CN113679374A - Main flow type expiratory carbon dioxide concentration and respiratory flow detection device and method - Google Patents
Main flow type expiratory carbon dioxide concentration and respiratory flow detection device and method Download PDFInfo
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- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 75
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 75
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Abstract
The invention discloses a mainstream type expiratory carbon dioxide concentration and respiratory flow detection device and method, which can be widely applied to the field of bioengineering medicine. The detection device comprises: the fluid passage comprises an inlet section, a detection section and an outlet section, the inlet section is used for being connected with a breathing mask, the outlet section is used for being connected with an exhalation pipeline, the detection section is provided with a first optical detection window and a second optical detection window, and a turbine rotor is arranged in the detection section; the flow sensing unit is arranged on the first optical detection window; the carbon dioxide sensing unit is arranged on the second optical detection window; and the processing unit is respectively connected with the flow sensing unit and the carbon dioxide sensing unit. The invention can improve the synchronism of the detection process and avoid the problems of signal delay and monitoring curve distortion caused by a bypass flow type sampling mode.
Description
Technical Field
The invention relates to the field of bioengineering medicine, in particular to a device and a method for detecting the concentration of carbon dioxide and respiratory flow of mainstream expired air.
Background
From the analysis of human physiology, the tissue cells of human body generate the oxidation during the metabolismCarbon, CO, which is diffused to lung bubbles through the pulmonary artery via the systemic circulation venous blood flow of the human body through gas exchange and then is discharged out of the body through the expiration of the human body2The flow direction of (1) is a diffusion process of which the gas partial pressure is from high to low. CO in human body exhalation2The content of (A) can reflect the cardiac output and arterial blood flow to a certain extent, and simultaneously the CO in the body2The levels also reflect to some extent the physiological state of the human body. The human body expiratory carbon dioxide concentration curve has obvious respiratory rhythm characteristics, is the sixth basic vital sign in clinical application at present, and is widely applied to clinical application in continuous non-invasive expiratory carbon dioxide concentration monitoring. Expiratory flow is also a very intuitive index for evaluating lung function, and directly reflects the lung function level of a subject. In applications such as rehabilitation medicine and cardio-pulmonary function evaluation, expiratory carbon dioxide and expiratory flow are also main monitoring indexes. In the related art, when the index monitoring is performed by the existing medical equipment, an independent carbon dioxide sensor and a flow sensor are generally used for monitoring, and a difference between main flow sampling and side flow sampling also exists in a sampling mode. This results in an uncertain delay between the monitored carbon dioxide concentration and the expiratory flow and a distortion of the monitoring curve.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a main flow type expiratory carbon dioxide concentration and respiratory flow detection device and method, which can effectively avoid the problems of signal delay and monitoring curve distortion caused by a bypass type sampling mode and improve the synchronism of signal detection.
In a first aspect, an embodiment of the present invention provides a mainstream expiratory carbon dioxide concentration and respiratory flow detection apparatus, including:
the fluid passage comprises an inlet section, a detection section and an outlet section, the inlet section is used for being connected with a breathing mask, the outlet section is used for being connected with an exhalation pipeline, the detection section is provided with a first optical detection window and a second optical detection window, and a turbine rotor is arranged in the detection section;
the flow sensing unit is arranged on the first optical detection window;
the carbon dioxide sensing unit is arranged on the second optical detection window;
the processing unit is respectively connected with the flow sensing unit and the carbon dioxide sensing unit;
when expiration gas enters the detection section, the turbine rotor rotates under the action of the expiration gas, and the flow sensing unit generates a corresponding first sub-detection signal and a corresponding second sub-detection signal according to the rotation speed of the turbine rotor; the carbon dioxide sensing unit generates a third sub-detection signal according to the expiration gas; the processing unit determines the flow rate of the expiratory gas according to the first sub-detection signal and the second sub-detection signal, and determines the concentration of carbon dioxide in the expiratory gas according to the third sub-detection signal.
In some optional embodiments, the flow sensing unit includes a first infrared light source emission module, a second infrared light source emission module, a first infrared detector, and a second infrared detector; the first infrared detector is positioned on the optical axis of the first infrared light source emission module, and the detection port of the first infrared detector points to the emission port of the first infrared light source emission module; the second infrared detector is positioned on the optical axis of the second infrared light source emission module, and the detection port of the second infrared detector points to the emission port of the second infrared light source emission module;
when expiration gas enters the detection section, the turbine rotor repeatedly shields infrared light emitted by the first infrared light source emitting module and the second infrared light source emitting module under the action of the expiration gas; the first infrared detector generates a first sub-detection signal according to the shielded light source emitted by the first infrared light source emitting module; the second infrared detector is connected with a second sub-detection signal generated according to the shielded light source emitted by the second infrared light source emitting module; the processing unit determines the flow rate of the expiratory gas according to the first sub-detection signal and the second sub-detection signal.
In some optional embodiments, an inner angle formed by the optical axis of the first infrared light source emission module and the optical axis of the second infrared light source emission module is greater than 0 ° and less than 90 °.
In some optional embodiments, an internal angle formed by the optical axis of the first infrared light source emission module and the optical axis of the second infrared light source emission module is 20 °.
In some optional embodiments, the carbon dioxide sensing unit comprises a third infrared light source emission module and a dual-channel infrared detector, and the third infrared light source emission module and the dual-channel infrared detector are oppositely mounted on the detection section; the dual-channel infrared detector comprises a reference signal channel and a detection channel;
when the expiratory gas enters the detection section, the dual-channel infrared detector generates a third sub-detection signal according to the signal detected by the reference signal channel and the signal detected by the detection channel, and the processing unit determines the concentration of carbon dioxide in the expiratory gas according to the third sub-detection signal.
In some alternative embodiments, the narrowband filter on the reference signal channel has a center wavelength range of [3.9 μm, 4.0 μm ]; the filtered center wavelength on the detection channel comprises 4.26 μm.
In some optional embodiments, the processing unit comprises a processing module, an infrared light detector pre-processing module and an infrared light detector signal processing module; the infrared light detector pre-processing module is used for receiving a first sub-detection signal and a second sub-detection signal sent by the flow sensing unit and shaping the first sub-detection signal, the second sub-detection signal and the second sub-detection signal to obtain a square wave signal; the infrared light detector signal processing module is used for receiving a third sub-detection signal sent by the carbon dioxide sensing unit and processing the third sub-detection signal to obtain a signal to be quantized; the processing module determines the flow of the expiratory gas according to the square wave signal and determines the concentration of carbon dioxide in the expiratory gas according to the signal to be quantified.
In some optional embodiments, the processing unit further includes an infrared light source constant voltage driving module and an infrared light source modulation driving module, and the infrared light source constant voltage driving module is configured to control working states of the first infrared light source emission module and the second infrared light source emission module according to a first control signal of the processing module; and the infrared light source modulation driving module is used for controlling the working state of the third infrared light source emission module according to the second control signal of the processing module.
In some optional embodiments, a first mechanical interface is arranged on the inlet section, and the first mechanical interface is used for connecting a breathing mask; and a second mechanical interface is arranged on the outlet section and is used for connecting an expiration pipeline.
In a second aspect, an embodiment of the present invention provides a method for detecting mainstream expiratory carbon dioxide concentration and respiratory flow, including the following steps:
acquiring a first sub-detection signal and a second sub-detection signal which are obtained by detecting the expiratory gas in the fluid channel by a flow sensing unit, wherein the first sub-detection signal and the second sub-detection signal are both related to the rotating speed of a turbine rotor in the fluid channel;
acquiring a third sub-detection signal obtained by detecting the expiratory gas in the fluid channel by the carbon dioxide sensing unit;
determining the flow rate of the expiratory gas according to the first sub-detection signal and the second sub-detection signal, and determining the concentration of carbon dioxide in the expiratory gas according to the third sub-detection signal.
The device for detecting the concentration and the respiratory flow of the mainstream expiratory carbon dioxide provided by the embodiment of the invention has the following beneficial effects:
this embodiment is achieved by providing a first optical detection window and a second optical detection window on the detection section of the fluid channel, meanwhile, a turbine rotor is arranged in the detection section, the flow sensing unit is arranged at the first optical detection window, the carbon dioxide sensing unit is arranged at the second optical detection window, when the expiratory gas enters the fluid channel, the quantity sensing unit generates a corresponding first sub-detection signal and a second sub-detection signal according to the rotation speed of the turbine rotor, the carbon dioxide sensing unit generates a third sub-detection signal according to the expiratory gas, so that the processing unit can synchronously determine the flow of the expiratory gas according to the first sub-detection signal and the second sub-detection signal, and determine the concentration of carbon dioxide in the expiratory gas according to the third sub-detection signal, therefore, the synchronism of the detection process is improved, and the problems of signal delay and monitoring curve distortion caused by a side-stream sampling mode are avoided.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The invention is further described with reference to the following figures and examples, in which:
FIG. 1 is a schematic structural diagram of a mainstream breath carbon dioxide concentration and breath flow detection device according to an embodiment of the present invention;
FIG. 2 is a block diagram of a processing unit according to an embodiment of the present invention;
FIG. 3 is a schematic view of an installation of a flow sensing unit according to an embodiment of the present invention;
FIG. 4 is a schematic illustration of an installation of a carbon dioxide sensing unit according to an embodiment of the invention;
fig. 5 is a flowchart of a mainstream expiratory carbon dioxide concentration and respiratory flow detection method according to an embodiment of the invention.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, the meaning of a plurality is one or more, the meaning of a plurality is two or more, and the above, below, exceeding, etc. are understood as excluding the present numbers, and the above, below, within, etc. are understood as including the present numbers. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.
In the description of the present invention, reference to the description of the terms "one embodiment," "some embodiments," "an illustrative embodiment," "an example," "a specific example," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Referring to fig. 1, an embodiment of the present invention provides a mainstream expiratory carbon dioxide concentration and respiratory flow detection apparatus, which includes a fluid channel 110, a flow sensing unit 120, a carbon dioxide sensing unit 130, and a processing unit 140. The fluid channel 110 includes an inlet section 111, a detection section 112, and an outlet section 113, wherein the inlet section 111 is used for connecting to a breathing mask, and the outlet section 113 is used for connecting to an exhalation pipeline. The detection section 112 is provided with a first optical detection window (not shown in the figure) for detecting the flow rate of the expiratory gas by the flow sensing unit 120, and a second optical detection window (not shown in the figure) for detecting the concentration of carbon dioxide in the expiratory gas by the carbon dioxide sensing unit 130. A turbine rotor (not shown) is provided in the detection section 112. Both the flow sensing unit 120 and the carbon dioxide sensing unit 130 are connected to a processing unit 140.
Specifically, when expiratory gas enters the detection section (the arrow direction in fig. 1 is the flow direction of the expiratory gas), the turbine rotor rotates under the action of the expiratory gas, so that the detection of the flow sensor on the flow of the expiratory gas is disturbed, and the flow sensing unit generates a corresponding first sub-detection signal and a corresponding second sub-detection signal according to the rotation speed of the turbine rotor, so that the flow of the expiratory gas is detected by the flow sensor. The carbon dioxide sensing unit generates a third sub-detection signal according to the expiration gas. The processing unit synchronously receives the first sub-detection signal, the second sub-detection signal and the third sub-detection signal uploaded by the carbon dioxide sensing unit, determines the flow of the expired gas according to the first sub-detection signal and the second sub-detection signal, and determines the concentration of carbon dioxide in the expired gas according to the third sub-detection signal.
In some embodiments, as shown in fig. 2, the processing unit includes a processing module, an infrared light detector pre-processing module, and an infrared light detector signal processing module. The infrared light detector pre-processing module is used for receiving the first sub-detection signal and the second sub-detection signal sent by the flow sensing unit and shaping the first sub-detection signal and the second sub-detection signal to obtain a square wave signal. The infrared light detector signal processing module is used for receiving a third sub-detection signal sent by the carbon dioxide sensing unit and processing the third sub-detection signal to obtain a signal to be quantized; the processing module determines the flow of the expiratory gas according to the square wave signal and determines the concentration of carbon dioxide in the expiratory gas according to the signal to be quantified. In addition, in order to better control the working states of the flow sensing unit and the carbon dioxide sensing unit, the processing unit further comprises an infrared light source constant voltage driving module and an infrared light source modulation driving module. The infrared light source constant voltage driving module is used for controlling the working states of a first infrared light source emitting module and a second infrared light source emitting module in the flow sensing unit according to a first control signal of the processing module. The infrared light source modulation driving module is used for controlling the working state of a third infrared light source emission module in the carbon dioxide sensing unit according to a second control signal of the processing module.
In some alternative embodiments, the flow sensing unit detects the flow of the expiratory gas using turbine rotor flow detection principles. Specifically, as shown in fig. 3, the flow sensing unit 120 is disposed on the sensing section 112. Specifically, the flow sensing unit 120 includes a first infrared light source emitting module 121, a second infrared light source emitting module 122, a first infrared detector 123 and a second infrared detector 124. The first infrared detector 123 is located on the optical axis of the first infrared light source emitting module 121, and the detection port of the first infrared detector 123 points to the emitting port of the first infrared light source emitting module 121. The second infrared detector 124 is located on the optical axis of the second infrared light source emitting module 122 and the detection port of the second infrared detector 124 points to the emitting port of the second infrared light source emitting module 122. In fig. 3, arrows indicate the light irradiation direction.
In the working process, when expiration gas enters the detection section, the turbine rotor repeatedly shields infrared light emitted by the first infrared light source emitting module and the second infrared light source emitting module under the action of the expiration gas. The first infrared detector is connected with a light source which is emitted by the first infrared light source emitting module after being shielded to generate a first sub-detection signal; the second infrared detector is connected with a light source which is emitted by the second infrared light source emitting module after being shielded to generate a second sub-detection signal; the processing unit determines the flow rate of the expiratory gas according to the first sub-detection signal and the second sub-detection signal. For example, two sub-infrared detectors are taken as the first infrared detector and the second infrared detector, respectively, and two sub-micron infrared light source emission modules are taken as the first infrared light source emission module and the second infrared light source emission module, respectively. With turbine rotor in expiratory gas when expiratory gas is admitted into the sensing sectionThe rotor repeatedly shields the infrared light emitted by the two submicron infrared light source emission modules in the rotating process, and corresponding signals are generated on the two corresponding submicron infrared detectors and are respectively used as a first sub-detection signal and a second sub-detection signal. The first sub-detection signal and the second sub-detection signal exhibit a fluctuating fluctuation under the modulation action of the turbine rotor. The first sub-detection signal and the second sub-detection signal enter the input port of the processing module for processing after passing through the pre-processing module of the infrared light detector in fig. 2. The pre-processing module of the infrared detector in fig. 2 may use a hysteresis comparator to shape the first sub-detection signal and the second sub-detection signal, and after shaping, two square wave signals with identical duty ratios and a certain phase difference may be obtained. By comparing the sequence of the two square wave signals, the rotation direction of the turbine rotor can be judged, so that the flowing direction of the air flow is judged. The frequency of the square wave signal corresponds to the rotational speed of the turbine rotor and is positively correlated with the gas flow rate. In some embodiments, prior to application of the apparatus, the apparatus is calibrated using a standard gas flowmeter to obtain an analytical form of a functional relationship between turbine rotor speed and gas flow, and the functional relationship is fitted using a fifth order polynomial to obtain an array of fitting parameters (α)5，α4，α3，α2，α1，α0). When the rotating speed of the turbine rotor is v, the corresponding expiratory flow phi is alpha5×v5+α4×v4+α3×v3+α2×v2+α1×v+α0。
In some alternative embodiments, in order to enable the two infrared detectors to accurately collect the infrared light emitted by the various infrared light source emitting modules, as shown in fig. 3, an internal angle β formed by the optical axis of the first infrared light source emitting module and the optical axis of the second infrared light source emitting module is set to be greater than 0 ° and less than 90 °. For example, an internal angle β formed by the optical axis of the first infrared light source emission module and the optical axis of the second infrared light source emission module is set to 20 °.
In some alternative embodiments, as shown in FIG. 4The carbon dioxide sensing unit 130 is disposed on the detection section 112. Specifically, the carbon dioxide sensing unit 130 includes a third infrared light source emitting module 131 and a dual-channel infrared detector 132, and the third infrared light source emitting module 131 and the dual-channel infrared detector 132 are oppositely installed on the detection section 112. The dual-channel infrared detector 132 includes a reference signal channel 1321 and a detection channel 1322. In fig. 4, the arrows indicate the light irradiation direction. When the expiratory gas enters the detection section, the dual-channel infrared detector generates a third sub-detection signal according to the signal detected by the reference signal channel and the signal detected by the detection channel, and the processing unit determines the concentration of carbon dioxide in the expiratory gas according to the third sub-detection signal. Specifically, the detection of the carbon dioxide sensing unit is based on the lambert beer law, that is, the amount of absorbed specific infrared light has strong correlation with the concentration of the substance, and the formula I-I can be adoptedmexp (-KCL), wherein I is the light intensity after absorption; i ismIs the light intensity before absorption; k is the absorption coefficient of the characteristic gas, independent of the gas concentration; c is gas concentration; l is the optical path length. In this embodiment, to detect the infrared absorption of carbon dioxide gas, an infrared light source capable of emitting a sensitive infrared spectrum of carbon dioxide gas needs to be selected, and then an infrared detector needs to be used to detect the degree of attenuation of the infrared spectrum of the sensitive spectrum band. In order to achieve the above effect, in the design of the sensing element, the embodiment uses two detectors to detect I respectively0And ItIn which detection I0The channel is defined as a reference signal channel, the center wavelength of the narrow-band filter corresponding to the front end of the detector in the reference signal channel is selected to be between 3.9 mu m and 4.0 mu m, Ref is adopted to represent the reference channel, and the corresponding output signal of the detector is U0. Detection ItThe channel of (2) is defined as a detection channel, the central wavelength of a narrow-band filter at the front end of a detector corresponding to the detection channel is selected to be near 4.26 mu m, preferably 4.26 mu m, the detection channel is represented by Act, and the corresponding detector output signal is Ut. The following relationships exist between the signals: act. U shapet∝It，Ref.：Ut∝ItAccording to lambert beer's law, there are: c ^ f (I)0，It)。
Specifically, when the pyroelectric infrared detector is used as the dual-channel infrared detector, the infrared light source emitted by the third infrared light source emission module needs to work in a modulation state, the modulation frequency is set within the range of 2Hz to 50Hz according to the modulation capability of the infrared detector and the infrared light source, the dual-channel infrared detector detects reference channel light intensity and detection channel light intensity signals of corresponding modulation signal frequency to be used as third sub-detection signals, the third sub-detection signals enter the processing module for digital quantization after passing through the infrared light detector signal processing module in fig. 2, and the quantized digital signals adopt a fast fourier transform algorithm to obtain peak values of the reference channel light intensity and the detection channel light intensity signals at the corresponding modulation frequency. In some embodiments, the carbon dioxide detection unit is calibrated with a standard concentration gas before the device is used, and the functional relationship between the concentration of the carbon dioxide gas and the light intensity signal is obtained. The formula Y is W X (I-exp (-alpha X)β) Non-linear least squares fit to the obtained data. Wherein Y is the absorbance, let Y be 1-Z × It/I0Wherein Z is the carbon dioxide gas concentration of zero ItAnd I0The ratio of (a) to (b). X is the carbon dioxide gas concentration, wherein W, alpha and beta are the parameters to be fitted. After the setting is finished, the concentration of the carbon dioxide in the current expiration gas can be determined according to the infrared signals detected by the dual-channel infrared detector in real time.
In some alternative embodiments, in order to facilitate the connection of the device to other components during the test procedure, a first mechanical interface is provided on the inlet section, the first mechanical interface being used for connecting to a breathing mask. And a second mechanical interface is arranged on the outlet section and is used for connecting an expiration pipeline.
Referring to fig. 5, an embodiment of the present invention provides a method for detecting mainstream expiratory carbon dioxide concentration and respiratory flow, and the embodiment is applied to a processing unit of the apparatus shown in fig. 1.
In the application process, the embodiment includes the following steps:
s51, acquiring a first sub-detection signal and a second sub-detection signal which are obtained by detecting the expiratory gas in the fluid channel through the flow sensing unit, wherein the first sub-detection signal and the second sub-detection signal are related to the rotation speed of the turbine rotor in the fluid channel;
s52, acquiring a third sub-detection signal obtained by detecting the expiratory gas in the fluid channel by the carbon dioxide sensing unit;
and S53, determining the flow rate of the expiratory gas according to the first sub-detection signal and the second sub-detection signal, and determining the concentration of carbon dioxide in the expiratory gas according to the third sub-detection signal.
The content of the embodiment of the device of the invention is applicable to the embodiment of the method, the function of the embodiment of the method is the same as that of the embodiment of the device, and the beneficial effect is the same as that of the device.
The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention. Furthermore, the embodiments of the present invention and the features of the embodiments may be combined with each other without conflict.
Claims (10)
1. A mainstream breath carbon dioxide concentration and breath flow detection device, comprising:
the fluid passage comprises an inlet section, a detection section and an outlet section, the inlet section is used for being connected with a breathing mask, the outlet section is used for being connected with an exhalation pipeline, the detection section is provided with a first optical detection window and a second optical detection window, and a turbine rotor is arranged in the detection section;
the flow sensing unit is arranged on the first optical detection window;
the carbon dioxide sensing unit is arranged on the second optical detection window;
the processing unit is respectively connected with the flow sensing unit and the carbon dioxide sensing unit;
when expiration gas enters the detection section, the turbine rotor rotates under the action of the expiration gas, and the flow sensing unit generates a corresponding first sub-detection signal and a corresponding second sub-detection signal according to the rotation speed of the turbine rotor; the carbon dioxide sensing unit generates a third sub-detection signal according to the expiration gas; the processing unit determines the flow rate of the expiratory gas according to the first sub-detection signal and the second sub-detection signal, and determines the concentration of carbon dioxide in the expiratory gas according to the third sub-detection signal.
2. The device for detecting the mainstream breath carbon dioxide concentration and the breath flow according to claim 1, wherein the flow sensing unit comprises a first infrared light source emitting module, a second infrared light source emitting module, a first infrared detector and a second infrared detector; the first infrared detector is positioned on the optical axis of the first infrared light source emission module, and the detection port of the first infrared detector points to the emission port of the first infrared light source emission module; the second infrared detector is positioned on the optical axis of the second infrared light source emission module, and the detection port of the second infrared detector points to the emission port of the second infrared light source emission module;
when expiration gas enters the detection section, the turbine rotor repeatedly shields infrared light emitted by the first infrared light source emitting module and the second infrared light source emitting module under the action of the expiration gas; the first infrared detector generates a first sub-detection signal according to the shielded light source emitted by the first infrared light source emitting module; the second infrared detector is connected with a second sub-detection signal generated according to the shielded light source emitted by the second infrared light source emitting module; the processing unit determines the flow rate of the expiratory gas according to the first sub-detection signal and the second sub-detection signal.
3. The mainstream breath carbon dioxide concentration and breath flow detection device according to claim 2, wherein an inner angle formed by the optical axis of the first infrared light source emitting module and the optical axis of the second infrared light source emitting module is greater than 0 ° and less than 90 °.
4. The device of claim 3, wherein an interior angle formed by the optical axis of the first infrared light source emitting module and the optical axis of the second infrared light source emitting module is 20 °.
5. The device for detecting the concentration of carbon dioxide and the respiratory flow in mainstream breath according to claim 2, wherein the carbon dioxide sensing unit comprises a third infrared source emission module and a dual-channel infrared detector, and the third infrared source emission module and the dual-channel infrared detector are oppositely mounted on the detection section; the dual-channel infrared detector comprises a reference signal channel and a detection channel;
when the expiratory gas enters the detection section, the dual-channel infrared detector generates a third sub-detection signal according to the signal detected by the reference signal channel and the signal detected by the detection channel, and the processing unit determines the concentration of carbon dioxide in the expiratory gas according to the third sub-detection signal.
6. The mainstream breath carbon dioxide concentration and breath flow detection device according to claim 5, wherein the central wavelength range of the narrow-band filter on the reference signal channel is [3.9 μm, 4.0 μm ]; the filtered center wavelength on the detection channel comprises 4.26 μm.
7. The mainstream breath carbon dioxide concentration and breath flow detection device according to claim 5, wherein said processing unit comprises a processing module, an infrared light detector pre-processing module and an infrared light detector signal processing module; the infrared light detector pre-processing module is used for receiving the first sub-detection signal and the second sub-detection signal sent by the flow sensing unit and shaping the first sub-detection signal and the second sub-detection signal to obtain a square wave signal; the infrared light detector signal processing module is used for receiving a third sub-detection signal sent by the carbon dioxide sensing unit and processing the third sub-detection signal to obtain a signal to be quantized; the processing module determines the flow of the expiratory gas according to the square wave signal and determines the concentration of carbon dioxide in the expiratory gas according to the signal to be quantified.
8. The device for detecting the concentration and the respiratory flow of mainstream expiratory carbon dioxide according to claim 7, wherein the processing unit further comprises an infrared light source constant voltage driving module and an infrared light source modulation driving module, the infrared light source constant voltage driving module is configured to control the working states of the first infrared light source emitting module and the second infrared light source emitting module according to a first control signal of the processing module; and the infrared light source modulation driving module is used for controlling the working state of the third infrared light source emission module according to the second control signal of the processing module.
9. The device of claim 1, wherein a first mechanical interface is disposed on the inlet section, and the first mechanical interface is used to connect to a breathing mask; and a second mechanical interface is arranged on the outlet section and is used for connecting an expiration pipeline.
10. A mainstream method for detecting expiratory carbon dioxide concentration and respiratory flow is characterized by comprising the following steps:
acquiring a first sub-detection signal and a second sub-detection signal which are obtained by detecting the expiratory gas in the fluid channel by a flow sensing unit, wherein the first sub-detection signal and the second sub-detection signal are both related to the rotating speed of a turbine rotor in the fluid channel;
acquiring a third sub-detection signal obtained by detecting the expiratory gas in the fluid channel by the carbon dioxide sensing unit;
determining the flow rate of the expiratory gas according to the first sub-detection signal and the second sub-detection signal, and determining the concentration of carbon dioxide in the expiratory gas according to the third sub-detection signal.
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