Quantitative sample injection system and method of electronic nose

Abstract

The invention discloses a quantitative sample introduction system and method of an electronic nose. The quantitative sample introduction system comprises a sample quantitative extraction device, a sample introduction cabin, a heating device and an air blowing pump pipeline, the sample quantitative extraction device is used for extracting a VOC sample with a target volume; the sample introduction cabin is mechanically connected with the sensor induction cabin through a KF16 vacuum clamp and is in gas circuit connection with the sensor induction cabin through a blowing pump pipeline; after a VOC sample is extracted by the sample injection needle, the sample injection needle is inserted into the sample injection port; the heating device comprises a heating sheet and a heating controller; the heating sheet is attached to the bottom of the sample injection cabin, and the heating controller controls the target temperature of the heating sheet so as to promote rapid volatilization of the VOC sample in the sample injection cabin. According to the invention, the silicone rubber with good contractility is used as the material of the sample injection port, and the contraction pre-tightening force is applied in the installation process, so that the silicone rubber can still tighten the sample injection port after the silicone rubber is punctured by a sample injection needle for sample injection, and the leakproofness of an electronic nose experimental environment is ensured.

Description

Technical Field

[0001] This invention belongs to the field of electronic nose technology, specifically relating to a quantitative sample introduction system and method for an electronic nose. Background Technology

[0002] An electronic nose mainly consists of three parts: a gas sensor array, a signal processing module, and a pattern recognition module. Before the gas sensor array detects the gas, the gas sample needs to be diffused into the sensor chamber of the electronic nose; therefore, gas sample introduction forms the basis of the electronic nose's operation. However, volatile organic compounds (VOCs) are mainly in liquid form, making quantitative sample introduction of their vaporized gas samples quite difficult. Currently, headspace sampling is the primary method for VOC gas introduction. Headspace sampling introduces VOC gas by collecting saturated VOC vapor above the VOC. Headspace sampling typically employs two methods to collect and inject gaseous VOCs: static headspace sampling and dynamic headspace sampling.

[0003] Static headspace sampling uses a sampling needle to first extract a certain amount of VOC headspace vapor, which is then injected into the gas sensor chamber. The concentration of gaseous VOCs is measured by the volume of the extracted headspace vapor through the scale of the needle. However, this method cannot accurately measure the concentration of the extracted gaseous VOCs because the headspace contains not only VOC gas but also impurities such as air. Furthermore, the injection process into the sensor chamber can lead to leakage, allowing more gaseous impurities to enter the sensor chamber.

[0004] Dynamic headspace sampling (VOC) relies on a pump or high pressure to force carrier gas through the VOC headspace, loading VOC vapor into the gas sensor chamber. The concentration of gaseous VOCs is controlled by varying carrier gas flow rates. This method effectively addresses the leakage problem; however, because the evaporation rate of VOCs in the carrier gas flow is influenced by various factors and the actual evaporation rate cannot be measured, the VOC concentration in the carrier gas remains inaccurate. Furthermore, controlling the carrier gas flow rate cannot precisely control the VOC concentration. Summary of the Invention

[0005] To overcome the shortcomings of existing technologies, this invention provides a quantitative sample introduction system and method for an electronic nose, including a sample quantitative extraction device, an injection chamber, a heating device, and an air pump pipeline. The sample quantitative extraction device extracts a target volume of VOC sample. The injection chamber is mechanically connected to the sensor chamber via a KF16 vacuum clamp and connected to the sensor chamber via the air pump pipeline. After extracting the VOC sample, the injection needle is inserted into the injection port. The heating device includes a heating element and a heating controller. The heating element is attached to the bottom of the injection chamber, and the heating controller controls the target temperature of the heating element to promote the rapid evaporation of the VOC sample in the injection chamber. This invention uses silicone rubber with good shrinkage properties as the material for the injection port and applies a shrinkage pre-tightening force during installation, so that even after the silicone rubber is punctured by the injection needle for sample injection, the injection port can still be tightened, ensuring the airtightness of the electronic nose experimental environment.

[0006] The technical solution adopted by this invention to solve its technical problem is as follows: A quantitative sample introduction system for an electronic nose includes: a sample quantitative extraction device, a sample introduction chamber, a heating device, and an air blowing pump pipeline; The sample quantitative extraction device includes a quantitative extraction pump and an injection needle; by using the quantitative extraction pump, setting the range, and using the injection needle with the corresponding range, the target volume of liquid to be extracted is set on the extraction pump, and the target volume of VOC sample can be repeatedly extracted. The sample inlet chamber is a hollow stainless steel device, including an inlet, a slide plate, an observation window, a light source, a KF16 vacuum clamp, and a fixing and mounting device. The sample injection chamber is mechanically connected to the sensor sensing chamber via a KF16 vacuum clamp; the sample injection chamber is connected to the sensor sensing chamber via an air pump pipeline. The injection port is located at the top of the injection chamber; after the VOC sample is extracted, the injection needle is inserted into the injection port. The slide plate is installed between the inlet and the bottom of the injection chamber. The VOC sample flows on the slide plate and leaves traces. The increased surface area accelerates the volatilization process. The observation window is used to observe the situation inside the chamber; the light source is connected to a fixed rod outside the sample injection chamber through a fixed installation device, and the light emitted by the light source enters the sample injection chamber through the observation window; The heating device includes a heating element and a heating controller; the heating element is attached to the bottom of the sample injection chamber, and the heating controller controls the target temperature of the heating element to promote the rapid volatilization of VOC samples in the sample injection chamber.

[0007] Preferably, the observation window is made of quartz glass and is sealed to a stainless steel ring via inner and outer rubber rings.

[0008] Preferably, the injection port includes a silicone rubber gasket, a nut, and a top rubber ring; the nut presses against the silicone rubber gasket and forms a shrinkage preload, and the top rubber ring further presses against the nut, ensuring the sealing of the injection port.

[0009] Preferably, the blowing pump pipeline includes a blowing pump and a blowing pipeline; the blowing pump is located in the sensor sensing chamber, one end of the blowing pipeline is connected to the blowing pump, and the other end extends into the sample injection chamber; the blowing pump blows the gas in the sensor sensing chamber into the sample injection chamber through the blowing pipeline, thereby pressing the gaseous VOC in the sample injection chamber into the sensor sensing chamber, and after a certain period of time, the quantitative injection of gaseous VOC in the sample injection chamber into the sensor sensing chamber is achieved; the blowing pipeline 22 uses a 5*8mm transparent rubber tube with a length of 1 meter.

[0010] Preferably, the injection needle is a small-diameter needle with a side-opening pointed tip to reduce the size of the puncture site and ensure airtightness.

[0011] Preferably, after the VOC sample is injected into the injection chamber by the injection needle, it is directly dripped onto the slide plate. The VOC sample slides down to the bottom under the action of gravity, leaving scratches and gradually spreading out.

[0012] Preferably, the air pump is a high-pressure, high-flow type air pump.

[0013] Preferably, a fan is provided inside the sensor chamber to ensure that the gas is evenly distributed within the sensor chamber.

[0014] A quantitative sample introduction method for an electronic nose, the specific steps of which are as follows: Step 1: Based on the required concentration and the size of the sensor chamber, obtain the required VOC volume; place the injection needle on the quantitative extraction pump, set the corresponding volume on the quantitative extraction pump, insert the injection needle tip into the VOC liquid, and the quantitative extraction pump draws the VOC liquid into the injection needle tube at a uniform speed and quantity, then remove the injection needle from the quantitative extraction pump. Step 2: Insert the injection needle into the injection port, inject the VOC liquid, and then quickly pull it out and cover it with the top rubber ring; wait for the VOC liquid to evaporate on the slide plate. At this time, the VOC liquid becomes VOC gas and exists in the injection chamber. Step 3: Turn on the air pump, wait for the concentrations of VOCs in the sample injection chamber and the sensor sensing chamber to reach equilibrium, then turn off the air pump; Step 4: Turn on the fan inside the sensor chamber, wait 5 minutes, and then turn off the fan; the odor signal detected by the gas sensor inside the sensor chamber will remain stable at this time.

[0015] The beneficial effects of this invention are as follows: This invention achieves precise VOC gas sample injection by quantitatively extracting VOC liquid, injecting it into the sample inlet chamber, where it rapidly evaporates on a slide plate. The evaporated VOC gas then enters the sensor chamber through a blowing tube. In this invention, silicone rubber with good shrinkage properties is used as the material for the inlet, and a shrinkage pre-tightening force is applied during installation. This ensures that even after the silicone rubber is punctured by the injection needle, it can still tighten the inlet, guaranteeing the airtightness of the electronic nose experimental environment. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the electronic nose VOC quantitative injection system of the present invention; Figure 2 This is a schematic diagram of the sample inlet chamber structure of the sample inlet system in this invention; Figure 3 This is a side view of the sample inlet chamber of the sample inlet system in this invention; Figure 4 This is a flowchart of the electronic nose VOC quantitative injection method of the present invention.

[0017] Reference numerals: 1. Screw; 2. Slide plate; 3. Sample inlet chamber; 4. Stainless steel ring; 7. Sample inlet; 8. Fixing rod; 9. Observation window; 10. KF16 vacuum clamp; 15. Heating element; 16. Fixing and mounting device; 17. Flashlight; 20. Sensor induction chamber; 21. Air blowing pump; 22. Air blowing pipeline; 23. Quantitative extraction pump; 24. Sample injection needle; 25. Fan. Detailed Implementation

[0018] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] The purpose of this invention is to design a precise VOC gas injection system while ensuring a sealed experimental environment for electronic nose experiments. The main problems this invention aims to solve are how to maintain a sealed environment after VOC gas injection and how to accurately measure the concentration of VOC gas quantitatively.

[0020] The sample introduction system of the present invention mainly includes: a sample quantitative extraction device, a sample introduction chamber, a heating device, and an air blowing pump pipeline.

[0021] The sample quantification device includes a quantitative extraction pump and an injection needle. By using the quantitative extraction pump, setting the range, and using an analytical injection needle with the corresponding range, and setting the target volume of liquid to be extracted on the extraction pump, the target volume of VOC sample can be accurately and repeatedly extracted.

[0022] The sample injection chamber is a hollow stainless steel device. It includes a rubber inlet, a slide plate, a glass observation window, and a light source. The rubber inlet is used by the injection needle to inject the target volume of VOC liquid; after injection, the inlet remains sealed even after the analytical injection needle is withdrawn. The VOC sample flows along the slide plate, leaving traces; the increased surface area accelerates the evaporation process. The light source illuminates the interior of the sample injection chamber through the observation window, allowing observation of the degree of VOC evaporation. Connecting tubing connects the sample injection chamber to the sensor chamber.

[0023] The air blowing pump pipeline includes the air blowing pump and its piping. The air blowing pump is located in the sensor sensing chamber, and one end of the air blowing pipeline is connected to the air blowing pump, while the other end extends into the sample injection chamber. The air blowing pump blows gas from the sensor sensing chamber into the sample injection chamber through the air blowing pipeline, thereby pressurizing the gaseous VOCs in the sample injection chamber into the sensor sensing chamber. After a certain period of time, the quantitative injection of gaseous VOCs from the sample injection chamber into the sensor sensing chamber can be achieved.

[0024] The quantitative extraction pump can be adapted to analytical injection needles with various ranges to achieve quantitative extraction of VOC liquids of different volumes. By selecting high-precision extraction pumps and injection needles, accurate extraction of VOCs can be achieved, thereby enabling accurate conversion of VOC concentration.

[0025] The injection needle is a small-diameter needle with a side opening and a pointed tip to reduce the size of the puncture site and ensure airtightness.

[0026] To increase the evaporation rate of VOC liquids, the volume of the sample injection chamber should be relatively large.

[0027] The sample injection chamber is composed of stainless steel and glass, with a sealing ring connecting the stainless steel and glass to achieve good sealing.

[0028] The sample injection chamber contains observation windows at multiple angles (such as the front and sides) to facilitate observation and confirmation of the evaporation progress.

[0029] The injection port consists of three parts: a rubber gasket, a nut, and a top rubber ring. The top rubber ring connects tightly with the nut, serving as a second seal for the injection port and further ensuring the injection chamber's tightness. The injection port uses a type of rubber with good shrinkage properties. The nut secures the silicone rubber to the injection chamber, ensuring a good seal. The rubber placement area features a shrinkage preload application structure. After the nut is tightened, an inward shrinkage preload is applied, ensuring that even if punctured and removed by the injection needle, it remains tight and without noticeable holes, maintaining the purity of the gas environment inside the injection chamber.

[0030] The slide plate is installed between the rubber injection port and the bottom of the injection chamber. After the VOC liquid is injected into the injection chamber by the injection needle, it drips directly onto the slide plate. The VOC liquid slides down to the bottom under the action of gravity, leaving scratches and gradually spreading out.

[0031] The sample injection chamber heating device is designed with an external heating element, the temperature of which is controlled by a heating controller. When high-boiling-point or large-volume VOC liquids enter the sample injection chamber, the heating element can be used to accelerate the evaporation of the liquid.

[0032] To improve the gas exchange rate between the sample introduction chamber and the sensor sensing chamber, a high-pressure, high-flow-rate gas pump is selected. The gas pump is located inside the sensor sensing chamber. Additionally, a fan is installed inside the sensor sensing chamber to ensure uniform gas distribution within the chamber.

[0033] Based on this system, the present invention also provides an electronic nose VOC quantitative injection method, the specific steps of which are as follows: Step 1: Determine the required VOC volume based on the required concentration and the size of the sensor chamber. Place the injection needle on the quantitative extraction pump, set the appropriate volume on the pump, and insert the injection needle tip into the VOC liquid. The quantitative extraction pump will draw the VOC liquid into the injection needle tube at a uniform rate and in a quantitative manner. Remove the injection needle from the quantitative extraction pump. Step 2: Insert the injection needle into the injection port, inject the VOC liquid, and then quickly pull it out and replace the top rubber ring. Wait for the VOC liquid to evaporate and disappear on the slide plate. At this point, the VOC liquid has become VOC gas and exists in the injection chamber.

[0034] Step 3: Turn on the air pump, wait for the VOC gas concentration in the sample injection chamber and the sensor sensing chamber to reach equilibrium, and then turn off the air pump.

[0035] Step 4: Turn on the fan inside the sensor chamber, wait 5 minutes, then turn it off. The odor signal detected by the gas sensor inside the sensor chamber will remain stable at this time.

[0036] Example: Figure 1 This is a schematic diagram of an electronic nose VOC quantitative sample introduction system provided in an embodiment of the present invention. The system mainly consists of a quantitative extraction pump 23, a sample introduction chamber 3, a heating device, and an air blowing pump pipeline. After the sample is extracted, the injection needle 24 is inserted into the sample introduction chamber 3. The air blowing pump 21 and part of the air blowing pipeline 22 are located in the sensor sensing chamber 20, and the fan 25 is also located in the sensor sensing chamber 20. The sensor sensing chamber 20 is connected to the sample introduction chamber 3 via the air blowing pipeline 22. The air blowing pipeline 22 uses a 5*8mm transparent rubber tube and is 1 meter long.

[0037] Figure 2 This is a schematic diagram of the sample injection chamber 3 in the quantitative sample injection system of the present invention. Figure 3This is a side view of the sample injection chamber 3 in the quantitative sample injection system of the present invention. The mechanical connection between the sample injection chamber 3 and the sensor sensing chamber 20 is mainly through a KF16 vacuum clamp 10. The sample inlet 7 of the sample injection chamber 3 is located at the top of the entire device. The sample inlet 7 consists of three parts: a silicone rubber gasket, a nut, and a top rubber ring. The nut compresses the silicone rubber gasket and forms a shrinkage preload, while the top rubber ring further compresses the nut, ensuring the sealing of the sample inlet. A slide plate 2 is installed between the sample inlet and the bottom of the sample injection chamber. A heating element 15 is attached to the bottom of the sample injection chamber, which can control the heating element at a suitable target temperature to promote the rapid volatilization of VOCs inside the sample injection chamber 3.

[0038] The sample injection chamber 3 allows observation of its interior from the front and sides via the observation window 9. The observation window 9 is primarily made of quartz glass and is sealed to a stainless steel ring 4 via inner and outer rubber rings. Eight screws 1 secure the stainless steel ring and quartz glass to the sample injection chamber 3. A flashlight 17 serves as the light source and is connected to a fixing rod 8 via a mounting device 16. The light from the flashlight 17 enters the sample injection chamber 3 through the side observation window 9.

[0039] Based on the above quantitative injection system, this embodiment provides an electronic nose VOC quantitative injection method. (Refer to...) Figure 4 The method includes the following steps: Step S1: Determine the required VOC volume based on the required concentration and the size of the sensor chamber. Place the injection needle on the quantitative extraction pump, set the corresponding volume on the pump, and insert the injection needle tip into the VOC liquid. The quantitative extraction pump will draw the VOC liquid into the injection needle tube at a uniform rate and in a quantitative manner. Remove the injection needle from the quantitative extraction pump. Step S2: Insert the injection needle into the injection port, inject the VOC liquid, and then quickly pull it out and replace the top rubber ring. Wait for the VOC liquid to evaporate and disappear on the slide plate. At this point, the VOC liquid has become VOC gas and exists in the injection chamber.

[0040] Step S3: Turn on the air pump, wait for the VOC gas concentration in the sample injection chamber and the sensor sensing chamber to reach equilibrium, and then turn off the air pump.

[0041] Step S4: Turn on the fan, wait 5 minutes, then turn it off. The odor signal detected by the gas sensor in the sensor chamber will remain stable at this time.

[0042] Therefore, by employing the VOC quantitative sampling device and design method provided in this embodiment, and through a rationally designed device structure, VOC liquid is quantitatively extracted, injected into the sampling chamber, and rapidly evaporates on the slide plate. The evaporated VOC gas then enters the sensor sensing chamber through the blowing pipe, achieving precise VOC gas sample injection. In this embodiment, silicone rubber is used as the material for the injection port, and a shrinkage pre-tightening force is applied, allowing the injection port to be tightened even after injection. All parts of the sampling chamber are connected using sealing rubber rings, ensuring the airtightness of the electronic nose experimental environment.

Claims

1. A quantitative sample introduction system for an electronic nose, characterized in that, include: Sample quantitative extraction device, sample injection chamber, heating device and air blowing pump pipeline; The sample quantitative extraction device includes a quantitative extraction pump and an injection needle; Use a quantitative extraction pump, set the range, and use an injection needle with the corresponding range. Set the target volume of liquid to be extracted on the extraction pump so that the target volume of VOC sample can be extracted repeatedly. The sample inlet chamber is a hollow stainless steel device, including an inlet, a slide plate, an observation window, a light source, a KF16 vacuum clamp, and a fixing and mounting device. The sample injection chamber is mechanically connected to the sensor sensing chamber via a KF16 vacuum clamp; the sample injection chamber is connected to the sensor sensing chamber via an air pump pipeline. The injection port is located at the top of the injection chamber; after the VOC sample is extracted, the injection needle is inserted into the injection port. The slide plate is installed between the inlet and the bottom of the injection chamber. The VOC sample flows on the slide plate and leaves traces. The increased surface area accelerates the volatilization process. The observation window is used to observe the situation inside the chamber; the light source is connected to a fixed rod outside the sample injection chamber through a fixed installation device, and the light emitted by the light source enters the sample injection chamber through the observation window; The heating device includes a heating element and a heating controller; the heating element is attached to the bottom of the sample injection chamber, and the heating controller controls the target temperature of the heating element to promote the rapid volatilization of VOC samples in the sample injection chamber.

2. The electronic nose quantitative sample introduction system according to claim 1, characterized in that, The observation window is made of quartz glass and is sealed to a stainless steel ring via inner and outer rubber rings.

3. The quantitative sample introduction system for an electronic nose according to claim 1, characterized in that, The injection port includes a silicone rubber gasket, a nut, and a top rubber ring; the nut presses against the silicone rubber gasket and forms a shrinkage preload, and the top rubber ring further presses against the nut, ensuring the sealing of the injection port.

4. The quantitative sample introduction system for an electronic nose according to claim 1, characterized in that, The air blowing pump pipeline includes an air blowing pump and an air blowing pipeline; the air blowing pump is located in the sensor sensing chamber, one end of the air blowing pipeline is connected to the air blowing pump, and the other end extends into the sample injection chamber; the air blowing pump blows the gas in the sensor sensing chamber into the sample injection chamber through the air blowing pipeline, thereby pressing the gaseous VOC in the sample injection chamber into the sensor sensing chamber. After a certain period of time, the quantitative injection of gaseous VOC in the sample injection chamber into the sensor sensing chamber is achieved; the air blowing pipeline 22 uses a 5*8mm transparent rubber tube with a length of 1 meter.

5. The quantitative sample introduction system for an electronic nose according to claim 1, characterized in that, The injection needle is a small-diameter needle with a side opening and a pointed tip to reduce the size of the puncture site and ensure airtightness.

6. The quantitative sample introduction system for an electronic nose according to claim 1, characterized in that, After the VOC sample is injected into the injection chamber by the injection needle, it is dripped directly onto the slide plate. Under the action of gravity, the VOC sample slides to the bottom, leaving scratches and gradually spreading out.

7. The quantitative sample introduction system for an electronic nose according to claim 1, characterized in that, The air pump is a high-pressure, high-flow type.

8. The quantitative sample introduction system for an electronic nose according to claim 1, characterized in that, The sensor chamber is equipped with a fan to ensure that the gas is evenly distributed within the sensor chamber.

9. A method for quantitative sampling using an electronic nose employing the quantitative sampling system as described in claim 1, characterized in that, The specific steps are as follows: Step 1: Based on the required concentration and the size of the sensor chamber, obtain the required VOC volume; place the injection needle on the quantitative extraction pump, set the corresponding volume on the quantitative extraction pump, insert the injection needle tip into the VOC liquid, and the quantitative extraction pump draws the VOC liquid into the injection needle tube at a uniform speed and quantity, then remove the injection needle from the quantitative extraction pump. Step 2: Insert the injection needle into the injection port, inject the VOC liquid, and then quickly pull it out and cover it with the top rubber ring; wait for the VOC liquid to evaporate on the slide plate. At this time, the VOC liquid becomes VOC gas and exists in the injection chamber. Step 3: Turn on the air pump, wait for the concentrations of VOCs in the sample injection chamber and the sensor sensing chamber to reach equilibrium, then turn off the air pump; Step 4: Turn on the fan inside the sensor chamber, wait 5 minutes, and then turn off the fan; the odor signal detected by the gas sensor inside the sensor chamber will remain stable at this time.

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