CN219830933U - Electrochemical composite sensor - Google Patents
Electrochemical composite sensor Download PDFInfo
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- CN219830933U CN219830933U CN202321242793.9U CN202321242793U CN219830933U CN 219830933 U CN219830933 U CN 219830933U CN 202321242793 U CN202321242793 U CN 202321242793U CN 219830933 U CN219830933 U CN 219830933U
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- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 5
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- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
The utility model discloses an electrochemical composite sensor which is used for being placed in a solution to be detected and detecting water quality indexes, and comprises a reference electrode, a working electrode and a counter electrode, wherein the reference electrode is arranged in a salt bridge cavity, the salt bridge cavity is of a closed structure and is filled with electrolyte, and a liquid interface is arranged on the salt bridge cavity; the reference electrode is electrically connected with a signal processing circuit through a third wire, the signal processing circuit is positioned outside the salt bridge cavity, and the third wire extends out of the salt bridge cavity and is fixedly connected with the wall of the salt bridge cavity in a sealing way; the working electrode and the counter electrode are arranged outside the salt bridge cavity and are respectively and electrically connected with the signal processing circuit; the signal processing circuit is provided with a switch which can respectively control the on-off of the working electrode, the reference electrode and the counter electrode; the utility model realizes the function that the same sensor can detect different water quality indexes by utilizing different detection principles, improves the integration level of the system, simplifies the operation process and improves the detection efficiency.
Description
Technical Field
The utility model relates to the field of water quality detection, in particular to an electrochemical composite sensor.
Background
The water quality detection is often needed to judge the quality of water, for example, the quality of tap water, swimming pool water, medical wastewater and other water quality, and important parameter indexes of safety are the content of dissolved oxygen in water, the content of disinfectant, ORP value, conductivity, water temperature and the like. When the parameter indexes are detected, a composite water quality index detector is required to be used for measurement.
Then the traditional water quality detecting instrument is often provided with a plurality of water quality index sensors, and each water quality index sensor correspondingly detects a parameter index.
When carrying out multi-parameter index measurement, then need frequent change water quality index sensor, then need carry out the dismouting operation of incessantly, cause the operation process loaded down with trivial details, the condition of operating personnel inefficiency.
Therefore, it is necessary to invent an electrochemical composite sensor capable of simultaneously detecting multiple parameters of multiple water quality parameters by using the same sensor.
Disclosure of Invention
The utility model aims to provide an electrochemical composite sensor, which solves the technical problems that the traditional water quality detection sensor can only detect one water quality parameter index, and if a plurality of water quality parameter indexes are required to be measured, a plurality of sensors are required, so that the sensors are required to be frequently replaced in the measurement process, and the operation process is complicated.
In order to solve the technical problems, the utility model adopts the following technical scheme:
the utility model discloses an electrochemical composite sensor which is used for being placed in a solution to be detected and detecting water quality indexes, and comprises a reference electrode, a working electrode and a counter electrode, wherein the reference electrode is arranged in a salt bridge cavity, the salt bridge cavity is of a closed structure and is filled with electrolyte, a liquid interface is arranged on the salt bridge cavity, and the salt bridge cavity and the solution to be detected realize electronic transmission through the liquid interface;
the reference electrode is electrically connected with a signal processing circuit through a third wire, the signal processing circuit is positioned outside the salt bridge cavity, and the third wire extends out of the salt bridge cavity and is fixedly connected with the wall of the salt bridge cavity in a sealing way;
the working electrode and the counter electrode are arranged outside the salt bridge cavity and are respectively and electrically connected with the signal processing circuit, and during detection, the working electrode and the counter electrode can be in direct contact with the solution to be detected.
The working principle of the utility model is as follows: the electrochemical composite sensor can detect water quality dissolved oxygen or disinfectant (such as residual chlorine, ozone, chlorine dioxide, trichloroisocyanuric acid and the like) or ORP value or conductivity at the same time without frequently replacing a sensor probe. Specifically, when detecting a solution to be detected, immersing the salt bridge cavity, the working electrode and the counter electrode into the solution to be detected, ensuring that the liquid interface is positioned in the solution to be detected, and when detecting dissolved oxygen or disinfectant, the detection principle is based on a three-electrode ampere current method, wherein at the moment, the working electrode, the counter electrode and the reference electrode are all electrified to work, and the working electrode, the counter electrode and the reference electrode form a three-electrode measurement system; when detecting conductivity, the reference electrode is closed, the working electrode and the counter electrode form an electrode pair, and the detection principle is based on the conductivity measurement of an alternating current conductivity cell method; when ORP is detected, the counter electrode is closed, the working electrode and the reference electrode form an electrode pair, and the detection principle is based on an open circuit potential method; the electrochemical composite sensor has a three-electrode structure, can carry out adaptive on-off operation on the reference electrode and the counter electrode aiming at different detection indexes, realizes that the same sensor can detect different water quality indexes (including dissolved oxygen, disinfectant, ORP value and conductivity) by utilizing different detection principles, and avoids the technical problems of complicated operation process caused by frequent replacement of the sensor when a plurality of water quality parameter indexes are measured.
As one implementation mode of the electrochemical composite sensor, the electrochemical composite sensor comprises a shell, wherein a signal processing area and a detection area are vertically arranged in the shell, the detection area is positioned below the signal processing area, and the signal processing circuit is arranged in the signal processing area and is used for collecting and processing electric signals transmitted by the detection area;
a spacer is arranged between the signal processing area and the detection area, and the peripheral side of the spacer is fixedly and hermetically connected with the side wall inside the shell;
the salt bridge cavity is an annular salt bridge cavity and is arranged in the detection area, electrolyte is filled in the annular salt bridge cavity, the reference electrode is arranged in the annular salt bridge cavity, and the reference electrode is electrically connected with the signal processing circuit;
the bottom of the annular salt bridge cavity, which is far away from the reference electrode, is provided with a liquid interface, and a first porous material is filled in the liquid interface;
the center of the annular salt bridge cavity is provided with a circuit channel, a perforation is formed in the center of the isolation sheet corresponding to one end of the circuit channel, and the periphery of the perforation is fixedly and hermetically connected with one end of the circuit channel;
the circuit channel is internally provided with an electrode sleeve, the electrode sleeve is of a hollow structure, the electrode sleeve penetrates through the isolation sheet to enter the signal processing area and is fixedly connected with the signal processing circuit, the side wall of the other end of the electrode sleeve is provided with a working electrode and a counter electrode, the sensing surfaces of the working electrode and the counter electrode face out of the electrode sleeve and can be in direct contact with a solution to be detected in detection, and one surfaces of the working electrode and the counter electrode, which face into the electrode sleeve, are electrically connected with the signal processing circuit.
Preferably, the liquid interface is filled with a first porous material, the first porous material can delay the exudation speed of the electrolyte in the sensor, so that the sensor can work for a long time, and meanwhile, the electrolyte in the annular salt bridge cavity and the solution to be detected can be allowed to carry out electron transfer, so that the sensor can maintain a normal working state.
As a preferable scheme of the working electrode and the counter electrode, the working electrode and the counter electrode are both ring electrodes. Compared with a columnar electrode or a sheet electrode, the annular electrode has the following advantages: greater measurement response: the area of the annular electrode is larger, and the annular electrode has stronger signal transmission and response capability, so that the annular electrode can also respond faster and more sensitively to ions to be detected in a liquid sample to be detected. Lower measurement errors: for disturbing effects due to accumulation of components in the liquid at the electrode surface, the ring electrode is weaker than the cylindrical electrode or the plate electrode, and the measurement result is therefore generally more accurate and stable.
Preferably, the outer diameter range of the annular electrode is 3 mm-10 mm, the height range is 2 mm-5 mm, and the thickness range is 0.1 mm-2 mm.
Preferably, a thermistor element is further arranged in the electrode sleeve, and the thermistor element is electrically connected with the signal processing circuit and is used for measuring the temperature value of the liquid to be measured. Therefore, the electrochemical composite sensor can detect the temperature value simultaneously besides detecting the dissolved oxygen of water quality or disinfectant (such as residual chlorine, ozone, chlorine dioxide, trichloroisocyanuric acid and the like) or ORP value or conductivity, so that the detection function of the electrochemical composite sensor is more abundant.
Preferably, the signal processing circuit is electrically connected with an external cable, the external cable is located outside the shell, and the external cable is used for supplying power to the sensor circuit and transmitting data between the sensor and external equipment.
Preferably, the electrolyte filled in the annular salt bridge cavity is gel electrolyte and can be used for stabilizing the potential of the reference electrode.
Preferably, a sleeve is arranged outside the reference electrode, an opening is formed in one end of the sleeve, a second porous material is filled in the opening, and electrolyte is also filled in the sleeve. This can be more advantageous in preventing the reference electrode from being permeated into the annular salt bridge the ions of the solution to be measured in the cavity destroy the material or structure of the reference electrode itself.
The technical scheme of the utility model has the following beneficial effects: the electrochemical composite sensor disclosed by the utility model has a three-electrode structure, can carry out adaptive on-off operation on the reference electrode and the counter electrode aiming at different detection indexes, realizes that the same sensor can detect different water quality indexes (comprising dissolved oxygen, disinfectant, ORP value and conductivity) by utilizing different detection principles, and avoids the technical problems of complicated operation process caused by frequent replacement of the sensor when a plurality of water quality parameter indexes are measured; the thermistor element can be further added to realize the function that the same sensor can also measure the temperature of the solution to be measured at the same time; the electrochemical composite sensor disclosed by the utility model can improve the integration level of a system, simplify the operation process and improve the detection efficiency.
Drawings
For the purpose of making the objects, technical solutions and advantages of the present utility model more apparent, the present utility model will be described in further detail with reference to the accompanying drawings, in which:
FIG. 1 is a schematic cross-sectional view of an electrochemical composite sensor according to the present utility model.
Fig. 2 is an enlarged view of region a of fig. 1 in accordance with the present utility model.
Fig. 3 is a schematic view of the external sleeve structure of the reference electrode of the present utility model.
FIG. 4 is a schematic diagram of the operation flow of the electrochemical composite sensor during measurement according to the embodiment of the utility model.
Reference numerals illustrate: 1. a housing; 11. a signal processing section; 2. a working electrode; 21. a first wire; 3. a counter electrode; 31. a second wire; 4. a reference electrode; 41. a third wire; 42. a sleeve; 43. opening holes; 44. a second porous material; 5. a thermistor element; 51. a fourth wire; 6. an annular salt bridge cavity; 61. a wire passage; 7. a spacer; 8. a liquid interface; 81. a porous material; 9. a signal processing circuit; 10. and (5) an external connection cable.
Detailed Description
For a better understanding of the objects, structures and functions of the present utility model, an electrochemical composite sensor according to the present utility model will be described in further detail with reference to the accompanying drawings.
The utility model can be applied to detecting water quality dissolved oxygen, disinfectants (such as residual chlorine, ozone, chlorine dioxide, trichloroisocyanuric acid and the like), ORP values, electric conductivity or water temperature, and the sensor does not need to be frequently replaced when the detection index is replaced in the detection process, so that the technical problems that the traditional water quality detection sensor only can detect one water quality parameter index, and a plurality of sensors are needed when a plurality of water quality parameter indexes are needed to be measured, so that the sensor needs to be frequently replaced in the measurement process, and the operation process is complicated are solved.
Based on the technical problems solved above, as shown in fig. 1, a specific embodiment of the present utility model discloses a structural implementation manner of an electrochemical composite sensor, which is used for being placed in a solution to be detected and detecting water quality indexes, and comprises a housing 1, wherein a signal processing area 11 and a detection area are vertically arranged in the housing 1, the detection area is positioned below the signal processing area 11, and a signal processing circuit 9 is arranged in the signal processing area 11 and is used for collecting and processing electric signals transmitted by the detection area;
a spacer 7 is arranged between the signal processing area 11 and the detection area, and the peripheral side of the spacer 7 is fixedly and hermetically connected with the inner side wall of the shell 1;
an annular salt bridge cavity 6 is arranged in the detection area, electrolyte is filled in the annular salt bridge cavity 6, a reference electrode 4 is arranged in the annular salt bridge cavity 6, the reference electrode 4 is electrically connected with the signal processing circuit 9, and the reference electrode 4 is electrically connected with the signal processing circuit 9 through a third wire 41;
the bottom of the annular salt bridge cavity 6 far away from the reference electrode 4 is provided with a liquid interface 8, and the liquid interface 8 is filled with a first porous material 81;
the center of the annular salt bridge cavity 6 is provided with a circuit channel, a perforation is formed in the center of the isolating sheet 7 corresponding to one end of the circuit channel, and the periphery of the perforation is fixedly and hermetically connected with one end of the circuit channel;
an electrode sleeve 42 is arranged in the circuit channel, the electrode sleeve 42 is of a hollow structure, the electrode sleeve 42 penetrates through the isolation sheet 7 to enter the signal processing area 11 and is fixedly connected with the signal processing circuit 9, a working electrode 2 and a counter electrode 3 are arranged on the side wall of the other end of the electrode sleeve 42, the sensing surfaces of the working electrode 2 and the counter electrode 3 face out of the electrode sleeve 42 and can be in direct contact with a solution to be detected in detection, and one surfaces of the working electrode 2 and the counter electrode 3 face in the electrode sleeve 42 are electrically connected with the signal processing circuit 9.
The working principle of the specific embodiment of the utility model is as follows: the electrochemical composite sensor can detect water quality dissolved oxygen or disinfectant (such as residual chlorine, ozone, chlorine dioxide, trichloroisocyanuric acid and the like) or ORP value or conductivity at the same time without frequently replacing a sensor probe, and particularly, when the sensor detects the dissolved oxygen or disinfectant, the detection principle is based on a three-electrode amperometric method, and at the moment, the working electrode 2, the counter electrode 3 and the reference electrode 4 form a three-electrode measurement system; when detecting conductivity, the reference electrode 4 is closed, the working electrode 2 and the counter electrode 3 form an electrode pair, and the detection principle is based on an alternating current conductivity cell method for measuring conductivity; when ORP is detected, the counter electrode 3 is closed, the working electrode 2 and the reference electrode 4 form an electrode pair, and the detection principle is based on an open circuit potential method; the electrochemical composite sensor has a three-electrode structure, can carry out adaptive on-off operation on the reference electrode 4 and the counter electrode 3 aiming at different detection indexes, realizes that the same sensor can detect different water quality indexes (including dissolved oxygen, disinfectant, ORP value and conductivity) by utilizing different detection principles, and avoids the technical problems of complicated operation process caused by frequent replacement of the sensor when a plurality of water quality parameter indexes are measured.
Preferably, the electrolyte filled in the annular salt bridge cavity 6 is gel electrolyte, and can be used for stabilizing the potential of the reference electrode 4.
Specifically, the other end of the electrode sleeve 42 protrudes out of the housing 1 to facilitate contact with the solution to be measured; the electrode sleeve 42 is made of glass or a material with good electrical insulation (such as PEEK, FTFE, etc.), and the working electrode 2 and the counter electrode 3 are fixed on the side wall of the electrode sleeve 42.
Specifically, the signal processing circuit 9 is electrically connected with an external cable 10, the external cable 10 is located outside the housing 1, and the external cable is used for supplying power to the sensor circuit and transmitting data between the sensor and an external device.
In practical application, the shell 1 is made of plastic materials with stable performance and good insulation property, so as to ensure that the electrochemical weak electric signals are not disturbed.
Specifically, the surfaces of the working electrode 2 and the counter electrode 3 facing the inside of the electrode sleeve 42 are electrically connected to the signal processing circuit 9 through the first wire 21 and the second wire 31, respectively.
As a preferable embodiment of the working electrode 2 and the counter electrode 3, the working electrode 2 and the counter electrode 3 are ring electrodes. Compared with a columnar electrode or a sheet electrode, the annular electrode has the following advantages: greater measurement response: the area of the annular electrode is larger, and the annular electrode has stronger signal transmission and response capability, so that the annular electrode can also respond faster and more sensitively to ions to be detected in a liquid sample to be detected. Lower measurement errors: for disturbing effects due to accumulation of components in the liquid at the electrode surface, the ring electrode is weaker than the cylindrical electrode or the plate electrode, and the measurement result is therefore generally more accurate and stable.
In practical application, as one implementation mode of the specific dimensions of the ring electrode adopted by the working electrode 2 and the counter electrode 3, the outer diameter range of the ring electrode is 3 mm-10 mm, the height range is 2 mm-5 mm, the thickness range is 0.1 mm-2 mm, and the material adopted by the ring electrode is inert metal (such as gold or platinum) with good electric conduction.
As a preferable scheme of the electrochemical composite sensor, a thermistor element 5 is further disposed inside the electrode sleeve 42, and the thermistor element 5 is electrically connected with the signal processing circuit 9 and is used for measuring a temperature value of the liquid to be measured.
Therefore, the electrochemical composite sensor can detect the temperature value simultaneously besides detecting the dissolved oxygen of water quality or disinfectant (such as residual chlorine, ozone, chlorine dioxide, trichloroisocyanuric acid and the like) or ORP value or conductivity, so that the detection function of the electrochemical composite sensor is more abundant. Specifically, the thermistor element 5 is electrically connected to the signal processing circuit 9 through a fourth wire 51.
When measuring the temperature of the liquid to be measured, the detection principle is based on a thermistor method, and the temperature is indirectly measured by utilizing the resistance value change generated by the thermistor element 5 along with the temperature change, specifically, the thermistor element 5 refers to a resistor element made of a semiconductor material (such as oxide), and the resistance value changes along with the temperature change. Wherein a Negative Temperature Coefficient (NTC) thermistor value decreases with increasing temperature and a Positive Temperature Coefficient (PTC) thermistor value increases with increasing temperature. After the connection to the circuit by means of the thermistor element 5, the change in resistance can be measured, so that the corresponding temperature value is calculated.
As a preferred solution of the reference electrode 4, as shown in fig. 3, a sleeve 42 is disposed outside the reference electrode 4, an opening 43 is formed at one end of the sleeve 42, a second porous material 8144 is filled in the opening 43, and an electrolyte is also filled inside the sleeve 42. This can be more advantageous in preventing the reference electrode 4 from being damaged by ions of the solution to be measured penetrating into the annular salt bridge chamber 6, from damaging the material or structure of the reference electrode 4 itself.
Specifically, the working electrode 2 is one of a platinum electrode, a gold electrode, a carbon electrode, a tungsten electrode, a copper electrode and a nickel electrode.
Specifically, the counter electrode 3 is one of a silver/silver chloride electrode, a saturated calomel electrode and a platinum electrode.
Specifically, the reference electrode 4 is one of a silver/silver chloride electrode, a saturated calomel electrode, a platinum electrode, a copper/copper ion electrode and a silver/silver nitrate electrode.
Preferably, the reference electrode 4 is a silver/silver chloride electrode made of a filiform "silver/silver chloride" material.
Preferably, the liquid interface 8 is filled with a first porous material 81, and the first porous material 81 can delay the exudation speed of the electrolyte in the sensor, thereby being beneficial to the long-time operation of the sensor, and simultaneously, being capable of allowing the electrolyte in the annular salt bridge cavity 6 to carry out electron transfer with the solution to be detected, so that the sensor maintains a normal working state.
The signal processing circuit 9 comprises an MCU chip, an electronic switch, a signal generating module, a signal acquisition module, a signal amplifying module, a power supply module and an external communication module.
The MCU chip is electrically connected with the electronic switch, and can directly control the electronic switch, wherein the electronic switch is a device capable of switching a circuit switch and is used for controlling different circuits, and particularly, the electronic switch can respectively control the on-off of the working electrode 2, the reference electrode 4 and the counter electrode 3.
The signal acquisition module is electrically connected with the signal generation module, the signal amplification module is electrically connected with the signal acquisition module, and the signal generation module is used for generating specific signal waveforms or frequencies for the electric signals transmitted by the electrodes, so that the signals are acquired by the signal acquisition module, the acquired signals are transmitted to the signal amplification module, and the signal amplification module is used for amplifying the signals, so that the signals can be accurately measured and processed within a sufficient range.
The power supply module is used for providing proper direct current power supply for all elements needing power supply, including providing power supply voltage and current capable of meeting the working demands of the MCU chip and other modules, and is electrically connected with the other modules respectively.
The external communication module is used for carrying out data transmission with external equipment. The MCU chip can communicate with external modules using a digital serial interface (e.g., UART, SPI, I C, etc.). The communication needs to have corresponding protocol definition between the two parties and is realized through correct signal line connection.
The functions of switching on and off the electrodes, setting the electrode potential of the operation, collecting the current and voltage of the operation electrode 2, thereby obtaining the required measurement signals and data, etc. can be realized by the signal processing circuit 9. Each module in the signal processing circuit 9 adopts a module which is known in the prior art and can realize corresponding functions.
When dissolved oxygen and disinfectant are detected, the polarization voltage adopted by the working electrode 2 is different, specifically, when the dissolved oxygen is detected, the polarization voltage of the working electrode 2 is 500 mV-600 mV; specifically, when detecting the disinfectant, the polarization voltage of the working electrode 2 is 50 mV-200 mV.
The electrochemical composite sensor disclosed by the specific embodiment has the following technical effects: the electrochemical composite sensor disclosed by the specific embodiment has a three-electrode structure, can carry out adaptive on-off operation on the reference electrode 4 and the counter electrode 3 aiming at different detection indexes, realizes that the same sensor can detect different water quality indexes (comprising dissolved oxygen, disinfectant, ORP value and conductivity) by utilizing different detection principles, and avoids the technical problem that the sensor needs to be frequently replaced when a plurality of water quality parameter indexes are measured, so that the operation process is complicated; the thermistor element 5 can be further added to realize the function that the same sensor can also measure the temperature of the solution to be measured at the same time; the electrochemical composite sensor disclosed by the specific embodiment can improve the integration level of a system, simplify the operation process and improve the detection efficiency.
In order to further explain the structure and the working process of the electrochemical composite sensor in the present embodiment, the detection method flow of the electrochemical composite sensor in the present embodiment and the detection principle adopted for different detection indexes are described in detail.
The detection method of the electrochemical composite sensor disclosed in the specific embodiment is shown in fig. 4, and the detection method comprises the following steps:
step 1, powering up a sensor, disconnecting a working electrode 2, a counter electrode 3 and a reference electrode 4, and setting a working state as a waiting instruction;
step 2, monitoring a data instruction of external equipment, if the data instruction is received, entering step 3, otherwise, continuing to wait for the external instruction;
step 3, judging the instruction type, and entering different steps according to the instruction type;
step 4, if the dissolved oxygen is detected, the step 4 is carried out, the dissolved oxygen is detected to obtain a detection value, the detection value is specifically the current flowing through the working electrode 2, and the detection value is input into the step 9;
step 5, if the disinfectant is detected, the step 5 is carried out, the disinfectant is detected to obtain a detection value, the detection value is specifically that the current flowing through the working electrode 2 is obtained, and the detection value is input into the step 9;
step 6, if ORP detection is carried out, entering step 6, carrying out ORP detection to obtain a detection value, wherein the detection value is specifically the open circuit potential of the working electrode 2, and inputting the detection value into step 9;
step 7, if the conductivity detection is carried out, the step 7 is carried out, the conductivity detection is carried out to obtain a detection value, the detection value is specifically an alternating current signal, and the detection value is input into the step 9;
step 8, if the temperature is detected, the step 8 is carried out, the temperature is detected to obtain a detection value, the detection value is specifically a temperature value, and the detection value is input into the step 10;
step 9, the signal processing circuit 9 filters and calculates corresponding detection values in the steps through built-in slopes;
and step 10, outputting the detection value obtained in the step 9 or the step 8, and returning to the step 2 after outputting the result.
Specifically, when the dissolved oxygen is detected, the following steps are specifically included in step 4:
step 4.1: setting a working state as dissolved oxygen detection;
step 4.2: switching on the working electrode 2, the counter electrode 3 and the reference electrode 4;
step 4.3: setting polarization voltage to 500 mV-600 mV;
step 4.4: waiting for the polarization voltage to stabilize;
step 4.5: the current flowing through the working electrode 2 is sampled to obtain a current detection value.
Specifically, when the disinfectant is detected, the following contents are specifically included in step 5:
step 5.1: setting a working state as disinfectant detection;
step 5.2: switching on the working electrode 2, the counter electrode 3 and the reference electrode 4;
step 5.3: setting polarization voltage of 50 mV-200 mV;
step 5.4: waiting for the polarization voltage to stabilize;
step 5.5: the current flowing through the working electrode 2 is sampled to obtain a current detection value.
When the electrochemical compound sensor detects dissolved oxygen or disinfectant, a three-electrode amperometric method is adopted, and the working electrode 2, the counter electrode 3 and the reference electrode 4 form a three-electrode measuring system.
When dissolved oxygen or a disinfectant is detected by a three-electrode amperometric method, the working electrode 2 is brought into contact with the substance to be detected, and in the three-electrode amperometric method, an electrochemical reaction occurring thereon generates a current signal. The intensity of the current is related to the reaction between the working electrode 2 and the substance to be detected, so that the surface material and structure of the working electrode 2 have a great influence on the analysis result; the counter electrode 3 is an electrode for controlling the potential of the entire system in the circuit, and its main function is to eliminate interference in the measurement system due to the potential difference occurring between the electrode and the electrolyte, improving the measurement accuracy. The counter electrode 3 does not participate in the electrochemical reaction with respect to the working electrode 2; the reference electrode 4 is an electrode for calibrating the potential of the counter electrode 3. By being linked to the counter electrode 3, the reference electrode 4 is able to ensure that the potential of the whole system in the circuit is always in a stable state. This helps to improve the measurement accuracy and reduces the influence between the working electrode 2 and the counter electrode 3.
Specifically, when ORP detection is performed, step 6 specifically includes the following:
step 6.1: setting the working state as ORP detection;
step 6.2: switching on the working electrode 2 and the reference electrode 4, and switching off the counter electrode 3;
step 6.3: waiting for the open circuit potential to stabilize;
step 6.4: the open-circuit potential of the working electrode 2 is sampled to obtain an open-circuit potential detection value.
When the electrochemical compound sensor detects ORP, the working electrode 2 and the reference electrode 4 form an electrode pair, ORP is measured by adopting an open-circuit potential method, and when ORP (oxidation-reduction potential) is measured by adopting the open-circuit potential method, the electrochemical compound sensor is also called an electrode potential method, and the ORP reflects the potential difference between a solution to be measured and the reference electrode under standard conditions by utilizing the characteristic of half-cell reaction.
In the sensor, the working electrode 2 and the reference electrode 4 each function as follows: the working electrode 2 functions to directly contact the substance to be measured and to generate charge transfer with the reduction or oxidation reaction occurring therein. This charge transfer affects the potential difference between the electrode and the solute system according to Fick's law and is recorded. Silver/silver chloride electrodes or saturated calomel electrodes are typically used for open circuit potentiometric methods. Its function is to provide a known reference potential for comparison. When the working electrode 2 is in a contact state, the potential of the reference electrode 4 varies with a change in temperature over time, but can be accurately measured and referenced by controlling the conductivity, thereby ensuring measurement accuracy.
At the time of detecting ORP, the counter electrode 3 needs to be turned off, and if the counter electrode 3 is not turned off, there is a possibility that the sensor output is unstable and an error is increased. Specifically, when the working electrode 2 is in contact with the substance to be measured, a potential difference is generated between the working electrode 2 and the reference electrode 4. If the counter electrode 3 is not turned off, a large potential value drift or even a noise signal is generated on the sensor surface, resulting in unstable sensor output, and ORP measurement is typically based on measuring the redox capacity of the solution to be detected based on the potential difference between the working electrode 2 and the reference electrode 4, the reference electrode 4 being used to estimate the electrode latency displacement of the moving electrode. If the counter electrode 3 is not turned off, the measurement results are affected by the change in potential of the reference electrode 4 with time and temperature and oral corrosion, creating additional errors.
Specifically, in the case of conducting conductivity detection, step 7 specifically includes the following steps:
step 7.1: setting the working state as conductivity detection;
step 7.2: switching on the working electrode 2 and the counter electrode 3, and switching off the reference electrode 4;
step 7.3: starting alternating current signal output;
step 7.4: sampling the AC signal input to obtain the AC signal detection value.
When the electrochemical composite sensor detects conductivity, the working electrode 2 and the counter electrode 3 form an electrode pair, and the conductivity is measured by adopting an alternating current conductivity cell method. The alternating current conductivity cell method is based on the application of alternating current signals, and utilizes tiny voltage and current to dip into a solution to be measured, and an alternating magnetic field is measured to obtain a conductivity value representing the ion content of the solution to be measured. As the concentration of ions in the solution to be measured increases, the conductivity of the solution to be measured also increases accordingly. The working electrode 2 and counter electrode 3 in the sensor then act as follows: the working electrode 2 contacts the liquid to be tested during testing, measures the ionic conductivity of the liquid to be tested, and transmits the obtained signal to a conductivity meter for processing. The counter electrode 3 is the other electrode, which maintains a fixed potential difference in the test environment of the sensor, and the counter electrode 3 serves as a reference point for obtaining a stable potential, thereby controlling the operating conditions and eliminating noise-induced disturbances of the conductivity measurement. When detecting conductivity, the reference electrode 4 needs to be closed, if the reference electrode 4 is not closed, electrical connection can be generated between the counter electrode 3 and the reference electrode 4 in the measurement process, interference caused by the reference electrode 4 is easy to cause a measurement result, and extra errors are generated.
Specifically, during the temperature detection, step 8 specifically includes the following steps:
step 8.1: setting a water temperature detection state;
step 8.2: sampling the resistance value of the thermistor element 5;
step 8.3: and calculating a temperature value to obtain a temperature detection value.
When measuring the temperature of the liquid to be measured, the detection principle is based on a thermistor method, and the temperature is indirectly measured by utilizing the resistance value change generated by the thermistor element 5 along with the temperature change, specifically, the thermistor element 5 refers to a resistor element made of a semiconductor material (such as oxide), and the resistance value changes along with the temperature change. Wherein a Negative Temperature Coefficient (NTC) thermistor value decreases with increasing temperature and a Positive Temperature Coefficient (PTC) thermistor value increases with increasing temperature. After the connection to the circuit by means of the thermistor element 5, the change in resistance can be measured, so that the corresponding temperature value is calculated.
It will be understood that the utility model has been described in terms of specific embodiments/examples, and that various changes in and equivalents to these features and embodiments/examples may be made by those skilled in the art without departing from the spirit and scope of the utility model. Modifications to these features and embodiments/examples may be made within the teachings of the present utility model to adapt a particular situation or material to the teachings of the utility model without departing from the essential scope thereof. The embodiments/examples described herein are some, but not all embodiments/examples of the utility model. The components of the embodiments/embodiments of the present utility model generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of specific embodiments/examples of the utility model provided in the accompanying drawings is not intended to limit the scope of the utility model, as claimed, but is merely representative of selected specific embodiments/examples of the utility model. Therefore, it is intended that the utility model not be limited to the particular embodiments/examples disclosed herein, but that the particular embodiments/examples disclosed herein will include all other embodiments/examples disclosed herein as would be apparent to one skilled in the art without the benefit of this disclosure.
Claims (9)
1. The electrochemical composite sensor is characterized by comprising a reference electrode, a working electrode and a counter electrode, wherein the reference electrode is arranged in a salt bridge cavity, the salt bridge cavity is of a closed structure and is filled with electrolyte, a liquid interface is arranged on the salt bridge cavity, and the salt bridge cavity and the solution to be detected realize electronic transmission through the liquid interface;
the reference electrode is electrically connected with a signal processing circuit through a third wire, the signal processing circuit is positioned outside the salt bridge cavity, and the third wire extends out of the salt bridge cavity and is fixedly connected with the wall of the salt bridge cavity in a sealing way;
the working electrode and the counter electrode are arranged outside the salt bridge cavity and are respectively and electrically connected with the signal processing circuit, and during detection, the working electrode and the counter electrode can be in direct contact with the solution to be detected.
2. The electrochemical composite sensor according to claim 1, comprising a housing, wherein a signal processing area and a detection area are vertically arranged in the housing, the detection area is positioned below the signal processing area, and the signal processing circuit is arranged in the signal processing area and is used for collecting and processing the electric signals transmitted by the detection area;
a spacer is arranged between the signal processing area and the detection area, and the peripheral side of the spacer is fixedly and hermetically connected with the side wall inside the shell;
the salt bridge cavity is an annular salt bridge cavity and is arranged in the detection area, electrolyte is filled in the annular salt bridge cavity, the reference electrode is arranged in the annular salt bridge cavity, and the reference electrode is electrically connected with the signal processing circuit;
the bottom of the annular salt bridge cavity, which is far away from the reference electrode, is provided with a liquid interface, and a first porous material is filled in the liquid interface;
the center of the annular salt bridge cavity is provided with a circuit channel, a perforation is formed in the center of the isolation sheet corresponding to one end of the circuit channel, and the periphery of the perforation is fixedly and hermetically connected with one end of the circuit channel;
the circuit channel is internally provided with an electrode sleeve, the electrode sleeve is of a hollow structure, the electrode sleeve penetrates through the isolation sheet to enter the signal processing area and is fixedly connected with the signal processing circuit, the side wall of the other end of the electrode sleeve is provided with a working electrode and a counter electrode, the sensing surfaces of the working electrode and the counter electrode face out of the electrode sleeve and can be in direct contact with a solution to be detected in detection, and one surfaces of the working electrode and the counter electrode, which face into the electrode sleeve, are electrically connected with the signal processing circuit.
3. The electrochemical composite sensor of claim 2, wherein the fluid interface is filled with a first porous material.
4. An electrochemical composite sensor according to claim 2 or claim 3, wherein the working electrode and counter electrode are both ring electrodes.
5. The electrochemical composite sensor of claim 4, wherein the annular electrode has an outer diameter ranging from 3mm to 10mm, a height ranging from 2mm to 5mm, and a thickness ranging from 0.1mm to 2mm.
6. An electrochemical composite sensor according to claim 2 or 3, wherein a thermistor element is further arranged inside the electrode sleeve, and the thermistor element is electrically connected to the signal processing circuit and is used for measuring the temperature value of the liquid to be measured.
7. The electrochemical composite sensor of claim 6, wherein the signal processing circuit is electrically connected to an external cable, the external cable being located outside the housing.
8. The electrochemical composite sensor of claim 7, wherein the electrolyte filled inside the annular salt bridge cavity is a gel-like electrolyte.
9. An electrochemical composite sensor according to claim 2 or 3, characterized in that the reference electrode is provided externally with a sleeve, one end of which is provided with an opening, the opening is filled with a second porous material, and the interior of which is also filled with electrolyte.
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