CN214150543U - Dissolved oxygen sensor - Google Patents
Dissolved oxygen sensor Download PDFInfo
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- CN214150543U CN214150543U CN202022886109.3U CN202022886109U CN214150543U CN 214150543 U CN214150543 U CN 214150543U CN 202022886109 U CN202022886109 U CN 202022886109U CN 214150543 U CN214150543 U CN 214150543U
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Abstract
The utility model relates to a dissolved oxygen sensor belongs to water environment detection technical field. Dissolved oxygen sensor contains dissolved oxygen sensor main part, four-wire cable, protective sheath, circuit board, install in the dissolved oxygen sensor main part and be used for the temperature measurement and provide temperature compensation's temperature sensor, still adopt the internal tooth of sextant pipe to be fixed with dissolved oxygen electrode, dissolved oxygen electrode contains plays airtight rubber circle to the electrode cavity to choose for use the gold sheet to make the electrode negative pole, silver makes the positive pole, and potassium chloride solution is as electrolyte solution, and organic fluoroplastics membrane is as the oxygen permeation membrane, the circuit unit of circuit board includes electrode polarization circuit, operational amplifier circuit, analog-to-digital conversion circuit, STM32F103C8T6 microcontroller, bus interface module and data memory. The utility model discloses a novel dissolved oxygen electrode structure to provide temperature compensation, improve dissolved oxygen measuring precision, degree of accuracy, sensitivity, and sensor simple structure, use and maintain the convenience.
Description
The present application is an improvement of the technical solutions described in the utility model "application date is 9/4/2020", "application number is 2020219229954", "applicant is Nanjing university of information engineering" and "invented name is a dissolved oxygen sensor", and the present application achieves better effects, and the priority of the patent is now required.
Technical Field
The utility model belongs to the technical field of the water environment detects, concretely relates to dissolved oxygen sensor.
Background
The dissolved oxygen is a concentration at which molecular oxygen in the air is dissolved in water. When the water body is polluted by organic matters and reducing substances, the concentration of dissolved oxygen is reduced, anaerobic bacteria can be propagated at the moment, the water body is deteriorated, and the concentration of dissolved oxygen can reflect the pollution degree of the water quality. Meanwhile, for the aquaculture industry, dissolved oxygen in water also has a crucial influence on the growth of fishes and the like. When the dissolved oxygen is less than 4mg/L, the fish may be killed by oxygen deficiency. Therefore, the measurement of the dissolved oxygen content of the water body has important significance for water environment protection and fishery development.
The chemical electrode method is to measure the content of dissolved oxygen by measuring the magnitude of current generated by the reaction of oxygen molecules. After oxygen molecules penetrate through the oxygen permeable membrane and enter a solution, when polarization voltage is directly applied to two electrodes of the sensor, oxidation-reduction reaction immediately occurs, electrons generated in the process form current in electrolyte, the oxygen amount penetrating through the membrane is in direct proportion to the concentration of dissolved oxygen in water, and the content of the dissolved oxygen in the water is determined by detecting the current intensity. The chemical electrode method for measuring the dissolved oxygen is easily interfered by electrode purity and various impurities in water to influence the measurement precision, the electrolyte needs to be replaced regularly, the use and the maintenance are inconvenient, and when the chemical electrode method is used for measuring the dissolved oxygen, the measurement precision is greatly influenced by temperature.
Disclosure of Invention
To utilizing dissolved oxygen sensor to measure the aquatic dissolved oxygen degree of accuracy, sensitivity not high and receive temperature to influence shortcoming such as great, the utility model provides a dissolved oxygen sensor adopts a novel dissolved oxygen electrode structure, can provide high accuracy, high sensitivity's dissolved oxygen after through temperature compensation and measure, has characteristics such as simple structure, reaction rate are fast.
In order to realize the above object, the utility model adopts the following technical scheme:
the utility model provides a dissolved oxygen sensor, contains dissolved oxygen sensor main part, four-wire cable, protective sheath, circuit board, install in the dissolved oxygen sensor main part and be used for the temperature measurement and provide temperature compensation's temperature sensor, still adopt the internal tooth of sextant to be fixed with dissolved oxygen electrode, dissolved oxygen electrode contains the rubber circle that plays airtight effect to the electrode cavity to choose the gold sheet to make electrode cathode for use, the positive pole is made to silver, and potassium chloride solution is as electrolyte solution, and organic fluoroplastics membrane is as penetrating oxygen membrane, the circuit unit of circuit board includes electrode polarization circuit, operational amplifier circuit, analog-to-digital conversion circuit, STM32F103C8T6 microcontroller, bus interface module and data memory.
Furthermore, one end of the gold sheet is welded with a lead and fixed at the bottom of the cylindrical polytetrafluoroethylene material, and the other end of the gold sheet is close to the oxygen permeation membrane.
Further, the temperature sensor is a platinum resistor.
Furthermore, the oxygen permeable membrane is fixed on the surface of the dissolved oxygen electrode by an O-shaped ring, the oxygen permeable membrane is made of one of Teflon material, polychloropropene, polyethylene or polypropylene, and the thickness of the oxygen permeable membrane is controlled within the range of 0.01-0.05 mm.
Furthermore, the dissolved oxygen sensor is made of polytetrafluoroethylene materials.
Furthermore, the circuit operation in the dissolved oxygen sensor main body is to generate 0.7V voltage through an electrode polarization circuit to realize electrochemical reaction in a dissolved oxygen electrode, an operational amplification circuit realizes operational amplification of a dissolved oxygen signal and a temperature signal, oxygen molecules enter a solution through an oxygen permeable membrane, when polarization voltage is directly applied to two electrodes of the sensor, oxidation-reduction reaction immediately occurs, electrons generated in the process form oxygen current in electrolyte, nA-level oxygen current signals generated by the electrochemical reaction are amplified through a current-to-voltage circuit consisting of a high-resistance operational amplifier, and the temperature signal is amplified through a low-power-consumption operational amplifier; the amplified dissolved oxygen signal and temperature signal are subjected to analog-to-digital conversion by an analog-to-digital conversion circuit formed by an A/D conversion chip; the oxygen current signal intensity is transmitted through a bus interface after temperature compensation is carried out by an STM32F103C8T6 microcontroller, so that the dissolved oxygen content in water is determined, and the measured data is stored in a data memory in real time.
Advantageous effects
The utility model adopts a novel dissolved oxygen electrode structure, selects a high-purity gold sheet as a cathode, can obviously reduce the residual current in the electrochemical reaction generated by the purity of the gold electrode, and improves the measurement precision and the sensitivity of the gold electrode; the temperature sensor selected by the utility model is a platinum resistor which has better detection precision and stability, is small in size and easy to fix on the main body of the dissolved oxygen sensor, is used for measuring temperature and compensating the temperature error of the dissolved oxygen content measurement, and can improve the measurement precision and accuracy; the dissolved oxygen sensor of the utility model has the advantages of simple structure, fast reaction speed and convenient use and maintenance.
Drawings
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the invention and not to limit the invention.
FIG. 1 is a front view of a dissolved oxygen electrode in the dissolved oxygen sensor of the present invention;
FIG. 2 is a structural diagram of a dissolved oxygen sensor according to the present invention;
fig. 3 is a schematic block circuit diagram of the present invention;
reference numbers in the figures: 1-dissolved oxygen sensor main body, 2-sexagesimal tube inner teeth, 3-temperature sensor, 4-rubber ring, 5-silver electrode, 6-electrolyte solution, 7-gold electrode, 8-oxygen permeable membrane, 9-O-shaped ring, 10-dissolved oxygen electrode, 11-protective sleeve and 12-four-wire cable.
Detailed Description
The present invention will be described in detail with reference to the accompanying drawings and the following detailed description.
Example 1
The utility model provides a dissolved oxygen sensor, contains dissolved oxygen sensor main part, four-wire cable, protective sheath, circuit board, install in the dissolved oxygen sensor main part and be used for the temperature measurement and provide temperature compensation's temperature sensor, still adopt the intraductal tooth of sextant to be fixed with dissolved oxygen electrode, dissolved oxygen electrode contains the rubber circle that plays airtight effect to the electrode cavity to choose the gold sheet to make the electrode negative pole for use, silver makes the positive pole, and potassium chloride solution constitutes as electrolyte and the oxygen permeable membrane that can see through the oxygen molecule, the circuit unit of circuit board includes electrode polarization circuit, operational amplifier circuit, analog-to-digital conversion circuit, STM32F103C8T6 microcontroller, bus interface module and data memory.
The temperature sensor is a platinum resistor which has better detection precision and stability, is small in size and easy to fix on the dissolved oxygen sensor main body, is used for measuring temperature and compensating for temperature errors of dissolved oxygen content measurement, and can improve the measurement precision and accuracy.
The cathode material of the dissolved oxygen electrode adopts gold. Because the gold has high catalytic activity, can not be oxidized by oxygen, can not be dissolved by the reaction of supporting electrolyte, the surface of the gold electrode is uniform and consistent, and the surface is convenient to purify, the gold electrode is used as the material of the cathode. Since the residual current in the electrochemical reaction is very closely related to the purity of the gold electrode, the higher the purity of gold, the better. After the gold sheet is polished and wiped, one end of the gold sheet is welded with a lead and fixed at the bottom of the cylindrical polytetrafluoroethylene material, and the other end of the gold sheet is close to the oxygen permeation membrane so as to promote the oxidation-reduction reaction.
The silver electrode is connected in series with the gold electrode through the electrolyte to form a passage, and the current can reach the surface of the gold electrode through the silver electrode and the electrolyte, so that the dissolved oxygen diffused to the surface of the gold electrode is ensured to generate electrochemical reaction to generate diffusion current. The silver electrode should have a larger surface area than the gold electrode to ensure that the silver electrode is sufficiently polarized. After comparison, the following method was selected to make the silver electrode: firstly, taking a section of high-purity silver wire with the diameter of 1mm and the proper length, polishing the silver wire by using 1200-mesh abrasive paper due to an oxidation layer on the silver wire, and then polishing the silver wire by using 2000-mesh abrasive paper until the surface of the electrode is bright. And then soaking the electrode in 10% ammonia water for about one hour, then washing with water, wiping with soft cloth, polishing the silver electrode, welding a lead on one end of the silver wire, winding the silver wire into a spiral shape with the diameter of 0.7cm by using a winder, and winding the spiral shape on a cylindrical polytetrafluoroethylene material.
The electrolyte configuration requires the use of high purity deionized water, and some contaminating ions can seriously affect the performance of the electrode. According to the characteristics of the dissolved oxygen electrode, the adopted supporting electrolyte is potassium chloride above an analytical grade (AR), and the potassium chloride is dissolved into a certain amount of high-purity deionized water according to a certain proportion to prepare an electrolyte solution.
The oxygen permeable membrane separates the electrolyte from the tested sample solution and is fixed on the surface of the electrode by an O-shaped ring. The selection of the membrane directly influences the response speed of the electrode, so that the oxygen permeable membrane is required to have strong permeability to oxygen molecules but cannot permeate water molecules, so that the thin film material generally adopts a Teflon material or an organic fluoroplastic membrane such as polychloropropene, polyethylene, polypropylene and the like, the thickness of the oxygen permeable membrane is generally controlled to be in the range of 0.01-0.05mm, and the thinner the oxygen permeable membrane is, the higher the sensitivity is, the thicker the oxygen permeable membrane is properly, so as to improve the toughness.
The cavity of the sensor is made of polytetrafluoroethylene materials. The diffusion current signal measured by the sensor under zero oxygen conditions is of the order nA, thus requiring an extremely high electrical insulation of the sensor cavity. The polytetrafluoroethylene has stable chemical property when working at-180 to +260 ℃ and has good electrical insulation property.
The utility model discloses the circuit unit of circuit board includes electrode polarization circuit, operational amplifier circuit, analog-to-digital conversion circuit, STM32F103C8T6 microcontroller, bus interface module and data memory. The electrode polarization circuit generates 0.7V voltage to realize electrochemical reaction in the dissolved oxygen electrode, and the operational amplification circuit mainly realizes the operational amplification of a dissolved oxygen signal and a temperature signal. After oxygen molecules penetrate through the oxygen permeable membrane and enter a solution, when polarization voltage is directly applied to two electrodes of the sensor, oxidation-reduction reaction immediately occurs, electrons generated in the process form oxygen current in electrolyte, nA-level oxygen current signals generated by electrochemical reaction firstly pass through a first-level current-to-voltage circuit composed of an operational amplifier OP37, then pass through a low-power operational amplifier AD620 for second-level amplification, and temperature signals are amplified through a low-power operational amplifier AD 627. And performing analog-to-digital conversion on the amplified dissolved oxygen signal and the amplified temperature signal, wherein a 24-bit low-noise A/D conversion chip ADS1232 is adopted by an analog-to-digital conversion circuit to ensure the measurement precision. The bus interface module selects an RS485 bus interface which is widely applied at present. The data memory stores the measured temperature and the dissolved oxygen concentration data in real time, and the practicability of the sensor is improved. The microcontroller (CPU) selects a low-power consumption STM32F103C8T6 chip, the acquired dissolved oxygen signal and temperature signal are amplified and filtered, then A/D conversion is carried out, the signals are processed by the STM32F103C8T6 microcontroller, and the measurement result is transmitted through a bus interface after temperature compensation, so that the content of the dissolved oxygen in water is measured.
The technical content of the present invention has been described above with reference to the accompanying drawings, but the scope of the present invention is not limited to the content. The technical content of the present invention can be changed by those skilled in the relevant art without departing from the spirit of the present invention, and all modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (5)
1. The utility model provides a dissolved oxygen sensor, its characterized in that contains dissolved oxygen sensor main part, four-wire cable, protective sheath, circuit board, install in the dissolved oxygen sensor main part and be used for the temperature measurement and provide temperature compensation's temperature sensor, adopt the intraductal tooth of sextant to be fixed with dissolved oxygen electrode, dissolved oxygen electrode contains plays airtight rubber circle to the electrode cavity to choose the gold sheet to make the electrode negative pole, silver is made the positive pole, and potassium chloride solution is as electrolyte solution, and organic fluorine plastic film is as penetrating oxygen membrane, the circuit unit of circuit board includes electrode polarization circuit, operational amplifier circuit, analog-to-digital conversion circuit, STM32F103C8T6 microcontroller, bus interface module and data memory.
2. The dissolved oxygen sensor of claim 1, wherein the gold sheet has one end welded with a lead wire and fixed on the bottom of the cylindrical polytetrafluoroethylene material, and the other end near the oxygen permeable membrane.
3. A dissolved oxygen sensor in accordance with claim 2, wherein said temperature sensor is a platinum resistor.
4. The dissolved oxygen sensor of claim 2, wherein the oxygen permeable membrane is fixed on the surface of the dissolved oxygen electrode by an O-shaped ring, the oxygen permeable membrane is made of one of Teflon material, polychloropropene, polyethylene or polypropylene, and the thickness of the oxygen permeable membrane is controlled within the range of 0.01-0.05 mm.
5. The dissolved oxygen sensor of claim 2, wherein the dissolved oxygen sensor is fabricated from a polytetrafluoroethylene material.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021922995 | 2020-09-04 | ||
| CN2020219229954 | 2020-09-04 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN214150543U true CN214150543U (en) | 2021-09-07 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202022886109.3U Active CN214150543U (en) | 2020-09-04 | 2020-12-03 | Dissolved oxygen sensor |
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|---|---|
| CN (1) | CN214150543U (en) |
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