CN116223596A - Automatic soil nutrient detection device based on digital microfluidic control - Google Patents

Automatic soil nutrient detection device based on digital microfluidic control Download PDF

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CN116223596A
CN116223596A CN202211668141.1A CN202211668141A CN116223596A CN 116223596 A CN116223596 A CN 116223596A CN 202211668141 A CN202211668141 A CN 202211668141A CN 116223596 A CN116223596 A CN 116223596A
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digital microfluidic
soil
liquid
detection device
digital
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陈翔宇
王儒敬
夏智豪
张俊卿
洪炎
常永嘉
刘洋
陈江宁
陆勤雯
肖家浩
苏阳阳
李梦雅
张家宝
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Hefei Intelligent Agriculture Collaborative Innovation Research Institute Of China Science And Technology
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Hefei Intelligent Agriculture Collaborative Innovation Research Institute Of China Science And Technology
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • 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
    • G01N27/416—Systems
    • G01N27/447—Systems using electrophoresis
    • G01N27/44756—Apparatus specially adapted therefor
    • G01N27/44791—Microapparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
    • B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
    • B01L3/50—Containers for the purpose of retaining a material to be analysed, e.g. test tubes
    • B01L3/502—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures
    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N35/00—Automatic analysis not limited to methods or materials provided for in any single one of groups G01N1/00 - G01N33/00; Handling materials therefor
    • G01N35/00584—Control arrangements for automatic analysers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A40/00—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production
    • Y02A40/10—Adaptation technologies in agriculture, forestry, livestock or agroalimentary production in agriculture

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Abstract

The invention discloses a digital microfluidic-based automatic soil nutrient detection device, which comprises a capillary electrophoresis analyzer, a digital microfluidic platform, a microfluidic pump, a matrix electrode array and a matrix electrode control module, wherein the capillary electrophoresis analyzer is arranged on the capillary electrophoresis analyzer; firstly, carrying out pretreatment on soil sample liquid through filter paper, then separating impurities again through a solid-liquid extractor, and then controlling liquid drops to enter a digital microfluidic platform through a microfluidic pump; the matrix electrode control module controls the flow of liquid drops by controlling the matrix electrode array, the capillary electrophoresis analyzer detects the liquid drops reaching the designated position, and the detection result is displayed by a computer. According to the invention, through capillary electrophoresis analysis (CE analysis), nutrient elements such as nitrogen, phosphorus, potassium and the like in the soil can be rapidly determined through an electrophoresis chart. CE analysis already has a certain market share in the modern agricultural inspection market. The soil detection method has the advantages of less sampling, high detection efficiency, higher detection sensitivity and the like.

Description

Automatic soil nutrient detection device based on digital microfluidic control
Technical Field
The invention relates to the technical field of agricultural detection, in particular to a digital microfluidic-based automatic soil nutrient detection device.
Background
In modern agricultural production, soil is one of important carriers in the breeding industry, and it is important to know the fertility degree of the soil. For barren soil, a breeder can fertilize according to the actual condition of crops; the fertilizer is applied to the fertile soil with little or no fertilizer, so that the soil resource can be fully utilized, the environmental pollution is reduced, and the yield of agricultural products is improved. Therefore, only if the nutrients of the soil are sufficiently detected, targeted fertilization measures can be carried out during planting, so that crops grow more vigorously.
The fertilizer is polluted and overfertilized together with the fertilizer since the birth of the fertilizer. Blind fertilization not only causes certain waste, but also affects the soil environment. The soil nutrient rapid detection device is used for detecting soil components, not only can detect the real-time state of the soil in real time, but also can adopt different fertilization schemes according to different crops, thereby achieving the purpose of higher crop yield. The device makes the health condition that detects crops informationized more, intelligent, succinct and high-efficient. The device is widely applied to various industries such as farms, water orchards, vegetable industries, crop bases and the like.
In recent years, digital microfluidics has been applied in many fields such as: detection fields such as accounting detection, protein detection, amino acid detection and the like. The system is intended to integrate laboratory-implemented functions onto a coin-like size chip, which highly integrated and miniaturized chip may be referred to as a "lab-on-a-chip". The digital microfluidic platform can realize micro-operation on liquid drops, and the operated liquid drops can even reach microlitres. The digital microfluidic platform can change the surface tension of the liquid drop by changing the electric field so as to change the hydrophilicity of the liquid drop to a certain degree. When the electrode is electrified, the liquid drop on the hydrophobic layer generates a surface tension gradient towards the electrode side, the generated force is larger than the force generated by contact angle hysteresis, and the liquid drop moves towards the electrode side.
Disclosure of Invention
The automatic detection device for the soil nutrients based on the digital microfluidics can at least solve one of the technical problems, can realize more efficient and rapid detection of the soil nutrients, and reduces unnecessary waste in the fertilization process.
In order to achieve the above purpose, the present invention adopts the following technical scheme:
the automatic soil nutrient detection device based on digital microfluidic comprises a capillary electrophoresis analyzer and a digital microfluidic platform, and is characterized by further comprising a microfluidic pump, a matrix electrode array and a matrix electrode control module;
firstly, carrying out pretreatment on soil sample liquid through filter paper, then separating impurities again through a solid-liquid extractor, and then controlling liquid drops to enter a digital microfluidic platform through a microfluidic pump;
the matrix electrode control module controls the flow of liquid drops by controlling the matrix electrode array, the capillary electrophoresis analyzer detects the liquid drops reaching the designated position, and the detection result is displayed by a computer.
Furthermore, the device comprises 4 sample inlets which are respectively used for adding the liquid to be detected and the buffer solution, and the sample inlets can also be used for measuring the volume of the solution;
the first sample inlet for adding the soil solution to be detected is provided with an additional solid-liquid separator for solid-liquid separation of the soil solution, and other buffer solution sample inlets are not provided;
the four sample inlets are provided with a microfluidic pump for controlling the speed and the size of the liquid drops entering the digital microfluidic platform.
Furthermore, the four sample inlets are all provided with a glass container which is fixed with the plastic groove;
the first sample inlet is connected with the solid-liquid separator through a rubber pipeline for further separating soil solution, and other sample inlets are directly connected with the micro-flow pump.
Further, the lower part of the mouth of the micro-flow pump is fixed by being embedded into the plastic groove, the liquid inflow end of the micro-flow pump is connected with the solid-liquid separator at the first sample inlet, the micro-flow pumps of other sample inlets are directly connected with the corresponding sample inlets, and the liquid outlet of the micro-flow pump is horizontally embedded into the digital micro-flow platform through a pipe.
Further, the digital microfluidic platform consists of a plastic base and 12×8 pieces of 1.5×1.5mm 2 The electrode array, the dielectric layer and the hydrophobic layer jointly form the front surface of the PCB;
the back of the PCB is a crystal array connected with the positive plate, and the lead-out wire is connected with a relay so as to control the conduction of the digital microfluidic electrode, and the power supply is 300V when the electrode is conducted and the normal state is grounded; the matrix electrode control module controls the electrode array through a control relay.
Further, the matrix electrode control module comprises an STM32 singlechip, 20 relays, 96 transistors and 2 power supplies;
the STM32 singlechip sends control signals to the 12 row relays and the 8 column relays, so that the effect that the row line or the column line where the relays are is connected with a power supply 300V is controlled; the relay is grounded when not receiving the instruction; the grid electrode of each row is led out to be connected with the relay, and the source electrode of each column is led out to be connected with the other group of relays; the conduction of the digital microfluidic electrode plate is controlled by the row relay and the column relay together, so that the effect of controlling liquid drops is achieved.
Furthermore, the dielectric layer adopts a magnetron sputtering method SiO 2 And depositing a dielectric layer, wherein the thickness of the dielectric layer is larger than 200nm.
Furthermore, the hydrophobic layer adopts a Teflon solution as a chip, and the Teflon solution is coated on the SiO-passing chip 2 And spin-coating the electrode plate deposited with the dielectric layer to obtain the nanoscale hydrophobic layer.
Further, the device also comprises a detection module, wherein the syringe needle is fixed at a designated position, the capacitive coupling non-contact conductivity detector plays a role in detection, separation is needed to be provided for a detection system, and a detection result is displayed on a computer end.
Further, the device also comprises an upper computer display control module, and a computer end is specifically adopted, so that the monitored concentration is displayed by the computer end, and the control of the liquid drops of the digital microfluidic platform is realized, and the computer end is connected with the capillary electrophoresis analyzer and the matrix electrode control module.
According to the technical scheme, the automatic soil nutrient detection device based on digital micro-flow control comprises a capillary electrophoresis apparatus, digital micro-flow control, a computer, a solid-liquid extractor, a micro-pump and the like. The specific operation steps can be realized by the following steps: firstly, fully mixing soil with water, filtering the soil in the liquid to be detected by using a funnel and filter paper, then pouring the liquid to be detected into a sample inlet, and separating the solid from the liquid in a further step after passing through a solid-liquid extractor. And then the liquid to be detected can be conveyed to a digital micro-fluidic platform through a micro-pump, and then the liquid drops are mixed, separated and the like. And finally, measuring the required concentration of the liquid drops by a CE analyzer. The device can be used for detecting soil nutrients, such as nutrient elements including nitrogen, phosphorus, potassium and the like.
The automatic soil nutrient detection device based on liquid drop microfluidics, namely capillary electrophoresis analysis (CE analysis), can rapidly detect nutrient elements such as nitrogen, phosphorus, potassium and the like in soil through an electrophoresis chart. CE analysis already has a certain market share in the modern agricultural inspection market. The soil detection method has the advantages of less sampling, high detection efficiency, higher detection sensitivity and the like.
Specifically, the invention has simple structure and small volume of the required liquid to be measured. The digital microfluidic platform can separate liquid drops and mix different operations. The liquid drop can accurately control the size of the liquid drop through the micropump. The invention can store the monitored data through the computer. The invention can realize the driving of different paths of liquid drops through computer software.
Drawings
FIG. 1 is a schematic diagram of the overall digital microfluidic architecture of the present invention;
fig. 2 is a schematic top view of the digital microfluidic platform of the present invention;
FIG. 3 is a schematic view of a cut-plane structure of the digital microfluidic system according to the present invention;
FIG. 4 is a matrix electrode module of the present invention;
FIG. 5 is a schematic diagram of a soil testing process according to the present invention;
fig. 6 is a block diagram of the overall structure of digital microfluidic according to the present invention;
fig. 7 is a schematic diagram of a digital microfluidic drive.
1, a computer; 2, a capacitively coupled non-contact conductivity detector; 3, a glass container; 4, separating voltage is-14 kv;5, a micropump; 6, a solid-liquid separator; 7, a sample inlet; 8, injecting needle tube of CE analyzer; 9, grounding; 10, a digital microfluidic platform; 11, a digital microfluidic sample inlet; 12, an STM32 singlechip; 13, a hydrophobic layer; 14, a dielectric layer; 15, electrodes; 16, a plastic base; 17 denotes a transistor;
wherein 5 is a micro-flow pump, which is used for controlling the volume of liquid drops and the generation speed of the liquid drops; 10 represents the whole microfluidic platform, 11 is a sample inlet of the digital microfluidic platform, and 8 is the concentration of the liquid drops for analysis by a CE analyzer;
wherein 14 denotes a dielectric layer, 15 denotes an electrode, and 17 denotes a transistor; the same structure is used elsewhere to form 96 electrodes, 96 transistors and 20 inputs.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention.
As shown in fig. 1 to 7, the automatic soil nutrient detecting device based on digital microfluidic according to the present embodiment is a system composed of a micropump 5, a capillary electrophoresis analyzer, and a digital microfluidic platform 10.
First, the invention has 4 sample inlets, a first sample inlet, a second sample inlet, a third sample inlet and a fourth sample inlet 7. The sample injection port can be used for adding the liquid to be detected and the buffer solution, and the sample injection port can also be used for measuring the volume of the solution. The first sample inlet for the soil solution to be tested is provided with an additional solid-liquid separator 6 for solid-liquid separation of the soil solution, and the other buffer sample inlets are not provided.
Each of the four sample inlets has a microfluidic pump 5 for controlling the speed and size of the droplets as they enter the digital microfluidic platform. This is followed by a digital microfluidic platform 10 whose base is fabricated by 3D printing technology, with 8 x 12 1.5 x 1.5mm2 electrodes designed by way of a printed circuit board, as shown in fig. 2. The digital microfluidic platform adopts a structure of a single polar plate, and the module is composed of a plastic bottom plate 15, an electrode layer 16 composed of chromium metal, a dielectric layer 14 and a hydrophobic layer 13 composed of Teflon. The capillary electrophoresis apparatus comprises a detection system consisting of a capacitive coupling non-contact conductivity detector 2, a CE analyzer injection needle tube 8, a computer terminal 1, a glass container 3, a separation voltage of 4-14kv, a ground 9 and the glass container 3.
The sample injection module adopts a first sample injection port, a second sample injection port, a third sample injection port and a fourth sample injection port 7. The four sample inlets are all provided with a glass container and a plastic groove for fixing, and the structure can realize better replacement and cleaning of the sample inlets. Wherein the first sample inlet is connected with the solid-liquid separator 6 through a rubber pipeline for further separating soil solution, and the other sample inlets are directly connected with the micro-flow pump 5.
The microfluidic pump module 5 is a module which is fixed below the inlet through being embedded into a plastic groove, the liquid inflow end of the microfluidic pump is connected with the solid-liquid separator 6 at the first sample inlet, and the microfluidic pumps of other sample inlets are directly connected with the sample inlet 11. The liquid outlet of the microfluidic pump is horizontally embedded into the digital microfluidic platform through a pipe.
The digital microfluidic platform consists of a plastic base, 12×8 pieces of 1.5×1.5mm 2 The electrode array (as shown in fig. 2), the dielectric layer 14, and the hydrophobic layer 13 together form the front surface of the PCB board. The back of the PCB board is mainly a crystal array connected with the positive plate, and the lead-out wires are connected with the relay. And further control the conduction of the digital microfluidic electrode, wherein the power supply is 300V when the electrode is conducted, and the normal state is the grounding. The plastic base can be manufactured by a 3d printer. The hydrophobic layer is made of Teflon material. The singlechip controls the electrode array through the control relay.
The design adopts a 12×8 (96) electrode array, and the traditional digital micro-flow control needs to introduce M×N input ends to M×N electrodes. But if active matrix driving is chosen, only M + N inputs are required. The method can greatly reduce the number of buses required for inputting control signals.
The matrix electrode control module adopted by the design comprises an STM32 singlechip 12, 20 relays, 96 transistors (CS 2N60 load 2A, 200V) and 2 power supplies. The STM32 singlechip (model STM32f103C8T 6) sends control signals to the 12 row relays and the 8 column relays (model CDZ9-52PAC 220V), so that the effect that the row line or the column line where the relays are located is connected with the power supply 300V is controlled. The relay is grounded when it does not receive an instruction. The grid electrode of each row is led out to be connected with the relay, and the source electrode of each column is led out to be connected with the other group of relays. The conduction of the digital microfluidic electrode plates is controlled by the row relay and the column relay together (as shown in fig. 4). Thereby achieving the effect of controlling the liquid drop.
To facilitate understanding of the driving process of the droplet, 2 rows and 2 columns are selected from the electrode array for explanation, and are simply represented as shown in fig. 7. R1 and R2 are respectively connected with the gates of all transistors in the first row and the gates of all transistors in the second row. C1 C2 represents the connections to the gates of all transistors of the first column and to the sources of all transistors of the second column, respectively. R1C1, R1C2, R2C1 and R2C1 represent a first row and a first column, a first row and a second column, a second row and a first column, and a second row and a second column, respectively. In the stage of R1C1, only R1 rows and C1 columns are at high level, the electrode plate is connected with 300V (the connection voltage is opened only when R1 and C1 are at high level at the same time), so that the liquid drops have a tendency to move to R1C1 due to the effect of dielectric wetting; in the stage of R1C2, only the R1C2 electrode plate is conducted (R1 and C2 are simultaneously high-level, namely an on electrode exists), so that the liquid drops have a tendency to move to R1C2 due to the effect of dielectric wetting; in the stage of R2C2, only the electrode plate of R2C2 is conducted (R2 and C2 are at high level at the same time, and the electrode is conducted for 300V), so that the liquid drops tend to move towards R2C2 due to the effect of dielectric wetting. The resulting trend of droplet movement is shown in the upper right hand corner of the figure, with the droplet moving from the first row first column to the first row second column and then to the second row second column (as shown in fig. 4).
The design adopts a magnetron sputtering method SiO 2 And depositing a dielectric layer, wherein the thickness of the dielectric layer is larger than 200nm. Here, a Teflon solution is selected as the hydrophobic layer 13 of the chip, and is coated on the SiO-passing layer 2 And spin-coating the electrode plate deposited with the dielectric layer to obtain the nanoscale hydrophobic layer.
The detection module. With the syringe needle 8 fixed in a specific position, the capacitively coupled non-contact conductivity detector serves as a detector, wherein a separate supply is required for the detection system. And displaying the detection result to a computer end.
And the upper computer displays the control module. The computer end 1 can display the monitored concentration and can also realize the control of the liquid drops of the digital microfluidic platform. The computer is connected with the CE analyzer 8 and the STM32 singlechip 12.
The STM32 singlechip 12 is connected with the computer 1 and the electrode array, and can realize communication with the computer and control of the electrode array.
After mixing the soil to be tested with water, the solution to be tested is filtered by a funnel and a beaker, and then the sample solution of the soil is poured into a sample inlet and then passes through a solid-liquid extractor 6. By this means, further solids can be separated from the liquid and the droplets separated by the solid extractor 6 can then be transported by the micropump 5 to the digital micro-fluidic platform. At this time, the control of the microfluidic pump can be realized by controlling the computer end, so that liquid drops orderly enter the digital microfluidic platform. In order to realize the control of the electrodes, the computer end needs to control the electrode array so as to realize the operations of liquid drop movement and the like. The droplets are then transported by a computer controlled digital microfluidic platform to CE capillary inlet 8 for detection by a non-contact conductivity detector. Finally, checking the detected concentration through a computer terminal.
Fig. 5 shows a structural diagram of the entire operation process. The soil sample liquid is pretreated by filter paper, then impurities are separated again by a solid-liquid extractor, and then a microfluidic pump controls liquid drops to enter a digital microfluidic platform. The STM32 singlechip controls the flow of liquid drops through the control electrode array, the CE analyzer detects the liquid drops reaching the designated positions, and the detection result is displayed through a computer.
Fig. 6 shows a flow chart of the entire system. The STM32 singlechip can realize the control of the micro-flow pump and the matrix electrode, thereby achieving the effect of integrally controlling the digital micro-flow control platform. CE analyzer detection may be performed when a droplet is moved to a specified detection position. Finally, the control of the singlechip and the display of the detection result are realized through the upper computer.
In summary, the automatic soil nutrient detection device based on digital microfluidic provided by the invention comprises computer software, an STM32 singlechip, a CE analyzer, a digital microfluidic platform, a microfluidic pump, a solid-liquid separator and the like.
After mixing the soil to be tested with water, the solution to be tested is filtered by a funnel and a beaker, and then the sample solution of the soil is poured into a sample inlet and then passes through a solid-liquid extractor 6. By this means, the solids and liquids can be separated again, and the output of the sample to be tested is then connected to a micropump 5, which delivers the droplets separated by the solid extractor to a digital microfluidic platform (as shown in fig. 2). The sample droplets are transported by the digital microfluidic platform to the CE capillary inlet 8 for detection by a non-contact conductivity detector. The working buffer solution and other solvents required by the experiment can also be controlled by a digital microfluidic platform to carry out operations such as moving and mixing, and finally transported to a CE capillary inlet for detection.
The substrate of the digital micro-fluidic platform adopts an epoxy resin single-sided copper-clad laminate, the base of the whole device is manufactured by a 3D printing technology, and 8 multiplied by 12 is 1.5 multiplied by 1.5mm by design by a printed circuit board 2 An electrode.
The digital microfluidic platform adopts a structure of a single polar plate, the polar plate is made of glass material, and the upper side of the polar plate is a hydrophobic layer (shown in figure 3) consisting of a chromium metal electrode, a dielectric layer and Teflon.
The capillary for CE analysis was located perpendicular to the center of the electrode array (height 2 mm above the array).
The micro-pump can be operated by a computer, and the liquid drops of the micro-fluidic platform are controlled and CE (CE) analysis of the liquid drops is realized.
The system of the embodiment of the invention combines the solid-liquid separation, the microfluidic pump, the digital microfluidic platform and the CE analyzer (shown in figure 1). Control of droplet size, control of droplet flow, and detection of concentration can be achieved. Wherein simultaneous manipulation of a plurality of droplets can be achieved, the efficiency of droplet manipulation. The CE analyzer can record the concentration of the droplets at different moments during the reaction of the droplets at different sample inlets, and even can perform the configuration and other operations on the trace solution.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. The automatic soil nutrient detection device based on digital microfluidic comprises a capillary electrophoresis analyzer and a digital microfluidic platform, and is characterized by further comprising a microfluidic pump, a matrix electrode array and a matrix electrode control module;
firstly, carrying out pretreatment on soil sample liquid through filter paper, then separating impurities again through a solid-liquid extractor, and then controlling liquid drops to enter a digital microfluidic platform through a microfluidic pump;
the matrix electrode control module controls the flow of liquid drops by controlling the matrix electrode array, the capillary electrophoresis analyzer detects the liquid drops reaching the designated position, and the detection result is displayed by a computer.
2. The digital microfluidic based automatic detection device for soil nutrients according to claim 1, wherein: the device comprises 4 sample inlets which are respectively used for adding the liquid to be detected and the buffer solution, and the sample inlets can also be used for measuring the volume of the solution;
the first sample inlet for adding the soil solution to be detected is provided with an additional solid-liquid separator for solid-liquid separation of the soil solution, and other buffer solution sample inlets are not provided;
the four sample inlets are provided with a microfluidic pump for controlling the speed and the size of the liquid drops entering the digital microfluidic platform.
3. The digital microfluidic based automatic detection device for soil nutrients according to claim 2, wherein:
the four sample inlets are all provided with a glass container and a plastic groove for fixing;
the first sample inlet is connected with the solid-liquid separator through a rubber pipeline for further separating soil solution, and other sample inlets are directly connected with the micro-flow pump.
4. The digital microfluidic based automatic detection device for soil nutrients according to claim 3, wherein:
the lower part of the mouth of the micro-flow pump is fixed by being embedded into the plastic groove, the liquid inflow end of the micro-flow pump is connected with the solid-liquid separator at the first sample inlet, the micro-flow pumps of other sample inlets are directly connected with the corresponding sample inlets, and the liquid outlet of the micro-flow pump is horizontally embedded into the digital micro-flow control platform through a pipe.
5. The digital microfluidic based automatic detection device for soil nutrients according to claim 1, wherein:
the digital microfluidic platform consists of a plastic base and 12 multiplied by 8 pieces of 1.5 multiplied by 1.5mm 2 The electrode array, the dielectric layer and the hydrophobic layer jointly form the front surface of the PCB;
the back of the PCB is a crystal array connected with the positive plate, and the lead-out wire is connected with a relay so as to control the conduction of the digital microfluidic electrode, and the power supply is 300V when the electrode is conducted and the normal state is grounded; the matrix electrode control module controls the electrode array through a control relay.
6. The digital microfluidic based automatic detection device for soil nutrients according to claim 1, wherein: the matrix electrode control module comprises an STM32 singlechip, 20 relays, 96 transistors and 2 power supplies;
the STM32 singlechip sends control signals to the 12 row relays and the 8 column relays, so that the effect that the row line or the column line where the relays are is connected with a power supply 300V is controlled; the relay is grounded when not receiving the instruction; the grid electrode of each row is led out to be connected with the relay, and the source electrode of each column is led out to be connected with the other group of relays; the conduction of the digital microfluidic electrode plate is controlled by the row relay and the column relay together, so that the effect of controlling liquid drops is achieved.
7. The automatic detection device for soil nutrients based on digital microfluidics according to claim 5, wherein: the dielectric layer adopts a magnetron sputtering method SiO 2 And depositing a dielectric layer, wherein the thickness of the dielectric layer is larger than 200nm.
8. The digital microfluidic based automatic detection device for soil nutrients according to claim 7, wherein: the hydrophobic layer adopts a Teflon solution as a chip, and the Teflon solution is coated on the SiO-passing chip 2 And spin-coating the electrode plate deposited with the dielectric layer to obtain the nanoscale hydrophobic layer.
9. The digital microfluidic based automatic detection device for soil nutrients according to claim 1, wherein: the detection module is fixed at a designated position by adopting a syringe needle, and the capacitive coupling non-contact conductivity detector plays a role in detection, wherein separation is needed to be provided for a detection system, and a detection result is displayed on a computer end.
10. The digital microfluidic based automatic detection device for soil nutrients according to claim 1, wherein: the system also comprises an upper computer display control module, and a computer end is specifically adopted, the computer end is used for displaying the monitored concentration and controlling the liquid drops of the digital microfluidic platform, and the computer end is connected with the capillary electrophoresis analyzer and the matrix electrode control module.
CN202211668141.1A 2022-12-23 2022-12-23 Automatic soil nutrient detection device based on digital microfluidic control Pending CN116223596A (en)

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