Portable lung function instrument based on thermal flow measurement and lung function measurement method

Abstract

The invention provides a portable pulmonary function instrument based on thermal flow measurement and a pulmonary function measurement method, and relates to the technical field of pulmonary function instrument research, the pulmonary function instrument comprises a sensor assembly, a hardware circuit, a microcontroller and a client; the thermal airflow sensor adopting the bypass airflow channel design is applied to the lung function instrument, so that higher sensing precision, lower power consumption and smaller size are realized, the measuring range of the lung function instrument is improved, and the effects of small size, portability, simplicity and convenience in operation and high measuring precision of the lung function instrument are achieved.

Description

Technical Field

[0001] The present application relates to the technical field of pulmonary function instrument research, and in particular to a portable pulmonary function instrument based on thermal flow measurement and a pulmonary function monitoring method. Background Art

[0002] Against the backdrop of an aging population, people with respiratory diseases are at high potential risk, leading to a growing demand for respiratory disease monitoring and testing equipment in the medical market. For patients with respiratory diseases such as chronic obstructive pulmonary disease, the need for early screening and diagnosis has become particularly urgent.

[0003] Chronic respiratory diseases have become the fourth leading cause of death in the world, and the mainstream and effective screening method for spontaneous breathers is pulmonary function tests. Pulmonary function tests can evaluate the basic respiratory function of the subjects and help doctors to clinically identify the type and severity of pulmonary dysfunction. Pulmonary function tests are one of the important examination methods for respiratory diseases, mainly used to check pulmonary ventilation function and diffusion function. They have important clinical value in the early diagnosis of respiratory diseases, disease severity assessment, prognosis judgment, drug efficacy judgment, and surgical tolerance assessment. Large-scale laboratory pulmonary function testing instruments are large and bulky, expensive, and complicated to operate. This traditional pulmonary function test generally needs to be performed in secondary and above hospitals, resulting in a serious lack of pulmonary function examination rates in primary hospitals and communities, resulting in a large number of chronic respiratory diseases being missed.

[0004] Portable spirometers meet the strategic needs of the country and have the advantages of easy operation, strong portability, low price, and convenient quality control. They can be used as ideal screening equipment for early disease screening, large-scale epidemiological surveys, and health examinations. They can be widely used in primary hospitals, community clinics, and physical examination centers, effectively promoting the early screening of chronic respiratory diseases and the improvement of intervention capabilities. In addition, occupational lung disease diagnosis or lung function testing in remote areas may need to be conducted in factories, mines, or in the wild. Portable spirometers can provide a flexible solution.

[0005] Given that my country started slowly and developed late in key sensor chips and technologies related to pulmonary function meters, as well as the lack of attention paid to chronic respiratory diseases, the domestically developed portable pulmonary function screening equipment currently on the domestic market is far behind that of foreign countries. The measurement accuracy and stability cannot be guaranteed, and the portability and interactive design are not as good as foreign advanced products. In addition, only large tertiary hospitals and some grassroots hospitals in my country currently have high-performance pulmonary function screening equipment, professional physicians and screening processes, and can provide patients with professional step-by-step guidance for testing; but there is a lack of more popular, easily accessible, high-precision, intelligent, and high-performance portable pulmonary function meters.

[0006] Therefore, focusing on the research and development of medical portable high-performance intelligent pulmonary function instruments will help lay the foundation for the development of domestic high-end portable pulmonary function instrument products and break the technical barriers and market monopoly of foreign equipment in China. Summary of the invention

[0007] The purpose of this application is to provide a portable pulmonary function instrument and pulmonary function monitoring method based on thermal flow measurement, which can achieve the effects of being compact and portable, easy to operate and having high measurement accuracy.

[0008] To achieve the above objectives, this application provides the following solutions:

[0009] In a first aspect, the present application provides a portable pulmonary function meter based on thermal flow measurement, comprising:

[0010] Sensor components, hardware circuits, microcontrollers, and clients;

[0011] The sensor component is connected to the microcontroller via the hardware circuit;

[0012] The microcontroller is in communication connection with the client;

[0013] The sensor assembly is used to collect airflow data, wherein the sensor assembly is a thermal airflow sensor, the thermal airflow sensor comprises an airflow sensor chip and a flow channel, the flow channel comprises a main airflow flow channel and a bypass airflow flow channel, the airflow sensor chip is packaged in the bypass airflow flow channel, the cross-sectional area of ​​the main airflow flow channel and the cross-sectional area of ​​the bypass airflow flow channel satisfy a preset area ratio, and the cross-sectional area of ​​the bypass airflow flow channel is smaller than the cross-sectional area of ​​the main airflow flow channel;

[0014] The microcontroller is used to obtain an airflow-time curve according to the airflow data;

[0015] The client is used to extract characteristic data of the user's lung function test according to the airflow-time curve.

[0016] In a second aspect, the present application provides a method for monitoring lung function, wherein the lung function measurement method is implemented using the portable lung function meter based on thermal flow measurement described in the first aspect, and the lung function measurement method comprises:

[0017] Obtaining air flow-time curve;

[0018] Numerically integrating the airflow-time curve along the time axis to obtain a pulmonary ventilation volume-time curve;

[0019] Dividing the airflow-time curve into a plurality of breathing cycles, wherein each breathing cycle includes a complete process of exhalation and inhalation;

[0020] Obtaining a flow-volume graph according to the airflow-time curve and the pulmonary ventilation volume-time curve corresponding to each respiratory cycle;

[0021] The characteristic data of the user's lung function test are extracted according to the airflow-time curve and the flow-volume diagram corresponding to each breathing cycle.

[0022] According to the specific embodiments provided in this application, this application has the following technical effects:

[0023] The present application provides a portable pulmonary function meter based on thermal flow measurement and a pulmonary function monitoring method, wherein the pulmonary function meter comprises: a sensor component, a hardware circuit, a microcontroller and a client; by applying a thermal air flow sensor with a bypass airflow channel design in the pulmonary function meter, higher sensing accuracy, lower power consumption and smaller volume are achieved, and the measurement range of the pulmonary function meter is improved, so that the pulmonary function meter is small and portable, easy to operate and has high measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 This is a schematic structural diagram of a portable pulmonary function meter based on thermal flow measurement in Example 1 of the present application;

[0026] FIG2( a ) is a schematic diagram of a three-dimensional model of a bypass flow channel in Example 1 of the present application;

[0027] FIG2( b ) is a top view of the Bypass flow channel in Example 1 of the present application;

[0028] FIG2( c ) is a front view of the Bypass flow channel in Example 1 of the present application;

[0029] FIG2( d ) is a left view of the Bypass flow channel in Example 1 of the present application;

[0030] Figure 3 Schematic diagram of the gas path design for the Bypass flow channel test in Example 1 of the present application;

[0031] FIG4( a ) is a design diagram of a package cover plate of an air flow sensor chip in Example 1 of the present application;

[0032] FIG4( b ) is a schematic diagram of the packaging of the air flow sensor chip in Example 1 of the present application;

[0033] FIG4( c ) is a physical picture of the air flow sensor chip in Example 1 of the present application;

[0034] Figure 5 This is a calibration curve diagram of air flow rate-voltage output obtained when testing and calibrating the thermal air flow rate sensor designed for the Bypass flow channel in Example 1 of the present application;

[0035] Figure 6 This is a schematic diagram of the structure of the hardware circuit in Example 1 of the present application;

[0036] Figure 7 This is a flowchart of the single-chip computer program in Example 1 of the present application;

[0037] Figure 8 This is a schematic diagram of the circuit structure of the single chip microcomputer in Example 1 of the present application;

[0038] Fig. 9 This is a flowchart of the lung function meter analysis algorithm program in Example 1 of the present application;

[0039] Fig.10 A flowchart of the user interaction software design for the pulmonary function meter in Example 1 of the present application;

[0040] FIG. 11( a ) is a data display and connection main page of the pulmonary function test in Example 1 of the present application;

[0041] FIG. 11( b ) is a core operation and display page of the pulmonary function test in Example 1 of the present application;

[0042] FIG. 11( c ) is a real-time display and result analysis page of the pulmonary function test in Example 1 of the present application;

[0043] FIG12( a) is a physical picture of the pulmonary function instrument in Example 1 of the present application;

[0044] FIG12( b ) is a schematic diagram of a user using a pulmonary function meter in Example 1 of the present application;

[0045] FIG12( c ) is a schematic diagram of real-time sensing data of the thermal air flow sensor in Example 1 of the present application;

[0046] FIG12( d ) is a graph showing the real-time airflow rate during the lung function test in Example 1 of the present application;

[0047] Figure 12(e) is a schematic diagram of the analysis results after the lung function test in Example 1 of the present application. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0049] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0050] Example 1

[0051] This embodiment provides a portable pulmonary function meter based on thermal flow measurement, including: a sensor component, a hardware circuit, a microcontroller and a client.

[0052] The sensor component is connected to the microcontroller through the hardware circuit.

[0053] The microcontroller is in communication connection with the client.

[0054] The sensor assembly is used to collect air flow data, wherein the sensor assembly is a thermal air flow sensor, the thermal air flow sensor includes an air flow sensor chip and a flow channel, the flow channel includes a main air flow channel and a bypass air flow channel, the air flow sensor chip is encapsulated in the bypass air flow channel, the cross-sectional area of ​​the main air flow channel and the cross-sectional area of ​​the bypass air flow channel satisfy a preset area ratio, and the cross-sectional area of ​​the bypass air flow channel is smaller than the cross-sectional area of ​​the main air flow channel.

[0055] The microcontroller is used to obtain an airflow-time curve according to the airflow data.

[0056] The client is used to extract characteristic data of the user's lung function test according to the airflow-time curve.

[0057] The client comprises a pulmonary ventilation volume-time curve generating module, a data preprocessing module, a flow volume graph generating module and a feature calculating module.

[0058] The pulmonary ventilation volume-time curve generation module is used to perform numerical integration of the airflow volume-time curve along the time axis to obtain the pulmonary ventilation volume-time curve.

[0059] The data preprocessing module is used to divide the airflow-time curve into a plurality of breathing cycles, wherein each breathing cycle includes a complete exhalation and inhalation process.

[0060] The flow volume diagram generation module is used to obtain a flow volume diagram according to the air flow-time curve and the lung ventilation volume-time curve corresponding to each respiratory cycle.

[0061] The feature calculation module is used to extract feature data of the user's lung function test based on the airflow-time curve and flow-volume diagram corresponding to each breathing cycle.

[0062] The hardware circuit includes a sensor readout bridge, a voltage amplification circuit and an ADC sampling module which are connected in sequence; and also includes a temperature compensation module.

[0063] The sensor readout bridge is connected to the sensor assembly.

[0064] The ADC sampling module is connected to the microcontroller.

[0065] The sensor readout bridge circuit is used to convert the air flow data into a voltage signal.

[0066] The voltage amplifier circuit is used to perform differential amplification and noise reduction processing on the voltage signal to obtain an amplified and noise-reduced voltage signal.

[0067] The ADC sampling module is used to perform analog-to-digital conversion on the amplified and noise-reduced voltage signal to obtain a digital signal.

[0068] The temperature compensation module is connected to the sensor component and the sensor readout bridge circuit respectively.

[0069] The temperature compensation module is used to monitor the temperature change of the sensor component in real time and adjust the voltage signal according to the temperature change.

[0070] This embodiment applies a thermal airflow sensor to a pulmonary function meter. Compared with a differential pressure airflow / airflow volume sensor, a pressure airflow / airflow volume sensor, a turbine airflow / airflow volume sensor, and an ultrasonic airflow / airflow volume sensor, it can achieve higher sensing accuracy, lower power consumption, and smaller size, and is more suitable for use in a portable pulmonary function meter.

[0071] Although the thermal air flow sensor has the advantages of high accuracy, two-way detection, high sensitivity, faster response time and smaller volume, it also has the problem of relatively small range. Therefore, in order to apply the sensor to a pulmonary function meter with a large range requirement (one-way air flow range of 0-1000SLM), this embodiment adopts a Bypass design in the flow channel design of the sensor to increase its measurement range at a low cost from a physical level.

[0072] This embodiment takes into account the impact of temperature changes of the thermal flow sensor on the sensor's measurement accuracy: when a person breathes, the temperature of the exhaled and inhaled gases changes, and is greatly affected by the external temperature. Thermal sensors based on heat sensing are sensitive to temperature changes and are easily affected by temperature, thereby affecting the measurement accuracy. In response to this, this embodiment designs a temperature compensation module to reduce or even eliminate the impact of temperature changes on the sensor's measurement accuracy.

[0073] In order to make the structure, function and use method of the portable pulmonary function instrument based on thermal flow measurement in this embodiment more clear to those skilled in the art, the following Figure 1-Figure 1 2 provide specific explanation.

[0074] (1) Overall design of a portable pulmonary function meter based on thermal flow measurement.

[0075] The overall block diagram of the portable pulmonary function instrument based on thermal flow measurement is as follows Figure 1 As shown, the portable pulmonary function meter based on thermal flow measurement includes software and hardware design. The hardware design includes a thermal airflow sensor (specifically a Bypass MEMS thermal airflow sensor, including a sensor chip and a Bypass flow channel, and the sensor chip is encapsulated in the Bypass flow channel), a hardware circuit and an MCU (microcontroller, i.e., an ESP32 single-chip microcomputer). The hardware design provides a sensing function for measuring respiratory airflow and a communication function for transmitting data with a smartphone; the software design includes single-chip microcomputer program design and user interactive software and algorithms based on a smartphone APP (i.e., a client), which are used to provide data processing, display, interaction and management functions.

[0076] (1.1) Design of thermal gas flow sensor.

[0077] In this embodiment, the airflow channel of the Bypass-type MEMS (Microelectromechanical Systems) thermal airflow sensor adopts a By-pass design. The flow channel of the sensor is divided into a main airflow channel and a bypass airflow channel. There is a certain cross-sectional area ratio between the main airflow channel and the bypass airflow channel. The cross-sectional area of ​​the bypass airflow channel is much smaller than the cross-sectional area of ​​the main airflow channel, and the airflow sensor chip is encapsulated in the main airflow channel. The reason for adopting such a design is that when the range of the thermal airflow chip is limited, it is beneficial to increase the range of the sensor, that is, the range required by the pulmonary function meter. The three-dimensional model three-view drawing and three-dimensional cross-sectional drawing of the By-pass flow channel design are shown in the figure. Figure 2(a)-Figure 2(d) shown.

[0078] The bypass flow path is tested and calibrated using a large-scale Alicat Scientific MCR-1000SLPMBUS / GAS:Air.(3v6) gas flow sensor. This mass flow controller measures and controls gas flow from 10SCCM to 1000SLPM with an accuracy of ±0.8% of reading or ±0.2% of full scale, and a control range of 0.01-100% (10000:1). The design of the calibration test gas path is as follows: Figure 3 shown.

[0079] FIG4(a) is a design drawing of the airflow sensor chip packaging cover, FIG4(b) is a schematic diagram of the airflow sensor chip packaging, and FIG4(c) is a physical picture of the airflow sensor chip. The packaging process includes: designing and processing a grooved cover insulated with POM material, sealing a specially designed immersion gold PCB therein, sealing the airflow sensor chip into the packaging groove reserved in the PCB, and using a gold wire bonding machine to bond the Pad on the airflow sensor chip and the Pad on the PCB to make electrical connections.

[0080] Afterwards, assemble the air flow sensor chip packaging board into the reserved position of the Bypass flow channel, and electrically connect the reserved sensor chip interface with the external circuit PCB.

[0081] like Figure 4(a)-Figure 4(c) As shown, the packaging features of the above-mentioned packaging cover, air flow sensor chip, PCB and bypass flow channel are described as follows:

[0082] 1. Composition relationship: The air flow sensor chip includes a packaging cover, a PCB, an air flow sensor chip and a By-pass flow channel.

[0083] 2. Position relationship: The front side of the PCB is embedded in the groove of the package cover plate with the front side facing upward, and the air flow sensor chip is embedded in the chip slot of the chip package PCB. The side of the package cover plate with the chip faces downward and covers the top of the By-pass flow channel, above the By-pass flow channel.

[0084] 3. Connection relationship: The chip package PCB (i.e. PCB) is embedded in the groove of the chip package cover (i.e. package cover) with the front side facing up, and the electrical through-holes of the package cover are aligned with the chip package PCB when embedded. The airflow sensor chip is embedded in the chip slot of the chip package PCB and fixed by adhesion. The connection relationship between the chip package cover embedded with the chip package PCB and the By-pass flow channel is: the package cover with the chip side facing down is covered on the top of the By-pass flow channel, the package cover screw aperture is aligned with the By-pass flow channel screw aperture, and the screws are locked in to achieve physical connection.

[0085] Finally, connect it to the calibration test gas circuit, control different ventilation gas flows, record the electrical output of the sensor, perform testing and calibration, and obtain the following results: Figure 5 The gas flow-voltage output calibration curve is shown in FIG. The piecewise linear data fitting is performed through the calibration curve.

[0086] (1.2) Hardware circuit design.

[0087] The schematic diagram of the hardware circuit design is as follows Figure 6 As shown in the figure, the hardware circuit includes a sensor readout bridge, a voltage amplifier circuit, a temperature compensation module, and a high-precision ADC sampling module based on the ADS1118 chip. Among them, the sensor readout bridge adopts a Wheatstone bridge, which forms a Wheatstone bridge with the two temperature detection resistors of the thermal air flow sensor. The bridge is used to adjust the voltage of the differential pressure output. The two output voltages are connected to the instrument amplifier chip for differential amplification and noise reduction, and finally the single-ended amplified output is connected to the ADC as the output of the sensor for analog-to-digital conversion.

[0088] The temperature compensation module is used to monitor the temperature change of the sensor component in real time and adjust the voltage signal according to the temperature change to ensure accurate measurement under different temperature conditions.

[0089] The actual circuit design of the thermal air flow sensor: Use PCB circuit board to make the circuit line, and solder the electronic components to the PCB circuit board, connect the analog output interface on the circuit to the ADS1118 analog-to-digital converter (ADC) through electrical connection, as shown below Figure 1 The wiring method shown electrically connects the ADS1118 chip to the ESP32 microcontroller to enable the ESP32 microcontroller to drive the ADS1118 and read data.

[0090] (1.3) MCU microcontroller and circuit wiring method and program design.

[0091] The wiring scheme of the ESP32 microcontroller (MCU) and the circuit is as follows Figure 6 As shown in the figure (SPI communication, Serial Peripheral Interface). The ESP32 microcontroller is the microcontroller of this pulmonary function meter, responsible for ADC drive control, digital signal reading and Bluetooth communication data transmission. The microcontroller program design flow chart is as follows Figure 7 The circuit structure of the microcontroller is shown in Figure 8 shown.

[0092] (1.4) Spirometry analysis algorithm and user interactive software design.

[0093] The design of spirometry analysis algorithm is as follows Fig. 9 As shown in Figure 1, the algorithm is mainly used to analyze and extract the characteristic data of the user's lung function test, including FVC (ventilation volume / vital capacity during forced exhalation), PFE (peak airflow during forced exhalation), FEV1 (expiratory volume in the first second of forced exhalation), FEV1 / FVC, VCMAX (maximum vital capacity), MEF25 (the airflow value corresponding to the remaining 25% of the maximum expiratory volume of exhaled gas), MEF50 (the airflow value corresponding to the remaining 50% of the maximum expiratory volume of exhaled gas) and MEF75 (the airflow value corresponding to the remaining 75% of the maximum expiratory volume of exhaled gas), among which the FEV1 / FVC index is often used as the gold standard for clinical diagnosis of COPD. In addition, there is also the generation of flow-volume graphs to describe the changing trends of ventilation volume and corresponding airflow during lung function tests. The specific process of analyzing and extracting the characteristic data of user lung function tests is as follows.

[0094] S1. Read the airflow-time series stored during the pulmonary function test, perform numerical integration of the airflow-time curve along the time axis, and obtain a real-time changing pulmonary ventilation volume-time curve. The volume value and time value of the pulmonary ventilation volume-time curve are also stored in real time. The integration formula is shown in formula (1).

[0095]

[0096] In formula (1), Fr is the air flow data, t is the time, i is the index, and they are all one-to-one corresponding. n is the starting index, and m is the ending index.

[0097] S2. Read the stored airflow-time curve and perform data preprocessing. Because during the pulmonary function test, the tester needs to perform multiple quiet breathing and forced exhalation and inhalation, it is necessary to distinguish each breath. Therefore, data preprocessing has the following two steps:

[0098] S21. Correctly divide the airflow-time curve into different breathing cycles, i.e., a complete exhalation and inhalation process, and obtain the time interval corresponding to the complete exhalation part (the part with positive airflow value) in one breathing cycle, and intercept the airflow-time curve of this part according to the time interval.

[0099] S22. For each valid breathing cycle correctly divided, the corresponding time interval and the airflow-time curve and volume-time curve corresponding to the time interval are stored as pulmonary function test data for subsequent data analysis.

[0100] S3. A flow volume graph is generated for each cycle of data. The specific process of generating a flow volume graph is as follows.

[0101] S31. Obtain the air flow-time curve and volume-time curve corresponding to the time interval of the current cycle from the storage area, and further split and store the above two groups of curves according to the exhalation part and the inhalation part (the exhalation part is the part with positive air flow, and the inhalation part is the part with negative air flow).

[0102] S32. For the time interval of the exhalation part, the volume values ​​on the volume-time curve are traversed in chronological order. Every time a volume value is obtained at a time point, the corresponding airflow value at the time point is also obtained. The volume value and the airflow value are plotted as a point on a two-dimensional coordinate system with the ventilation volume as the x-axis and the airflow as the y-axis.

[0103] S33. For the time interval of the inhalation part, the volume values ​​on the volume-time curve are traversed in chronological order. Every time a volume value is obtained at a time point, the corresponding airflow value at the time point is also obtained. The volume value and the airflow value are plotted as a point on a two-dimensional coordinate system with the ventilation volume as the x-axis and the airflow as the y-axis.

[0104] S34. Connect the scatter plots on the coordinate system in order to draw a flow volume graph.

[0105] S4. After obtaining the correct lung function test data and flow volume graph to be analyzed, the index calculation and analysis are performed on the test data of each cycle, as follows:

[0106] 1. Calculate FVC: For each cycle, extract the expiratory air flow-time curve of the exhalation part (expiration is defined as the part with positive air flow), perform numerical integration along the time axis, and obtain the expiratory vital capacity FVC. The specific formula is shown in formula (1). The FVC value calculated for each respiratory cycle is stored, and the one with the highest FVC value is selected as the FVC indicator of the final test result.

[0107] 2. Calculate VCMAX: For each cycle, extract the expiratory air flow-time curve of the exhalation part (expiration is defined as the part with positive air flow), perform numerical integration along the time axis, and obtain the expiratory vital capacity VCMAX. The specific formula is shown in formula (1). The VCMAX value calculated for each respiratory cycle is stored, and the one with the highest FVC value is selected as the VCMAX indicator of the final test result. Usually, in a lung function test, the values ​​of FVC and VCMAX overlap.

[0108] 3. Calculate FEV1: For each cycle, extract the curve in the first second of the expiratory air flow-time curve (expiratory is defined as the part with positive air flow) of the expiratory part, perform numerical integration along the time axis, and obtain the expiratory vital capacity FEV1. The specific formula is shown in formula (2). The FEV1 value calculated for each respiratory cycle is stored, and the one with the highest FEV1 value is selected as the FEV1 index of the final test result.

[0109]

[0110] 4. Calculate FEV1 / FVC: Divide FEV1 by FVC and convert it into a percentage.

[0111] 5. Calculate MEF25: For each cycle, on the flow-volume graph, obtain the expiratory airflow value (positive part of the y-axis) corresponding to the capacity value (1-25%) of the maximum expiratory lung capacity (i.e. the maximum value on the x-axis) on the coordinate system. The MEF25 value calculated for each respiratory cycle is stored, and the highest value is selected as the MEF25 indicator of the final test result.

[0112] 6. Calculate MEF50: For each cycle, on the flow-volume graph, obtain the expiratory airflow value (positive part of the y-axis) corresponding to the capacity value (1-50%) of the maximum expiratory lung capacity (i.e. the maximum value on the x-axis) on the coordinate system. The MEF50 value calculated for each respiratory cycle is stored, and the highest value is selected as the MEF50 indicator of the final test result.

[0113] 7. Calculate MEF75: For each cycle, on the flow-volume graph, obtain the expiratory air flow value (positive part of the y-axis) corresponding to the capacity value (1-75%) of the maximum expiratory lung capacity (i.e. the maximum value on the x-axis) on the coordinate system. The MEF75 value calculated for each respiratory cycle is stored, and the highest value is selected as the MEF75 indicator of the final test result.

[0114] S5. All the above-calculated indicators are stored, and the FEV1 / FVC value and the gold standard for clinical diagnosis of COPD are used to obtain the automatic diagnosis result of COPD.

[0115] The workflow diagram of the user interactive software design for pulmonary function testing based on smartphone APP is as follows Fig.10 As shown, the specific process is as follows.

[0116] A1. When the program starts running, it enters the main interface and provides users with various visual operation buttons, including the button for connecting the Bluetooth sensor, and the start and end buttons for the lung function test. The program waits for the sensor to be connected.

[0117] A2. When the Bluetooth connection is established, the output voltage data of the thermal air flow sensor sent by the lower computer is continuously received, and the voltage is converted into an air flow value using a calibration formula. The obtained real-time air flow value is timestamped to form an air flow-time curve, and the air flow-time curve is drawn according to the air flow value and displayed in the form of a dynamic curve chart at the corresponding position on the display interface, and the air flow values ​​and corresponding time values ​​in pairs are stored in real time.

[0118] A3. When the user clicks on the pulmonary function test, the pulmonary ventilation volume-time curve in step S1 of the above-mentioned pulmonary function instrument analysis algorithm is called according to the airflow-time curve, and the ventilation volume-time curve is drawn according to the airflow value and displayed in the corresponding position on the display interface in the form of a dynamic curve chart, and the ventilation volume values ​​and corresponding time values ​​in pairs are stored in real time.

[0119] A4. When the user clicks the end button of the pulmonary function test, the pulmonary function test ends. The above-mentioned pulmonary function instrument analysis algorithm steps S2-S5 are called to obtain various indicators and COPD diagnosis conclusions according to the indicator calculation algorithm. The final values ​​of each indicator and the COPD diagnosis conclusion are displayed at the corresponding positions of the interface. A pulmonary function test process is completed.

[0120] A5. The program waits for other operations from the user.

[0121] The spirometer analysis algorithm uses a smartphone Android App as a carrier and is developed using the Java programming language based on the Android Studio integrated development environment. The spirometer analysis algorithm uses the Python programming language for simulation and debugging, and is finally integrated and deployed into the above-mentioned Android App using Java programming.

[0122] like Figure 11(a)-Figure 12(e)As shown, FIG11(a) is the main page for displaying and connecting the thermal air flow sensor data of the pulmonary function test, which is used to connect the pulmonary function instrument and display the real-time sensing data and air flow of the thermal air flow sensor. FIG11(b) and FIG11(c) are the real-time display and result analysis pages of the pulmonary function test. FIG11(b) shows the real-time air flow curve during the pulmonary function test, which is used to indicate the current blowing and inhalation of the user; and the buttons for the pulmonary function test and start, so that the user can start and end the pulmonary function test. FIG11(c) shows the analysis results after the pulmonary function test, including the flow volume ring and the data display of various pulmonary function test indicators. FIG12(a) shows the physical picture of the pulmonary function instrument. FIG12(b) shows the schematic diagram of the user using the pulmonary function instrument. FIG12(c) shows the main page for displaying and connecting the thermal air flow sensor data of the pulmonary function test in actual use, as well as the real-time sensing data and air flow of the sensor after connecting the pulmonary function instrument. FIG12(d) shows the real-time air flow curve during the pulmonary function test in actual use, which is used to reflect the current blowing and inhalation of the user. FIG12( e ) shows the analysis results after the actual pulmonary function test, including the flow volume loop and the data display of various pulmonary function test indicators.

[0123] The display interface consists of two pages. The first page integrates the connection, debugging and data display functions of the thermal air flow sensor, including two curve charts, a Bluetooth connection tab, and multiple data display icons and buttons. The second page is the core operation and display page of the pulmonary function test, which consists of 2 curve charts and several data display icons, a text output box, and 2 main buttons (the start button and the end button of the pulmonary function test). Click the start button (that is, the [Start] button) to start the pulmonary function test. The first curve chart shows the real-time volume-time change curve during the pulmonary function test. After clicking the end button (i.e., the [Done] button), the second curve chart displays the flow volume loop of the patient's pulmonary function test after algorithm analysis and generation, and the text output box displays the important indicators of the patient's pulmonary function test, including: FVC (ventilation volume / vital capacity during forced exhalation), PFE (peak airflow during forced exhalation), FEV1 (expiratory volume in the first second of forced exhalation), FEV1 / FVC, VCMAX (maximum vital capacity), MEF25 (the airflow value corresponding to the remaining 25% of the maximum expiratory volume of exhaled gas), MEF50 (the airflow value corresponding to the remaining 50% of the maximum expiratory volume of exhaled gas), MEF75 (the airflow value corresponding to the remaining 75% of the maximum expiratory volume of exhaled gas). In addition, there are some auxiliary functions, including test data download, cloud upload, clear display, etc., which are provided to users in the form of buttons.

[0124] In this embodiment, the error test of the breathing gas volume capacity uses a medical device, a spirometer calibration cylinder. The experiment uses a 3L calibration cylinder for testing, and uses an algorithm to calculate the volume measured by the spirometer, and calculates the error with 3L. The error test results are shown in Table 1.

[0125] Table 1 Error test results

[0126]

[0127] Table 2 System indicators

[0128]

[0129] Based on a certain test sample (test time 2024.11.15), the comparison results of the pulmonary function test data of the portable pulmonary function meter based on thermal flow measurement in this embodiment and other desktop pulmonary function meters are shown in Table 3.

[0130] Table 3 Comparison results of lung function test data

[0131] Index (unit) This prototype A desktop pulmonary function tester Error (relative error%) PEF(L / s) 9.11 9.62 -1.66(-5.30％) FVC(L) 4.11 4.29 -0.18(-4.20％) FEV1(L) 3.25 3.48 -0.23(-6.61％) FEV1 / FVC 78.38％ 81％ -2.62％(-3.23％) MEF25(L / s) 1.5 1.45 +0.05(+3.45％) MEF50(L / s) 3.25 3.64 -0.39(-10.7％) MEF75(L / s) 7.44 7.46 -0.02(-0.27％)

[0132] Example 2

[0133] This embodiment provides a lung function monitoring method, which is implemented using the portable lung function meter based on thermal flow measurement described in Example 1. The lung function measurement method includes:

[0134] Obtaining air flow-time curve;

[0135] Numerically integrating the airflow-time curve along the time axis to obtain a pulmonary ventilation volume-time curve;

[0136] Dividing the airflow-time curve into a plurality of breathing cycles, wherein each breathing cycle includes a complete process of exhalation and inhalation;

[0137] Obtaining a flow-volume graph according to the airflow-time curve and the pulmonary ventilation volume-time curve corresponding to each respiratory cycle;

[0138] The characteristic data of the user's lung function test are extracted according to the airflow-time curve and the flow-volume diagram corresponding to each breathing cycle.

[0139] The implementation scheme for solving the problem provided by the lung function monitoring method in this embodiment is similar to the implementation scheme recorded in the lung function meter analysis algorithm in Example 1, so it will not be repeated here.

[0140] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0141] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A portable pulmonary function instrument based on thermal flow measurement, characterized in that: The portable pulmonary function instrument based on thermal flow measurement comprises: Sensor components, hardware circuits, microcontrollers, and clients; The sensor component is connected to the microcontroller via the hardware circuit; The microcontroller is in communication connection with the client; The sensor assembly is used to collect airflow data, wherein the sensor assembly is a thermal airflow sensor, the thermal airflow sensor comprises an airflow sensor chip and a flow channel, the flow channel comprises a main airflow flow channel and a bypass airflow flow channel, the airflow sensor chip is packaged in the bypass airflow flow channel, the cross-sectional area of ​​the main airflow flow channel and the cross-sectional area of ​​the bypass airflow flow channel satisfy a preset area ratio, and the cross-sectional area of ​​the bypass airflow flow channel is smaller than the cross-sectional area of ​​the main airflow flow channel; The microcontroller is used to obtain an airflow-time curve according to the airflow data; The client is used to extract characteristic data of the user's lung function test according to the airflow-time curve.

2. The portable pulmonary function meter based on thermal flow measurement according to claim 1, characterized in that: The hardware circuit includes a sensor readout bridge, a voltage amplification circuit and an ADC sampling module connected in sequence; The sensor readout bridge is connected to the sensor assembly; The ADC sampling module is connected to the microcontroller; The sensor readout bridge circuit is used to convert the air flow data into a voltage signal; The voltage amplifier circuit is used to perform differential amplification and noise reduction processing on the voltage signal to obtain an amplified and noise-reduced voltage signal; The ADC sampling module is used to perform analog-to-digital conversion on the amplified and noise-reduced voltage signal to obtain a digital signal.

3. The portable pulmonary function meter based on thermal flow measurement according to claim 2, characterized in that: The hardware circuit also includes: a temperature compensation module; The temperature compensation module is respectively connected to the sensor assembly and the sensor readout bridge circuit; The temperature compensation module is used to monitor the temperature change of the sensor component in real time and adjust the voltage signal according to the temperature change.

4. The portable pulmonary function meter based on thermal flow measurement according to claim 1, characterized in that: The characteristic data include: vital capacity during forced exhalation, peak air flow during forced exhalation, expiratory volume in the first second of forced exhalation, maximum vital capacity, air flow value corresponding to the remaining 25% of the maximum expiratory volume of exhaled gas, air flow value corresponding to the remaining 50% of the maximum expiratory volume of exhaled gas, air flow value corresponding to the remaining 75% of the maximum expiratory volume of exhaled gas, and ratio, wherein the ratio is the ratio of the expiratory volume in the first second of forced exhalation to the vital capacity during forced exhalation.

5. The portable pulmonary function meter based on thermal flow measurement according to claim 1, characterized in that: The client includes a pulmonary ventilation volume-time curve generation module, a data preprocessing module, a flow volume map generation module and a feature calculation module; The pulmonary ventilation volume-time curve generation module is used to numerically integrate the airflow volume-time curve along the time axis to obtain the pulmonary ventilation volume-time curve; The data preprocessing module is used to divide the airflow-time curve into a plurality of breathing cycles, wherein each breathing cycle includes a complete process of exhalation and inhalation; The flow volume graph generation module is used to obtain a flow volume graph according to the air flow-time curve and the pulmonary ventilation volume-time curve corresponding to each respiratory cycle; The feature calculation module is used to extract feature data of the user's lung function test based on the airflow-time curve and flow-volume diagram corresponding to each breathing cycle.

6. A method for monitoring lung function, characterized in that: The pulmonary function measurement method is implemented using the portable pulmonary function meter based on thermal flow measurement according to any one of claims 1 to 5, and the pulmonary function measurement method comprises: Obtaining air flow-time curve; Numerically integrating the airflow-time curve along the time axis to obtain a pulmonary ventilation volume-time curve; Dividing the airflow-time curve into a plurality of breathing cycles, wherein each breathing cycle includes a complete process of exhalation and inhalation; Obtaining a flow-volume graph according to the airflow-time curve and the pulmonary ventilation volume-time curve corresponding to each respiratory cycle; The characteristic data of the user's lung function test are extracted according to the airflow-time curve and the flow-volume diagram corresponding to each breathing cycle.

7. The lung function monitoring method according to claim 6, characterized in that: The characteristic data include: vital capacity during forced exhalation, peak air flow during forced exhalation, expiratory volume in the first second of forced exhalation, maximum vital capacity, air flow value corresponding to the remaining 25% of the maximum expiratory volume of exhaled gas, air flow value corresponding to the remaining 50% of the maximum expiratory volume of exhaled gas, air flow value corresponding to the remaining 75% of the maximum expiratory volume of exhaled gas, and ratio, wherein the ratio is the ratio of the expiratory volume in the first second of forced exhalation to the vital capacity during forced exhalation.

8. The lung function monitoring method according to claim 7, characterized in that: The vital capacity during forced exhalation and the peak airflow during forced exhalation are variable values ​​obtained by numerically integrating the expiratory airflow-time curve along the time axis, wherein the expiratory airflow-time curve is an airflow-time curve corresponding to the expiratory part in each breathing cycle.

9. The lung function monitoring method according to claim 7, characterized in that: The airflow value corresponding to the remaining 25% of the maximum expiratory volume of the exhaled gas is the expiratory airflow corresponding to the volume of (1-25%) of the maximum expiratory lung volume on the flow-volume diagram.

10. The lung function monitoring method according to claim 7, characterized in that: The airflow value corresponding to the remaining 50% of the maximum expiratory volume of the exhaled gas is the expiratory airflow corresponding to the volume of (1-50%) of the maximum expiratory lung volume on the flow-volume diagram; the airflow value corresponding to the remaining 75% of the maximum expiratory volume of the exhaled gas is the expiratory airflow corresponding to the volume of (1-75%) of the maximum expiratory lung volume on the flow-volume diagram.

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