A spirometry device based on optical fiber sensing and a detection method thereof

Abstract

A kind of spirometry based on optical fiber sensing and its detection method, the device includes medium flow pipe, the upper end of the medium flow pipe is provided with blowing port, the lower end of the medium flow pipe is provided with gas outlet, the medium flow pipe is opened with the through hole that internal aperture is communicated, the through hole is blocked with FBG (fiber bragg grating) sensor, the FBG sensor is connected with demodulator;The present application has the advantages that lung capacity is accurately detected based on FBG technology, and the sensitivity and precision of detection are higher.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of vital capacity detection, and particularly relates to a vital capacity detection device based on fiber-optic sensing and a detection method thereof. BACKGROUND

[0002] Vital capacity reflects the potential capacity of respiratory function. Through the measurement of vital capacity, the strength of human respiratory capacity can be obtained, and the decline degree of respiratory capacity after disease recovery and the ability to engage in labor tasks can be judged.

[0003] In daily life, devices with air pressure sensors or gas flow sensors are mainly used to measure vital capacity. After long-term use, these sensors will gradually age, and there is a possibility of generating a large error due to the absence of a self-calibration component. In addition, due to the low sensitivity of these two sensors, a relatively weak exhalation behavior may not be able to be detected, resulting in the suspension of the cumulative value of vital capacity on the instrument. This will result in the vital capacity of some patients with lung diseases being unable to be measured, in addition, the blowing method of the user greatly affects the detection result, resulting in poor reliability of the detection result of this kind of sensor. Some simple instruments (such as instruments based on the principle of water displacement) can be used for vital capacity detection in this case, but the use process is relatively cumbersome, and the obtained result is relatively not intuitive.

[0004] In order to improve the corresponding exhalation value of vital capacity measurement, some designs have also been proposed in other research projects: solid-state sensors using ionization principle can correspond to air flow speed as low as 1.8 m / s, with high sensitivity. However, the material for manufacturing this measurement device needs to be considered to prevent static electricity from occurring. In addition, the sensor needs to be completely dried before the next use.

[0005] Another instrument using non-contact electrode resistance impedance principle has a measurement frequency of 100 kHz, which is embedded in clothing (such as a shirt), which has the advantage of testing at any time in daily life. However, if the entire exhalation process is artificially interrupted for a short period of time and then continued, the device will generate a large error. This defect will affect the vital capacity measurement results of some patients with lung diseases.

[0006] There is also a wearable device using electrical impedance tomography technology, which can keep the data record stable if the patient artificially interrupts a small exhalation process during the measurement process; however, the wearing process of the device is relatively troublesome, and it is difficult to meet the convenient needs of patients for daily vital capacity monitoring. SUMMARY

[0007] The application provides a vital capacity detection device based on FBG technology to accurately detect vital capacity, which has higher sensitivity and accuracy.

[0008] In order to solve the above technical problems, the technical scheme adopted by the present application is: a kind of based on optical fiber sensing vital capacity detection device, the device includes medium flow pipe, the upper end of the medium flow pipe is provided with blowing port, the lower end of the medium flow pipe is provided with gas outlet, the medium flow pipe is opened with the through hole that internal aperture is communicated, the through hole is blocked with FBG (optical fiber Bragg grating) sensor, the FBG sensor is connected with demodulator.

[0009] With the above structure, the vital capacity detection device of the present application introduces FBG (optical fiber Bragg grating) sensor, FBG is installed on the medium flow pipe, in the experiment process, sensor will reflect and output the center wavelength of FBG to demodulator in real time, and the experimenter will obtain the waveform graph of the cumulative change of center wavelength with time in the process of recording breathing after signal processing, realize that only FBG sensor is carried to independently derive vital capacity test result;Since FBG sensor has high sensitivity, it can finely reflect the pressure and temperature change of its surface, and by extracting and processing the surface pressure change information, more accurate and precise vital capacity value can be obtained.

[0010] Further, the medium flow pipe includes first flow pipe and second flow pipe connected with each other, the blowing port is located at the pipe opening of the first flow pipe, and the FBG sensor is located on the second flow pipe;With the structure, blowing can flow through the first flow pipe first, and then enter the second flow pipe to form more stable blowing airflow, so as to realize more accurate detection.

[0011] Further, the internal aperture of the first flow pipe is larger than that of the second flow pipe;With the structure, the gas flow passes through the large aperture first, and then flows into the small aperture, which can increase the gas pressure in the pipe to increase the sensitivity of FBG sensor detection.

[0012] Further, the FBG sensor is wrapped with protective film, and the protective film is used for heat insulation and water isolation of the FBG sensor;With the above structure, the FBG sensor can be protected, to prevent false positive or false negative of detection result caused by overheating or water contact of FBG sensor.

[0013] Further, the FBG sensor is provided with at least two, and one of them is close to blowing port, and the other is located at the middle position of the second flow pipe, which can carry out multi-point synchronous detection on the airflow in the medium flow pipe, and improve the detection accuracy.

[0014] Further, the FBG sensor is provided with three, and one of them is close to the blowing port, one is close to the outlet, and the other is located in the second flow pipe close to the middle position; The extension direction of the two FBG sensors close to the blowing port and the outlet is consistent; With the above structure, the sensor signal amplitude of the two positions close to the blowing port is larger, and the FBG sensor placed close to the outlet can be used to detect the volume and temperature change of water vapor, which can be used for system variable (temperature, water vapor) calibration.

[0015] Further, the tail end of the second flow pipe is provided with a water vapor collection port, which is sealed in the blowing state; With this structure, after accumulating a certain amount of water vapor, the water vapor is drained, avoiding long-term retention of water vapor in the device to cause pollution, and also avoiding the direct outflow of water vapor.

[0016] Further, the medium flow pipe is provided with a counterweight, and the medium flow pipe is inclined on the counterweight; With this structure, the counterweight can increase the stability of the detection device in the detection process, and will not easily displace to affect the accuracy of detection; The inclined medium flow pipe can be adapted to the blowing posture of the human body.

[0017] The application also provides a detection method using the above-mentioned fiber-optic-sensor-based spirometry detection device, specifically including:

[0018] (1) The tester first uses a spirometer (WQS-20000, existing commercial tester) to test and obtain the first set of spirometry data;

[0019] (2) After the collection is completed, the tester needs to sit still for 1-5 minutes;

[0020] (3) The tester uses the fiber-optic-sensor-based spirometry detection device (i.e. the detection device of the application) connected with the spirometer to perform the second round of spirometry test;

[0021] (4) After the collection is completed, the tester needs to sit still for 1-5 minutes;

[0022] (5) Repeat steps (1)-(4) 3-6 times to complete the experimental data collection.

[0023] Further, the lung capacity testing instrument connected to the lung capacity detection device based on optical fiber sensing (i.e., the detection device of the present application) described in step (3) is used for lung capacity detection, and the interval between every two adjacent lung capacity detections is 1.5-2 minutes; the instrument needs 1.5-2 minutes of cooling time after the end of one lung capacity, and the signal change of the sensor is affected by two factors, temperature and gas pressure; the gas pressure corresponds to the lung capacity, and the temperature corresponds to the temperature difference between the room temperature and the exhaled gas. The sensor is cooled to room temperature after each detection to ensure the accuracy of the next detection, because each detection signal will be analyzed comprehensively due to the influence of temperature and gas pressure, so as to separate the signal corresponding to the gas pressure; the cooling time refers to the time required for the surface temperature of the FBG sensor to cool from the temperature of the exhaled gas to room temperature.

[0024] Further, the lung capacity testing instrument connected to the lung capacity detection device based on optical fiber sensing (i.e., the detection device of the present application) described in step (3) is used for lung capacity detection, and the interval between every two adjacent lung capacity detections is 1.5-2 minutes; the instrument needs 1.5-2 minutes of cooling time after the end of one lung capacity, and the signal change of the sensor is affected by two factors, temperature and gas pressure; the gas pressure corresponds to the lung capacity, and the temperature corresponds to the temperature difference between the room temperature and the exhaled gas. The sensor is cooled to room temperature after each detection to ensure the accuracy of the next detection, because each detection signal will be analyzed comprehensively due to the influence of temperature and gas pressure, so as to separate the signal corresponding to the gas pressure; the cooling time refers to the time required for the surface temperature of the FBG sensor to cool from the temperature of the exhaled gas to room temperature.

[0025] The advantages and beneficial effects of the present application are:

[0026] 1. The detection method of the present application is used to evaluate the relationship between the signal recorded by the FBG sensor during the experiment and the lung capacity of the tester, and the strength, amplitude, duration and other characteristics of the exhalation process can be reflected by the curve of the shift amount of the FBG center wavelength: when stopping exhalation, the curve will quickly decrease, and this feature can be used as a sign of exhalation interruption / exhalation stop, and when blowing again for a short time, the curve will quickly rise for a short time to return to a flat and jittering state; because the present method can dynamically monitor the whole process of measuring lung capacity through the setting of FBG, it can identify different states in the exhalation process, so as to more accurately test the lung capacity; the existing electronic principle spirometer gives different results for the same lung capacity with different blowing methods (blowing speed), so it is not stable enough; the method of the present application can record the whole process of measuring lung capacity with different blowing characteristics with smaller error.

[0027] 2. The method of the present application connects the existing mature commercial spirometer with the spirometer based on optical fiber sensing in series. In the specific detection process, the same tester has a large change in the size of the lung capacity corresponding to each blow: for example, the first test is 3500 ml, and the second test is 4000 ml. If not connected in series, the corresponding relationship between the lung capacity value blown by the tester based on the optical fiber sensing spirometer and the detection result of the commercial spirometer cannot be known, and it is also difficult to interpret the FBG center wavelength shift curve of the test result. After connection, the specific size relationship of each blow (directly read by the commercial spirometer connected in series) can be obtained to help calculate the lung capacity result obtained by the FBG center wavelength shift. Through the connection method, the tester's breath can be collected by the existing equipment and the self-made equipment at the same time, which is convenient for comparing the detection results of the two devices. In addition, although the existing commercial spirometer can continuously test the lung capacity of the tester, it cannot be integrated with other medical devices and cannot test multiple indicators. The respiratory monitoring device being studied can test more indicators at the same time.

[0028] 3. Three FBG sensors are arranged at three specific positions of the spirometer based on optical fiber sensing of the present application. The two positions close to the blow port have a large signal amplitude according to experience, and the bottom is mainly used to collect water vapor. The FBG can also be placed to detect the volume and temperature change of the water vapor, but it is not mainly used for lung capacity test. The function is used for system variable (temperature, water vapor) calibration.

[0029] 4. The FBG sensor of the present application is wrapped with a protective film, which can reduce the influence of temperature and water vapor on the FBG. Although the signal change amplitude will be reduced to some extent, the signal change caused by the air pressure brought by the tester blowing with different lung capacity will be reduced, and the judgment of lung capacity will not be affected. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The first view of the structure of the spirometer based on optical fiber sensing of the present application.

[0031] Figure 2 The second view of the structure of the spirometer based on optical fiber sensing of the present application.

[0032] Figure 3 The structure of the spirometer based on optical fiber sensing of the present application is shown in the cross-sectional view.

[0033] Figure 4 The structure of the spirometer based on optical fiber sensing of the present application is connected with the demodulator.

[0034] Figure 5The integral results of the algorithm were compared with the results of a spirometer connected to the self-made instrument.

[0035] Figure 6 The image of the center wavelength shift with time due to the delay of FBG response.

[0036] As shown in the drawings: 1. medium flow pipe, 101. air inlet, 102. air outlet, 103. internal aperture, 104. through hole, 105. first flow pipe, 106. second flow pipe, 107. water vapor collection port, 2. FBG (Fiber Bragg Grating) sensor, 3. demodulator, 4. counterweight. DETAILED DESCRIPTION

[0037] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the embodiments and drawings. Obviously, the described embodiments are only preferred embodiments, but not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0038] In addition, it should be noted that when a component is referred to as being "fixed" to another component, it can be directly on the other component or can be fixed thereto through another intermediate component. When a component is referred to as being "connected" to another component, it can be directly connected to the other component or can be connected thereto through another intermediate component. When a component is referred to as being "disposed" on another component, it can be directly disposed on the other component or can be disposed thereon through another intermediate component. The terms "vertical", "horizontal", "left", "right", and the like used herein are for illustrative purposes only. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0039] As shown in the drawings: Figures 1-4As shown, it is a kind of spirometry based on optical fiber sensing of the application, the device includes medium flow pipe 1, the upper end of the medium flow pipe 1 is provided with blowing port 101, the lower end of the medium flow pipe 1 is provided with gas outlet 102, the medium flow pipe 1 is provided with through hole 104 communicated with internal aperture 103, the through hole 104 is blocked with FBG (fiber Bragg grating) sensor 2, the FBG sensor 2 is connected with demodulator 3 (the above connection can transmit the signal obtained by FBG sensor to demodulator, and the demodulator is connected with computer and other data collection and storage equipment, and the data is transmitted to computer for collection and processing).

[0040] With the above structure, the spirometry of the application introduces FBG (fiber Bragg grating) sensor, and the fiber grating sensor is installed on the medium flow pipe. In the experiment, the sensor can reflect and output the offset result of FBG center wavelength to the demodulator in real time. The experimenter will get the waveform graph of the change of center wavelength with time after signal processing, and realize that the spirometry test result can be obtained independently under the condition of only carrying FBG sensor. Because FBG sensor has high sensitivity, it can finely reflect the change of pressure and temperature on its surface. By extracting and processing the surface pressure change information, more accurate and precise spirometry value can be obtained.

[0041] As shown in the accompanying Figures 1-4 The medium flow pipe 1 of the application includes first flow pipe 105 and second flow pipe 106 connected with each other, the blowing port 101 is located at the pipe opening of the first flow pipe 105, and the FBG sensor 2 is located on the second flow pipe 106. With this structure, the blowing first flows through the first flow pipe and then enters the second flow pipe to form more stable blowing airflow, realizing more accurate detection.

[0042] As shown in the accompanying Figure 3 The internal aperture of the first flow pipe 105 of the application is larger than that of the second flow pipe 106. That is, the medium flow pipe of the application is a hollow pipe structure with axial through hole, and the size of the internal hollow aperture is different. With this structure, the airflow first passes through the large aperture and then flows into the small aperture. This way can improve the pressure change in the pipe to increase the sensitivity of FBG sensor detection.

[0043] As an example, the ratio of the axial length of each of the first flow tube 105 and the second flow tube 106 is not limited, but the axial length of the first flow tube is designed to ensure that a distance is left after the installation of the spirometer mouthpiece (a mouthpiece is arranged at the blowing port position to facilitate the adaptation with the human mouth and facilitate blowing); the axial length of the second flow tube is designed to ensure that a large enough dynamic pressure difference is formed at different positions where the FBG sensor is arranged; the ratio of the size of each tube diameter is not limited, but the tube diameter of the first flow tube is more than 2-3 times the tube diameter of the second flow tube to increase the flow speed of the gas in the self-made instrument.

[0044] As an example, the FBG sensor 2 described in the present application is wrapped with a protective film, which is used for heat and water insulation of the FBG sensor; the protective film can be a transparent adhesive tape in the prior art, which fully wraps the FBG sensor, and two layers (one layer is arranged on each of the two opposite surfaces along the thickness direction of the long sensor, and the two outer layers are bonded with each other to completely wrap the sensor), the inner layer is in contact with the inner diameter of the medium flow tube for sensing the gas flow and isolating water vapor, and the outer layer can isolate ambient air; by using the above structure, the FBG sensor can be protected, and false positive or false negative of the detection result of the FBG sensor caused by overheating or contact with water can be prevented; the position where the sensor is arranged is also sealed to prevent gas leakage from these places; the influence of temperature and water vapor on the FBG can be minimized (the sensitivity will not change).

[0045] As an example, the FBG sensor 2 described in the present application is arranged at least two, and one of them is close to the blowing port 101, and the other is located at a position close to the middle of the second flow tube 106 (i.e. the position 104 in the figure), which can perform multi-point synchronous detection on the blowing in the medium flow tube and improve the accuracy of detection.

[0046] As an example, as shown in the accompanying Figures 1-4 As an example, as shown in the accompanying

[0047] The FBG sensors of the application, when the number is two or more, are connected in series with each other on the same optical fiber, and then connected with the demodulator; the demodulator of the application is finally connected with a device capable of realizing data transmission, storage and processing, such as a computer.

[0048] As shown in the accompanying drawings Figure 1 As shown in the accompanying drawings

[0049] As shown in the accompanying drawings Figures 1-4 As shown in the accompanying drawings

[0050] The following specifically describes a specific method for detecting the vital capacity by using the vital capacity detection device based on the optical fiber sensing described above:

[0051] The application also provides a detection method using the vital capacity detection device based on the optical fiber sensing, which specifically comprises:

[0052] (1) The tester first uses a vital capacity tester (WQS-20000) to test and obtain a first set of vital capacity data (existing commercial vital capacity tester);

[0053] (2) After the collection is completed, the tester needs to sit still for 1 minute;

[0054] (3) The tester uses the vital capacity detection device connected with the vital capacity tester to perform a second round of vital capacity test;

[0055] (4) After the collection is completed, the tester needs to sit still for 1 minute;

[0056] (5) Steps (1)-(4) are repeated four times to complete the collection of experimental data.

[0057] Main results:

[0058] Table 1. Experimental results (ml)

[0059]

[0060] From the above detection data, the test results of the connected spirometer and the test results of the spirometry device based on fiber sensing have a certain degree of correlation; through the comparative experiment, the attenuation ratio of the connected lung capacity is obtained, and the FBG center wavelength shift curve is interpreted by the attenuated lung capacity, the attenuated lung capacity is judged from the curve, and the actual lung capacity without attenuation is calculated through the proportional attenuation relationship. In the second group of experiments, the lung capacity tester is connected with the self-made instrument (the interface is fixed by hot melt adhesive to prevent air leakage), and the pressure sensor in the lung capacity tester feels smaller pressure during blowing, the scale is smaller, and the center wavelength shift curve of the FBG (air outlet) close to the lower side is more stable.

[0061] As shown in the accompanying drawings Figure 5 The FBG data processing and integral results of the self-made instrument for each time of lung capacity test correspond to the test results of the connected lung capacity tester each time, and are sorted according to the test results of the connected lung capacity tester: the lung capacity test results obtained by the above 25 groups in series are arranged from low to high, the integral results of the algorithm according to the FBG center wavelength change curve are blue, the abscissa represents the volunteer number, and the lung capacity values detected by the existing equipment are sorted; the detection instrument of the application obtains the offset of the FBG center wavelength through the demodulator, draws the FBG center wavelength shift curve according to the offset in a period of exhalation experiment, and comprehensively analyzes the curvature, amplitude and integral of the curve to calculate the lung capacity.

[0062] Table 2 V = 10 m / s

[0063] Name Current Value Progress Standard Average SG Average Dynamic Pressure 1 401.026 Pa Reached (IT=121) 10.0096 Pa 994.032 Pa SG Average Dynamic Pressure 2 882.052 Pa Reached (IT=89) 16.5138 Pa 884.133 Pa SG Average Velocity 3 19.6177 m / s Reached (IT=119) 0.538622 m / s 19.2629 m / s SG Average Velocity 4 31.661 m / s Reached (IT=89) 0.378983 m / s 31.6513 m / s SG Average Velocity 5 10.0082 m / s Reached (IT=65) 0.000218793 m / s 10.0082 m / s

[0064] Table 3 V = 12.5 m / s

[0065] Name Current Value Progress Standard Average SG Average Dynamic Pressure 1 674.686 Pa Reached (IT=122) 17.4083 Pa 662.106 Pa SG Average Dynamic Pressure 2 1452.69 Pa Reached (IT=91) 26.9941 Pa 1452.77 Pa SG Average Velocity 3 25.6245 m / s Reached (IT=120) 0.73107 m / s 24.7435 m / s SG Average Velocity 4 40.4099 m / s Reached (IT=91) 0.467904 m / s 40.41 m / s SG Average Velocity 5 12.509 m / s Reached (IT=64) 0.00022581 m / s 12.509 m / s

[0066] Table 4 V = 15 m / s

[0067] Name Current Value Progress Standard Average SG Average Dynamic Pressure 1 1121.78 Pa Reached (IT=118) 27.2141 Pa 1110.27 Pa SG Average Dynamic Pressure 2 2286.01 Pa Reached (IT=89) 44.9141 Pa 2299.7 Pa SG Average Velocity 3 50.4791 m / s Reached (IT=116) 0.911945 m / s 32.1934 m / s SG Average Velocity 4 32.8202 m / s Reached (IT=87) 0.558064 m / s 50.6037 m / s SG Average Velocity 5 15.0069 m / s Reached (IT=67) 7.47195e-05 m / s 15.0069 m / s

[0068] Table 5 V = 17.5 m / s

[0069] Name Current Value Progress Standard Average SG Average Dynamic Pressure 1 1766.14 Pa Reached ((T=92) 44.7075 Pa 3502.68 Pa SG Average Dynamic Pressure 2 3513.59 Pa Reached (IT=79) 75.4259 Pa 3502.68 Pa SG Average Velocity 3 40.3413 m / s Reached ((T=90) 1.14605 m / s 43.0455 m / s SG Average Velocity 4 62.1131 m / s Reached (IT=81) 0.764278 m / s 62.0456 m / s SG average value Velocity 5 17.4989 m / s Reached (IT = 53) 0.00034904 m / s 17.4989 m / s

[0070] Table 6 V = 20 m / s

[0071]

[0072]

[0073] The above Table 2-6 is the use of Flow Simulation in Solidworks to apply different blowing speed to the blowing port of the self-made device (not in series with commercial spirometry) under water-tight conditions, the air flow speed and the dynamic pressure value of the position of the two FBG sensors. In the iterative algorithm of Flow Simulation, "Name": the name given by the test target at different sites. "Current value": the dynamic pressure / speed value solved at the current corresponding iteration number. "Progress": the progress of the value iteration completion. "Criteria": stop criteria. In the standard grid, choose one (i.e., once one of the following conditions is met, the calculation is automatically completed) or all (i.e., once all the following conditions are met, the calculation is automatically completed). If the amplitude deviation (increment) of the target during the analysis interval is less than the target convergence criteria automatically determined by Flow Simulation after the start of calculation or manually specified in the calculation control options dialog box, the target is considered to be converged. Average-Table value of the target average value within the analysis interval; speed 3 in the table is the blowing speed of the FBG position close to the air outlet position, speed 4 is the blowing speed of the FBG position close to the blowing port position, and speed 5 is the blowing speed applied in the direction of the blowing port (blowing port position). As the speed 5 (simulated blowing speed) increases, the speed 4 (FBG sensor placement position close to the blowing port, dynamic pressure 2) and the speed 3 (FBG sensor placement position away from the blowing port, dynamic pressure 1) also increase in a multiple type of positive relationship. And the blowing speed represented by speed 4 is always greater than the blowing speed represented by speed 3.

[0074] From the above Table 2-6 and the attached Figure 6 The results show that when the blowing speed is large, the pressure felt by the FBG will be larger, the center wavelength curve will rise faster in the initial stage, and will remain stable in a higher center shift area. When the blowing speed is small, the pressure felt by the FBG will be smaller, the center wavelength curve will rise slower in the initial stage, and will remain stable in a lower center shift area.

[0075] The above simulation shows the pressure changes caused by different blowing speeds at different pressure sensing ports inside the tube under the water-tight internal structure. In the real experiment, port A (air outlet 102) will be connected to the commercial spirometer to display the spirometry data positively correlated with the real spirometry to calibrate the algorithm results. Although the total gas flow cavity volume and shape have changed, the pressure size through the self-made instrument is still expected to have a positive correlation with the blowing speed, and there is a pressure difference between the two pressure sensing ends.

[0076] As shown in the attached Figure 6The algorithm-derived integral result "here the algorithm specifically determines the dynamic exhalation flow rate at the FBG center wavelength shift graph after evaluating and compensating the exhalation flow temperature. The gas flow rate represented by the graph is integrated to determine the size of the testee's vital capacity" is consistent with the results displayed by the vital capacity tester connected to the self-made instrument. Due to the delay of FBG response, the center wavelength shift graph over time is analyzed as follows: during the initial blowing (rising phase) pressure, the response is not good, and compensation should be made by combining the slope and the holding phase to obtain the cumulative blowing amount during this phase; during the relatively stable blowing phase, the pressure generated by the airflow can be well responded by the sensor to enter the signal holding phase, and the testee is in the force stage, which has a greater impact on the instrument's jitter, and compensation should be made by combining different sensors at different sites. Figure 6 The blue line in the graph represents the center wavelength shift recorded by the FBG installed near the blowing port (dynamic pressure 2, speed 4 corresponding position) during a single vital capacity test at different time periods. The red line represents the center wavelength shift curve of the FBG near the air outlet (dynamic pressure 1, speed 3 corresponding position) during a single vital capacity test at different time periods.

[0077] Based on the above test data and test results, the following main conclusions are drawn: the results obtained by the algorithm show that the integral size of the FBG center wavelength shift value in the large trend has a positive correlation with the results displayed by the vital capacity tester connected to the self-made instrument; however, individual value comparison shows that the results obtained by the algorithm need to be further refined; in addition, the integral growth trend of values above 3000 (corresponding to real vital capacity above 3800) is significantly different from that below 2500, which may be caused by algorithm accuracy, but it is more likely caused by the detection error of commercial equipment itself for different vital capacities and blowing methods.

[0078] Current defects:

[0079] 1. The current number of test samples is limited, and the relationship between the integral results of the algorithm and the algorithm for more vital capacity intervals (real value 1000-2000, 5000-6000…) is not provided.

[0080] 2. High vital capacity volunteers (generally with longer blowing time) unintentionally weaken the blowing intensity during the blowing process, resulting in an additional time that is not reduced by the algorithm but causes the commercial equipment detection value to be low. The data of the FBG located at the upper end of this use (closer to the vibration source) will be processed synchronously to distinguish between larger vibrations and the decay and stop of exhalation. And realize the recording of the whole section of the vital capacity measurement process with small pauses to further meet the medical needs.

[0081] The detection of the above-mentioned numerical value of the application, and the comparison and correlation analysis with the detection data of the existing spirometer, show that the device scheme for detecting the lung capacity by setting the FBG is feasible, and the sensitivity and accuracy of the detection are high, providing a new detection method for the detection of the existing lung capacity; The advantages of the instrument are that it can be integrated with other instruments using FBG sensors (the tail ends of FBG are connected to the same demodulator), and in health monitoring, different data can be quickly summarized and synchronously detected, facilitating comprehensive judgment of the health status of patients. In addition, the sensing technology based on the FBG technology can effectively avoid the defects of electronic equipment; and the application is measured by the optical fiber Bragg grating measurement method, which is a non-electric measurement method and does not produce electric sparks and is not disturbed by external electromagnetic signals, so the system is more stable.

Claims

1. A lung capacity detection device based on fiber optic sensing, characterized in that: The device includes a medium flow tube with an air inlet at its upper end and an air outlet at its lower end. A through-hole communicating with the internal aperture is formed in the medium flow tube, and an FBG sensor is sealed in the through-hole. The FBG sensor is connected to a demodulator. The medium flow tube comprises a first flow tube and a second flow tube connected to each other. The air inlet is located at the opening of the first flow tube, and the FBG sensor is located on the second flow tube. The internal aperture of the first flow tube is larger than that of the second flow tube. The FBG sensor is covered with a protective film for heat insulation and water resistance. At least two FBG sensors are provided, one near the air inlet and the other near the middle of the second flow tube.

2. The pulmonary capacity detection device based on fiber optic sensing according to claim 1, characterized in that: The aforementioned FBG sensor is provided in three parts, with one near the air inlet, one near the air outlet, and one located near the middle of the second flow tube; the two FBG sensors near the air inlet and the air outlet extend in the same direction.

3. The pulmonary capacity detection device based on fiber optic sensing according to claim 1, characterized in that: The tail end of the second flow pipe is provided with a water vapor collection port, which is sealed when the air is being blown.

4. The pulmonary capacity detection device based on fiber optic sensing according to claim 1, characterized in that: The medium flow pipe is provided with a counterweight, and the medium flow pipe is inclined on the counterweight.

5. A detection method using the fiber optic sensing-based vital capacity detection device according to any one of claims 1-4, characterized in that: Specifically, it includes: (1) The tester first uses a spirometer to obtain the first set of spirometer data; (2) After the collection is completed, the test subject should sit quietly for 1-5 minutes; (3) The tester used a fiber optic sensing-based lung capacity detection device connected to the lung capacity tester to conduct a second round of lung capacity testing. (4) After the collection is completed, the test subject should sit quietly for 1-5 minutes; (5) Repeat steps (1)-(4) 3-6 times to complete the experimental data collection.

6. The detection method using a fiber optic sensing-based lung capacity detection device according to claim 5, characterized in that: Lung capacity is measured using a fiber optic sensing-based lung capacity detection device connected to the lung capacity tester described in step (3), with an interval of 1.5-2 minutes between each two adjacent lung capacity measurements.

7. The detection method using a fiber optic sensing-based lung capacity detection device according to claim 5, characterized in that: The spirometry tester connected to the fiber optic sensing-based spirometry detection device specifically involves connecting the spirometry tester in series with the air outlet of the fiber optic sensing-based spirometry detection device, thereby achieving series connection between the spirometry tester and the fiber optic sensing-based spirometry detection devices.

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