A membrane face humidity buffer, droplet interception and protection reset structure and method for an exhaled breath electrochemical sensor

Abstract

The application relates to the technical field of exhaled air electrochemical detection, and discloses a film surface humidity buffering, liquid drop intercepting and protection resetting structure and method for an exhaled air electrochemical sensor. The structure comprises an exhalation inlet, an exhalation flow guide unit, a humidity buffering unit, a liquid drop intercepting unit, an electrochemical sensor detection unit, a signal acquisition unit, a control unit, a protection resetting unit, a dry gas bypass unit, a heating resetting unit, a display output unit and a storage unit. The humidity buffering unit reduces the impact of high-humidity exhaled air on the sensor film surface, the liquid drop intercepting unit guides away condensed liquid through a film surface protection cavity, a capillary liquid guide groove and a condensed liquid temporary storage area; when the humidity state, the liquid drop state or the baseline drift state exceeds a protection threshold value, the control unit intercepts the detection result, executes bypass moisture removal, dry gas resetting and / or heating resetting, and re-allow detection after meeting the access conditions. The application is used for improving detection repeatability and reliability.

Description

Technical Field

[0001] This invention relates to the field of exhaled breath electrochemical detection technology, and in particular to a membrane surface humidity buffer, droplet interception and protection reset structure and method for exhaled breath electrochemical sensors. Background Technology

[0002] Gases such as nitric oxide, carbon monoxide, hydrogen sulfide, ammonia, and hydrogen in exhaled breath can be detected by electrochemical sensors. Electrochemical sensors typically rely on the electrochemical reaction that occurs at the electrode detection interface after the target gas passes through the sensor's diffusion membrane. Therefore, their detection repeatability is closely related to the humidity state, droplet state, and gas diffusion state at the front end of the sensor's diffusion membrane.

[0003] The breath exhaled by subjects is typically highly humid. When this humid exhaled breath enters a cooler gas path or the sensor front end, it is prone to condensation in the sensor diffusion membrane, membrane protection area, or connecting channels. Once condensate droplets adhere to the vicinity of the sensor diffusion membrane, they alter the diffusion path and rate of the target gas, causing slow response, baseline drift, and insufficient recovery. In severe cases, this can even affect the lifespan of the electrochemical sensor.

[0004] Existing devices typically employ simple filtration, ordinary dehumidification, or software compensation methods that cannot establish a clear membrane-level humidity buffer and droplet-guiding structure at the sensor's diffusion membrane front end. They also lack closed-loop control mechanisms such as bypass dehumidification, dry gas reset, heating reset, and baseline restoration access after membrane surface anomalies occur. If the device continues to output detection results despite abnormal membrane surface humidity or unremoved droplets, the reliability of exhaled gas electrochemical detection is easily reduced. Summary of the Invention

[0005] The technical problem to be solved by this invention is that during the electrochemical detection of exhaled breath, high humidity sample gas or condensed droplets can easily act on the front end of the diffusion membrane of the electrochemical sensor, resulting in changes in the diffusion path, baseline drift, insufficient recovery, and reduced detection repeatability.

[0006] To address the aforementioned technical problems, this invention provides a membrane humidity buffering, droplet interception, and protection reset structure for an exhaled gas electrochemical sensor. The structure includes an exhalation inlet, an exhalation flow guiding unit, a humidity buffering unit, a droplet interception unit, an electrochemical sensor detection unit, a signal acquisition unit, a control unit, a protection reset unit, a dry gas bypass unit, a heating reset unit, a display output unit, and a storage unit. The exhalation inlet is connected to the electrochemical sensor detection unit via the exhalation flow guiding unit, the humidity buffering unit, and the droplet interception unit. The signal acquisition unit acquires the response signal from the electrochemical sensor detection unit. The control unit controls the protection reset unit, the dry gas bypass unit, and the heating reset unit based on the humidity state, droplet state, or baseline drift state, and intercepts the target gas detection result during the protection reset period.

[0007] In a preferred embodiment, the humidity buffer unit includes a humidity buffer chamber and a hydrophobic microporous membrane; the droplet interception unit includes a membrane surface protection chamber, a capillary liquid guiding groove, and a condensate storage area; and the electrochemical sensor detection unit includes a sensor diffusion membrane, a sensor housing, a working electrode, a reference electrode, and a counter electrode. When a membrane surface abnormality occurs, the control unit shuts off or restricts the entry of sample gas and restores the baseline to a preset range through bypass dehumidification, dry gas reset, and / or heating reset. Detection is allowed again once the baseline state, humidity state, and droplet state meet the detection access conditions.

[0008] The present invention also provides a method for resetting the membrane protection of an exhaled gas electrochemical sensor, comprising waiting for exhalation and collecting humidity and droplet state, determining whether a protection threshold is exceeded based on the humidity state, droplet state or baseline drift state; if the protection threshold is not exceeded, allowing sample gas to enter the sensor and outputting detection results; if the protection threshold is exceeded, closing the sample injection and opening the bypass dehumidification, then opening dry gas reset and / or heating reset, and allowing detection again after the baseline is restored.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: First, the present invention extends ordinary gas path dehumidification to membrane-level humidity buffering and droplet interception at the front end of the sensor diffusion membrane, reducing the direct impact of high-humidity exhaled gas on the sensor diffusion membrane; Second, the present invention guides condensate away from the sensor diffusion membrane through capillary liquid guiding grooves and condensate temporary storage areas, preventing droplets from changing the diffusion path; Third, the present invention forms a closed loop through bypass dehumidification, dry gas reset and / or heating reset, and baseline recovery access control, so that the target gas detection result is not output when the membrane surface condition does not meet the conditions, thereby improving the reliability of exhaled gas electrochemical detection. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of the system structure; Figure 2 This is a schematic diagram of the connection structure; Figure 3 This is a schematic diagram showing the relationship between gas path switching and protection reset control. Figure 4 This is a schematic diagram of the membrane surface anomaly detection and protection reset process; Figure 5 This is a schematic diagram illustrating the relationship between baseline drift and time. Detailed Implementation

[0011] The present invention will be described below with reference to embodiments. The described embodiments are used to explain the technical solutions of the present invention and do not limit the scope of protection of the present invention.

[0012] Example 1: As Figure 1As shown, the membrane surface humidity buffer, droplet interception, and protection reset structure includes an exhalation inlet 1, an exhalation flow guiding unit 2, a humidity buffer unit 3, a droplet interception unit 4, an electrochemical sensor detection unit 5, a signal acquisition unit 6, a control unit 7, a protection reset unit 8, a dry gas bypass unit 9, a heating reset unit 10, a display output unit 11, and a storage unit 12. The exhalation inlet 1 receives the sample gas exhaled by the subject, and the exhalation flow guiding unit 2 guides the exhaled gas sample into the humidity buffer unit 3. The humidity buffer unit 3 reduces the direct impact of high-humidity exhaled gas on the downstream membrane surface structure. The droplet interception unit 4 intercepts or guides condensed droplets, the electrochemical sensor detection unit 5 generates an electrochemical response to the target gas, and the signal acquisition unit 6 acquires the electrochemical response signal.

[0013] like Figure 1 As shown, the control unit 7 is connected to the signal acquisition unit 6, the protection reset unit 8, the dry gas bypass unit 9, the heating reset unit 10, the display output unit 11, and the storage unit 12. Based on the humidity status, droplet status, and the baseline status of the electrochemical sensor detection unit 5, the control unit 7 controls the protection reset unit 8, the dry gas bypass unit 9, and the heating reset unit 10 to perform protection resets. During the protection reset, a reset prompt or abnormality prompt is output through the display output unit 11. After the reset conditions are met, the control unit 7 allows detection again and outputs the detection results through the display output unit 11 after subsequent effective detection is completed. The storage unit 12 is used to save detection data, reset status, and baseline recovery records.

[0014] Example 2: Figure 2 As shown, the sample gas inlet 21 is connected to the humidity buffer chamber 22, and a hydrophobic microporous membrane 23 is disposed between the humidity buffer chamber 22 and the membrane protection chamber 24. The hydrophobic microporous membrane 23 is used to block droplets or large particles of condensate from entering the membrane protection chamber 24, while allowing the target gas components to pass through. The membrane protection chamber 24 is disposed between the hydrophobic microporous membrane 23 and the sensor diffusion membrane 25, and is used to form a buffer gap at the front end of the sensor diffusion membrane 25. The sensor diffusion membrane 25 is disposed between the membrane protection chamber 24 and the sensor housing 26. The sensor housing 26 is provided with a working electrode 27, a reference electrode 28, and a counter electrode 29. After the exhaled gas sample enters through the sensor diffusion membrane 25, it reacts with the electrochemical sensor, and the reacted gas is discharged through the exhaust outlet 32.

[0015] like Figure 2 As shown, the capillary guide channel 30 is located in the lower region of the membrane protection cavity 24 and communicates with the condensate storage area 31. When condensate droplets appear in the membrane protection cavity 24, the condensate enters the capillary guide channel 30 under capillary action and gravity, and is guided to the condensate storage area 31, thereby reducing the possibility of condensate directly covering the sensor diffusion membrane 25. In this embodiment, Figure 2The humidity buffer chamber 22 in the middle can be used as Figure 1 The specific cavity of the medium humidity buffer unit 3, the membrane protection cavity 24 and the capillary liquid guiding groove 30 can be used as Figure 1 The specific structure of the droplet interception unit 4 includes the sensor diffusion film 25, sensor housing 26, working electrode 27, reference electrode 28, and counter electrode 29, which can serve as... Figure 1 The specific structure of the electrochemical sensor detection unit 5.

[0016] Example 3: Figure 3 As shown, the gas path switching and protection reset control relationship includes an exhalation inlet 41, a sample injection valve 42, a humidity buffer chamber 43, a bypass valve 44, a dry gas inlet 45, a heating reset unit 46, a sensor reaction chamber 47, an exhaust valve 48, and a control unit 49. In the detection state, the exhaled gas sample sequentially enters the sensor reaction chamber 47 through the exhalation inlet 41, the sample injection valve 42, the humidity buffer chamber 43, and the bypass valve 44, and is discharged through the exhaust valve 48. In the protection reset state, the control unit 49 controls the sample injection valve 42, the bypass valve 44, the heating reset unit 46, and the exhaust valve 48, causing the reset gas flow from the dry gas inlet 45 to enter the inlet side of the bypass valve 44 via the reset branch, then enter the sensor reaction chamber 47, and is discharged through the exhaust valve 48. The heating reset unit 46 is used to heat and reset the reset branch, the front end area of ​​the sensor reaction chamber 47, or the relevant membrane area, thereby achieving membrane dehumidification and baseline restoration.

[0017] In this embodiment, Figure 3 The humidity buffer chamber 43 in the middle can correspond to Figure 1 The humidity buffer unit 3, bypass valve 44, dry air inlet 45 and its reset branch can be used as Figure 1 The specific structure of the intermediate dry gas bypass unit 9 can be corresponding to the heating reset unit 46. Figure 1 The heating reset unit 10 and the sensor reaction chamber 47 can be used as... Figure 1 The reaction chamber structure of the electrochemical sensor detection unit 5 and the control unit 49 can correspond to it. Figure 1 Control unit 7 in the middle.

[0018] Example 4: Figure 4 As shown, the membrane surface anomaly judgment and protection reset process includes waiting for exhalation 401, collecting humidity and droplet state data 402, and determining whether the protection threshold has been exceeded 403. If the judgment result is negative, sample gas is allowed to enter the sensor 408, and the detection result is output 409. If the judgment result is positive, the sample injection is closed and the bypass dehumidification is opened 404, followed by dry gas and / or heating reset 405, and then the baseline is judged to have recovered 406; if the baseline has not recovered, the dry gas and / or heating reset 405 is continued; if the baseline has recovered, the detection is allowed again 407.

[0019] Example 5: Figure 5 As shown, the vertical axis 501 represents the baseline drift, and the horizontal axis 502 represents time. Figure 5 The diagram sequentially illustrates the exhalation impact phase 503, humidity buffering phase 504, droplet interception phase 505, protection reset phase 506, and baseline recovery phase 507. A first drift curve 508 and a second drift curve 509 are used to represent the baseline drift trend under different membrane state control conditions. In one example, the first drift curve 508 can be used to represent the baseline drift change when membrane protection reset is not performed in a timely manner or is insufficient, while the second drift curve 509 can be used to represent the baseline drift change after employing a closed loop of humidity buffering, droplet interception, and protection reset.

[0020] In one specific application, the target gas can be any exhaled gas component that can be detected by an electrochemical sensor, such as nitric oxide, carbon monoxide, hydrogen sulfide, ammonia, or hydrogen. For different target gases, different protection thresholds, reset heating power, bypass dehumidification time, and dry gas reset time can be set according to the type of electrochemical sensor, the area of ​​the sensor diffusion membrane, the volume of the membrane protection chamber, the volume of the humidity buffer chamber, and the response recovery time. This invention forms a closed loop through humidity buffering, droplet interception, capillary liquid guidance, protection reset, and baseline access control, ensuring that abnormal membrane conditions do not directly translate into detection result errors.

Claims

1. A membrane surface humidity buffer, droplet interception, and protection reset structure for an exhaled gas electrochemical sensor, comprising an exhaled air inlet, an exhaled air guiding unit, a humidity buffer unit, a droplet interception unit, an electrochemical sensor detection unit, a signal acquisition unit, a control unit, a protection reset unit, a dry gas bypass unit, a heating reset unit, a display output unit, and a storage unit, characterized in that, The exhalation inlet is connected to the humidity buffer unit via the exhalation guiding unit. The humidity buffer unit is used to create a humidity buffer state for the exhaled gas sample before it enters the front end of the sensor diffusion membrane of the electrochemical sensor detection unit. The droplet interception unit is disposed between the humidity buffer unit and the electrochemical sensor detection unit to intercept or guide condensed droplets. The signal acquisition unit is connected to the electrochemical sensor detection unit. The control unit is connected to the signal acquisition unit, the protection reset unit, the dry gas bypass unit, the heating reset unit, the display output unit, and the storage unit. When the control unit determines that there is an abnormal membrane humidity, an abnormal droplet interception, or an abnormal baseline recovery, it controls the protection reset unit, the dry gas bypass unit, or the heating reset unit to perform a protection reset, and prohibits the output of the target gas detection result during the protection reset. After the reset conditions are met, the signal acquisition unit is allowed to acquire the electrochemical response signal.

2. The structure according to claim 1, characterized in that, The humidity buffer unit includes a humidity buffer chamber and a hydrophobic microporous membrane. The humidity buffer chamber is located upstream of the hydrophobic microporous membrane. The hydrophobic microporous membrane is used to block droplets from entering the membrane surface protection area and allow the target gas components to pass through.

3. The structure according to claim 1, characterized in that, The droplet interception unit includes a membrane protection cavity, a capillary liquid guiding groove, and a condensate storage area. The membrane protection cavity is located between the downstream side of the humidity buffer unit and the front end of the sensor diffusion membrane of the electrochemical sensor detection unit. The capillary liquid guiding groove is located in the lower region of the membrane protection cavity and communicates with the condensate storage area, and is used to guide the condensate formed in the membrane protection cavity away from the region in front of the sensor diffusion membrane.

4. The structure according to claim 1, characterized in that, The electrochemical sensor detection unit includes a sensor diffusion membrane, a sensor housing, a working electrode, a reference electrode, and a counter electrode. The sensor diffusion membrane is disposed between the droplet interception unit and the sensor housing, and the working electrode, reference electrode, and counter electrode are disposed inside the sensor housing.

5. The structure according to claim 1, characterized in that, The dry gas bypass unit includes a dry gas inlet, a bypass valve, and a reset branch. The reset branch is connected to the inlet side of the bypass valve or to the front end of the sensor reaction chamber of the electrochemical sensor detection unit connected to the bypass valve, and is used to provide dry gas reset flow to the sensor reaction chamber or membrane protection area in the protection reset state.

6. The structure according to claim 1, characterized in that, The heating reset unit is located near the dry gas reset branch, in the membrane protection area of ​​the droplet interception unit, in the sensor reaction chamber of the electrochemical sensor detection unit, or in the front end area of ​​the electrochemical sensor detection unit. The control unit drives the heating reset unit in an intermittent heating, temperature-limited heating, or timed heating manner.

7. The structure according to claim 1, characterized in that, The control unit is also connected to the injection valve, bypass valve, heating reset unit and exhaust valve, and is used to allow the sample gas to enter the electrochemical sensor detection unit through the humidity buffer unit in the detection state, and to close or restrict the injection in the protection reset state, open the bypass dehumidification and exhaust, and perform dry gas reset and / or heating reset.

8. The structure according to claim 1, characterized in that, The control unit determines whether the protection threshold is exceeded based on the humidity state, droplet state, or baseline drift state of the electrochemical sensor detection unit. If the protection threshold is not exceeded, the sample gas is allowed to enter the electrochemical sensor detection unit and the detection result is output. If the protection threshold is exceeded, the sample injection is shut off, the bypass dehumidification is turned on, and dry gas reset and / or heating reset are performed.

9. A method for protecting and resetting the membrane surface of an exhaled gas electrochemical sensor employing the structure described in any one of claims 1 to 8, characterized in that, include: Wait for exhalation and collect humidity and droplet status; Determine whether the protection threshold has been exceeded based on humidity status, droplet status, or baseline drift status. When the protection threshold is not exceeded, the sample gas is allowed to enter the sensor and the detection result is output; when the protection threshold is exceeded, the sample injection is shut off and the bypass dehumidification is turned on, followed by the activation of dry gas reset and / or heating reset, and it is determined whether the baseline is restored.

10. The method according to claim 9, characterized in that, If the baseline is not restored, continue to perform dry gas reset and / or heating reset; when the baseline is restored to the preset range and the humidity and droplet states meet the detection access conditions, detection is allowed again; when the number of consecutive resets reaches the preset number and the detection access conditions are still not met, an abnormal prompt is output and the output of the target gas detection results is prohibited.

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