A microfluidic chip

Abstract

The application discloses a micro-fluidic chip, comprising: a sample injection module, which injects a sample to be mixed into a micro-reservoir mixing module in a controllable injection amount through an external circuit driving a syringe pump; the micro-reservoir mixing module is used for fully mixing a sample containing selenium after digestion, thiocyanate, hydrochloric acid fluid, carrier gas and carrier fluid, and then the mixture enters a thiocyanate online pre-reduction module; the thiocyanate online pre-reduction module generates hydrogen selenide gas through heating reaction and refrigeration reduction reaction and enters a micro-gas-liquid separation chip; a semiconductor refrigeration module is arranged below the thiocyanate online pre-reduction module and is used for real-time control of the temperature of semiconductor refrigeration pieces, so that the heating reaction and the refrigeration reduction reaction are realized; and a collection module is used for collecting the obtained hydrogen selenide gas. The sample is mixed through the micro-reservoir mixing module, and then the heating reaction and the refrigeration reduction reaction are carried out in a reaction area of the thiocyanate online pre-reduction module to generate hydrogen selenide gas, so that the synthesis and reduction time of selenium elements is shortened.

Description

Technical Field

[0001] The invention relates to the technical field of microfluidic chips, in particular to a microfluidic chip containing a micro liquid storage mixing module and a thiourea online pre-reduction module. Background Art

[0002] Microfluidics, based on the microfabrication technology of microelectromechanical systems (MEMS), integrates basic operational units such as sample preparation, reaction, separation, and detection in biological, chemical, and medical analysis processes onto a micron-scale chip, capable of automatically completing the entire analysis process. Micromixing, as a core technology in microfluidics, has become a key technology for the determination and reaction synthesis of trace elements. It uses microchannels and microcolumn obstacles to precisely control the reaction synthesis of fluids in micron- to nanometer-scale spaces, thereby achieving efficient and accurate determination of trace element content.

[0003] In recent years, research on online coupled technologies for microfluidic chips has focused on the use of micromixing devices for efficient micromixing to enable subsequent reaction detection. Rapid determination methods for trace elements (such as selenium) primarily include electrochemical methods, electron activation methods, fluorescence spectrophotometry, inductively coupled plasma mass spectrometry, and atomic spectroscopy. For example, rapid determination of selenium often uses glass beakers as containers. After adding the digested selenium-containing sample, HCl, and thiourea to the first glass beaker, a semiconductor electronic cooler at the bottom of the beaker is used to perform a mixing reaction. The mixed sample is then transferred to a second beaker, where Ar and KBH4 are added and then pre-reduced using an ultrasonic mixer to generate hydrogen selenide gas. The hydrogen selenide gas, after micromixing, enters a gas-liquid separator for selenium determination. The above-mentioned selenium determination method has the problems of severe interference in the measured values, cumbersome operation and high cost. This is because when performing the mixed reaction reduction, two glass beakers are required for the experiment, and a semiconductor electronic refrigerator and an ultrasonic mixer are used as assistance, which increases the cost and difficulty of operation. The sample after the mixed reaction needs to be transferred in an auxiliary container. There is interference during the transfer process, which interferes with the accuracy of the measured value. The morphology of the sample also increases the difficulty of transfer.

[0004] Based on the above problems, microfluidic technology is used as the basis. In-depth research on online coupling technology on micro-mixing chips is of great significance for the application of efficient trace element determination in the fields of biology and chemical analysis. A key factor in realizing the rapid detection of trace elements (such as selenium) by integrating microfluidic chip-atomic fluorescence online coupling is how to effectively realize sample micro-mixing and micro-reaction, which is directly related to whether the subsequent trace elements can be efficiently detected. If the sample is not thoroughly mixed, the subsequent reaction will be insufficient to obtain the required sample or the amount of sample obtained is insufficient, and the reduction reaction to generate hydrogen selenide gas cannot be carried out. Summary of the Invention

[0005] In view of the defects in the prior art, the present invention provides a microfluidic chip to solve the technical problems existing in the prior art.

[0006] The present invention provides a microfluidic chip, comprising: a sampling module, a micro liquid storage and mixing module, a thiourea online pre-reduction module, a semiconductor refrigeration module and a collection module.

[0007] The injection module drives the syringe pump through an external circuit to inject the sample to be mixed into the micro-liquid storage mixing module with a controllable injection volume;

[0008] The micro-liquid storage and mixing module is used to fully micro-mix the digested selenium-containing sample, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid before entering the thiourea online pre-reduction module;

[0009] The thiourea online pre-reduction module uses heating reaction and cooling reduction reaction to generate hydrogen selenide gas which enters the micro gas-liquid separation chip;

[0010] The semiconductor refrigeration module is arranged below the thiourea online pre-reduction module and is used to control the temperature of the semiconductor refrigeration chip in real time to achieve heating reaction and cooling reduction reaction;

[0011] The collection module is used to collect the obtained hydrogen selenide gas.

[0012] Optionally, the injection module includes a syringe pump, an injection tube, an electric liquid valve and a first electric gas valve;

[0013] The injection pump is used to inject the digested selenium-containing sample, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid into the injection tube;

[0014] The sample injection tube is used to input the digested selenium-containing sample, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid into the micro-liquid storage mixing module;

[0015] The electric liquid valve is used to control the injection volume of the digested selenium-containing sample, thiourea, and hydrochloric acid fluid into the micro-liquid storage and mixing module;

[0016] The first electric gas valve is used to control the injection amount of the carrier gas to be reacted into the micro liquid storage and mixing module;

[0017] One end of the sampling tube is connected to the micro liquid storage mixing module, the other end of the sampling tube is connected to the injection pump, and the electric liquid valve and the first electric air valve are respectively installed on the sampling tube.

[0018] Optionally, the micro-liquid storage and mixing module is provided with a glass base layer, a PDMS bottom layer and a micro-liquid storage and mixing layer in sequence from bottom to top, and the micro-liquid storage and mixing layer includes a connected inverted triangle mixing cavity layer and an S-shaped mixing channel layer;

[0019] The inverted triangle mixing chamber layer is used for preliminary micro-mixing of the digested selenium-containing sample, thiourea, and hydrochloric acid fluid;

[0020] The S-shaped mixing channel layer is used for fully micro-mixing the digested selenium-containing sample, thiourea, and hydrochloric acid fluid after preliminary micro-mixing.

[0021] Optionally, the inverted triangular mixing chamber layer includes a plurality of circular inlets, an inverted triangular mixing chamber and a first obstacle array;

[0022] The circular inlet is connected to the inverted triangular mixing chamber through a guide tube. The first obstacle array is located in the inverted triangular mixing chamber. The first obstacle is 6 elliptical obstacles, which are arranged in an inverted triangular array. The number of elliptical obstacles arranged from top to bottom is 3, 2, and 1. The size of each elliptical obstacle is the same, and the spacing between each elliptical obstacle is the same.

[0023] Optionally, a second obstacle is arranged under the S-shaped channel of the S-shaped mixing channel layer. The second obstacle is 21 square obstacles, each square obstacle has a different size, and the square obstacles are arranged horizontally, with a total of three rows, and 7 square obstacles in each row. The spacing between the first and third rows of square obstacles increases from left to right, and the spacing between the second row of square obstacles increases from right to left.

[0024] Optionally, the thiourea online pre-reduction module includes a glass substrate layer, a PDMS bottom layer and a pre-reduction unit layer arranged in sequence from top to bottom, and the pre-reduction unit layer includes an S-shaped heating reaction zone layer and an S-shaped reduction refrigeration zone layer connected to each other;

[0025] The S-shaped heating reaction zone layer fully mixes the digested selenium-containing sample, thiourea and hydrochloric acid fluid and then heats and reacts with CH4N2S to generate selenium;

[0026] The S-type reduction refrigeration zone layer is used to perform a refrigeration reduction reaction on selenium and KBH4 to obtain hydrogen selenide.

[0027] Optionally, the semiconductor refrigeration module includes a control unit, a detection circuit and a semiconductor refrigeration chip;

[0028] The control unit is used to generate a control signal for controlling the temperature of the semiconductor refrigeration chip, and the control signal includes a heating signal and a cooling signal;

[0029] The detection circuit is used to collect the temperature of the semiconductor refrigeration chip in real time;

[0030] The semiconductor refrigeration plate provides corresponding temperature for the thiourea online pre-reduction module to perform heating reaction and cooling reduction reaction according to the control signal of the control unit.

[0031] Optionally, when the control signal is a heating signal, one end of the semiconductor refrigeration plate is a cooling end and the other end is a heat dissipation end, and the heat dissipation end is set below the S-shaped heating reaction zone layer; when the control signal is a cooling signal, one end of the semiconductor refrigeration plate is a cooling end and the other end is a cooling end, and one of the cooling ends is set below the S-shaped reduction cooling zone layer.

[0032] Optionally, the control unit includes an infrared processing controller, a temperature intelligent controller, a temperature data acquisition controller, a PWM controller and a temperature control circuit, and the detection circuit includes a temperature acquisition circuit, an ADC circuit and an infrared receiving circuit;

[0033] The infrared receiving circuit is used to receive the infrared signal sent by the infrared remote controller, identify the infrared signal and convert it into an electrical signal, and transmit the electrical signal to the infrared processing controller;

[0034] The infrared processing controller is used to identify the electrical signal to obtain the corresponding temperature parameters set by the remote control, and send the temperature parameters to the temperature intelligent controller;

[0035] The temperature acquisition circuit is used to collect the temperature signal of the semiconductor refrigeration chip, and transmits the temperature signal to the ADC circuit for analog-to-digital conversion to obtain a digital signal, and transmits the digital signal to the temperature data acquisition controller;

[0036] The temperature data acquisition controller processes the digital signal to obtain the current temperature data of the semiconductor refrigeration chip and forwards it to the temperature intelligent controller;

[0037] The temperature intelligent controller performs intelligent temperature control analysis based on the received temperature data and temperature parameters to obtain a temperature control signal, and sends the temperature control signal to the PWM controller;

[0038] The PWM controller generates a PWM waveform according to the temperature control signal and sends the PWM waveform to the temperature control circuit;

[0039] The temperature control circuit controls the power-on time of the semiconductor refrigeration chip according to the PWM waveform;

[0040] The semiconductor refrigeration chip is used to provide corresponding temperatures for the thiourea online pre-reduction module to perform heating reaction and cooling reduction reaction under the control of the temperature control circuit.

[0041] Optionally, the collection module includes a discharge pipe and a second electric valve, one end of the discharge pipe is connected to the outlet of the thiourea online pre-reduction module, the other end of the discharge pipe is connected to the micro gas-liquid separation chip, and the second electric valve is installed on the discharge pipe.

[0042] The discharge pipe is used to input the hydrogen selenide generated by reduction into the micro gas-liquid separation chip;

[0043] The second electric gas valve is used to control the injection amount of hydrogen selenide gas into the micro liquid storage mixing module.

[0044] Beneficial effects of the present invention:

[0045] A microfluidic chip provided by an embodiment of the present invention has an injection module for injecting and pressurizing reaction liquid and carrier gas. After the reaction liquid enters the micro-liquid storage mixing module, it is mixed in the mixing channel. After pressurization, the mixed liquid enters the reaction zone of the thiourea online pre-reduction module, achieves efficient heat transfer under the heating action of the semiconductor refrigeration module, and completes the synthesis reaction in the reaction channel. After the reaction is completed, it enters the reduction refrigeration zone, achieves efficient pre-reduction under the refrigeration action of the semiconductor refrigeration module, obtains the measured selenium element after the reduction is completed, and discharges the material through the discharge pipe. The technical solution provided by the embodiment of the present invention adopts an inverted triangular mixing chamber with a built-in obstacle to connect the mixing channel with an S-shaped structure and the pre-reduction channel with an S-shaped structure, which can achieve efficient mixing of the reaction liquid and the carrier gas, ensure the homogenization of the system, and use semiconductor heating and semiconductor refrigeration to improve the heat transfer and refrigeration effects, shortening the synthesis reduction time of the selenium element. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0047] Figure 1 A structural block diagram of a microfluidic chip provided by an embodiment of the present invention is shown;

[0048] Figure 2 A schematic structural diagram of a microfluidic chip provided by an embodiment of the present invention is shown;

[0049] Figure 3 Shows a schematic structural diagram of the injection module;

[0050] Figure 4 shows a schematic structural diagram of a micro-liquid storage and mixing module;

[0051] Figure 5 shows a simulated concentration cloud diagram of mixing performed by a micro-liquid storage mixing module;

[0052] Figure 6 Shows a schematic structural diagram of a thiourea online pre-reduction module;

[0053] Figure 7 The figure shows a schematic structural diagram of a semiconductor refrigeration module. DETAILED DESCRIPTION

[0054] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0055] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0056] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used in the specification and appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0057] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0058] As used in this specification and the appended claims, the term "if" can be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "upon determination" or "in response to determining" or "upon detection of [described condition or event]" or "in response to detecting [described condition or event]," depending on the context.

[0059] like Figure 1 As shown, a schematic diagram of the structure of a microfluidic chip is shown, which includes a sampling module, a micro-liquid storage mixing module, a thiourea (TU) online pre-reduction module, a semiconductor refrigeration module and a collection module. The sampling module drives the injection pump through an external circuit to inject the sample to be mixed into the micro-liquid storage mixing unit with a controllable injection amount. The micro-liquid storage mixing module is used to fully micro-mix the sample containing selenium after digestion, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid, and then enter the thiourea online pre-reduction module. The thiourea online pre-reduction module uses heating reaction and cooling reduction reaction to generate hydrogen selenide gas and enter the micro-gas-liquid separation chip. The semiconductor refrigeration module is arranged below the thiourea online pre-reduction module for real-time control of the temperature of the semiconductor refrigeration chip to realize heating reaction and cooling reduction reaction. The collection module is used to collect the obtained hydrogen selenide gas.

[0060] Depend on Figure 2 It can be seen that the micro-liquid storage mixing module sampling areas 1-5 are respectively connected to the injection pumps in the sampling module, the sampling area 1 is the inlet of the sample containing Se(VI) after digestion, the sampling area is the inlet of 2 thiourea (TU), the sampling area 3 is the inlet of HCL fluid, the sampling area 4 is the inlet of carrier fluid 1, the sampling area 5 is the inlet of the standby carrier fluid, the sampling area 6 is the inlet of Ar carrier gas, the sampling area 6 is connected to the carrier gas bottle in the sampling module, the inverted triangle mixing chamber layer 7 of the micro-liquid storage mixing module is connected to the S-shaped mixing channel layer 8, the S-shaped mixing channel layer is connected to the thiourea (TU) online pre-reduction module heating reaction zone 9, the thiourea (TU) online pre-reduction module heating reaction zone 9 is connected to the reduction refrigeration zone 10 of the thiourea (TU) online pre-reduction module, a semiconductor heating plate 11 is set in the heating reaction zone 9, a semiconductor refrigeration plate 12 is set in the reduction refrigeration zone 10, and the thiourea (TU) online pre-reduction module reduction refrigeration zone 10 is connected to the discharge port 13.

[0061] like Figure 3As shown, the sample injection module includes a syringe pump, a sample injection tube, an electric liquid valve and a first electric air valve. The syringe pump is used to inject the digested sample containing selenium, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid into the sample injection tube. The sample injection tube is used to input the digested sample containing selenium, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid into the micro-reservoir mixing module. The electric liquid valve is used to control the injection amount of the digested sample containing selenium, thiourea, hydrochloric acid fluid into the micro-reservoir mixing module. The first electric air valve is used to control the injection amount of the carrier gas to be reacted into the micro-reservoir mixing module. One end of the sample injection tube is connected to the micro-reservoir mixing module, and the other end of the sample injection tube is connected to the syringe pump. The electric liquid valve and the first electric air valve are respectively installed on the sample injection tube. The sample injection module drives the syringe pump to inject the digested sample containing Se(VI), TU, HCL, Ar carrier gas and carrier fluid at the same time, and at the same time, the electric liquid valve and the electric air valve on the sample injection tube are opened, so that the sample enters the micro-reservoir mixing module under controlled amount, realizing the injection of the sample.

[0062] As shown in Figure 4 The micro-reservoir mixing module is sequentially provided with a glass substrate layer, a PDMS (polydimethylsiloxane) bottom layer and a micro-reservoir mixing layer from bottom to top. The micro-reservoir mixing layer includes a reverse triangular mixing cavity layer and an S-shaped mixing channel layer in communication. The reverse triangular mixing cavity layer is used for preliminary micro-mixing of the digested sample containing selenium, thiourea and hydrochloric acid fluid. The S-shaped mixing channel layer is used for sufficient micro-mixing of the digested sample containing selenium, thiourea and hydrochloric acid fluid after preliminary micro-mixing. Figure 5 As shown in

[0063] The reverse triangular mixing cavity layer includes a plurality of circular inlets, a reverse triangular mixing cavity and a first obstacle array. In this embodiment, five circular inlets are used. The circular inlets are connected to the reverse triangular mixing cavity through flow guide pipes. The first obstacle array is located in the reverse triangular mixing cavity. The first obstacle is six elliptical obstacles arranged in a reverse triangular array. The number of elliptical obstacles arranged from top to bottom is 3, 2 and 1 respectively. The size of each elliptical obstacle is the same, and the spacing between each elliptical obstacle is the same. The height of the reverse triangular mixing cavity is 2000 um. The size of the elliptical obstacle in the reverse triangular mixing cavity is short axis length = 300 um and long axis length = 400 um. The spacing between the elliptical obstacles is 800 um.

[0064] The S-shaped mixing channel layer has a second obstacle below the S-shaped channel. The second obstacle consists of 21 square obstacles, each of varying sizes. The obstacles are arranged horizontally in three rows, each containing seven square obstacles. The spacing between the first and third rows increases from left to right, while the spacing between the second row increases from right to left. The width of the channel below the S-shaped mixing channel containing square obstacles is 1400 μm, while the width of the channel above it without obstacles is 1000 μm. The square obstacles in the S-shaped rotating mixing channel range in size from 10 μm to 60 μm in length and 1400 μm in width. The spacing between the obstacles is 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, and 100 μm from left to right in the first and third rows, and 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, and 100 μm from right to left in the second row.

[0065] The channel height embedded in the micro-liquid storage mixing module is 300um. The blocking effect is achieved by the built-in elliptical obstacle with a height of 300um, thereby achieving effective mixing of the sample. When HSeO4 and HCL pass through the inverted triangle mixing chamber, the flow path of the fluid will change due to the obstruction of the elliptical obstacle. The originally parallel or laminar fluid will be diverted before and after the obstacle. The diversion effect allows different fluids to mix on a smaller spatial scale. When the fluid bypasses the obstacle, the fluid merges again. Due to the difference in flow rate and flow direction, the fluid will generate shear force and vortex in the confluence area. It can greatly increase the contact area between fluids, breaking the original laminar structure and allowing different fluid molecules to collide and initially mix in a shorter time. After the sample after initial micro-mixing flows into the S-shaped mixing channel, the different spacings between square obstacles with a height of 300um will form a capillary effect. Due to the combined effects of the viscosity between the liquid and the wall and the surface tension of the liquid, different fluids will spontaneously absorb after passing through the obstacle spacing. The flow path of the fluid has changed, increasing the contact opportunities of different fluids, thereby achieving sufficient micro-mixing of the sample to produce H2SeO4 containing selenium.

[0066] like Figure 6 As shown, the thiourea online pre-reduction module includes a glass substrate layer, a PDMS bottom layer and a pre-reduction unit layer arranged in sequence from top to bottom. The pre-reduction unit layer includes an S-shaped heating reaction zone layer and an S-shaped reduction refrigeration zone layer connected to each other. The S-shaped heating reaction zone layer fully micro-mixes the digested selenium-containing sample, thiourea and hydrochloric acid fluid and then heats and reacts with CH4N2S to generate selenium. The S-shaped reduction refrigeration zone layer is used to perform a refrigeration reduction reaction on selenium and KBH4 to obtain hydrogen selenide.

[0067] The thiourea (TU) online pre-reduction module uses semiconductor heating and cooling to achieve the reaction and reduction of selenium. H2SeO4 containing selenium flows into the S-shaped heating reaction zone. At this time, H2SeO4 reacts with CH4N2S under the heating of the semiconductor wafer to produce hexavalent Se. After the hexavalent Se flows into the S-shaped reduction cooling zone, under cooling conditions, the hexavalent Se reacts with KBH4 to reduce and generate H2Se containing tetravalent selenium.

[0068] like Figure 7 As shown, the semiconductor refrigeration module includes a control unit, a detection circuit and a semiconductor refrigeration plate. The control unit is used to generate a control signal for controlling the temperature of the semiconductor refrigeration plate. The control signal includes a heating signal and a cooling signal. The detection circuit is used to collect the temperature of the semiconductor refrigeration plate in real time. The semiconductor refrigeration plate provides the corresponding temperature for the thiourea online pre-reduction module to perform heating reaction and cooling reduction reaction according to the control signal of the control unit.

[0069] The semiconductor refrigeration module realizes visual and intelligent heating and cooling of the thiourea (TU) online pre-reduction module through a control unit and a detection circuit, thereby realizing the conversion of high-valent selenium elements to low-valent selenium elements. Among them, the semiconductor refrigeration plate is composed of two different types of semiconductor materials and then connected to direct current for heating and cooling. The two semiconductor materials for semiconductor heating and cooling are P-type and N-type semiconductor sheets, and the P-type semiconductor surface is the heating surface ( Figure 6 The pink surface in the middle), the N-type semiconductor surface is the cooling surface ( Figure 6 (blue side in the middle).

[0070] The control unit includes an infrared processing controller, an intelligent temperature controller, a temperature data acquisition controller, a PWM controller, and a temperature control circuit. The temperature data acquisition controller is used for high-speed temperature data acquisition. The PWM controller generates a PWM waveform based on instructions from the intelligent temperature controller and sends this waveform to the temperature control circuit. The temperature control circuit controls the power-on time of the semiconductor cooling chip based on the PWM waveform, achieving rapid and precise temperature control within the thiourea online pre-reduction module.

[0071] The detection circuit includes a temperature acquisition circuit, an ADC circuit, and an infrared receiving circuit. The temperature acquisition circuit amplifies and filters temperature data for real-time temperature detection within the thiourea online pre-reduction module. The ADC circuit converts analog signals into digital signals. The infrared receiving circuit receives infrared signals from an infrared remote control, identifies and converts them into electrical signals, and transmits these electrical signals to an infrared processing controller. The infrared processing controller identifies the electrical signals and obtains the corresponding temperature parameters set by the remote control. The temperature parameters are then transmitted to the intelligent temperature controller. The temperature acquisition circuit receives the temperature signal from the semiconductor refrigeration chip and transmits it to the ADC circuit for analog-to-digital conversion to generate a digital signal. The digital signal is then transmitted to the temperature data acquisition controller.

[0072] The temperature data acquisition controller processes the digital signal to obtain the current temperature data of the semiconductor refrigeration chip, and forwards it to the temperature intelligent controller. The temperature intelligent controller is used for fast and accurate temperature control. The temperature intelligent controller performs intelligent temperature control analysis based on the received temperature data and temperature parameters to obtain a temperature control signal, and sends the temperature control signal to the PWM controller. The PWM controller generates a PWM waveform based on the temperature control signal and sends the PWM waveform to the temperature control circuit. The temperature control circuit controls the power-on time of the semiconductor refrigeration chip based on the PWM waveform. The semiconductor refrigeration chip is used to provide corresponding temperature for the heating reaction and cooling reduction reaction of the thiourea online pre-reduction module under the control of the temperature control circuit.

[0073] The collection module includes a discharge pipe and a second electric gas valve. One end of the discharge pipe is connected to the discharge port of the thiourea online pre-reduction module, and the other end of the discharge pipe is connected to the micro-gas-liquid separation chip. The second electric gas valve is installed on the discharge pipe. The discharge pipe is used to input the hydrogen selenide generated by reduction into the micro-gas-liquid separation chip; the second electric gas valve is used to control the injection amount of hydrogen selenide gas into the micro-liquid storage mixing module.

[0074] H2Se is allowed to enter the micro-gas-liquid separation chip of the micro-plasma atomic emission spectrometry online combined integrated system through the sample outlet tube and the electric gas valve to realize the rapid determination of trace elements by online combined technology.

[0075] In view of the defects of the electrochemical method, electron activation method and other methods used in the prior art for determining selenium content, a microfluidic technology with weak interference, simple operation, low cost and controllable process is considered to determine selenium content. A microfluidic chip is provided in an embodiment of the present invention. The sampling module is used to sample and pressurize the reaction liquid and the carrier gas. After the reaction liquid enters the micro-liquid storage mixing module, it is mixed in the mixing channel. After pressurization, the mixed liquid enters the reaction zone of the thiourea online pre-reduction module. Under the heating action of the semiconductor refrigeration module, efficient heat transfer is achieved and the synthesis reaction is completed in the reaction channel. After the reaction is completed, it enters the reduction refrigeration zone. Under the refrigeration action of the semiconductor refrigeration module, efficient pre-reduction is achieved. After the reduction is completed, the measured selenium element is obtained and discharged through the discharge pipe. The technical solution provided in the embodiment of the present invention adopts an inverted triangular mixing chamber with a built-in obstacle to connect the mixing channel with an S-shaped structure and the pre-reduction channel with an S-shaped structure. It can achieve efficient mixing of the reaction liquid and the carrier gas, ensure system homogeneity, and use semiconductor heating and semiconductor refrigeration to improve heat transfer and refrigeration effects, shortening the synthesis reduction time of the selenium element.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and description of the present invention.

Claims

1. A microfluidic chip, characterized in that: include: Sampling module, micro liquid storage and mixing module, thiourea online pre-reduction module, semiconductor refrigeration module and collection module, The injection module drives the syringe pump through an external circuit to inject the sample to be mixed into the micro-liquid storage mixing module with a controllable injection volume; The micro-liquid storage and mixing module is used to fully micro-mix the digested selenium-containing sample, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid before entering the thiourea online pre-reduction module; The thiourea online pre-reduction module uses heating reaction and cooling reduction reaction to generate hydrogen selenide gas which enters the micro gas-liquid separation chip; The semiconductor refrigeration module is arranged below the thiourea online pre-reduction module and is used to control the temperature of the semiconductor refrigeration chip in real time to achieve heating reaction and cooling reduction reaction; The collecting module is used to collect the obtained hydrogen selenide gas; The micro-liquid storage and mixing module is sequentially provided with a glass base layer, a PDMS bottom layer and a micro-liquid storage and mixing layer from bottom to top, and the micro-liquid storage and mixing layer includes a connected inverted triangle mixing cavity layer and an S-shaped mixing channel layer; The inverted triangle mixing chamber layer is used for preliminary micro-mixing of the digested selenium-containing sample, thiourea, and hydrochloric acid fluid; The S-shaped mixing channel layer is used for fully micro-mixing the sample containing selenium after digestion, thiourea, and hydrochloric acid fluid after initial micro-mixing; The inverted triangular mixing chamber layer includes a plurality of circular inlets, an inverted triangular mixing chamber and a first obstacle array; The circular inlet is connected to the inverted triangular mixing chamber through a guide tube. The first obstacle array is located in the inverted triangular mixing chamber. The first obstacle array is 6 elliptical obstacles arranged in an inverted triangular array, with 3, 2, and 1 elliptical obstacles arranged from top to bottom. The size of each elliptical obstacle is the same, and the spacing between each elliptical obstacle is the same. A second obstacle is provided below the S-shaped channel of the S-shaped mixing channel layer. The second obstacle is 21 square obstacles, each of which has a different size. The square obstacles are arranged in a horizontal manner, with a total of three rows, and 7 square obstacles in each row. The spacing between the square obstacles in the first and third rows increases from left to right, and the spacing between the square obstacles in the second row increases from right to left. The thiourea online pre-reduction module includes a glass substrate layer, a PDMS bottom layer and a pre-reduction unit layer arranged in sequence from top to bottom, and the pre-reduction unit layer includes an S-shaped heating reaction zone layer and an S-shaped reduction refrigeration zone layer connected to each other; The S-shaped heating reaction zone layer fully mixes the digested selenium-containing sample, thiourea and hydrochloric acid fluid and then heats and reacts with CH4N2S to generate selenium; The S-type reduction refrigeration zone layer is used to perform a refrigeration reduction reaction between selenium and KBH4 to obtain hydrogen selenide; The collection module includes a discharge pipe and a second electric valve, one end of the discharge pipe is connected to the outlet of the thiourea online pre-reduction module, the other end of the discharge pipe is connected to the micro gas-liquid separation chip, and the second electric valve is installed on the discharge pipe. The discharge pipe is used to input the hydrogen selenide generated by reduction into the micro gas-liquid separation chip; The second electric gas valve is used to control the injection amount of hydrogen selenide gas into the micro gas-liquid separation chip.

2. The microfluidic chip according to claim 1, wherein The injection module includes a syringe pump, an injection tube, an electric liquid valve and a first electric gas valve; The injection pump is used to inject the digested selenium-containing sample, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid into the injection tube; The sample injection tube is used to input the digested selenium-containing sample, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid into the micro-liquid storage mixing module; The electric liquid valve is used to control the injection volume of the digested selenium-containing sample, thiourea, and hydrochloric acid fluid into the micro-liquid storage and mixing module; The first electric gas valve is used to control the injection amount of the carrier gas to be reacted into the micro liquid storage and mixing module; One end of the sampling tube is connected to the micro liquid storage mixing module, the other end of the sampling tube is connected to the injection pump, and the electric liquid valve and the first electric air valve are respectively installed on the sampling tube.

3. The microfluidic chip according to claim 1, wherein The semiconductor refrigeration module includes a control unit, a detection circuit and a semiconductor refrigeration chip; The control unit is used to generate a control signal for controlling the temperature of the semiconductor refrigeration chip, and the control signal includes a heating signal and a cooling signal; The detection circuit is used to collect the temperature of the semiconductor refrigeration chip in real time; The semiconductor refrigeration plate provides corresponding temperature for the thiourea online pre-reduction module to perform heating reaction and cooling reduction reaction according to the control signal of the control unit.

4. The microfluidic chip according to claim 3, wherein When the control signal is a heating signal, one end of the semiconductor refrigeration plate is a cooling end and the other end is a heat dissipation end, and the heat dissipation end is set below the S-shaped heating reaction zone layer. When the control signal is a cooling signal, one end of the semiconductor refrigeration plate is a cooling end and the other end is a cooling end, and one of the cooling ends is set below the S-shaped reduction cooling zone layer.

5. The microfluidic chip according to claim 4, characterized in that: The control unit includes an infrared processing controller, a temperature intelligent controller, a temperature data acquisition controller, a PWM controller and a temperature control circuit, and the detection circuit includes a temperature acquisition circuit, an ADC circuit and an infrared receiving circuit; The infrared receiving circuit is used to receive the infrared signal sent by the infrared remote controller, identify the infrared signal and convert it into an electrical signal, and transmit the electrical signal to the infrared processing controller; The infrared processing controller is used to identify the electrical signal to obtain the corresponding temperature parameters set by the remote control, and send the temperature parameters to the temperature intelligent controller; The temperature acquisition circuit is used to collect the temperature signal of the semiconductor refrigeration chip, and transmits the temperature signal to the ADC circuit for analog-to-digital conversion to obtain a digital signal, and transmits the digital signal to the temperature data acquisition controller; The temperature data acquisition controller processes the digital signal to obtain the current temperature data of the semiconductor refrigeration chip and forwards it to the temperature intelligent controller; The temperature intelligent controller performs intelligent temperature control analysis based on the received temperature data and temperature parameters to obtain a temperature control signal, and sends the temperature control signal to the PWM controller; The PWM controller generates a PWM waveform according to the temperature control signal and sends the PWM waveform to the temperature control circuit; The temperature control circuit controls the power-on time of the semiconductor refrigeration chip according to the PWM waveform; The semiconductor refrigeration chip is used to provide corresponding temperatures for the thiourea online pre-reduction module to perform heating reaction and cooling reduction reaction under the control of the temperature control circuit.

Images