QCM sensor coagulation detection method and system based on amplitude detection

Abstract

The application relates to the fields of sensor technology and coagulation monitoring and relates to a QCM sensor coagulation detection method and system based on amplitude detection, which comprises the following steps: a DDS sweep source outputs a sweep signal; when blood coagulates on the surface of a quartz crystal, the resonance frequency of the quartz crystal changes; a QCM sensor monitors the sweep signal and reacts according to the signal amplitude change of the resonance frequency; the DDS sweep source gradually adjusts the frequency, and the QCM sensor monitors the signal amplitude change; an amplitude demodulation module detects the signal amplitude in real time and feeds back the signal to a single-chip microcomputer; the single-chip microcomputer controls the sweep parameters to control the sweep process of the DDS sweep source, processes the received signal, outputs a measurement result and completes coagulation function monitoring. According to the relationship between the load quality and the signal amplitude change, the amplitude fluctuation in the coagulation process is monitored in real time, so that the resonance frequency change curve of the quartz crystal under different coagulation functions is reflected, the detection precision and stability are improved, and the application prospect is wider.

Description

Technical Field

[0001] This invention relates to the fields of sensor technology and coagulation monitoring technology, and in particular to a coagulation detection method and system based on amplitude detection using a QCM sensor. Background Technology

[0002] Coagulation function monitoring is an indispensable part of clinical diagnosis and treatment, especially in patients undergoing surgery, trauma treatment, and those on long-term anticoagulant medication. Traditional coagulation function tests, such as prothrombin time (PT) and activated partial thromboplastin time (APTT), typically require complex laboratory equipment and involve blood draws and chemical reagent reactions, resulting in problems such as complex operation, long testing cycles, and high patient dependence.

[0003] With the development of medical technology, the demand for portable and real-time monitoring systems is increasing, especially among patients in clinical recovery or at home, who need a device that is easy to carry and can provide real-time feedback on test results. Currently, there is no efficient, accurate, and user-friendly coagulation function testing system available on the market. Therefore, there is an urgent need for a novel testing method that can improve testing accuracy while also facilitating self-monitoring and management by patients.

[0004] Quartz crystal microbalances (QCMs), as high-precision sensors, are widely used in gas, liquid, and biological analysis. The core principle of QCM technology is to utilize the resonant characteristics of quartz crystals at specific frequencies, detecting minute changes in mass by measuring changes in the resonant frequency. According to the Sauerbrey equation, there is a linear relationship between the resonant frequency of a quartz crystal and the mass attached to its surface; therefore, QCMs can measure changes in surface mass with very high accuracy.

[0005] QCM sensors offer advantages such as high sensitivity, non-contact detection, and rapid response, making them particularly suitable for detecting trace substances. In biosensing applications, QCMs can monitor interactions between biomolecules and biological reactions, such as the binding of proteins, antibodies, or DNA. In coagulation function testing, QCMs can be used to monitor the coagulation process in blood in real time, especially changes at the particle and molecular levels during blood clotting.

[0006] However, traditional QCM detection methods mostly rely on phase detection, which places high demands on system accuracy and hardware, and is easily affected by factors such as noise and environmental changes during the detection process. Therefore, there is currently a lack of a QCM sensor method based on amplitude change detection, which can effectively reduce the requirements for system accuracy and hardware, and provide a more stable and convenient way to monitor coagulation function. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a method and system for coagulation detection using a QCM sensor based on amplitude detection. This invention combines a QCM sensor with voltage amplitude ratio detection technology to detect the coagulation function of patients.

[0008] Unlike traditional QCM sensors that rely on high-precision phase detection, this invention designs a simple and effective voltage amplitude ratio detection system that significantly reduces the hardware requirements of the instrument while ensuring high detection accuracy. This innovative method eliminates the reliance on complex circuits and high-cost equipment in existing technologies, greatly reducing the overall system cost and improving its accessibility, making it particularly suitable for daily monitoring of patients in the clinical recovery period.

[0009] The technical solution adopted by this invention to solve the technical problem is as follows:

[0010] This invention provides a coagulation detection method using a QCM sensor based on amplitude detection, comprising the following steps:

[0011] (1) Start the DDS sweep frequency source and signal conditioning circuit, and use the signal conditioning circuit to control the DDS sweep frequency source to output a stable sweep frequency signal to the QCM sensor.

[0012] (2) When blood is dropped onto the surface of a quartz crystal, the resonant frequency of the quartz crystal will change when the blood coagulates on the surface of the quartz crystal. The QCM sensor detects the sweep frequency signal and reacts to the signal amplitude according to the change in resonant frequency.

[0013] (3) The DDS sweep frequency source gradually adjusts the sweep frequency signal frequency, and the QCM sensor monitors the signal amplitude change in real time;

[0014] (4) The amplitude detection module detects the signal amplitude in real time and feeds the signal back to the microcontroller through the signal acquisition module;

[0015] (5) Use a microcontroller to control the frequency sweep parameters to control the frequency sweep process of the DDS frequency sweep source; at the same time, the microcontroller uses the Kalman filter algorithm to optimize the received signal and outputs the measurement results to the human-machine interaction module for display and the data storage module for storage.

[0016] (7) Users can adjust system parameters through the human-computer interaction module, and the microcontroller provides feedback and controls the frequency sweeping process.

[0017] (8) The final measurement results are displayed and output through the host computer to complete the coagulation function monitoring.

[0018] Furthermore, the phenomenon that the increase in the surface mass density of the quartz crystal is proportional to the decrease in its resonant frequency is described by the Sauerbrey equation:

[0019]

[0020] in, The term is defined as the mass sensitivity of quartz crystals. ρ represents the square of the fundamental frequency (resonant frequency) of a quartz crystal. q The density of quartz crystals, v q It represents the sound wave propagation speed (shear mode velocity) of quartz crystal; by measuring the change in resonant frequency, it reflects the change in the surface quality of quartz crystal during the coagulation process.

[0021] Furthermore, the impedance formula for the equivalent circuit of the quartz crystal is:

[0022]

[0023] In the formula, Z represents the total impedance in the circuit, R represents the resistance in the circuit, j represents the imaginary unit, ω represents the angular frequency of the AC signal, L represents the inductance in the circuit, and C represents the capacitance in the circuit.

[0024] Furthermore, when the equivalent circuit of the quartz crystal is at its resonant frequency, the inductance and capacitance of the equivalent circuit cancel each other out, and the impedance of the quartz crystal decreases sharply. This results in the voltage across the quartz crystal being much greater than the voltage across the DDS sweep frequency source. This characteristic can be used to accurately measure the resonant frequency.

[0025] Furthermore, the signal conditioning circuit uses gain control and digital filtering algorithms to optimize the output signal; it uses gain control to automatically adjust the signal amplitude to ensure that it is within the optimal operating range; and it uses digital filtering algorithms to suppress noise and spurious components in the frequency signal to output a stable sweep frequency signal.

[0026] Furthermore, in step (4), an adaptive variable step size control algorithm is adopted to accurately adjust the frequency register in the DDS sweep frequency source by collecting amplitude information in real time and feeding it back to the microcontroller.

[0027] Furthermore, the amplitude discrimination module internally employs a logarithmic amplifier to convert the input signal amplitude into a logarithmic voltage signal.

[0028] This invention provides a QCM sensor-based coagulation detection system based on amplitude detection, comprising:

[0029] Cloud display module, data storage module, human-computer interaction module, microcontroller, power supply module, DDS sweep frequency source, signal conditioning circuit, QCM sensor, amplitude discrimination module and signal acquisition module;

[0030] The cloud display module is used to upload the collected experimental data to the cloud display module in real time, so that users can view the change curve of the quartz crystal resonant frequency through mobile phones, computers or other terminal devices;

[0031] The data storage module is used to locally store the collected resonant frequency data for use by the cloud display module, as well as for subsequent analysis and comparison of experimental results.

[0032] The human-computer interaction module is used to manually adjust and control system parameters to adapt to quartz crystals with different resonant frequencies; and to receive data feedback from the microcontroller.

[0033] The microcontroller is used to control the frequency sweep parameters to control the frequency sweep process of the DDS frequency sweep source; to optimize the signal sent by the signal acquisition module using the Kalman filter algorithm; and to feed back data to the human-machine interaction module.

[0034] The power supply module is used to supply power to the microcontroller, DDS sweep frequency source, QCM sensor, amplitude discrimination module and signal acquisition module;

[0035] DDS sweep frequency source is used to output a stable sweep frequency signal and to gradually adjust the frequency of the sweep frequency signal;

[0036] The signal conditioning circuit is used to amplify, filter, and process the signal output by the QCM sensor to improve signal quality and ensure that the subsequent signal acquisition module can accurately obtain the resonant frequency and amplitude information.

[0037] QCM sensors are used to monitor sweep frequency signals and react to signal amplitude changes based on resonant frequency changes, as well as to monitor signal amplitude changes in real time.

[0038] The amplitude detection module uses an internal logarithmic amplifier to detect the response at the resonant frequency and to detect the signal amplitude in real time.

[0039] The signal acquisition module is used to acquire the voltage signal of the amplitude discrimination module in real time and feed the signal back to the microcontroller.

[0040] Furthermore, the human-computer interaction module includes: a host computer display module, an LCD screen display module, a button control module, and a touch screen control module; the host computer display module is used to display the resonant frequency change curve on the mobile terminal, the LCD screen display module is used to display the resonant frequency change curve on the system, the button control module is used to adjust the parameters of the frequency sweep module, and the touch screen control module is used to switch the frequency sweep mode and reset the system.

[0041] Furthermore, the DDS sweep frequency source includes a frequency register, a phase accumulator, a waveform memory, and a digital-to-analog converter. The frequency register stores the frequency setting value of the sweep signal and controls the output frequency of the DDS sweep frequency source. The phase accumulator generates phase information and accumulates the phase value according to the frequency tuning word (FTW). The waveform memory stores standard waveform data (such as sine waves, square waves, or triangle waves). The digital-to-analog converter converts the digital signal generated by the DDS module (standard waveform data from the waveform memory) into an analog signal.

[0042] The beneficial effects of this invention are:

[0043] This invention proposes a coagulation detection method and system based on amplitude detection using a QCM sensor by establishing the relationship between load mass and signal amplitude change. When the coagulation state changes, this invention monitors the amplitude change of the QCM sensor signal, thereby reflecting the change in the resonant frequency of the quartz crystal under different coagulation functions.

[0044] This invention monitors amplitude fluctuations during the coagulation process in real time by analyzing the relationship between load mass and signal amplitude changes, thereby reflecting the resonant frequency variation curve of the quartz crystal under different coagulation functions. The system employs a high-speed DDS sweep frequency source combined with precise signal conditioning circuitry to ensure stable signal amplitude output and accurate frequency acquisition. To achieve more precise control, this invention introduces an adaptive variable step-size control algorithm to acquire and feedback amplitude information in real time, dynamically adjusting the frequency register in the DDS sweep frequency source to optimize the frequency response. A high-precision amplitude discrimination module is designed, employing advanced circuit optimization technology to overcome signal noise and amplitude distortion problems, ensuring high reliability of signal amplitude changes. To further improve data accuracy and stability, the system uses a Kalman filter algorithm to adjust the output resonant frequency data in real time, significantly improving the system's resistance to environmental interference and ensuring high accuracy and reliability of coagulation function monitoring. This invention not only overcomes the limitations of traditional methods but also has broader application prospects, particularly suitable for clinical health monitoring and telemedicine systems. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structural composition of a QCM sensor coagulation detection system based on amplitude detection provided by the present invention.

[0046] Figure 2 This is a flowchart of a coagulation detection method based on amplitude detection using a QCM sensor provided by the present invention.

[0047] Figure 3 It is the difference in amplitude of the resonant frequency.

[0048] Figure 4 This is a diagram showing the effect of Kalman filtering.

[0049] Figure 5 It is a graph showing the change in the resonant frequency curve during the blood clotting process. Detailed Implementation

[0050] The present invention will be further described in detail below with reference to the accompanying drawings.

[0051] In a first aspect, the present invention provides a QCM sensor coagulation detection system based on amplitude detection.

[0052] See Figure 1 As described above, the present invention provides a QCM sensor-based coagulation detection system based on amplitude detection, which specifically includes the following modules:

[0053] The system comprises a cloud display module, a data storage module, a human-computer interaction module, a microcontroller, a power supply module, a signal source, a QCM sensor, an amplitude discrimination module, and a signal acquisition module. The signal source mainly consists of a DDS sweep frequency source and a signal conditioning circuit. Their connections are as follows: the cloud display module is connected to the data storage module; the data storage module is connected to both the human-computer interaction module and the microcontroller; the power supply module is connected to the microcontroller, the DDS sweep frequency source, the QCM sensor, the amplitude discrimination module, and the signal acquisition module; the microcontroller is connected to the DDS sweep frequency source; the DDS sweep frequency source is connected to the QCM sensor; the QCM sensor is connected to the amplitude discrimination module; the amplitude discrimination module is connected to the signal acquisition module; and the signal acquisition module is connected to the microcontroller.

[0054] In this invention, the functions and roles of each module are as follows:

[0055] The cloud display module is mainly used to upload the collected experimental data to the cloud display module in real time, so that users can view the change curve of the quartz crystal resonant frequency through mobile phones, computers or other terminal devices.

[0056] The data storage module is mainly used for local storage of the collected resonant frequency data for use by the cloud display module, as well as for subsequent analysis and comparison of experimental results.

[0057] The human-computer interaction module is mainly used for manually adjusting and controlling system parameters to adapt to quartz crystals with different resonant frequencies; and for receiving data feedback from the microcontroller.

[0058] In this invention, the human-computer interaction module mainly includes: a host computer display module, an LCD screen display module, a button control module, and a touch screen control module; wherein, the host computer display module is mainly used to display the resonant frequency change curve on the mobile terminal, the LCD screen display module is mainly used to display the resonant frequency change curve on the system, the button control module is mainly used to adjust the parameters of the frequency sweep module, and the touch screen control module is mainly used to switch the frequency sweep mode and reset the system.

[0059] The microcontroller is mainly used to control the frequency sweep parameters to control the frequency sweep process of the DDS frequency sweep source; to optimize the signal sent by the signal acquisition module (i.e., the frequency sweep result) using the Kalman filter algorithm; and to feed back data to the human-machine interaction module.

[0060] The power supply module is mainly used to supply power to the microcontroller, DDS sweep frequency source, QCM sensor, amplitude discrimination module and signal acquisition module.

[0061] The DDS sweep frequency source is mainly used to output a stable sweep signal and to gradually adjust the frequency of the sweep signal. Additionally, the DDS sweep frequency source includes a frequency register, primarily used to store the frequency setting value of the sweep signal and control the output frequency of the DDS sweep frequency source.

[0062] The DDS sweep frequency source also includes a phase accumulator, waveform memory, and analog-to-digital converter.

[0063] The phase accumulator is mainly used to generate phase information by accumulating phase values ​​based on the frequency tuning word (FTW).

[0064] Waveform memory is mainly used to store standard waveform data (such as sine waves, square waves, or triangle waves).

[0065] Digital-to-analog converters are mainly used to convert digital signals (standard waveform data from waveform memory) generated by DDS modules into analog signals.

[0066] The signal conditioning circuit mainly uses gain control and digital filtering algorithms to optimize the output signal. Gain control automatically adjusts the signal amplitude to ensure it is within the optimal operating range, thereby improving the signal-to-noise ratio; while the digital filtering algorithm effectively suppresses noise and spurious components in the frequency signal, providing a smoother sweep signal output.

[0067] QCM sensors are mainly used to monitor sweep frequency signals and react to signal amplitude changes based on resonant frequency changes, as well as to monitor signal amplitude changes in real time.

[0068] In this invention, a series resonant circuit is designed in the QCM sensor. Through the series resonant circuit, when the frequency of the DDS sweep source is the resonant frequency, the voltage across the DDS sweep source is much smaller than the voltage across the quartz crystal.

[0069] The amplitude discrimination module uses a logarithmic amplifier to detect the response at the resonant frequency and to detect the signal amplitude in real time.

[0070] The signal acquisition module is mainly used to acquire the voltage signal of the amplitude discrimination module in real time and feed the signal back to the microcontroller.

[0071] The present invention provides a QCM sensor coagulation detection system based on amplitude detection, the specific working process of which is as follows:

[0072] (1) The DDS sweep frequency source starts working and outputs a sweep frequency signal to the QCM sensor.

[0073] (2) When blood is dropped onto the surface of a quartz crystal, the resonant frequency of the quartz crystal will change when the blood coagulates on the surface of the quartz crystal. The QCM sensor detects the sweep frequency signal and reacts to the signal amplitude according to the change in resonant frequency.

[0074] (3) The DDS sweep frequency source gradually adjusts the sweep frequency signal frequency, and the QCM sensor monitors the signal amplitude change in real time.

[0075] (4) The amplitude detection module detects the signal amplitude in real time and feeds the signal back to the microcontroller through the signal acquisition module using an adaptive variable step size control algorithm.

[0076] (5) The microcontroller controls the frequency sweep parameters to control the frequency sweep process of the DDS frequency sweep source; at the same time, the microcontroller uses the Kalman filter algorithm to optimize the received signal and outputs the measurement results to the human-machine interaction module for display and the data storage module for storage; in this invention, the output data is adjusted in real time by the Kalman filter algorithm to reduce the measurement error and improve the accuracy and reliability of the detection results.

[0077] (7) Users can adjust system parameters through the human-computer interaction module, and the microcontroller will provide feedback and control the frequency sweeping process.

[0078] (8) The final measurement results are displayed and output through the host computer to complete the coagulation function monitoring.

[0079] In this invention, the microcontroller may specifically be an STM32 chip, but is not limited to this.

[0080] The core technologies of this invention include the following aspects:

[0081] 1) Signal monitoring based on amplitude changes;

[0082] This invention accurately captures changes in coagulation state by detecting variations in signal amplitude. When the coagulation state changes, minute changes in blood composition lead to variations in the adhesion mass on the surface of the QCM sensor, thereby causing changes in the resonant frequency. By monitoring these amplitude changes, different states of coagulation function can be effectively reflected.

[0083] 2) Signal acquisition and amplitude discrimination circuit design;

[0084] Based on the principle of amplitude measurement, a high-efficiency signal acquisition module and amplitude discrimination module were designed. Through the design of signal processing and amplitude discrimination circuits, the amplitude changes of the QCM sensor output signal can be accurately extracted, amplified, and processed for further analysis of coagulation status.

[0085] 3) Kalman filter optimization;

[0086] To improve data accuracy, this invention introduces a Kalman filter algorithm into the microcontroller. Kalman filtering effectively eliminates noise and interference, resulting in more accurate and reliable displayed coagulation function data.

[0087] 4) High-speed DDS sweep frequency source drive;

[0088] This invention employs a high-speed DDS (Direct Digital Frequency Synthesizer) sweep frequency source as the signal driving circuit, ensuring that the system can provide accurate and stable frequency output to meet the high frequency requirements of QCM sensors. The application of the high-speed DDS sweep frequency source effectively improves the system's response speed and stability, ensuring reliability in clinical monitoring.

[0089] 5) Data interaction between the user end and the hospital end:

[0090] The human-computer interaction module can be used to send data from the user end to the hospital end via wireless communication, and the hospital end can analyze and take measures based on this data in real time.

[0091] This invention not only enables real-time monitoring of coagulation function at a lower cost, but also overcomes the reliance of traditional QCM sensors on high-precision phase detection through amplitude change monitoring, thus having broader application prospects. By combining Kalman filtering with a high-speed DDS sweep frequency source, this invention also significantly improves data accuracy and system performance, making it suitable for efficient detection of coagulation function in home or mobile medical devices.

[0092] Secondly, the present invention provides a coagulation detection method based on amplitude detection using a QCM sensor, which is mainly implemented by the coagulation detection system based on amplitude detection provided in the first aspect of the present invention.

[0093] See Figure 2The present invention provides a coagulation detection method based on amplitude detection using a QCM sensor, which specifically involves the following innovations:

[0094] (1) During the coagulation process, when blood coagulates on the surface of the quartz crystal, the signal amplitude change during the coagulation process is monitored according to the relationship between the load mass and the signal amplitude response, so as to reflect the resonant frequency change curve of the quartz crystal under different coagulation functions, and the corresponding signal acquisition module is designed based on the amplitude measurement principle.

[0095] It should be noted that Sauerbrey proposed a linear relationship between the resonant frequency of a quartz crystal and the mass deposited on its surface, revealing that the increase in surface mass density of a quartz crystal is proportional to the decrease in its resonant frequency. This phenomenon can be described by the Sauerbrey equation, the specific mathematical expression of which is shown below:

[0096]

[0097] In the formula, The term is defined as the mass sensitivity of quartz crystals, where, ρ represents the square of the fundamental frequency (resonant frequency) of a quartz crystal. q The density of quartz crystals, v q This represents the acoustic wave propagation speed (shear mode velocity) of a quartz crystal; taking a 5MHz AT-cut quartz crystal as an example, the areal density is increased to 17.7 ng / cm³. 2 The presence of certain substances will cause a 1 Hz frequency shift. The most significant contribution of the Sauerbrey equation is that it characterizes the shift in resonant frequency as being caused by an increase in the surface mass of the quartz crystal, and that this shift is linear in the case of minute increments.

[0098] The impedance formula for the equivalent circuit of a quartz crystal is shown below:

[0099]

[0100] In the formula, Z represents the total impedance in the circuit, R represents the resistance in the circuit, j represents the imaginary unit, ω represents the angular frequency of the AC signal, L represents the inductance in the circuit, and C represents the capacitance in the circuit.

[0101] When the equivalent circuit of the quartz crystal is at its resonant frequency, the inductance and capacitance of the equivalent circuit cancel each other out, leaving only the resistance. To establish a relationship between the resonant frequency of the quartz crystal and the amplitude difference of the signal, this invention designs a series resonant circuit. This ensures that when the frequency of the DDS sweep source is at the resonant frequency, the voltage across the DDS sweep source is significantly lower than the voltage across the quartz crystal. By adjusting the resistance value in the series resonant circuit, a higher voltage is maintained across the quartz crystal at the resonant point, thus creating a significant difference between the resonant frequency of the quartz crystal and the amplitude change of the signal. This design allows for precise detection of changes in the resonant frequency of the quartz crystal by monitoring amplitude variations, effectively reflecting frequency fluctuations during the coagulation process.

[0102] The response of the quartz crystal at the resonant frequency is as follows: Figure 3 As shown, two sinusoidal signals with different amplitudes are used. The sinusoidal signal with an amplitude of 1 represents the voltage across the signal source, and the sinusoidal signal with an amplitude of 10000 represents the voltage across the quartz crystal. At the resonant frequency, the voltage across the quartz crystal will be much greater than the voltage across the signal source, and the voltage amplitude difference is very large. Therefore, this phenomenon can be used to detect the resonant frequency.

[0103] This invention uses amplitude difference to detect resonant frequency instead of traditional phase detection technology, thus avoiding the complexity of high-precision phase detection and improving detection efficiency.

[0104] (2) The signal source section adopts a high-speed DDS (direct digital frequency synthesis) sweep frequency source. By adding a signal conditioning circuit, the amplitude of the input signal is stabilized. The signal conditioning circuit of the signal source generation and frequency acquisition ensures the output of the drive signal is stable, so as to achieve higher precision frequency control.

[0105] This invention utilizes direct digital frequency synthesis (DDS) technology, starting from the phase perspective, to find the corresponding sampled value in the waveform memory, and then obtain the desired signal through an analog-to-digital converter (ADC) and filters. Its output signal boasts extremely high frequency resolution and frequency conversion rate advantages. The DDS sweep frequency source can provide a stable and adjustable output frequency, suitable for high-resolution resonant frequency detection requirements. Through a high-speed DDS sweep frequency source, the system can precisely adjust the frequency, thereby improving the working accuracy of the QCM sensor.

[0106] It should be noted that although the DDS sweep frequency source can provide high-precision frequency output, its unique internal structure inevitably results in noise and spurious components in the output signal, mainly stemming from errors caused by phase truncation, amplitude quantization, and DAC (digital-to-analog converter) conversion. These noise and spurious components can affect signal stability, thus impacting the accuracy of frequency detection. To address this issue, this invention employs gain control and digital filtering algorithms to optimize the output signal. Gain control automatically adjusts the signal amplitude to ensure it operates within its optimal range, thereby improving the signal-to-noise ratio; while the digital filtering algorithm effectively suppresses noise and spurious components in the frequency signal, providing a smoother sweep signal output. The combination of these two methods further enhances the system's detection accuracy and reliability, effectively preventing noise from affecting system performance.

[0107] (3) The present invention adopts an adaptive variable step size control algorithm to collect amplitude information in real time and feed it back to the microcontroller, thereby adjusting the frequency register in the DDS sweep frequency source through the microcontroller to achieve precise control.

[0108] It should be noted that at the DDS sweep source, this invention employs an adaptive variable step size control algorithm. This algorithm collects amplitude information in real time and feeds it back to the microcontroller, thereby precisely adjusting the frequency register in the DDS sweep source. This invention dynamically adjusts the frequency step value based on actual conditions using the adaptive variable step size control algorithm to optimize the frequency search process. Specifically, when the frequency approaches the resonant point, the step size automatically decreases to improve the accuracy of frequency adjustment; conversely, when the frequency is far from the resonant point, the step size increases to accelerate the adjustment speed. This variable step size control strategy not only improves the response speed of frequency adjustment but also ensures the accuracy of the frequency locking process, thus achieving more precise and efficient frequency control.

[0109] (4) An amplitude discrimination module was designed to accurately extract the amplitude information of the signal. This amplitude discrimination module solves the problems of signal noise and amplitude distortion by optimizing the circuit design, and ensures the accurate detection of amplitude changes.

[0110] It should be noted that by carefully designing the circuit and composition of the amplitude discrimination module, the amplitude information of the signal can be extracted efficiently and accurately. The module internally employs a logarithmic amplifier, which converts the input signal amplitude into a logarithmic voltage signal. The function of the logarithmic amplifier is to convert the amplitude change of the input signal into a voltage change proportional to the logarithm of the signal amplitude, significantly reducing the influence of signal noise and amplitude distortion, thus improving the accuracy of amplitude measurement. Through appropriate amplification and filtering of the signal, the amplitude discrimination module can effectively suppress external interference, improve signal quality, and thus accurately capture minute changes in amplitude. Furthermore, the amplitude discrimination module can adapt to signal fluctuations under different operating environments, further improving the stability and reliability of the system and ensuring accurate detection of amplitude changes.

[0111] (5) The output resonant frequency is adjusted in real time by Kalman filtering to make the system unaffected by the environment or other interference factors, so as to achieve more reliable coagulation function monitoring.

[0112] It should be noted that in this invention, the Kalman filter algorithm is used to process the output resonant frequency data in real time to reduce the impact of environmental noise or other interference factors that may affect the system during the detection process. By dynamically estimating and predicting the frequency data, the Kalman filter can effectively smooth the measurement data, reduce errors caused by sensor noise or external disturbances, and thus provide more accurate and stable detection results. This Kalman filter process not only improves the real-time responsiveness of the frequency data but also enhances the robustness of the system, ensuring the reliability and accuracy of coagulation function monitoring under various operating conditions.

[0113] Among them, the Kalman filter effect is as follows: Figure 4 As shown, Kalman filtering effectively smooths the original data. The original data (represented by black dots) in the graph shows the acquired frequency signals. It can be observed that the original data contains some noise, manifested as high-frequency small-amplitude oscillations and deviations. This noise may originate from the instability of the measuring equipment, environmental interference, or internal system errors. The Kalman-filtered data (represented by black crosses) in the graph shows the frequency signals after Kalman filtering. The Kalman-filtered data is smoother than the original data, significantly reducing noise interference. This demonstrates that Kalman filtering can effectively suppress random noise while preserving the main trend of the signal.

[0114] In this invention, the final obtained coagulation process resonant frequency curve change is as follows: Figure 5As shown, a 13MHz quartz crystal chip was used to detect prothrombin time (PT). Coagulation control material (plasma) was added at time T1. At time T2, after the quartz crystal resonant frequency stabilized, the PT reagent was added to initiate the coagulation reaction. The plasma slowly coagulated, causing the quartz crystal resonant frequency to decrease. Time T3 marked the end of the reaction. The frequency change curve reflects the coagulation reaction process.

[0115] This invention discloses a coagulation detection method using a QCM sensor based on amplitude detection, which monitors coagulation by detecting changes in signal amplitude. Compared to traditional phase detection-based methods, amplitude detection effectively overcomes the sensitivity and accuracy issues inherent in phase detection. Phase detection methods may be affected by environmental noise, signal attenuation, and other factors under certain conditions, leading to decreased detection accuracy. In contrast, amplitude detection methods, by directly analyzing changes in signal intensity, provide more stable and reliable measurement results. Therefore, the amplitude detection-based QCM sensor can offer higher performance in practical applications, especially in dynamically monitoring blood coagulation, accurately reflecting the coagulation process in real time and providing more precise data support for medical monitoring.

[0116] The present invention provides a QCM sensor coagulation detection method and system based on amplitude detection, which can be implemented in the form of software functional units and stored in a computer-readable storage medium.

[0117] The computer-readable storage media mentioned above include, but are not limited to, USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks or optical disks, and other media that can store program code.

[0118] Based on the above understanding, the technical solution of this invention, or the part that contributes to the prior art, can be embodied in the form of a software product. The technical solution of this invention is implemented as a software product on the ZYNQ platform. The ZYNQ platform integrates an ARM processor and an FPGA (Field-Programmable Gate Array), enabling efficient implementation of complex signal processing functions through the combination of hardware and software. The ZYNQ platform can not only execute advanced algorithms such as control logic, data acquisition, and Kalman filtering, but also utilize its FPGA portion to accelerate tasks such as signal acquisition, processing, and parallel computing.

[0119] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for coagulation detection using a QCM sensor based on amplitude detection, characterized in that, Includes the following steps: (1) Start the DDS sweep frequency source and signal conditioning circuit, and use the signal conditioning circuit to control the DDS sweep frequency source to output a stable sweep frequency signal to the QCM sensor; The signal conditioning circuit uses gain control and digital filtering algorithms to optimize the output signal; gain control automatically adjusts the signal amplitude to ensure it is within the optimal operating range; and digital filtering algorithms suppress noise and spurious components in the frequency signal to output a stable sweep frequency signal. (2) When blood is dropped onto the surface of a quartz crystal, the resonant frequency of the quartz crystal will change when the blood coagulates on the surface of the quartz crystal. The QCM sensor detects the sweep frequency signal and reacts to the signal amplitude according to the change in resonant frequency. (3) The DDS sweep frequency source gradually adjusts the sweep frequency signal frequency, and the QCM sensor monitors the signal amplitude change in real time; (4) The amplitude detection module detects the signal amplitude in real time and feeds the signal back to the microcontroller through the signal acquisition module; An adaptive variable step size control algorithm is adopted to precisely adjust the frequency register in the DDS sweep frequency source by collecting amplitude information in real time and feeding it back to the microcontroller. The amplitude discrimination module uses a logarithmic amplifier to convert the input signal amplitude into a logarithmic voltage signal. (5) Use a microcontroller to control the frequency sweep parameters to control the frequency sweep process of the DDS frequency sweep source; at the same time, the microcontroller uses the Kalman filter algorithm to optimize the received signal and outputs the measurement results to the human-machine interaction module for display and the data storage module for storage. (6) The user adjusts the system parameters through the human-computer interaction module, and the microcontroller provides feedback and controls the frequency sweeping process; (7) The final measurement results are displayed and output through the host computer to complete the coagulation function monitoring; The phenomenon that the increase in surface mass density of the quartz crystal is proportional to the decrease in its resonant frequency is described by the Sauerbrey equation: ； in, The term is defined as the mass sensitivity of quartz crystals. The square of the resonant frequency of a quartz crystal is represented by . The density of quartz crystals is indicated. It represents the speed of sound propagation in quartz crystals; by measuring changes in the resonant frequency, it reflects changes in the surface quality of quartz crystals during the coagulation process. The impedance formula for the equivalent circuit of the quartz crystal is: ； In the formula, Z represents the total impedance in the circuit, R represents the resistance in the circuit, and j represents the imaginary unit. L represents the angular frequency of the AC signal, C represents the inductance value in the circuit, and C represents the capacitance value in the circuit. When the equivalent circuit of a quartz crystal is at its resonant frequency, the inductance and capacitance of the equivalent circuit cancel each other out, and the impedance of the quartz crystal decreases sharply. This results in the voltage across the quartz crystal being much greater than the voltage across the DDS sweep frequency source. This characteristic is used to accurately measure the resonant frequency.

2. A QCM sensor coagulation detection system based on amplitude detection, applied to the QCM sensor coagulation detection method based on amplitude detection as described in claim 1, characterized in that, include: Cloud display module, data storage module, human-computer interaction module, microcontroller, power supply module, DDS sweep frequency source, signal conditioning circuit, QCM sensor, amplitude discrimination module and signal acquisition module; The cloud display module is used to upload the collected experimental data to the cloud display module in real time, so that users can view the change curve of the quartz crystal resonant frequency through mobile phones, computers or other terminal devices; The data storage module is used to locally store the collected resonant frequency data for use by the cloud display module, as well as for subsequent analysis and comparison of experimental results. The human-computer interaction module is used to manually adjust and control system parameters to adapt to quartz crystals with different resonant frequencies; And receive data from the microcontroller; The microcontroller is used to control the frequency sweep parameters in order to control the frequency sweep process of the DDS frequency sweep source; And it is used to optimize the signals sent by the signal acquisition module using the Kalman filtering algorithm; And for feeding back data to the human-computer interaction module; The power supply module is used to supply power to the microcontroller, DDS sweep frequency source, QCM sensor, amplitude discrimination module and signal acquisition module; DDS sweep frequency source is used to output a stable sweep frequency signal and to gradually adjust the frequency of the sweep frequency signal; The signal conditioning circuit is used to amplify and filter the signal output by the QCM sensor to improve signal quality and ensure that the subsequent signal acquisition module can accurately obtain the resonant frequency and amplitude information. QCM sensors are used to monitor sweep frequency signals and react to signal amplitude changes based on resonant frequency changes, as well as to monitor signal amplitude changes in real time. The amplitude detection module uses an internal logarithmic amplifier to detect the response at the resonant frequency and to detect the signal amplitude in real time. The signal acquisition module is used to acquire the voltage signal of the amplitude discrimination module in real time and feed the signal back to the microcontroller.

3. The QCM sensor coagulation detection system based on amplitude detection according to claim 2, characterized in that, The human-computer interaction module includes: a host computer display module, an LCD screen display module, a button control module, and a touch screen control module; the host computer display module is used to display the resonant frequency change curve on the mobile terminal, the LCD screen display module is used to display the resonant frequency change curve on the system, the button control module is used to adjust the DDS sweep frequency source parameters, and the touch screen control module is used to switch the sweep frequency mode and reset the system.

4. The QCM sensor coagulation detection system based on amplitude detection according to claim 2, characterized in that, The DDS sweep frequency source includes a frequency register, a phase accumulator, a waveform memory, and a digital-to-analog converter. The frequency register stores the frequency setting value of the sweep signal and controls the output frequency of the DDS sweep frequency source. The phase accumulator generates phase information and accumulates the phase value according to the frequency control word. The waveform memory stores standard waveform data. The digital-to-analog converter converts the digital signal generated by the DDS sweep frequency source into an analog signal.

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