CN114264637A - Dissolved oxygen real-time online monitoring sensor device, control method and use method - Google Patents

Dissolved oxygen real-time online monitoring sensor device, control method and use method Download PDF

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CN114264637A
CN114264637A CN202111570827.2A CN202111570827A CN114264637A CN 114264637 A CN114264637 A CN 114264637A CN 202111570827 A CN202111570827 A CN 202111570827A CN 114264637 A CN114264637 A CN 114264637A
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signal
light source
led light
dissolved oxygen
sensor device
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李邦义
孙志浩
戴嘉玥
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Hangzhou Jinge Technology Co ltd
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Hangzhou Jinge Technology Co ltd
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Abstract

The invention discloses a dissolved oxygen real-time online monitoring sensor device, which comprises an optical probe, a photoelectric conversion unit and a signal processing unit, wherein an optical part comprises a shell, a fluorescent film and a protective layer, a hollow cavity is arranged in the shell, an optical window is arranged on the shell, one side of the shell, which is provided with the optical window, is the front side, and otherwise, the fluorescent film is coated on the front surface of the optical window; the surface of the fluorescent film is covered with a protective layer for shading light and avoiding water body pollution; the photoelectric conversion unit is arranged in the hollow cavity of the shell and comprises a blue LED light source serving as an excitation light source, a red LED light source serving as a reference light source, a photoreceptor and a red filter; the signal processing circuit comprises an analog circuit device and a digital-to-analog conversion device, wherein the analog circuit device comprises an analog power supply and a digital power supply; the invention also discloses a control method and a using method of the dissolved oxygen real-time online monitoring sensor device. The invention has the beneficial effects that: short response time, stable signal value, good reversibility and high stability.

Description

Dissolved oxygen real-time online monitoring sensor device, control method and use method
Technical Field
The invention belongs to the field of monitoring of dissolved oxygen in water, and relates to a dissolved oxygen real-time online monitoring sensor device, a control method and a use method.
Background
With the development of society and science and technology, people have entered an information age, and the demand of people for various data information is more urgent, because the data information is closely related to the aspects of the quality of life, the development of productivity, scientific research, national economy and even national safety and the like of people, the innovative development of the dissolved oxygen detection technology has profound significance.
Molecular oxygen dissolved in water is called dissolved oxygen, and the content of dissolved oxygen in water is closely related to the partial pressure of oxygen in air, the temperature of water, and the like. The amount of dissolved oxygen in water is an important index for measuring the cleanness degree of water. The determination of the content of dissolved oxygen in water is of great significance to the fields of environmental monitoring, aquaculture, industrial production, medical treatment and health care and the like.
At present, various technologies for measuring dissolved oxygen are available at home and abroad, and the traditional methods include iodometry, spectrophotometry, gas chromatography, colorimetric visual inspection, electrode method and the like. These conventional measurement methods have their own rationales but all suffer from some drawbacks. For example, the iodometry method is suitable for detecting the dissolved oxygen in the water body in a laboratory, but has the problems of complex operation, long time consumption, incapability of realizing real-time online detection and the like; the electrode method consumes the dissolved oxygen in the water body when detecting the dissolved oxygen in the water body, has larger measurement error, is easy to age the electrode and the oxygen permeable membrane, needs to continuously replace the gas permeable membrane, and has the problem of complex maintenance process; the gas chromatography is used for quickly and accurately measuring the concentration of dissolved oxygen in the water body, but the gas chromatography is difficult to popularize on a large scale. The dissolved oxygen real-time monitoring sensor based on the fluorescence quenching principle has the advantages of no consumption of dissolved oxygen in water, high sensitivity, high measurement accuracy and the like, meets the real-time online monitoring requirement of the concentration of the dissolved oxygen in the water at present, and better accords with the current research direction of the dissolved oxygen detection.
The fluorescence quenching principle refers to the phenomenon that oxygen molecules can enable a specific fluorescent substance to generate a fluorescence quenching effect, and the fluorescent substance and quencher molecules act to reduce the fluorescence intensity and the service life of the fluorescent molecules, so that the dissolved oxygen content is measured by virtue of the two intrinsic parameters. Common fluorescence quenchers include halogen ions, heavy metal ions, oxygen molecules, nitro compounds, diazo compounds, carboxyl compounds, carbonyl compounds and the like. Oxygen is a natural quencher for some phosphors, and the oxygen quenching process has been demonstrated to be dynamic quenching, which is based on the energy transfer that occurs after the oxygen collides with the excited phosphor, thereby causing a decrease in fluorescence intensity. However, after the collision, the two are separated immediately, and the fluorescent molecule is not chemically changed, so that the quenching of the fluorescent molecule by oxygen is reversible. The measurement of dissolved oxygen content can be roughly divided into three processes — an absorption process, a fluorescence process, and a quenching process. The dynamic quenching process conforms to the Stern-Volmer equation, and the quenching degree of the fluorescent substance is positively correlated with the oxygen concentration. But now existing
Various dissolved oxygen measuring methods are comprehensively compared, and the dissolved oxygen sensor based on the fluorescence quenching principle is free from the defects and has numerous advantages: the device does not consume dissolved oxygen of the water body in the measurement process, does not need to consider the flowing speed and the stirring speed of the water body, resists electromagnetic interference, does not need a reference electrode, is small and portable, is simple and convenient to operate, can realize remote, continuous and on-line monitoring and the like, and has better application prospect.
Disclosure of Invention
In order to solve the problems, the invention provides a dissolved oxygen real-time online monitoring sensor device, a control method and a using method.
In order to meet the requirements, the invention is realized by the following technical scheme:
the invention relates to a dissolved oxygen real-time on-line monitoring sensor device, which is characterized in that: the optical probe comprises a shell, a fluorescent film and a protective layer, wherein a hollow cavity is arranged in the shell, an optical window through which light can pass is arranged on the shell, the side of the shell, on which the optical window is arranged, is the front side, and otherwise, the fluorescent film is coated on the front surface of the optical window; the surface of the fluorescent film is covered with a protective layer for shading light and avoiding water body pollution;
the photoelectric conversion unit is arranged in the hollow cavity of the shell and comprises a blue LED light source serving as an excitation light source, a red LED light source serving as a reference light source, a photoreceptor, a red optical filter and an I/V converter, wherein the blue LED light source and the red LED light source are respectively arranged on two opposite sides of the hollow cavity of the shell, and the light emitting directions of the blue LED light source and the red LED light source are simultaneously aligned to the central area of the fluorescent film, so that the fluorescent film is positioned at the focuses of the blue LED light source and the red LED light source; the photoreceptor is arranged in a hollow cavity of the shell right behind the fluorescent film, and a fluorescent signal output end of the photoreceptor is connected with a fluorescent signal input end circuit of the signal processing part and used for transmitting a received fluorescent signal to the signal processing part; the red light filter is arranged between the fluorescent film and the photoreceptor and is used for eliminating the interference of stray light on the photoreceptor so as to selectively transmit light of a specific waveband; the signal output end of the I/V converter is electrically connected with the signal input end of the signal processing circuit and is used for converting a current signal into a voltage signal;
the signal processing circuit comprises an analog circuit device and a digital-to-analog conversion device, the analog circuit device comprises an analog power supply and a digital power supply, the analog power supply and the digital power supply are physically isolated and respectively provided with an independent ground wire and a power supply, and the analog power supply is respectively and electrically connected with the light sensor, the driving end of the blue LED light source and the driving end of the red LED light source through the analog circuit and is used for controlling the sensor equipment to work; the digital power supply is respectively and electrically connected with the photoreceptor, the driving end of the blue LED light source and the driving end of the red LED light source through a microcontroller, and the digital power supply is in signal connection with external storage equipment through an I/O interface circuit and is used for monitoring and controlling the sensor device in real time.
Further, the digital power supply comprises a power supply, an LED driving chip, a photoelectric converter, an alternating current amplification filtering unit, a microcontroller and a signal processing and transmitting unit;
the power transmission end of the power supply is respectively and electrically connected with the LED driving chip, the photoelectric converter, the I/V converter, the alternating current amplification filtering unit and the phase detection unit;
the optical signal input end of the photoelectric converter is electrically connected with the optical signal output end of the sensor, and the current signal output end of the photoelectric converter is electrically connected with the electrical input end of the I/V converter and is used for converting an optical signal into a current signal and transmitting the current signal to the I/V converter;
the signal output end of the I/V converter is electrically connected with the signal input end of the alternating current amplification filtering unit and is used for converting a current signal into a voltage signal;
and the signal output end of the alternating current amplification filtering unit is electrically connected with the signal input end of the microcontroller and is used for carrying out square wave modulation on the voltage signal to obtain a corresponding square wave signal.
The control end of the microcontroller is electrically connected with the drive end of the blue LED light source and the red LED light source through an LED drive chip and is used for controlling the blue LED light source and the red LED light source to work; the microcontroller is internally provided with a phase detection unit, the signal input end of the phase detection unit is electrically connected with the signal output end of the alternating current amplification filtering unit and is electrically connected with the signal transmission end of the digital-to-analog conversion device through a signal processing and transmission unit, and the data signal output end of the microcontroller is transmitted to an external storage device through an I/O interface circuit for signal connection.
Further, the real-time on-line monitoring sensor device of dissolved oxygen still includes a plurality of temperature sensor, temperature sensor distributes in each sampling point department, just temperature sensor's signal output part with microcontroller's temperature information input end electricity is connected.
Further, the fluorescent film is an oxygen-sensitive ruthenium complex layer.
Further, the blue light LED is an excitation light source, the red LED is a reference light source, and the wavelength obtained by the blue light LED through the transition of a fluorescent substance is similar to the excitation wavelength of the red LED; the blue LED light source and the red LED light source are both provided with LED driving chips, and the LED driving chips are MAX1916 LED driving chips with 6 pins.
Further, the casing is the hollow pipe that 3D printed.
Further, the photoreceptor is a photodiode.
Further, the optical window is made of sapphire glass.
The control method of the dissolved oxygen real-time online monitoring sensor device is characterized by comprising the following steps of:
(1) the microcontroller controls the blue LED light source and the red LED light source to emit blue light and red light, wherein the blue light irradiates on a fluorescent substance of the sensor film, and oxygen and the fluorescence are subjected to quenching reaction to excite red fluorescence;
(2) after the excited red fluorescence penetrates through the light window, the red fluorescence passes through the red light filter to eliminate stray light interference, is captured by the photoreceptor positioned at the center of the bottom of the hollow cavity of the shell, and transmits an optical signal to the photoelectric converter;
(3) the photoelectric converter converts the acquired optical signal into a current signal, then converts the current signal into a voltage signal through the I/V converter, performs square wave modulation on the voltage signal through the alternating current amplification filtering unit, and then processes the modulated square wave signal and the square wave signal of the exciting light through the phase detection unit of the microcontroller to obtain a waveform signal representing a phase deviation value;
(4) the phase detection unit of the microcontroller transmits the waveform signal based on the voltage to the digital-to-analog conversion device, the digital-to-analog conversion device performs analog-to-digital conversion on the waveform signal based on the voltage to convert the waveform signal into a digital signal which can be processed by the microcontroller, and finally the microcontroller transmits the data to external storage equipment through an I/O interface circuit for observing and recording test results.
The use method of the dissolved oxygen real-time online monitoring sensor device is characterized by comprising the following steps of:
1) preparing fluorescent films containing different fluorescent indicators, and coating a protective layer on the surface layers of the fluorescent films for shading light and avoiding water body pollution;
2) fixing the optical window on the top of the matched shell, and then combining and fixing the fluorescent film with the protective layer with the surface of the optical window to avoid water seepage;
3) adjusting a blue LED light source and a red LED light source in the sensor device to enable the excitation wavelength to be at 450-plus 490nm and the emission wavelength to be at 580-plus 680nm, and then placing the sensor device into oxygen-free water and saturated oxygen water;
4) after the signal values measured in the oxygen-free water are stable, recording the frequency of one datum at regular time intervals and deriving a plurality of groups of signal values, namely the original phase deviation value;
5) and putting the sensor device into saturated oxygen water, deriving data for recording signal values, recording multiple groups of data again, acquiring the measured phase deviation value, and drawing a working curve of the dissolved oxygen sensor according to the acquired data.
The principle of the invention is as follows: blue light emitted from the blue LED light source irradiates the fluorescent film fluorescent substance to excite red fluorescence (oxygen and fluorescence are subjected to quenching reaction). After the fluorescence penetrates through the light window, the fluorescence passes through the red light filter to eliminate stray light interference. The photoreceptor located at the center of the shell receives fluorescence and detects the fluorescence lag phase through the analog circuit device, when the dissolved oxygen concentration is low, the fluorescence service life is prolonged, the corresponding phase lag is increased, and when the dissolved oxygen concentration is high, the fluorescence service life is reduced, and the corresponding phase lag is reduced. And the red LED light source is used as a reference of blue light emission time, the circuit is calibrated to delay, and then the dissolved oxygen concentration is obtained through calibration.
Compared with the prior art, the invention has the beneficial effect that
1. The self-made core component oxygen-sensitive fluorescent film has excellent performance, short response time, stable signal value, good reversibility and high stability;
2. the prepared optical dissolved oxygen sensor is portable and convenient to carry, and can read data in real time when being connected with a power supply, so that the convenience in working outside is greatly improved;
3. the sensor principle is a fluorescence quenching principle, the dissolved oxygen concentration can be calculated by measuring the phase difference, the fluorescence life ratio of the device is high, and the numerical value is stable and reliable;
4. the nano particle oxygen-sensitive fluorescent film containing the fluorescent indicator is prepared, and the indicator is embedded in the nano particles, so that the indicator is prevented from leaking;
5. adopt 3D printing technique to print plastic casing, carry out art processing to the sensor device.
Drawings
Fig. 1 is a schematic view of the overall structure of the present invention.
Fig. 2 is a schematic diagram of the working process of the present invention.
Detailed Description
The following detailed description of the present application, taken in conjunction with the accompanying drawings, is intended to illustrate and not limit the scope of the invention.
With reference to the accompanying drawings:
embodiment 1 the sensor device for real-time online monitoring of dissolved oxygen according to the present invention includes an optical probe 100, a photoelectric conversion unit 200, and a signal processing unit 300, where the optical probe 100 includes a housing 10, a fluorescent film 6, and a protective layer 9, a hollow cavity is disposed in the housing 10, an optical window 1 through which light can pass is disposed on the housing 10, and a side of the housing where the optical window is disposed is front, whereas the front surface of the optical window 1 is coated with the fluorescent film 6; the surface of the fluorescent film 6 is covered with a protective layer 9 for shading light and avoiding water body pollution;
the photoelectric conversion unit 200 is arranged in the hollow cavity of the housing 10, and includes a blue LED light source 2 as an excitation light source, a red LED light source 5 as a reference light source, a photoreceptor 3, a red filter 4 and an I/V converter, the blue LED light source 2 and the red LED light source 5 are respectively arranged on two opposite sides of the hollow cavity of the housing 10, and light emitting directions of the blue LED light source 2 and the red LED light source 5 are simultaneously aligned with a central area of the fluorescent film 6, so that the fluorescent film is located at the focus of the blue LED light source and the red LED light source; the photoreceptor 3 is arranged in a hollow cavity of the shell 10 right behind the fluorescent film 6, and a signal output end of the photoreceptor 3 is in circuit connection with a signal input end of the signal processing part 300 and is used for transmitting a received fluorescent signal to the signal processing part; the red light filter 4 is arranged between the fluorescent film 6 and the photoreceptor 3 and is used for eliminating the interference of stray light on the photoreceptor; the signal output end of the I/V converter is electrically connected with the signal input end of the signal processing circuit 300, and is used for converting a current signal into a voltage signal;
the signal processing circuit 300 comprises an analog circuit device 7 and a digital-to-analog conversion device 8, the analog circuit device 7 comprises an analog signal power supply and a digital power supply, the analog power supply and the digital power supply are physically isolated and respectively provided with an independent ground wire and a power supply, and the analog power supply is respectively and electrically connected with the photoreceptor, the driving end of the blue LED light source and the driving end of the red LED light source through an analog circuit and is used for controlling the sensor device to work; the digital power supply is respectively and electrically connected with the photoreceptor, the driving end of the blue LED light source, the driving end of the red LED light source and the digital-to-analog conversion device 8 through a microcontroller, and the digital power supply is in signal connection with external storage equipment through an I/O interface circuit and is used for monitoring and controlling the sensor device in real time.
The digital power supply comprises a power supply, an LED driving chip, a photoelectric converter, an I/V converter, an alternating current amplification filtering unit, a microcontroller and a signal processing and transmitting unit;
the power transmission end of the power supply is electrically connected with the LED driving chip, the photoelectric converter, the alternating current amplification filtering unit and the phase detection unit respectively;
the optical signal input end of the photoelectric converter is electrically connected with the optical signal output end of the sensor, and the current signal output end of the photoelectric converter is electrically connected with the electrical input end of the I/V converter and is used for converting an optical signal into a current signal and transmitting the current signal to the I/V converter;
the signal output end of the I/V converter is electrically connected with the signal input end of the alternating current amplification filtering unit and is used for converting a current signal into a voltage signal;
and the signal output end of the alternating current amplification filtering unit is electrically connected with the signal input end of the microcontroller and is used for carrying out square wave modulation on the voltage signal to obtain a corresponding square wave signal.
The control end of the microcontroller is electrically connected with the drive end of the blue LED light source and the red LED light source through an LED drive chip and is used for controlling the blue LED light source and the red LED light source to work; the microcontroller is internally provided with a phase detection unit, the signal input end of the phase detection unit is electrically connected with the signal output end of the alternating current amplification filtering unit and is electrically connected with the signal transmission end of the digital-to-analog conversion device through a signal processing and transmission unit, and the data signal output end of the microcontroller is transmitted to an external storage device through an I/O interface circuit for signal connection.
The dissolved oxygen real-time on-line monitoring sensor device further comprises a plurality of temperature sensors, wherein the temperature sensors are distributed at each sampling point, and the signal output end of each temperature sensor is electrically connected with the temperature information input end of the microcontroller.
The fluorescent film is an oxygen-sensitive ruthenium complex layer and contains a fluorescent indicator.
The blue LED light source and the red LED light source are both provided with LED driving chips, and the LED driving chips are MAX1916 LED driving chips with 6 pins.
The casing is the hollow pipe that 3D printed.
The photoreceptor is a photodiode.
The light window is made of sapphire glass, has a strong scratch resistance, and has the characteristics of chemical corrosion resistance, high temperature resistance, good chemical stability and high light transmittance.
Embodiment 2 the control method of the dissolved oxygen real-time on-line monitoring sensor device according to embodiment 1, comprising the steps of:
(1) the microcontroller controls the blue LED light source and the red LED light source to emit blue light and red light, wherein the blue light irradiates on a fluorescent substance of the sensor film, and oxygen and the fluorescence are subjected to quenching reaction to excite red fluorescence;
(2) after the excited red fluorescence penetrates through the light window, the red fluorescence passes through the red light filter to eliminate stray light interference, is captured by the photoreceptor positioned at the center of the bottom of the hollow cavity of the shell, and transmits an optical signal to the photoelectric converter;
(3) the photoelectric converter converts the acquired optical signal into a current signal, then converts the current signal into a voltage signal through the I/V converter, performs square wave modulation on the voltage signal through the alternating current amplification filtering unit, and then processes the modulated square wave signal and the square wave signal of the exciting light through the phase detection unit of the microcontroller to obtain a waveform signal representing a phase deviation value;
(4) the phase detection unit of the microcontroller transmits the waveform signal based on the voltage to the digital-to-analog conversion device, the digital-to-analog conversion device performs analog-to-digital conversion on the waveform signal based on the voltage to convert the waveform signal into a digital signal which can be processed by the microcontroller, and finally the microcontroller transmits the data to external storage equipment through an I/O interface circuit for observing and recording test results.
Embodiment 3 a method for using the dissolved oxygen real-time on-line monitoring sensor device as described in embodiment 1, comprising the steps of:
1) preparing fluorescent films containing different fluorescent indicators, and coating a protective layer on the surface layers of the fluorescent films for shading light and avoiding water body pollution;
2) fixing the optical window on the top of the matched shell, and then combining and fixing the fluorescent film with the protective layer with the surface of the optical window to avoid water seepage;
3) adjusting a blue LED light source and a red LED light source in the sensor device to enable the excitation wavelength to be at 450-plus 490nm and the emission wavelength to be at 580-plus 680nm, and then placing the sensor device into oxygen-free water and saturated oxygen water;
4) after the signal values measured in the oxygen-free water are stable, recording the frequency of one datum at regular time intervals and deriving a plurality of groups of signal values, namely the original phase deviation value;
5) and putting the sensor device into saturated oxygen water, deriving data for recording a signal value, recording 20 groups of data again, acquiring the measured phase deviation value, and drawing a working curve of the dissolved oxygen sensor according to the acquired data.
Specifically, a fluorescent film 6 containing a ruthenium complex indicator is fixed on a fluorescent cap, a microcontroller controls the driving work of a blue LED light source 2 and a red LED light source 5, blue exciting light emitted to the fluorescent film 6 excites fluorescent substances, emitted light (fluorescence) is received by a photoreceptor 3 of a sensor, an optical signal is converted into a current signal through a photoelectric conversion circuit, the current signal is converted into a voltage signal through an I/V converter, the voltage signal is subjected to square wave modulation, the modulated square wave signal and the square wave signal of the exciting light are subjected to calculation processing of a single chip microcomputer to obtain a phase deviation value, finally analog-to-digital conversion is carried out through a digital-to-analog conversion device, a waveform signal based on the voltage is converted into a digital signal which can be processed by the microcontroller, and finally the microcontroller transmits the data to an external storage device through an I/O interface circuit, the record is convenient to observe.
The indicator in the fluorescent film of this example was ruthenium complex I, which was replaced with ruthenium complex II, ruthenium complex III, and ruthenium complex IV after the whole experimental procedure, and the signal values and response times are shown in the following table (I)0/I100Refers to the ratio of the signal in oxygen-free water to the signal value in saturated oxygen water). The dissolved oxygen concentration measuring range of the dissolved oxygen real-time on-line monitoring sensor is 0.01-20 mg/L, the signal ratio is 3-7, the response time is less than 25s, and the sensitivity is high.
Figure BDA0003423663100000121
The embodiments described in this specification are merely illustrative of implementations of the inventive concept and the scope of the present invention should not be considered limited to the specific forms set forth in the embodiments but includes equivalent technical means as would be recognized by those skilled in the art based on the inventive concept.

Claims (10)

1. Dissolved oxygen real-time on-line monitoring sensor device, its characterized in that: the optical probe comprises a shell, a fluorescent film and a protective layer, wherein a hollow cavity is arranged in the shell, an optical window through which light can pass is arranged on the shell, the side of the shell, on which the optical window is arranged, is the front side, and otherwise, the fluorescent film is coated on the front surface of the optical window; the surface of the fluorescent film is covered with a protective layer for shading light and avoiding water body pollution;
the photoelectric conversion unit is arranged in the hollow cavity of the shell and comprises a blue LED light source serving as an excitation light source, a red LED light source serving as a reference light source, a photoreceptor, a red optical filter and an I/V converter, wherein the blue LED light source and the red LED light source are respectively arranged on two opposite sides of the hollow cavity of the shell, and the light emitting directions of the blue LED light source and the red LED light source are simultaneously aligned to the central area of the fluorescent film, so that the fluorescent film is positioned at the focuses of the blue LED light source and the red LED light source; the photoreceptor is arranged in a hollow cavity of the shell right behind the fluorescent film, and a fluorescent signal output end of the photoreceptor is connected with a fluorescent signal input end circuit of the signal processing part and used for transmitting a received fluorescent signal to the signal processing part; the red light filter is arranged between the fluorescent film and the photoreceptor and is used for eliminating the interference of stray light on the photoreceptor; the signal output end of the I/V converter is electrically connected with the signal input end of the signal processing circuit and is used for converting a current signal into a voltage signal;
the signal processing circuit comprises an analog circuit device and a digital-to-analog conversion device, the analog circuit device comprises an analog power supply and a digital power supply, the analog power supply and the digital power supply are physically isolated and respectively provided with an independent ground wire and a power supply, and the analog power supply is respectively and electrically connected with the light sensor, the driving end of the blue LED light source and the driving end of the red LED light source through the analog circuit and is used for controlling the sensor equipment to work; the digital power supply is respectively and electrically connected with the photoreceptor, the driving end of the blue LED light source, the driving end of the red LED light source and the digital-analog conversion device through a microcontroller, and the digital power supply is in signal connection with external storage equipment through an I/O interface circuit and is used for monitoring and controlling the sensor device in real time.
2. The real-time on-line dissolved oxygen monitoring sensor device according to claim 1, wherein: the digital power supply comprises a power supply, an LED driving chip, a photoelectric converter, an I/V converter, an alternating current amplification filtering unit, a microcontroller and a signal processing and transmitting unit;
the power transmission end of the power supply is electrically connected with the LED driving chip, the photoelectric converter, the alternating current amplification filtering unit and the phase detection unit respectively;
the optical signal input end of the photoelectric converter is electrically connected with the optical signal output end of the sensor, and the current signal output end of the photoelectric converter is electrically connected with the electrical input end of the I/V converter and is used for converting an optical signal into a current signal and transmitting the current signal to the I/V converter;
the signal output end of the I/V converter is electrically connected with the signal input end of the alternating current amplification filtering unit and is used for converting a current signal into a voltage signal;
and the signal output end of the alternating current amplification filtering unit is electrically connected with the signal input end of the microcontroller and is used for carrying out square wave modulation on the voltage signal to obtain a corresponding square wave signal.
The control end of the microcontroller is electrically connected with the drive end of the blue LED light source and the red LED light source through an LED drive chip and is used for controlling the blue LED light source and the red LED light source to work; the microcontroller is internally provided with a phase detection unit, the signal input end of the phase detection unit is electrically connected with the signal output end of the alternating current amplification filtering unit and is electrically connected with the signal transmission end of the digital-to-analog conversion device through a signal processing and transmission unit, and the data signal output end of the microcontroller is transmitted to an external storage device through an I/O interface circuit for signal connection.
3. The real-time on-line dissolved oxygen monitoring sensor device according to claim 2, wherein: the dissolved oxygen real-time on-line monitoring sensor device further comprises a plurality of temperature sensors, wherein the temperature sensors are distributed at each sampling point, and the signal output end of each temperature sensor is electrically connected with the temperature information input end of the microcontroller.
4. The real-time on-line dissolved oxygen monitoring sensor device according to claim 3, wherein: the fluorescent film is an oxygen-sensitive ruthenium complex layer.
5. The real-time on-line dissolved oxygen monitoring sensor device according to claim 4, wherein: the blue LED light source and the red LED light source are both provided with LED driving chips, and the LED driving chips are MAX1916 LED driving chips with 6 pins.
6. The real-time on-line dissolved oxygen monitoring sensor device according to claim 4, wherein: the casing is the hollow pipe that 3D printed.
7. The real-time on-line dissolved oxygen monitoring sensor device according to claim 1, wherein: the photoreceptor is a photodiode.
8. The real-time on-line dissolved oxygen monitoring sensor device according to any one of claims 1 to 7, wherein: the light window is made of sapphire glass.
9. The control method of the dissolved oxygen real-time on-line monitoring sensor device according to any one of claim 8, comprising the steps of:
(1) the microcontroller controls the blue LED light source and the red LED light source to emit blue light and red light, wherein the blue light irradiates on a fluorescent substance of the sensor film, and oxygen and the fluorescence are subjected to quenching reaction to excite red fluorescence;
(2) after the excited red fluorescence penetrates through the light window, the red fluorescence passes through the red light filter to eliminate stray light interference, is captured by the photoreceptor positioned at the center of the bottom of the hollow cavity of the shell, and transmits an optical signal to the photoelectric converter;
(3) the photoelectric converter converts the acquired optical signal into a current signal, then converts the current signal into a voltage signal through the I/V converter, performs square wave modulation on the voltage signal through the alternating current amplification filtering unit, and then processes the modulated square wave signal and the square wave signal of the exciting light through the phase detection unit of the microcontroller to obtain a waveform signal representing a phase deviation value;
(4) the phase detection unit of the microcontroller transmits the waveform signal based on the voltage to the digital-to-analog conversion device, the digital-to-analog conversion device performs analog-to-digital conversion on the waveform signal based on the voltage to convert the waveform signal into a digital signal which can be processed by the microcontroller, and finally the microcontroller transmits the data to external storage equipment through an I/O interface circuit for observing and recording test results.
10. The use method of the dissolved oxygen real-time on-line monitoring sensor device according to any one of claim 8, characterized by comprising the following steps:
1) preparing fluorescent films containing different fluorescent indicators, and coating a protective layer on the surface layers of the fluorescent films for shading light and avoiding water body pollution;
2) fixing the optical window on the top of the matched shell, and then combining and fixing the fluorescent film with the protective layer with the surface of the optical window to avoid water seepage;
3) adjusting a blue LED light source and a red LED light source in the sensor device to enable the excitation wavelength to be at 450-plus 490nm and the emission wavelength to be at 580-plus 680nm, and then placing the sensor device into oxygen-free water and saturated oxygen water;
4) after the signal values measured in the oxygen-free water are stable, recording the frequency of one datum at regular time intervals and deriving a plurality of groups of signal values, namely the original phase deviation value;
5) and putting the sensor device into saturated oxygen water, deriving data for recording signal values, recording multiple groups of data again, acquiring the measured phase deviation value, and drawing a working curve of the dissolved oxygen sensor according to the acquired data.
CN202111570827.2A 2021-12-21 2021-12-21 Dissolved oxygen real-time online monitoring sensor device, control method and use method Pending CN114264637A (en)

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