Sewage heavy metal ion detection device

Abstract

The invention discloses a sewage heavy metal ion detection device, which belongs to the technical field of sewage detection, and comprises a sensor module and a microfluidic module, the sensor module comprises a Loff wave surface acoustic wave device, the Loff wave surface acoustic wave device comprises a resonance area and two Loff wave interdigital transducers, the resonance area is located between the two Loff wave interdigital transducers, and the resonance area is covered with a heavy metal ion adsorption film; the micro-fluidic module comprises a micro-channel system and a Rayleigh wave surface acoustic wave device, the micro-channel system comprises a dropwise adding tank, a micro-channel and a waste liquid tank which are communicated in sequence, the micro-channel is provided with an experimental area overlapped with the resonance area, and the Rayleigh wave surface acoustic wave device is used for driving sewage to move from the dropwise adding tank to the waste liquid tank. By combining a microfluidic technology and a surface acoustic wave technology, heavy metal ions, especially lead ions, in sewage can be rapidly, accurately and conveniently monitored.

Description

Technical Field

[0001] The invention relates to the technical field of sewage detection, and in particular to a sewage heavy metal ion detection device. Background Art

[0002] Heavy metal ion pollution in the water environment refers to the pollution of water bodies caused by heavy metal ions contained in pollutants entering the water environment. Heavy metal ions are widely distributed in lakes, mud, soil and other environments, mainly from natural and human factors, such as industrial processes such as mining, machinery manufacturing, chemical industry, electronics, instrumentation and automobile exhaust. Even if the concentration of heavy metal ions in the natural environment is at a trace level, it can often accumulate to high concentrations in the human body through bioaccumulation. If it exceeds the threshold, it will cause serious health disorders and cause diseases. Therefore, in the field of heavy metal detection, how to quickly, accurately and conveniently detect methods has always been the goal pursued by researchers. Summary of the invention

[0003] The purpose of the present invention is to solve the above technical problems and provide a sewage heavy metal ion detection device, which utilizes a combination of microfluidics technology and surface acoustic wave technology to quickly, accurately and conveniently monitor heavy metal ions, especially lead ions, in sewage.

[0004] To achieve the above-mentioned object, the present invention provides the following solutions: The present invention discloses a sewage heavy metal ion detection device, comprising a sensor module and a microfluidic module;

[0005] The sensor module comprises a Love wave surface acoustic wave device, the Love wave surface acoustic wave device comprises a resonance region and two Love wave interdigital transducers, the resonance region is located between the two Love wave interdigital transducers, and the resonance region is covered with a heavy metal ion adsorption film;

[0006] The microfluidic module includes a microfluidic system and a Rayleigh wave surface acoustic wave device. The microfluidic system includes a dripping tank, a microfluidic channel and a waste liquid tank connected in sequence. The microfluidic channel has an experimental area overlapping with the resonance area. The Rayleigh wave surface acoustic wave device is used to drive the sewage to move from the dripping tank to the waste liquid tank.

[0007] Preferably, valves are provided at the connection points between the microchannel and the dripping tank and the waste liquid tank.

[0008] Preferably, the microchannel is a rectangular channel with a length of 3000 μm, a width of 1000 μm and a depth of 1000 μm, and the drip trough and the waste liquid trough are circular with a radius of 1785 μm and a depth of 1000 μm.

[0009] Preferably, the Rayleigh wave surface acoustic wave device comprises a mounting plate and a Rayleigh wave interdigital transducer, and the Rayleigh wave interdigital transducer and the drip tank are mounted on the mounting plate.

[0010] Preferably, the heavy metal ion adsorption membrane is made of cross-linked polyethylene imine dithiocarbamate polymer heavy metal ion adsorption material.

[0011] Preferably, the drip tank, the microchannel and the waste liquid tank are integrally made of polydimethylsiloxane material.

[0012] Preferably, the Love wave IDT is a delay line IDT.

[0013] Preferably, the delay line type IDT is made of metal aluminum, has a thickness of 0.8 μm, a wavelength of 20 μm, an aperture of 1500 μm, 10 to 20 pairs of fingers, a finger width and spacing of 5 μm, and a delay distance of 2000 μm.

[0014] Preferably, the Love wave surface acoustic wave device further comprises a quartz substrate and two sound absorbers, a silicon dioxide waveguide layer is provided on the quartz substrate, the Love wave interdigital transducers and the sound absorbers are mounted on the silicon dioxide waveguide layer, and the two Love wave interdigital transducers are located between the two sound absorbers.

[0015] Preferably, the quartz substrate is made of ST-cut quartz, the cutting angle is 90 degrees, and the thickness of the quartz substrate is 100 μm.

[0016] Compared with the prior art, the present invention has achieved the following technical effects:

[0017] The sewage heavy metal ion detection device in the present invention is a detection device that combines microfluidics and surface acoustic wave technology. Microfluidics is a technology that manipulates liquids through microchannels, which can concentrate multiple operation steps on a micron scale, thereby simplifying the operation steps, shortening the detection time, and reducing reagent consumption, thereby achieving rapid and high-throughput detection. The surface acoustic wave technology uses the heavy metal ion adsorption membrane to adsorb heavy metal ions, and the heavy metal ions are combined with specific ligands to form a complex, which will affect the propagation speed and impedance of the surface acoustic wave, thereby generating a specific electrical signal change. By measuring this signal change, the existence and concentration of heavy metal ions can be accurately detected, thereby realizing heavy metal detection of the sewage to be tested in the microchannel, especially lead ions, and has good anti-interference ability and reproducibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is the sewage heavy metal ion detection device in the embodiment;

[0020] Figure 2 is a Love wave surface acoustic wave device in an embodiment;

[0021] Figure 3 is a schematic diagram of design parameters of a Love wave interdigital transducer in an embodiment;

[0022] Figure 4 is a schematic diagram of design parameters of a Love wave surface acoustic wave device in an embodiment;

[0023] Figure 5 Schematic diagram of design parameters of the microfluidic system in the embodiment.

[0024] Explanation of the reference numerals: 1. quartz substrate; 2. Love wave interdigital transducer; 3. resonance zone; 4. sound absorber; 5. dripping tank; 6. microfluidic channel; 7. waste liquid tank; 8. valve mounting slot; 9. mounting plate; 10. Rayleigh wave interdigital transducer. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] This embodiment provides a sewage heavy metal ion detection device, such as Figures 1 to 5As shown, it includes a sensor module and a microfluidic module; the sensor module includes a Love wave surface acoustic wave device, and the Love wave surface acoustic wave device includes a Love wave interdigital transducer 2 and a resonance zone 3. There are two Love wave interdigital transducers 2, and the resonance zone 3 is located between the two Love wave interdigital transducers 2. The resonance zone 3 is covered with a heavy metal ion adsorption film for capturing heavy metal ions. The microfluidic module includes a microfluidic system and a Rayleigh wave surface acoustic wave device 10. The microfluidic system includes a drip tank 5, a microfluidic channel 6 and a waste liquid tank 7 connected in sequence. The microfluidic channel 6 has an experimental area that overlaps with the resonance zone 3. The Rayleigh wave surface acoustic wave device 10 is used to drive the sewage from the drip tank 5 to the waste liquid tank 7. Compared with Rayleigh waves, Lamb waves and SH waves, Love waves are more suitable for dealing with liquids to be tested with lower heavy metal ion concentrations, so Love wave surface acoustic wave devices are used. In microfluidics, SH waves and love waves are horizontal propagation modes, which leads to weak coupling with liquids and is not conducive to driving liquids. Therefore, Rayleigh waves are used to drive liquids.

[0027] Working process:

[0028] First, one Love wave interdigital transducer 2 in the Love wave surface acoustic wave device is connected to the excitation signal and the other Love wave interdigital transducer 2 is connected to the spectrum analyzer, the initial state resonant frequency is measured, and then the excitation signal and the spectrum analyzer are turned off; then, the liquid to be tested is dripped into the dripping tank 5, and the Rayleigh wave surface acoustic wave device 10 is turned on to drive the droplets in the dripping tank 5 to flow into the microchannel 6, and after passing through the experimental area, flow into the waste liquid tank 7; then, after the liquid completely flows into the waste liquid tank 7, the Rayleigh wave surface acoustic wave device 10 is turned off, and after the residual water in the experimental area is completely evaporated, the excitation signal and the spectrum analyzer are connected again to measure the change in the resonant frequency, and the change is the heavy metal ion content in the droplet. The method of separately performing the Rayleigh wave surface acoustic wave device 10 and the Love wave surface acoustic wave device in the driving and detection process can avoid mutual interference between the two, and is more conducive to ensuring the accuracy of the detection.

[0029] Working principle:

[0030] The microfluidic module uses microfluidic technology, which is a technology that manipulates liquids through microchannels. It can concentrate multiple operation steps such as sample pretreatment, concentration, reaction, separation and detection on a micrometer scale. It has the advantages of simple operation, short detection time, low reagent consumption, good portability and high-throughput detection. The sensor module uses surface acoustic wave technology. Surface acoustic wave is an elastic wave whose vibration direction is perpendicular to the medium and propagates along the surface of the medium. Unlike other sound waves, surface acoustic wave does not pass through the surface of the medium, but propagates on the surface. Specifically, after the heavy metal ion adsorption membrane adsorbs heavy metal ions, the heavy metal ions combine with specific ligands, and the complex formed will affect the propagation speed and impedance of the surface acoustic wave, thereby generating specific electrical signal changes. By measuring this signal change, the presence and concentration of heavy metal ions can be accurately detected, and trace heavy metal ions can be detected, and it has good anti-interference ability and reproducibility.

[0031] In one embodiment, if Figures 1 to 5 As shown, valves are provided at the connection between the microchannel 6 and the drip tank 5, and at the connection between the microchannel 6 and the waste liquid tank 7. Figure 1 As shown, the valve installation groove 8 on the side wall of the microchannel 6 is used to install the valve. After the liquid to be tested is dripped into the dripping tank 5, the valve needs to be closed. After the initial state resonant frequency is measured, the valve is opened again to turn on the Rayleigh wave surface acoustic wave device 10, drive the droplet to flow through the experimental area, and then flow into the waste liquid tank 7.

[0032] In one embodiment, if Figures 1 to 5 As shown, the microchannel in this design only serves as a control tool for reaction conditions, so a rectangular channel is used. The length of the rectangular channel is 3000μm, the width is 1000μm, and the depth is 1000μm. It can be calculated that the total volume of the microchannel 6 is 3μL. The drip trough 5 and the waste liquid trough 7 are circular, and the radius of the drip trough 5 and the waste liquid trough 7 is 1785μm and the depth is 1000μm. Since the minimum capacity of a common pipette is generally 10μL, the volume of the liquid to be tested added each time is basically 10μL. In order to reduce the head loss, the drip trough 5 needs to be able to accommodate the volume of the liquid added, and its radius is at least 1784.5μm. To ensure that there is no overflow, the radius is selected to be 1785μm. Of course, the above parameters can be adjusted according to actual needs.

[0033] In one embodiment, if Figures 1 to 5As shown, the Rayleigh wave surface acoustic wave device includes a mounting plate 9 and a Rayleigh wave interdigital transducer 10. The Rayleigh wave interdigital transducer 10 and the drip tank 5 are mounted on the mounting plate 9. The Rayleigh wave interdigital transducer 10 is located beside the drip tank 5 and in the length direction of the microchannel 6. The Rayleigh wave interdigital transducer 10 is arranged on one side, which is more conducive to the droplets in the experimental area moving from the drip tank 5 to the waste liquid tank 7. The number of interdigital pairs of the Rayleigh wave interdigital transducer 10 can be 20 pairs.

[0034] In one embodiment, if Figures 1 to 5 As shown, the heavy metal ion adsorption membrane is made of cross-linked polyethylene imine dithiocarbamate polymer heavy metal ion adsorption material. The heavy metal ion adsorption membrane is the core part of the sewage heavy metal ion detection device. The heavy metal ion adsorption membrane is placed in the resonance zone 3. When the mass of the heavy metal ion adsorption membrane changes, the propagation of the sound wave in the resonance zone 3 is affected, resulting in a change in the resonance frequency of the resonance zone 3. By observing the relationship between the change in the resonance frequency and the mass load, the amount of the target substance collected by the sensitive membrane can be determined.

[0035] The cross-linking of polyethyleneimine (PEI) and glutaraldehyde is carried out to form carbon-nitrogen double bonds, and then these bonds are reduced with sodium borohydride, and finally the cross-linked polymer heavy metal ion adsorption material of PEI grafted dithiocarbamate is prepared by reaction with carbon disulfide to obtain the cross-linked polyethyleneimine dithiocarbamate polymer heavy metal ion adsorption material. The material is simple to prepare, has high adsorption capacity, is insoluble in water, has low production cost, has high stability and adsorption capacity for various heavy metal ions (especially lead ions), and is also light in weight.

[0036] In one embodiment, if Figures 1 to 5 As shown, the dripping tank 5, the microchannel 6 and the waste liquid tank 7 are made of polydimethylsiloxane material in one piece.

[0037] In one embodiment, if Figures 1 to 5 As shown, the Love wave IDT 2 adopts a delay line IDT.

[0038] In one embodiment, if Figures 1 to 5 As shown, the delay line type interdigital transducer is made of metal aluminum. Common materials for interdigital transducers are Al, Ag and Au. Due to economic factors, Al is used as the material of the interdigital transducer. The thickness of the delay line type interdigital transducer is 0.8μm, the wavelength is 20μm, the aperture is 1500μm, the number of finger pairs is 10 to 20 pairs, the number of interdigital pairs is 75 pairs, the width and spacing of the fingers are both 5μm, and the delay distance is 2000μm, to ensure that the resonance area 3 is large enough to accommodate the heavy metal ion adsorption film. Of course, the above parameters can be adjusted according to actual needs.

[0039] In one embodiment, if Figures 1 to 5 As shown, the Love wave surface acoustic wave device also includes a quartz substrate 1 and two sound absorbers 4. A silicon dioxide waveguide layer is provided on the quartz substrate 1. The Love wave interdigital transducers 2 and the sound absorbers 4 are installed on the silicon dioxide waveguide layer. The two Love wave interdigital transducers 2 are located between the two sound absorbers 4. The sound absorbers 4 are made of sound-absorbing glue.

[0040] In one embodiment, if Figures 1 to 5 As shown, the quartz substrate 1 adopts ST-cut quartz with a cutting angle of 90 degrees. This cutting method allows the surface of the crystal to support lateral surface acoustic wave propagation while avoiding the generation of longitudinal acoustic waves. The thickness of the quartz substrate 1 is 100 μm, which is the minimum substrate thickness while meeting the design requirements and mechanical strength, and can save materials. Of course, if the thickness of the quartz substrate 1 is above 100 μm, it is also acceptable. The thickness of the silicon dioxide waveguide layer should not be too thick, and should be much smaller than the thickness of the quartz substrate 1. At the same time, in order to save materials, it is more appropriate to select the thickness of the silicon dioxide waveguide layer to be 1 μm. Of course, the thickness of the silicon dioxide waveguide layer can be adjusted according to actual conditions.

[0041] In one embodiment, if Figures 1 to 5 As shown, the quartz substrate 1 and the resonance region 3 are rectangular regions, the length of the quartz substrate 1 is 5650um, and the width is 1910um. The length of the resonance region 3 is 1910μm, and the width is 1000um. The length direction of the resonance region 3 is perpendicular to the length direction of the quartz substrate 1. The rectangular flow channel coincides with the center of the resonance region 3, and the length direction of the rectangular flow channel is perpendicular to the length direction of the quartz substrate 1. Of course, the above values ​​can be adjusted according to actual conditions.

[0042] In one embodiment, if Figures 1 to 5 As shown:

[0043] Method for manufacturing Love wave interdigital transducer:

[0044] (1) Wash the culture dish with deionized water, blow it off with nitrogen and then wash it again;

[0045] (2) Put the developer into a dish, wet the non-woven cloth and wipe the wafer, then blow nitrogen off the wafer surface, and then wipe the wafer with anhydrous ethanol and acetone;

[0046] (3) Place the wafer on a photoresist machine, add photoresist, close the lid, and rotate it in the machine;

[0047] (4) Carefully peel off the wafer and place it on a heating table. After heating, remove the wafer and place it on a heat-resistant material;

[0048] (5) Adjust the photolithography machine table, turn on the air pump, insert the mask, and place the wafer under the mask;

[0049] (6) Align the light and start photolithography (exposure mode). After completion, remove the wafer and put it back into the heating table. After heating, remove the wafer and let it stand.

[0050] (7) Put the developer in a dish, soak the wafer in the developer, then rinse with deionized water, and put it into the coating machine again;

[0051] (8) Remove the wafer and wipe it;

[0052] (9) After completion, place the product under a microscope to observe the effect.

[0053] Method for manufacturing silicon dioxide waveguide layer:

[0054] (1) Cleaning: First, use acetone, anhydrous ethanol and ultrapure water to clean the quartz substrate in sequence, and then blow dry with nitrogen for later use;

[0055] (2) Vacuuming: The quartz substrate is placed on the stage of the magnetron sputtering coating chamber and fixed, and a mechanical pump is used to perform rough vacuuming. After a certain vacuum value is reached, a molecular pump is used to evacuate the entire vacuum chamber;

[0056] (3) Adjusting the argon gas: After the vacuum degree is stable, introduce argon gas into the vacuum chamber, set the argon flow rate and adjust the air pressure in the vacuum chamber;

[0057] (4) Pre-sputtering oxygen: Turn on the RF power supply to generate glow, stabilize the air pressure in the vacuum chamber, and then introduce an equal flow of oxygen for pre-sputtering to remove dirt on the target surface;

[0058] (5) Sputtering of silicon dioxide film: After pre-sputtering, the RF power is increased, the cover plate shielding the substrate is rotated open, magnetron sputtering is started, and a silicon dioxide waveguide layer is grown on the quartz substrate.

[0059] Microfluidic channel preparation by photocuring printing:

[0060] (1) Import the completed microfluidic model file (.stl) into the slicing software, set parameters such as wall thickness, filling density and type, and convert it into a file format that can be executed by the printer;

[0061] (2) After checking whether the release film is damaged, estimate the amount of consumables and pour them into the material tank, cover it with a light-shielding layer, select the sliced ​​microfluidic model, and start printing;

[0062] (3) After printing is completed, remove the printing platform, gently peel off the printed microfluidic model, put it into an ultrasonic cleaner soaked in resin cleaning agent and wash it for 20 minutes, then take it out, wash it again with distilled water, and blow it dry for later use.

[0063] (4) After each printing, the printing platform and material tank need to be cleaned on time, and the remaining resin should be reloaded into a spare metal tank with light-shielding function.

[0064] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A sewage heavy metal ion detection device, characterized in that: Includes a sensor module and a microfluidic module; The sensor module comprises a Love wave surface acoustic wave device, the Love wave surface acoustic wave device comprises a resonance region and two Love wave interdigital transducers, the resonance region is located between the two Love wave interdigital transducers, and the resonance region is covered with a heavy metal ion adsorption film; The microfluidic module includes a microfluidic system and a Rayleigh wave surface acoustic wave device. The microfluidic system includes a dripping tank, a microfluidic channel and a waste liquid tank connected in sequence. The microfluidic channel has an experimental area overlapping with the resonance area. The Rayleigh wave surface acoustic wave device is used to drive the sewage to move from the dripping tank to the waste liquid tank.

2. A sewage heavy metal ion detection device according to claim 1, characterized in that: Valves are provided at the connection points between the microchannel, the dripping tank and the waste liquid tank.

3. A sewage heavy metal ion detection device according to claim 2, characterized in that: The microchannel is a rectangular channel with a length of 3000 μm, a width of 1000 μm and a depth of 1000 μm. The drip trough and the waste liquid trough are circular with a radius of 1785 μm and a depth of 1000 μm.

4. A sewage heavy metal ion detection device according to claim 2, characterized in that: The Rayleigh wave surface acoustic wave device comprises a mounting plate and a Rayleigh wave interdigital transducer, wherein the Rayleigh wave interdigital transducer and the drip tank are mounted on the mounting plate.

5. A sewage heavy metal ion detection device according to claim 2, characterized in that: The heavy metal ion adsorption membrane is made of cross-linked polyethylene imine dithiocarbamate polymer heavy metal ion adsorption material.

6. A sewage heavy metal ion detection device according to claim 1, characterized in that: The dripping tank, the microchannel and the waste liquid tank are made of polydimethylsiloxane material in one piece.

7. A sewage heavy metal ion detection device according to claim 1, characterized in that: The Love wave interdigital transducer adopts a delay line type interdigital transducer.

8. A sewage heavy metal ion detection device according to claim 7, characterized in that: The delay line type IDT is made of metal aluminum, has a thickness of 0.8 μm, a wavelength of 20 μm, an aperture of 1500 μm, 10 to 20 pairs of fingers, a finger width and spacing of 5 μm, and a delay distance of 2000 μm.

9. A sewage heavy metal ion detection device according to claim 1 or 5, characterized in that: The Love wave surface acoustic wave device also includes a quartz substrate and two sound absorbers. A silicon dioxide waveguide layer is provided on the quartz substrate. The Love wave interdigital transducers and the sound absorbers are mounted on the silicon dioxide waveguide layer. The two Love wave interdigital transducers are located between the two sound absorbers.

10. A sewage heavy metal ion detection device according to claim 9, characterized in that: The quartz substrate is made of ST-cut quartz with a cutting angle of 90 degrees. The thickness of the quartz substrate is 100 μm.

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