Heavy metal synchronous detection device based on micro-fluidic chip and non-contact conductance

Abstract

The invention relates to the field of rapid detection of heavy metals in water, and particularly discloses a synchronous heavy metal detection device based on a micro-fluidic chip and non-contact conductance, the synchronous heavy metal detection device comprises the micro-fluidic chip, two non-contact conductance detectors, a high-voltage module and a main controller, the micro-fluidic chip comprises a cross-shaped micro-channel, the non-contact conductivity detector comprises a non-contact electrode, a surface acoustic wave device, a function signal generator, an adder and a data acquisition module. According to the invention, microwave interference signals generated by heavy metal ions under the action of high voltage are collected through the surface acoustic wave device, and a voltage signal opposite to the microwave interference signals is output to the adder through the function signal generator; the voltage signal and a data signal of a receiving electrode are subjected to superposition filtering through an adder, so that a heavy metal ion microwave interference signal is weakened, and the detection precision of the heavy metal ion concentration is improved.

Description

Technical Field

[0001] The invention belongs to the field of rapid detection of heavy metals in water bodies, and in particular relates to a heavy metal synchronous detection device based on a microfluidic chip and non-contact conductivity. Background Art

[0002] With the development of industry and agriculture, more and more heavy metals such as mercury, cadmium, and chromium are discharged into the water, entering the food chain through enrichment, posing a serious threat to the entire ecological environment. For the detection of the above heavy metals, there are currently mainly atomic spectroscopy, mass spectrometry, electrochemistry, capillary electrophoresis, etc. In the actual operation process, the detection equipment using the above methods has defects such as complex equipment structure, high difficulty in operation, high cost and large equipment size. It requires professional personnel to detect and cannot be quickly detected on site. When responding to sudden pollutant leaks or continuously monitoring a certain area, fast and efficient detection tools are still needed.

[0003] Based on the capillary electrophoresis method, scientists and technicians have developed a method and device for the simultaneous detection of heavy metals in water based on microfluidic chips and non-contact conductivity. The microfluidic chip integrates multiple basic operating units such as sample pretreatment, chemical reaction and separation detection on a chip with a micron or even nanometer microchannel network, and then completes the complex analysis process by applying high-pressure operating fluids. The metal ions are collected through a non-contact conductivity detector, and the electrophoresis diagram of the metal ions is drawn based on the different conductivities of different metal ions. The concentrations of various metal ions are calculated, which can quickly and accurately measure the types and contents of heavy metal ions in the sample solution.

[0004] In the existing synchronous detection device for heavy metals in water based on microfluidic chips and non-contact conductivity, metal ions in the sample solution will generate microwaves on the surface of the metal ions under the action of high voltage. These microwave signals will be collected by the non-contact electrodes of the non-contact conductivity detector and transmitted to the subsequent data amplification and detection unit, which will interfere with the detection of the heavy metal ion concentration of the sample solution to be tested and affect the detection accuracy of the heavy metal ion concentration of the sample solution to be tested. Summary of the invention

[0005] The purpose of the present invention is to provide a heavy metal synchronous detection device based on a microfluidic chip and non-contact conductivity, so as to solve the problem in the prior art that, under the action of high pressure, the heavy metal ions in the sample solution will form interference microwaves on the surface of the heavy metal ions, and these interference microwave signals are collected by the non-contact electrodes of the non-contact conductivity detector and transmitted to the data amplification and detection unit of the subsequent stage, causing interference to the detection of the heavy metal ion concentration of the sample solution to be tested, thereby affecting the detection accuracy of the heavy metal ion concentration of the sample solution to be tested.

[0006] To achieve the above object, the present invention provides a heavy metal synchronous detection device based on a microfluidic chip and non-contact conductivity, comprising:

[0007] A microfluidic chip, wherein the microfluidic chip is provided with a cross microchannel, and the cross microchannel includes a sample enrichment channel and a heavy metal ion separation channel;

[0008] Two non-contact conductivity detectors, the two non-contact conductivity detectors are respectively arranged at the bottom of the metal ion and heavy metal ion separation channel of the microfluidic chip to detect the metal ion concentration in the metal ion and heavy metal ion separation channel, the non-contact conductivity detector comprises a non-contact electrode, a surface acoustic wave device, a function signal generator, an adder and a data acquisition module, the non-contact electrode comprises an emitter and a receiver, the emitter and the receiver are respectively arranged at the upper and lower ends of the heavy metal ion separation channel, the emitter is connected to an output end of the function signal generator, and an output end of the function signal generator is connected to the data acquisition module. The surface acoustic wave device is arranged between the transmitting electrode and the receiving electrode, and is used to detect the microwave interference signal of the metal ions. The output end of the surface acoustic wave device is connected to an input end of the data acquisition module. The receiving electrode and an output end of the function signal generator are respectively connected to an input end of the adder, so that a signal with a polarity opposite to that of the microwave interference signal of the metal ions is generated by the function signal generator and input into the adder. The adder superimposes the signal collected by the receiving electrode with the output signal of the function signal generator for filtering, and the output end of the adder is connected to an input end of the data acquisition module;

[0009] A high voltage module and a main controller, wherein the high voltage module is used to inject 0-1.5 kV high voltage into the cross microchannel of the microfluidic chip to enrich metal ions in the sample enrichment channel and to separate metal anions and cations in the sample solution in the heavy metal ion separation channel, the high voltage module is connected to the main controller, and the main controller is respectively connected to the function signal generator and the data acquisition module of the two non-contact conductivity detectors.

[0010] Preferably, in the above technical solution, the data acquisition module includes a phase shift module, a preamplifier module, a phase-locked module and a high-speed AD module, the input end of the phase shift module is connected to an output end of the function signal generator, the output end of the phase shift module is connected to an input end of the phase-locked amplifier module, the input end of the preamplifier module is connected to the output end of the adder, the output end of the preamplifier module is connected to an input end of the phase-locked amplifier module, the output end of the phase-locked amplifier module is connected to the input end of the high-speed AD module, and the output end of the high-speed AD module is connected to the main controller.

[0011] Preferably, in the above technical scheme, the sample enrichment channel and the heavy metal ion separation channel are interconnected, and a sample liquid reservoir and a waste liquid reservoir are respectively provided at both ends of the sample enrichment channel, and a buffer reservoir, a cation reservoir and an anion reservoir are respectively provided at both ends of the heavy metal ion separation channel, and a wiring electrode is provided in each of the sample liquid reservoir, the waste liquid reservoir, the sample enrichment pool, the cation reservoir and the anion reservoir.

[0012] Preferably, in the above technical solution, the heavy metal ion separation channel structure is Y-shaped, and the two non-contact conductivity detectors are respectively arranged on the right side of the cross microchannel intersection area and the right end of the heavy metal ion separation channel.

[0013] Preferably, in the above technical scheme, the high-voltage module includes a PWM module, a high-voltage power supply module, a high-voltage relay group and a lithium battery module, the input end of the PWM module is connected to the main controller, the input end of the high-voltage power supply module is connected to the output end of the PWM module, the input end of the high-voltage relay group is connected to the output end of the high-voltage power supply module, and the output end of the switch array of the high-voltage relay group is respectively connected to the wiring electrodes of the sample liquid reservoir, sample enrichment pool, waste liquid pool, buffer solution reservoir, cation reservoir and anion reservoir provided in the microfluidic chip.

[0014] Preferably, in the above technical solution, it also includes a box body, which is provided with a detection chamber and a cleaning chamber, the detection chamber is provided with a mounting seat and a pressure plate, bolts are provided at both ends of the mounting seat, the microfluidic chip is detachably mounted on the mounting seat and fixed by the pressure plate, the cleaning chamber is provided with an ultrasonic cleaning device and a protective liquid to achieve cleaning of the microfluidic chip, and the ultrasonic cleaning device is connected to the main controller.

[0015] Preferably, in the above technical solution, it also includes a pH value detection board, which is installed on the box body and connected to the main controller to detect the pH value of the sample solution.

[0016] Preferably, in the above technical solution, it also includes a touch screen and a knob, and the touch screen and the knob are respectively connected to the main controller.

[0017] Preferably, in the above technical solution, it also includes a wireless communication module and a cloud system for receiving and processing heavy metal ion detection data, the wireless communication module is connected to the main controller, and the cloud system is wirelessly connected to the wireless communication module.

[0018] Compared with the existing technology, the present invention has the following beneficial effects:

[0019] 1. The present invention uses a surface acoustic wave device to treat the microwave interference signal of heavy metal ions under high pressure, and generates a signal with a polarity opposite to the microwave interference signal through a function signal generator to an adder. The adder superimposes and filters the microwave interference signal with the opposite polarity and the signal collected by the receiving electrode of the non-contact conductivity detector to eliminate the microwave interference signal on the surface of the heavy metal ions, thereby improving the detection accuracy of the metal ion concentration.

[0020] 2. The present invention shortens the detection time of heavy metal ions by using two non-contact conductivity detectors arranged at the bottom of the heavy metal ion separation channel of the microfluidic chip to simultaneously detect heavy metal ions with different flow rates, while avoiding the problem of loss of resolution during detection of heavy metal ions with fast flow rates.

[0021] 3. The present invention realizes the on-site preparation of the pH value of the test sample solution through the pH value detection plate. Through the ultrasonic cleaning device and protective liquid arranged in the cleaning chamber, the user can dismantle and clean the microfluidic chip after the sample test, which is convenient for multiple tests and uses. The test results are sent to the cloud system through the wireless communication module. The cloud system generates a test report based on the test data, realizes data detection and result uploading, so that the present invention can be applied to the portable and rapid detection needs of heavy metal ions in water bodies in various outdoor environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the overall structural diagram of the heavy metal synchronous detection device based on microfluidic chip and non-contact conductivity.

[0023] Figure 2 It is a schematic diagram of the partial structure of a heavy metal synchronous detection device based on a microfluidic chip and non-contact conductivity.

[0024] Figure 3 It is a schematic diagram of the circuit principle structure of a heavy metal synchronous detection device based on a microfluidic chip and non-contact conductivity.

[0025] Figure 4 It is a schematic diagram of the top view structure of the microfluidic chip.

[0026] Figure 5 It is a circuit structure diagram of a non-contact conductivity detector.

[0027] Figure 6 It is a schematic diagram of the connection relationship between the high-voltage relay group and the microfluidic chip.

[0028] Figure 7 It is a diagram of the electrophoresis process of the simultaneous detection of heavy metals based on microfluidic chips and non-contact conductivity detection.

[0029] Figure 8 It is a schematic diagram of the structure of a surface acoustic wave device.

[0030] In the figure: 1—box, 2—touch screen, 3—detection chamber, 4—cleaning chamber, 5—PH value detection board, 6—knob, 7—circuit board, 8—microfluidic chip, 9—first injection port, 10—second injection port, 11—third injection port, 12—fourth injection port, 13—pressing plate, 14—mounting seat, 15—wiring electrode, 100—sample enrichment channel, 101—heavy metal ion separation channel, 102—sample liquid reservoir, 103—sample enrichment pool, 104—waste liquid pool, 105—buffer reservoir, 106—cation reservoir, 107— Anion water reservoir, 200—high voltage module, 201—PWM module, 202—high voltage power supply module, 203—high voltage relay group, 204—lithium battery module, 205—main controller, 206—wireless communication module, 207—ultrasonic cleaning device, 300—non-contact conductivity detector, 301—surface acoustic wave device, 302—function signal generator, 303—phase shift module, 304—phase-locked amplifier module, 305—preamplifier module, 306—high-speed AD module, 307—emitter, 308—receiver, 309—adder. DETAILED DESCRIPTION

[0031] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings, but it should be understood that the protection scope of the invention is not limited by the specific implementation modes.

[0032] refer to Figure 1-Figure 4A heavy metal synchronous detection device based on a microfluidic chip and non-contact conductivity includes a box body 1, a detection chamber 3, a microfluidic chip 8, two non-contact conductivity detectors 300, a high-voltage module 200 and a main controller 205. The detection chamber 3 is arranged on the left side of the box body 1. A circuit board 7 is arranged in the detection chamber 3. A mounting seat 14 is fixed on the circuit board 7. Bolts are respectively arranged at both ends of the mounting seat 14. The microfluidic chip 8 is detachably mounted on the mounting seat 14 and fixed by a pressing plate 13. The microfluidic chip 8 is provided with a cross microchannel, which includes a sample enrichment channel 100 and a heavy metal ion separation channel 101 that are interconnected. A sample liquid reservoir 102 and a waste liquid pool 104 are provided at both ends of the sample enrichment channel 100, respectively. A sample enrichment pool 103 is provided near the sample liquid reservoir 102. The sample liquid reservoir 102 is connected to the sample enrichment pool 103 through a plurality of branch flow channels. The heavy metal ion separation channel 101 is Y-shaped, and a buffer reservoir 105 is provided at the head end of the heavy metal ion separation channel 101, and a cation reservoir 106 and anion reservoir 107 are provided at the tail end. A wiring electrode 15 is provided in each of the sample liquid reservoir 102, the waste liquid pool 104, the sample enrichment pool 103, the cation reservoir 106 and the anion reservoir 107. Two non-contact conductivity detectors 300 are respectively installed on the right side of the cross microchannel intersection area of ​​the microfluidic chip 8 and on the right end of the heavy metal ion separation channel 101. The high-voltage module 200 is installed on the back of the circuit board 7. The output end of the high-voltage module 200 is respectively connected to the wiring electrodes 15 arranged in the sample liquid reservoir 102, the waste liquid reservoir 104, the sample enrichment pool 103, the cation reservoir 106 and the anion reservoir 107. The high-voltage module 200 and the two non-contact conductivity detectors 300 are respectively connected to the main controller 205.

[0033] Furthermore, the sample liquid reservoir 102 is provided with a first injection port 9, the sample enrichment pool 103 is provided with a fourth injection port 12, the buffer solution reservoir 105 is provided with a second injection port 10, and the sample liquid reservoir 102 is provided with a third injection port 11 to facilitate the introduction of sample solution and buffer solution.

[0034] refer to Figure 5 and Figure 8The non-contact conductivity detector 300 includes a non-contact electrode, a surface acoustic wave device 301, a function signal generator 302, an adder 309 and a data acquisition module, wherein the data acquisition module includes a phase shift module 303, a phase-locked amplifier module 304, a preamplifier module 305 and a high-speed AD module 306, and the non-contact electrode includes an emitter 307 and a receiver 308, wherein the emitter 307 and the receiver 308 are respectively arranged at the upper and lower ends of the heavy metal ion separation channel 101, and the receiver 308 is connected to an input end of the adder 309, and the input end of the function signal generator 302 is connected to the main controller 205, and an output end of the function signal generator 302 is connected to the emitter 307 to generate a 10-80V AC excitation sampling signal u 1. Due to the polarization phenomenon, a current signal i1 of the same frequency will be induced at the receiving electrode 308. The surface acoustic wave device 301 is arranged between the transmitting electrode 307 and the receiving electrode 308, and is used to collect the metal ion microwave interference signal of the heavy metal ion separation channel 101. The output end of the surface acoustic wave device 301 is connected to the high-speed AD module 306 of the data acquisition module. The microwave interference signal is formed on the surface of the metal ions under the action of high pressure by the heavy metal ions. In the sample solution, it will propagate in the heavy metal ion separation channel 101 in the form of high-frequency sound waves, which can be recognized by the sensitive membrane of the surface acoustic wave device 301, and the sound signal is converted into a voltage signal u6 by the interdigital transducer of the surface acoustic wave device 301 for output and sent to the high-speed AD module 306 for collection. An output end of the function signal generator 302 and an input end of the adder 309 are used to generate a voltage signal u3 with the same frequency and amplitude but opposite polarity to the microwave interference signal collected by the surface acoustic wave device 301, and the voltage signal u3 is superimposed and filtered with the current signal i1 sensed by the receiving electrode 308 through the adder 309 to output a voltage signal u5, so as to weaken the microwave interference signal on the surface of the heavy metal ions and improve the sampling accuracy of the heavy metal ions. In this embodiment, a 1Ω resistor R1 is connected in parallel between the adder 309 and the receiving electrode 308 to convert the current signal i1 into a voltage signal u2 and input it into the adder 309.

[0035] Furthermore, the output end of the adder 309 is connected to the preamplifier module 305, an output end of the function signal generator 302 is connected to the phase shift module 303, the output ends of the phase shift module 303 and the preamplifier module 305 are respectively connected to the phase-locked amplifier module 304, the output end of the phase-locked amplifier module 304 is connected to the high-speed AD module 306, and the output end of the high-speed AD module 306 is connected to the main controller 205, wherein the preamplifier module 305 is used to convert the voltage signal u5 of the adder 309 into a voltage signal u7 with the same frequency as the sampling signal u1, the function signal generator 302 is used to output a reference signal u4 with the same frequency as u1, the phase shift module 303 is used to adjust the reference signal u4 to a voltage signal u9 with the same phase as the voltage signal u7, and then, the phase-locked amplifier module 304 outputs a voltage signal u8. In this embodiment, the phase-locked amplifier module 304 is composed of a multiplier, a second-order low-pass filter and an amplifier connected in sequence, and the voltage signal u7 and the voltage signal u9 are transmitted through When the multiplier of the phase-locked amplifier module 304 multiplies, a double frequency signal and a DC voltage signal are obtained. The double frequency signal is filtered out by a second-order low-pass filter, leaving only the DC voltage signal, which is then amplified by the amplifier to output the voltage signal u8. The high-speed AD module 306 is used to convert the collected voltage signal u8 and the voltage signal u6 into digital quantities for collection by the main controller 205. When ions pass through the area between the emitter 307 and the receiver 308, the amplitude of the voltage signal u5 will change due to electromagnetic induction, and the ion concentration information is included in the amplitude change. On the basis of the weakening of the ion microwave interference signal, the voltage signal u8 obtained by amplification processing by the phase-locked amplifier module 304 can be more easily collected by the high-speed AD module 306. The main controller 205 calculates and processes the amplitude change information of the voltage signal u8 sent by the high-speed AD module 306, and converts it into metal ion concentration data, thereby further improving the effectiveness of the signal and improving the signal-to-noise ratio and sensitivity of the system. In this embodiment, the phase shift module 303 can be composed of a voltage follower, a first-stage phase shift circuit, a second-stage phase shift circuit and a common-phase proportional amplifier circuit connected in sequence. The operational amplifiers at each stage can be composed of an operational amplifier chip of model OP42. The multiplier of the phase-locked amplifier module 304 adopts an MPY634 multiplier. The operational amplifiers used in the second-order low-pass filter and the amplifier can adopt an operational amplifier chip of OP42. The main controller 205 can use a processor chip of model STM32F407IGT6.

[0036] Furthermore, since different heavy metal ions have different electrical conductivities, the flow rates of heavy metal ions under high pressure are also different, forming different sample bands. The non-contact conductivity detector 300 installed on the right side of the cross microchannel intersection area of ​​the microfluidic chip 8 is used to collect the heavy metal ion sample band with a slower flow rate, and the non-contact conductivity detector 300 installed on the right end of the heavy metal ion separation channel 101 is used to collect the sample band formed by the heavy metal ions with a slower flow rate, thereby realizing the synchronous collection of heavy metal ions with different flow rates, shortening the detection time of heavy metal ions, and avoiding the problem of loss of resolution when detecting heavy metal ions with a fast flow rate.

[0037] refer to Figure 3 The high-voltage module 200 includes a PWM module 201, a high-voltage power module 202, a high-voltage relay group 203 and a lithium battery module 204. The input ends of the PWM module 201 and the high-voltage relay group 203 are respectively connected to the main controller 205, the input end of the high-voltage power module 202 is connected to the output end of the PWM module 201, the input end of the high-voltage relay group 203 is connected to the output end of the high-voltage power module 202, and the switch array output end of the high-voltage relay group 203 is respectively connected to the wiring electrodes 15 of the sample liquid reservoir 102, the sample enrichment pool 103, the waste liquid pool 104, the buffer reservoir 105, the cation reservoir 106 and the anion reservoir 107 of the microfluidic chip 8. In this embodiment, the high-voltage power module 202 can use a model HVW12X-D1500NR5 module, which can output a DC voltage of 0-1.5kV.

[0038] Continue to refer Figure 1The present invention also includes a touch screen 2, a pH value detection board 5, a wireless communication module 206, a cloud system for receiving and processing heavy metal ion detection data, a knob 6 and a cleaning chamber 4 installed on the box body 1. The cleaning chamber 4 is provided with an ultra-ultrasonic cleaning device 207 and deionized water. The touch screen 2, the ultrasonic cleaning device 207, the pH value detection board 5, the wireless communication module 206 and the knob 6 are respectively connected to the main controller 205. The cloud system is wirelessly connected to the wireless communication module 206. The knob 6 is used to adjust the output voltage of the high-voltage module 200. The touch screen 2 is used for inputting user operations and metal ion concentration. The output results are displayed, the cloud system is used to receive and process heavy metal ion detection data, and generate data reports. The ultrasonic cleaning device 207 and deionized water in the cleaning chamber 4 are used for cleaning the microfluidic chip 8 during outdoor detection work, which is convenient for multiple uses of the microfluidic chip 8. The pH value detection board 5 is used for on-site detection work to measure the pH value of the sample solution. Through the pH value detection board 5, the cloud system and the ultrasonic cleaning device 207, the present invention can be suitable for the portable and rapid detection of heavy metal ions in water bodies in various outdoor environments. In this embodiment, the wireless communication module 206 can adopt a 4G unlimited communication module.

[0039] Specifically, the above-mentioned device for synchronously detecting heavy metal ions in water based on microfluidic chip and non-contact conductivity detection includes the following steps:

[0040] (1) preparing a sample solution to be tested: taking a sample stock solution and mixing it with a low concentration buffer solution, wherein the components of the low concentration buffer solution include histidine, morphine ethanesulfonic acid, 18-crown ether-6 and deionized water, and then adding an acid to lower its pH value, and detecting the pH value of the mixed solution by a pH value detection plate 5 to obtain a sample solution to be tested with a pH value of 6;

[0041] Prepare a high-concentration buffer with the same composition as the low-concentration buffer;

[0042] (2) The sample solution is drawn through a pipette and dripped into the first injection port 9 so that the sample solution fills the sample solution reservoir 102; a low concentration buffer solution is dripped into the fourth injection port 12 so that the low concentration buffer solution fills the sample enrichment pool 103 and the upper half of the sample enrichment channel 100; a high concentration buffer solution is dripped into the second injection port 10 and the third injection port 11 so that the high concentration buffer solution fills the waste liquid pool 104, the buffer solution reservoir 105, the lower half of the sample enrichment channel 100, the heavy metal ion separation channel 101, the cation reservoir 106 and the anion reservoir 107.

[0043] (3) Figure 6 and Figure 7As shown in (A), the main controller 205 controls the PWM module 201 to output modulated pulses, so that the high-voltage power supply module 202 outputs a voltage of 400V, and controls the high-voltage relay group 203 to close switches K1 and K3, so that the sample liquid reservoir 102 is connected to a voltage of 400V, and the sample enrichment pool 103 is grounded. The heavy metal ions in the sample solution migrate from the sample liquid reservoir 102 to the sample enrichment pool 103, and the first enrichment of heavy metal ions is achieved. The operation time of this step is 30 seconds. After 30 seconds, the main controller 205 controls the high-voltage relay group 203 to disconnect switches K1 and K3.

[0044] (4) Figure 6 and Figure 7 As shown in (B), the main controller 205 controls the PWM module 201 to output modulated pulses, so that the high-voltage power supply module 202 outputs a voltage of 300V, and controls the high-voltage relay group 203 to close switches K2 and K7, so that the sample enrichment pool 103 is connected to a voltage of 300V, and the waste liquid pool 104 is grounded. The heavy metal ions in the sample solution migrate from the sample enrichment pool 103 to the waste liquid pool 104, and the heavy metal ions are enriched for the second time on the step surface of the low-concentration buffer and the high-concentration buffer. The operation time of this step is 10 seconds. After 10 seconds, the main controller 205 controls the high-voltage relay group 203 to disconnect switches K2 and K7.

[0045] Through the two steps (3) and (4), the enrichment efficiency of metal ions in the sample solution is improved, so that accurate detection can be achieved with as little sample as possible, thereby reducing the use of reagents.

[0046] (5) Figure 6 and Figure 7 As shown in (C), the main controller 205 controls the PWM module 201 to output a modulated pulse, so that the high-voltage power supply module 202 outputs a 1kV voltage, and controls the high-voltage relay group 203 to close switches K4 and K8, so that the buffer reservoir 105 is connected to a 1kV voltage, and the cation reservoir 106 is grounded. The heavy metal cations in the sample solution migrate from the step surface of the low-concentration buffer solution and the high-concentration buffer solution to the cation reservoir 106. During this period, the heavy metal cations with different conductivity form a sample due to the different flow rates in the flow channel under the action of the electric field force. The heavy metal cations with a faster flow rate are detected by the non-contact conductivity detector 300 arranged at the right end of the heavy metal ion separation channel 101, and the heavy metal cations with a slower flow rate are detected by the non-contact conductivity detector 300 arranged at the right side of the cross microchannel intersection area, so as to shorten the detection time, improve the detection accuracy, and avoid the loss of heavy metal cation resolution. The operation time of this step is 40 seconds. After 40 seconds, the main controller 205 controls the high-voltage relay group 203 to disconnect the switches K4 and K8 to complete the separation and detection of heavy metal cations.

[0047] (6) Figure 6 , Figure 7 (D) and Figure 7 As shown in (E), the main controller 205 controls the PWM module 201 to output a modulated pulse, so that the high-voltage power supply module 202 outputs a voltage of 500V, and controls the high-voltage relay group 203 to close switches K3 and K6, so that the waste liquid pool 104 is connected to a voltage of 500V, the sample enrichment pool 103 is grounded, and the heavy metal anions in the sample solution migrate from the step surface of the low-concentration buffer solution and the high-concentration buffer solution to the waste liquid pool 104. After this step lasts for 10 seconds, the main controller 205 controls the high-voltage relay group 203 to disconnect switches K3 and K6. The main controller 205 controls the PWM module 201 to output a modulated pulse, so that the high-voltage power supply module 202 outputs a voltage of 1kV, and controls the high-voltage relay group 203 to close switches K5 and K9, so that the anion reservoir 107 is connected to a voltage of 1kV, and the buffer reservoir 105 is grounded. During this period, under the action of the electric field force, heavy metal anions with different conductivities form sample bands due to their different flow rates in the flow channel, wherein the heavy metal anions with faster flow rates are detected by the non-contact conductivity detector 300 arranged at the right end of the heavy metal ion separation channel 101, and the heavy metal cations with slower flow rates are detected by the non-contact conductivity detector 300 arranged at the right side of the cross microchannel intersection area, thereby shortening the detection time, improving the detection accuracy, and avoiding the loss of heavy metal anion resolution. The operation time of this step is 40 seconds. After 40 seconds, the main controller 205 controls the high-voltage relay group 203 to disconnect switches K3 and K9 to complete the separation and detection of heavy metal anions.

[0048] The foregoing description of specific exemplary embodiments of the present invention is for the purpose of illustration and demonstration. These descriptions are not intended to limit the present invention to the precise form disclosed, and it is clear that many changes and variations can be made based on the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the present invention and its practical application, so that those skilled in the art can realize and utilize various different exemplary embodiments of the present invention and various different selections and changes. The scope of the present invention is intended to be limited by the claims and their equivalents.

Claims

1. A heavy metal synchronous detection device based on microfluidic chip and non-contact conductivity, characterized in that: include: A microfluidic chip, wherein the microfluidic chip is provided with a cross microchannel, and the cross microchannel includes a sample enrichment channel and a heavy metal ion separation channel; Two non-contact conductivity detectors, the two non-contact conductivity detectors are respectively arranged at the bottom of the metal ion and heavy metal ion separation channel of the microfluidic chip, the non-contact conductivity detector comprises a non-contact electrode, a surface acoustic wave device, a function signal generator, an adder and a data acquisition module, the non-contact electrode comprises an emitter and a receiver, the emitter and the receiver are respectively arranged at the upper and lower ends of the heavy metal ion separation channel, the emitter is connected to an output end of the function signal generator, an output end of the function signal generator is connected to the data acquisition module, the surface acoustic wave device is arranged between the emitter and the receiver, the output end of the surface acoustic wave device is connected to an input end of the data acquisition module, the receiver and an output end of the function signal generator are respectively connected to an input end of the adder, so as to generate a signal with a polarity opposite to the microwave interference signal of the metal ion through the function signal generator and input it into the adder, and the output end of the adder is connected to an input end of the data acquisition module; A high voltage module and a main controller, wherein the high voltage module is connected to the main controller, and the main controller is respectively connected to the function signal generator and the data acquisition module of the two non-contact conductivity detectors.

2. A heavy metal synchronous detection device based on microfluidic chip and non-contact conductivity according to claim 1, characterized in that: The data acquisition module includes a phase shift module, a preamplifier module, a phase lock module and a high-speed AD module. The input end of the phase shift module is connected to an output end of the function signal generator, the output end of the phase shift module is connected to an input end of the phase lock amplifier module, the input end of the preamplifier module is connected to the output end of the adder, the output end of the preamplifier module is connected to an input end of the phase lock amplifier module, the output end of the phase lock amplifier module is connected to the input end of the high-speed AD module, and the output end of the high-speed AD module is connected to the main controller.

3. The heavy metal synchronous detection device based on microfluidic chip and non-contact conductivity according to claim 1 is characterized in that: The sample enrichment channel and the heavy metal ion separation channel are interconnected, and a sample liquid reservoir and a waste liquid reservoir are respectively provided at both ends of the sample enrichment channel, and a buffer reservoir, a cation reservoir and an anion reservoir are respectively provided at both ends of the heavy metal ion separation channel, and a wiring electrode is provided in each of the sample liquid reservoir, the waste liquid reservoir, the sample enrichment pool, the cation reservoir and the anion reservoir.

4. The heavy metal synchronous detection device based on microfluidic chip and non-contact conductivity according to claim 3 is characterized in that: The heavy metal ion separation channel has a Y-shaped structure, and the two non-contact conductivity detectors are respectively arranged on the right side of the cross microchannel intersection area and the right end of the heavy metal ion separation channel.

5. The heavy metal synchronous detection device based on microfluidic chip and non-contact conductivity according to claim 1, characterized in that: The high-voltage module includes a PWM module, a high-voltage power supply module, a high-voltage relay group and a lithium battery module. The input end of the PWM module is connected to the main controller, the input end of the high-voltage power supply module is connected to the output end of the PWM module, the input end of the high-voltage relay group is connected to the output end of the high-voltage power supply module, and the output end of the switch array of the high-voltage relay group is respectively connected to the wiring electrodes of the sample liquid reservoir, the sample enrichment pool, the waste liquid pool, the buffer reservoir, the cation reservoir and the anion reservoir arranged on the microfluidic chip.

6. The heavy metal synchronous detection device based on microfluidic chip and non-contact conductivity according to claim 1, characterized in that: It also includes a box body, which is provided with a detection chamber and a cleaning chamber. A mounting seat and a pressure plate are provided in the detection chamber. Bolts are provided at both ends of the mounting seat. The microfluidic chip is detachably mounted on the mounting seat and fixed by the pressure plate. An ultrasonic cleaning device and a protective liquid are provided in the cleaning chamber to clean the microfluidic chip. The ultrasonic cleaning device is connected to the main controller.

7. The heavy metal synchronous detection device based on microfluidic chip and non-contact conductivity according to claim 1, characterized in that: It also includes a pH value detection board, which is installed on the box body and connected to the main controller.

8. The heavy metal synchronous detection device based on microfluidic chip and non-contact conductivity according to claim 1, characterized in that: It also includes a touch screen and a knob, and the touch screen and the knob are respectively connected to the main controller.

9. The heavy metal synchronous detection device based on microfluidic chip and non-contact conductivity according to claim 1, characterized in that: It also includes a wireless communication module and a cloud system for receiving and processing heavy metal ion detection data. The wireless communication module is connected to the main controller, and the cloud system is wirelessly connected to the wireless communication module.

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