Wearable blood glucose continuous monitoring system based on two-dimensional area array ultrasound gating array

Abstract

The application discloses a wearable blood glucose continuous monitoring system based on a two-dimensional surface array ultrasonic gating array, which comprises a mobile terminal module, a communication module, a control and data processing module, a transmitting and receiving circuit, a gating array switch, a power module, an ultrasonic probe, a microneedle patch and a wearable ultrasonic module. On one hand, the TOF difference value of the needle tip echo and the reference echo is used to realize the reading of the length change of the non-optical microneedle, and the defect that the optical detection is easy to be disturbed is avoided; on the other hand, the local TOF data with spatial index is obtained by grouping and gating, and after statistical processing such as averaging, weighted averaging and outlier rejection, the ΔLavg is obtained, the multi-region parallel measurement is realized, the influence of single-point abnormality is reduced, the stability and reliability of continuous monitoring are significantly improved, and meanwhile, the flexible substrate not only provides mechanical support for the microneedle to pierce the skin, but also adapts to the surface curvature deformation, and avoids the inclination of the microneedle during scanning.

Description

Technical Field

[0001] This invention belongs to the field of medical device or biomedical engineering technology, specifically relating to a wearable continuous blood glucose monitoring system based on a two-dimensional area array ultrasonic gating array. Background Technology

[0002] Continuous analyte monitoring is a crucial area in wearable healthcare and chronic disease management. Taking blood glucose monitoring as an example, in clinical and home settings, it is often necessary to continuously obtain concentration trends under different conditions such as before meals, after meals, exercise, and sleep to facilitate medication, dietary, and risk warnings. However, existing continuous monitoring technologies mostly rely on electrochemical enzyme sensors, optical detection, or microfluidic sampling. While these methods have a certain application foundation, they can still be affected by factors such as enzyme stability, optical path stability, interference from sweat or tissue fluid components, sensor drift, and replacement frequency. Microneedle patches can penetrate the stratum corneum or superficial epidermis and contact interstitial fluid (ISF), obtaining information related to metabolic status in vivo under relatively low- or minimal-invasive conditions. Functionalized hydrogel microneedles, responsive polymer microneedles, or composite material microneedles can undergo volume expansion, length changes, refractive index changes, color changes, electrical changes, or mass changes in response to changes in the concentration of the target analyte. Therefore, microneedle patches provide a detection path for continuous analyte monitoring that differs from traditional enzyme electrodes.

[0003] For responsive hydrogel microneedles, changes in analyte concentration are typically manifested as changes in the overall expansion of the microneedle, the tip position, or the length of the needle. If the length change of the microneedle array can be detected in real time after the microneedles are inserted into the tissue, a mapping relationship can be established between this length change and the target analyte concentration, enabling continuous monitoring. Ultrasonic time-of-flight (TOF) ranging methods have advantages such as being non-optical, penetrating shallow tissues, and being able to be integrated with wearable hardware, and are theoretically suitable for detecting spatial position changes of the microneedle tip, microneedle substrate, or acoustic enhancement interface.

[0004] Traditional single-point ultrasound Time-of-Flight (TOF) measurements typically measure distances along only one acoustic beam path or within a localized area. For microneedle patches, the expansion changes of a single microneedle or a small number of microneedles are easily affected by microneedle fabrication errors, local skin pressure, uneven patch adhesion, differences in interstitial fluid distribution, uneven acoustic coupling, and user movement. Since microneedle patches are usually two-dimensional array structures, measuring changes at only a single location may not represent the average response of the entire patch. Meanwhile, two-dimensional area array ultrasound probes, composed of multiple array elements arranged in a two-dimensional matrix, can electronically select different elements or subarrays for transmission and reception. By spatially corresponding the two-dimensional area array probe with the microneedle array and sequentially acquiring TOF data from different regions through element gating, the length changes of multiple microneedles or microneedle subregions can be obtained. Averaging or weighted averaging these local results can significantly reduce the impact of local outliers and single-point errors on the final monitoring results.

[0005] Existing continuous analyte monitoring products mainly include electrochemical continuous glucose monitoring systems, sweat or tissue fluid biochemical sensor patches, optical sensor patches, and microneedle-assisted sampling or detection devices. Electrochemical continuous glucose monitoring typically uses subcutaneous or semi-implantable sensors to detect glucose concentration in interstitial fluid in real time and displays trends via an external transmitter or mobile terminal. While this type of product is relatively mature, its detection mechanism relies on enzyme reactions, electrode interfaces, and electrochemical readout. Long-term stability, sensor drift, calibration requirements, and biocompatibility remain issues that need attention. Among microneedle patch methods, common approaches include sampling microneedles, reactive microneedles, fluorescent or colorimetric microneedles, electrochemical microneedle electrodes, and hydrogel-responsive microneedles. Sampling microneedles typically introduce interstitial fluid into an external detection area; optical microneedles require color, fluorescence, or spectral signal readout; electrochemical microneedles require integrated electrodes and conductive pathways within the microneedle or patch; and hydrogel-responsive microneedles reflect analyte concentration through changes in volume or length. While each of the above solutions has its own advantages, they still have limitations to varying degrees in terms of long-term wearability, real-time readout, resistance to environmental interference, and wearable integration.

[0006] For measuring changes in the length of hydrogel microneedles, traditional laboratory methods include microscopic observation, image processing, weight change, in vitro expansion rate measurement, or optical readout methods. These methods are usually suitable for in vitro validation or short-term experiments, but are not convenient for continuous real-time detection after the microneedles are inserted into the skin. Especially when the microneedles are located between the patch and the skin, and the needle tip enters the interstitial fluid area, it is difficult for ordinary optical systems to directly observe changes in needle tip depth and length.

[0007] Ultrasonic ranging methods utilize the time-of-flight (TOF) of sound waves to calculate distance by emitting short-pulse ultrasound and receiving the interface echo. If the microneedle tip is equipped with acoustically enhanced microparticles, interfaces with acoustic impedance differences, or reflective structures, the TOF difference between the tip echo and the base reference echo can be used to calculate the effective length of the microneedle or the tip position. Compared to optical methods, ultrasonic measurement does not rely on a visible light path, allowing it to operate in patch-covered or shallow tissue environments, making it more suitable for wearable closed structures. However, when measuring microneedle changes with a single ultrasonic transducer or a single sound beam path, representativeness issues can easily arise. Different microneedles in a microneedle patch may exhibit different expansion amounts due to variations in manufacturing tolerances, local cross-linking levels, interstitial fluid absorption rates, and local mechanical pressure. If the system only reads TOF data from one location, local anomalies may be mistaken for overall concentration changes, leading to fluctuations in the monitoring curve or amplified errors. While linear array ultrasound probes or ordinary area array probes can be used for tissue imaging, their primary application is obtaining B-mode or 3D images, rather than performing element-gated TOF ranging on microneedle arrays. Existing wearable ultrasound patches are mostly used for monitoring blood flow, muscles, cardiovascular system or tissue structure, and usually focus on tissue echo images, blood flow velocity or tissue movement, rather than specifically measuring the average length change of multiple microneedles in the microneedle patch.

[0008] Therefore, the industry still lacks a solution that integrates microneedle arrays, two-dimensional area array ultrasonic probes, array element gating circuits, TOF difference calculation, and average change in a single wearable system. Such systems need to simultaneously address issues such as the spatial correspondence between the probe and the microneedle array, array element gating timing control, local TOF extraction, multi-region data fusion, motion interference suppression, concentration calibration, and continuous display on the mobile device. Overall, while existing microneedle patch continuous monitoring and ultrasonic ranging technologies each have a certain foundation, there are still significant problems when combining them for wearable continuous analyte monitoring, specifically as follows: 1. The length changes of existing hydrogel microneedles are usually difficult to read in real time while worn on the skin. That is, after the hydrogel microneedles enter the interstitial fluid, their tip position and degree of expansion are obscured by the patch, skin and tissue. Traditional microscopes or optical imaging methods are difficult to observe continuously while worn. If the patch must be removed for measurement, it will not only disrupt the continuous monitoring process, but also change the state of the microneedles and the tissue environment.

[0009] 2. Existing single-point TOF measurement results are not representative enough and are easily affected by local errors. That is, microneedle patches are usually composed of multiple microneedles, and the expansion rate and length change of different microneedles may vary. When a single sound beam measures a local location, local contact pressure, microneedle breakage, air bubbles, poor coupling, or uneven distribution of tissue fluid will significantly affect the results.

[0010] 3. Existing microneedle patches lack spatial correspondence and arrayed readout structures between the ultrasound module and the microneedle patch. That is, although ordinary ultrasound probes can transmit and receive ultrasound signals, they may not correspond to the arrangement, spacing and measurement area of ​​the microneedle array, which can easily lead to uncertain sound beam coverage, mixed echo sources and repeated measurements in local areas.

[0011] 4. Existing wearable monitoring systems are not robust enough to motion, adhesion pressure and coupling changes. That is, during daily wear, users may experience arm movements, skin deformation, slight slippage of the patch or changes in the thickness of the coupling layer. If the system only uses absolute TOF or a single echo peak, drift is likely to occur. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide an improved wearable continuous blood glucose monitoring system based on a two-dimensional area array ultrasonic gating array.

[0013] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A wearable continuous blood glucose monitoring system based on a two-dimensional ultrasonic gating array includes a mobile terminal module, a communication module, a control and data processing module, a transmitting and receiving circuit, a gating array switch, a power supply module, an ultrasonic probe, a microneedle patch, and a wearable ultrasonic module. The ultrasonic probe comprises multiple array elements arranged in a two-dimensional matrix. The microneedle patch includes a flexible substrate, a hydrogel microneedle array, and acoustic enhancement microparticles. The hydrogel microneedle array is arranged in a two-dimensional array based on the area covered by the ultrasonic probe and includes hydrogel monomer microneedles whose outer diameter gradually decreases from distal to proximal. Each hydrogel monomer microneedle expands or contracts upon contact with interstitial fluid based on changes in glucose concentration, converting changes in glucose concentration in the interstitial fluid into changes in microneedle length. The particles are placed inside the tips and / or bodies of each individual microneedle and are used to enhance the ultrasonic echo recognition at the tip position. The control and data processing module includes a TOF extraction module, an averaging calculation module, and a concentration mapping module. The TOF extraction module is used to analyze and process the ultrasonic echo signals acquired by the transmitting and receiving circuits and extract the time-of-flight parameters corresponding to each gated region. The averaging calculation module is used to calculate the local length change corresponding to each gated region based on the time-of-flight difference data obtained by the TOF extraction module, and further obtain the overall average change. The concentration mapping module is used to calculate the concentration information of the analyte based on the average length change ΔLavg obtained by the averaging calculation module, combined with a pre-established concentration calibration model, and feed it back to the mobile terminal module for continuous monitoring of blood glucose concentration.

[0014] According to a specific embodiment and preferred aspect of the present invention, the area covered by the ultrasound probe is divided into multiple array measurement regions based on a microneedle patch. A TOF extraction module extracts information from each array measurement region, obtaining a local TOF change ΔTOFi for each sub-array measurement region. The local length change ΔLi is further calculated, and multiple ΔLi values ​​are averaged, weighted averaged, or averaged after outlier removal to obtain the average length change ΔLavg of the microneedle array. This multi-region averaging process reduces the impact of local tissue heterogeneity, probe coupling fluctuations, and individual microneedle measurement errors on the results, improving measurement stability and repeatability.

[0015] Preferably, the TOF extraction module extracts the time-of-flight parameters corresponding to each gated region, and identifies the positions of the reference echo and the target echo through peak detection, envelope extraction, cross-correlation analysis, or threshold determination methods, and calculates the time-of-flight difference ΔTOFi between them. This time-of-flight difference reflects the change in the acoustic propagation path caused by the change in the length of the microneedle patch within the corresponding gated region, providing basic data for subsequent length change calculations.

[0016] In some specific implementations, for the i-th gated region, the averaging module calculates the local length change according to the following formula: ΔLi=(c×ΔTOFi) / 2, where c is the velocity of sound in the interstitial fluid and ΔTOFi is the time-of-flight change of the corresponding region. In actual processing, the averaging module can also remove local regions with low echo signal-to-noise ratio, missing echoes, or abnormal changes, and can also use weighted averaging, moving average, or median filtering to improve measurement stability.

[0017] Preferably, the average length change is: ΔLavg = (ΔL1 + ΔL2 + ... + ΔLN) / N, where N is the number of gated regions involved in the measurement. Averaging across multiple gated regions not only reduces the impact of individual microneedle preparation errors, local adhesion pressure variations, skin tissue differences, and motion interference on the final results, but also reduces the influence of local tissue heterogeneity, probe coupling fluctuations, and individual microneedle measurement errors on the results, thus improving measurement stability and repeatability.

[0018] Specifically, the concentration mapping module uses the mapping relationship obtained from experimental calibration: C = k × ΔLavg + b, where C is the concentration to be measured; k is the calibration slope; b is the calibration intercept; and ΔLavg is the average length change. The preferred concentration to be measured is glucose concentration. The concentration mapping module can further establish concentration conversion relationships using methods such as linear fitting, polynomial fitting, lookup table mapping, machine learning models, or neural network models to improve the accuracy of concentration prediction. The concentration mapping module sends the calculated concentration results to a mobile terminal for real-time display, storage, and trend analysis, thereby achieving continuous monitoring of interstitial fluid glucose concentration.

[0019] According to another specific embodiment and preferred aspect of the present invention, the plurality of array measurement regions include a center region, an edge region, an upper left region, an upper right region, a lower left region, and a lower right region; Each array element includes a piezoelectric ceramic sheet, a front matching layer, a backing layer, an electrode layer, an insulating encapsulation layer, and a conductive connection. The front matching layer is used to improve the acoustic impedance matching between the array element and the acoustic coupling layer, microneedle patch, or skin. The backing layer is used to absorb reverse acoustic waves and shorten the ringing time. The electrode layer is used to realize the electrical connection between the array element and the transmitting and receiving circuit or the gating array switch. Under the control of the gating array switch, different array elements or different arrays are transmitted and received. And / or, the gating array switch is a multi-channel analog switch, a high-voltage ultrasonic switch matrix, a MEMS switch, a CMOS switch array, or other switch structures that can withstand ultrasonic transmission voltage and are suitable for high-frequency echo transmission.

[0020] In short, it can achieve single-element gating, row-column gating, subarray gating, or full-array partition gating. Single-element gating is suitable for high spatial resolution measurements; subarray gating is suitable for improving echo signal-to-noise ratio and reducing the number of channels; full-array partition gating is suitable for rapidly scanning the entire microneedle patch. That is, with the help of gating array switches, the system can perform ultrasonic measurements on different local areas of the microneedle patch in sequence, instead of always measuring only a single point. Therefore, it can significantly reduce the impact of individual microneedle abnormalities, poor local adhesion, or local tissue differences on the detection results.

[0021] According to another specific embodiment and preferred aspect of the invention, a flexible substrate is located at the proximal end of the hydrogel microneedle array to fix multiple hydrogel monomer microneedles and provide overall support for the patch, enabling the hydrogel monomer microneedles to adapt to the curvature and deformation of the skin surface during tissue insertion. In short, it not only provides mechanical support when the microneedles contact the skin, allowing them to penetrate the tissue uniformly, but also adapts to the curvature and deformation of the skin surface, ensuring no gaps appear when the microneedle patch is applied. This enhances the elasticity of the flexible substrate, allowing the microneedles to apply moderate pressure to the skin surface, improving tissue penetration efficiency, while simultaneously supporting the vertical stability of the microneedles and preventing them from tilting during scanning or use.

[0022] Preferably, the hydrogel microneedle array is arranged based on the element spacing, acoustic beam coverage, and patch size, and the hydrogel microneedles are glucose-responsive hydrogels, pH-responsive hydrogels, ion-responsive hydrogels, or other polymer hydrogels that have a volume response to changes in the concentration of the target analyte. The hydrogel microneedle array can be arranged in a 5×5, 8×8, 10×10, or other two-dimensional array configuration, and the microneedle spacing can be designed according to the element spacing of the area array probe, the acoustic beam coverage, and the patch size.

[0023] Preferably, the acoustic enhancement particles can be silicon microspheres, silica microparticles, metal oxide microparticles, bubble structures, acoustic impedance difference particles, or other materials that can enhance ultrasonic scattering and reflection. With acoustic enhancement particles, the system can more easily identify the pinhead echo peak from the echo signal.

[0024] According to another specific embodiment and preferred aspect of the present invention, a wearable ultrasound module is disposed above or integrated with the microneedle patch; the wearable ultrasound module is a patch type, wristband type, armband type, or flexible encapsulation structure; a communication module, a control and data processing module, a transmitting and receiving circuit, a gating array switch, a power supply module, and an ultrasound probe are housed within the shell of the wearable ultrasound module, and the lower surface of the wearable ultrasound module is in contact with the microneedle patch or the acoustic coupling layer, so that the ultrasound emitted by the ultrasound probe can pass through the coupling layer and the flexible substrate to reach the area of ​​the hydrogel microneedle array.

[0025] According to another specific embodiment and preferred aspect of the present invention, the transmitting and receiving circuit works in conjunction with the gating array switch, wherein the control and data processing module first controls the gating array switch to select a certain array element or a certain subarray, and then the transmitting and receiving circuit performs ultrasonic transmission and reception on the selected area.

[0026] Preferably, the transmitting and receiving circuit is connected to the gating array switch and the ultrasonic probe to generate short-pulse ultrasonic transmission signals and receive echo signals returned by the array elements, wherein the transmission pulse is a unipolar pulse, bipolar pulse, narrow pulse, coded pulse or other excitation signal suitable for TOF ranging.

[0027] Preferably, the transmit / receive circuit includes a high-voltage pulse generator, a transmit / receive switching circuit, a low-noise amplifier, a bandpass filter, a variable gain amplifier, and an analog-to-digital converter. To accommodate high-frequency TOF measurements at around 30MHz, the sampling rate can be set to 100MS / s to 500MS / s or higher.

[0028] In addition, the mobile terminal is used to receive data sent by the wireless communication module and to display, record, analyze, and manage the monitoring results. The mobile terminal can be a smartphone, laptop, desktop computer, or dedicated monitoring terminal, and its functions may include receiving system data in real time and displaying real-time concentration values; displaying concentration change trends; storing historical monitoring data; setting alarm thresholds; setting sampling periods; and enabling user interaction and parameter configuration.

[0029] In some specific implementations, the wireless communication module is communicatively connected to the control and data processing module to send calculation results to the mobile terminal. The wireless communication module uses BLE, Wi-Fi, NFC, or other communication methods, and the data it sends includes average length change, concentration value, concentration trend curve, alarm information, device operating status, and signal quality information.

[0030] Based on this, the measured change in microneedle length is input into a pre-established concentration calibration model and converted into the concentration value of the target substance. This concentration calibration model is established using methods such as linear fitting, polynomial fitting, lookup table mapping, machine learning models, or neural network models. These methods are commonly used concentration conversion modeling techniques in this field and can be flexibly selected according to the actual data characteristics to ensure the accuracy and robustness of concentration inversion.

[0031] Due to the implementation of the above technical solutions, the present invention has the following advantages compared with the prior art: In existing wearable continuous analytical monitoring, the length changes of hydrogel microneedles are often difficult to read in real time while worn on the skin. That is, after the hydrogel microneedles enter the interstitial fluid, their tip position and degree of expansion are obscured by the patch, skin, and tissue, making continuous observation difficult using traditional microscopy or optical imaging methods. Removing the patch for measurement not only disrupts the continuous monitoring process but also alters the microneedle state and tissue environment. Furthermore, single-point TOF measurements lack representativeness and are easily affected by local errors. Specifically, microneedle patches typically consist of multiple microneedles, and the expansion rate and length changes of different microneedles may vary. When measuring a local location with a single acoustic beam, local contact pressure, microneedle breakage, air bubbles, poor coupling, or uneven tissue fluid distribution can significantly affect the results. Finally, there is a lack of spatial correspondence and arrayed readout structure between the microneedle patch and the ultrasound module. While ordinary ultrasound probes can transmit and receive ultrasound signals, they may not correspond to the arrangement, spacing, and measurement area of ​​the microneedle array, easily leading to acoustic beam overlay. The existing wearable blood glucose continuous monitoring system suffers from several shortcomings, including range uncertainty, mixed echo sources, and repeated measurements in local areas. Furthermore, the system lacks robustness to motion, adhesion pressure, and coupling changes. Specifically, users may experience arm movements, skin deformation, slight patch slippage, or changes in coupling layer thickness during daily wear. If the system uses only absolute TOF or a single echo peak, drift is likely. This invention, based on the overall design of a two-dimensional area array ultrasound gating array, cleverly solves these shortcomings. Using this system, a microneedle patch is first attached to the skin surface, allowing the hydrogel microneedles to penetrate the superficial skin layer and contact the skin tissue / interstitial fluid area. Secondly, the control and data processing module generates control commands according to a preset sampling period, controlling the gating array switch to select one, multiple, or a sub-array region of the two-dimensional area array ultrasound probe. The selected array region and the corresponding microneedle region in the microneedle patch form a spatial correspondence, completing the array selection.Finally, the control and data processing module controls the transmitting and receiving circuit to generate an ultrasonic excitation signal. The transmitting and receiving circuit transmits the electrical pulse signal to the selected array element or subarray in the two-dimensional area array ultrasound probe, causing it to emit short-pulse ultrasonic waves towards the corresponding microneedle patch area. After the ultrasonic waves propagate to the microneedle patch, echo signals are generated at the acoustic impedance change interfaces in the microneedle patch base interface, microneedle body, microneedle tip, and skin tissue / interstitial fluid region. The echo signals are received by the two-dimensional area array ultrasound probe and returned to the control and data processing module via the gating array switch and the transmitting and receiving circuit. The reference echo can come from the base interface of the microneedle patch or other relative... With a fixed acoustic interface, the tip echo can originate from the tip region of the hydrogel microneedles, acoustic enhancement particles, or the interface with acoustic impedance differences near the tip. When changes in the target analyte concentration cause the hydrogel microneedles to expand or contract, the microneedle tip position changes relative to the reference interface, and the arrival time of the tip echo also changes accordingly. The Time-of-Flight (TOF) extraction module obtains the time-of-flight change ΔTOFi corresponding to the i-th gated region by comparing the time-of-flight difference between the baseline state and the current state. The averaging calculation module calculates the local length change ΔLi of the i-th gated region based on the time-of-flight change ΔTOFi obtained by the TOF extraction module. Subsequently... The control and data processing module controls the gating array switch to sequentially switch to the next array element or subarray region, and repeats the process of ultrasonic transmission, echo reception, TOF extraction, and local length change calculation. After completing one round of array scanning, the system obtains the local length changes ΔL1, ΔL2, ..., ΔLN corresponding to multiple gating regions. The averaging module performs statistical processing on the multiple local length changes to obtain the overall average length change ΔLavg of the microneedle patch. Combined with a pre-established concentration calibration model, the average length change of the microneedle patch is converted into the target analyte concentration C or concentration change trend. After completing the concentration calculation, the control and data processing module... The processing module transmits information such as average length change, concentration calculation results, measurement time, signal quality, and device status to the wireless communication module. The wireless communication module sends the data to the mobile terminal via Bluetooth, Wi-Fi, or other wireless communication methods. The mobile terminal displays the concentration value, concentration change trend, historical data, and alarm information in real time, and can send control commands such as sampling period, alarm threshold, or calibration parameters to the control and data processing module. Therefore, this invention, on the one hand, is based on wearable microneedle patches and ultrasonic probes, and uses the TOF difference between the tip echo and the reference echo to realize non-optical microneedle length change reading, avoiding the defects of optical detection being susceptible to interference.On the other hand, by establishing the correspondence between array elements and microneedle regions through an array element gating system, local TOF data with spatial indexes is obtained through group gating. ΔLavg is obtained through statistical processing such as averaging, weighted averaging, and outlier removal, enabling parallel measurement of multiple regions, reducing the impact of single-point anomalies, and significantly improving the stability and reliability of continuous monitoring. Simultaneously, the flexible substrate provides mechanical support for microneedle insertion into the skin, adapts to surface curvature deformation, and prevents microneedle tilting during scanning. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the wearable array gated TOF microneedle patch continuous monitoring system of the present invention.

[0033] Figure 2 for Figure 1 Schematic diagram of the structure of the microneedle patch; Figure 3 for Figure 1 Schematic diagram of micro-needle patch, two-dimensional array probe and array element gating structure; Figure 4 A block diagram of the array element gating TOF measurement, average length change calculation, and concentration mapping system.

[0034] The module comprises: 1. Mobile terminal module; 2. Wireless communication module; 3. Control and data processing module; 31. TOF extraction module; 32. Average calculation module; 33. Concentration mapping module; 4. Transmitter and receiver circuit; 5. Gating array switch; 6. Power supply module; 7. Two-dimensional area array ultrasound probe (hereinafter referred to as ultrasound probe); 71. Array element; 72. Array; 8. Microneedle patch; 81. Flexible substrate; 82. Hydrogel microneedle array; 83. Acoustic enhancement microparticles; 9. Skin; 91. Epidermal layer of skin; 92. Dermal layer of skin; 93. Interstitial fluid region; 10. Wearable ultrasound module. Detailed Implementation

[0035] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0036] like Figures 1 to 3As shown, the wearable continuous blood glucose monitoring system based on a two-dimensional area array ultrasound gating array in this embodiment comprises a mobile terminal module 1, a wireless communication module 2, a control and data processing module 3, a transmit and receive circuit 4, a gating array switch 5, a power supply module 6, a two-dimensional area array ultrasound probe 7, a microneedle patch 8, and a wearable ultrasound module 10. The microneedle patch 8 is used to contact the skin 9 and allow the hydrogel microneedles to enter the interstitial fluid; the two-dimensional area array ultrasound probe 7 is used to cover the microneedle array and perform gating measurements on different array elements or subarrays; the control and data processing module 3 is used to complete TOF extraction, local length change calculation, average change calculation, and concentration mapping; and the wireless communication module 2 is used to send the processing results to the mobile terminal 1 for display and alarm.

[0037] Specifically, the mobile terminal module 1 (mobile terminal / PC) is used to receive data sent by the wireless communication module 2 and to display, record, analyze, and manage the monitoring results. In this example, the mobile terminal / PC can be a smartphone, laptop, desktop computer, or dedicated monitoring terminal, and its functions include receiving system data in real time, displaying real-time concentration values, displaying concentration change trends, storing historical monitoring data, setting alarm thresholds, setting sampling periods, and performing user interaction and parameter configuration.

[0038] The wireless communication module 2 is connected to the control and data processing module 3 to send the calculation results to the mobile terminal / PC. The wireless communication module 2 adopts BLE, Wi-Fi, NFC or other communication methods. The data sent may include the average length change, concentration value, concentration trend curve, alarm information, equipment working status and signal quality information.

[0039] The control and data processing module 3 is the core control unit of this system and can be implemented using an MCU, FPGA, DSP, ASIC, or other embedded processor. In some specific embodiments, the control and data processing module 3 includes a TOF extraction module 31, an averaging calculation module 32, and a concentration mapping module 33, used to complete ultrasonic echo data processing and concentration calculation. It controls the timing of the gating array switch 5 to achieve sequential scanning of different gating regions by the two-dimensional area array ultrasonic probe 7; it controls the transmitting and receiving circuit 4 to complete ultrasonic excitation, echo reception, and signal acquisition; it receives the ultrasonic echo signals corresponding to each gating region and completes data preprocessing. In some specific embodiments, the TOF extraction module 31 is used to analyze and process the ultrasonic echo signals acquired by the transmitting and receiving circuit 4 to extract the Time of Flight (TOF) parameters corresponding to each gating region. Specifically, the TOF extraction module 31 receives echo data acquired by the two-dimensional area array ultrasound probe 7, identifies the positions of the reference echo and the target echo through methods such as peak detection, envelope extraction, cross-correlation analysis, or threshold determination, and calculates the time-of-flight difference ΔTOFi between them. This time-of-flight difference reflects the change in the sound propagation path caused by the change in the length of the microneedle patch 8 within the corresponding gated region, providing basic data for subsequent length change calculations. The averaging calculation module 32 is used to calculate the local length change corresponding to each gated region based on the time-of-flight difference data obtained by the TOF extraction module 31, and further obtains the overall average change. Specifically, for the i-th gated region, the averaging calculation module 32 calculates the local length change according to the following formula: ΔLi=(c×ΔTOFi) / 2, where c is the sound velocity in the interstitial fluid, and ΔTOFi is the time-of-flight change of the corresponding region. Subsequently, the averaging module 32 performs statistical analysis on the local length changes of multiple gated regions, calculating the average length change: ΔLavg = (ΔL1 + ΔL2 + ... + ΔLN) / N, where N is the number of gated regions involved in the measurement. Multi-region averaging reduces the impact of local tissue heterogeneity, probe coupling fluctuations, and individual microneedle measurement errors on the results, improving measurement stability and repeatability. The concentration mapping module 33 calculates the analyte concentration information based on the average length change ΔLavg obtained from the averaging module 32, combined with a pre-established concentration calibration model. Specifically, the concentration mapping module 33 uses the mapping relationship obtained from experimental calibration: C = k × ΔLavg + b, where C is the analyte concentration; k is the calibration slope; b is the calibration intercept; and ΔLavg is the average length change. In this embodiment, the analyte concentration is preferably glucose concentration. The concentration mapping module 33 can further establish concentration conversion relationships using linear fitting, polynomial fitting, lookup table mapping, machine learning models, or neural network models to improve concentration prediction accuracy.The concentration mapping module 33 sends the calculated concentration results to the mobile terminal 1 for real-time display, storage and trend analysis, thereby realizing continuous monitoring of interstitial fluid glucose concentration.

[0040] The transmit / receive circuit 4 is connected to the gating array switch 5 and the two-dimensional area array ultrasonic probe 7. It generates short-pulse ultrasonic transmission signals and receives echo signals returned from the array elements. The transmission pulse can be a unipolar pulse, bipolar pulse, narrow pulse, coded pulse, or other excitation signal suitable for TOF ranging. The transmit / receive circuit 4 includes a high-voltage pulse generator, a transmit / receive switching circuit, a low-noise amplifier, a bandpass filter, a variable gain amplifier, and an analog-to-digital converter. To accommodate high-frequency TOF measurements of approximately 30MHz, the sampling rate can be set from 100MS / s to 500MS / s or higher. The transmit / receive circuit 4 works in conjunction with the gating array switch 5; that is, the control and data processing module 3 first controls the gating array switch 5 to select a specific array element or subarray, and then the transmit / receive circuit 4 performs ultrasonic transmission and reception on the selected area.

[0041] The gating array switch 5 is electrically connected to multiple array elements 71 of the two-dimensional area array ultrasonic probe 7, and is used to select the array elements 71 or array 72 participating in transmission and reception under the control of the control and data processing module 3. The gating array switch 5 can be a multi-channel analog switch, a high-voltage ultrasonic switch matrix, a MEMS switch, a CMOS switch array, or other switch structures that can withstand ultrasonic transmission voltage and are suitable for high-frequency echo transmission. It can realize single-element gating, row and column gating, sub-array gating, or full-array partition gating. Single-element gating is suitable for high spatial resolution measurement; sub-array gating is suitable for improving the echo signal-to-noise ratio and reducing the number of channels; full-array partition gating is suitable for rapid scanning of the entire microneedle patch 8. With the help of the gating array switch 5, the system can perform ultrasonic measurements on different local areas of the microneedle patch 8 in sequence, instead of always measuring only a single point, thus significantly reducing the impact of individual microneedle abnormalities, poor local adhesion, or local tissue differences on the detection results.

[0042] The power module 6 provides operating power to the control and data processing module 3, the transmit and receive circuit 4, the gating array switch 5, and the wireless communication module 2. The power module 6 can be powered by a battery, a rechargeable lithium battery, or an external DC power supply. In wearable applications, the power module 6 preferably adopts a miniaturized, low-power design to meet the requirements of long-term continuous monitoring.

[0043] An ultrasound probe 7 (two-dimensional array ultrasound probe) is positioned above the microneedle patch 8 and spatially opposite to it. The two-dimensional array ultrasound probe 7 comprises multiple array elements arranged in a two-dimensional matrix. These elements are used to transmit ultrasound signals to the corresponding area of ​​the microneedle patch 8 and to receive echo signals from the microneedle patch and its associated interfaces. The two-dimensional array ultrasound probe 7 consists of multiple array elements 71 arranged in a two-dimensional matrix, such as 8×8, 16×16, 32×32, or other array configurations corresponding to the microneedle array. The function of the two-dimensional array ultrasound probe 7 is not simply to obtain traditional ultrasound echoes, but rather to cover multiple microneedle areas of the microneedle patch 8 and, under the control of the gating array switch 5, to transmit and receive different array elements 71 or different arrays 72. The operating frequency of the two-dimensional array ultrasound probe 7 is preferably between 20MHz and 50MHz, and more preferably approximately 30MHz, to balance echo signals at the microneedle scale with propagation capabilities within superficial tissues. Specifically, array element 71 is the basic transmitting and receiving unit in the two-dimensional array ultrasound probe 7. Each array element 71 may include a PZT piezoelectric ceramic sheet, a front matching layer, a backing layer, an electrode layer, an insulating encapsulation layer, and a conductive connection. The PZT piezoelectric ceramic sheet is used to convert electrical pulses into ultrasonic pulses and to convert the returned ultrasonic echoes into electrical signals. The front matching layer is used to improve the acoustic impedance matching between the array element and the acoustic coupling layer, microneedle patch, or skin, thereby improving the ultrasonic energy transmission efficiency. The backing layer is used to absorb the reverse sound waves and shorten the ringing time, thereby improving the axial resolution. The electrode layer is used to realize the electrical connection between the array element 71 and the transmitting and receiving circuit 4 or the gating array switch 5.

[0044] In this example, the size, spacing, and arrangement of the array elements 71 match the size, spacing, and regional distribution of the hydrogel microneedle array 82. One array element 71 can correspond to one microneedle or multiple microneedles; one subarray can correspond to a measurement zone in the microneedle patch 8. Simultaneously, a local measurement unit composed of one or more array elements 71 is used to perform TOF measurements on one or more microneedles in the corresponding region of the microneedle patch 8. The system can divide the entire microneedle patch 8 into multiple array measurement regions 72, such as the central region, edge region, upper left region, upper right region, lower left region, and lower right region. Each subarray measurement region 72 can obtain a local TOF change ΔTOFi, and further calculate the local length change ΔLi. The control and data processing module 3 averages, weights, or removes outliers from multiple ΔLi values ​​and then averages the results to obtain the average length change ΔLavg of the microneedle array.

[0045] The microneedle patch 8 is the sensitive component of this system that comes into contact with human skin, and is attached to the surface of the skin tissue / interstitial fluid region 9. The microneedle patch 8 includes a flexible substrate 81, a hydrogel microneedle array 82, and acoustically reinforcing microparticles 83. After the microneedle array is inserted into the superficial layer of the skin, it comes into contact with the interstitial fluid. When the concentration of the target analyte changes, the microneedle material will expand, contract, change length, or change the position of the equivalent acoustic interface. This change is the object of ultrasound measurement in this system. In a preferred embodiment, the microneedle patch 8 is a hydrogel microneedle patch, suitable for continuous monitoring of target analytes such as glucose, lactic acid, uric acid, electrolytes, or other analytes that can cause changes in the morphology of the microneedles. Specifically, the flexible substrate 81 is located at the proximal end of the hydrogel microneedle array 82. It is used to fix multiple microneedles and provide overall support for the patch, carrying the hydrogel microneedles 82 and acoustic enhancement microparticles 83, maintaining the stability of the microneedle arrangement, providing mechanical support when the microneedles contact the skin, enabling the microneedles to penetrate the tissue uniformly; adapting to the curvature and deformation of the skin surface, ensuring no gaps appear when the microneedle patch is applied; the elasticity of the flexible substrate allows the microneedles to apply moderate pressure to the skin surface, improving tissue penetration efficiency; and supporting the vertical stability of the microneedles, preventing them from tilting during scanning or use. The hydrogel microneedle array 82 is arranged in a 5×5, 8×8, 10×10, or other two-dimensional array configuration. The microneedle spacing can be designed according to the element spacing of the area array probe, the acoustic beam coverage, and the patch size. The microneedle material can be glucose-responsive hydrogel, pH-responsive hydrogel, ion-responsive hydrogel, or other polymer materials that have a volume response to changes in the concentration of the target analyte. Acoustic enhancing microparticles 83 are disposed in the tip region and inside the needle body of the hydrogel microneedle array 82 to improve the ultrasonic echo recognition at the needle tip position. The acoustic enhancing microparticles 83 are made of silicon microspheres, silica microparticles, metal oxide microparticles, bubble structures, acoustic impedance difference particles, or other materials capable of enhancing ultrasonic scattering and reflection. Through the acoustic enhancing microparticles 83, the system can more easily identify the needle tip echo peak from the echo signal. In the actual working environment of the microneedle patch 8, after the microneedle array is inserted into the superficial layer of the skin 9 (including the epidermal layer 91, dermal layer 92, and interstitial fluid region 93), the needle body interacts with the interstitial fluid. Changes in the concentration of the target analyte in the interstitial fluid will cause changes in the structural parameters of the microneedle. Since the distribution of interstitial fluid, local pressure, adhesion state, and individual differences may vary in different local areas, this invention employs multi-regional ultrasonic gating measurement and averaging to improve the representativeness and stability of the final results.

[0046] The wearable ultrasound module 10 is positioned above or integrated with the microneedle patch 8, and is used to house the two-dimensional array ultrasound probe 7, the acoustic coupling layer, the transmitting and receiving circuit 4, the gating array switch 5, some control circuits, the power supply, and the housing structure. The housing of the wearable ultrasound module 10 can be a patch, wristband, armband, or flexible encapsulation structure; and the lower surface of the wearable ultrasound module 10 is in contact with the microneedle patch 8 or the acoustic coupling layer, so that the ultrasound emitted by the two-dimensional array ultrasound probe 7 can pass through the coupling layer and the flexible substrate 81 to reach the area of ​​the hydrogel microneedle array 82.

[0047] In summary, this embodiment employs a working method that utilizes microneedle patch response, two-dimensional area array ultrasonic probe detection, gated array partitioning measurement, Time-of-Flight (TOF) extraction, average change calculation, and concentration mapping to achieve continuous monitoring of target analyte concentration changes in interstitial fluid. The specific process is as follows: 1) The microneedle patch 8 is attached to the surface of human skin, so that the hydrogel microneedles in the microneedle patch 8 penetrate into the superficial layer of the skin and come into contact with the skin tissue / interstitial fluid area 9. The hydrogel microneedles can absorb the interstitial fluid and change in length, volume or needle tip position as the concentration of the target analyte in the interstitial fluid changes. Taking glucose monitoring as an example, when the glucose concentration in the interstitial fluid changes, the hydrogel microneedles expand or contract accordingly, causing a detectable change in the length of the microneedle or the position of the needle tip. 2) The wearable ultrasound module 10 is positioned above the microneedle patch 8. A two-dimensional array ultrasound probe 7 is installed within the wearable ultrasound module 10. The two-dimensional array ultrasound probe 7 and the microneedle patch 8 are spatially opposite each other. The probe 7 is used to transmit ultrasound signals to the area where the microneedle patch 8 is located and to receive echo signals from the microneedle patch 8 and the skin / interstitial fluid area 9. The power module 6 provides operating power to the control and data processing module 3, the transmitting and receiving circuit 4, the gating array switch 5, and the wireless communication module 2. The control and data processing module 3 generates control commands according to a preset sampling period, controlling the gating array switch 5 to select one element, multiple elements, or a sub-array area of ​​the two-dimensional array ultrasound probe 7. The selected element area and the corresponding microneedle area in the microneedle patch 8 form a spatial correspondence to complete the element selection. 3) The control and data processing module 3 controls the transmitting and receiving circuit 4 to generate an ultrasonic excitation signal. The transmitting and receiving circuit 4 transmits the electrical pulse signal to the selected array element or subarray in the two-dimensional area array ultrasonic probe 7, causing it to emit short-pulse ultrasonic waves to the corresponding microneedle patch area. After the ultrasonic waves propagate to the microneedle patch 8, echo signals are generated at the acoustic impedance change interfaces in the base interface, microneedle body, microneedle tip, and skin tissue / interstitial fluid region 9 of the microneedle patch 8. The echo signals are received by the two-dimensional area array ultrasonic probe 7 and returned to the control and data processing module 3 via the selection array switch 5 and the transmitting and receiving circuit 4. During the reception process, the transmitting and receiving circuit 4 can perform amplification, filtering, transmit / receive isolation, and analog-to-digital conversion on the echo signals to obtain digital echo data that can be used for subsequent calculations. The control and data processing module 3 is internally equipped with a TOF extraction module 31, an averaging calculation module 32, and a concentration mapping module 33. The TOF extraction module 31 is used to analyze the echo signals of each selected area, identify the reference echo and the needle tip echo, and extract the time-of-flight difference between them. The reference echo can originate from the substrate interface of the microneedle patch 8 or other relatively fixed acoustic interfaces. The tip echo can originate from the tip region of the hydrogel microneedle, acoustic enhancement particles, or interfaces with acoustic impedance differences near the tip. When the concentration of the target analyte changes, causing the hydrogel microneedle to expand or contract, the position of the microneedle tip relative to the reference interface changes, and the arrival time of the tip echo also changes accordingly. The TOF extraction module 31 obtains the time-of-flight change ΔTOFi corresponding to the i-th gating region by comparing the time-of-flight difference between the reference state and the current state. The averaging calculation module 32 calculates the local length change ΔLi of the i-th gating region based on the time-of-flight change ΔTOFi obtained by the TOF extraction module 31. Subsequently, the control and data processing module 3 controls the gating array switch 5 to switch to the next array element in sequence. The system scans an array region and repeats the process of ultrasonic transmission, echo reception, TOF extraction, and local length change calculation. After completing one round of array scanning, the system obtains the local length changes ΔL1, ΔL2, ..., ΔLN corresponding to multiple gated regions. The average calculation module 32 performs statistical processing on the multiple local length changes to obtain the overall average length change ΔLavg of the microneedle patch 8. The concentration mapping module 33 converts the average length change ΔLavg output by the average calculation module 32 into the target analyte concentration C or concentration change trend based on the pre-established concentration calibration model. Depending on the application scenario, the concentration mapping module 33 can also use a piecewise linear model, a polynomial model, a lookup table model, a temperature compensation model, or an individualized calibration model for concentration conversion.

[0048] 4) After the concentration calculation is completed, the control and data processing module 3 transmits information such as the average length change, concentration calculation result, measurement time, signal quality and equipment status to the wireless communication module 2. The wireless communication module 2 sends the data to the mobile terminal via Bluetooth, Wi-Fi or other wireless communication methods. The mobile terminal is used to display the real-time concentration value, concentration change trend, historical data and alarm information, and can send control commands such as sampling period, alarm threshold or calibration parameters to the control and data processing module.

[0049] In short, unlike single-point TOF measurements, this invention utilizes array element gating and multi-region averaging processing of a two-dimensional area array probe to ensure that monitoring results are independent of a single microneedle or a specific local acoustic beam path. This approach improves the stability, representativeness, and anti-interference capabilities of continuous monitoring of microneedle patches, making it suitable for continuous monitoring of interstitial fluid analyte concentrations under wearable conditions. Even if some microneedles exhibit abnormal echoes due to adhesion pressure, material defects, poor local coupling, or motion interference, the system can mitigate the impact of errors through multi-region data fusion. Furthermore, this invention can employ multiple measurement modes to meet different application requirements: in low-power mode, the system selects only a small number of representative subarrays for rapid averaging; in high-precision mode, the system selects more array elements or subarrays to obtain a more complete spatial distribution; in self-test mode, the system compares the echo intensity of the edge and center regions to determine whether the patch is well-attached or whether there is local detachment.

[0050] In summary, this embodiment has the following advantages: 1) Changes in glucose concentration are reflected by changes in microneedle length. This patent utilizes the property that responsive hydrogel microneedles expand or contract upon contact with interstitial fluid in response to changes in glucose concentration, converting changes in glucose concentration in the interstitial fluid into changes in microneedle length. Compared to detection methods that directly rely on electrochemical reactions or optical color changes, this approach provides a continuous glucose monitoring pathway based on microneedle structural deformation, enabling the observation of changes in the average length of the microneedles to reflect trends in glucose concentration.

[0051] 2) Use the ultrasonic TOF method to read the changes in microneedle length. This patent does not rely on microscopic observation, optical image recognition, or manual measurement of microneedle morphology. Instead, it uses a two-dimensional array ultrasonic probe to emit ultrasonic signals to the microneedle patch and calculates the position or length change of the microneedle tip using the time-of-flight (TOF) difference. This method enables non-optical, non-contact readout while the microneedle patch is attached to the skin surface, making it more suitable for wearable continuous monitoring scenarios.

[0052] 3) Area array coverage A two-dimensional area array ultrasonic probe is used to cover the microneedle patch array, so that the measurement area corresponds to the entire microneedle array, rather than measuring only a single point.

[0053] 4) Array element selection By selecting different array elements or subarrays sequentially or in groups using the gating array switch, a flexible balance can be achieved between the number of channels, power consumption, and measurement accuracy.

[0054] 5) Measurement of average change The average length variation ΔLavg of the microneedle array is calculated using TOF data from multiple gating regions, reducing the impact of single microneedle errors and local tissue differences on the results.

[0055] 6) Strong anti-interference ability By utilizing the TOF difference between the reference echo and the tip echo, and combining it with outlier removal, moving average, or weighted average processing, stability under motion, pressure, and coupling changes can be improved.

[0056] 7) High structural integration Microneedle patches, area array probes, gating circuits, TOF extraction, wireless communication, and mobile display can be integrated into a wearable system suitable for everyday use.

[0057] 8) The solution of the present invention can not only be used for long-term real-time wearable blood glucose monitoring, but also monitor pH value, specific ion concentration, etc. by replacing microneedle materials such as glucose-responsive hydrogel, pH-responsive hydrogel, ion-responsive hydrogel or other polymer materials that have volume response to changes in the concentration of target analytes.

[0058] The present invention has been described in detail above, with the aim of enabling those skilled in the art to understand and implement the invention. However, this description should not be construed as limiting the scope of protection of the invention. All equivalent changes or modifications made in accordance with the spirit and essence of the invention should be included within the scope of protection of the invention.

Claims

1. A wearable continuous blood glucose monitoring system based on a two-dimensional area array ultrasonic gating array, comprising a mobile terminal module, a communication module, a control and data processing module, a transmitting and receiving circuit, a gating array switch, a power supply module, an ultrasonic probe, a microneedle patch, and a wearable ultrasonic module, characterized in that, The ultrasound probe comprises multiple array elements arranged in a two-dimensional matrix; the microneedle patch comprises a flexible substrate, a hydrogel microneedle array, and acoustic enhancement microparticles. The hydrogel microneedle array is arranged in a two-dimensional array based on the area covered by the ultrasound probe, and includes hydrogel monomer microneedles whose outer diameter gradually decreases from the distal to the proximal end. Each hydrogel monomer microneedle expands or contracts upon contact with interstitial fluid due to changes in glucose concentration, converting changes in glucose concentration in the interstitial fluid into changes in microneedle length. The acoustic enhancement microparticles are disposed within the tips and / or bodies of each monomer microneedle and are used to enhance the ultrasound echo recognition at the tip position. A control and data processing module is included. The system includes a Time-of-Flight (TOF) extraction module, an averaging calculation module, and a concentration mapping module. The TOF extraction module analyzes and processes the ultrasonic echo signals acquired by the transmitting and receiving circuits to extract the time-of-flight parameters corresponding to each gated region. The averaging calculation module calculates the local length change corresponding to each gated region based on the time-of-flight difference data obtained by the TOF extraction module, and further obtains the overall average change. The concentration mapping module calculates the concentration information of the analyte based on the average length change ΔLavg obtained by the averaging calculation module, combined with a pre-established concentration calibration model, and feeds it back to the mobile terminal module for continuous monitoring of blood glucose concentration.

2. The wearable continuous blood glucose monitoring system based on a two-dimensional planar array ultrasonic gating array according to claim 1, characterized in that, The area covered by the ultrasound probe is divided into multiple array measurement areas based on the microneedle patch. The TOF extraction module extracts information from each array measurement area. Each sub-array measurement area can obtain a local TOF change ΔTOFi, and further calculate the local length change ΔLi. At the same time, the average of multiple ΔLi is calculated by averaging, weighted averaging, or removing outliers, to obtain the average length change ΔLavg of the microneedle array.

3. The wearable continuous blood glucose monitoring system based on a two-dimensional planar array ultrasonic gating array according to claim 2, characterized in that, The TOF extraction module extracts the time-of-flight parameters corresponding to each gated region, and identifies the positions of the reference echo and the target echo through peak detection, envelope extraction, cross-correlation analysis or threshold determination methods, and calculates the time-of-flight difference ΔTOFi between them.

4. The wearable continuous blood glucose monitoring system based on a two-dimensional planar array ultrasonic gating array according to claim 3, characterized in that, For the i-th gated region, the average calculation module calculates the local length change according to the following formula: ΔLi=(c×ΔTOFi) / 2, where c is the speed of sound in the interstitial fluid and ΔTOFi is the change in flight time of the corresponding region.

5. The wearable continuous blood glucose monitoring system based on a two-dimensional planar array ultrasonic gating array according to claim 4, characterized in that, Average length change: ΔLavg=(ΔL1+ΔL2+……+ΔLN) / N, where N is the number of gating regions involved in the measurement.

6. The wearable continuous blood glucose monitoring system based on a two-dimensional planar array ultrasonic gating array according to claim 5, characterized in that, The concentration mapping module uses the mapping relationship obtained from experimental calibration: C = k × ΔLavg + b, where C is the concentration to be measured; k is the calibration slope; b is the calibration intercept; and ΔLavg is the average length change.

7. The wearable continuous blood glucose monitoring system based on a two-dimensional planar array ultrasonic gating array according to claim 2, characterized in that, The multiple array measurement areas include the center area, edge area, upper left area, upper right area, lower left area, and lower right area; Each array element includes a piezoelectric ceramic sheet, a front matching layer, a backing layer, an electrode layer, an insulating encapsulation layer, and a conductive connection. The front matching layer is used to improve the acoustic impedance matching between the array element and the acoustic coupling layer, microneedle patch, or skin. The backing layer is used to absorb reverse acoustic waves and shorten the ringing time. The electrode layer is used to realize the electrical connection between the array element and the transmitting and receiving circuit or the gating array switch. Under the control of the gating array switch, different array elements or different arrays are transmitted and received. And / or, the gating array switch is a multi-channel analog switch, a high-voltage ultrasonic switch matrix, a MEMS switch, a CMOS switch array, or other switch structures that can withstand ultrasonic transmission voltage and are suitable for high-frequency echo transmission.

8. The wearable continuous blood glucose monitoring system based on a two-dimensional planar array ultrasonic gating array according to claim 1, characterized in that, The flexible substrate is located at the proximal end of the hydrogel microneedle array to fix multiple hydrogel monomer microneedles and provide overall patch support, so that the hydrogel monomer microneedles can adapt to the curvature and deformation of the skin surface when piercing the tissue. And / or, the hydrogel microneedle array is based on the element spacing, acoustic beam coverage and patch size layout, and the hydrogel microneedles are glucose-responsive hydrogels, pH-responsive hydrogels, ion-responsive hydrogels or other polymer hydrogels that have a volume response to changes in the concentration of the target analyte. And / or, the acoustic enhancement microparticles may be silicon microspheres, silica microparticles, metal oxide microparticles, bubble structures, acoustic impedance difference particles, or other materials that can enhance ultrasonic scattering and reflection.

9. The wearable continuous blood glucose monitoring system based on a two-dimensional planar array ultrasonic gating array according to claim 1, characterized in that, The wearable ultrasound module is positioned above or integrated with the microneedle patch; the wearable ultrasound module is a patch, wristband, armband, or flexible encapsulation structure; the communication module, control and data processing module, transmitting and receiving circuit, gating array switch, power module, and ultrasound probe are housed within the shell of the wearable ultrasound module, and the lower surface of the wearable ultrasound module is in contact with the microneedle patch or acoustic coupling layer, so that the ultrasound emitted by the ultrasound probe can pass through the coupling layer and the flexible substrate to reach the area of ​​the hydrogel microneedle array.

10. The wearable continuous blood glucose monitoring system based on a two-dimensional planar array ultrasonic gating array according to claim 1, characterized in that, The transmitting and receiving circuit works in conjunction with the gating array switch. The control and data processing module first controls the gating array switch to select a certain array element or a certain subarray, and then the transmitting and receiving circuit performs ultrasonic transmission and reception on the selected area. And / or, the transmitting and receiving circuit is connected to the gating array switch and the ultrasonic probe to generate short-pulse ultrasonic transmission signals and receive echo signals returned by the array elements, wherein the transmission pulse is a unipolar pulse, bipolar pulse, narrow pulse, coded pulse or other excitation signal suitable for TOF ranging; And / or, the transmit / receive circuitry includes a high-voltage pulse generator, a transmit / receive switching circuit, a low-noise amplifier, a bandpass filter, a variable gain amplifier, and an analog-to-digital converter.

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