WO2021088304A1 - 电极修饰的重金属离子微流控检测芯片及制备方法 - Google Patents

电极修饰的重金属离子微流控检测芯片及制备方法 Download PDF

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WO2021088304A1
WO2021088304A1 PCT/CN2020/081674 CN2020081674W WO2021088304A1 WO 2021088304 A1 WO2021088304 A1 WO 2021088304A1 CN 2020081674 W CN2020081674 W CN 2020081674W WO 2021088304 A1 WO2021088304 A1 WO 2021088304A1
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electrode
sensor
microfluidic
nimn
microchannel
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PCT/CN2020/081674
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English (en)
French (fr)
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洪颖
陈建松
黄娟
吴仰耘
田玲玲
王伟
安伟
王金陵
朱园园
唐晨
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江苏扬子检验认证有限公司
金陵海关技术中心
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Priority to US17/774,174 priority Critical patent/US20220349852A1/en
Publication of WO2021088304A1 publication Critical patent/WO2021088304A1/zh

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    • B01L3/502715—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip characterised by interfacing components, e.g. fluidic, electrical, optical or mechanical interfaces
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
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    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
    • G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
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    • G01N27/30—Electrodes, e.g. test electrodes; Half-cells
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    • G01N27/48—Systems using polarography, i.e. measuring changes in current under a slowly-varying voltage
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    • B01L2300/0627—Sensor or part of a sensor is integrated
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    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B01L2300/0809—Geometry, shape and general structure rectangular shaped
    • B01L2300/0816—Cards, e.g. flat sample carriers usually with flow in two horizontal directions
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    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B01L3/50—Containers for the purpose of retaining a material to be analysed, e.g. test tubes
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    • B01L3/5027—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip
    • B01L3/502707—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip characterised by the manufacture of the container or its components
    • B—PERFORMING OPERATIONS; TRANSPORTING
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    • B33Y70/00—Materials specially adapted for additive manufacturing

Definitions

  • the invention belongs to the technical field of electrochemical detection, and particularly relates to an electrode-modified microfluidic detection chip for heavy metal ions.
  • the invention also provides a method for preparing the microfluidic chip.
  • Heavy metals are one of the most important pollutants in electronic waste. They are widely present in electronic and electrical products. If raw materials, products or wastes are not well controlled, heavy metals will directly enter the soil, water and atmosphere, causing direct pollution. Indirect pollution is caused by mutual migration between different environments. Because heavy metals are not degradable, they can migrate and accumulate through the food chain and eventually be ingested by the human body and accumulated in the organs, and the ingested heavy metals are difficult to be excreted from the body.
  • the heavy metals in the human body are easily combined with proteins and enzymes to cause their inactivation. Lead to chronic poisoning and other serious diseases, causing incalculable damage to human life and health. Therefore, various countries have increasingly strict control over the toxic and harmful pollutants in e-waste, especially heavy metal ions, and have put forward higher and higher requirements for the detection technology of heavy metal content in various media.
  • the detection techniques for heavy metal content in different media in the prior art are roughly divided into three categories: spectroscopic analysis, electrochemical analysis, and biochemical analysis.
  • the instruments used in electrochemical analysis methods are relatively small in size, low in cost, easy to realize miniaturization and integration of detection equipment, flexible and changeable, and have strong adaptability.
  • the anodic stripping voltammetry (ASV) in the electrochemical analysis method is based on the specific oxidation or dissolution peak potential of each metal to perform qualitative and quantitative analysis of metal ions in the solution, which is very suitable for detection Method for trace heavy metals.
  • Traditional ASV uses a rod-shaped three-electrode system for measurement in a beaker.
  • the detection process requires a large amount of sample solution, a long pre-electrolysis time, and poor reproducibility of detection results, which is inconvenient as a solution for rapid on-site detection.
  • a microfluidic chip is a microchannel that is processed on a small substrate material, and other functional units, including a sample delivery unit, a pre-processing unit, a reaction unit, a separation unit, an optical or electrical response detection unit, are integrated into the chip
  • other functional units including a sample delivery unit, a pre-processing unit, a reaction unit, a separation unit, an optical or electrical response detection unit, are integrated into the chip
  • the sample demand and reagent consumption are small, which greatly reduces the environmental protection load of the laboratory and the risk of secondary pollution, which is in line with the development trend of modern analytical technology.
  • the microfluidic chip used for ASV heavy metal ion detection in the prior art usually includes a microfluidic layer and a sensor layer with electrodes required for electrochemical analysis.
  • the microfluidic layer has microchannels as a channel for the circulation of the solution to be tested. In the fluid working area, there are matching electrodes in the sensor layer. In actual use, the sensor layer is combined in the microfluidic layer to perform the detection process.
  • the microchannel is designed in a thin layer form, which can reduce the amount of sample test solution and improve the efficiency of the test solution and the reaction surface. Accordingly, the electrode is designed in a flat form to match the thin layered microchannel.
  • the existing microfluidic chip for ASV heavy metal ion detection has the advantages of small size, convenient carrying and high detection efficiency on the basis of ensuring detection sensitivity and stability. It can realize rapid in-situ detection on site and lead the future ASV heavy metal ion detection Development trend. On the basis of the existing microfluidic chip for ASV heavy metal ion detection, how to further improve the detection performance has become a technical problem that needs to be solved.
  • the invention provides an electrode-modified heavy metal ion microfluidic detection chip and a preparation method.
  • the porous nano-NiMn 2 O 4 is used to modify the bare carbon working electrode in the all-solid planar electrode, which effectively improves the microfluidic chip's resistance to trace amounts of lead and cadmium. Sensitivity of detection.
  • an embodiment of the present invention provides an electrode-modified heavy metal ion microfluidic detection chip, which includes a microfluidic module and a three-electrode sensor, wherein:
  • the microfluidic module contains a microchannel inside, and both ends of the microchannel are provided with a liquid inlet pipe and a liquid outlet pipe communicating with the outside;
  • the three-electrode sensor includes three all-solid-state planes arranged on a card-shaped bottom plate The electrodes are respectively a working electrode, an auxiliary electrode and a reference electrode.
  • One end of the three-electrode sensor is an interface area, and the three all-solid-state planar electrode lead ends are arranged as contact pins in the interface area;
  • the microfluidic control The module is provided with a sensor slot matching the three-electrode sensor at the bottom of the microchannel; when the three-electrode sensor is inserted into the sensor slot, the three all-solid planar electrodes communicate with the microchannel,
  • the three-electrode sensor is assembled with the microfluidic module by inserting the sensor slot, which is a detachable design; the interface area remains outside the sensor slot, and the contact pins of each electrode in the interface area are connected by external connectors during detection , Apply a voltage to the electrode while detecting the current of the electrode loop;
  • the microfluidic module is a 3D printed transparent flexible device, and the microchannel, the liquid inlet pipe, the liquid outlet pipe and the sensor inside it
  • the slot is integrally formed with the printing of the microfluidic module;
  • the working electrode is
  • the microchannel is a saddle-shaped thin layer, and the liquid inlet pipe and the liquid outlet pipe are respectively connected to the two saddle-shaped ends of the microchannel and extend along the direction tangent to the ends. extend.
  • the liquid inlet pipe and the liquid outlet pipe respectively have a liquid inlet pipe port and a liquid outlet pipe port protruding from the surface of the microfluidic module to facilitate connection with an external fluid pipeline.
  • the interface area and the contact pins are set according to the USB specification, so that the interface area can be directly inserted into the USB interface, and the contact pins can be connected to the pins of the USB interface correspondingly;
  • the USB interface has four pins arranged in parallel.
  • the embodiment of the present invention also provides a method for preparing the above-mentioned electrode-modified heavy metal ion microfluidic detection chip, which includes the following steps:
  • microfluidic module production The microfluidic module is made by 3D printing polymer jetting process.
  • the internal microchannel, inlet tube, outlet tube and sensor slot are integrated with the microfluidic module printing, and the printing material Vero Clear photosensitive resin;
  • Three-electrode sensor production The three-electrode sensor matching the microfluidic module is made by screen printing.
  • the insulating card is used as the base plate, and the three electrodes are printed on the base plate in layers, including working electrode, auxiliary electrode and reference electrode.
  • the three electrode lead ends are arranged at one end of the bottom plate to form an interface area; the surface of the working electrode is modified with porous nano-NiMn 2 O 4;
  • Microfluidic detection chip assembly Insert one end of the non-interface area of the three-electrode sensor into the sensor slot, connect the three-electrode sensor with the microchannel, and close the three-electrode sensor with the sensor slot, leaving the interface area in the sensor slot It is used for external connection, that is, the microfluidic module and the three-electrode sensor are assembled into a microfluidic detection chip.
  • the bottom plate is made of flexible PVC material, and the step of layered printing of the three electrodes includes:
  • Insulating ink is printed and covered in other areas of the bottom plate other than the three electrodes and the lead area.
  • the step of modifying the surface of the working electrode with porous nano-NiMn 2 O 4 includes:
  • the specific steps include:
  • reaction product is washed at least 5 times with distilled water and then dried;
  • the specific steps include:
  • the above-mentioned technical scheme of the present invention is based on microfluidic technology, combining a 3D integrated printing microfluidic module with microchannels and a screen-printed all-solid planar electrode to form a heavy metal ion microfluidic detection chip, which is used for ASV method detection solution
  • the modified with porous nano-NiMn 2 O 4 has the following beneficial effects: the impedance of the working electrode does not increase much, and good reversibility is maintained.
  • the detection chip has a good linear response to lead and cadmium, and the detection sensitivity of trace lead and cadmium is significantly improved, which can be increased by more than 30% and 50%, respectively, so that the detection limit is as low as the original bare carbon Half of the working electrode time, effectively enhancing the heavy metal ion detection performance of the microfluidic detection chip.
  • FIG. 1 is a schematic diagram of the structure of a heavy metal ion microfluidic detection chip provided by an embodiment of the present invention
  • FIG. 2 is a schematic diagram of the internal structure of a microfluidic module provided by an embodiment of the present invention.
  • FIG. 3 is a schematic structural diagram of a three-electrode sensor provided by an embodiment of the present invention.
  • FIG. 4 is a schematic diagram of assembling a three-electrode sensor and a microfluidic module according to an embodiment of the present invention
  • Figure 5 is a schematic diagram of ASV detection principle
  • FIG. 6 is a schematic diagram of the matching connection between the interface area of the three-electrode sensor and the USB connector provided by an embodiment of the present invention
  • FIG. 7 is a flowchart of steps of a method for preparing a heavy metal ion microfluidic detection chip provided by an embodiment of the present invention.
  • FIG. 8 is a flowchart of manufacturing steps of a three-electrode sensor according to an embodiment of the present invention.
  • FIG. 9 is a schematic diagram of layered printing of three electrodes by a screen printing process according to an embodiment of the present invention.
  • 1-microfluidic module 10-microchannel; 11-sensor slot; 12-liquid inlet tube; 121-liquid inlet tube; 13-liquid outlet tube; 131-liquid outlet tube; 2-three-electrode sensor; 20-bottom plate; 21-working electrode; 22-auxiliary electrode; 23-reference electrode; 24-interface area; 240-contact pin; 3-USB interface.
  • the present invention addresses the technical problem that the detection performance of the microfluidic chip used for ASV heavy metal ion detection in the prior art needs to be further improved.
  • This embodiment provides an electrode-modified heavy metal ion microfluidic detection chip as shown in FIG.
  • the microfluidic detection chip includes a microfluidic module 1 and a three-electrode sensor 2 that are matched with each other as shown in Figs. 2 to 4, and the specific structure is as follows:
  • the microfluidic module 1 contains a microchannel 10 inside.
  • the two ends of the microchannel 10 are provided with a liquid inlet tube 12 and a liquid outlet tube 13 communicating with the outside;
  • the microfluidic module 1 is provided at the bottom of the microchannel 10
  • the microfluidic module 1 is a transparent flexible device made by 3D printing, with a transparent detection window, which is convenient for monitoring the flow state of the liquid in the microchannel and the electrode surface during the detection process
  • the flexible material also facilitates the close cooperation between the three-electrode sensor 2 and the sensor socket 11;
  • the microchannel 10, the liquid inlet tube 12, the liquid outlet tube 13 and the sensor socket 11 inside the microfluidic module 1 follow
  • the printing of the microfluidic module 1 is integrally formed, and the entire microfluidic module 1 and its internal structure are seamlessly integrated, which avoids the risk of liquid leakage caused by the splicing of multiple components.
  • the three-electrode sensor 2 includes three all-solid-state planar electrodes arranged on the card-shaped base plate 20, namely, a working electrode 21, an auxiliary electrode 22, and a reference electrode 23.
  • One end of the three-electrode sensor 2 is an interface area 24.
  • the three all-solid planar electrode lead ends are arranged as contact pins 240 in the interface area 24;
  • the three-electrode sensor 2 when the three-electrode sensor 2 is inserted into the sensor slot 11, three all-solid planar electrodes are connected to the microchannel 10, and the three-electrode sensor 2 and the microfluidic module 1 can form the microfluidic detection chip ;
  • the three-electrode sensor 2 is a detachable design and can be freely plugged and unplugged in the sensor slot 11.
  • the gap between the sensor slot 11 and the sensor slot 11 can be leaked, and different sensors can be replaced by plugging and unplugging to meet the detection requirements of multiple samples, avoiding cross-contamination between samples; the interface area 24 remains outside the sensor slot 11, and the detection is performed by
  • the external connector is connected to the contact pin 240 of each electrode of the interface area 24, and can apply voltage to the electrode and can also detect the current of the electrode circuit.
  • the working electrode 21 requires a small resistance and a larger surface area. Therefore, the most conductive Ag is selected for the bottom layer, and a layer of nano-carbon is covered on the Ag layer to form a bare carbon working electrode. NiMn 2 O 4 modification.
  • the microfluidic detection chip After the working electrode is modified, the microfluidic detection chip has a better linear response to lead and cadmium, and significantly improves the detection sensitivity to trace amounts of lead and cadmium; the auxiliary electrode requires low resistance and is composed of a bare Ag layer; Electrode 23 is required to have stable potential and is composed of the bottom Ag layer and the Ag/AgCl layer covered on the Ag layer, and the potential is controlled by Ag/AgCl; the surface of the three-electrode sensor 2 is covered with a carbon layer except for the exposed part of the insulating layer.
  • the electrode-modified heavy metal ion microfluidic detection chip provided in the above embodiment is used for ASV heavy metal ion detection.
  • ASV is a very suitable electrochemical analysis method for the detection of trace heavy metals from the perspective of its working process. The detection steps are divided into two processes: reduction pre-electrolysis enrichment and reverse oxidation electrolysis dissolution.
  • ASV heavy metal ions The volt-ampere characteristic curve of the detection process, the vertical axis shows the applied voltage E, and the horizontal axis shows the measured current i; in the detection, the fixed value reduction negative voltage is first applied to the surface of the working electrode, and the reduction potential is higher than this The metal ions of voltage will be reduced to metal elements on the surface of the working electrode and be enriched.
  • the enrichment amount is positively related to the time of applying voltage and the concentration of metal ions.
  • the electrode loop current is measured to obtain the enrichment volts in the positive region of the vertical axis E in Figure 5 Ampere curve; then apply a positive scanning voltage on the working electrode, at this time the enriched metal element will be re-oxidized into ions and dissolved out, record the current and potential, and get the dissolution volt-ampere curve of the negative area of the vertical axis E in Figure 5 From the stripping volt-ampere curve, a peak current i p of ⁇ A or less can be obtained.
  • each metal has a specific oxidation or dissolution peak Potential
  • the size of the peak current i p is proportional to the concentration of the metal ion in the solution to be tested, and the heavy metals in the solution are analyzed qualitatively and quantitatively based on this.
  • test solution add bismuth ion (Bi 3+ ) solution and acidic base solution to the test solution containing heavy metal ions;
  • Assemble the detection platform connect hoses to the inlet and outlet pipes of the microfluidic module; set up a peristaltic pump on the hose connected to the inlet pipe, and communicate with the solution container to be tested; by connecting the outlet pipe The hose is used to drain the waste liquid; the working electrode, reference electrode and auxiliary electrode pins of the three-electrode sensor interface area are respectively connected to the working electrode WE, reference electrode RE, and auxiliary electrode AE leads of the electrochemical workstation;
  • Enrichment A negative voltage is applied between the working electrode and the reference electrode by the electrochemical workstation; the peristaltic pump is turned on and the solution to be tested flows into the microchannel through the liquid inlet tube, and the pre-electrolysis starts under the action of the three electrodes, and the heavy metal ions are reduced to After the elemental metal is enriched on the surface of the working electrode, the waste liquid is discharged; after the pre-electrolysis is completed, the peristaltic pump is turned off and the solution to be tested is allowed to stand still;
  • the electrochemical workstation applies a forward scanning voltage between the working electrode and the reference electrode, and the heavy metals enriched on the working electrode are oxidized into heavy metal ions and dissolved out;
  • Collect voltammetric data record the current and working electrode potential in the working electrode and counter electrode loop during the dissolution process to obtain the dissolution voltammetry curve; obtain the peak current i p of the solution to be tested through the dissolution voltammetry curve, and compare i p with the The peak current of a standard sample with a known concentration is compared and calculated under the same conditions to obtain the concentration of specific heavy metal ions in the solution to be tested.
  • the heavy metal ion microfluidic detection chip provided in the above embodiment can be optimized for ASV detection, as follows:
  • the volume of the microchannel as the fluid working area should be as small as possible, and the fluid working area should be designed as a thin layer to help improve the efficiency of the three electrodes on the solution flowing through it. Therefore, it is a better implementation method
  • the microchannel 10 should be processed into a thin layer.
  • the two-dimensional shape of the microchannel 10 can be selected from saddle, rectangular, circular, elliptical and other shapes. Rectangle and saddle are the most commonly used. It is proved by theoretical analysis and experiments.
  • the saddle-shaped thin-layer microchannel 10 as shown in Fig. 2 is the best;
  • connection positions and nozzle directions of the liquid inlet tube 12 and the liquid outlet tube 13 and the microchannel 10 to facilitate the smooth flow of the solution to be tested through the microchannel 10, as shown in Figure 2, when the microchannel When the channel 10 is a saddle-shaped thin layer, the liquid inlet tube 12 and the liquid outlet tube 13 are respectively connected to the two ends of the saddle shape of the microchannel 10 and extend in a direction tangent to the ends;
  • the liquid inlet pipe 12 and the liquid outlet pipe 13 are respectively provided with a liquid inlet pipe port 121 and a liquid outlet protruding from the surface of the microfluidic module 1.
  • the nozzle 131 is used to connect fluid pipes such as hoses.
  • a transparent material is selected to make the microfluidic module 1;
  • the microchannel 10 is a saddle-shaped thin layer, and the liquid inlet tube 12 and the liquid outlet tube 13 are respectively connected to the two saddle-shaped ends of the microchannel 10, and run along the ends of the microchannel 10. The part extends in the tangential direction.
  • the liquid inlet pipe 12 and the liquid outlet pipe 13 respectively have a liquid inlet nozzle 121 and a liquid outlet nozzle 131 protruding from the surface of the microfluidic module 1 to facilitate connection with external fluid pipelines.
  • the microfluidic module 1 is made of a transparent material, so that the microfluidic module 1 has a transparent detection window, which facilitates real-time observation of working conditions during the detection process.
  • the interface area 24 and the contact pins 240 are arranged in accordance with the USB specifications, so that the interface area 24 can be directly inserted into a standard USB interface, and the contact pins 240 can be connected to the pins of the standard USB interface correspondingly;
  • the USB interface has four pins arranged in parallel.
  • the interface area 24 is docked with the USB interface, only three contact pins 240 need to be in contact with any three of the four pins in the standard USB interface in sequence, such as As shown in FIG. 6, the three contact pins 240 respectively correspond to the three adjacent pins on the right side of the USB interface 3, which can be freely designed according to actual needs in actual work.
  • the present invention also provides a method for preparing the above heavy metal ion microfluidic detection chip.
  • the process flow is shown in Fig. 7 and includes:
  • Microfluidic module production 3D printed polymer jetting process is used to produce microfluidic module.
  • the internal microchannel, inlet tube, outlet tube and sensor slot are integrated with the microfluidic module printing, and the printing material Vero Clear photosensitive resin;
  • Three-electrode sensor production the three-electrode sensor that matches the microfluidic module is made by screen printing.
  • the insulating card is used as the bottom plate, and three electrodes are printed on the bottom plate in layers, including working electrode, auxiliary electrode and reference electrode.
  • the three electrode lead ends are arranged at one end of the bottom plate to form an interface area; the surface of the working electrode is modified with porous nano-NiMn 2 O 4;
  • Microfluidic detection chip assembly insert one end of the non-interface area of the three-electrode sensor into the sensor slot, connect the three-electrode sensor with the microchannel, and close the three-electrode sensor with the sensor slot, leaving the interface area in the sensor slot It is used for external connection, that is, the microfluidic module and the three-electrode sensor are assembled into a microfluidic detection chip.
  • step S1 the 3D printing of the microfluidic module can use an Eden260vs 3D printer, using a polymer jet (PolyJet) process, in the gloss printing mode, a microfluidic module with high transparency and certain flexibility can be printed;
  • PolyJet is At present, the leading 3D printing technology works similarly to inkjet printers.
  • the nozzle array ejects photopolymer micro-droplets, which are simultaneously cured by the ultraviolet light source installed on the nozzle to obtain a printing layer; then the workbench drops a layer Make the next layer thick.
  • PolyJet molded parts have a very high precision, with a plane accuracy of 40 ⁇ m and a thickness of 16 ⁇ m.
  • Very complex and detailed models can be made to meet the accuracy requirements of most microfluidic chips; when printing, the main material of the microfluidic module It is a Vero Clear photosensitive resin.
  • the internal structure position is first printed and molded with a supporting material along with the body of the microfluidic module, and then the supporting material is removed to obtain the internal structure of the microfluidic module; the supporting material is a water-soluble FullCure707 Best, after the printing is completed, the printed piece is removed from the supporting material in the water-soluble supporting removal melting box.
  • step S2 the three electrodes are printed layer by layer on the bottom plate using a screen printing process to obtain a solid-state planar three-electrode sensor unit.
  • the bottom plate of the screen-printed electrodes can be made of flexible materials (such as PVC, PET, PC, etc.) or rigid materials (glass, ceramics, etc.).
  • flexible PVC material bottom plate to make flat electrode flexible material bottom plate can ensure that the electrode can still work normally when the bending radius of curvature is small
  • Figure 8 shows an example of step S2 in which the three electrodes are printed in layers by a screen printing process and the surface of the working electrode is modified with NiMn 2 O 4 porous nanomaterials.
  • the specific steps include:
  • Insulating ink is printed on other areas of the bottom plate other than the three electrodes and the lead area, and the insulating layer pattern is as shown in the V layer in FIG. 9;
  • step S25 Preparation of porous nano-NiMn 2 O 4 materials.
  • the specific steps of an example of this step S25 include:
  • Modifying the working electrode fixing the porous nano-NiMn 2 O 4 on the surface of the working electrode with Nafion to modify the working electrode; the steps of a specific example of this step include:
  • the working electrode on the three-electrode sensor was modified with porous nano-NiMn 2 O 4.
  • the modified working electrode and the bare carbon working electrode were used in the detection of heavy metal ions in the microfluidic detection chip. It is found that after using Nafion to modify the porous nano-NiMn 2 O 4 powder on the surface of the flat electrode, the impedance of the working electrode does not increase much, and it maintains good reversibility. It has a good linear response and sensitivity to trace amounts of lead and cadmium. They are increased by 30% and 50% respectively, and the detection limit is as low as half of that of the bare carbon electrode, which significantly improves the performance of the microfluidic detection chip.

Abstract

一种电极修饰的重金属离子微流控检测芯片，包括微流控模块（1）和三电极传感器（2），其中微流控模块（1）由3D打印一体成型，内部有微通道（10）和传感器插槽（11），三电极传感器（2）包括由印制于卡片状底板（20）上的三个电极（21，22，23），其中工作电极（21）为经多孔纳米NiMn2O4修饰的裸碳电极，将三电极传感器（2）插入与其匹配的传感器插槽（11）组成该微流控检测芯片。

Description

电极修饰的重金属离子微流控检测芯片及制备方法 技术领域
本发明属于电化学检测技术领域，特别涉及一种电极修饰的重金属离子微流控检测芯片。本发明还提供了所述微流控芯片的制备方法。
背景技术
随着互联网产业化、工业智能化的发展，电子电气产品数量呈爆发性增长，人类在享受现代科学技术和电子商务带来的全新生活方式的同时，也面临大量电子垃圾对生存环境造成的日渐增长的威胁。重金属为电子垃圾中最主要的污染成分之一，广泛存在于电子电气产品中，若原料、产品或废弃物未能得到良好管控，重金属会直接进入土壤、水体和大气，造成直接污染，也可通过相互迁移于不同环境之间造成间接污染。由于重金属不可降解，能通过食物链迁移、富集最终被人体摄入并在脏器中积累，且摄入的重金属难以排出体外，人体内的重金属极易与蛋白和酶等结合致其失活，导致慢性中毒及其他严重病变，对人类的生命健康造成难以估量的损害。因此，各国对电子垃圾中的有毒有害污染物，特别是重金属离子的管控日益严格，对各种介质中重金属含量的检测技术也提出了越来越高的要求。
现有技术中不同介质中重金属含量的检测技术大致分为三大类：光谱分析法、电化学分析法及生化分析法。其中，电化学分析法所用仪器体积相对较小，成本低廉，检测设备易于实现微型化和集成化，灵活多变，适应性强，近年来逐渐成为分析仪器研究的重点。电化学分析法中的阳极溶出伏安法(Anodic Stripping Voltammetry，ASV)基于每种金属都有特定的氧化或溶出峰电位对溶液中的金属离子进行定性和定量分析，是一种非常适合作为检测痕量重金属的方法。传统ASV使用棒状三电极体系在烧杯中进行测定，检测过程对试样溶液需求量大、预电解时间长，检测结果重现性较差，不便作为现场快速检测的解决方案。
近年来，微流控芯片技术的发展为ASV的发展开辟了新方向。微流控芯片是在一块很小的基体材料上加工出微通道，并且将其他功能单元，包括样品输送单元、前处理单元、反应单元、分离单元、光学或电学响应检测单元，集成于芯片之上，由于其微型化的优点，样品需求量和试剂消耗量均很小，大大降低了实验室的环保负荷和二次污染的风险，非常契合现代分析技术的发展趋势。现有技术中用于ASV重金属离子检测的微流控芯片通常包含微流控层和带有电化学分析所需电极的传感器层，微流控层中具有微通道，作为供待测溶液流通的流体工作区，传感器层中具有匹配的电极，实际使用时将传感器层组合在微流控层中进行检测流程。微通道设计为薄层形式，可减少样品试液的用量，同时提高试液与反应面的作用效率，相应地将电极设计为平面形式，与薄层状的微通道匹配。现有的ASV重金属离子检测的微流控芯片在保证检测灵敏度和稳定性的基础上，具有体积小，方便携带，检测效率高的优点，可实现现场快速原位检测，引领未来ASV重金属离子检测的发展趋势。在现有的用于ASV重金属离子检测的微流控芯片的基础上，如何进一步提升检测性能，成为需要解决的技术问题。
发明内容
本发明提供一种电极修饰的重金属离子微流控检测芯片及制备方法，采用多孔纳米NiMn 2O 4修饰全固态平面电极中的裸碳工作电极，有效提升微流控芯片对痕量铅和镉检测的灵敏度。
为解决上述技术问题，本发明的实施例提供一种电极修饰的重金属离子微流控检测芯片，包括微流控模块和三电极传感器，其中：
所述微流控模块内部包含微通道，所述微通道的两端设置有与外部连通的进液管和出液管；所述三电极传感器包括设置于卡片状底板上的三个全固态平面电极，分别为工作电极、辅助电极和参比电极，所述三电极传感器一端为接口区，所述三个全固态平面电极引线末端作为触脚排列在所述接口区内；所述微流控模块在所述微通道底部设置有匹配所述三电极传感器的传感器插槽；当所述三电极传感器插入所述传感器插槽后，所述三个全固态平面电极与所述微通道实现连通，三电极传感器通过插入传感器插槽与微流控模块组装在一起， 为可拆卸设计；所述接口区留在所述传感器插槽之外，检测时由外部接头连接接口区的各电极的触脚，对电极施加电压，同时检测电极回路的电流；所述微流控模块为3D打印的透明柔性器件，其内部的所述微通道、所述进液管、所述出液管和所述传感器插槽随所述微流控模块的打印一体成型；所述工作电极为裸碳电极，表面以多孔纳米NiMn 2O 4修饰；所述辅助电极为Ag电极；所述参比电极为Ag/AgCl电极。
作为微流控模块的优选，所述微通道为鞍形薄层，所述进液管和出液管分别连接在所述微通道的两个鞍形端部，并沿与端部相切方向延伸。
优选地，所述进液管和所述出液管分别具有凸出所述微流控模块表面的进液管口和出液管口，便于与外部流体管道连接。
作为三电极传感器的优选，所述接口区和所述触脚按照USB规格设置，使所述接口区可直接插入USB接口，且所述触脚可与USB接口的引脚对应连通；因标准的USB接口具有平行排列的四个引脚，当所述接口区与USB接口对接时，只需三个触脚与标准USB接口内任意三个引脚接触即可，可根据实际需求自由选择。
本发明实施例还提供了上述电极修饰的重金属离子微流控检测芯片的制备方法，包括以下步骤：
1.微流控模块制作：采用3D打印的聚合物喷射工艺制作微流控模块，其内部的微通道、进液管、出液管和传感器插槽随微流控模块打印一体成型，打印材料为Vero Clear光敏树脂；
2.三电极传感器制作：采用丝网印刷方式制作匹配微流控模块的三电极传感器，以绝缘卡片为底板，在底板上分层印刷三电极，包括工作电极、辅助电极和参比电极，所述三电极引线末端排列在底板一端形成接口区；再用多孔纳米NiMn 2O 4对工作电极表面进行修饰；
3.微流控检测芯片组装：将三电极传感器非接口区一端插入传感器插槽，使所述三电极与微通道连通，三电极传感器与传感器插槽密合，将接口区留在传感器插槽之外用于外部连接，即将微流控模块和三电极传感器组装成微流控检测芯片。
作为步骤2三电极传感器制作的优选，所述底板采用柔性PVC材料，所 述分层印刷三电极的步骤包括：
2.1.在底板上印刷所述三电极及引线的底层Ag层；
2.2.在所述参比电极的Ag层上印刷Ag/AgCl层；
2.3.在所述三电极的引线及所述工作电极的Ag层上印刷碳层；
2.4.在所述底板的所述三电极和引线区之外的其他区域印刷覆盖绝缘油墨。
作为步骤2三电极传感器制作的优选，所述用多孔纳米NiMn 2O 4对工作电极表面进行修饰的步骤包括：
2.5.制备多孔纳米NiMn 2O 4；
2.6.修饰工作电极：用Nafion将多孔纳米NiMn 2O 4固定在所述工作电极的表面以修饰所述工作电极。
作为步骤2.5制备多孔纳米NiMn 2O 4的优选，其具体步骤包括：
2.5.1.将MnCl 2·6H 2O 20mmol/L，NiCl 2·6H 2O 40mmol/L，Mn(NH 2) 2120mmol/L和NH 4F 0.1g溶解在5mL乙醇和30mL去离子水中，剧烈搅拌30min；
2.5.2.待溶液自然冷却到室温后，用蒸馏水清洗反应产物至少5次后进行干燥；
2.5.3.将反应产物在2℃/min的管式炉中进行空气退火，并在350℃下保持3h，即制得多孔纳米NiMn 2O 4粉末。
作为步骤2.6修饰工作电极的优选，其具体步骤包括：
2.6.1.将多孔纳米NiMn 2O 4粉末加入甲醇溶液中，超声使其分散均匀；
2.6.2.移取5μL溶液滴涂于工作电极的碳层表面，于室温晾干；
2.6.3.移取5μL质量百分比为0.5％的Nafion溶液涂敷在滴涂了多孔纳米NiMn 2O 4的工作电极表面，室温干燥3h，即制得多孔纳米NiMn 2O 4修饰的工作电极。
本发明上述技术方案基于微流控技术，将3D一体成型打印的具有微通道的微流控模块和丝网印刷的全固态平面电极配合组成重金属离子微流控检测芯片，用于ASV法检测溶液中的重金属离子浓度，并在现有全固态平面电极裸碳工作电极的基础上，用多孔纳米NiMn 2O 4进行修饰，其有益效果为：在工作电极阻抗增加不大，保持了良好可逆性的前提下，使检测芯片对铅和镉具 有良好的线性响应，显著提升对痕量铅和镉的检测灵敏度，分别可提升30％和50％以上，使检出限低至使用原有裸碳工作电极时的一半，有效增强微流控检测芯片的重金属离子检测性能。
附图说明
图1为本发明实施例提供的重金属离子微流控检测芯片结构示意图；
图2为本发明实施例提供的微流控模块的内部结构示意图；
图3为本发明实施例提供的三电极传感器的结构示意图；
图4为本发明实施例提供的三电极传感器与微流控模块组装示意图；
图5为ASV检测原理示意图；
图6为本发明实施例提供的三电极传感器接口区与USB接头匹配连接示意图；
图7为本发明实施例提供的重金属离子微流控检测芯片的制备方法的步骤流程图；
图8为本发明实施例提供的三电极传感器制作步骤流程图；
图9为本发明实施例丝网印刷工艺分层印刷三电极的示意图。
[主要元件符号说明]
1-微流控模块；10-微通道；11-传感器插槽；12-进液管；121-进液管口；13-出液管；131-出液管口；2-三电极传感器；20-底板；21-工作电极；22-辅助电极；23-参比电极；24-接口区；240-触脚；3-USB接口。
具体实施方式
为使本发明要解决的技术问题、技术方案和优点更加清楚，下面将结合附图及具体实施例进行详细描述。
本发明针对现有技术用于ASV重金属离子检测的微流控芯片的检测性能有待进一步提升的技术问题，本实施例提供如图1所示的电极修饰的重金属离子微流控检测芯片，所述微流控检测芯片包括图2至图4所示相互匹配的微流控模块1和三电极传感器2，具体结构如下：
如图2所示，微流控模块1内部包含微通道10，微通道10的两端设置有 与外部连通的进液管12和出液管13；微流控模块1在微通道10底部设置有匹配三电极传感器2的传感器插槽11；微流控模块1为由3D打印制作出的透明柔性器件，具有透明的检测视窗，便于在检测过程中监控微通道中液体的流动状态及电极表面的反应情况，同时柔性的材质也便于三电极传感器2和传感器插槽11实现紧密配合；微流控模块1内部的微通道10、进液管12、出液管13和传感器插槽11均随微流控模块1的打印一体成型，整个微流控模块1及其内部结构为无缝整体，避免了多个部件的拼接造成的漏液风险。
如图3所示，三电极传感器2包括设置于卡片状底板20上的三个全固态平面电极，分别为工作电极21、辅助电极22和参比电极23，三电极传感器2一端为接口区24，三个全固态平面电极引线末端作为触脚240排列在接口区24内；
如图4所示，当三电极传感器2插入传感器插槽11，三个全固态平面电极与微通道10实现连通，三电极传感器2和微流控模块1即可组成所述微流控检测芯片；三电极传感器2为可拆卸设计，可在传感器插槽11中自由插拔，只需保证三电极传感器2与传感器插槽11密合，使微通道10中的液体不会从三电极传感器2和传感器插槽11的间隙泄漏即可，通过插拔可更换不同的传感器以满足多个样本的检测需求，避免样本间的交叉污染；接口区24留在传感器插槽11之外，检测时由外部接头连接接口区24的各电极的触脚240，可对电极施加电压，也可检测电极回路的电流。
三电极传感器2中，工作电极21要求电阻较小，比表面大，因此底层选择导电性最强的Ag，在Ag层上覆盖一层纳米碳，形成裸碳工作电极，其表面再以多孔纳米NiMn 2O 4修饰。工作电极经修饰后可使微流控检测芯片对铅和镉具有更好的线性响应，显著提升对痕量铅和镉的检测灵敏度；辅助电极要求电阻小，以裸露的Ag层构成；参比电极23要求电位稳定，由底层的Ag层和Ag层上覆盖的Ag/AgCl层构成，由Ag/AgCl控制电位；三电极传感器2表面除绝缘层暴露部分外，其它部分均用碳层覆盖。
上述实施例提供的电极修饰的重金属离子微流控检测芯片用于ASV重金属离子检测。ASV从工作过程看是一种非常适合作为检测痕量重金属的电化学分析方法，其检测步骤分为还原预电解富集和反向氧化电解溶出两个过程， 如图5所示为ASV重金属离子检测过程的伏安特性曲线，其纵轴所示为施加的电压E，横轴所示为测得的电流i；检测时先将定值还原负电压施加于工作电极表面，还原电位高于该电压的金属离子将在工作电极表面还原为金属单质而富集，富集量与施加电压的时间和金属离子的浓度成正相关，测量电极回路电流得到图5中纵轴E正区域的富集伏安曲线；然后在工作电极上施加一个正向扫描电压，此时富集的金属单质将重新被氧化成离子而溶出，记录电流与电位，得到图5中纵轴E负区域的溶出伏安曲线，由该溶出伏安曲线可得到μA级或更小的峰值电流i p，若控制所有操作条件(电解质底液、电极、加压参数等)一致，每种金属都有特定的氧化或溶出峰电位，峰值电流i p的大小与待测溶液中该种金属离子的浓度成正比，据此对溶液中重金属进行定性和定量分析。
上述实施例提供的电极修饰的重金属离子微流控检测芯片以ASV方法对溶液中的特定重金属离子进行检测的基本流程为：
1.配制待测溶液：在含有重金属离子的待测溶液中加入铋离子(Bi 3+)溶液和酸性底液；
2.组装检测平台：在微流控模块的进液管和出液管分别连接软管；连接进液管的软管上设置蠕动泵，并与待测溶液容器连通；由连接出液管的软管排放废液；将三电极传感器接口区的工作电极、参比电极和辅助电极引脚分别与电化学工作站的工作电极WE、参比电极RE、辅助电极AE引线对应连接；
3.富集：由电化学工作站在工作电极和参比电极间施加负电压；打开蠕动泵，驱动待测溶液通过进液管流入微通道，在三电极作用下开始预电解，重金属离子还原为金属单质后富集在工作电极表面，排出废液；预电解结束后，关闭蠕动泵，静置待测溶液；
4.溶出：由电化学工作站在工作电极和参比电极间施加由正向扫描电压，工作电极上富集的重金属被氧化为重金属离子溶出；
5.采集伏安数据：记录溶出过程工作电极和对电极回路中的电流与工作电极电位，获得溶出伏安曲线；通过溶出伏安曲线得到待测溶液的峰值电流i p，将i p与已知浓度的标准试样在相同条件下检测得到的峰值电流对比计算，即得待测溶液中特定重金属离子的浓度。
由上述重金属离子微流控检测芯片的工作过程可知，可对上述实施例提供 的重金属离子微流控检测芯片作出适合ASV检测的优化，具体如下：
为减少待测溶液的用量，微通道作为流体工作区其体积应尽量小，流体工作区应设计为薄层形式，以利于提高三电极对流经溶液的作用效率，因此，作为更佳的实施方式，微通道10应加工为一薄层，微通道10二维形状可选择鞍形、矩形、圆形、椭圆形等多种形状，以矩形和鞍形最为常用，通过理论分析和实验证明，以如图2所示的鞍形薄层微通道10为最佳；
进液管12和出液管13与微通道10的连接位置和管口方向也具有多种选择，以有利于待测溶液顺畅地流经微通道10为佳，如图2所示，当微通道10为鞍形薄层时，进液管12和出液管13分别连接在微通道10鞍形的两个端部，并沿与端部相切方向延伸；
为方便进液管12和出液管13连接外部流体管道，如图1所示，进液管12和出液管13分别设置凸出微流控模块1表面的进液管口121和出液管口131，用于连接软管等流体管道。
为便于检测过程中实时监控微通道中液体的流动状态及电极表面的反应情况，选择透明材质制作微流控模块1；
作为微流控模块的优选，所述微通道10为鞍形薄层，所述进液管12和出液管13分别连接在所述微通道10的两个鞍形端部，并沿与端部相切方向延伸。
优选地，所述进液管12和所述出液管13分别具有凸出所述微流控模块1表面的进液管口121和出液管口131，便于与外部流体管道连接。
优选地，所述微流控模块1为透明材质，使微流控模块1具有透明的检测视窗，利于在检测过程中实时观察工作状况。
作为三电极传感器2的优选，将接口区24和触脚240按照USB规格设置，使接口区24可直接插入标准USB接口，且触脚240可与标准USB接口的引脚对应连通；因标准的USB接口具有平行排列的四个引脚，当接口区24与USB接口对接时，只需三个触脚240与标准USB接口内四个引脚中的任意三个引脚依次接触即可，如图6所示，三个触脚240分别与USB接口3右侧的三个相邻的引脚一一对应，实际工作中可根据实际需求自由设计。
为了更好地实现上述技术方案，本发明还提供了上述重金属离子微流控检测芯片的制备方法，其步骤流程如图7所示，包括：
S1.微流控模块制作：采用3D打印的聚合物喷射工艺制作微流控模块，其内部的微通道、进液管、出液管和传感器插槽随微流控模块打印一体成型，打印材料为Vero Clear光敏树脂；
S2.三电极传感器制作：采用丝网印刷方式制作匹配微流控模块的三电极传感器，以绝缘卡片为底板，在底板上分层印刷三电极，包括工作电极、辅助电极和参比电极，所述三电极引线末端排列在底板一端形成接口区；再用多孔纳米NiMn 2O 4对工作电极表面进行修饰；
S3.微流控检测芯片组装：将三电极传感器非接口区一端插入传感器插槽，使所述三电极与微通道连通，三电极传感器与传感器插槽密合，将接口区留在传感器插槽之外用于外部连接，即将微流控模块和三电极传感器组装成微流控检测芯片。
步骤S1中，微流控模块3D打印可采用Eden260vs型3D打印机，采用聚合物喷射(PolyJet)工艺，在高光Glossy打印模式下可打印出高透明度且具有一定柔性的微流控模块器件；PolyJet是目前领先的3D打印技术，工作原理与喷墨打印机类似，喷头阵列喷出的是光敏聚合物微液滴，通过安装在喷头上的紫外光源同步固化，得到一个打印层；随后工作台下降一个层厚进行下一层制作。PolyJet成型的工件精度非常高，平面精度能达40μm，厚度能达16μm，可制作非常复杂且精细的模型，满足绝大多数微流控芯片的精度要求；具体打印时，微流控模块本体材料为Vero Clear光敏树脂，内部结构位置先采用支撑材料随同微流控模块本体一体打印成型，之后去除支撑材料，即可获得微流控模块内留空的内部结构；支撑材料选用水溶性的FullCure707为佳，打印完成后将打印件在水溶性支撑去除溶箱中去除支撑材料。
步骤S2中，采用丝网印刷工艺在底板上分层印制三电极，制得全固态平面三电极传感器单元。丝网印刷电极的底板可选柔性材质(如PVC、PET、PC等)或刚性材质(玻璃、陶瓷等)，为方便丝网印刷电极的批量印刷、切割、存储和携带，作为更加的实施方式，选用柔性PVC材质底板制作平面电极，柔性材料底板可保证在弯曲曲率半径较小时电极仍可正常工作
如图8所示为步骤S2中采用丝网印刷工艺分层印刷三电极及用NiMn 2O 4多孔纳米材料对工作电极表面进行修饰的实例，其具体步骤包括：
S21.在底板上印刷所述三电极及引线的底层Ag层，底板形状参见图9中I层所示，Ag层图形如图9中II层所示；
S22.在所述参比电极的Ag层上印刷Ag/AgCl层，Ag/AgCl层图形如图9中III层所示；
S23.在所述三电极的引线及所述工作电极的Ag层上印刷碳层，碳层图形如图9中IV层所示；
S24.在所述底板的所述三电极和引线区之外的其它区域印刷覆盖绝缘油墨，绝缘层图形如图9中V层所示；
S25.制备多孔纳米NiMn 2O 4材料，该步骤S25一个实例的具体步骤包括：
S251.将MnCl 2·6H 2O 20mmol/L，NiCl 2·6H 2O 40mmol/L，Mn(NH 2) 2120mmol/L和NH 4F 0.1g溶解在5mL乙醇和30mL去离子水中，剧烈搅拌30min；
S252.待溶液自然冷却到室温后，用蒸馏水清洗反应产物至少5次后进行干燥；
S253.将反应产物在2℃/min的管式炉中进行空气退火，并在350℃下保持3h，即制得多孔纳米NiMn 2O 4粉末。
S26.修饰工作电极：用Nafion将多孔纳米NiMn 2O 4固定在所述工作电极的表面以修饰所述工作电极；该步骤一具体实例的步骤包括：
S261.将多孔纳米NiMn 2O 4粉末加入甲醇溶液中，超声使其分散均匀；
S262.移取5μL溶液滴涂于工作电极的碳层表面，于室温晾干；
S263.移取5μL质量百分比为0.5％的Nafion溶液涂敷在滴涂了多孔纳米NiMn 2O 4的工作电极表面，室温干燥3h，即制得多孔纳米NiMn 2O 4修饰的工作电极。
用多孔纳米NiMn 2O 4修饰三电极传感器上的工作电极，通过更换微流控检测芯片中的三电极传感器，考察修饰后的工作电极与裸碳工作电极在微流控检测芯片重金属离子检测时的性能差异，发现采用Nafion将多孔纳米NiMn 2O 4粉末修饰于平面电极表面后，工作电极阻抗增加不大，保持了良好的可逆性，对痕量铅和镉具有良好的线性性响应，灵敏度分别提升了30％和50％以上，检出限低至裸碳电极的一半，明显地提升了微流控检测芯片的性能。
对于上述的本发明的实施例，方案中公知的具体结构及特性等常识未作过 多描述；各实施例采用递进的方式描述，各实施例中所涉及到的技术特征在彼此之间不构成冲突的前提下可以相互组合，各实施例之间相同相似部分互相参见即可。
在本发明的描述中，术语“上”、“下”、“底”等指示的方位或位置关系为基于附图所示的方位或位置关系，仅是为了便于描述本发明和简化描述，而不是指示或暗示所指的装置或元件必须具有特定的方位、以特定的方位构造和操作，不应理解为对本发明的限制。
以上实施例仅用以说明本发明的技术方案而非对其限制，尽管参照上述实施例对本发明进行了详细的说明，所属领域的普通技术人员依然可以对本发明的具体实施方式进行修改或者等同替换，这些未脱离本发明精神和范围的任何修改或者等同替换，均在申请待批的本发明的权利要求保护范围之内。

Claims (9)

  1. 一种电极修饰的重金属离子微流控检测芯片，包括微流控模块(1)和三电极传感器(2)，其中：
    所述微流控模块(1)内部包含微通道(10)，所述微通道(10)的两端设置有与外部连通的进液管(12)和出液管(13)；所述三电极传感器(2)包括设置于卡片状底板(20)上的三个全固态平面电极，分别为工作电极(21)、辅助电极(22)和参比电极(23)，所述三电极传感器(2)一端为接口区(24)，所述三个全固态平面电极引线末端的触脚(240)排列在所述接口区(24)内；所述微流控模块(1)在所述微通道(10)底部设置有匹配所述三电极传感器(2)的传感器插槽(11)；当所述三电极传感器(2)插入所述传感器插槽(11)后，所述三个全固态平面电极与所述微通道(10)实现连通，所述接口区(24)留在所述传感器插槽(11)之外；其特征在于：
    所述微流控模块(1)为3D打印的透明柔性器件，其内部的所述微通道(10)、所述进液管(12)、所述出液管(13)和所述传感器插槽(11)随所述微流控模块(1)的打印一体成型；所述工作电极(21)为裸碳电极，表面以多孔纳米NiMn 2O 4修饰；所述辅助电极(22)为Ag电极；所述参比电极(23)为Ag/AgCl电极。
  2. 根据权利要求1所述的微流控检测芯片，其特征在于，所述微通道(10)为鞍形薄层，所述进液管(12)和出液管(13)分别连接在所述微通道(10)的两个鞍形端部，并沿与端部相切方向延伸。
  3. 根据权利要求1所述的微流控检测芯片，其特征在于，所述进液管(12)和所述出液管(13)分别具有凸出所述微流控模块(1)表面的进液管口(121)和出液管口(131)。
  4. 根据权利要求1至3任一项所述的微流控检测芯片，其特征在于，所述接口区(24)和所述触脚(240)按照USB规格设置，使所述接口区(24)可直接插入USB接口(3)，且所述触脚(240)可 与USB接口(3)的引脚对应连通。
  5. 权利要求1所述的电极修饰的重金属离子微流控检测芯片的制备方法，其特征在于，包括以下步骤：
    微流控模块制作：采用3D打印的聚合物喷射工艺制作微流控模块，其内部的微通道、进液管、出液管和传感器插槽随微流控模块打印一体成型，打印材料为Vero Clear光敏树脂；
    三电极传感器制作：采用丝网印刷方式制作匹配微流控模块的三电极传感器，以绝缘卡片为底板，在底板上分层印刷三电极，包括工作电极、辅助电极和参比电极，所述三电极引线末端排列在所述底板一端形成接口区；再用多孔纳米NiMn 2O 4对工作电极表面进行修饰；
    微流控检测芯片组装：将三电极传感器非接口区一端插入传感器插槽，使所述三电极与微通道连通，三电极传感器与传感器插槽密合，将接口区留在传感器插槽之外用于外部连接，即将微流控模块和三电极传感器组装成微流控检测芯片。
  6. 根据权利要求5所述的制备方法，其特征在于，所述三电极传感器制作步骤中，所述底板采用柔性PVC材料，所述分层印刷三电极的步骤包括：
    在底板上印刷所述三电极及引线的底层Ag层；
    在所述参比电极的Ag层上印刷Ag/AgCl层；
    在所述三电极的引线及所述工作电极的Ag层上印刷碳层；
    在所述底板的所述三电极和引线区之外的其他区域印刷覆盖绝缘油墨。
  7. 根据权利要求5所述的制备方法，其特征在于，所述三电极传感器制作步骤中，所述用多孔纳米NiMn 2O 4对工作电极表面进行修饰的步骤包括：
    制备多孔纳米NiMn 2O 4；
    修饰工作电极，即用Nafion将多孔纳米NiMn 2O 4固定在所述工作电极的表面以修饰所述工作电极。
  8. 根据权利要求7所述的制备方法，其特征在于，所述制备多 孔纳米NiMn 2O 4的步骤包括：
    将MnCl 2·6H 2O 20mmol/L，NiCl 2·6H 2O 40mmol/L，Mn(NH 2) 2120mmol/L和NH 4F 0.1g溶解在5mL乙醇和30mL去离子水中，剧烈搅拌30min；待溶液自然冷却到室温后，用蒸馏水清洗反应产物至少5次后进行干燥；将反应产物在2℃/min的管式炉中进行空气退火，并在350℃下保持3h，制得多孔纳米NiMn 2O 4粉末。
  9. 根据权利要求7所述的制备方法，其特征在于，所述修饰工作电极的步骤包括：
    将多孔纳米NiMn 2O 4粉末加入甲醇溶液中，超声使其分散均匀；
    移取5μL溶液滴涂于工作电极的碳层表面，于室温晾干；
    移取5μL质量百分比为0.5％的Nafion溶液涂敷在滴涂了多孔纳米NiMn 2O 4的工作电极表面，室温干燥3h，即制得多孔纳米NiMn 2O 4修饰的工作电极。
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