Full-shielding structure underwater in-situ volt-ampere analyzer supporting rapid assembly and disassembly of measuring unit and method

Abstract

The invention discloses a full-shielding structure underwater in-situ volt-ampere analyzer and method supporting rapid assembly and disassembly of a measuring unit, the analyzer comprises an oil-filled cabin, a sample introduction unit and a first shielding cover are arranged in the oil-filled cabin, the sample introduction unit comprises a multi-stage filter head on the outer wall of the oil-filled cabin and a conveying pipeline communicated with the multi-stage filter head, and the conveying pipeline is communicated with a volt-ampere measuring unit; a peristaltic pump and an electromagnetic valve are arranged on the pipeline; the first shielding cover covers the inner wall of the oil filling cabin body; a volt-safety measuring unit quick mounting position is arranged on the outer wall of the oil filling cabin body; the medium oil leather bag is communicated with the oil filling cabin body and is filled with medium oil; the volt-ampere measurement unit is mounted at the quick mounting position; the pressure-resistant control cabin is connected with the oil-filled cabin, a cabin-penetrating gold-plated copper needle is arranged at the joint, and a control circuit board is arranged in the pressure-resistant control cabin; the volt-ampere measurement unit is connected with one end of the cabin-penetrating gold-plated copper needle through a shielding wire, and the other end of the cabin-penetrating gold-plated copper needle is connected with the control circuit board through a shielding wire. The volt-ampere measurement unit can be quickly disassembled and assembled, and the shielding structure improves the measurement accuracy.

Description

Technical Field

[0001] This invention relates to the field of underwater electrochemical analysis equipment technology, specifically to a fully shielded underwater in-situ voltammetric analyzer and method that supports rapid assembly and disassembly of the measurement unit, suitable for in-situ detection of trace metal ions in deep-sea environments. Background Technology

[0002] In marine environmental monitoring, in-situ and online quantification of trace metals and other pollutants in seawater is crucial. Traditional shore-based laboratory analysis relies on offshore sampling and off-site pretreatment / determination, but in ppb (μg·L⁻¹) analysis... -1 At certain concentration levels, any contact between the sample and metal components or pipelines during collection, dispensing, and transportation may introduce trace metal leaching and cross-contamination. Simultaneously, the dissolution / complexation equilibrium of elements such as Zn, Cd, Pb, Cu, Fe, and Mn is highly sensitive to pressure (depth) and temperature; changes in post-collection conditions can easily induce species transformation and concentration shifts, making it difficult to guarantee sample authenticity and introducing additional uncertainties. To overcome these limitations, there is an urgent need to develop an integrated in-situ analyzer capable of directly completing sampling, pretreatment, and voltammetric determination underwater. This would achieve low limit of detection (LOD), high accuracy, and high spatiotemporal resolution monitoring of trace heavy metals, minimizing post-collection effects and secondary contamination.

[0003] However, numerous technical challenges remain in practical underwater measurement scenarios. Firstly, due to the extremely low concentration of heavy metal ions in conventional seawater, the current obtained using the voltammetry method is at the nanoampere level. Therefore, measuring instruments deployed in marine environments are susceptible to external electromagnetic interference (EMI). For example, electromagnetic noise generated by equipment such as remotely operated vehicles (ROVs) and sonar systems can interfere with precision electrochemical sensing signals. The voltammetry method, based on the principle of detecting weak current signals, is highly sensitive to environmental electromagnetic interference. If shielding measures are inadequate, noise such as power frequency interference and stray currents from motors can easily enter the measurement circuit through coupling paths, leading to a decrease in the signal-to-noise ratio (SNR) and a deterioration in measurement accuracy. Electrochemical measurements in laboratory environments often use Faraday cages to construct electromagnetic shielding spaces to isolate external interference; related research shows that unshielded wires directly penetrating the shielding cage become a key coupling channel for power frequency interference to introduce weak signal measurement systems. However, in the miniaturization design of underwater measuring equipment, achieving such a fully enclosed electromagnetic shielding structure faces significant technical bottlenecks.

[0004] Secondly, the ease of maintenance and replacement of sensor components is crucial for long-term underwater voltammetric analyzers. Currently, the only commercially available in-situ heavy metal sensor—the Voltammetric In-Situ Profiler VIP system developed by the Italian company Idronaut—ensures that the electrode measurement unit is encased in a shielded enclosure within a cavity to guarantee effective shielding. For this type of oil-filled chamber structure, replacing or calibrating the sensor probe often presents two inconvenient solutions: one is to completely drain the oil from the chamber before replacement, a time-consuming and labor-intensive process; the other is to disassemble the sensor while the oil is still present, but this inevitably leads to oil leakage from the sensor probe into the measurement path, causing contamination. For example, some literature mentions that traditional side-mounted oil monitoring sensors inevitably leak oil at the mounting holes during replacement. This not only wastes oil and pollutes the environment but may also disrupt the instrument's internal seals and pressure balance.

[0005] Furthermore, marine observation equipment typically has specific requirements for long-term continuous operation and reduced on-site maintenance frequency. Especially in deep-sea and offshore platform scenarios, equipment recovery and frequent component replacement incur high maintenance costs. Therefore, achieving rapid, oil-free replacement of underwater sensing units has become a key research direction for improving the practicality of instruments. Based on this, developing a current-voltage measurement unit that combines external interference shielding capabilities with rapid underwater assembly and disassembly will effectively improve the performance and maintenance efficiency of underwater current-voltage analyzers, meeting the application requirements of long-term online marine monitoring. Summary of the Invention

[0006] This invention aims to overcome the shortcomings of existing underwater in-situ voltammetry analyzers, such as insufficient electromagnetic interference resistance and difficulty in replacing measurement units, and provides a fully shielded underwater in-situ voltammetry analyzer and method that supports rapid assembly and disassembly of measurement units. This analyzer enables modular and rapid assembly and disassembly of the voltammetry measurement unit without releasing oil from the oil-filled tank, and significantly improves the signal-to-noise ratio and measurement accuracy of weak underwater electrochemical current measurements through full-link shielding and single-point grounding.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A fully shielded underwater in-situ voltammetric analyzer with a structure that supports rapid assembly and disassembly of the measurement unit includes: an oil-filled tank, a medium oil bladder, a voltammetric measurement unit, and a pressure-resistant control tank. The oil-filled chamber is equipped with a sample introduction unit and a first shield. The sample introduction unit includes a multi-stage filter head, a peristaltic pump, a solenoid valve, and a delivery pipeline. The multi-stage filter head is located on the outer wall of the oil-filled chamber and is used to remove suspended particulate interference from the sample to be tested, reducing background noise and electrode surface contamination risks in voltammetry measurements. One end of the delivery pipeline is connected to the multi-stage filter head, and the other end is connected to the voltammetry measurement unit. The peristaltic pump and solenoid valve are located on the delivery pipeline. The first shield covers the inner wall of the oil-filled chamber. A quick-installation position for the voltammetry measurement unit is provided on the side wall of the oil-filled chamber. The medium oil bladder is fixedly connected to the oil-filled chamber to achieve pressure compensation, and the oil-filled chamber is filled with medium oil to achieve electrical insulation. The current-voltage measurement unit is installed in the quick-release position of the current-voltage measurement unit and is used to perform current-voltage measurement on the sample to be tested. The pressure-resistant control chamber is fixedly connected to the oil-filled chamber, and a gold-plated copper pin is provided at the fixed connection. The pressure-resistant control chamber contains an energy storage battery pack and a control circuit board. The current-voltage measuring unit is connected to one end of the gold-plated copper needle penetrating the chamber via a shielded wire, and the other end of the gold-plated copper needle penetrating the chamber is connected to the control circuit board via a shielded wire to realize data transmission.

[0008] Furthermore, the volt-ampere measurement unit includes: a volt-ampere measurement cell, a PEek inverted conical connector, a hose-hard tube connection, a working electrode, a reference electrode, and an auxiliary electrode; The structure of the volt-ampere measuring cell is divided into two functional areas: the sample flow area and the pressure balance oil seal area. The sample flow area is used for the flow, enrichment and volt-ampere measurement of the sample; the pressure balance oil seal area is used to connect with the oil-filled cavity to achieve pressure compensation and provide an electrical insulation environment. The sensing ends of the working electrode, reference electrode, and auxiliary electrode are located in the sample flow area, and their electrical connection ends are located in the pressure balance oil seal area. An O-ring is provided between the two areas for static sealing and isolation to avoid direct contact between the oil seal side medium and the seawater sample, thus eliminating the risk of cross-contamination. The PEek inverted cone connector is connected to the sample flow area of ​​the voltammetric cell, and one end of the flexible tube is connected to the PEek inverted cone connector, while the other end is connected to the delivery pipeline.

[0009] Furthermore, the volt-ampere measuring unit is connected to the quick-release position of the volt-ampere measuring unit by bolts, and a sealing ring is provided at the contact point between the volt-ampere measuring unit and the oil-filled tank.

[0010] Furthermore, the pressure-resistant control chamber is also equipped with watertight connectors and thermocouples; The watertight connector is connected to the control circuit board for external communication and synchronous control. The other end of the gold-plated copper needle that penetrates the cabin is connected to the control circuit board via a shielded wire. Specifically, it is connected to the electrode signal receiving end of the control circuit board, and the electrode signal receiving end is covered by a second shielding cover to form electromagnetic shielding. The thermocouple is used for ambient temperature monitoring and temperature compensation for volt-ampere measurement.

[0011] Furthermore, the oil-filled chamber includes an oil-filled cavity and oil-filled cavity end caps and a first connecting end cap respectively disposed at both ends of the oil-filled cavity; the multi-stage filter head is disposed on the oil-filled cavity end cap, and the quick-release position of the volt-ampere measurement unit is opened on the oil-filled cavity; The pressure-resistant control chamber includes a pressure-resistant control cavity and a second connecting end cover and a temperature measuring end cover respectively located at both ends of the pressure-resistant control cavity; the watertight connector and the thermocouple are located on the temperature measuring end cover; The first connecting end cap and the second connecting end cap are fixedly connected by threads to realize the connection between the oil-filled tank and the pressure-resistant control tank.

[0012] Furthermore, the peristaltic pump adopts an in-pipe flow structure, so that the sample to be tested only contacts the inner surface of the delivery pipeline, effectively avoiding potential metal leaching or cross-contamination of the sample to be tested by other components of the pump body.

[0013] Furthermore, the medium oil is silicone oil, the delivery pipeline is made of PTFE or FEP, and the gold-plated copper needles penetrating the compartment are sealed and fixed with epoxy resin.

[0014] The measurement method using the fully shielded underwater in-situ voltammetry analyzer with a rapid assembly and disassembly of the measurement unit as described in any one of the claims includes the following steps: 1) Pre-install the volt-ampere measurement unit in the quick-installation position of the volt-ampere measurement unit, and place the underwater in-situ volt-ampere analyzer in the test water body; 2) The control circuit board reads the thermocouple to complete the self-test and temperature compensation settings; and controls the solenoid valve to open the delivery pipeline, start the peristaltic pump, extract the sample to be tested from the test water body and send it into the voltammetry measurement cell through a multi-stage filter head; after reaching the set volume and residence time, it executes the enrichment, settling and scanning sequence, collects the current / potential data of the working electrode, reference electrode and auxiliary electrode to the control circuit board, and transmits the measurement data back to the computer through the watertight connector; after the measurement is completed, it enters the next measurement cycle or standby.

[0015] Furthermore, when it is necessary to replace the volt-ampere measuring unit, make the quick-release opening of the volt-ampere measuring unit face upward, remove the volt-ampere measuring unit and replace it with a new volt-ampere measuring unit.

[0016] Compared with the prior art, the beneficial effects of the present invention are: Significantly improved maintainability: By installing a quick-install and removable volt-ampere measurement unit on the side wall of the oil-filled chamber, rapid replacement on water is achieved without the need for draining oil, vacuuming, or refilling oil, effectively shortening the maintenance cycle and reducing operational complexity and environmental risks.

[0017] Enhanced electromagnetic interference resistance: The fully shielded structure and single-point grounding strategy are adopted, and a shielding continuity is established between the three electrodes (working electrode, reference electrode and auxiliary electrode), the shielding cover, the shielding wire, the gold-plated copper needle through the tank, and the control circuit board. This can effectively suppress common-mode / differential-mode interference in long cable power supply, pump and valve drive and seawater environment, and significantly improve the signal-to-noise ratio and measurement stability of weak current volt-ampere signals.

[0018] Improved sample authenticity and measurement accuracy: Multi-stage filter head and in-tube flow path design reduce interference introduced by particle and metal leaching; The sample flow area and pressure balance oil seal area of ​​the voltammetric cell are effectively isolated by O-ring seals to avoid direct contact between the oil seal medium and the sample, eliminating cross-contamination at the source; The enrichment-voltammetric determination process is completed in situ, reducing deviations caused by post-collection morphological changes and secondary contamination.

[0019] High engineering adaptability: The modular measurement unit quick-installation structure facilitates rapid replacement and upgrading of different electrode types and measurement ranges, meeting the needs of multi-scenario sea trials and long-term deployment.

[0020] Corrosion-resistant and low-emission fluid connection system: Peek inverted tapered joints and hoses / rigid pipes are connected in a straight line with inert pipes made of PTFE or FEP material to form a seawater-resistant flow path with low adsorption and low emission, which takes into account pressure resistance, sealing and quick assembly, and reduces leakage and dead volume.

[0021] Temperature measurement and compensation link: The temperature measuring end cap has a built-in thermocouple that provides real-time temperature input to the control circuit board for temperature compensation and threshold correction of voltammetry measurement, reducing the impact of ambient temperature changes on dissolution / enrichment kinetics and electrode potential.

[0022] Highly reliable through-tank electrical connection and sealing: The gold-plated copper through-tank pin is sealed with epoxy resin, which has low contact resistance, pressure resistance and corrosion resistance. It also serves as a reliable junction point for the shield / ground circuit, improving the overall machine's resistance to environmental stress. This structure has been proven by hydrostatic pressure testing to be usable in water depths of up to 4500m. Voltage stabilization and insulation: By filling the oil-filled cavity with medium oil and setting a medium oil bladder connected to the oil-filled cavity, the pressure inside the oil-filled cavity changes synchronously with the external sea pressure, ensuring the normal operation of the sample injection unit, and the medium oil has a good insulation effect. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of one embodiment of the present invention; Figure 2 This is a schematic diagram of the structure from another direction of one embodiment of the present invention; Figure 3 This is a schematic diagram of the pressure-resistant control chamber structure according to an embodiment of the present invention; Figure 4 This is a schematic diagram of an oil-filled tank structure according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the structure of a current-ampere measuring unit according to an embodiment of the present invention; Figure 6 This is a schematic diagram showing the results of three seawater measurements according to an embodiment of the present invention; In the diagram: 1. Watertight connector; 2. Pressure-resistant control chamber; 3. Oil-filled chamber; 4. Medium oil bladder; 5. Temperature measuring end cap; 6. Thermocouple; 7. Pressure-resistant control chamber; 8. Circuit board mounting disc; 9. Control circuit board; 10. Mounting plate; 11. Energy storage battery pack; 12. First connecting end cap; 13. Gold-plated copper needle penetrating the chamber; 14. Multi-stage filter head; 15. Voltmeter-ampere measuring unit; 16. Oil-filled chamber; 17. First shielding cover; 18. Oil-filled chamber end cap; 19. Medium oil bladder adapter; 20. Support component; 21. Peristaltic pump; 22. Peristaltic pump mounting plate; 23. Two-position three-way solenoid valve; 24. Solenoid valve mounting plate; 25. Voltmeter-ampere measuring cell; 26. PEEK inverted conical connector; 27. Flexible hose / rigid tube connection straight connector; 28. Working electrode; 29. ​​Reference electrode; 30. Auxiliary electrode; 31. Second connecting end cap. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] According to a specific embodiment of the present invention, a fully shielded underwater in-situ voltammetry analyzer with a measurement unit that supports rapid assembly and disassembly includes: an oil-filled tank 3, a medium oil bladder 4, a voltammetry measurement unit 15, and a pressure-resistant control tank 2. The oil-filled chamber 3 is equipped with a sample introduction unit and a first shield 17. The sample introduction unit includes a multi-stage filter head 14, a peristaltic pump 21, a solenoid valve, and a delivery pipeline. The multi-stage filter head 14 is located on the outer wall of the oil-filled chamber 3. One end of the delivery pipeline is connected to the multi-stage filter head 14, and the other end is connected to the volt-ampere measurement unit 15. The peristaltic pump 21 and the solenoid valve are located on the delivery pipeline. The first shield 17 covers the inner wall of the oil-filled chamber 3. A quick-installation position for the volt-ampere measurement unit is provided on the side wall of the oil-filled chamber. The medium oil bladder 4 is fixedly connected to the oil-filled tank 3, and the oil-filled tank 3 and the medium oil bladder 4 are filled with medium oil. The current-ampere measurement unit 15 is installed in the quick-release position of the current-ampere measurement unit and is used to perform current-ampere measurement on the sample to be tested. The pressure-resistant control chamber 2 is fixedly connected to the oil-filled chamber 3. A gold-plated copper pin 13 is provided at the fixed connection. The pressure-resistant control chamber 2 is equipped with an energy storage battery pack 11 and a control circuit board 9. The current-voltage measuring unit 15 is connected to one end of the gold-plated copper needle 13 through the chamber via a shielded wire, and the other end of the gold-plated copper needle 13 through the chamber is connected to the control circuit board 9 via a shielded wire to realize data transmission.

[0026] Example: 1. Overall Structure Please see Figure 1-5 The present invention provides a fully shielded underwater in-situ voltammetric analyzer that supports rapid assembly and disassembly of the measurement unit. The analyzer is generally composed of a pressure-resistant control chamber 2 and an oil-filled chamber 3 that is laterally fixedly connected to it.

[0027] The pressure-resistant control chamber 2 contains, in sequence, a circuit board mounting disc 8, a control circuit board 9, a mounting plate 10, and an energy storage battery pack 11. The front end of the pressure-resistant control chamber 2 is threadedly sealed to the first connecting end cover 12 of the oil-filled chamber 3 via a second connecting end cover 31. Eleven gold-plated copper pins 13 are fixed to the second connecting end cover 31 as power and signal channels. A watertight connector 1 is installed on the outside of the pressure-resistant control chamber 2 for external communication and synchronous control. The other end of the pressure-resistant control chamber 2 is a temperature measuring end cover 5, within which thermocouples 6 are arranged for temperature compensation during ambient temperature monitoring and volt-ampere measurement.

[0028] The oil-filled chamber 3 is filled with silicone oil and is equipped with a dielectric oil bladder 4 and its adapter 19 to achieve external pressure compensation. The oil-filled chamber 3 includes an oil-filled cavity 16 and first connecting end caps 12 and oil-filled cavity end caps 18 respectively mounted at its two ends. A quick-installation position for the volt-ampere measurement unit 15 is opened on the side wall of the oil-filled cavity 16. To achieve electromagnetic shielding continuity, a first shielding cover 17 is set inside the oil-filled chamber 3. The side wall of the first shielding cover 17 is only provided with limiting holes for the working electrode 28, reference electrode 29, and auxiliary electrode 30 of the volt-ampere measurement unit 15 to pass through the internal pipeline, minimizing gap coupling and radiation leakage. With the help of shielded wire transition, the coupling of electromagnetic interference to the high impedance node at the front end is reduced.

[0029] Regarding the fluid actuators, the oil-filled tank 3 is equipped with multi-stage filter heads 14, a peristaltic pump 21, and solenoid valves, among which the solenoid valves are two-position three-way solenoid valves 23; correspondingly, there are peristaltic pump mounting plates 22 and solenoid valve mounting plates 24, as well as support components 20 for load bearing and vibration resistance. The fluid connection adopts a PEEK inverted tapered connector 26 and a hose-hard pipe butt joint straight connector 27 to achieve corrosion resistance, low precipitation, and reliable sealing.

[0030] 2. Fluid path and measuring cell structure Seawater samples are filtered through a multi-stage filter head 14 via the inlet and then enter a peristaltic pump 21 via a delivery pipeline. The peristaltic pump 21 employs an in-pipe flow path design to ensure that the sample only contacts the pump pipe, preventing metal leaching from the pump components. After the peristaltic pump 21, a two-position three-way solenoid valve 23 switches between different delivery pipelines in the voltammetric cell 25 to control the timing of sample entry. Finally, the delivery pipeline connects to the flexible hose / rigid hose connection 27, which in turn connects to the PEek inverted conical connector 26, thus introducing the sample into the voltammetric cell 25. Preferably, the peristaltic pump 21 has a volumetric flow rate set to 2 mL / min, adjustable within the range of 0.1–8 mL / min to accommodate different enrichment times and noise control requirements.

[0031] All fluid nodes are connected using PEEK inverted conical connectors 26 and hose / rigid pipe straight connectors 27. The preferred pipe material is PEEK / PTFE / FEP to reduce adsorption and precipitation. Waste liquid is discharged or collected through separate pipes.

[0032] The voltammetric cell 25 is divided into two parts: a sample flow area and a pressure balance oil seal area. Sample flow area: The induction section (immersion section) of the working electrode 28, reference electrode 29, and auxiliary electrode 30 is set to realize sample enrichment and voltammetry testing; Pressure balancing oil seal area: It is connected to the oil-filled cavity 16 and filled with silicone oil, serving as an electrical insulation and pressure compensation cavity for the electrode leads and interfaces.

[0033] The two areas are statically sealed and isolated using O-rings to prevent direct contact between silicone oil and seawater samples, thus preventing cross-contamination. The electrical connection terminals of the three electrodes (working electrode 28, reference electrode 29, and auxiliary electrode 30) in the voltammetric cell 25 are connected to the oil-filled chamber 16, which in turn is connected to the medium oil bladder 4. This ensures that the pressure within the oil-filled chamber changes synchronously with the external sea pressure, guaranteeing the normal operation of the peristaltic pump 21. Piping holes are pre-drilled on both sides of the voltammetric cell 25 to facilitate the orderly arrangement and stress release of sample waste liquid pipelines and rinsing pipelines. A detachable, sealed connection is achieved between the voltammetric cell 25 and the oil-filled chamber 16 using a four-bolt + two-ring structure. This design allows for modular disassembly and assembly without releasing the silicone oil inside the chamber when the quick-release position of the voltammetric unit is facing upwards, significantly shortening maintenance time and reducing secondary contamination and sealing risks.

[0034] 3. Electrical connections, shielding and grounding The electrode signal receiving end of the control circuit board 9 is partially covered by a second shield to form a Faraday cage. The shield 17 is connected to the signal ground of the control circuit board 9 at a single point via a gold-plated copper pin 13. The leads of the three electrodes (working electrode 28, reference electrode 29, and auxiliary electrode 30) use shielded wires and are connected to the control circuit board 9 via the first shield 17 and the gold-plated copper pin 13. The communication circuit corresponding to the watertight connector 1 adopts a star-shaped single-point grounding strategy with the housing to suppress common-mode and differential-mode interference. If necessary, a π-type filter and a common-mode choke are arranged at the through-cell location to further improve the signal-to-noise ratio of weak current measurement. The thermocouple 6 signal is isolated / filtered and then input to the control circuit board 9 for temperature compensation in volt-ampere measurement.

[0035] 4. Sealing and pressure compensation The first connecting end cap 12, the second connecting end cap 31, the pressure-resistant control chamber 7, the oil-filled chamber 16 and its oil-filled chamber end cap 18, and the volt-ampere measuring unit 15 and the oil-filled chamber 16 are all provided with two sealing grooves and equipped with O-rings made of FKM or FFKM material at their connection surfaces. The medium oil bladder 4 is connected to the oil-filled chamber 16 through the medium oil bladder adapter 19 to form an isobaric compensation system that changes with the external sea pressure. The gold-plated copper needle 13 penetrating the tank is sealed and fixed with epoxy resin to ensure electrical insulation and sealing reliability under high pressure.

[0036] 5. Assembly and Maintenance 1) The volt-ampere measuring unit 15 is pre-installed in the quick-install position of the volt-ampere measuring unit in the oil-filled cavity 16; 2) Arrange and tighten the PEek tapered connector 26 and the hose / rigid tube connection 27 to complete the sample tubing connection; 3) Connect the leads of the three electrodes (working electrode 28, reference electrode 29 and auxiliary electrode 30) to the shielded wires led out from the gold-plated copper needle 13 through the limiting hole of the first shield 17. 4) Assemble the oil-filled tank end cap 18 and confirm that the medium oil bladder 4 and the medium oil bladder adapter 19 are smoothly connected; 5) Connect the first connecting end cap 12 to the second connecting end cap 31 on the pressure control chamber 2 to complete the final assembly, and dock with the watertight connector 1 to perform a communication self-test.

[0037] When the volt-ampere measuring unit 15 needs to be replaced, with the quick-release opening of the volt-ampere measuring unit facing upwards, loosen the four external bolts, remove the volt-ampere measuring unit 15, and replace it with a component of the same specification. The delivery pipeline will not be contaminated during the replacement process. During this process, the silicone oil in the oil-filled chamber 3 does not need to be drained, and the medium oil bladder 4 and the medium oil bladder adapter 19 remain connected, achieving rapid restoration. After replacement, reset the components in the above sequence and verify the sealing and electrical performance.

[0038] 6. Work Process After power-on, the control circuit board 9 reads the thermocouple 6 and internal pressure signals to complete self-testing and temperature / pressure compensation settings; it then controls the two-position three-way solenoid valve 23 to switch to the set measurement channel, and starts the peristaltic pump 21 to send the sample through the multi-stage filter head 14 into the voltammetric cell 25 at a rate of 2 mL / min; after reaching the set volume and residence time, it executes the enrichment, settling, and scanning sequence (such as DPASV / SWV / LSV) to collect the current / potential data of the three electrodes (working electrode 28, reference electrode 29, and auxiliary electrode 30); after the measurement is completed, it enters the next cycle or standsby. Throughout the process, the continuous shielding of the first shield 17 and the shell, along with single-point grounding, ensures the anti-interference capability of high-impedance micro-current signals. Figure 6 The image shows three measurements of the same seawater sample by a fully shielded underwater in-situ voltammetry analyzer with a quick-release structure for the measurement unit, provided by the present invention. It can be seen that the three measurement results are basically the same, indicating that replacing the voltammetry measurement unit 15 with the quick-release voltammetry measurement unit has virtually no impact on the measurement results, and the device has good test stability.

[0039] 7. Optimal Selection of Materials and Parameters The preferred material for the housing is titanium alloy; the preferred materials for the electrode support and fluid connector are PEEK; the preferred materials for the seals are FKM / FFKM; the preferred materials for the delivery piping are PTFE / FEP; the preferred material for the solenoid valve is a high-pressure resistant two-position three-way valve; and the preferred material for the peristaltic pump 21 hose is a low-exudation, anti-swelling material. The surface roughness of all mating surfaces is preferably Ra≤1.6 μm to ensure sealing performance. It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fully shielded underwater in-situ voltammetric analyzer with a structure supporting rapid assembly and disassembly of the measurement unit, characterized in that, include: Oil-filled tank, medium oil bladder, volt-ampere measurement unit, and pressure-resistant control tank; The oil-filled chamber is equipped with a sample introduction unit and a first shield. The sample introduction unit includes a multi-stage filter head, a peristaltic pump, a solenoid valve, and a delivery pipeline. The multi-stage filter head is located on the outer wall of the oil-filled chamber. One end of the delivery pipeline is connected to the multi-stage filter head, and the other end is connected to the volt-ampere measurement unit. The peristaltic pump and the solenoid valve are located on the delivery pipeline. The first shield covers the inner wall of the oil-filled chamber. A quick-installation position for the volt-ampere measurement unit is provided on the side wall of the oil-filled chamber. The medium oil bladder is fixedly connected to the oil-filled tank, and the oil-filled tank and the medium oil bladder are filled with medium oil. The current-voltage measurement unit is installed in the quick-release position of the current-voltage measurement unit and is used to perform current-voltage measurement on the sample to be tested. The pressure-resistant control chamber is fixedly connected to the oil-filled chamber, and a gold-plated copper pin is provided at the fixed connection. The pressure-resistant control chamber contains an energy storage battery pack and a control circuit board. The current-voltage measuring unit is connected to one end of the gold-plated copper needle penetrating the chamber via a shielded wire, and the other end of the gold-plated copper needle penetrating the chamber is connected to the control circuit board via a shielded wire to realize data transmission.

2. The underwater in-situ voltammetric analyzer according to claim 1, characterized in that, The current-voltage measurement unit includes: a current-voltage measurement cell, a PEek inverted conical connector, a hose-hard tube connection, a working electrode, a reference electrode, and an auxiliary electrode; The structure of the volt-ampere measuring cell is divided into a sample flow area and a pressure balance oil seal area. The sample flow area is used for the flow, enrichment and volt-ampere measurement of the sample. The pressure balance oil seal area is connected to the oil-filled cavity to achieve pressure compensation and provide an electrical insulation environment. The sensing ends of the working electrode, reference electrode and auxiliary electrode are located in the sample flow area, and their electrical connection ends are located in the pressure balance oil seal area. An O-ring is provided between the two areas. The PEek inverted cone connector is connected to the sample flow area of ​​the voltammetric cell, and one end of the flexible tube is connected to the PEek inverted cone connector, while the other end is connected to the delivery pipeline.

3. The underwater in-situ voltammetric analyzer according to claim 2, characterized in that, The volt-ampere measuring unit is connected to the quick-release position of the volt-ampere measuring unit by bolts, and an O-ring is provided at the contact point between the volt-ampere measuring unit and the oil-filled tank.

4. The underwater in-situ voltammetric analyzer according to claim 1, characterized in that, The pressure-resistant control chamber is also equipped with watertight connectors and thermocouples. The watertight connector is connected to the control circuit board for external communication and synchronous control. The other end of the gold-plated copper needle that penetrates the cabin is connected to the control circuit board via a shielded wire. Specifically, it is connected to the electrode signal receiving end of the control circuit board, and the electrode signal receiving end is covered by a second shielding cover to form electromagnetic shielding. The thermocouple is used for ambient temperature monitoring and temperature compensation for volt-ampere measurement.

5. The underwater in-situ voltammetric analyzer according to claim 4, characterized in that, The oil-filled chamber includes an oil-filled cavity and oil-filled cavity end caps and a first connecting end cap respectively located at both ends of the oil-filled cavity; the multi-stage filter head is located on the oil-filled cavity end cap, and the quick-release position of the volt-ampere measurement unit is located on the oil-filled cavity; The pressure-resistant control chamber includes a pressure-resistant control cavity and a second connecting end cover and a temperature measuring end cover respectively located at both ends of the pressure-resistant control cavity; the watertight connector and the thermocouple are located on the temperature measuring end cover; The first connecting end cap and the second connecting end cap are fixedly connected by threads to realize the connection between the oil-filled tank and the pressure-resistant control tank.

6. The underwater in-situ voltammetric analyzer according to claim 1, characterized in that, The peristaltic pump adopts an in-pipe flow structure, so that the sample to be tested only contacts the inner surface of the delivery pipeline.

7. The underwater in-situ voltammetric analyzer according to claim 1, characterized in that, The medium oil is silicone oil, the conveying pipeline is made of PTFE or FEP, and the gold-plated copper needles penetrating the compartment are sealed and fixed with epoxy resin.

8. A measurement method using a fully shielded underwater in-situ voltammetry analyzer with a rapid assembly and disassembly of the measurement unit as described in any one of claims 1-7, characterized in that... Includes the following steps: 1) Pre-install the volt-ampere measurement unit in the quick-installation position of the volt-ampere measurement unit, and place the underwater in-situ volt-ampere analyzer in the test water body; 2) The control circuit board reads the thermocouple to complete the self-test and temperature compensation settings; and controls the solenoid valve to open the delivery pipeline, start the peristaltic pump, extract the sample to be tested from the test water body and send it into the voltammetry measurement cell through a multi-stage filter head; after reaching the set volume and residence time, it executes the enrichment, settling and scanning sequence, collects the current / potential data of the working electrode, reference electrode and auxiliary electrode to the control circuit board, and transmits the measurement data back to the computer through the watertight connector; after the measurement is completed, it enters the next measurement cycle or standby.

9. The method according to claim 8, characterized in that, When it is necessary to replace the volt-ampere measuring unit, make the quick-release opening of the volt-ampere measuring unit face upward, remove the volt-ampere measuring unit and replace it with a new volt-ampere measuring unit.

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