Microfluidic technology-based trace formaldehyde detection chip, device and method

Abstract

The invention provides a micro-fluidic technology-based trace formaldehyde detection chip, device and method. In the trace formaldehyde detection chip, the first liquid inlet flow channel is communicated with the plurality of reaction micro-flow channels, so that a reagent is stably introduced and uniformly shunted, and formaldehyde is in full contact with a formaldehyde detection reagent in cooperation with the communication design of the gas flow channel and the reaction micro-flow channels; the multi-thread design of the plurality of reaction micro-channels increases the contact opportunity, overcomes the problem of insufficient reaction, realizes trace level detection precision, accurately controls the reagent dosage, and reduces the cost and waste liquid pressure. Meanwhile, the chip integrates all detection links, tedious steps are not needed, operation is simplified and automatic, labor cost is reduced, external temperature and humidity interference can be reduced through a closed flow channel system, and detection accuracy, low cost and convenience are all considered.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of formaldehyde detection, and more particularly relates to a trace formaldehyde detection chip, device and method. BACKGROUND

[0002] Formaldehyde is a common indoor air pollutant with a pungent odor, which is harmful to human health, and long-term exposure may cause respiratory diseases and even cancer. Therefore, detecting formaldehyde concentration is crucial for indoor air quality and human health. However, the existing formaldehyde detection technology has the problem of being difficult to achieve both low cost and high precision. SUMMARY

[0003] The purpose of the embodiments of the present application is to provide a trace formaldehyde detection chip, device and method based on microfluidic technology to solve the technical problem of being difficult to achieve both low cost and high precision in the prior art.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present application is to provide a trace formaldehyde detection chip based on microfluidic technology, which comprises: A first liquid inlet is arranged on the first liquid inlet for introducing formaldehyde detection reagent; A plurality of reaction microchannels; the plurality of reaction microchannels are in communication with the first liquid inlet, so that the formaldehyde detection reagent is divided into the plurality of reaction microchannels from the first liquid inlet; A gas flow channel; the gas flow channel is provided with a first air inlet and a second air inlet, one of which is used to introduce the gas to be detected, and the other is used to discharge the gas after reaction; the gas flow channel is in communication with the plurality of reaction microchannels, so that the formaldehyde in the gas to be detected and the formaldehyde detection reagent in the plurality of reaction microchannels are in contact and react; A detection channel; the plurality of reaction microchannels are in communication with the detection channel, and a detection instrument is arranged on the detection channel to detect the reaction product of the formaldehyde detection reagent and the formaldehyde.

[0005] Optionally, the connection space is formed at the connection between the gas flow channel and the reaction microchannel, the reaction microchannel is located at the lower part of the connection space, and the gas flow channel is located at the upper part of the connection space.

[0006] Optionally, the trace formaldehyde detection chip comprises a bottom plate and a top plate, a first recess is formed on the bottom plate to form a reaction microchannel, and a second recess is formed on the top plate to form a gas flow channel, and the top plate covers the bottom plate so that the gas flow channel is located above the reaction microchannel.

[0007] Optionally, the plurality of reaction microchannels extend along a first direction, the gas flow channel extends along a second direction, and the first direction intersects the second direction, so that the gas flow channel and the plurality of reaction microchannels are in communication.

[0008] Optionally, the top plate is provided with a first air pipe and a second air pipe on two sides respectively, the first air pipe has a first through hole part and a first closed part, and the second air pipe has a second through hole part and a second closed part; The first through hole part is opposite to the position of the top plate, and the first air port is arranged in the first through hole part; the second through hole part is opposite to the position of the top plate, and the second air port is arranged in the second through hole part. The first closed part and the second closed part are opposite to the position of the bottom plate, so that the bottom plate is positioned between the first closed part and the second closed part on two sides.

[0009] Optionally, the two ends of the gas flow channel are respectively provided with an enlarged cavity, and the gas flow channel is communicated with the first air port and the second air port through the enlarged cavities at the two ends.

[0010] Optionally, the trace formaldehyde detection chip further comprises a second liquid inlet channel, the second liquid inlet channel is provided with a second liquid inlet for introducing a colorant, and the second liquid inlet channel is connected between the reaction micro-channel and the detection channel.

[0011] Optionally, the trace formaldehyde detection chip further comprises a coloration channel, the coloration channel is connected between the second liquid inlet channel and the detection channel, and the coloration channel is arranged in a serpentine shape.

[0012] Optionally, a mixing cavity is arranged between the second liquid inlet channel and the reaction micro-channel, so that the fluid in the plurality of reaction micro-channels is mixed with the colorant in the second liquid inlet channel in the mixing cavity before mixing.

[0013] Optionally, the trace formaldehyde detection chip further comprises an exhaust passage connected above the mixing cavity for exhausting the gas collected in the upper part of the mixing cavity.

[0014] Optionally, the detection instrument comprises an ultraviolet light source and an optical probe, the ultraviolet light source is used for emitting ultraviolet light to the detection channel, and the optical probe is used for receiving the optical signal fed back by the fluid in the detection channel to detect the product after the colorant is colored.

[0015] The application also provides a formaldehyde detection device, which comprises the trace formaldehyde detection chip based on micro-fluidic technology.

[0016] Optionally, the formaldehyde detection device further comprises an air flow circulation driving member and a buffer chamber. One end of the air flow circulation driving member is communicated with the buffer chamber, the other end is communicated with the first air port, and the second air port is communicated with the buffer chamber.

[0017] Optionally, the formaldehyde detection device comprises a bearing member, and the trace formaldehyde detection chip is arranged on the bearing member. The bearing member is provided with a heating mechanism, and the trace formaldehyde detection chip is provided with a temperature measuring element for detecting the temperature of the trace formaldehyde detection chip, and the heating mechanism is configured to heat the trace formaldehyde detection chip based on the temperature measured by the temperature measuring element.

[0018] The application also provides a formaldehyde detection method, which adopts the trace formaldehyde detection chip based on microfluidic technology. The formaldehyde detection reagent is introduced into the first liquid inlet channel, so that the formaldehyde detection reagent enters the plurality of reaction microchannels; The first gas inlet is introduced into the to-be-detected gas, and the second gas inlet is introduced into the reacted gas, so that the formaldehyde in the to-be-detected gas reacts with the formaldehyde detection reagent in the plurality of reaction microchannels, and the reaction product of the formaldehyde detection reagent and the formaldehyde enters the detection channel; The reaction product in the detection channel is detected by a detection instrument to obtain the concentration of formaldehyde in the to-be-detected gas.

[0019] Optionally, after the first gas inlet is introduced into the to-be-detected gas, and the second gas inlet is introduced into the reacted gas, the formaldehyde detection method further comprises: The reacted gas introduced from the second gas inlet is introduced into the buffer chamber; The gas in the buffer chamber is introduced into the first gas inlet as the to-be-detected gas by the air flow circulation driving element.

[0020] Optionally, after the first gas inlet is introduced into the to-be-detected gas, and the second gas inlet is introduced into the reacted gas, the formaldehyde detection method further comprises: The introduction of the to-be-detected gas into the first gas inlet is stopped; The to-be-detected gas is introduced into the second gas inlet, and the reacted gas is introduced from the first gas inlet.

[0021] The trace formaldehyde detection chip based on microfluidic technology, the device and the method provided by the application have the following beneficial effects: compared with the prior art, in the trace formaldehyde detection chip in the embodiment of the application, the first liquid inlet channel is in communication with the plurality of reaction microchannels, which ensures that the reagent is stably introduced and uniformly distributed, and the communication design of the gas channel and the reaction microchannel allows the formaldehyde to fully contact with the formaldehyde detection reagent; the multi-thread design of the plurality of reaction microchannels increases the contact opportunity, overcomes the problem of insufficient reaction, realizes the detection precision of the trace level, accurately controls the amount of reagent, reduces the cost and waste liquid pressure. At the same time, the chip integrates all detection links, without complicated steps, simplifies the operation and can be automated, reduces the labor cost, the closed channel system can also reduce the interference of external temperature and humidity, and the detection accuracy, low cost and convenience are considered. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0023] Figure 1 A schematic diagram of a trace formaldehyde detection chip in the embodiments of the present application; Figure 2 An exploded schematic diagram of a trace formaldehyde detection chip in the embodiments of the present application; Figure 3 A bottom plate schematic diagram of a trace formaldehyde detection chip in the embodiments of the present application; Figure 4 A top plate schematic diagram of a trace formaldehyde detection chip in the embodiments of the present application; Figure 5 An enlarged view of A in FIG. 1; Figure 4 Figure 6 An enlarged view of B in FIG. 1; Figure 4 Figure 7 A schematic diagram of a formaldehyde detection device in the embodiments of the present application; Figure 8 An exploded schematic diagram of a formaldehyde detection device in the embodiments of the present application; Figure 9 A flow schematic diagram of a formaldehyde detection method in the embodiments of the present application.

[0024] In the drawings, each reference numeral represents: a trace formaldehyde detection chip 100; a top plate 10; a bottom plate 20; a first liquid inlet flow channel 11; a first liquid inlet 111; a reaction micro-flow channel 12; a gas flow channel 13; a first air vent 131; a second air vent 132; a first air tube 133; a first through-hole part 1331; a first closed part 1332; a second air tube 134; a second through-hole part 1341; a second closed part 1342; an enlarged cavity 135; a detection flow channel 14; a detection instrument 141; a second liquid inlet flow channel 15; a second liquid inlet 151; a coloring flow channel 16; a mixing cavity 17; an exhaust passage 171; a gas flow circulation driving member 30; a buffer chamber 40; a bearing member 50; a first direction a; a second direction b. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects of the present application more clearly understood, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0026] ​​It is to be noted that when an element is referred to as being "fixed" or "set" on another element, it can be directly on the other element or indirectly on the other element with intervening elements. When an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or indirectly connected or coupled to the other element with intervening elements.

[0027] It is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like, specify relative positions or orientations of an apparatus or element shown in the drawings, and are used only for convenience in describing the present application and simplifying the description, and thus cannot be construed as indicating or implying that a specific orientation is required for the apparatus or element to be in the particular position described and is therefore understood that the application is not limited to the specific orientation described.

[0028] In addition, the terms "first", "second", "third", etc. are used only for descriptive purposes and cannot be construed as indicating or implying relative importance or an indicated number of technical features. Therefore, features defined with "first", "second", etc. can explicitly or implicitly include one or more features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.

[0029] At present, the existing formaldehyde detection technology generally has the characteristics that low cost and high precision are difficult to achieve. Low-cost detection technologies such as sensor technology and desiccator method have high lower limit of detection, and are easily affected by environmental factors such as temperature and humidity, other indoor volatile organic compounds (VOCs), etc. The accuracy and sensitivity of the detection results are insufficient, and the long-term stability is poor. Taking a semiconductor gas sensor as an example, its working principle relies on the conductivity change caused by the adsorption of gas molecules on the surface of metal oxide. However, its response to formaldehyde is not specific, and many volatile organic compounds (VOCs) such as ethanol and toluene can also cause similar signals, resulting in serious cross-interference and extremely poor selectivity. At the same time, its lower limit of detection is usually high (usually above 0.1 mg / m³), which is close to or exceeds the indoor safety standard limit value (0.07-0.08 mg / m³), so it cannot effectively distinguish and quantify trace amounts of formaldehyde within the safety range. Fluctuations in environmental temperature and humidity can also cause significant reading drift, and the long-term stability is insufficient.

[0030] And high-precision detection techniques such as spectroscopy and chromatographic analysis techniques often require complex sample pretreatment procedures, complex detection processes, and expensive precision instruments. For example, the DNPH tube and liquid chromatography method for measuring formaldehyde: by using a sampling tube coated with DNPH (2,4-dinitrophenylhydrazine), a certain volume of air sample is collected by a sampling pump. Formaldehyde in the sample reacts with DNPH under acidic conditions to generate 2,4-dinitrophenylhydrazine derivative. Further extract the derivative from the sampling tube into an organic solvent (acetonitrile or methanol), and obtain the liquid sample by centrifugation, filtration and other operations. Finally, use high performance liquid chromatograph (HPLC) with ultraviolet detector (UVD) or diode array detector (DAD) to separate and detect the derivative. This method requires the use of consumables such as DNPH tubes and expensive precision instruments such as HPLC.

[0031] Although the DNPH tube and liquid chromatography method for measuring formaldehyde can quantitatively detect gaseous formaldehyde concentration, it has the following problems: complex pretreatment steps: it needs to go through sampling tube enrichment, strong acid catalytic derivatization (such as 60°C water bath reaction for 20 minutes), organic solvent extraction (such as cyclohexane or acetonitrile elution) and other steps, the operation process is complicated and time-consuming; high requirement for environmental conditions: the derivatization reaction is sensitive to temperature, humidity and pH value, and needs to be operated in a constant temperature and humidity laboratory. The fluctuation of temperature will cause significant decrease of derivatization efficiency; high equipment and actual cost: the price of high performance liquid chromatograph (HPLC) is usually 500-2000 thousand yuan, and the ultraviolet detector (UV) or diode array detector (DAD) needs to be replaced regularly (about 30 thousand yuan / time). The cost of DNPH reagent and acetonitrile organic solvent is high. If 20 samples are detected per day, the reagent consumption is about 1200 yuan per day; low accuracy of detection results: VOCs such as benzene series and ketones may have competitive reaction with DNPH, resulting in false positive and reducing the accuracy of formaldehyde concentration detection.

[0032] Therefore, it is urgent to develop a formaldehyde detection technology with simple operation process, high sensitivity and accuracy. Based on this, the present application provides a trace formaldehyde detection chip 100, please refer to Figure 1 、 Figure 2 、 Figure 3 and Figure 4 The trace formaldehyde detection chip 100 based on microfluidic technology comprises: A first liquid inlet 111 is arranged on the first liquid inlet 11 for introducing formaldehyde detection reagent; A plurality of reaction microchannels 12 are arranged on the first liquid inlet 11 for introducing formaldehyde detection reagent; Gas flow channel 13; the gas flow channel 13 is provided with a first air port 131 and a second air port 132, one of which is used to introduce the gas to be detected, and the other is used to export the gas after reaction, and the gas flow channel 13 is communicated with a plurality of reaction micro flow channels 12, so that the formaldehyde in the gas to be detected and the formaldehyde detection reagent in the plurality of reaction micro flow channels 12 are contacted and reacted; Detection flow channel 14; a plurality of reaction micro flow channels 12 are communicated with the detection flow channel 14, and a detection instrument 141 is arranged on the detection flow channel 14 to detect the reaction product of the formaldehyde detection reagent and the formaldehyde.

[0033] The first liquid inlet flow channel 11 is provided with a special first liquid inlet 111, and the first liquid inlet 111 is used to introduce the formaldehyde detection reagent. The first liquid inlet flow channel 11 is a special channel for the reagent to enter the chip system, which can ensure that the reagent flows into the subsequent reaction link in a stable and uniform state, lay a foundation for the sufficient reaction of formaldehyde and reagent, and avoid affecting the detection result due to unstable reagent introduction.

[0034] A plurality of reaction micro flow channels 12 are communicated with the first liquid inlet flow channel 11, and the formaldehyde detection reagent flowing from the first liquid inlet flow channel 11 can be uniformly distributed to each of the plurality of reaction micro flow channels 12 through this communication structure. The reaction micro flow channel 12 refers to a micron-level reaction channel, and the plurality of reaction micro flow channels 12 herein are the main place where formaldehyde and detection reagent react, and the multi-channel arrangement can ensure the synchronicity of the reaction and provide structural support for subsequent improvement of detection reliability.

[0035] The gas flow channel 13 is equipped with two air ports, namely the first air port 131 and the second air port 132, and the functions of the two can be flexibly distributed, one is used to introduce the gas to be detected, and the other is used to export the gas after reaction, and there is no fixed gas inlet or gas outlet restriction. The gas flow channel 13 is also communicated with a plurality of reaction micro flow channels 12, and the formaldehyde in the gas to be detected can contact and react with the detection reagent in the plurality of reaction micro flow channels 12 through this communication structure, which creates the necessary conditions for the transfer of formaldehyde from the gas phase to the liquid phase.

[0036] A plurality of reaction micro flow channels 12 are communicated with the detection flow channel 14, and the reaction product generated in each reaction micro flow channel 12 can be collected in the detection flow channel 14 through this communication structure. A detection instrument 141 is specially arranged on the detection flow channel 14, which is used to detect the product generated by the reaction of formaldehyde and detection reagent, and further calculate the concentration of formaldehyde in the gas to be detected through the detection result, to complete the final data output of the entire detection process.

[0037] When the detection chip is in operation, the formaldehyde detection reagent enters the system through the first liquid inlet 111 of the first liquid inlet flow channel 11, and then is evenly distributed into the plurality of reaction micro-flow channels 12. The gas to be detected is introduced from one of the gas inlets of the gas flow channel 13. In the region where the gas flow channel 13 and the plurality of reaction micro-flow channels 12 are in communication, the formaldehyde molecules in the gas fully contact the detection reagent in the plurality of reaction micro-flow channels 12 and undergo specific reactions. After the reaction is completed, the remaining gas is discharged from the other gas inlet, and the generated reaction product is collected in the detection flow channel 14 through the communication structure. Finally, the detection instrument 141 on the detection flow channel 14 detects the product, calculates the concentration of formaldehyde in the gas to be detected according to the detection data, and completes the entire detection process.

[0038] The trace formaldehyde detection chip 100 adopts a multi-thread design of a plurality of reaction micro-flow channels 12. The gas to be detected is distributed into a plurality of independent channels, so that the formaldehyde molecules therein can be contacted and reacted with the detection reagent simultaneously. Compared with a single-channel structure, this design can greatly increase the effective contact opportunity of formaldehyde molecules and reagents, thereby effectively overcoming the problem of insufficient reaction caused by uneven local gas concentration, and ensuring that the reaction is more thorough. This key design provides core support for significantly improving detection accuracy, and finally enables the sensor to stably achieve trace level (i.e., parts per billion level) formaldehyde detection accuracy. At the same time, each reaction micro-flow channel 12 only needs a small amount of reagent to meet the reaction requirement, and the multi-channel distribution design precisely controls the overall reagent consumption, which can significantly reduce the reagent consumption compared with the consumption of a large amount of reagents in the traditional detection method, thereby reducing the cost and the pressure of waste liquid treatment.

[0039] The trace formaldehyde detection chip 100 integrates the reagent introduction, gas contact reaction, and product detection into one whole process, without the need for separate sampling tube enrichment, water bath derivation, centrifugation, filtration, and other cumbersome steps as in the traditional high-precision detection method such as DNPH tube and liquid chromatography. The operation process is greatly simplified, and automation can be realized, thereby reducing labor costs. In addition, the trace reagent consumption characteristics of the plurality of reaction micro-flow channels 12, and the fact that the detection instrument 141 is integrated on the detection flow channel 14 without the need for large and expensive equipment such as a high-performance liquid chromatograph, can significantly reduce the reagent consumption cost and equipment procurement and maintenance cost, thereby achieving obvious comprehensive cost advantage.

[0040] The reagent moves in the closed flow channel system of the first liquid inlet flow channel 11, the plurality of reaction micro-flow channels 12, and the detection flow channel 14, and the gas moves in the gas flow channel 13, which can reduce the influence of external temperature and humidity fluctuations on the reaction, and the external environment changes are difficult to directly interfere with the reaction system in the flow channel.

[0041] In some embodiments of the present application, the connection between the gas flow channel 13 and the reaction micro-flow channel 12 forms a connection space, the reaction micro-flow channel 12 is located at the lower part of the connection space, and the gas flow channel 13 is located at the upper part of the connection space.

[0042] After the to-be-detected gas is introduced from the upper gas flow channel 13, the upper region of the connection space is first filled, at which time the reagent in the plurality of reaction micro-flow channels 12 at the lower part forms a liquid interface at the bottom of the connection space. In the process of full contact between the gas and the liquid interface, the connection space acts as a buffer area, so that the gas does not directly rush into the flow channel, but slowly diffuses in the space, and cooperates with the action of gravity to make the formaldehyde molecules naturally downwardly react with the reagent, which not only prolongs the gas residence time, but also makes the contact more uniform. For trace formaldehyde, longer contact time can reduce the unreacted export caused by too fast flow rate, and more complete reaction directly improves the detection precision; at the same time, the reagent is gathered at the bottom and the liquid surface is stable, and will not splash to the upper region due to gas impact, avoiding invalid loss, and without filling the entire communication region, cooperating with the micro amount requirement of the plurality of reaction micro-flow channels 12, the reagent amount can be more accurately controlled, and the cost is significantly reduced.

[0043] After the reaction is completed, the gas not participating in the reaction is exported from the upper gas flow channel 13, and the product is left in the plurality of reaction micro-flow channels 12 to be collected to the detection flow channel 14, and there is no flow field disorder problem in the entire process. In addition, the transition design of the connection space can also avoid damage to the plurality of reaction micro-flow channels 12 caused by gas pressure impact, and prevent the reagent from backflowing to block the gas flow channel 13.

[0044] Please refer to Figure 2 、 Figure 3 and Figure 4 In some embodiments of the present application, the trace formaldehyde detection chip 100 includes a bottom plate 20 and a top plate 10, the first recess is formed on the bottom plate 20 to form the reaction micro-flow channel 12, and the second recess is formed on the top plate 10 to form the gas flow channel 13, and the top plate 10 covers the bottom plate 20, so that the gas flow channel 13 is located above the reaction micro-flow channel 12.

[0045] The plurality of reaction micro-channels 12 formed by the first grooves of the bottom plate 20 can stably contain the formaldehyde detection reagent, the groove structure can limit the flow range of the reagent, and avoid random diffusion of the reagent; the gas flow channel 13 formed by the second grooves of the top plate 10 is located above, and after the to-be-detected gas is introduced from the gas flow channel 13, a stable gas flow path can be formed in the groove, directly covering the reagent above the plurality of reaction micro-channels 12 below. When the connection space is formed at the connection between the gas flow channel 13 and the plurality of reaction micro-channels 12, the gas flow channel 13 of the top plate 10 can stably introduce the gas into the upper part of the connection space, and the plurality of reaction micro-channels 12 of the bottom plate 20 can stably limit the reagent in the lower part of the connection space. The formaldehyde molecules naturally diffuse downward into the reagent for reaction by gravity without additional structure guiding. In this process, the gas stably flows in the gas flow path, the reagent remains in a fixed range in the groove, and the two are more fully contacted, especially for trace formaldehyde, which can reduce the detection error caused by insufficient contact and improve the detection accuracy.

[0046] The trace formaldehyde detection chip 100 is constructed by combining the bottom plate 20 and the top plate 10, wherein the bottom plate 20 is easy to process and only needs to be provided with the first grooves to easily form the plurality of reaction micro-channels 12 without complex process; the top plate 10 is provided with the second grooves to form the gas flow channel 13, and after the top plate 10 covers the bottom plate 20, the gas flow channel 13 is naturally located above the plurality of reaction micro-channels 12. This split groove design allows the two to be independently formed on their respective substrates without complex grooving on a single substrate, greatly reducing the difficulty of chip manufacturing, and the assembly mode of the top plate 10 and the bottom plate 20 can accurately ensure that the flow channels correspond in position, avoiding the positional deviation problem of traditional integrated processing, and laying a foundation for effective contact between the gas and the reagent.

[0047] The plurality of reaction micro-channels 12 of the bottom plate 20 stably contain the formaldehyde detection reagent by means of the groove structure, and limit the flow range of the reagent to avoid random diffusion; after the to-be-detected gas is introduced into the gas flow channel 13 of the top plate 10, a stable gas flow path can be formed in the groove, directly covering the reagent above. When the connection space is formed at the connection between the two, the gas enters the upper part of the connection space from the gas flow channel 13 of the top plate 10, and the reagent is limited in the lower part, and the formaldehyde molecules naturally diffuse downward for reaction by gravity without additional guiding.

[0048] Please refer to Figure 2 In some embodiments of the present application, the plurality of reaction micro-channels 12 extend along a first direction a, the gas flow channel 13 extends along a second direction b, and the first direction a intersects the second direction b, so that the gas flow channel 13 and the plurality of reaction micro-channels 12 are in communication.

[0049] The plurality of reaction micro-channels 12 of the trace formaldehyde detection chip 100 extend along a first direction a, the gas flow channel 13 extends along a second direction b, and the first direction a intersects the second direction b, so that the gas flow channel 13 can form crosswise communication with the plurality of reaction micro-channels 12. Compared with a single communication point, multiple communication points can greatly increase the contact sites of the gas and the reagent, so that the to-be-detected gas is more evenly distributed into each reaction micro-channel 12, avoiding the problem of insufficient reaction of some reaction micro-channels 12 due to uneven gas distribution. At the same time, the design of intersecting extension does not need to additionally add a complex distribution structure, and efficient communication of the gas flow channel 13 and the plurality of reaction micro-channels 12 can be realized only by direction intersection, simplifying the layout of the flow channel and further reducing the design difficulty of the internal structure of the chip.

[0050] The plurality of reaction micro-channels 12 extending along the first direction a can provide a longer flow and reaction path for the formaldehyde detection reagent, and the reagent can flow smoothly in the extended flow channel, avoiding local accumulation. After the gas flow channel 13 extending along the second direction b intersects the plurality of reaction micro-channels 12, the to-be-detected gas introduced from the gas flow channel 13 will contact the reagent in the reaction micro-channels 12 at each intersection communication point. Since the communication points formed by the intersection of the two directions are distributed along the extension direction of the reaction micro-channels 12, the gas can gradually enter the reaction micro-channels 12 at different positions, rather than rushing in at a certain position, reducing the disturbance of the reagent flow field caused by the gas impact. Especially when the first direction a and the second direction b are perpendicular to each other, the gas flow channel 13 can cross the plurality of reaction micro-channels 12 arranged along the first direction a, forming a crosswise communication structure, so that the gas can contact the reagent in a wider range. For trace formaldehyde, more contact sites and more uniform gas distribution can give each formaldehyde molecule in the reaction micro-channels 12 sufficient opportunity to react with the reagent, further reducing the detection error caused by uneven gas distribution and improving the detection accuracy.

[0051] Please refer to Figure 4 , Figure 5 and Figure 6 In some embodiments of the present application, the first vent pipe 133 and the second vent pipe 134 are arranged on the two sides of the top plate 10, the first vent pipe 133 has a first through hole part 1331 and a first closed part 1332, and the second vent pipe 134 has a second through hole part 1341 and a second closed part 1342. The first through hole part 1331 is opposite to the position of the top plate 10, and the first vent port 131 is arranged in the first through hole part 1331. The second through hole part 1341 is opposite to the position of the top plate 10, and the second vent port 132 is arranged in the second through hole part 1341. The first closed part 1332 and the second closed part 1342 are opposite to the position of the bottom plate 20, so that the bottom plate 20 is positioned between the first closed part 1332 and the second closed part 1342 on the two sides.

[0052] The first through-hole part 1331 is opposite to the top plate 10, and the first air vent 131 is arranged in the first through-hole part 1331. The second through-hole part 1341 is opposite to the top plate 10, and the second air vent 132 is arranged in the second through-hole part 1341. The to-be-detected gas can enter the first air vent 131 through the first through-hole part 1331 of the first air pipe 133, and then flow into the gas flow channel 13 on the top plate 10. After the reaction, the gas is discharged from the second through-hole part 1341 of the second air pipe 134 through the second air vent 132, forming a complete and independent gas channel. Compared with directly opening the air vent at the edge of the top plate 10, the through-hole part of the air pipe can prolong the gas flow path, reduce the risk of gas leakage during the process of being introduced and discharged, and make the air vent more accurate in docking with the gas flow channel 13 on the top plate 10, avoiding the problem of poor gas flow caused by deviation of the opening position.

[0053] The first closed part 1332 of the first air pipe 133 and the second closed part 1342 of the second air pipe 134 are opposite to the position of the bottom plate 20, and the bottom plate 20 is positioned between the two first closed parts 1332 and the second closed part 1342. This design allows the bottom plate 20 to be assembled with the top plate 10 without the need for additional positioning clamps. The lateral movement of the bottom plate 20 is limited by the closed parts of the two air pipes, ensuring that the multiple reaction micro-channels 12 on the bottom plate 20 extending in the first direction a are accurately aligned with the gas flow channel 13 on the top plate 10 extending in the second direction b.

[0054] This air pipe structure can also improve the overall practicability and processing convenience of the trace formaldehyde detection chip 100. On the one hand, the first air pipe 133 and the second air pipe 134 are arranged as independent components on both sides of the top plate 10, which can be mass-produced by standardized molds. The diameters of the first through-hole part 1331 and the second through-hole part 1341 and the sizes of the first closed part 1332 and the second closed part 1342 can be accurately controlled, ensuring the consistency of the adaptability of each set of air pipes to the top plate 10 and the bottom plate 20, reducing assembly errors caused by component differences, and improving the consistency of mass production. On the other hand, the air pipe simultaneously assumes the functions of air ventilation and positioning, eliminating the need for additional positioning structures or air vent interfaces outside the chip, simplifying the overall structural layout of the chip. Especially when integrating the detection instrument 141 later, the presence of the two air pipes can provide a clear interface for the connection of the chip and the external gas path, making it easier for operators to quickly connect the gas path and improving the convenience of detection operations.

[0055] Please refer to Figure 5 and Figure 6 In some embodiments of the present application, the two ends of the gas flow channel 13 are respectively provided with enlarged cavities 135, and the gas flow channel 13 communicates with the first air vent 131 and the second air vent 132 through the enlarged cavities 135 at the two ends.

[0056] The enlarged cavity 135 can allow the to-be-detected gas entering from the first air inlet 131 to be temporarily buffered in the enlarged cavity 135, avoid the gas directly rushing into the narrow gas flow channel 13 to cause the flow rate to suddenly increase and the gas flow to be turbulent, and make the gas flow more smoothly along the gas flow channel 13, and then uniformly reach the communication points with the plurality of reaction micro-channels 12; after the reaction, the gas gathered in the enlarged cavity 135 at the other end of the gas flow channel 13 can also be buffered in the enlarged cavity 135 and then smoothly enter the second air inlet 132 for leading out, thereby reducing the gas flow resistance.

[0057] Please refer to Figure 2 and Figure 3 In some embodiments of the present application, the trace formaldehyde detection chip 100 further comprises a second liquid inlet channel 15, the second liquid inlet channel 15 is provided with a second liquid inlet 151 for introducing a colorant, and the second liquid inlet channel 15 is connected between the reaction micro-channel 12 and the detection channel 14.

[0058] The second liquid inlet channel 15 of the trace formaldehyde detection chip 100 is provided with the second liquid inlet 151, the colorant can be introduced through the second liquid inlet 151, and the second liquid inlet channel 15 is connected between the reaction micro-channel 12 and the detection channel 14. After the colorant enters through the second liquid inlet channel 15, it can be mixed with the product generated by the reaction of formaldehyde in the reaction micro-channel 12. If the product and the colorant have a color developing reaction, the color change can directly reflect whether the reaction occurs, which is convenient for quickly judging whether the gas contains formaldehyde.

[0059] Taking the phenol reagent as the formaldehyde detection reagent and the ferric ammonium sulfate as the colorant as an example, after the formaldehyde in the to-be-detected gas enters the plurality of reaction micro-channels 12, it will react with the phenol reagent, and the amino group in the phenol reagent can combine with the formaldehyde to generate a zine compound. At this time, the ferric ammonium sulfate introduced through the second liquid inlet 151 enters the plurality of reaction micro-channels 12 through the second liquid inlet channel 15, and the trivalent iron ion in the ferric ammonium sulfate will act as an oxidizing agent to have an oxidation-reduction reaction with the zine compound to generate a blue-green indophenol blue substance. The blue-green indophenol blue product in the detection channel 14 can accurately capture the optical signal by the detection instrument 141. For example, the instrument can measure the absorbance of the blue-green substance, and according to the principle that the absorbance is positively correlated with the concentration of the indophenol blue, and the concentration of the indophenol blue is positively correlated with the concentration of the formaldehyde, the concentration of the formaldehyde in the to-be-detected gas can be more accurately converted. Compared with the transparent product that may exist without the colorant, the blue-green signal is easier to identify, which can effectively reduce the detection error caused by the low concentration of formaldehyde and further improve the accuracy of the trace formaldehyde detection.

[0060] Please refer to Figure 2 and Figure 3 The trace formaldehyde detection chip 100 further comprises a coloration channel 16, the coloration channel 16 is connected between the second liquid inlet channel 15 and the detection channel 14, and the coloration channel 16 is arranged in a serpentine shape.

[0061] The coloring flow channel 16 is arranged between the second liquid inlet flow channel 15 and the detection flow channel 14, and the coloring flow channel 16 is arranged in a serpentine shape. The ammonium ferric sulfate colorant introduced through the second liquid inlet flow channel 15 and the reaction product of the formaldehyde and the phenol reagent of the multiple reaction micro flow channels 12 enter the coloring flow channel 16 together. The serpentine structure prolongs the flow path of the mixed fluid in the flow channel, and generates slight turbulence at the turning points, which can break the stratification of the fluid and make the ammonium ferric sulfate and the zwitterionic compound fully contact, ensuring that the ferric ion and the zwitterionic compound fully undergo redox reaction to generate uniform blue-green indophenol blue substance, avoiding the situation of local non-color development or different color development depth caused by uneven mixing, and improving the accuracy of detection visualization.

[0062] The serpentine coloring flow channel 16 can slow down the flow speed of the mixed fluid indophenol blue product and ammonium ferric sulfate, avoiding uneven distribution of the product caused by too fast fluid entering the detection flow channel 14. At the same time, the prolonged flow channel length can make the fluid more stable during flow, reduce the residue of the product on the inner wall of the flow channel caused by flow speed fluctuation, and ensure that more uniformly mixed products can flow smoothly into the detection flow channel 14. After entering the detection flow channel 14, the uniform blue-green product can make the detection instrument 141 capture more stable absorbance signals, and according to the positive correlation between absorbance and indophenol blue concentration formaldehyde concentration, the formaldehyde concentration can be more accurately converted, further reducing the detection error caused by uneven mixing or residue of the product, and improving the reliability of trace formaldehyde detection.

[0063] Please refer to Figure 2 and Figure 3 In some embodiments of the present application, a mixing chamber 17 is arranged between the second liquid inlet flow channel 15 and the reaction micro flow channel 12, so that the fluid of the multiple reaction micro flow channels 12 and the colorant of the second liquid inlet flow channel 15 are mixed in the mixing chamber 17 before mixing.

[0064] The trace formaldehyde detection chip 100 is provided with a mixing chamber 17 downstream of the multiple reaction micro flow channels 12, and the second liquid inlet flow channel 15 is connected downstream of the mixing chamber 17. In the multiple reaction micro flow channels 12, the product generated by the reaction of formaldehyde and detection reagent flows into the mixing chamber 17, and with the help of the containing space of the mixing chamber 17, multiple product streams can fully converge and eliminate the concentration difference of single stream, forming a whole product fluid with uniform composition. This step of pre-mixing can avoid color development deviation caused by uneven local concentration of the product when mixed with the colorant later, laying a stable material foundation for the coloring reaction.

[0065] After the mixed overall product fluid flows out of the mixing chamber 17, it will meet and mix with the colorant introduced by the second liquid inlet channel 15 downstream. This sequence of pre-mixing the product and then mixing the colorant allows the colorant to be uniformly dispersed in the homogenized product fluid, reducing the impact and stratification when the two are directly connected. The uniformly mixed product and colorant can smoothly enter the subsequent serpentine coloration channel 16, relying on the extended path and turbulence at the turns of the coloration channel 16 to further deepen the color development reaction, generating a color-developed product with uniform color, and improving the detection effect.

[0066] Please refer to Figure 2 In some embodiments of the present application, the trace formaldehyde detection chip 100 further comprises an exhaust passage 171 connected above the mixing chamber 17 for exhausting the gas accumulated in the upper part of the mixing chamber 17.

[0067] When the reaction products of formaldehyde and detection reagents in the plurality of reaction microchannels 12 flow into the mixing chamber 17, they may carry a small amount of gas (such as reaction-generated gas or residual air in the channel). These gases tend to accumulate in the upper part of the mixing chamber 17 to form a gas mass. If the gas mass accumulates, it will occupy the internal space of the mixing chamber 17, squeezing the accommodation area of the product fluid, causing multiple product fluids to be unable to fully diffuse and converge, making it difficult to form an overall product fluid with uniform composition, and further affecting the mixing effect with the colorant downstream.

[0068] The exhaust passage 171 can clear the gas mass in the mixing chamber 17 by exhausting the gas in the upper part of the mixing chamber 17, providing sufficient and complete mixing space for the product fluid, allowing multiple product fluids to fully contact and eliminate concentration differences, and ensuring that the overall product fluid after pre-mixing has uniform composition. At the same time, the presence of the gas mass may hinder the flow of the product fluid from the mixing chamber 17 downstream, causing flow rate fluctuations or local retention. After the exhaust passage 171 exhausts the gas, it can reduce the flow resistance of the fluid, allowing the overall product fluid after pre-mixing to flow smoothly into the downstream colorant mixed with the second liquid inlet channel 15, avoiding deviations in the mixing ratio of the colorant caused by unstable flow rate.

[0069] In addition, after the gas in the upper part of the mixing chamber 17 is exhausted, the gas mass can be prevented from entering the subsequent serpentine coloration channel 16 or detection channel 14 with the fluid. If the gas enters the coloration channel 16, it may form bubbles at the turns, interfering with the uniformity of the color development reaction; if it enters the detection channel 14, the bubbles will affect the capture of the color-developed product signal by the detection instrument 141 (such as blocking the optical signal), causing detection errors. The provision of the exhaust passage 171 can reduce such interference, further ensuring the accuracy and reliability of trace formaldehyde detection.

[0070] In some embodiments of the present application, the detection instrument 141 comprises a UV light source for emitting UV light to the detection flow channel 14 and an optical probe for receiving the optical signal fed back by the fluid in the detection flow channel 14 to detect the product after the colorant is colored.

[0071] The UV light source is used to emit UV light to the detection flow channel 14, and when the fluid fully reacts in the serpentine coloration flow channel 16 to form the colored product, the colored product combined with the reaction product of the detection reagent after the formaldehyde is colored and flows into the detection flow channel 14, the UV light can penetrate the colored product. Different concentrations of colored products have different absorption abilities of UV light of a specific wavelength, the higher the concentration of the colored product, the stronger the absorbed UV light, and the weaker the transmitted light, which provides a direct basis for deducing the concentration of formaldehyde through the optical signal. The optical probe is used to receive the optical signal fed back by the fluid in the detection flow channel 14, that is, the UV light signal after penetrating the colored product, which can convert the light signal into an electrical signal, and after data processing, the concentration of the colored product is calculated, and then the specific content of formaldehyde in the gas to be detected is obtained according to the positive correlation between the concentration of the colored product and the concentration of formaldehyde.

[0072] The UV light source can be adjusted to a wavelength band matched with the characteristic absorption wavelength of the colored product, to ensure that only the colored product is detected specifically, to avoid the interference of unreacted detection reagent colorant and other impurities on the optical signal, and to improve the specificity of detection. The high-sensitivity design of the optical probe can capture the weak optical signal fed back by the low-concentration colored product, so that even if the concentration of formaldehyde is very low, the concentration of the colored product can also be accurately identified through the change of the signal, which is suitable for trace formaldehyde detection scenarios, and further guarantees the accuracy and application range of detection.

[0073] Referring to Figure 7 , based on the trace formaldehyde detection chip 100 in the above embodiments, the present application further provides a formaldehyde detection device, which comprises the trace formaldehyde detection chip 100 in any of the above embodiments, and can realize accurate and low-cost detection of formaldehyde.

[0074] Referring to Figure 1 , Figure 7 and Figure 8 , in some embodiments of the present application, the formaldehyde detection device further comprises an air flow circulation driving member 30 and a buffer chamber 40; one end of the air flow circulation driving member 30 communicates with the buffer chamber 40, and the other end communicates with the first air inlet 131; the second air inlet 132 communicates with the buffer chamber 40.

[0075] The air flow circulation driving member 30 is in communication with the buffer chamber 40 at one end and the first air vent 131 at the other end, and the second air vent 132 is in communication with the buffer chamber 40, forming a circulation path of the buffer chamber 40, the first air vent 131, the gas flow channel 13, the second air vent 132, and the buffer chamber 40. The air flow circulation driving member 30 is usually a gas pump or a micro fan, which can provide stable power to push the to-be-detected gas in the buffer chamber 40 to continuously enter the gas flow channel 13 of the trace formaldehyde detection chip 100 through the first air vent 131, so that the gas repeatedly flows through multiple reaction micro flow channels 12 and contacts the detection reagent. The formaldehyde that is not completely reacted in the first contact will return to the buffer chamber 40 with the gas flow, and then re-enter the gas flow channel 13 through circulation to contact the detection reagent again. Through such a cycle of contact process, the formaldehyde in the to-be-detected gas is more completely reacted and absorbed, avoiding the detection omission of low-concentration formaldehyde due to insufficient single-contact reaction, and being especially suitable for the complete reaction of low-concentration formaldehyde.

[0076] The buffer chamber 40 can temporarily store the to-be-detected gas, reduce the flow rate fluctuation when the air flow circulation driving member 30 directly supplies gas, make the gas flow rate entering the first air vent 131 more stable, and then ensure the stability of the gas flow in the gas flow channel 13, avoiding uneven gas distribution caused by sudden flow rate change, such as insufficient gas in some reaction micro flow channels 12. Stable gas flow can make the gas of each cycle uniformly distributed to multiple reaction micro flow channels 12, ensuring that the detection reagent and the gas are in full contact, and further promoting the complete reaction and absorption of formaldehyde. At the same time, the gas that is not completely reacted returns to the buffer chamber 40 through the second air vent 132 and re-enters the trace formaldehyde detection chip 100 for reaction through circulation, which not only improves the gas utilization rate and reduces gas waste, but also improves the formaldehyde conversion efficiency through multiple reactions, makes the concentration of the final reaction product more consistent with the actual formaldehyde content, and the optical signal captured by the detection instrument 141 is more accurate, thereby improving the detection precision and assisting the formaldehyde detection device to realize more accurate trace formaldehyde detection.

[0077] According to the structure design of the above-mentioned formaldehyde detection device, the reaction process and color development process of gas-phase formaldehyde and phenol reagent can be simplified as a one-dimensional convective mass transfer model, and the reaction kinetics process can also be analyzed as a source-sink phase of fluid-side formaldehyde. It is assumed that the fluid in the gas-liquid mixing section is fully mixed, and the control equations of the fluid-side formaldehyde concentration and the zine compound generated by the reaction of the fluid-side formaldehyde and the phenol reagent in the micro flow channel are shown in formulas (1) and (2).

[0078] (1) (2) Wherein, C f (μg / mL), C p (μg / mL), andC t Cf (μg / mL) and Cx (μg / mL) are the concentrations of formaldehyde and xanthene compound on the fluid side, respectively, where C C p may be approximately constant; D w,f cm / s) and 2 cm / s) are the diffusion coefficients of formaldehyde and xanthene compound in aqueous solution, respectively; D w,t cm / s) and 2 cm / s) are the diffusion coefficients of formaldehyde and xanthene compound in aqueous solution, respectively; u 1 (cm / s) is the fluid velocity in the microfluidic channel of the gas-liquid mixing section; k 1 (ml / μg / s) is the reaction rate constant of the reaction between formaldehyde and phenol reagent. After the sample is fully reacted, the xanthene compound will react with the ferric ammonium sulfate color developing reagent in the serpentine-shaped microfluidic channel of the color developing section to form an iron-xanthene complex for detecting the concentration by ultraviolet spectrophotometry. The control equations of the xanthene compound and the iron-xanthene complex in the color developing section are shown in equations (3) and (4).

[0079] (3) (4) wherein, C af Cf (μg / mL) and Cx (μg / mL) are the concentrations of formaldehyde and xanthene compound on the fluid side, respectively, where C C io Cf (μg / mL) and Cx (μg / mL) are the concentrations of formaldehyde and xanthene compound on the fluid side, respectively, where C C af may be approximately constant; D w,io cm / s) is the diffusion coefficient of the iron-xanthene complex in aqueous solution; 2 cm / s) is the diffusion coefficient of the iron-xanthene complex in aqueous solution; u 2 (cm / s) is the fluid velocity in the microfluidic channel of the color developing section; k 2 (ml / μg / s) is the reaction rate constant of the reaction between the xanthene compound and the ferric ammonium sulfate color developing reagent.

[0080] As can be seen from equations (1) to (4), D w , u and k are kinetic parameters that promote the mass transfer and conversion of the fluid side. D w and k are strongly related to temperature. Based on this, in some embodiments of the present application, the formaldehyde detection device comprises a carrier 50, and the trace formaldehyde detection chip 100 is arranged on the carrier 50. The carrier 50 is provided with a heating mechanism, the trace formaldehyde detection chip 100 is provided with a temperature measuring element for detecting the temperature of the trace formaldehyde detection chip 100, and the heating mechanism is configured to heat the trace formaldehyde detection chip 100 based on the temperature measured by the temperature measuring element.

[0081] The temperature measuring element can detect the temperature of the trace formaldehyde detection chip 100 in real time and feed back the temperature information to the heating mechanism. When it is detected that the temperature of the chip is lower than the appropriate temperature required for the reaction of formaldehyde and the detection reagent, the heating mechanism will start and transfer heat to the carrier 50, and the heat will be conducted to the trace formaldehyde detection chip 100 through the carrier 50, so that the temperature of the chip gradually rises to the appropriate range; when the temperature measuring element detects that the temperature of the chip reaches the appropriate value, the heating mechanism will adjust the heating intensity or stop heating to avoid the decomposition of the detection reagent or the reaction product due to too high temperature, and to ensure that the chip is always in a temperature environment conducive to reaction. The heating mechanism can use an electric heating element, which can cooperate with elements such as heat pipes and heat plates to uniformly transfer heat to the trace formaldehyde detection chip 100.

[0082] The appropriate temperature can accelerate the reaction rate of formaldehyde and the detection reagent in the multiple reaction microchannels 12, shorten the time for the reaction to reach a sufficient state, and especially for low concentration formaldehyde, can reduce the problem of long detection time caused by slow reaction. At the same time, a stable temperature environment can avoid the difference in reaction efficiency caused by temperature fluctuations. If the temperature is too low, the reaction may not be sufficient, resulting in a reaction product concentration lower than the actual formaldehyde concentration; if the temperature is too high, it may trigger a side reaction and generate interfering substances affecting the detection result. The heating mechanism based on the temperature feedback of the temperature measuring element can realize precise temperature control, so that the reaction conditions of each detection remain consistent, ensuring that the concentration of the generated reaction product accurately reflects the formaldehyde content in the gas to be detected, and the optical signal captured by the subsequent detection instrument 141 is more reliable, further improving the detection accuracy of the formaldehyde detection device.

[0083] Taking the color development of phenol reagent with ferric ammonium sulfate as an example, the heating mechanism can not be started when the temperature is higher than 23℃, and the heating mechanism can be started when the temperature is lower than 23℃.

[0084] Based on the above trace formaldehyde detection chip 100, please refer to Figure 9 The application also provides a formaldehyde detection method, which comprises: S110, introduce the formaldehyde detection reagent into the first liquid inlet channel 11, so that the formaldehyde detection reagent enters the plurality of reaction micro-channels 12. When the formaldehyde detection reagent is introduced into the first liquid inlet channel 11, the reagent will naturally branch to the plurality of reaction micro-channels 12 along the first liquid inlet channel 11. The plurality of reaction micro-channels 12 of the trace formaldehyde detection chip 100 are branched and communicated with the first liquid inlet channel 11, which can evenly distribute the reagent to each reaction micro-channel 12, avoiding the situation of insufficient or excessive reagent in a single channel. At the same time, if the heating mechanism on the carrier 50 has been started based on the feedback of the temperature measuring element, the plurality of reaction micro-channels 12 will be in a suitable temperature environment, at which time the entering formaldehyde detection reagent can maintain stable activity, preparing for the subsequent reaction with formaldehyde, without the need for additional adjustment of the reagent state, ensuring the smoothness of the operation and the stability of the reaction basis.

[0085] S120, introduce the to-be-detected gas into the first air inlet 131, and introduce the reacted gas from the second air inlet 132, so that the formaldehyde in the to-be-detected gas reacts with the formaldehyde detection reagent in the plurality of reaction micro-channels 12, and the reaction product of the formaldehyde detection reagent and the formaldehyde enters the detection channel 14. After the to-be-detected gas is introduced into the first air inlet 131, the gas enters the plurality of reaction micro-channels 12 through the gas flow channel 13 and contacts the formaldehyde detection reagent introduced previously. The reaction product flows out along the plurality of reaction micro-channels 12 and finally flows into the detection channel 14, without manual intervention in the product transmission, and the communication design of the flow channel can guide the product to flow naturally to the detection channel 14, preparing for the subsequent detection.

[0086] S130, detect the reaction product in the detection channel 14 by the detection instrument 141 to obtain the formaldehyde concentration in the to-be-detected gas. The signal emitting component of the detection instrument 141 emits a specific type of detection signal to the detection channel 14, and the signal receiving component receives the feedback signal after the signal penetrates the reaction product. Different concentrations of reaction products have different absorption or reflection degrees of detection signals, and the detection instrument 141 converts the concentration of reaction products by processing the signal difference, and obtains the formaldehyde concentration in the to-be-detected gas according to the correlation between the concentration of reaction products and the concentration of formaldehyde. Taking ultraviolet light source detection as an example, the detection instrument 141 emits ultraviolet light with a wavelength of 280-320 nm to the detection channel 14. The signal receiving component can be specifically an optical probe, which receives the ultraviolet light signal penetrating the blue-green substance formed by the reaction of the coloring product formaldehyde and the reaction product of the phenol reagent and ferric ammonium sulfate. The instrument calculates the light absorption degree to convert the concentration of the coloring product, and then obtains the concentration of formaldehyde.

[0087] In some embodiments of the present application, after the to-be-detected gas is introduced into the first air inlet 131 and the reacted gas is discharged from the second air inlet 132, the formaldehyde detection method further comprises: introducing the reacted gas discharged from the second air inlet 132 into the buffer chamber 40; and introducing the gas in the buffer chamber 40 into the first air inlet 131 as the to-be-detected gas by the gas flow circulation driving member 30.

[0088] When the reacted gas discharged from the second air inlet 132 is introduced into the buffer chamber 40, the buffer chamber 40 can temporarily store the gas. At this time, the reacted gas discharged may still contain formaldehyde that has not completely reacted with the formaldehyde detection reagent, especially in the case of trace formaldehyde, a single contact may miss some reactions, and the storage function of the buffer chamber 40 can avoid detection errors caused by direct discharge of this part of gas, and at the same time provide a gas source for subsequent circulation.

[0089] When the gas in the buffer chamber 40 is introduced into the first air inlet 131 by the gas flow circulation driving member 30, the gas flow circulation driving member 30 as the core part of the gas flow control assembly can provide stable power to push the gas into the gas flow channel 13 of the trace formaldehyde detection chip 100 again, so that the residual formaldehyde can be in contact with the formaldehyde detection reagent in the plurality of reaction micro-channels 12 again. Compared with a single air flow process, this circulation operation can prolong the contact time of formaldehyde and reagent, so that the formaldehyde that has not been reacted can fully participate in the reaction, improve the efficiency of the conversion of formaldehyde into reaction products, avoid the low concentration of reaction products caused by the residual formaldehyde, and ensure that the concentration of the reaction products in the subsequent detection channel 14 is more consistent with the actual formaldehyde content in the to-be-detected gas. At the same time, the buffer chamber 40 can also play a role in stabilizing the gas flow during the circulation. When the gas flow circulation driving member 30 directly pushes the gas, it is easy to cause flow rate fluctuations. The buffer chamber 40 can buffer the gas flow through the internal space, so that the flow rate of the gas introduced into the first air inlet 131 remains stable, avoiding uneven distribution of the gas in the plurality of reaction micro-channels 12 caused by sudden changes in the flow rate, and ensuring that the contact conditions of formaldehyde and reagent are consistent in each cycle. In addition, this circulation step does not need to add additional to-be-detected gas, but only needs to reuse the existing gas to improve the detection effect, which not only reduces gas waste, but also does not need complex operation, which is consistent with the low-cost and easy-to-operate characteristics of the overall detection method, and further ensures the accuracy and reliability of the trace formaldehyde detection result.

[0090] In some embodiments of the present application, after the to-be-detected gas is introduced into the first air inlet 131 and the reacted gas is discharged from the second air inlet 132, the formaldehyde detection method further comprises: stopping introducing the to-be-detected gas into the first air inlet 131; introducing the to-be-detected gas into the second air inlet 132, and discharging the reacted gas from the first air inlet 131.

[0091] After stopping the introduction of the to-be-tested gas into the first vent 131, the to-be-tested gas is introduced into the second vent 132, and at this time, the gas flows along the path of the second vent 132 gas flow channel 13 multiple reaction micro flow channels 12 first vent 131, which is opposite to the forward gas flow direction of the first vent 131 gas flow channel 13 multiple reaction micro flow channels 12 second vent 132 in step S120. When the gas flows forward, the gas may not be fully contacted with formaldehyde in some areas due to the difference in resistance in the gas flow channel 13 or the slight uneven distribution of reagents in the multiple reaction micro flow channels 12; the reverse ventilation changes the flow path of the gas in the flow channel, so that the gas more evenly covers every reagent in the multiple reaction micro flow channels 12, so that the residual formaldehyde detection reagent fully participates in the reaction, and the unreacted formaldehyde in the to-be-tested gas is contacted with the reagent again, thereby improving the overall reaction conversion rate and avoiding the problem of incomplete and uneven reaction caused by single gas flow direction.

[0092] Table 1. Comparison with typical methods such as phenol reagent spectrophotometry and DNPH-HPLC method

[0093] The trace formaldehyde detection chip based on microfluidic technology of the present application (referred to as microfluidic chip) has the characteristics of high detection precision, short detection time, low consumption of materials, and low cost.

[0094] Specifically, the size of the microfluidic channel is usually tens to hundreds of microns, and its volume is naturally in the order of nanoliters to microliters. Under this scale, the volume of reagents required for driving fluid and chemical reactions decreases geometrically. Therefore, the single sample reagent amount can be as low as 0.4 μL, and the cost will be reduced accordingly. In the micron-scale channel, the fluid is mainly in laminar flow, and the mass transfer mainly relies on diffusion, and the distance is extremely short. This enables formaldehyde and reagents to be fully and uniformly mixed and reacted in a very short time, and the reaction efficiency is much higher than that in a macroscopic test tube relying on slow diffusion and stirring, which can greatly shorten the sampling and determination time. High efficiency of the reaction means that more to-be-tested substances are converted into detectable signal molecules. The small amount of sample reagent (which can be as low as 0.4 μL) means that the reaction products are highly concentrated in a very small space. When optical detection is performed, although the optical path may be short, the product concentration in the detection area is extremely high, thereby producing a strong detection signal. In addition, the implementation of reaction and detection in the microfluidic chip can reduce external interference and thus reduce background noise. Therefore, the microfluidic chip of the embodiments of the present application has the characteristics of high detection precision, short detection time, and low consumption of materials.

[0095] The traditional microfluidic technology has some defects, mainly in two aspects, one is that the signal strength captured by the detection instrument is usually proportional to the number of substances involved in the reaction, and the small amount of formaldehyde detection reagent and sample means that the absolute number of reaction products produced is relatively small, resulting in a relatively weak detection signal; the second is that at the microscale, the influence of pollutants is significantly amplified, thereby introducing significant random errors. To this end, the embodiments of the present application use multiple reaction microchannels 12, so that the formaldehyde brought by the formaldehyde detection reagent and the gas flow channel 13 of the multiple reaction microchannels 12 is contacted and independently reacted, and finally converged to the detection flow channel 14 for detection. On the one hand, the final detection instrument detects the reaction products converged by multiple reaction microchannels, which can greatly improve the total amount of the detected reaction products, thereby improving the signal strength of the detection while maintaining appropriate microfluidic reactions; on the other hand, since the embodiments of the present application use multiple reaction microchannels 12, even if a certain reaction microchannel 12 is contaminated, it will cause abnormal detection, and when it is converged with other reaction microchannels 12, it will greatly weaken the detection result deviation caused by pollution. In addition, the detection gas is sequentially introduced into multiple reaction microchannels 12, especially in cooperation with the detection gas circulation introduction mode, which can ensure that the formaldehyde in the detection gas can more thoroughly participate in the reaction, thereby effectively improving the detection precision and accuracy.

[0096] Finally, because the microfluidic chip uses multiple reaction microchannels 12 to participate in the absorption and reaction of formaldehyde at the same time, the reaction time can be greatly shortened, the detection gas can be continuously introduced into the gas flow channel 13, reacted with the formaldehyde detection reagent in each reaction microchannel 12, and the formaldehyde detection reagent can also be continuously supplemented into each reaction microchannel 12, so that continuous flow detection and online detection of formaldehyde can be achieved.

[0097] The above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A microfluidic technology-based trace formaldehyde detection chip, characterized in that, The trace formaldehyde detection chip based on microfluidic technology comprises: a first liquid inlet channel, which is provided with a first liquid inlet for introducing a formaldehyde detection reagent; a plurality of reaction micro-channels, each of which is in communication with the first liquid inlet channel, so as to cause the formaldehyde detection reagent to be shunted from the first liquid inlet channel to the plurality of reaction micro-channels; a gas flow channel, which is provided with a first gas inlet and a second gas inlet, one of which is used to introduce a gas to be detected, and the other of which is used to discharge the gas after reaction, and which is in communication with the plurality of reaction micro-channels, so as to cause the formaldehyde in the gas to be detected to contact and react with the formaldehyde detection reagent in the plurality of reaction micro-channels; a detection channel, which is in communication with the plurality of reaction micro-channels, and is provided with a detection instrument, so as to detect the reaction product of the formaldehyde detection reagent and formaldehyde.

2. The microfluidic technology-based trace formaldehyde detection chip according to claim 1, wherein, The connection between the gas flow channel and the reaction micro-channels forms a connection space, the reaction micro-channels are located in the lower part of the connection space, and the gas flow channel is located in the upper part of the connection space.

3. The microfluidic-based trace formaldehyde detection chip according to claim 2, wherein, The trace formaldehyde detection chip comprises a bottom plate and a top plate, the bottom plate is provided with a first recess to form the reaction micro-channels, and the top plate is provided with a second recess to form the gas flow channel, and the top plate covers the bottom plate, so that the gas flow channel is located above the reaction micro-channels.

4. The microfluidic-based trace formaldehyde detection chip according to claim 3, wherein, The plurality of reaction micro-channels extend along a first direction, the gas flow channel extends along a second direction, and the first direction intersects the second direction, so that the gas flow channel and the plurality of reaction micro-channels are in communication.

5. The microfluidic-based trace formaldehyde detection chip according to claim 4, wherein, The top plate is provided with a first gas tube and a second gas tube on both sides, the first gas tube has a first through-hole part and a first closed part, and the second gas tube has a second through-hole part and a second closed part; The first through-hole part is opposite to the top plate, and the first gas inlet is arranged in the first through-hole part, the second through-hole part is opposite to the top plate, and the second gas inlet is arranged in the second through-hole part; The first closed part and the second closed part are opposite to the bottom plate, so that the bottom plate is located between the first closed part and the second closed part on both sides.

6. The microfluidic-based trace formaldehyde detection chip according to claim 5, wherein, The gas flow channel is provided with an enlarged cavity at both ends, and the gas flow channel is in communication with the first gas inlet and the second gas inlet through the enlarged cavities at both ends.

7. The microfluidic-based trace formaldehyde detection chip according to any one of claims 1-6, wherein, The trace formaldehyde detection chip further comprises a second liquid inlet channel, which is provided with a second liquid inlet for introducing a colorant, and is connected between the reaction micro-channels and the detection channel.

8. The microfluidic-based trace formaldehyde detection chip according to claim 7, wherein, The trace formaldehyde detection chip further comprises a coloration channel, which is connected between the second liquid inlet channel and the detection channel, and is arranged in a serpentine shape.

9. The microfluidic-based trace formaldehyde detection chip according to claim 7, wherein, A mixing cavity is arranged between the second liquid inlet channel and the reaction micro-channels, so that the fluid in the plurality of reaction micro-channels is mixed with the colorant in the second liquid inlet channel in the mixing cavity before mixing.

10. The microfluidic-based trace formaldehyde detection chip according to claim 9, wherein, The trace formaldehyde detection chip further comprises an exhaust channel connected to the top of the mixing cavity for exhausting the gas collected in the upper part of the mixing cavity.

11. The microfluidic-based trace formaldehyde detection chip according to claim 7, wherein, The detection instrument comprises an ultraviolet light source for emitting ultraviolet light to the detection flow channel and an optical probe for receiving the optical signal fed back by the fluid in the detection flow channel to detect the product after the colorant is colored.

12. A formaldehyde detection device, characterized by, The formaldehyde detection device comprises the trace formaldehyde detection chip based on microfluidic technology according to any one of claims 1-11.

13. The formaldehyde detection device of claim 12, wherein, The formaldehyde detection device further comprises an air flow circulation driving member and a buffer chamber. One end of the air flow circulation driving member is in communication with the buffer chamber, and the other end is in communication with the first air inlet, and the second air inlet is in communication with the buffer chamber.

14. The formaldehyde detection device of claim 13, wherein, The formaldehyde detection device comprises a carrier, and the trace formaldehyde detection chip is arranged on the carrier. The carrier is provided with a heating mechanism, the trace formaldehyde detection chip is provided with a temperature measuring element for detecting the temperature of the trace formaldehyde detection chip, and the heating mechanism is configured to heat the trace formaldehyde detection chip based on the temperature measured by the temperature measuring element.

15. A method of detecting formaldehyde, characterized by, The formaldehyde detection method adopts the trace formaldehyde detection chip based on microfluidic technology according to any one of claims 1-11, and the formaldehyde detection method comprises: The formaldehyde detection reagent is introduced into the first liquid inlet flow channel, so that the formaldehyde detection reagent enters the plurality of reaction micro flow channels; The formaldehyde detection reagent and the formaldehyde in the reaction product enter the detection flow channel; The reaction product in the detection flow channel is detected by the detection instrument to obtain the concentration of formaldehyde in the detected gas.

16. The formaldehyde detection method according to claim 15, wherein, After the detected gas is introduced into the first air inlet and the reacted gas is discharged from the second air inlet, the formaldehyde detection method further comprises: The reacted gas discharged from the second air inlet is introduced into the buffer chamber; The air flow circulation driving member is used to introduce the gas in the buffer chamber as the detected gas into the first air inlet again.

17. The formaldehyde detection method according to claim 15, wherein, After the detected gas is introduced into the first air inlet and the reacted gas is discharged from the second air inlet, the formaldehyde detection method further comprises: Stop introducing the detected gas into the first air inlet; The detected gas is introduced into the second air inlet, and the reacted gas is discharged from the first air inlet.

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