability and robustness. Moreover, by using the resonator and the excitation layer, self-reference error elimination can be achieved, significantly improving the performance of the microwave blood glucose sensor and improving the reliability of blood glucose measurement.

Description

An active Fano resonance blood glucose sensor

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on February 20, 2024, with application number 2024101880534 and invention name “A blood glucose sensor with active Fano resonance”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present invention relates to the field of non-invasive blood glucose monitoring, and in particular to an active Fano resonance blood glucose sensor. Background Art

[0003] Diabetes is one of the most prevalent chronic diseases worldwide. Effective blood glucose management can significantly improve patient outcomes and reduce complications. Currently, the main methods for blood glucose monitoring include traditional fingertip blood glucose meters (BGMs) and continuous glucose monitoring (CGMs). BGMs typically collect blood from the fingertip, which is relatively accurate, but carries a certain degree of pain and infection risk. Single-point blood glucose values ​​measured by BGMs cannot accurately reflect blood glucose trends, creating a blind spot during nighttime, which can easily miss hypoglycemia and hyperglycemia peaks. This prevents continuous blood glucose monitoring, which can help detect abnormal blood glucose levels in a timely manner. CGMs use subcutaneous sensors to measure interstitial fluid glucose concentrations. Based on the correlation between interstitial fluid glucose and blood glucose concentrations, algorithms are used to convert these concentrations into blood glucose readings. This allows for 24-hour continuous monitoring and near-real-time display of blood glucose trends. However, CGMs' indirect measurement requires an algorithm to convert interstitial fluid glucose levels into real-time blood glucose levels, resulting in measurement delays and a relatively high price. Non-invasive continuous blood glucose monitoring devices offer an effective solution, but current photoelectric and microwave-based non-invasive blood glucose monitoring systems suffer from insufficient measurement accuracy. Therefore, there is an urgent need to develop low-cost, high-precision, non-invasive continuous blood glucose monitoring equipment, and low-cost, extremely high sensitivity, non-invasive microwave sensors are the most critical part.

[0004] Microwave blood glucose sensors are a non-invasive sensing technology that monitors blood glucose levels by measuring the dielectric properties of glucose molecules in the blood. Microwave blood glucose sensors have the advantages of being non-invasive, real-time, and portable, and therefore have become a new research hotspot. The dielectric constant of a substance has a specific relationship with frequency, and microwave blood glucose sensors infer the physical properties of the substance by measuring the dielectric constant. Traditional microwave sensors utilize near-field coupling between the substance being measured and a sensor based on a microwave resonator. Changes in the resonant position and amplitude are used to determine changes in the dielectric constant, and thus changes in certain properties of the substance. However, planar microwave circuit structures often exhibit radiation losses, which reduces the quality factor (Q) of microwave-based blood glucose sensors. This is especially true when the substance being measured often exhibits significant losses, further accelerating the degradation of the quality factor (Q).

[0005] Microwave blood glucose sensors based on artificial localized surface plasmons (ALSPs) have the potential to offer superior performance. However, the structural losses of passive structures limit sensor accuracy. To compensate for these losses and further improve measurement accuracy (minimum detectable resolution), active circuitry can be added. Active ALSP sensors combined with active amplification circuits can compensate for these losses and successfully increase the Q factor by several orders of magnitude. Fano resonance can further effectively suppress radiation losses, and active Fano resonance sensors can achieve measurement accuracies of 10 mg / dL. However, these sensors still face stability and robustness issues, hindering their application in human blood glucose sensing.

[0006] Summary of the Invention

[0007] In order to solve the above problems existing in the prior art, the present invention provides an active Fano resonance blood glucose sensor.

[0008] To achieve the above object, the present invention provides the following solutions:

[0009] An active Fano resonance blood glucose sensor comprises: a resonator, an excitation layer, a low noise amplifier and a phase shifter;

[0010] The resonator, the low noise amplifier and the phase shifter form a connection loop; the resonator is arranged on the excitation layer; the excitation layer is connected to an external excitation source;

[0011] The resonator is used to generate a resonant mode; the low-noise amplifier is used to amplify and couple the Fano resonant signal after the phase shifting process of the phase shifter, and output it to the resonator.

[0012] Optionally, the resonator includes a first dielectric substrate;

[0013] Etching on the first dielectric base layer to obtain a first metal grating structure layer, a second metal grating structure layer and a metal coupling patch;

[0014] The metal coupling patch is coupled with the second metal grating structure layer; the second metal grating structure layer is coupled with the first metal grating structure layer; the metal coupling patch, the low noise amplifier and the phase shifter are connected to form a loop.

[0015] Optionally, the excitation layer includes: a microstrip line, a second dielectric base layer and a metal backplane layer;

[0016] The second dielectric base layer is arranged between the first dielectric base layer and the metal backplane layer; the microstrip line is arranged between the first dielectric base layer and the second dielectric base layer; and the microstrip line is connected to the external excitation source.

[0017] Optionally, the first dielectric base layer and the second dielectric base layer are both made of Rogers RO4350B high-frequency board.

[0018] Optionally, the relative dielectric constant of the Rogers RO4350B high-frequency board is 3.48, and the loss tangent is 0.004; the substrate thickness of the Rogers RO4350B high-frequency board is 1.016 mm, and the metal layer thickness of the Rogers RO4350B high-frequency board is 0.035 mm.

[0019] Optionally, the low noise amplifier and the phase shifter are connected to the metal coupling patch via a radio frequency connection line.

[0020] Optionally, a central extension line of the microstrip line is perpendicular or parallel to a central extension line of the opening of the metal coupling patch.

[0021] Optionally, the low noise amplifier is a low noise amplifier chip of model TRF37C75IDSGR.

[0022] Optionally, the phase shifter is a six-bit digital phase shifter chip of model HMC649ALP6E.

[0023] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0024] The present invention utilizes a phase shifter to alter the phase of the active circuit, selectively enhancing Fano resonance and increasing its Q value. This allows detection of minute changes in blood glucose concentration, enabling its application in human blood glucose sensing and resolving stability and robustness issues associated with existing technologies. Furthermore, the use of a resonator and excitation layer eliminates self-reference errors, significantly improving the performance of microwave blood glucose sensors and enhancing the reliability of blood glucose detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] FIG1 is a schematic structural diagram of an active Fano resonance blood glucose sensor provided by the present invention;

[0027] FIG2 is a schematic structural diagram of another active Fano resonance blood glucose sensor provided by the present invention;

[0028] FIG3 is a top view of the second dielectric substrate provided by the present invention;

[0029] FIG4 is a structural diagram of an active Fano resonant blood glucose sensor provided by the present invention;

[0030] FIG5 is a comparison diagram of the transmission coefficients of the active Fano resonant blood glucose sensor provided by the present invention and the passive grooved metal plate without active circuit loading;

[0031] FIG6 is a comparison diagram of experimental results of the active Fano resonant blood glucose sensor provided by the present invention and a blood sampling type blood glucose meter;

[0032] FIG7 is a diagram showing the transmission coefficient S when passive and active dual Fano resonators compensate M1 under actual measurement conditions of the present invention. 21 Comparison chart of

[0033] FIG8 is a graph showing the transmission coefficient S when the passive and active dual Fano resonators compensate for M2 under actual measurement conditions of the present invention. 21 Comparison chart.

[0034] Explanation of symbols:

[0035] First dielectric base layer—1, second metal grating structure layer—2, metal coupling patch—3, first metal grating structure layer—4, microstrip line metal excitation layer—5, second dielectric base layer—6, metal backplane layer—7, low noise amplifier—8, phase shifter—9. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] The purpose of the present invention is to provide an active Fano resonance blood glucose sensor, which can detect tiny changes in blood glucose concentration while achieving an improvement in Fano resonance intensity and Q value, thereby solving the stability and robustness problems existing in the prior art. In addition, it can be conveniently applied to human blood glucose sensing, greatly improving the performance of microwave blood glucose sensors.

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Compared with a single Fano resonance, a dual-path Fano resonance can realize a self-reference function, further reducing experimental errors. Usually, a passive resonator needs to have a corresponding active circuit for enhancement. If it involves realizing multiple active resonances at the same time, it is necessary to design multiple active circuits to match the corresponding multiple passive resonators respectively. This will inevitably complicate the structure of the active sensor, and in order to integrate multiple active circuits, the size of the device must be increased, which will increase the size of the entire sensor. In order to solve these problems, the present invention only uses one active circuit, and by changing the phase of the active circuit through a phase shifter, the two Fano resonances can be selectively enhanced. The Q values ​​of the two resonances can reach 52002 and 46713 respectively after enhancement, and both can be used to detect small changes in blood glucose concentration (for example, they can be used to detect small changes in blood glucose concentration of 5 mg / dL). The average sensitivity of the dual resonance in glucose solution concentration detection can reach 3.07kHz / (mg·dL -1 ) and 2.6kHz / (mg·dL -1 The sensor design, which utilizes a dual-path Fano resonant structure, achieves self-reference error cancellation. This normalizes the outputs of a set of sensors so that both sensors experience the same influences in the same environment. This self-reference mechanism effectively eliminates errors, making the sensor more reliable in complex environments.

[0040] Example 1

[0041] The active Fano resonance blood glucose sensor provided in this embodiment is a single-channel injection-locked oscillation active Fano resonance blood glucose sensor, as shown in FIG1 and FIG4 , which includes: a resonator, an excitation layer, a low-noise amplifier 8 and a phase shifter 9.

[0042] The resonator, low noise amplifier 8 and phase shifter 9 form a connection loop. The resonator is arranged on the excitation layer. The excitation layer is connected to an external excitation source.

[0043] The resonator is used to generate a Fano resonance mode. The low noise amplifier 8 is used to amplify and couple the Fano resonance signal after the phase shift processing by the phase shifter 9, and then output it to the resonator.

[0044] The resonator includes a first dielectric substrate 1. A first metal grating structure layer 4, a second metal grating structure layer 2 and a metal coupling patch 3 are etched on the first dielectric substrate 1 to form the upper half of the blood glucose sensor.

[0045] The metal coupling patch 3 is coupled to the second metal grating structure layer 2. The second metal grating structure layer 2 is coupled to the first metal grating structure layer 4. The metal coupling patch 3, low-noise amplifier 8, and phase shifter 9 are connected to form a loop. Specifically, as shown in Figure 1, the first metal grating structure is located inside the second metal grating, the first metal grating and the second metal grating intersect, and the metal coupling patch 3 is located outside the second metal grating.

[0046] Furthermore, the low-noise amplifier 8 and the phase shifter 9 form an external active circuit of the blood glucose sensor. In actual application, an active part based on the injection-locked oscillation technology is introduced through the metal coupling branch (i.e., the metal coupling patch 3), and the phase shift angle of the metal coupling branch and the phase shifter 9 is adjusted so that the phase meets the oscillation condition. For example, the low-noise amplifier 8 module can use the low-noise amplifier 8 chip of Texas Instruments, model TRF37C75IDSGR, which has a gain of 16dB. The phase shifter 9 module can use the six-bit digital phase shifter 9 chip of Analog Devices, Inc., model HMC649ALP6E, which has a minimum phase shift angle of 5.625°. Based on this, the metal coupling patch 3 can be connected to an external active circuit to couple the external active amplified signal to the first metal grating structure layer 4.

[0047] Furthermore, the low noise amplifier 8 and the phase shifter 9 can be connected to the metal coupling patch 3 through a radio frequency connection line or an adapter to introduce an active part based on injection locked oscillation technology, thereby enhancing the strength of Fano resonance, reducing the resonance linewidth, and improving the sensitivity of the system.

[0048] Furthermore, the excitation layer includes: a microstrip line, a second dielectric base layer 6 and a metal backplane layer 7 .

[0049] The second dielectric base layer 6 is disposed between the first dielectric base layer 1 and the metal backplane layer 7. A microstrip line is disposed between the first dielectric base layer 1 and the second dielectric base layer 6. The microstrip line is connected to an external excitation source. The second dielectric layer is shown in FIG3 .

[0050] Furthermore, the central extension of the microstrip line is arranged parallel to the central extension of the opening of the metal coupling patch 3. The microstrip line is essentially a microstrip metal excitation layer 5, which is a microstrip line feeding structure and forms the upper half of the Fano resonator with the first metal grating structure.

[0051] Furthermore, the first metal grating structure layer 4 and the second metal grating structure layer 2 form the core of the resonator to form the structure of the Fano resonator. The first metal grating structure layer 4 and the second metal grating structure layer 2 are connected to the first dielectric substrate 1 and the microstrip line feeding structure to form the passive structure of the active Fano resonant sensor.

[0052] The primary function of the first dielectric substrate 1 and the second dielectric substrate 6 is to provide basic support and ensure the structural stability of the blood glucose sensor. Both dielectric substrates are made of Rogers RO4350B high-frequency board. The relative dielectric constant of the Rogers RO4350B high-frequency board is 3.48, and the loss tangent is 0.004. The substrate thickness of the Rogers RO4350B high-frequency board is 1.016mm, and the metal layer thickness of the Rogers RO4350B high-frequency board is 0.035mm.

[0053] Example 2

[0054] The active Fano resonance blood glucose sensor provided in this embodiment is a dual-channel injection-locked oscillation active Fano resonance blood glucose sensor, as shown in Figure 2. The components used are the same as the components used in the above-mentioned embodiment 1. The structural difference from the blood glucose sensor provided in embodiment 1 is that the active circuit part in this embodiment is obtained by rotating the active circuit part of embodiment 1 by 90°, that is, the first dielectric base layer 1 of the blood glucose sensor is rotated 90° clockwise. Specifically, the center extension line of the microstrip line is perpendicular to the center extension line at the opening of the metal coupling patch 3 to generate dual Fano resonance. By changing the phase of the active circuit through the phase shifter 9, the two Fano resonances can be selectively enhanced.

[0055] Furthermore, Figure 5 compares the transmission coefficients of the active Fano resonant blood glucose sensor introduced by the present invention and a passive sensor without active circuitry. For the passive Fano resonant mode, the measured Q value is 51 and the resonance intensity is 19dB. However, for the active Fano resonant blood glucose sensor, the resonant mode is locked within a very small range due to weak injection, significantly improving both the Q value and resonance intensity. The measured Q value is 115397 and the resonance intensity is 68dB. This shows that the present invention has good resonant characteristics and can achieve the effect of active gain compensation.

[0056] Figure 6 compares the experimental results of the active Fano resonant blood glucose sensor provided by the present invention and a blood sampling blood glucose meter. This experiment primarily measured changes in blood glucose concentration within one hour after a meal. The horizontal axis represents time in minutes, the left vertical axis represents the frequency corresponding to the peak value in GHz, and the right vertical axis represents the blood glucose level. The experimental results were obtained by collecting fingertip blood using a blood glucose meter in mmol / L.

[0057] FIG7 is a diagram showing the transmission coefficient S when passive and active dual Fano resonators compensate M1 under actual measurement conditions of the present invention. 21 By adjusting phase shifter 9 to keep the self-oscillating signal in the M1 mode, a low-power signal is injected, locking the input signal within a narrow frequency range and compensating for the M1 mode. For the passive Fano resonant mode, the measured Q value is 14, and the resonance intensity is 15.5 dB. However, for the active Fano resonant blood glucose sensor, the resonant mode is locked within a narrow range due to weak injection, significantly improving the Q value and resonance intensity. The measured Q value is 52002, and the resonance intensity is 93.95 dB.

[0058] FIG8 is a graph showing the transmission coefficient S when the passive and active dual Fano resonators compensate for M2 under actual measurement conditions of the present invention. 21 By adjusting the phase shifter 9 to change the phase of the active loop, when the phase meets the starting condition, the self-excited oscillation signal oscillates at the frequency of the M2 mode, so that the Fano resonance in the M2 mode is accurately compensated. For the passive Fano resonance mode, the measured Q value is 51 and the resonance intensity is 23.7dB, while for the active Fano resonant blood glucose sensor, the measured Q value is 46713 and the resonance intensity is 96.61dB. In Figures 7 and 8, Frequency represents frequency, Passive represents passive, and Active (M * ) indicates active compensation M1 or M2.

[0059] In order to improve the integration of the entire active sensor, the specific structure of the active Fano resonant blood glucose sensor provided in the present invention can be processed using PCB technology, and can also be processed using different processing technologies according to different operating frequency bands.

[0060] Based on the above description, the blood glucose sensor provided by the present invention introduces an active circuit to compensate for structural losses. The active part uses injection-locked oscillation technology. By changing the phase of the active circuit, selective and precise enhancement of Fano resonance can be achieved. In the sensing test of glucose solution, it can be used to detect small changes in glucose concentration of 10mg / dL. The average sensitivity of the dual-path resonance in glucose solution concentration detection can reach 6.25kHz / (mg·dL -1 ), this structure is expected to be used in high-resolution blood glucose concentration sensing and other biochemical sensing applications.

[0061] The present invention realizes an active Fano resonant blood glucose sensor based on injection-locked oscillation, which can be applied to non-invasive blood glucose monitoring technology, improves the detection sensitivity and resolution of microwave sensors, is suitable for blood glucose monitoring of diabetic patients, thereby improving the quality of life of patients and reducing medical expenses, and is also suitable for healthy people for self-blood glucose monitoring.

[0062] Compared with the prior art, the present invention also has the following advantages:

[0063] 1) This invention can improve the Q value and resonance strength of the resonator, thereby enhancing resolution and sensitivity. The active portion utilizes injection-locked oscillation technology, which locks the oscillating signal within a very small range through weak injection. By adjusting the phase, precise loss compensation can be achieved, which increases signal strength and makes the sensor more stable during signal measurement. Alternatively, by selectively enhancing the two passive resonators, the Q value and resonance strength are significantly increased. This feature increases the sensor's sensitivity to tiny signal changes, thereby improving its resolution.

[0064] 2) The present invention features miniaturization and integration: The passive structure utilizes a planar microwave resonator based on an artificial localized surface plasmon structure. The coupling of two artificial localized surface plasmon structures produces a Fano resonance (or dual Fano resonance) effect, reducing the size of the device and facilitating its wearable design for human blood glucose monitoring. This integrated design effectively reduces the sensor's structural complexity and manufacturing cost, making the product more economical and practical.

[0065] 3) High measurement stability: The present invention utilizes a two-layer design, consisting of an upper artificial surface plasmon resonator and a lower coupled microstrip feed structure. This layered structure facilitates better control of sensor performance, and the metal ground shields external electromagnetic interference, contributing to measurement stability.

[0066] 4) The present invention can be applied to non-invasive blood glucose monitoring: The blood glucose sensor has greatly improved the detection performance of concentration changes in high-loss media, making it very suitable for wearable non-invasive blood glucose monitoring.

[0067] In general, the active Fano resonant sensor based on injection-locked oscillation provided by the present invention exhibits higher accuracy and better resolution in the field of blood glucose sensing compared to traditional passive and active microwave sensors, providing a more advanced solution.

[0068] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0069] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. An active Fano resonance blood glucose sensor, characterized in that: include: resonators, excitation layers, low-noise amplifiers, and phase shifters; The resonator, the low noise amplifier and the phase shifter form a connection loop; The resonator is arranged on the excitation layer; The excitation layer is connected to an external excitation source; The resonator is used to generate a resonant mode; The low noise amplifier is used to amplify and couple the Fano signal after the phase shifting process of the phase shifter, and then output it to the resonator.

2. The active Fano resonance blood glucose sensor according to claim 1, characterized in that: The resonator includes a first dielectric substrate; Etching on the first dielectric base layer to obtain a first metal grating structure layer, a second metal grating structure layer and a metal coupling patch; The metal coupling patch is coupled with the second metal grating structure layer; the second metal grating structure layer is coupled with the first metal grating structure layer; the metal coupling patch, the low noise amplifier and the phase shifter are connected to form a loop.

3. The active Fano resonance blood glucose sensor according to claim 2, characterized in that: The excitation layer includes: a microstrip line, a second dielectric base layer and a metal backplane layer; The second dielectric base layer is arranged between the first dielectric base layer and the metal backplane layer; the microstrip line is arranged between the first dielectric base layer and the second dielectric base layer; and the microstrip line is connected to the external excitation source.

4. The active Fano resonance blood glucose sensor according to claim 3, characterized in that: The first dielectric base layer and the second dielectric base layer are both made of Rogers RO4350B high-frequency board.

5. The active Fano resonance blood glucose sensor according to claim 4, characterized in that: The relative dielectric constant of the Rogers RO4350B high-frequency board is 3.48, and the loss tangent is 0.004; the substrate thickness of the Rogers RO4350B high-frequency board is 1.016 mm, and the metal layer thickness of the Rogers RO4350B high-frequency board is 0.035 mm.

6. The active Fano resonance blood glucose sensor according to claim 2, characterized in that: The low noise amplifier and the phase shifter are connected to the metal coupling patch via radio frequency connection lines.

7. The active Fano resonance blood glucose sensor according to claim 3, characterized in that: The central extension line of the microstrip line is perpendicular or parallel to the central extension line of the opening of the metal coupling patch.

8. The active Fano resonance blood glucose sensor according to claim 1, characterized in that: The low noise amplifier is a low noise amplifier chip of model TRF37C75IDSGR.

9. The active Fano resonance blood glucose sensor according to claim 1, characterized in that: The phase shifter is a six-bit digital phase shifter chip of model HMC649ALP6E.

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