Electronic nose system for headspace detection
Through the innovative design of the membrane sampling cap and gas detection device, the problems of unstable sealing of sealed containers and inconsistent sensor responses were solved, achieving high-precision and high-stability headspace detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-16
- Publication Date
- 2026-04-14
AI Technical Summary
In the existing headspace detection process of electronic noses, the sealing of the sealed container is easily affected by the membrane rupture action, the headspace update rate and representativeness are unstable, the effective diameter of the sampling needle or narrow-diameter tube is too small, resulting in poor detection accuracy and repeatability, and the traditional air chamber structure causes inconsistent sensor response, affecting the comparability and repeatability of detection results.
A membrane-breaking sampling cap is used to dynamically seal the sealed container. Combined with the "upper cavity diversion and lower cavity mixing" structure of the gas detection device, a large gas sampling diameter is achieved through an annular clamping mechanism and a flexible connecting membrane. A micro gas pump is used to drive the gas into the detection device, and after diversion and mixing, it is detected again, ensuring the uniformity and stability of the sensor array.
It achieves low pressure drop and low retention gas sampling, improves detection accuracy and repeatability, enhances the response consistency of the sensor array and the comparability of detection results, and improves detection sensitivity and stability.
Smart Images
Figure CN121856476A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of electronic nose technology, and more particularly to an electronic nose system for headspace detection. Background Technology
[0002] Electronic noses use a multi-channel sensor array to "fingerprint" complex volatiles, and are widely used in scenarios such as food fermentation monitoring, pharmaceutical quality control, and environmental and packaging headspace detection.
[0003] Currently, the headspace detection process for electronic noses generally involves: first, manually tearing the membrane from a sealed container such as a beaker or reagent bottle; then, inserting a sampling needle or a narrow-diameter tubing; and finally, using an air pump to complete the headspace detection. In this process, the opening morphology of the sealed container is uncontrollable, the seal is easily affected by the membrane tearing action, the headspace update rate and representativeness are unstable, repeatability and comparability are poor, and the effective diameter of the sampling needle or narrow-diameter tubing is usually too small. To obtain the required volumetric flow rate, a higher pressure differential must be applied, which can easily lead to flow pulsation, delayed update, condensation / adsorption, and backflow risks. Furthermore, the poor sealing compatibility between the sampling needle / narrow-diameter tubing and the sealed container opening is not conducive to continuous or high-throughput applications, thus affecting detection accuracy. On the other hand, traditional electronic nasal air chambers are mostly straight-through or single-chamber structures, with the incoming flow approximating a piston flow. The flow field and concentration distribution within the chamber are greatly affected by the inlet conditions, making it difficult to form a stable uniform field with sufficient mixing. The flow conditions of the sensors near the inlet and near the outlet are significantly different, which can easily lead to inconsistent response intensity and response time of sensors at different locations. This makes the detection results highly sensitive to the flow rate setting and installation position, reducing the repeatability and comparability of the detection. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention provides an electronic nose system for headspace detection. This system uses a membrane-breaking sampling cap to dynamically seal and control the membrane breaking of a sealed container containing the gas to be tested. This results in a large gas sampling diameter and improved detection accuracy.
[0005] To solve the above problems, the present invention adopts the following technical solution:
[0006] An electronic nose system for headspace detection according to the present invention includes a processor, a gas detection device, a micro air pump, and a membrane-breaking sampling cover. The membrane-breaking sampling cover includes a cover body and an annular clamping mechanism. The annular clamping mechanism is located below the cover body and is sealed to the cover body through an annular flexible connecting membrane. The cover body is rotatable relative to the annular clamping mechanism. The cover body has an air inlet and an air outlet that penetrate the cover body. The bottom surface of the cover body has a membrane-breaking structure for piercing the sealing membrane of a container. The air outlet is connected to the air inlet of the gas detection device through the micro air pump. The gas detection device is electrically connected to the processor.
[0007] In this scheme, the sample to be tested is placed inside a container with a sealing film covering the top opening, and the sample generates volatile gas. During testing, the annular clamping mechanism of the membrane-breaking sampling cap is placed on the outside of the top of the container and tightened to lock the container opening. The air inlet on the cap is then connected to an external gas purification device. Next, the cap is pressed down to bring the membrane-breaking structure into contact with the sealing film at the container opening. The cap is then rotated to puncture a notch in the sealing film. Throughout the process, the annular clamping mechanism and the container maintain a static seal intact. Then, clean, dry air from the external gas purification device is introduced into the container through the air inlet on the cap. The gas to be tested in the headspace of the container flows out through the notch in the sealing film under the drive of a micro air pump and is smoothly delivered to the gas detection device. The gas detection device generates a response signal upon contact with the gas and sends it to the processor. The processor processes the response signal and outputs the test result.
[0008] Preferably, the membrane-breaking structure includes a plurality of conical spikes arranged at equal intervals along the circumference.
[0009] Preferably, the gas detection device includes a housing with a vertical cylindrical detection chamber inside. An air inlet is located at the top of the housing and communicates with the detection chamber via a gas guide chamber. An air outlet communicating with the detection chamber is located at the bottom of the housing. A horizontal partition is provided inside the detection chamber, dividing it into an upper chamber and a lower chamber. Three vertical partitions are provided inside the upper chamber, dividing it into three sub-chambers. Each sub-chamber contains a first gas sensor array. Three second gas sensor arrays are provided in the lower chamber, each corresponding to one of the three sub-chambers. The second sensor arrays are located below their respective sub-chambers. Multiple ventilation holes are provided on the horizontal partitions. The first and second sensor arrays are electrically connected to a processor.
[0010] The gas to be tested enters through the air inlet at the top of the casing. After passing through the air guide chamber, it is divided into three directional sub-gas flows by three vertical baffles and flows through the corresponding sub-gas chambers. The corresponding first gas sensor array performs the first detection. Afterward, the three directional sub-gas flows enter the lower gas chamber through the vent group. The multiple perforated jets of the vent group generate uniformly distributed small-scale vortices, thereby achieving enhanced mixing. The mixed gas is detected for the second time by the second gas sensor array. The detected exhaust gas is discharged from the air outlet at the bottom of the casing. The response signals generated by the contact between the first gas sensor array, the second sensor array and the gas to be tested are sent to the processor.
[0011] Preferably, the air guide cavity is in the shape of an inverted funnel.
[0012] Preferably, both the air inlet and the air outlet are straight pipes and coaxial.
[0013] Preferably, the first gas sensor array needs to meet the following condition: the normalized sensitivity S of the first gas sensor array u Not greater than the normalized sensitivity S of the second gas sensor array l 0.3 times; at the transient peak concentration C in the sub-gas chamber peak No saturation occurs at 1.3 times the maximum value and the output does not exceed 0.8FS; under flow or concentration step disturbance conditions, the maximum overshoot of the first gas sensor array output signal does not exceed 5% of the full-scale output, and the baseline drift amplitude after recovery to steady state does not exceed 3% of the full-scale output. 90 ≤20s, where T 90 This is the time required from the start of the step disturbance until the output reaches 90% of its steady-state change.
[0014] Preferably, the second gas sensor array must meet the following condition: under a signal-to-noise ratio (SNR) of 3, the detection limit (LOD) must be [value missing]. l ≤ Lower chamber steady-state representative concentration C ref 5%; at a concentration of 0.2°C ref ~2.0C ref Within the range, the linear correlation coefficient R between the output signal and the actual concentration 2 ≥0.98; Normalized sensitivity S of the second gas sensor array l Normalized sensitivity S of the first gas sensor array u The ratio of S l / S u ≥3; Under conditions of step disturbances in flow rate or concentration, T 90 ≤15s, where T 90 The time required for the output to reach 90% of its steady-state change from the start of the step disturbance; the coefficient of variation (CV) is no greater than 0.10, and the coefficient of variation (CV) is the ratio of the standard deviation to the average value of the normalized response collected by all gas sensors in the second gas sensor array.
[0015] Preferably, a connecting column is provided at the center of the top surface of the horizontal partition, and the three vertical partitions are respectively connected to the connecting column. The included angle between adjacent vertical partitions is 120 degrees. The bottom of the vertical partition is connected to the horizontal partition, and the outer side of the vertical partition is connected to the inner wall of the detection cavity.
[0016] Preferably, the horizontal partition is circular, and has 3*n groups of vent holes evenly spaced along its circumference. Each group of vent holes includes multiple vent holes arranged radially. The horizontal partition is divided into three ventilation zones by three vertical partitions, and each ventilation zone has n groups of vent holes. n is a positive integer, and the opening ratio of the horizontal partition is 15%-45%.
[0017] Preferably, the top of the connecting column is provided with a conical guide block, and the top of the vertical partition is provided with symmetrical guide slopes on the front and rear sides. The guide slopes are inclined inward from bottom to top, and the tops of the two guide slopes are connected.
[0018] The beneficial effects of this invention are: (1) By using a membrane-breaking sampling cap to dynamically seal and control the membrane breaking of a sealed container containing the gas to be tested, the gas sampling diameter is large, achieving low pressure drop and low retention unidirectional renewal, avoiding inlet bias and leakage caused by abrupt changes in the cross-section of the fine sampling needle and the coarse cavity, thus improving detection accuracy. (2) The detection chamber is a two-section structure of "upper cavity splitting and lower cavity mixing". The first gas sensor array and the second gas sensor array respectively obtain differentiated stimulation and full homogenization. The gas characteristics detected by the two gas sensor arrays are complementary, thus improving detection accuracy. Attached Figure Description
[0019] Figure 1 This is a schematic diagram of the structure of the membrane-breaking sampling cap;
[0020] Figure 2 This is a bottom view of the cover.
[0021] Figure 3 This is a schematic diagram of the ring-shaped clamping mechanism;
[0022] Figure 4 This is a schematic diagram of the internal structure of a gas detection device;
[0023] Figure 5 This is a perspective view of the gas detection device;
[0024] Figure 6 This is a simulation result of the XY profile of the internal flow field distribution of the gas detection device;
[0025] Figure 7 This is a simulated cloud map of the pressure in the XY cross section inside the gas detection device.
[0026] In the diagram: 1. Cover, 2. Annular clamping mechanism, 3. Flexible connecting membrane, 4. Air inlet, 5. Air outlet, 6. Conical spike, 7. Shell, 8. Detection chamber, 9. Air inlet, 10. Air guide chamber, 11. Air outlet, 12. Horizontal partition, 13. Upper air chamber, 14. Lower air chamber, 15. Vertical partition, 16. Sub-air chamber, 17. First gas sensor array, 18. Second gas sensor array, 19. Connecting column, 20. Vent hole, 21. Guide block, 22. Guide slope. Detailed Implementation
[0027] The technical solution of the present invention will be further described in detail below through embodiments and in conjunction with the accompanying drawings.
[0028] Example: An electronic nose system for headspace detection in this example, such as... Figures 1 to 5 As shown, the device includes a processor, a gas detection device, a micro air pump, and a membrane-breaking sampling cover. The membrane-breaking sampling cover includes a cover body 1 and an annular clamping mechanism 2. The annular clamping mechanism 2 is located below the cover body 1 and is sealed to the cover body 1 through an annular flexible connecting membrane 3. The cover body 1 can rotate relative to the annular clamping mechanism 2. The cover body 1 is provided with an air inlet 4 and an air outlet 5 that penetrate the cover body 1. The air inlet 4 and the air outlet 5 are symmetrically arranged on the left and right sides of the cover body 1. The bottom surface of the cover body 1 is provided with a membrane-breaking structure for piercing the container sealing membrane. The membrane-breaking structure includes four conical spikes 6 arranged at equal intervals along the circumference. The air outlet 5 is connected to the air inlet 9 of the gas detection device through the micro air pump.
[0029] The gas detection device includes a housing 7, within which a vertically cylindrical detection chamber 8 is provided. An air inlet 9 is located at the top of the housing 7, communicating with the detection chamber 8 via a guide chamber 10, which is shaped like an inverted funnel. An air outlet 11, communicating with the detection chamber 8, is located at the bottom of the housing 7. A horizontal partition 12 is provided within the detection chamber 8, dividing it into an upper chamber 13 and a lower chamber 14. The upper chamber 13 contains three vertical partitions 15, which equally divide it into three sub-chambers 16. Each sub-chamber 16 contains a first gas sensor array 17. The lower chamber 14 contains three second gas sensor arrays 18, with each of the three second gas sensor arrays 18 corresponding to one of the three sub-chambers 16. Correspondingly, the second sensor array 18 is located below the corresponding sub-gas chamber 16. A connecting column 19 is provided at the center of the top surface of the horizontal partition 12. Three vertical partitions 15 are respectively connected to the connecting column 19. The included angle between adjacent vertical partitions 15 is 120 degrees. The bottom of the vertical partition 15 is connected to the horizontal partition 12. The outer side of the vertical partition 15 is connected to the inner sidewall of the detection chamber 8. The horizontal partition 12 is circular. 3*n ventilation hole groups are equally spaced along the circumference of the horizontal partition 12. Each ventilation hole group includes multiple ventilation holes 20 arranged radially. The horizontal partition 12 is divided into three ventilation zones by the three vertical partitions 15. Each ventilation zone has n ventilation hole groups, where n is a positive integer. The first gas sensor array 17 and the second sensor array 18 are electrically connected to the processor.
[0030] The top of the connecting column 19 is provided with a conical guide block 21, and the top of the vertical partition 15 is provided with symmetrical guide slopes 22 on the front and rear sides. The guide slopes 22 are inclined inward from bottom to top, and the tops of the two guide slopes 22 are connected.
[0031] The vertical height of the conical spike 6 is 4-8mm. The flexible connecting membrane is made of polytetrafluoroethylene. The upper and lower sides of the flexible connecting membrane are bonded and fixed to the cover and the annular clamping mechanism respectively with chemical corrosion resistant sealant to form a reliable dynamic sealing structure. The flexible connecting membrane allows the cover to rotate relative to the annular clamping mechanism while maintaining the sealing of the sampling space.
[0032] Both the inlet 9 and the outlet 11 are straight tubes and coaxial, with a height of 10 mm and an inner diameter of 3 mm. They are used to stabilize the inflow velocity profile, reduce turbulence, and provide repeatable boundary conditions for subsequent flow field organization.
[0033] The horizontal baffle 12 is 2mm thick, with a vent diameter of 2mm, and an opening ratio of 15%-45%. In this embodiment, the opening ratio of the horizontal baffle is 30%, and at a rated flow rate of 1.0L / min, the Reynolds number Re of a single orifice is... h The value is 800, which ensures that continuous small-scale vortices can be effectively generated in the lower air chamber when the gas passes through, so as to achieve turbulent mixing.
[0034] The vertical partition 15 is 40mm high, and the first gas sensor array 17 is located at the center of the inner wall of the corresponding sub-gas chamber 16.
[0035] The first gas sensor array 17 must meet the following condition: the normalized sensitivity S of the first gas sensor array u (Unit: FS / ppm, where FS is the full-scale output value of the gas sensor) is not greater than the normalized sensitivity S of the second gas sensor array. l 0.3 times (i.e., S) u ≤0.3S l ); at the transient peak concentration C in the sub-gas chamber peak No saturation occurs at 1.3 times the value and the output does not exceed 0.8FS; under flow or concentration step disturbance conditions, the maximum overshoot of the first gas sensor array output signal does not exceed 5% of the full-scale output (i.e., overshoot ≤ 5%FS), and the baseline drift amplitude after recovering to steady state does not exceed 3% of the full-scale output (i.e., baseline drift ≤ 3%FS), T 90 ≤20s, where T 90 This is the time required from the start of a step disturbance until the output reaches 90% of its steady-state change. In other words, the gas sensors in the first gas sensor array are selected with a wide measurement range and strong resistance to transient shocks. The first gas sensor array is used to acquire the spatiotemporal distribution characteristics of gas in different sub-chambers under split-flow conditions and to suppress saturation distortion caused by transient spikes.
[0036] The second gas sensor array 18 must meet the following condition: under the condition of signal-to-noise ratio (SNR) = 3, the measured detection limit (LOD) must be [value missing].l ≤ Lower chamber steady-state representative concentration C ref 5%; at a concentration of 0.2°C ref ~2.0C ref Within the range, the linear correlation coefficient R between the output signal and the actual concentration 2 ≥0.98; Normalized sensitivity S of the second gas sensor array l Normalized sensitivity S of the first gas sensor array u The ratio of S l / S u ≥3; Under conditions of step disturbances in flow rate or concentration, T 90 ≤15s, where T 90 This is the time required for the output to reach 90% of its steady-state change from the start of a step disturbance. The coefficient of variation (CV), calculated based on the normalized responses collected by all gas sensors in the second gas sensor array, is no greater than 0.10. The CV is the ratio of the standard deviation to the average value of the normalized responses collected by all gas sensors in the second gas sensor array. This indicates that the gas sensors in the second gas sensor array are selected for their high sensitivity and low detection limit. The second gas sensor array is placed in a well-mixed homogeneous field to accurately estimate the average composition and trace components of the gas, improving detection sensitivity and quantitative accuracy.
[0037] The upper air chamber receives the incoming flow directly and has a steep gradient. The use of a first gas sensor array can avoid overshoot and retain dynamic clues such as arrival time / rise edge. The lower air chamber forms small-scale vortices after the jet is perforated by a horizontal baffle and prolongs the near-wall contact time. A second gas sensor array is used to amplify minute differences and improve the signal-to-noise ratio under uniform field.
[0038] In this procedure, the sample to be tested is placed in a container with a sealing film covering the top opening, and the sample to be tested generates volatile gas. During testing, the annular clamping mechanism of the membrane-breaking sampling cap is placed on the outside of the top of the container. The annular clamping mechanism is tightened to lock the container opening, and the air inlet on the cap is connected to an external gas purification device. The air outlet at the bottom of the casing is connected to an activated carbon adsorption tank. Next, the cap is pressed down so that the four conical spikes contact the sealing membrane at the container opening. The cap is rotated so that the conical spikes pierce four consecutive, centrally symmetrical arc-shaped cuts in the sealing membrane, forming a regular, pinwheel-shaped opening. Throughout the process, the annular clamping mechanism and the container maintain a static seal intact. Then, the external gas purification device outputs clean, dry air at a constant flow rate of 1.5 L / min, which is introduced into the container through the air inlet on the cap. The test gas in the headspace of the container flows out through the gap in the sealing membrane under the drive of a micro-pump, enters through the air inlet at the top of the casing, and after passing through the air guide chamber, is divided into three directional sub-gas flows by three vertical baffles, flowing through their corresponding sub-gas chambers. The flow-dividing effect of the three vertical baffles is as follows: Figure 6 As shown, the velocity streamlines are uniformly split into three beams by a vertical baffle in the upper chamber, with an average velocity deviation of ≤8% across the three channels. The corresponding first gas sensor array performs the initial detection. Subsequently, the three directional sub-gas streams enter the lower chamber through perforated jets formed by ventilation holes. The velocity difference between the jets behind each hole and the surrounding low-speed gas drives entrainment and diffusion. The jets merge and combine in the lower chamber, generating small-scale flow structures, thereby enhancing mixing. The pressure field is as follows: Figure 7 As shown, there is a visible pressure drop on both sides of the horizontal baffle, while the pressure distribution in the lower chamber tends to be uniform, which is beneficial to the uniformity of flow at the second gas sensor array. The mixed gas is detected for the second time by the second gas sensor array. The detected exhaust gas is discharged from the outlet at the bottom of the shell to the activated carbon adsorption tank. The response signals generated by the first gas sensor array, the second sensor array and the gas to be tested are sent to the processor. The processor processes the response signals and outputs the detection results.
[0039] The six signals output from the three first gas sensor arrays and the three second gas sensor arrays are sent to the processor via a 24-bit high-precision ADC acquisition card. The processor first performs baseline correction and environmental temperature and humidity compensation, then extracts various feature values of transient and steady-state responses, and finally uses a pre-trained support vector machine (SVM) model to perform odor classification or concentration prediction. The detection results are displayed through a human-machine interface.
[0040] The gas detection device, through its "front-end diversion and rear-end mixing" design, can simultaneously improve the stimulation uniformity and mixing sufficiency of the sensor array, thereby enhancing sensitivity, stability, and recognition performance.
Claims
1. An electronic nose system for headspace detection, characterized in that, The device includes a processor, a gas detection device, a micro air pump, and a membrane-breaking sampling cover. The membrane-breaking sampling cover includes a cover body (1) and an annular clamping mechanism (2). The annular clamping mechanism (2) is located below the cover body (1). The annular clamping mechanism (2) and the cover body (1) are sealed together by an annular flexible connecting membrane (3). The cover body (1) can rotate relative to the annular clamping mechanism (2). The cover body (1) is provided with an air inlet (4) and an air outlet (5) that penetrate the cover body (1). The bottom surface of the cover body (1) is provided with a membrane-breaking structure for piercing the sealing membrane of the container. The air outlet (5) is connected to the air inlet (9) of the gas detection device through the micro air pump. The gas detection device is electrically connected to the processor.
2. The electronic nose system for headspace detection according to claim 1, characterized in that, The membrane-breaking structure includes multiple conical spikes (6) arranged at equal intervals along the circumference.
3. The electronic nose system for headspace detection according to claim 1, characterized in that, The gas detection device includes a housing (7), inside which is a vertical cylindrical detection chamber (8). An air inlet (9) is located at the top of the housing (7), communicating with the detection chamber (8) via a gas guide chamber (10). An air outlet (11) communicating with the detection chamber (8) is located at the bottom of the housing (7). A horizontal partition (12) is located inside the detection chamber (8), dividing it into an upper chamber (13) and a lower chamber (14). The upper chamber (13) contains three vertical partitions (15). The gas chamber (13) is divided into three sub-gas chambers (16) by three vertical partitions (15). Each sub-gas chamber (16) is equipped with a first gas sensor array (17). The lower gas chamber (14) is equipped with three second gas sensor arrays (18). The three second gas sensor arrays (18) correspond one-to-one with the three sub-gas chambers (16). The second sensor arrays (18) are located below the corresponding sub-gas chambers (16). The horizontal partition (12) is equipped with multiple groups of ventilation holes. The first gas sensor array (17) and the second sensor arrays (18) are electrically connected to the processor.
4. An electronic nose system for headspace detection according to claim 3, characterized in that, The air guide cavity (10) is in the shape of an inverted funnel.
5. An electronic nose system for headspace detection according to claim 3, characterized in that, The air inlet (9) and air outlet (11) are both straight pipes and coaxial.
6. An electronic nose system for headspace detection according to claim 3, characterized in that, The first gas sensor array (17) must meet the following condition: the normalized sensitivity S of the first gas sensor array u Not greater than the normalized sensitivity S of the second gas sensor array l 0.3 times; at the transient peak concentration C in the sub-gas chamber peak No saturation occurs at 1.3 times the maximum value and the output does not exceed 0.8FS; under flow or concentration step disturbance conditions, the maximum overshoot of the first gas sensor array output signal does not exceed 5% of the full-scale output, and the baseline drift amplitude after recovery to steady state does not exceed 3% of the full-scale output. 90 ≤20s, where T 90 This is the time required from the start of the step disturbance until the output reaches 90% of its steady-state change.
7. An electronic nose system for headspace detection according to claim 3, characterized in that, The second gas sensor array (18) must meet the following condition: under the condition of signal-to-noise ratio (SNR) = 3, the detection limit (LOD) must be [value missing]. l ≤ Lower chamber steady-state representative concentration C ref 5%; at a concentration of 0.2°C ref ~2.0C ref Within the range, the linear correlation coefficient R between the output signal and the actual concentration 2 ≥0.98; Normalized sensitivity S of the second gas sensor array l Normalized sensitivity S of the first gas sensor array u The ratio of S l / S u ≥3; Under conditions of step disturbances in flow rate or concentration, T 90 ≤15s, where T 90 The time required for the output to reach 90% of its steady-state change from the start of the step disturbance; the coefficient of variation (CV) is no greater than 0.10, and the coefficient of variation (CV) is the ratio of the standard deviation to the average value of the normalized response collected by all gas sensors in the second gas sensor array.
8. An electronic nose system for headspace detection according to claim 3, characterized in that, The horizontal partition (12) has a connecting column (19) at the center of its top surface. The three vertical partitions (15) are connected to the connecting column (19) respectively. The included angle between adjacent vertical partitions (15) is 120 degrees. The bottom of the vertical partition (15) is connected to the horizontal partition (12). The outer side of the vertical partition (15) is connected to the inner wall of the detection cavity (8).
9. An electronic nose system for headspace detection according to claim 8, characterized in that, The horizontal partition (12) is circular, and 3*n ventilation hole groups are provided at equal intervals along the circumference of the horizontal partition (12). The ventilation hole group includes multiple ventilation holes (20) arranged radially. The horizontal partition (12) is divided into three ventilation zones by three vertical partitions (15), and each ventilation zone has n ventilation hole groups.
10. An electronic nose system for headspace detection according to claim 8, characterized in that, The top of the connecting column (19) is provided with a conical guide block, and the top of the vertical partition (15) is provided with symmetrical guide slopes (22) on the front and back sides. The guide slopes (22) are inclined inward from bottom to top, and the tops of the two guide slopes (22) are connected.