A method and system for simultaneous detection of breath methane and hydrogen based on an improved gas sensor

Abstract

The application discloses a breath methane and hydrogen synchronous detection method and system based on an improved gas sensor, and relates to the biomedical detection field.The method comprises the following steps: using the improved gas sensor to synchronously collect a breath flow signal and a sensor original electric signal at a set sampling rate; identifying a breath alveolar air plateau according to the breath flow signal, and intercepting a corresponding sensor original signal segment; performing filter denoising and baseline correction preprocessing on the sensor original signal segment of the plateau; based on the hydrogen and methane response time difference amplified by the gas diffusion delay structure of the improved gas sensor, extracting a first characteristic quantity related to the hydrogen concentration and a second characteristic quantity related to the methane concentration from the preprocessed plateau signal segment; and calculating and outputting the hydrogen concentration value and the methane concentration value according to the first characteristic quantity and the second characteristic quantity.The application can synchronously detect breath methane and hydrogen based on the sensor diffusion delay structure, and has the advantages of low cost, portability and high detection reliability.

Description

Technical Field

[0001] This invention relates to the field of biomedical detection technology, and more specifically to a method and system for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor. Background Technology

[0002] The concentrations of methane and hydrogen in exhaled breath are key biomarkers for assessing gut microbiota function and diagnosing diseases such as small intestinal bacterial overgrowth (SIBO). Clinical practice has shown that simultaneous and correlated analysis of these two gases is of great value and can provide a basis for personalized treatment.

[0003] Currently, the technical solutions for detecting methane and hydrogen in exhaled breath can be mainly divided into the following two categories: The dual-dedicated sensor scheme employs independent methane-selective and hydrogen-selective sensors operating in parallel, outputting the concentrations of the two gases separately. While this scheme can achieve synchronous detection, it suffers from the following drawbacks: (1) High hardware cost: It requires two high-performance sensors and related circuitry, doubling the cost; (2) Complex and bulky system: The dual-gas-path and dual-channel design leads to system complexity, hindering portability; (3) Difficult calibration and maintenance: The two sensors have inconsistent response characteristics, requiring independent calibration, and long-term use may result in drift differences; (4) Cross-interference between sensors: The two sensors may still respond to non-target gases, causing mutual interference.

[0004] The single-sensor plus hardware filtration scheme adds a physical filtration device (such as a palladium-based hydrogen filter layer) to the front end of a single broadband sensor. The filter material selectively removes hydrogen, thereby obtaining a relatively accurate methane reading. However, this scheme has the following problems: (1) sacrifice of hydrogen information: the hydrogen concentration cannot be obtained after filtration, resulting in the loss of important clinical diagnostic information; (2) filter material aging and saturation: the filter material will age and saturate after long-term use, requiring regular replacement and increasing maintenance costs; (3) increased airflow resistance: the filter layer increases airflow resistance, which may affect the stability of breath sampling; (4) response delay: it takes time for gas to pass through the filter layer, resulting in a slower detection response speed.

[0005] In summary, existing technologies cannot simultaneously meet the requirements of low cost, portability, simultaneous detection of two gases, and long-term stability. Therefore, how to provide a monitoring method that maintains the advantages of low cost and small size of a single sensor while simultaneously acquiring accurate methane and hydrogen concentration information, and avoids the drawbacks of hardware filtering, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention provides a method and system for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor, aiming to overcome the shortcomings of the prior art and solve the following core problems: How to achieve high-precision detection of methane and hydrogen simultaneously using only a single low-cost sensor; how to actively amplify the difference in response speed between hydrogen and methane through physical structures, making their signal characteristics easier to distinguish on the time axis; and how to organically combine the innovation of gas diffusion delay structures with signal processing algorithms to form a complete hardware and software collaborative technical solution.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: This invention discloses a method for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor, comprising: S1: Using the improved gas sensor, simultaneously acquire the expiratory flow signal and the sensor's original electrical signal at a set sampling rate; S2: Identify the alveolar plateau phase based on the expiratory flow signal and extract the corresponding original sensor signal segment; S3: Perform filtering, noise reduction, and baseline correction preprocessing on the raw sensor signal segment during the plateau period; S4: Based on the amplified hydrogen and methane response time difference caused by the gas diffusion delay structure of the improved gas sensor, extract the first feature quantity related to hydrogen concentration and the second feature quantity related to methane concentration from the preprocessed plateau period signal segment, respectively. S5: Calculate and output the hydrogen concentration value and the methane concentration value based on the first characteristic value and the second characteristic value.

[0008] Furthermore, the set sampling rate is not less than 20Hz; The expiratory alveolar plateau phase is the period in the mid-to-late expiratory phase where the flow rate is stable and lasts for more than 3 seconds.

[0009] Furthermore, in S4, the time-domain peak separation method, the feature time window integration method, or the improved double exponential model fitting method are used to extract features.

[0010] Furthermore, the time-domain peak separation method specifically includes: In the plateau signal segment, identify the first response peak and record the peak amplitude. As the first feature quantity; identify the plateau region where the signal tends to stabilize and record the stable value. This serves as the second characteristic quantity.

[0011] Furthermore, the feature time window integration method is specifically as follows: Based on the pre-calibrated hydrogen delay time and methane delay time The plateau signal segment is divided into an early time window and a late time window; the integral value of the signal within the early time window and the late time window is calculated respectively. and , respectively serving as the first feature quantity and the second feature quantity.

[0012] Furthermore, the improved double-exponential model fitting method is specifically as follows: Establish a double-exponential dynamic model that considers diffusion delay: ; in, For sensors Theoretical output voltage at any moment It is a unit step function. and The pre-calibrated hydrogen delay time and methane delay time are... and The inherent response time constant of the sensor, and For the concentration-related amplitude parameter to be determined, This is the baseline constant; The model is fitted using a nonlinear least squares algorithm to obtain the solution. and These are respectively used as the first feature quantity and the second feature quantity.

[0013] Furthermore, the improved gas sensor includes: a substrate, a gas-sensitive layer, and a gas path channel; The gas-sensitive layer is disposed on the substrate; the gas-sensitive layer is responsive to both methane and hydrogen. The gas passage is located upstream of the gas-sensitive layer; a gas diffusion delay structure is provided in the gas passage, and the gas diffusion delay structure is configured such that the time difference between hydrogen and methane gas reaching the gas-sensitive layer is greater than a preset threshold.

[0014] Furthermore, the gas diffusion delay structure includes a tortuous gas diffusion channel and a plurality of staggered baffles or columnar arrays disposed within the gas diffusion channel.

[0015] Furthermore, the gas diffusion channel is a serpentine or spiral tortuous channel with a hydraulic diameter of 10-100 μm; the ratio of the channel length L to the cross-sectional area S, L / S, is ≥ 200 cm². -1 The spacing between the baffles or columnar arrays is ≤50μm.

[0016] This invention also discloses a system for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor, comprising: The improved gas sensor; The flow detection module is used to monitor expiratory flow in real time; The signal acquisition module is used to acquire the output signals of the sensors; The processing control module includes a memory and a processor. The memory stores a computer program, and the processor executes the program to implement the steps of any of the above-described detection methods. The output module displays and outputs methane concentration, hydrogen concentration, and derivatization analysis results. The power supply module provides power to each module.

[0017] As can be seen from the above technical solution, compared with the prior art, the present invention provides a method and system for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor, which has the following beneficial effects: (1) Actively amplify gas response differences: By optimizing the gas diffusion delay structure, the time difference between hydrogen and methane reaching the sensitive layer can be amplified from several seconds to more than 20-30 seconds, and the signal characteristics are significantly separated on the time axis, creating excellent conditions for subsequent algorithm processing.

[0018] (2) Simplified algorithm and low computational resource requirements: Based on the difference of the amplified signal, gas separation can be achieved by simple peak detection or time window integration method without complex fitting, which reduces the requirements for microcontroller performance and is conducive to realizing ultra-low power consumption applications.

[0019] (3) Dual gas synchronous detection: Simultaneous acquisition of methane and hydrogen concentration information on a single sensor platform, which makes up for the deficiency of hydrogen information loss in hardware filtration schemes and provides more comprehensive data support for clinical diagnosis.

[0020] (4) Significantly improved detection robustness: The initial separation provided by the physical structure reduces the sensitivity of the final detection results to factors such as sensor batch differences, environmental fluctuations, and changes in expiratory flow rate, resulting in excellent overall detection robustness.

[0021] (5) Low cost and small size: The design of a single sensor plus microstructure has a hardware cost that is much lower than that of a dual sensor solution. It is small in size and low in power consumption, making it easy to integrate into portable devices.

[0022] (6) Hardware and software synergy, comprehensive patent protection: This invention forms a complete technical solution of "hardware structure innovation + software algorithm innovation", and builds a double patent barrier that is difficult to bypass.

[0023] (7) Rich information output: Simultaneously outputs methane concentration, hydrogen concentration and CH4 / H2 ratio, providing multidimensional data support for clinical diagnosis and intestinal health assessment. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of the method flow provided by the present invention.

[0026] Figure 2 This is a schematic diagram of the sensor structure of the present invention.

[0027] Figure 3 This is a magnified view of a localized gas diffusion delay structure.

[0028] Figure 4 The system structure block diagram provided by the present invention.

[0029] In the diagram, 1 is the substrate; 2 is the gas-sensitive layer; 3 is the silicon cap; 4 is the channel; 5 is the baffle array; 6 is the gas inlet; 7 is the gas outlet; 8 is the shell; and 9 is the pin. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] This invention discloses a method for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor, such as... Figure 1 As shown, it includes: S1: Using an improved gas sensor, the expiratory flow signal and the sensor's raw electrical signal are simultaneously acquired at a set sampling rate; S2: Identify the alveolar plateau phase based on the expiratory flow signal and extract the corresponding original sensor signal segment; S3: Perform filtering, noise reduction, and baseline correction preprocessing on the raw sensor signal segment during the plateau period; S4: Based on the amplified hydrogen and methane response time difference amplified by the gas diffusion delay structure of the improved gas sensor, the first feature quantity related to hydrogen concentration and the second feature quantity related to methane concentration are extracted from the preprocessed plateau period signal segment, respectively. S5: Calculate and output the hydrogen concentration value and the methane concentration value based on the first characteristic value and the second characteristic value.

[0032] In one specific embodiment, the sampling rate is set to be no less than 20Hz; the expiratory alveolar plateau phase is the period in which the flow rate is stable and lasts for more than 3 seconds during the mid-to-late expiratory phase.

[0033] In a specific embodiment, feature extraction is performed in S4 using the time-domain peak separation method, the feature time window integration method, or the improved double exponential model fitting method.

[0034] In a specific embodiment, the time-domain peak separation method is as follows: During the plateau signal segment, identify the first response peak and record the peak amplitude. As the first feature quantity; it identifies plateau regions where the signal tends to stabilize and records stable values. As the second characteristic quantity; Calculate the hydrogen concentration based on the pre-calibrated peak-concentration relationship. and methane concentration ,in and These are the peak-concentration relationship functions for hydrogen and methane, respectively, obtained through prior calibration using standard hydrogen and standard methane gases of different concentrations. The peak-concentration relationship can be a linear function, a polynomial function, or a lookup table.

[0035] In a specific embodiment, the feature time window integration method is as follows: Based on the pre-calibrated hydrogen delay time and methane delay time The plateau signal segment is divided into an early time window and a late time window; the integral values ​​of the signal within the early time window and the late time window are calculated respectively. and , respectively serving as the first and second feature quantities; Calculate the hydrogen and methane concentrations based on the pre-calibrated integral-concentration relationship.

[0036] In one specific embodiment, the improved double-exponential model fitting method is as follows: Establish a double-exponential dynamic model that considers diffusion delay: ; in, For sensors Theoretical output voltage at any moment It is a unit step function. and The pre-calibrated hydrogen delay time and methane delay time are... and The inherent response time constant of the sensor, and For the concentration-related amplitude parameter to be determined, This is the baseline constant; The model is fitted using a nonlinear least squares algorithm to solve for... and These are respectively used as the first and second feature quantities; Calculate the hydrogen and methane concentrations based on the pre-calibrated amplitude-concentration relationship.

[0037] In one specific embodiment, the improved gas sensor includes: a substrate, a gas-sensitive layer, and a gas passage; The gas-sensitive layer is disposed on the substrate; the gas-sensitive layer responds to both methane and hydrogen. The gas passage is located upstream of the gas-sensitive layer; a gas diffusion delay structure is provided in the gas passage, and the gas diffusion delay structure is configured such that the time difference between hydrogen and methane reaching the gas-sensitive layer is greater than a preset threshold.

[0038] The improved gas sensor operates as follows: A breath sample enters through the gas inlet and flows through a gas diffusion delay structure. Due to its small molecular weight and high diffusion coefficient, hydrogen experiences fewer collisions and a shorter effective path within the delay structure, allowing it to quickly reach the gas-sensitive layer. Conversely, methane, with its large molecular weight and low diffusion coefficient, experiences more collisions and a longer effective path within the delay structure, significantly delaying its arrival at the sensitive layer. Consequently, the responses of the two gases are significantly separated along the time axis.

[0039] In one specific embodiment, the gas diffusion delay structure includes a tortuous gas diffusion channel and a plurality of staggered baffles or columnar arrays disposed within the gas diffusion channel.

[0040] In one specific embodiment, the gas diffusion channel is a serpentine or spiral tortuous channel with a hydraulic diameter of 10-100 μm; the ratio of the channel length L to the cross-sectional area S, L / S ≥ 200 cm². -1 The spacing between baffles or columnar arrays is ≤50μm.

[0041] This invention also discloses a system for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor, such as... Figure 4 As shown, it includes: Improve gas sensors; The flow detection module is used to monitor expiratory flow in real time; The signal acquisition module is used to acquire the output signals of the sensors; The processing control module includes a memory and a processor. The memory stores a computer program, and the processor executes the program to implement the steps of any of the above detection methods. The output module displays and outputs methane concentration, hydrogen concentration, and derivatization analysis results. The power supply module provides power to each module.

[0042] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0043] Example 1: Sensor with serpentine diffusion delay structure and peak separation method

[0044] 1. Sensor structure design and fabrication

[0045] Reference Figure 2 The sensor in this embodiment includes a silicon-based microthermal plate substrate 1, measuring 2mm × 2mm, which integrates a platinum heating resistor and a temperature sensor. A SnO2 nanofilm, approximately 500nm thick, is deposited on the substrate by magnetron sputtering as a gas-sensitive layer 2, and annealed to form a porous structure to enhance gas sensitivity.

[0046] A micro-machined silicon cap 3 is bonded above the sensitive layer using an anodic bonding process. Inside the cap, a serpentine channel 4 is fabricated using deep reactive ion etching. The sensor is packaged in a standard TO-39 housing 8. The gas inlet 6 and gas outlet 7 are located on opposite sides of the housing, forming a through-flow gas flow. Pins 9 are mounted at the bottom.

[0047] Figure 3 A magnified view of a portion of the serpentine channel is shown. The serpentine channel is 50 μm wide, 20 μm deep, and 8 cm long. An array of five staggered cylindrical baffles, each 10 μm in diameter and spaced 20 μm apart, is etched within the channel. The channel length L = 8 cm, and the cross-sectional area S = 50 μm × 20 μm = 1000 μm². 2 L / S = 80cm / 0.001cm 2 =80,000cm -1 Much larger than 200cm -1 Design requirements: baffle spacing d = 20μm ≤ 50μm.

[0048] 2. Calibration process

[0049] Delay time calibration: Pure hydrogen (50 ppm) and pure methane (50 ppm) standard gases were introduced into the sensor respectively, and the time from the gas inlet to the generation of a response in the sensitive layer was recorded. The measured... =2.3 seconds, =25.8 seconds, time difference 23.5 seconds.

[0050] Concentration calibration: Prepare a series of standard gases of different concentrations of pure hydrogen (0, 10, 30, 50, 80, 100 ppm) and pure methane (0, 5, 10, 20, 30, 50 ppm), and record their response peak height (hydrogen) and plateau stability value (methane) respectively to establish a calibration curve: (Unit: ppm) (Unit: mV) (Unit: ppm) (Unit: mV) 3. Testing Process Following the on-screen instructions, the user takes a deep breath, holds it for 10 seconds, and then exhale steadily for 15 seconds through the mouthpiece. The system simultaneously acquires the flow rate signal F(t) and the sensor voltage signal V(t) at a sampling rate of 50Hz.

[0051] When the flow rate stabilizes at 100-300 mL / s for more than 3 seconds, the alveolar plateau phase is determined, and the plateau phase signal V_platform(t) is captured for 8 seconds. A moving average filter (0.2-second window) is applied to V_platform(t) to remove high-frequency noise.

[0052] Peak separation was used to process the signal: local maxima were searched within the plateau period. The first peak was detected at t=2.5 seconds. =20.1mV. The signal then continued to rise slowly, stabilizing after t=15.8 seconds. The average value of the last 2 seconds was taken as P. =8.3mV.

[0053] Concentration calculation: ; .

[0054] Example 2: Using a spiral diffusion delay structure and time window integration method

[0055] 1. Sensor structural differences: This embodiment uses a spiral diffusion delay structure instead of a serpentine cavity, with a total channel length of 10cm. Other parameters are the same as in Embodiment 1. The spiral design allows for a longer diffusion path within the same package area.

[0056] 2. Calibration process

[0057] Measured =2.1 seconds, =28.3 seconds, time difference 26.2 seconds.

[0058] Prepare mixed gases of different concentrations (CH4: 5-30ppm, H2: 10-80ppm), calculate the signal integral values ​​for the early time window [1s, 4s] and the late time window [15s, 20s] respectively, and establish a calibration matrix: ; Right now: =0.12× +0.03× ; =0.02× +0.15× ; 3. Testing Process Signal acquisition and plateau period identification are the same as in Example 1. Based on the calibrated delay time, the early window is set to 1-4 seconds after the start of the plateau period, and the late window is set to 15-20 seconds. The integral values ​​of the signal within each time window are calculated: =45.2mV·s, =28.6 mV·s. Solve the concentration equations based on the calibration matrix: 45.2 = 0.12 × +0.03× ; 28.6 = 0.02 × +0.15× ; Solving for: =50.3ppm, =15.0ppm. Derivative analysis and output are the same as in Example 1.

[0059] Example 3: High-precision detection using a double exponential model fitting

[0060] 1. The sensor structure is the same as in Example 1.

[0061] 2. Calibration process

[0062] Delay time calibration: =2.3 seconds, =25.8 seconds.

[0063] Response time constant calibration: Apply step concentrations of pure hydrogen and pure methane to the sensor respectively, and obtain the result by fitting. =5.2 seconds, =12.8 seconds.

[0064] Amplitude-concentration calibration: Establishment and , and The linear relationship, and the calibration curves are respectively =10.2× , =8.5× .

[0065] 3. Testing Process

[0066] Signal acquisition and plateau identification are the same as in Example 1. An improved double-exponential model is established: ; The Levenberg-Marquardt algorithm is used to fit the plateau signal and solve iteratively. , And C. The goodness of fit R² = 0.992. The concentration was calculated based on the calibration curve: =10.2× =10.2 × 4.92 = 50.2 ppm =8.5× =8.5 × 1.78 = 15.1 ppm The output results are the same as in Example 1.

[0067] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0068] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor, characterized in that, include: S1: Using the improved gas sensor, simultaneously acquire the expiratory flow signal and the sensor's original electrical signal at a set sampling rate; S2: Identify the alveolar plateau phase based on the expiratory flow signal and extract the corresponding original sensor signal segment; S3: Perform filtering, noise reduction, and baseline correction preprocessing on the raw sensor signal segment during the plateau period; S4: Based on the amplified hydrogen and methane response time difference caused by the gas diffusion delay structure of the improved gas sensor, extract the first feature quantity related to hydrogen concentration and the second feature quantity related to methane concentration from the preprocessed plateau period signal segment, respectively. S5: Calculate and output the hydrogen concentration value and the methane concentration value based on the first characteristic value and the second characteristic value.

2. The method for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor according to claim 1, characterized in that, The set sampling rate is not less than 20Hz; The expiratory alveolar plateau phase is the period in the mid-to-late expiratory phase where the flow rate is stable and lasts for more than 3 seconds.

3. The method for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor according to claim 1, characterized in that, In S4, the time-domain peak separation method, the feature time window integration method, or the improved double exponential model fitting method are used to extract features.

4. The method for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor according to claim 3, characterized in that, The time-domain peak separation method is specifically as follows: In the plateau signal segment, identify the first response peak and record the peak amplitude. As the first feature quantity; Identify the plateau region where the signal tends to stabilize and record the stable values. This serves as the second characteristic quantity.

5. The method for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor according to claim 3, characterized in that, The feature time window integration method is specifically as follows: Based on the pre-calibrated hydrogen delay time and methane delay time The plateau signal segment is divided into an early time window and a late time window; the integral value of the signal within the early time window and the late time window is calculated respectively. and , respectively serving as the first feature quantity and the second feature quantity.

6. The method for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor according to claim 3, characterized in that, The improved double-exponential model fitting method is specifically as follows: Establish a double-exponential dynamic model that considers diffusion delay: ； in, For sensors Theoretical output voltage at any moment It is a unit step function. and The pre-calibrated hydrogen delay time and methane delay time are... and This is the inherent response time constant of the sensor. and For the concentration-related amplitude parameter to be determined, This is the baseline constant; The model is fitted using a nonlinear least squares algorithm to obtain the solution. and These are respectively used as the first feature quantity and the second feature quantity.

7. The method for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor according to claim 1, characterized in that, The improved gas sensor includes: a substrate, a gas-sensitive layer, and a gas passage. The gas-sensitive layer is disposed on the substrate; the gas-sensitive layer is responsive to both methane and hydrogen. The gas passage is located upstream of the gas-sensitive layer; a gas diffusion delay structure is provided in the gas passage, and the gas diffusion delay structure is configured such that the time difference between hydrogen and methane gas reaching the gas-sensitive layer is greater than a preset threshold.

8. A method for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor according to claim 7, characterized in that, The gas diffusion delay structure includes a tortuous gas diffusion channel and a plurality of staggered baffles or columnar arrays disposed within the gas diffusion channel.

9. A method for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor according to claim 8, characterized in that, The gas diffusion channel is a serpentine or spiral-shaped tortuous channel with a hydraulic diameter of 10-100 μm; the ratio of the channel length L to the cross-sectional area S, L / S ≥ 200 cm². -1 The spacing between the baffles or columnar arrays is ≤50μm.

10. A system for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor, employing the method for simultaneous detection of exhaled methane and hydrogen based on an improved gas sensor as described in any one of claims 1 to 9, characterized in that, include: The improved gas sensor; The flow detection module is used to monitor expiratory flow in real time; The signal acquisition module is used to acquire the output signals of the sensors; The processing control module includes a memory and a processor. The memory stores a computer program, and the processor executes the program to implement the steps of any of the above-described detection methods. The output module displays and outputs methane concentration, hydrogen concentration, and derivatization analysis results. The power supply module provides power to each module.

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