A Breath-Triggered Microgrid Nebulizer Based on a Thermocouple Sensor

Abstract

This invention relates to the field of micro-mesh nebulizer technology and discloses a breath-triggered micro-mesh nebulizer based on thermocouple sensors. The device includes a second and third port on a three-way tube. A breath sensing module has a differential sensor array on a flexible circuit board, with each sensing unit including at least a thermocouple sensor. The nebulization module integrates an impedance measurement circuit and a drive circuit on the flexible circuit board, multiplexing the micro-mesh transducer to sense its own state. The controller weights and fuses the signals from the sensing units in the differential sensor array and predicts the inspiratory initiation time. At the end of expiration, a pre-trigger command is issued to drive the transducer to pre-charge the nebulized medication at low power. Simultaneously, impedance characteristics are collected to obtain the micro-mesh efficiency value. During the inspiratory phase, the drive power is compensated and corrected according to the real-time flow rate ratio and efficiency value. During the expiratory phase, a reverse pulse is applied to clean the micro-mesh and the effect is recorded to predict subsequent cleaning timing. This achieves closed-loop control with predictive triggering of the breath phase, staged scheduling, and efficiency self-calibration.

Description

Technical Field

[0001] This invention relates to the field of micro-mesh atomizer technology, specifically to a breath-triggered micro-mesh atomizer based on a thermocouple sensor. Background Technology

[0002] Nebulized inhalation is an important treatment method for mechanically ventilated patients. Existing nebulizers typically consist of a nebulization module, a controller, and connecting tubing. They are used in conjunction with the ventilator circuit to convert liquid medication into a nebulized drug solution, which is then delivered to the patient's lungs via airflow.

[0003] In terms of trigger sensing, conventional nebulizers generally have inherent trigger delays and are easily affected by fluctuations in body and ambient temperatures, leading to false triggers. This causes the nebulization timing to deviate from the actual inspiratory phase, resulting in some medication being wasted during the expiratory phase. In terms of drive control, existing nebulizers only implement simple on / off switching, continuously nebulizing at a fixed power throughout the inspiratory phase. When the flow rate decreases at the end of the inspiratory phase, the concentration of nebulized medication rises sharply, resulting in uneven deposition in the lungs and a low effective deep lung deposition rate. At the same time, drug residues gradually deposit and crystallize on the walls of the micro-mesh, leading to a reduction in the effective pore size and a continuous decrease in nebulization efficiency. Existing devices have neither the ability to sense this nor a dose compensation mechanism, causing the actual delivered dose to be systematically lower as the usage time increases.

[0004] Therefore, with significant defects in the three aspects of trigger sensing, drive control, and microgrid maintenance, the actual dose of nebulized medication received by the patient with each breath cannot be consistent with the prescription target dose, making it difficult to meet the clinical need for precise drug delivery. Summary of the Invention

[0005] This invention provides a respiratory-triggered microgrid nebulizer based on a thermocouple sensor to solve the problem of poor drug delivery accuracy caused by errors between the nebulized drug dose obtained by the patient with each breath and the target dose.

[0006] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0007] In the first aspect, a breathing-triggered microgrid nebulizer based on a thermocouple sensor includes a three-way tube, a breathing sensing module, a nebulization module, and a controller;

[0008] The three-way tube has a first port, a second port and a third port. The first port is used to connect to the patient's airway, the third port is used to connect to the ventilator circuit, and the second port is connected to the nebulizer module.

[0009] The atomization module includes a micro-mesh transducer disposed at the end of the second port, a micro-mesh atomizing plate disposed within the micro-mesh transducer, and a liquid medicine cup disposed above the micro-mesh transducer.

[0010] The breathing sensing module includes a flexible circuit board and a differential sensing array disposed on the flexible circuit board. The differential sensing array includes a plurality of sensing units spaced apart along the airflow channel direction of the three-way tube. Each sensing unit includes at least a thermocouple sensor.

[0011] The atomization module includes a microgrid transducer and a driving circuit integrated on the flexible circuit board. The driving circuit is provided with an impedance measurement circuit, which is electrically connected to the microgrid transducer.

[0012] The controller is electrically connected to the respiratory sensing module and the nebulization module respectively, and is used to perform weighted fusion processing on the signals output by the sensing units in the differential sensing array to obtain the patient's respiratory phase signal;

[0013] The respiratory phase signal of the current respiratory cycle is compared and analyzed with the respiratory phase signal of the historical respiratory cycles to obtain a respiratory frequency information set. The start time of the next inhalation is predicted based on the respiratory frequency information set, and a pre-trigger command is sent to the nebulization module at the end of the current expiratory phase.

[0014] In response to the pre-trigger command, the microgrid transducer is driven in a low-power pulse mode to pre-charge the inner cavity of the three-way tube with atomized medicine;

[0015] The microgrid efficiency value is obtained by fusing the resonant frequency shift, impedance magnitude change, and phase angle drift of the microgrid transducer collected by the impedance measurement circuit.

[0016] During the inspiratory phase, the real-time inspiratory flow rate is detected, the transducer drive power is proportionally adjusted to the real-time inspiratory flow rate, and the microgrid efficiency value is incorporated into the compensation correction of the drive power to obtain the corrected drive power, so that the nebulized drug dose delivered with each breath matches the prescription target amount.

[0017] Furthermore, the controller is electrically connected to both the respiratory sensing module and the nebulization module, and is used to perform weighted fusion processing on the signals output by the sensing units in the differential sensing array to obtain the patient's respiratory phase signal. This also includes:

[0018] During the exhalation phase, the drive phase of the transducer is reversed, and a reverse drive pulse sequence is applied to the micro-mesh transducer, causing the micro-mesh to vibrate in the opposite direction to the transducer vibration when the nebulized drug is generated. This peels off the deposits on the micro-mesh pore wall towards the drug cup side and restores the effective pore size of the micro-mesh.

[0019] After the reverse drive pulse is executed, the resonant frequency shift, impedance magnitude change and phase angle drift of the microgrid transducer are collected again through the impedance measurement circuit to obtain the microgrid efficiency value after cleaning. The microgrid efficiency values ​​before and after cleaning are compared and recorded to predict the timing of subsequent cleaning.

[0020] Furthermore, the controller is electrically connected to both the respiratory sensing module and the nebulization module, and is used to perform weighted fusion processing on the signals output by the sensing units in the differential sensing array to obtain the patient's respiratory phase signal. This also includes:

[0021] The low-frequency modulation component generated by airflow modulation in the output signal of the impedance measurement circuit is extracted, and the low-frequency modulation component is compared and verified with the signal of the thermocouple sensor in the differential sensing array. The respiratory phase signal is cross-verified to obtain the verified respiratory phase signal.

[0022] Furthermore, the sensing units in the differential sensing array also include a humidity sensor and a carbon dioxide sensor;

[0023] The arrival time of the signal of the sensing unit in the differential sensing array in the direction of the airflow channel is detected. The time difference of signal arrival between the humidity sensor and the carbon dioxide sensor and between the humidity sensor and the thermocouple sensor is extracted to obtain the airflow time gradient. The airflow time gradient and the weighted fusion processing result are used together to predict the inhalation start time.

[0024] Furthermore, the impedance measurement circuit and the driving circuit reuse the traces on the flexible circuit board; during the low-power pulse drive of the microgrid transducer to complete the pre-charging of the atomized drug solution, the impedance measurement circuit simultaneously collects the resonant frequency shift, impedance magnitude change and phase angle drift of the transducer under the low-power pulse excitation to obtain the microgrid efficiency value.

[0025] Furthermore, using the airflow temporal gradient and the weighted fusion processing result together to predict the inhalation initiation time also includes:

[0026] When performing weighted fusion processing on the signals output by the sensor units in the differential sensor array, the historical misclassification rates of the sensor units in the differential sensor array are statistically analyzed. The weights corresponding to sensor units with lower misclassification rates are set to larger values, and the weights corresponding to sensor units with higher misclassification rates are set to smaller values. The weights of the sensor units in the differential sensor array are dynamically adjusted. The adjusted weights are then weighted and summed with the corresponding sensor unit signals to obtain the comprehensive respiratory phase signal. The comprehensive signal is then compared with a preset inspiratory threshold to obtain the respiratory phase signal.

[0027] Furthermore, the step of comparing and analyzing the respiratory phase signal of the current respiratory cycle with the respiratory phase signal of historical respiratory cycles to obtain a respiratory frequency information set, predicting the start time of the next inhalation based on the respiratory frequency information set, and issuing a pre-trigger command to the nebulization module at the end of the current expiratory phase also includes:

[0028] The controller stores the inspiratory start times of the previous N respiratory cycles and calculates the moving average of the N inspiratory start times to obtain the predicted inspiratory start time of the next cycle. The controller adaptively adjusts the value of N according to the fluctuation of the patient's respiratory rate, taking a larger value when the respiratory rate is stable and a smaller value when the respiratory rate fluctuates greatly. A pre-trigger command is sent to the nebulization module before the predicted time, and the advance amount is adaptively adjusted according to the patient's current respiratory rhythm.

[0029] Furthermore, the step of responding to the pre-trigger command by driving the microgrid transducer in a low-power pulse mode to pre-charge the atomized drug solution into the inner cavity of the three-way tube also includes:

[0030] During the inspiratory phase, the controller uses the difference between the prescribed target dose and the dose already delivered during the pre-filling phase of the nebulized drug solution as the target dose to be supplemented during the inspiratory phase. The transducer drive power is set to be directly proportional to the real-time inspiratory flow rate, and the drive power is set to be inversely proportional to the microgrid efficiency value. When the microgrid efficiency value decreases, the drive power is increased proportionally to ensure that the total amount of nebulized drug solution delivered during the inspiratory phase matches the target dose.

[0031] Furthermore, the process of fusing the microgrid transducer resonant frequency shift, impedance magnitude change, and phase angle drift acquired by the impedance measurement circuit to obtain the microgrid efficiency value also includes:

[0032] The controller calculates the difference in microgrid efficiency values ​​before and after cleaning to obtain the efficiency recovery amount for a single cleaning cycle; it also statistically analyzes the time intervals during which the efficiency value drops to the cleaning trigger threshold before each cleaning cycle to obtain the efficiency decay time pattern; and it comprehensively analyzes the cleaning efficiency recovery amount and the efficiency decay time pattern to predict the timing of subsequent cleaning triggers and obtain the adaptive cleaning cycle.

[0033] Furthermore, the controller includes:

[0034] The sensing fusion unit is used to acquire signals from the sensing units in the differential sensing array, perform weighted fusion processing on the acquired multi-channel signals, and obtain the patient's respiratory phase signal.

[0035] The phase prediction unit is used to periodically store the respiratory phase signal output by the perception fusion unit, compare and analyze the current and historical respiratory cycle data, predict the start time of the next inhalation, and generate a pre-trigger command at the end of the expiratory phase.

[0036] The drive scheduling unit is used to receive the pre-trigger command from the phase prediction unit, drive the transducer in a low-power pulse mode at the end of expiration to complete the pre-filling of the nebulized drug solution; during the inspiratory phase, the real-time inspiratory flow rate is detected, and the drive power is proportionally adjusted to the inspiratory flow rate to obtain the adjusted drive power.

[0037] The efficiency compensation unit is used to fuse the resonant frequency offset, impedance magnitude change and phase angle drift collected by the impedance measurement circuit to obtain the microgrid efficiency value, and input the microgrid efficiency value into the drive scheduling unit to compensate and correct the drive power to obtain the corrected drive power.

[0038] The cleaning management unit is used to apply a reverse drive pulse to the transducer during the expiratory phase to peel off the deposits on the micromesh wall towards the drug cup side, compare and record the micromesh efficiency values ​​before and after cleaning, and predict the timing of subsequent cleaning triggers.

[0039] The above-described solution of the present invention has at least the following beneficial effects:

[0040] By employing a differential sensor array on a flexible circuit board to weightedly fuse signals from multiple sensor units and predict the inspiratory initiation time, the transducer is pre-triggered with a low-power pulse at the end of expiration to pre-charge the nebulized medication while simultaneously acquiring the transducer impedance characteristics to obtain the microgrid efficiency value. Throughout the inspiratory phase, the drive power is compensated and corrected according to the real-time flow ratio and combined with the efficiency value. A reverse pulse is applied during the expiratory phase to complete the microgrid self-cleaning. This overcomes the problems of existing nebulizers, such as trigger delay leading to misjudgment, uneven nebulization concentration at constant power, and imperceptible and uncompensated microgrid efficiency decay. As a result, the technical effect of achieving a dose of nebulized medication actually obtained by the patient with each breath matching the prescription target dose is achieved. Attached Figure Description

[0041] Figure 1 A perspective view of a breathing-triggered micro-mesh nebulizer provided in an embodiment of the present invention;

[0042] Figure 2 This is a cross-sectional plan view of the breathing-triggered micro-mesh nebulizer provided in an embodiment of the present invention;

[0043] Figure 3 This is a plan view of the end of the breathing sensing module provided in an embodiment of the present invention;

[0044] Figure 4 This is a schematic diagram of the three-dimensional structure of the flexible circuit board provided in an embodiment of the present invention;

[0045] Figure 5 A perspective view of a microgrid transducer provided in an embodiment of the present invention;

[0046] Figure 6 A controller unit diagram provided for an embodiment of the present invention;

[0047] Figure 7 Pipeline connection diagram provided for embodiments of the present invention;

[0048] Figure 8This is an overall circuit connection block diagram provided for an embodiment of the present invention;

[0049] Figure 9 A schematic diagram of a drive and impedance measurement multiplexing circuit provided in an embodiment of the present invention;

[0050] Figure 10 The schematic diagram of the thermocouple differential sensor array signal conditioning circuit provided in the embodiment of the present invention.

[0051] Explanation of reference numerals in the attached figures:

[0052] 1. Breathing sensor module; 2. Three-way tube; 3. Microgrid transducer; 4. Medicine cup; 5. Controller; 6. Flexible circuit board; 7. Carbon dioxide sensor; 8. Humidity sensor; 9. Thermocouple sensor; 10. Microgrid atomizing sheet. Detailed Implementation

[0053] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0054] like Figures 1 to 8 As shown, an embodiment of the present invention, a respiratory-triggered microgrid nebulizer based on a thermocouple sensor, includes a three-way tube 2, a respiratory sensing module 1, a nebulization module, and a controller 5. Each module is connected to the controller 5 via connecting wires. The three-way tube 2 has a first port, a second port, and a third port. The first port is connected to the patient's airway (endotracheal tube or mask), the third port is connected to the ventilator circuit, and the second port is connected to the nebulization module. The nebulization module has a medication cup 4 connected to it, allowing gas to pass through in both inhalation and exhalation directions. The angle between the second and third ports is set to 107.5°. This angle allows the nebulized medication particles generated at the second port to be more effectively carried into the first port along the airflow direction, improving the lung deposition rate.

[0055] In one embodiment of the present invention, a breathing sensing module 1 includes a flexible circuit board 6 and a differential sensing array disposed on the flexible circuit board 6. The differential sensing array includes multiple sensing units longitudinally spaced along the airflow channel direction of the three-way pipe 2, and each sensing unit includes at least a thermocouple sensor 9. The flexible circuit board 6 has bendable physical properties and can be bent and fitted along the curved surface of the three-way pipe 2, so that the sensing units in the differential sensing array form a three-dimensional differential pickup structure in space.

[0056] In this embodiment, during application, the operator can connect the tubing connected to the humidifier and the liquid collector to the end of the breathing sensor module 1 away from the three-way tube 2, then connect the mask to the first port of the three-way tube 2, inject the medicine into the medicine cup 4, then cover the mask over the patient's mouth and nose, and operate the controller 5 to start the micro-mesh nebulizer. Thus, with the cooperation of the breathing sensor module 1, the micro-mesh transducer 3 and the micro-mesh nebulizer 10, the medicine is atomized and discharged into the three-way tube 2, and inhaled by the patient.

[0057] In another embodiment, the sensing units in the differential sensing array also include a humidity sensor 8 and a carbon dioxide sensor 7, which are deployed together with the thermocouple sensor 9 at different locations on the flexible circuit board 6 to form a multimodal differential sensing array.

[0058] The arrival time of the signal from the sensing unit in the differential sensing array in the direction of the airflow channel. , ... The detection process extracts the signal arrival time difference between adjacent sensing units. The airflow time gradient vector is obtained. At the end of expiration, the airflow timing gradient The characteristic of direction reversal appears, that is The value changes from an increasing trend near the patient's airway to a decreasing trend. Based on this, the controller 5 helps to determine the phase transition time from expiration to inspiration. It is used together with the weighted fusion signal to predict the inspiratory initiation time, thereby improving the prediction accuracy.

[0059] In one embodiment of the present invention, the atomization module includes a micro-mesh transducer 3 and a driving circuit integrated on a flexible circuit board 6. The driving circuit includes an impedance measurement circuit electrically connected to the micro-mesh transducer 3. A micro-mesh atomizing plate 10 is disposed within the micro-mesh transducer 3. The lower end of the medicine cup 4 is connected to the micro-mesh atomizing plate 10 via the micro-mesh transducer 3. When the micro-mesh pores are blocked by drug residue, the piezoelectric equivalent circuit parameters of the micro-mesh transducer 3 change; specifically, the resonant frequency... Low-frequency drift, impedance magnitude Elevation, Phase Angle The offset, all three parameters can be acquired non-invasively using an impedance measurement circuit under low-power pulse excitation.

[0060] The drive circuit and impedance measurement circuit share the same traces on the flexible circuit board 6, eliminating the need for an additional independent sensor. The low-frequency loss characteristics of the flexible circuit board 6 ensure that the impedance measurement signal is not distorted during transmission within the board.

[0061] In one embodiment of the present invention, the controller 5 outputs signals to each of the n sensing units in the differential sensing array. Weighted fusion processing is performed to obtain the respiratory phase composite signal. ,

[0062]

[0063] in, Weight The weighting is dynamically adjusted based on the historical misclassification rate of the sensing units in the differential sensing array: sensing units with lower misclassification rates are assigned larger weights, while those with higher misclassification rates are assigned smaller weights. This ensures that sensing units more susceptible to interference from body temperature or ambient temperature fluctuations receive a better overall signal. The contribution of a single sensor is reduced, thereby suppressing the impact of false triggering on the overall judgment.

[0064] Controller 5 will integrate the signals With preset inhalation threshold Comparison: When When, it is determined to be the inspiratory phase; when When the time is right, it is determined to be the expiratory phase, and a respiratory phase signal is output.

[0065] In one embodiment of the present invention, the controller 5 controls the inspiratory start time of the first N respiratory cycles. Store the data and calculate the predicted time of the next inhalation start using the moving average. :

[0066]

[0067] Where N is the length of the sliding window, the controller 5 adaptively adjusts the value of N according to the degree of fluctuation of the patient's respiratory rate: when the respiratory rate is relatively stable, N takes a larger value (e.g., 8-12), and when the respiratory rate fluctuates greatly, N takes a smaller value (e.g., 3-5), so as to balance prediction stability and following speed.

[0068] Controller 5 presets a time in advance before predicting T_. Send a pre-trigger command to the atomization module. The value ranges from 50ms to 100ms. The advance amount is adaptively adjusted according to the patient's current respiratory rhythm to minimize the deviation between the time of the pre-trigger command issuance and the actual start time of the next inspiratory phase.

[0069] In one embodiment of the present invention, the impedance measurement circuit synchronously acquires the resonant frequency offset of the microgrid transducer 3 relative to a clean state reference value during low-power pulse excitation. ,in The reference value for the resonant frequency in the clean state. The current measured value and the change in impedance modulus. ,in The reference value for impedance modulus in the clean state. The measured impedance magnitude and phase drift are... ,in The phase angle reference value is for the clean state. This represents the currently measured impedance phase angle.

[0070] Controller 5 calculates the microgrid efficiency value η using a three-parameter weighted fusion model.

[0071]

[0072] in The fusion weight coefficients of the three parameters satisfy... , The range of values ​​is , This indicates that the microgrid is in a clean and ideal state. A smaller value indicates more severe deposition on the micromesh walls and lower atomization efficiency. (Baseline value) Automatically updated and stored in controller 5 after each thorough cleaning or device initialization.

[0073] In another embodiment of the present invention, the controller 5 divides the working time of the microgrid transducer 3 into two stages according to the breathing phase.

[0074] The first stage is the pre-nebulization stage, which starts after responding to the pre-trigger command at the end of the expiratory phase. Controller 5 drives the microgrid transducer 3 in a low-power pulse mode to pre-charge the dead space at the inner node of the three-way tube 2 with nebulized medication. The pre-charge amount is... This allows the patient to receive an initial concentration of the drug with their first breath. Simultaneously, the impedance measurement circuit synchronously acquires the resonant frequency shift of the microgrid transducer 3 during this pulse excitation. Change in impedance modulus and phase drift The controller 5 inputs the three parameters into the fusion model to obtain the current microgrid efficiency value. .

[0075] The second stage (flow ratio modulation stage) covers the entire inhalation process. Let the target dose of the prescription be... The pre-charge phase has delivered a dose of The target dose that needs to be supplemented during the inspiratory phase is At a real-time inspiratory flow rate of At that moment, the corrected drive power of the microgrid transducer 3 Modulation is performed according to the following formula:

[0076]

[0077] in The proportionality coefficient is determined by controller 5 based on the prescription dosage target. Dynamic calculations ensure that the total amount of atomized drug delivered during the entire inhalation phase is equal to... ;when During descent, This improvement over the same period last year compensates for the nebulization efficiency reduction caused by deposits on the pore walls of the micro-mesh nebulizer 10, ensuring that the actual delivered dose always matches the prescribed target dose. The above two-stage scheduling forms a self-calibrating closed loop per respiratory cycle. The first stage measures... Substitute the power equation, execute the second stage of atomization output, and enter the next cycle to remeasure. .

[0078] In one embodiment of this invention, after the controller 5 detects the expiratory phase signal, the drive phase of the micro-mesh transducer 3 is reversed during the expiratory phase. A reverse drive pulse sequence is applied to the micro-mesh transducer 3, causing the micro-mesh nebulizer 10 to vibrate in the opposite direction to the transducer's vibration direction when generating nebulized medication. This removes deposits from the pore walls of the micro-mesh nebulizer 10 towards the medication cup, restoring the effective pore size of the micro-mesh nebulizer 10. The reverse drive pulse is executed only during the expiratory phase, when the patient is not inhaling medication, thus eliminating the risk of accidental inhalation of nebulized medication.

[0079] After the reverse drive pulse is executed, the impedance measurement circuit again acquires the resonant frequency offset. Change in impedance modulus and phase drift Calculate the efficiency value of the microgrid after cleaning. Controller 5 will display the efficiency value before cleaning. Efficiency value after cleaning The difference This amount is used to restore the efficiency of this cleaning and is stored in the historical cleaning record.

[0080] Controller 5 before each cleaning Drop to cleaning trigger threshold The time interval experienced Statistical analysis revealed the pattern of efficiency decay time. (Summary) and The timing of the next cleaning cycle is dynamically predicted to obtain an adaptive cleaning cycle. This enables self-learning cleaning cycle management.

[0081] One embodiment provided by the present invention, such as Figure 9 As shown, the drive and impedance measurement multiplexing circuit adopts a half-bridge topology, with the upper transistor Q1 being a P-type MOSFET and the lower transistor Q2 being an N-type MOSFET. Controller 5 outputs a complementary PWM signal: When the voltage is low (0V), the gate-source voltage of Q1 is:

[0082] The P-MOS turn-on threshold condition is met. Q1 is turned on; When it is high, the gate-source voltage of Q2 Exceeding the N-MOS turn-on threshold ( Q2 is turned on. The controller has a built-in complementary PWM output. Dead time, guarantee and Not both are effective simultaneously to prevent short circuits caused by direct connection between the upper and lower pipes. This is the gate drive signal for the upper transistor. This is the gate drive signal for the lower transistor.

[0083] Regarding current sampling, the typical drive power of microgrid transducer 3 is... Equivalent load approximately Typical peak current range is With the maximum peak current Calculate the current sampling resistor. Instrumentation amplifier gain At that time, the voltage at the sampling point lower than Full scale, within the effective sampling range. Regarding voltage sampling, the drive power supply... The maximum sampled voltage after passing through a 10:1 voltage divider network is Similarly in Within the measurement range.

[0084] During impedance measurement, controller 5 uses the transducer terminal voltage sample value acquired by the ADC. and current sampling value The actual parameters are restored according to the following relationship: the actual terminal voltage of microgrid transducer 3. Actual driving current = The impedance modulus of microgrid transducer 3 .

[0085] During self-cleaning, the controller 5 shifts the complementary PWM phase by 180°, causing the micro-mesh transducer 3 to be driven in the opposite half-cycle to normal atomization, generating reverse vibration and peeling the deposits on the pore wall of the micro-mesh atomizing plate 10 towards the medicine cup 4.

[0086] One embodiment provided by the present invention, such as Figure 10 As shown, in the thermocouple differential sensor array signal conditioning circuit, the sensitivity of the K-type thermocouple sensor 9 is... When the temperature difference between the airflow and the pipe wall is At that time, the amplitude of the thermocouple output signal is ; after gain The output voltage after amplification by the instrumentation amplifier is More than 12 characters exist Approximately at reference voltage Its minimum resolution allows for accurate differentiation of temperature changes caused by airflow.

[0087] Each thermocouple sensor has 9 signal input terminals connected in series. The filter resistor and the distributed capacitance of the thermocouple connection cable (approximately) Together, they form a low-pass filter network with a cutoff frequency of [missing information]. Approximately This also limits the short-circuit current and suppresses electromagnetic interference. The patient's respiratory rate range is... The frequency is far below the cutoff frequency, so the filter will not introduce phase error into the respiratory rhythm signal and will not affect the determination of the differential timing gradient. The LM35 temperature sensor uses... The proportional output ambient temperature signal is connected to the reference terminal of the instrumentation amplifier to compensate for changes in the cold junction temperature of the thermocouple in real time, thereby improving the measurement accuracy of absolute temperature.

[0088] For timing detection, the ADC sampling rate is set to... The time resolution is The actual airflow propagation time difference between the sensing units of the differential sensing array. about ,satisfy The timing resolution requirement is met. Controller 5 uses the same timer to trigger the event simultaneously to start the dual-channel ADC conversion, eliminating spurious timing gradients introduced by inconsistent sampling times and ensuring the accuracy of differential timing measurement results.

[0089] Simultaneous triggering of the same timer event in CU and The transformation eliminates spurious temporal gradients caused by sampling time differences.

[0090] In one embodiment of the present invention, the output signal of the impedance measurement circuit includes a low-frequency modulation component generated by airflow modulation. When the patient breathes, the airflow periodically modulates the mechanical vibration of the microgrid transducer 3. The frequency of this low-frequency modulation component is similar to the patient's breathing frequency, and its amplitude and phase changes are related to the direction of inhalation or exhalation of the respiratory airflow.

[0091] The controller 5 uses this low-frequency modulation component as the third breathing phase judgment signal, and combines it with the weighted fusion signal from the thermocouple sensor 9 in the differential sensing array. (First path) and airflow time gradient (Second path) Perform a three-way majority vote verification. If at least two of the three signals have the same judgment, then adopt the consistent judgment as the result of the current respiratory phase judgment, eliminate the influence of misjudgment of a single signal on the overall judgment, and obtain the verified respiratory phase signal.

[0092] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles 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 respiration-triggered microgrid nebulizer based on a thermocouple sensor, characterized in that, Includes a three-way tube, a breathing sensor module, a nebulizer module, and a controller; The three-way tube has a first port, a second port and a third port. The first port is used to connect to the patient's airway, the third port is used to connect to the ventilator circuit, and the second port is connected to the nebulizer module. The atomization module includes a micro-mesh transducer disposed at the end of the second port, a micro-mesh atomizing plate disposed within the micro-mesh transducer, and a liquid medicine cup disposed above the micro-mesh transducer. The breathing sensing module includes a flexible circuit board and a differential sensing array disposed on the flexible circuit board. The differential sensing array includes a plurality of sensing units spaced apart along the airflow channel direction of the three-way tube. Each sensing unit includes at least a thermocouple sensor. The atomization module includes a microgrid transducer and a driving circuit integrated on the flexible circuit board. The driving circuit is provided with an impedance measurement circuit, which is electrically connected to the microgrid transducer. The controller is electrically connected to the respiratory sensing module and the nebulization module respectively, and is used to perform weighted fusion processing on the signals output by the sensing units in the differential sensing array to obtain the patient's respiratory phase signal; The respiratory phase signal of the current respiratory cycle is compared and analyzed with the respiratory phase signal of the historical respiratory cycles to obtain a respiratory frequency information set. The start time of the next inhalation is predicted based on the respiratory frequency information set, and a pre-trigger command is sent to the nebulization module at the end of the current expiratory phase. In response to the pre-trigger command, the microgrid transducer is driven in a low-power pulse mode to pre-charge the inner cavity of the three-way tube with atomized medicine; The microgrid efficiency value is obtained by fusing the resonant frequency shift, impedance magnitude change, and phase angle drift of the microgrid transducer collected by the impedance measurement circuit. During the inspiratory phase, the real-time inspiratory flow rate is detected, the transducer drive power is proportionally adjusted to the real-time inspiratory flow rate, and the microgrid efficiency value is incorporated into the compensation correction of the drive power to obtain the corrected drive power, so that the nebulized drug dose delivered with each breath matches the prescription target amount.

2. The respiration-triggered microgrid nebulizer based on a thermocouple sensor according to claim 1, characterized in that, The controller is electrically connected to both the respiratory sensing module and the nebulization module, and is used to perform weighted fusion processing on the signals output by the sensing units in the differential sensing array to obtain the patient's respiratory phase signal. It also includes: During the exhalation phase, the drive phase of the transducer is reversed, and a reverse drive pulse sequence is applied to the micro-mesh transducer, causing the micro-mesh to vibrate in the opposite direction to the transducer vibration when the nebulized drug is generated. This peels off the deposits on the micro-mesh pore wall towards the drug cup side and restores the effective pore size of the micro-mesh. After the reverse drive pulse is executed, the resonant frequency shift, impedance magnitude change and phase angle drift of the microgrid transducer are collected again through the impedance measurement circuit to obtain the microgrid efficiency value after cleaning. The microgrid efficiency values ​​before and after cleaning are compared and recorded to predict the timing of subsequent cleaning.

3. The respiration-triggered microgrid nebulizer based on a thermocouple sensor according to claim 1, characterized in that, The controller is electrically connected to both the respiratory sensing module and the nebulization module, and is used to perform weighted fusion processing on the signals output by the sensing units in the differential sensing array to obtain the patient's respiratory phase signal. It also includes: The low-frequency modulation component generated by airflow modulation in the output signal of the impedance measurement circuit is extracted, and the low-frequency modulation component is compared and verified with the signal of the thermocouple sensor in the differential sensing array. The respiratory phase signal is cross-verified to obtain the verified respiratory phase signal.

4. The respiration-triggered microgrid nebulizer based on a thermocouple sensor according to claim 1, characterized in that, The sensing units in the differential sensing array also include a humidity sensor and a carbon dioxide sensor; The arrival times of signals from the sensing units in the differential sensing array along the airflow channel direction are detected, including the arrival times of the humidity sensor, the carbon dioxide sensor, and the thermocouple sensor. The arrival time differences between the signals from the humidity sensor and the carbon dioxide sensor, and between the signals from the humidity sensor and the thermocouple sensor, are extracted to obtain the airflow time-series gradient. This airflow time-series gradient is then used together with the weighted fusion processing result to predict the inhalation start time.

5. The respiration-triggered microgrid nebulizer based on a thermocouple sensor according to claim 1, characterized in that, The impedance measurement circuit and the driving circuit reuse the traces on the flexible circuit board; during the low-power pulse drive of the microgrid transducer to complete the pre-charging of the atomized drug solution, the impedance measurement circuit simultaneously collects the resonant frequency shift, impedance magnitude change and phase angle drift of the transducer under the low-power pulse excitation to obtain the microgrid efficiency value.

6. The respiration-triggered microgrid nebulizer based on a thermocouple sensor according to claim 4, characterized in that, Using the airflow temporal gradient and the weighted fusion processing result together to predict the inhalation initiation time also includes: When performing weighted fusion processing on the signals output by the sensor units in the differential sensor array, the historical misclassification rates of the sensor units in the differential sensor array are statistically analyzed. The weights corresponding to sensor units with lower misclassification rates are set to larger values, and the weights corresponding to sensor units with higher misclassification rates are set to smaller values. The weights of the sensor units in the differential sensor array are dynamically adjusted. The adjusted weights are then weighted and summed with the corresponding sensor unit signals to obtain the comprehensive respiratory phase signal. The comprehensive signal is then compared with a preset inspiratory threshold to obtain the respiratory phase signal.

7. The respiration-triggered microgrid nebulizer based on a thermocouple sensor according to claim 1, characterized in that, The step of comparing and analyzing the respiratory phase signal of the current respiratory cycle with the respiratory phase signal of historical respiratory cycles to obtain a respiratory frequency information set, predicting the start time of the next inhalation based on the respiratory frequency information set, and issuing a pre-trigger command to the nebulization module at the end of the current expiratory phase also includes: The controller stores the inspiratory start times of the previous N respiratory cycles and calculates the moving average of these N inspiratory start times to obtain the predicted inspiratory start time of the next respiratory cycle. The controller adaptively adjusts the value of N according to the fluctuation of the patient's respiratory rate, taking a larger value when the respiratory rate is stable and a smaller value when the respiratory rate fluctuates greatly. A pre-trigger command is sent to the nebulization module before the predicted inspiratory start time of the next respiratory cycle. The advance amount is adaptively adjusted according to the patient's current respiratory rhythm. The advance amount is the time advance of the sending time of the pre-trigger command relative to the predicted inspiratory start time of the next respiratory cycle, and the advance amount is adaptively adjusted within a preset range according to the patient's current respiratory rhythm.

8. The respiration-triggered microgrid nebulizer based on a thermocouple sensor according to claim 1, characterized in that, The step of responding to the pre-trigger command by driving the microgrid transducer in a low-power pulse mode and pre-filling the inner cavity of the three-way tube with atomized drug solution further includes: During the inspiratory phase, the controller uses the difference between the prescribed target dose and the dose already delivered during the pre-filling phase of the nebulized drug solution as the target dose to be supplemented during the inspiratory phase. The transducer drive power is set to be directly proportional to the real-time inspiratory flow rate, and the drive power is set to be inversely proportional to the microgrid efficiency value. When the microgrid efficiency value decreases, the drive power is increased proportionally to ensure that the total amount of nebulized drug solution delivered during the inspiratory phase matches the target dose.

9. The respiration-triggered microgrid nebulizer based on a thermocouple sensor according to claim 2, characterized in that, The process of fusing the microgrid transducer resonant frequency shift, impedance magnitude change, and phase angle drift acquired by the impedance measurement circuit to obtain the microgrid efficiency value also includes: The controller calculates the difference in microgrid efficiency values ​​before and after cleaning to obtain the efficiency recovery amount for a single cleaning cycle; it also statistically analyzes the time intervals during which the efficiency value drops to the cleaning trigger threshold before each cleaning cycle to obtain the efficiency decay time pattern; and it comprehensively analyzes the cleaning efficiency recovery amount and the efficiency decay time pattern to predict the timing of subsequent cleaning triggers and obtain the adaptive cleaning cycle.

10. The respiration-triggered microgrid nebulizer based on a thermocouple sensor according to any one of claims 1 to 9, characterized in that, The controller includes: The sensing fusion unit is used to acquire signals from the sensing units in the differential sensing array, perform weighted fusion processing on the acquired multi-channel signals, and obtain the patient's respiratory phase signal. The phase prediction unit is used to periodically store the respiratory phase signal output by the perception fusion unit, compare and analyze the respiratory phase signal of the current respiratory cycle with the respiratory phase signal of the historical respiratory cycle, predict the start time of the next inhalation, and generate a pre-trigger command at the end of the expiratory phase. The drive scheduling unit is used to receive the pre-trigger command from the phase prediction unit, drive the transducer in a low-power pulse mode at the end of expiration to complete the pre-filling of the nebulized drug solution; during the inspiratory phase, the real-time inspiratory flow rate is detected, and the drive power is proportionally adjusted to the inspiratory flow rate to obtain the adjusted drive power. The efficiency compensation unit is used to fuse the resonant frequency offset, impedance magnitude change and phase angle drift collected by the impedance measurement circuit to obtain the microgrid efficiency value, and input the microgrid efficiency value into the drive scheduling unit to compensate and correct the drive power to obtain the corrected drive power. The cleaning management unit is used to apply a reverse drive pulse to the transducer during the expiratory phase to peel off the deposits on the micromesh wall towards the drug cup side, compare and record the micromesh efficiency values ​​before and after cleaning, and predict the timing of subsequent cleaning triggers.

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