Micro-fluidic chip

Abstract

The micro-fluidic chip is characterized in that a sample injection module drives an injection pump through an external circuit to inject a to-be-mixed sample into a micro liquid storage mixing module under the condition that the injection amount is controllable; the micro-storage liquid mixing module is used for enabling a digested selenium-containing sample, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid to enter the thiourea online pre-reduction module after full micro-mixing; the thiourea online pre-reduction module adopts a heating reaction and a refrigeration reduction reaction to generate hydrogen selenide gas, and the hydrogen selenide gas enters the micro gas-liquid separation chip; the semiconductor refrigeration module is arranged below the thiourea online pre-reduction module and is used for controlling the temperature of a semiconductor refrigeration sheet in real time so as to realize a heating reaction and a refrigeration reduction reaction; and the collecting module is used for collecting the obtained hydrogen selenide gas. Samples are uniformly mixed through the micro-storage liquid mixing module, and then a heating reaction and a refrigeration reduction reaction are performed through a reaction zone of the thiourea online pre-reduction module to generate hydrogen selenide gas, so that the synthesis reduction time of the selenium element is shortened.

Description

Technical Field

[0001] The invention relates to the technical field of microfluidic chips, and in particular to a microfluidic chip comprising 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), is a technology that integrates basic operating units such as sample preparation, reaction, separation, and detection in biological, chemical, and medical analysis processes onto a micrometer-scale chip, which can automatically complete 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 accurately control the reaction synthesis of fluids in micrometer to nanometer-level spaces, thereby achieving efficient and accurate determination of trace element content.

[0003] In recent years, the research on online combined technology of microfluidic chips mainly focuses on the use of micro-mixing devices for efficient micro-mixing to achieve subsequent reaction detection. Among them, the rapid determination methods for trace elements (such as selenium) mainly include electrochemical methods, electron activation methods, fluorescence spectrophotometry, inductively coupled plasma mass spectrometry, atomic spectroscopy, etc. For example, for the rapid determination of selenium, a glass beaker is often used as a container. After adding the digested selenium-containing sample, HCL and thiourea to the first glass beaker, a mixing reaction is carried out through a semiconductor electronic refrigerator at the bottom of the beaker. The sample after the mixed reaction is transferred to the second beaker, and then Ar and KBH4 are added and pre-reduced by an ultrasonic mixer to generate hydrogen selenide gas. After the micro-mixing, the hydrogen selenide gas enters the gas-liquid separator to achieve the determination of selenium. The above-mentioned method for determining selenium has the problems of serious interference in the measured value, complicated 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 to assist, which increases the cost and difficulty of operation. The samples after the mixed reaction need to be transferred in auxiliary containers. There is interference during the transfer process, which interferes with the accuracy of the measured value. The morphology of the sample will also increase the difficulty of transfer.

[0004] Based on the above problems, based on microfluidic technology. 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 mixed thoroughly, the subsequent reaction will be insufficient to obtain the required sample or the amount of sample obtained is insufficient, and the reduction reaction cannot be carried out to generate hydrogen selenide gas. 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 injection pump through an external circuit to inject the sample to be mixed into the micro-liquid storage mixing module with a controllable injection amount;

[0008] The micro-liquid storage and mixing module is used for fully micro-mixing the sample containing selenium after digestion, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid, and then 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 sheet in real time to realize the heating reaction and the refrigeration reduction reaction;

[0011] The collecting 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 sample containing selenium after digestion, 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 amount of the sample containing selenium, thiourea and hydrochloric acid fluid after digestion into the micro liquid storage 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 mixing module;

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

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

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

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

[0021] Optionally, the inverted triangular mixing chamber layer comprises a plurality of circular inlets, an inverted triangular mixing chamber body 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 obstacles are 6 elliptical obstacles, which are arranged in an inverted triangular array. From top to bottom, the numbers of elliptical obstacles are 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, and 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 row and the third row 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 comprises 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 comprises 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 micro-mixes the sample containing selenium after digestion, 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 sheet;

[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 and convert the infrared signal 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 for 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 sheet is used to provide corresponding temperature 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, and 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, and achieves efficient pre-reduction under the refrigeration action of the semiconductor refrigeration module. After the reduction is completed, the measured selenium element is obtained and discharged 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] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual 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 A simulated concentration cloud diagram of mixing performed by a micro-liquid storage mixing module is shown;

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

[0053] Figure 7 A schematic structural diagram of a semiconductor refrigeration module is shown. DETAILED DESCRIPTION

[0054] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

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

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

[0058] As used in this specification and the appended claims, the term "if" may be interpreted as "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrases "if it is determined" or "if [described condition or event] is detected" may 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, including 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 for fully micro-mixing the sample containing selenium after digestion, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid, and then entering the thiourea online pre-reduction module. The thiourea online pre-reduction module uses heating reaction and refrigeration reduction reaction to generate hydrogen selenide gas to enter 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 sheet in real time to realize heating reaction and refrigeration 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 pump in the sampling module, the sampling area 1 is the entrance of the sample containing Se (VI) after digestion, the sampling area is the entrance of 2 thiourea (TU), the sampling area 3 is the entrance of HCL fluid, the sampling area 4 is the entrance of carrier fluid 1, the sampling area 5 is the entrance of the standby carrier fluid, the sampling area 6 is the entrance 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-type mixing channel layer 8, the S-type 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 thiourea (TU) online pre-reduction module reduction refrigeration zone 10, a semiconductor heating plate 11 is arranged in the heating reaction zone 9, a semiconductor refrigeration plate 12 is arranged 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 injection module includes a syringe pump, an injection tube, an electric liquid valve and a first electric gas valve, and the syringe pump is used to inject the sample containing selenium after digestion, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid into the injection tube. The injection tube is used to input the sample containing selenium after digestion, 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 amount of the sample containing selenium, thiourea and hydrochloric acid fluid flowing into the micro-liquid storage mixing module after digestion. The first electric gas valve is used to control the injection amount of the carrier gas to be reacted into the micro-liquid storage mixing module. One end of the injection tube is connected to the micro-liquid storage mixing module, and the other end of the injection tube is connected to the syringe pump, and the electric liquid valve and the first electric gas valve are respectively installed on the injection tube. The injection module drives the syringe pump through an external circuit to simultaneously inject the sample containing Se (VI) after digestion, TU, HCL, Ar carrier gas and carrier fluid, and at the same time opens the electric liquid valve and electric gas valve on the injection tube, so that the sample enters the micro-liquid storage mixing module under the condition of controlling the amount, so as to realize the injection of the sample.

[0062] like Figure 4 As shown, the micro-liquid storage mixing module is provided with a glass substrate layer, a PDMS (polydimethylsiloxane) bottom layer and a micro-liquid storage mixing layer from bottom to top. The micro-liquid storage mixing layer includes an inverted triangle mixing cavity layer and an S-shaped mixing channel layer connected to each other. The inverted triangle mixing cavity layer is used for preliminary micro-mixing of the sample containing selenium after digestion, thiourea, and hydrochloric acid fluid; the S-shaped mixing channel layer is used for full micro-mixing of the sample containing selenium after digestion, thiourea, and hydrochloric acid fluid after preliminary micro-mixing. Figure 5 As shown, a simulated concentration cloud diagram of mixing performed by a micro-liquid storage mixing module is shown.

[0063] The inverted triangle mixing chamber layer includes a plurality of circular inlets, an inverted triangle mixing chamber and a first obstacle array. In this embodiment, five circular inlets are used, which are connected to the inverted triangle mixing chamber through a guide tube. The first obstacle array is located in the inverted triangle mixing chamber. The first obstacle is six elliptical obstacles arranged in an inverted triangle 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 inverted triangle mixing chamber is 2000um, and the size of the elliptical obstacle in the inverted triangle mixing chamber is short axis length = 300um, long axis length = 400um, and the spacing between the elliptical obstacles is 800um.

[0064] Among them, a second obstacle is set below the S-shaped channel of the S-shaped mixing channel layer. The second obstacle is 21 square obstacles. The size of each square obstacle is different. The square obstacles are arranged in a horizontal arrangement. There are three rows in total, and 7 square obstacles are arranged 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. The width of the channel containing square obstacles below the S-shaped mixing channel is 1400um, and the width of the channel without obstacles above is 1000um. The size of the square obstacles of the S-shaped rotary mixing channel is 10um to 60um in length and 1400um in width. The spacing between the square obstacles is 40um, 50um, 60um, 70um, 80um, 90um, and 100um in the first and third rows from left to right, and 40um, 50um, 60um, 70um, 80um, 90um, and 100um in the second row from right to left.

[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, so as to achieve effective mixing of samples. 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 makes different fluids mix on a smaller spatial scale. When the fluid bypasses the obstacle, the fluid converges again. Due to the difference in flow velocity and flow direction, the fluid will generate shear force and vortex in the confluence area. It can greatly increase the contact area between fluids, break the original laminar structure, and make different fluid molecules 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 the square obstacles with a height of 300um will form a capillary effect. Due to the combined effect of the viscosity between the liquid and the wall and the surface tension of the liquid, different fluids will be spontaneously absorbed after passing through the obstacle spacing, and the flow path of the fluid has changed, increasing the contact opportunities of different fluids, so that the sample can be fully micro-mixed 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-type heating reaction zone layer and an S-type reduction refrigeration zone layer connected to each other. The S-type heating reaction zone layer fully micro-mixes the sample containing selenium after digestion, 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 on selenium and KBH4 to obtain hydrogen selenide.

[0067] The thiourea (TU) online pre-reduction module realizes the reaction and reduction of selenium through heating and cooling of semiconductors. H2SeO4 containing selenium flows into the S-shaped heating reaction zone. At this time, H2SeO4 reacts with CH4N2S to produce hexavalent Se under the heating of the semiconductor wafer. 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 side in the middle), the N-type semiconductor side is the cooling side ( Figure 6 (blue side in the middle).

[0070] 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. The temperature data acquisition controller is used for high-speed temperature data acquisition. The PWM controller is used to generate a PWM waveform according to the instructions given by the temperature intelligent controller, and send 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 to achieve fast and accurate temperature control in 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 realizes temperature data amplification and filtering, and is used to detect the temperature in the thiourea online pre-reduction module in real time. The ADC circuit is used to realize the conversion from analog signal to digital signal. The infrared receiving circuit is used to receive the infrared signal sent by the infrared remote controller, and recognize and convert the infrared signal into an electrical signal, and transmit the electrical signal to the infrared processing controller. The infrared processing controller is used to recognize the electrical signal to obtain the corresponding temperature parameter set by the remote control, and send the temperature parameter to the temperature intelligent controller. The temperature acquisition circuit is used for the temperature signal of the semiconductor refrigeration plate, 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.

[0072] The temperature data acquisition controller processes the digital signal to obtain the current temperature data of the semiconductor refrigerator, 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 refrigerator based on the PWM waveform. The semiconductor refrigerator is used to provide corresponding temperatures 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 injected into the micro-liquid storage mixing module.

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

[0075] In view of the defects of the electrochemical method, the electronic activation method and other methods used in the prior art for determining the selenium content, the microfluidic technology with weak interference, simple operation, low cost and controllable process is considered to determine the selenium content. A microfluidic chip provided by an embodiment of the present invention, the sampling module is used for sampling and pressurizing the reaction liquid and the carrier gas, and the reaction liquid enters the micro-liquid storage mixing module and realizes mixing in the mixing channel. After pressurization, the mixed liquid enters the reaction zone of the thiourea online pre-reduction module, realizes efficient heat transfer under the heating action of the semiconductor refrigeration module and completes the synthesis reaction in the reaction channel, enters the reduction refrigeration zone after the reaction is completed, realizes efficient pre-reduction under the refrigeration action of the semiconductor refrigeration module, obtains the determined 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 realize 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 effect, 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 aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. These modifications or replacements do not make the essence of the corresponding technical solutions deviate 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 specification of the present invention.

Claims

1. A microfluidic chip, characterized in that: include: Injection module, micro liquid storage and mixing module, thiourea online pre-reduction module, semiconductor refrigeration module and collection module, The injection module drives the injection pump through an external circuit to inject the sample to be mixed into the micro-liquid storage mixing module with a controllable injection amount; The micro-liquid storage and mixing module is used for fully micro-mixing the sample containing selenium after digestion, thiourea, hydrochloric acid fluid, carrier gas and carrier fluid, and then 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 sheet in real time to realize the heating reaction and the refrigeration reduction reaction; The collecting module is used to collect the obtained hydrogen selenide gas.

2. The microfluidic chip according to claim 1, characterized in that: 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 sample containing selenium after digestion, 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 amount of the sample containing selenium after digestion, thiourea, and hydrochloric acid fluid flowing into the micro liquid storage 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 mixing module; One end of the injection tube is connected to the micro liquid storage mixing module, the other end of the injection tube is connected to the injection pump, and the electric liquid valve and the first electric gas valve are respectively installed on the injection tube.

3. The microfluidic chip according to claim 1, characterized in that: The micro-liquid storage mixing module is provided with a glass substrate layer, a PDMS bottom layer and a micro-liquid storage mixing layer in sequence from bottom to top, and the micro-liquid storage mixing layer includes an inverted triangle mixing cavity layer and an S-shaped mixing channel layer that are connected; The inverted triangle mixing chamber layer is used for preliminary micro-mixing of the sample containing selenium after digestion, 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 preliminary micro-mixing.

4. The microfluidic chip according to claim 3, characterized in that: The inverted triangular mixing chamber layer includes a plurality of circular inlets, an inverted triangular mixing chamber body 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 obstacles are 6 elliptical obstacles, which are arranged in an inverted triangular array. From top to bottom, the numbers of elliptical obstacles are 3, 2, and 1. The size of each elliptical obstacle is the same, and the spacing between each elliptical obstacle is the same.

5. The microfluidic chip according to claim 4, characterized in that: A second obstacle is arranged below the S-shaped channel of the S-shaped mixing channel layer. The second obstacle is 21 square obstacles. The size of each square obstacle is different. The square obstacles are arranged horizontally, with a total of three rows. There are 7 square obstacles in each row. The spacing between the first row and the third row of square obstacles increases from left to right, and the spacing between the second row of square obstacles increases from right to left.

6. The microfluidic chip according to claim 3, characterized in that: The thiourea online pre-reduction module comprises a glass substrate layer, a PDMS bottom layer and a pre-reduction unit layer arranged in sequence from top to bottom, wherein the pre-reduction unit layer comprises 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 sample containing selenium after digestion, 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 on selenium and KBH4 to obtain hydrogen selenide.

7. The microfluidic chip according to claim 6, characterized in that: The semiconductor refrigeration module includes a control unit, a detection circuit and a semiconductor refrigeration sheet; 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.

8. The microfluidic chip according to claim 7, characterized in that: 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 arranged 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 arranged below the S-shaped reduction cooling zone layer.

9. The microfluidic chip according to claim 8, 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 and convert the infrared signal 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 for 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 sheet is used to provide corresponding temperature for the thiourea online pre-reduction module to perform heating reaction and cooling reduction reaction under the control of the temperature control circuit.

10. The microfluidic chip according to claim 1, characterized in that: The collection module includes a discharge pipe and a second electric gas 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 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.

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