CN111398239B

CN111398239B - Dissolved oxygen measuring device based on fluorescence quenching method

Info

Publication number: CN111398239B
Application number: CN202010424454.7A
Authority: CN
Inventors: 王相; 庞喜龙; 田聪聪; 王钟轩; 于家浩
Original assignee: Weihai Jingxun Changtong Electronic Technology Co Ltd
Current assignee: Weihai Jingxun Changtong Electronic Technology Co Ltd
Priority date: 2020-05-19
Filing date: 2020-05-19
Publication date: 2022-11-25
Anticipated expiration: 2040-05-19
Also published as: CN111398239A

Abstract

The invention discloses a dissolved oxygen measuring device based on a fluorescence quenching method, which relates to the field of measuring equipment, and adopts the technical scheme that the shell structure and the internal light path structure of a detection device are improved; improvements are made to the detection circuit; the preparation method of the membrane is improved. The invention has the beneficial effects that: the shell structure of the dissolved oxygen measuring device is improved, and through the improvement of each fixing component and the light path part, the accuracy is higher than that of the existing scheme under the condition of small volume. Through the improvement to the detection circuit, the interference that receives when reducing the detection, further assurance testing result is accurate. By improving the preparation method of the fluorescent membrane, the service life and the sensitivity of the membrane are improved.

Description

Dissolved oxygen measuring device based on fluorescence quenching method

Technical Field

The invention relates to the field of measuring equipment, in particular to a dissolved oxygen measuring device based on a fluorescence quenching method.

Background

The amount of dissolved oxygen in water is an index for measuring the self-purification capacity of water. Temperature, dissolved oxygen, pH, conductivity, turbidity, chemical oxygen demand, total organic carbon and the like are several important indexes for evaluating the quality of the water body. Can realize the real-time supervision to aquatic dissolved oxygen through dissolved oxygen check out test set, other monitoring parameters such as PH value, turbidity can obtain the quality of water situation fast more than combining, and then in time carry out relevant renovation work. Furthermore, the measurement of dissolved oxygen has important applications in brewing processes, papermaking processes, metallurgical processes and biomedicine. Therefore, the measurement of the concentration of the dissolved oxygen has important significance for environmental protection, aquaculture, industrial production and scientific research experiments.

The measurement methods of the dissolved oxygen in water are various, and at present, an iodometric method, an electrochemical method, a spectrophotometric method and a fluorescence method are more commonly used. The iodometry method is also called Winkler method, is an internationally recognized reference method for measuring dissolved oxygen in water, and is one of national standards in China. Not only needs to consume a certain amount of dissolved oxygen of a sample, but also has complicated procedures and long time consumption, and can not meet the requirement of on-line measurement. The sensor manufactured by the electrochemical method has the defects of easy pollution, frequent replacement and cleaning, instability, easy failure and the like.

In contrast, the fluorescence quenching method has the advantages of good photochemical stability, reproducibility, no delay, high precision, long service life and the like, and can further detect the dissolved oxygen in water in real time. Therefore, the improvement of the requirement of water quality detection makes people favor of using a fluorescence quenching method to detect the content of dissolved oxygen.

In the twenty-fourth century, after the fluorescence quenching method was proposed to measure the dissolved oxygen concentration in water in the H.Kausky's, many scientists began to continuously study the fluorescence quenching method to measure the dissolved oxygen concentration, and have been slowly commercially available, and in the field of the current foreign dissolved oxygen measurement, the fluorescence quenching method was mainly used to measure the dissolved oxygen concentration in water, and the research and production technology has been well developed, and representative examples of some of the manufacturers of dissolved oxygen meters using fluorescence quenching include

WTW in Germany, AANDERAA in Norway, HACH in USA, PONSEL in France, etc. However, these imported dissolved oxygen meters are expensive, have long ordering periods and are cumbersome to maintain, and are not suitable for mass popularization. Therefore, the fluorescence quenching dissolved oxygen detection sensor which is independently developed, designed and produced by completely independent intellectual property rights is urgently needed in China to make up for the defects in the field of fluorescence quenching dissolved oxygen measurement and shorten the gap with the international first-class level.

Disclosure of Invention

In order to solve the technical problems, the invention provides a dissolved oxygen measuring device based on a fluorescence quenching method.

The technical scheme is that the device comprises a shell, wherein one end of the shell is a detection end, the other end of the shell is a tail end, and a waterproof sheath joint is arranged at the tail end; the detection end is provided with a fluorescent diaphragm, and an excitation light source and a reference light source which correspond to the fluorescent diaphragm; the detection circuit is also included; it is characterized in that the preparation method is characterized in that,

the detection end of the shell is fixedly connected with the diaphragm mounting part; a fixing piece for mounting an electrical element is arranged in the detection end;

the fixing piece is a block corresponding to the inner cavity of the shell, a receiving hole is formed in the middle of the fixing block, emitting holes are symmetrically formed in two sides of the receiving hole, and a sensor receiving end used for receiving fluorescence of the fluorescent film is arranged on one side, far away from the film mounting portion, of the receiving hole; two red light source and blue light source are placed respectively to the inside red light source and the blue light source of placing of emission hole orientation the one end of diaphragm installation department is the horn mouth, and red light source and blue light source are 610nm red light source's reference light source respectively, and 470nm blue light source excitation light source.

Preferably, a circuit board mounting table for mounting a circuit board is arranged on one side of the fixing member away from the diaphragm mounting portion.

Preferably, the axis extension line of the transmitting hole is intersected with the axis extension line of the receiving hole, the transmitting hole comprises an installation part for installing a light source component and a light path part communicated with the installation part, the installation part and the light path part are cylindrical passages, the light path part and the installation part are coaxial, the inner diameter of the light path part is smaller than that of the installation part, a transition part is arranged between the light path part and the installation part, the transition part is a frustum-shaped through hole, and two ends of the transition part are respectively connected with the installation part and the light path part;

the horn mouth is arranged at the outer end of the light path end of the emission hole where the blue light source is located. In the shell structure scheme that this application reduces as far as possible, the transmission hole upper portion of two light sources is unanimous to guaranteed the components and parts as the light source, like the simple to operate of diode, in order to guarantee device overall structure's steadiness, consequently adopt the light path portion that sets up less aperture in the outside light path that extends of installation department, such structure can let light path portion with sufficient wall thickness has between the accepting hole, thereby guarantee that inner structure is firm. The horn mouth is arranged at the outer side end of the light path part, the light path part of the blue light source is not directly and integrally enlarged, the wall thickness between the receiving hole and the light path part is enough and safe, and the volume of the device cannot be increased.

Preferably, the diaphragm installation department is the cylinder, link up the diaphragm installation department along diaphragm installation department axial direction and set up the cavity, and the inside cavity of diaphragm installation department is fluorescence reaction chamber, through fluorescence diaphragm, reference light source, excitation light source, combines the sensor receiving end to realize the measurement to dissolved oxygen, and the diaphragm installation department is kept away from the fixed diaphragm support that is provided with of one end of shell, the diaphragm support is including setting up annular boss on the diaphragm installation department cavity perisporium, the circular open-ended diameter in annular boss middle part is less than the external diameter of fluorescence diaphragm, and annular boss is kept away from one side of shell tail end is fixed and is set up a plurality of cubic boss, and cubic boss circumference array is provided with a plurality of, and the middle part reserved space of cubic boss array corresponds with the fluorescence diaphragm, and the space diameter that should reserve with the external diameter of fluorescence diaphragm equals.

Preferably, a connecting piece is arranged in the diaphragm mounting part, and the diaphragm mounting part is fixedly connected with the fixing piece through the connecting piece;

the connecting piece is an annular plate body fixedly arranged on the inner wall of the cavity of the diaphragm mounting part, and the connecting piece is arranged at one end, close to the fixing piece, in the diaphragm mounting part;

a plurality of through holes are uniformly distributed in a circumferential array on the plate body of the connecting piece, and the number of the through holes is even;

the fixing piece is provided with a mounting hole corresponding to the through hole on the connecting piece, the through hole on the connecting piece not only plays a role in correspondingly connecting the screw hole and the mounting hole, but also plays a role in heat dissipation by redundant through holes;

the diameter of the opening in the middle of the connecting piece is smaller than or equal to the length of a connecting line between the receiving hole and the outer side end of the transmitting hole.

Preferably, the diaphragm mounting part is a cylinder, and a plurality of notches are formed in the circumferential array of the end part of the diaphragm mounting part;

a film head mounting device is arranged corresponding to the notch, and the film head mounting device is a hollow cylindrical block;

the membrane head mounting device is characterized in that a partition plate is arranged in the membrane head mounting device, an inner cavity of the membrane head mounting device comprises a locking portion and a storage portion, the inner diameter of the locking portion is equal to the outer diameter of the membrane mounting portion, and a plurality of limiting blocks corresponding to the notches are arranged on one side, facing the locking portion, of the partition plate.

Preferably, the circumference of the outer wall of the membrane head mounting device is provided with a plurality of ribs, and the ribs are arranged along the radial direction of the membrane head mounting device.

Through this structure, because the outside smooth cylinder that is exactly of membrane head installation department, when needs change diaphragm or membrane head installation department, need take off membrane head installation department, the sense terminal threaded connection of membrane head installation department and shell, it is not good enough to twist the effect bare-handed soon, consequently, through the membrane head erector as mounting tool when installation and dismantlement, when needs are installed or are dismantled the membrane head installation department, place the membrane head installation department with the locking in, the stopper card is gone into to the notch, through twisting the installation that the membrane head erector can be convenient or dismantle the membrane head installation department.

Preferably, the tail end of the shell is of a stepped structure, and the stepped structure part of the tail end of the shell is provided with external threads respectively.

Preferably, the inner diameter of the storage part is slightly larger than the outer diameter of the diaphragm mounting part, and a sealing plug is arranged at the end part of the storage part.

Preferably, the waterproof sheath joint is a cone made of elastic material, and a spare membrane head mounting part can be additionally arranged in the end with larger area of the waterproof sheath joint and the storage part of the shell.

The tail ends are connected by screw threads, the peripheral wall of the waterproof sheath joint is provided with a plurality of annular grooves which are arranged along the axial direction of the waterproof sheath joint,

the middle part of the partition board is provided with a through hole, and the through hole of the partition board is equal to the outer diameter of the annular groove of the waterproof sheath joint positioned at the lowest part of the waterproof sheath joint. The outer diameter of the position can be the outer diameter of any edge of the groove of the position, and the waterproof sheath joint is an elastic body, so that no matter which radius the waterproof sheath joint is clamped at the position, the waterproof sheath joint is not influenced. Through the structure, when the membrane head installer is not used, the membrane head installer can be inserted on the waterproof protective sleeve joint, so that the membrane head installer is prevented from being lost.

Preferably, the outer edge of the membrane mounting part is slightly higher than the outer side surface of the fluorescent membrane. When the fluorescent film is placed in the film support, the edge of the film mounting part is higher than the outer side surface of the fluorescent film by more than 1 mm.

Preferably, the detection circuit comprises a light source excitation circuit used as a detection light source, and the light source excitation circuit comprises an excitation light source excitation circuit and a reference light source excitation circuit which are respectively electrically connected with the main controller and form a control loop;

the detection circuit further comprises an acquisition channel, wherein the acquisition channel comprises an IV conversion circuit, an isolated direct current circuit, a reference voltage circuit, an amplifying circuit and an ADC acquisition circuit which are sequentially connected; the ADC acquisition circuit is electrically connected with the input end of the main controller, the IV conversion circuit is electrically connected with a receiving diode, and the receiving diode receives an optical signal fed back by the fluorescent sensitive touch;

and a power supply path electrically connected with each component.

Preferably, the dc blocking circuit and the reference voltage circuit are connected in series in a unidirectional input path of the amplifier a in the amplifying circuit;

the isolation direct current circuit is a capacitor C5 arranged on a homodromous input path of the amplifier A;

the reference voltage circuit comprises a pull-up resistor R12 and a pull-down resistor R16 which are arranged on the same-direction input path of the amplifier A.

Preferably, the type of the amplifier a in the amplifying circuit is TP1252.

Preferably, the IV conversion circuit includes an amplifier B connected to the receiving diode, a non-inverting input terminal and an inverting input terminal of the amplifier B are connected across both ends of the receiving diode, the inverting input terminal of the amplifier B is connected to a cathode of the receiving diode, and the non-inverting input terminal of the amplifier B is connected to an anode of the receiving diode.

Preferably, the communication circuit is a 485 communication circuit.

Preferably, the main controller adopts an MCU processor, and the model is STM32.

Preferably, the input end of the main controller is further connected with a temperature compensation circuit, and the output end of the main controller is connected with a communication circuit.

Preferably, the fluorescent membrane comprises a carrier layer, an adhesive layer, a fluorescent layer and a fluorescent protection layer which are arranged in sequence. In use, the carrier layer is adjacent to the excitation light source and the reference light source.

Preferably, the preparation method of the fluorescent membrane comprises the following steps:

s1, selecting quartz glass or polyester sheets with light transmittance of more than or equal to 95% as a substrate, namely the carrier layer, the diameter of which is 14.5mm and the thickness of which is 2mm, and soaking the substrate in 1mol/L NaOH for 24H before use to remove acidity;

s2, backwashing the substrate treated in the S1 for 2 times by using absolute ethyl alcohol and 3 times by using deionized water to remove surface impurities, and drying the substrate in an oven at 50 ℃ for later use;

s3, dissolving polyvinyl chloride Powder (PVC) in Tetrahydrofuran (THF), and adding di (2-ethylhexyl) phthalate (DEHP) as a glue layer material; the proportion is as follows: (PVC): (DEHP): (THF) = 10g:20g:100ml.

S4, after being inhaled, ingested or absorbed through skin, di (2-ethylhexyl) phthalate (DEHP), the di (2-ethylhexyl) phthalate is harmful to the body and has a stimulating effect on the skin, and vapor or smoke of the di (2-ethylhexyl) phthalate has a stimulating effect on eyes, mucous membranes and upper respiratory tracts. Contact can lead to gastrointestinal dysfunction. Uniformly coating the glue layer material prepared in the step S3 on the substrate treated in the step S2 by using a spin coater;

because the surface of the carrier layer is smooth and has poor adhesive force, the adhesive layer can be completely adsorbed on the glass slide of the carrier layer, so that the surface adhesive force is improved, and the adhesive layer is not easy to dissolve in water.

The spin coating method of S4 comprises the following steps: 60ul of glue layer solution is dripped in the middle of the carrier slide, 400R/M,5S;1500R/M,20S; taking out the materials in parallel after the 400R/M and 5S spin coating, and drying for 5 minutes at 50 ℃ in a dust-free environment.

S5, preparing a fluorescent indicator, wherein tris (4,7-biphenyl-1,10-phenanthroline) ruthenium dichloride (Ru (dpp) 3Cl 2) is selected as a main material, and the fluorescent indicator is characterized by being basically insoluble in water, long in fluorescence lifetime and high in sensitivity;

adding 250mg of tris (4,7-biphenyl-1,10-phenanthroline) ruthenium dichloride (Ru (dpp) 3Cl 2) into 100ml of absolute ethanol, and uniformly mixing by ultrasonic waves to prepare a fluorescent indicator solution;

using liquid to rush 2ml of Tetraethoxysilane (TEOS) and 1ml of trifluoropropyltrimethoxysilane (TEP-TriMOS) or dimethyldiethoxysilane (DDS) to be added into a 10ml round-bottom flask, then continuously adding 0.234ml of deionized water and 1.25ml of absolute ethyl alcohol, adding a catalyst of hydrochloric acid to adjust the PH to 1.2, covering and sealing the flask, magnetically stirring the flask for 1 hour, adding 0.5ml of a fluorescent indicator of ethanol solution by using a liquid gun, ultrasonically stirring the mixture for 10 minutes, then putting the mixture into a dark environment to age for 48 hours, and aging 60ul of sol for 5s, 3000r/min and 30s at the speed of 500 r/min; uniformly spin-coating the substrate obtained in step S4 at a speed of 500r/min for 5S; preparing a slide with a fluorescent indicator, and aging for more than 7 days in a dark place;

the precursor is a simple TEOS gel film, the TEOS gel film has large net-shaped holes and uneven pore size distribution, the indicator can be wrapped in the holes, the large net-shaped holes easily cause leakage of the embedded indicator, the pore size distribution is uneven, so that the gel is easy to generate uneven internal stress when being dried, and the film is cracked.

When a certain amount of dimethyl diethoxy silane DDS (the volume of DDS/TEOS is 1:2) is added into the precursor, the pore size in the gel film is reduced, and the pore size distribution tends to be uniform. Because a large number of ((CH 3) 2 SI-O-) n cyclic molecules are formed in the DDS hydrolysis process, the cyclic molecules have modification effects of filling gaps, reducing pore size and capillary stress, reducing gel shrinkage and the like. Thereby making the gel film less prone to cracking and having good flexibility, while the embedded indicator is more uniform and less prone to leakage.

S6, preparing a fluorescent protection layer, wherein the fluorescent protection layer protects the influence of external light on the fluorescent layer, reduces the damage of external flowing water on the fluorescent layer, can also penetrate oxygen molecules in water, is slightly soluble in water or insoluble in water, and is corrosion-resistant;

1g of carbon black with the diameter of 50nm needs to be selected and used for keeping out of the sun, 1g of one of 50nm metal powder such as noble metal Jin Yinbo and the like is needed, the surface strength is increased, and the damage of acid and alkali is better resisted.

Dissolving the carbon black and the metal powder by using 200ml of toluene solution and 1ml of naphthol, and magnetically stirring for 1 hour; 30ul of sol is mixed for 5s at 200 r/min; 1000r/min,30s; and (5) uniformly spin-coating the substrate treated with the S5 for 5 seconds at 200r/min, and drying in an oven at 50 ℃.

The technical scheme provided by the embodiment of the invention has the following beneficial effects: the shell structure of this scheme of adoption, small, it is with low costs. Through the structure of this scheme mounting, can further improve the measurement accuracy of sensor. Through the membrane head structure of this scheme, there is better fixed effect to the fluorescence diaphragm, and cooperates specific membrane head erector, dismouting diaphragm installation department that can be convenient. The shell structure that this scheme of adoption provided lets dissolved oxygen sensor possess higher level.

The dissolved oxygen measuring circuit has the advantages of low cost, small volume, good portability, no need of complex operation, capability of measuring the dissolved oxygen in water on line in real time, and scientific research and commercial value.

Drawings

Fig. 1 is a schematic overall structure diagram of an embodiment of the present invention.

Fig. 2 is an exploded view of a hidden housing according to an embodiment of the present invention.

Fig. 3 is a partially enlarged view a of fig. 2.

Fig. 4 is a schematic view of a fixing member according to an embodiment of the present invention.

Fig. 5 is a front view of a fastener in accordance with an embodiment of the present invention.

Fig. 6 isbase:Sub>A sectional view taken along linebase:Sub>A-base:Sub>A of fig. 5.

Fig. 7 is a circuit diagram of a power isolation circuit according to an embodiment of the invention.

FIG. 8 is a perspective view of the back of the diaphragm mounting portion according to the embodiment of the present invention.

Fig. 9 is a functional block diagram of an embodiment of the present invention.

FIG. 10 is a circuit diagram of a reference light source according to an embodiment of the invention.

FIG. 11 is a circuit diagram of an excitation light source according to an embodiment of the invention.

FIG. 12 is a circuit diagram of a temperature measurement circuit according to an embodiment of the present invention.

Fig. 13 is a diagram of an IV conversion circuit according to an embodiment of the present invention.

Fig. 14 is a circuit diagram of a dc isolation circuit, a reference voltage circuit, and an amplifying circuit according to an embodiment of the invention.

Wherein the reference numerals are: 1. a housing; 2. a diaphragm mounting portion; 201. a support; 202. an annular boss; 203. a block-shaped boss; 204. a connecting member; 205. a recess; 3. a waterproof jacket joint; 4. a fluorescent membrane; 5. a fixing member; 51. a receiving aperture; 52. an emission aperture; 521. an installation part; 522. a light path section; 523. a transition portion; 53. mounting holes; 54. a circuit board mounting table; 55. a bell mouth; 6. a membrane head installer; 61. a partition plate; 62. a locking portion; 63. and a limiting block.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. Of course, the specific embodiments described herein are merely illustrative of the invention and are not intended to be limiting.

It should be noted that the embodiments and features of the embodiments of the present invention may be combined with each other without conflict.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientation or positional relationship indicated in the drawings, which are merely for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be construed as limiting the invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate a number of the indicated technical features. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature. In the description of the invention, "a plurality" means two or more unless otherwise specified.

In the description of the invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted", "connected" and "disposed" are to be construed broadly, e.g. as being fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the creation of the present invention can be understood by those of ordinary skill in the art through specific situations.

Example 1

Referring to fig. 1 to 8, the invention provides a dissolved oxygen measuring device based on a fluorescence quenching method, which comprises a shell 1, wherein one end of the shell 1 is a detection end, the other end of the shell is a tail end, and a waterproof sheath joint 3 is arranged at the tail end; the detection end is provided with a fluorescent diaphragm, and an excitation light source and a reference light source which correspond to the fluorescent diaphragm; the detection circuit is also included; it is characterized in that the preparation method is characterized in that,

the detection end of the shell 1 is fixedly connected with the diaphragm mounting part 2; a fixing piece 5 for mounting an electric element is arranged in the detection end;

the fixing piece 5 is a block corresponding to the inner cavity of the shell 1, a receiving hole 51 is formed in the middle of the fixing piece 5, emitting holes 52 are symmetrically formed in two sides of the receiving hole 51, and a sensor receiving end used for receiving fluorescence of the fluorescent film is arranged on one side, away from the film mounting part 2, of the receiving hole 51; red light source and blue light source are placed respectively to inside two emission holes 52, and the one end of placing blue light source's emission hole 52 towards diaphragm installation department 2 is horn mouth 55, and red light source and blue light source are 610nm red light source's reference light source respectively, and 470nm blue light source excitation light source let more blue light can follow emission hole 52 and jet out through setting up horn mouth 55 to make the blue light facula and the red light facula on the final fluorescence diaphragm 4 equal. The diameter of the light outlet of the red light on one side of the fixing part 5 facing the fluorescent membrane 4 is 2mm, and the diameter of the blue light outlet, namely the large-opening end of the bell mouth 55, is 3mm.

In the existing dissolved oxygen sensors based on the fluorescence quenching method, red and blue lights are respectively used as an excitation light source and a reference light source, and the red and blue lights are projected onto a fluorescent diaphragm, so that the sensor is used for acquiring an optical signal of the fluorescent diaphragm, and the dissolved oxygen is measured. Through research, in practical use, the two lights of red and blue have different optical characteristics, so that the two lights have different effects of being projected on the fluorescent film, and the difference directly influences the accuracy of the measurement result of the final sensor.

Researches show that the projection difference caused by the red light and the blue light is that the size of light spots projected on the fluorescent film is not used, and the diameter of the light spots projected by the blue light is smaller than that of the red light, so that the accuracy of the measurement result of the sensor is influenced. For the reason that the light spot of the blue light projected to the fluorescent film is small, the analysis shows that the included angles and the distances between the two light sources and the central line of the fluorescent film are equal in structure, so that the influence factors of the arrangement positions of the two light sources can be eliminated. The characteristic problem of red and blue light is considered, the wavelength of the red light is longer, the red light is more stable, and the penetrating power is strong; the blue light wavelength is shorter, the diffraction capability is far lower than that of the red light, the penetrating power is weak, and under the combined condition of the structural bodies, because the light sources of the blue light and the red light are positioned at the mirror image positions, the diameter of a light spot irradiated by the blue light on the fluorescent film is smaller than that of the red light, and the light spot is used as a sensor component with higher precision requirement, and the difference causes the problem that the accuracy of the final detection result is reduced. Therefore, under the condition of the problems, the light-emitting rate of the blue light source is increased through the horn mouth, and the defect of the prior art is overcome.

The side of the fixing member 5 remote from the diaphragm mounting portion 2 is provided with a circuit board mounting table 54 for mounting a circuit board.

The axial extension line of the emitting hole 52 is intersected with the axial extension line of the receiving hole, the emitting hole 52 comprises an installation part 521 for installing a light source component and an optical path part 522 communicated with the installation part 521, the installation part 521 and the optical path part 522 are both cylindrical passages, the optical path part 522 is coaxial with the installation part 521, the inner diameter of the optical path part 522 is smaller than that of the installation part 521, a transition part 523 is arranged between the optical path part 522 and the installation part 521, the transition part 523 is a frustum-shaped through hole, and two ends of the transition part 523 are respectively connected with the installation part 521 and the optical path part 522;

the outer end of the light path portion 522 of the emission hole 52 in which the blue light source is located is opened with a bell mouth 55. In the shell structure scheme that this application reduces as far as possible, the transmission hole 52 upper portion of two light sources is unanimous to guaranteed the components and parts as the light source, like the simple to operate of diode, in order to guarantee the steadiness of device overall structure, consequently adopted and set up the light path portion 522 in less aperture on the light path that installation department 521 outwards extended, such structure can let have sufficient wall thickness between light path portion 522 and receiving hole 51, thereby guarantees that inner structure is firm. However, the bell mouth 55 is provided at the outer end of the optical path 522, and it is considered that the thickness between the receiving hole 51 and the optical path 522 is sufficiently large and the volume of the device is not increased, rather than directly enlarging the optical path of the blue light source as a whole.

Diaphragm installation department 2 is the cylinder, 2 axial directions link up diaphragm installation department 2 along the diaphragm installation department and offer the cavity, 2 inside cavities of diaphragm installation department are fluorescence reaction chamber, through fluorescence diaphragm 4, reference light source, excitation light source, combine the sensor receiving terminal to realize the measurement to dissolved oxygen, 2 one end that keep away from shell 1 of diaphragm installation department is fixed and is provided with diaphragm support 201, diaphragm support 201 is including setting up the annular boss 202 on 2 cavity perisporium of diaphragm installation department, the circular open-ended diameter in annular boss 202 middle part is less than the external diameter of fluorescence diaphragm, one side that 1 tail end of shell was kept away from to annular boss 202 is fixed and is set up a plurality of cubic boss 203, cubic boss 203 circumference array is provided with a plurality of, the middle part reserved space of cubic boss 203 array corresponds with the fluorescence diaphragm, and the space diameter that should reserve equals with the external diameter of fluorescence diaphragm.

A connecting piece 204 is arranged in the diaphragm mounting part 2, and the diaphragm mounting part 2 is fixedly connected with the fixing piece 5 through the connecting piece 204;

the connecting piece 204 is an annular plate fixedly arranged on the inner wall of the cavity of the diaphragm mounting part 2, and the connecting piece 204 is arranged at one end, close to the fixing piece 5, in the diaphragm mounting part 2;

a plurality of through holes are uniformly distributed in a circumferential array on the plate body of the connecting piece 204, and the number of the through holes is even;

the fixing piece 5 is provided with a mounting hole 53 corresponding to the through hole on the connecting piece 204, the through hole on the connecting piece 204 not only has the function of corresponding connection between the screw hole and the mounting hole 53, but also has the function of heat dissipation through redundant through holes;

the diameter of the opening in the middle of the connecting piece 204 is less than or equal to the length of the connecting line between the receiving hole 51 and the outer side end of the transmitting hole 52.

Example 2

On the basis of the embodiment 1, the membrane mounting part 2 is a cylinder, and a plurality of notches 205 are formed in the circumferential array at the end part of the membrane mounting part 2;

a film head mounting device 6 is arranged corresponding to the notch 205, and the film head mounting device 6 is a hollow cylindrical block;

the membrane head mounting device 6 is internally provided with a partition 61, the partition 61 enables the cavity inside the membrane head mounting device 6 to comprise a locking part 62 and a storage part, the inner diameter of the locking part 62 is equal to the outer diameter of the membrane mounting part 2, and one side of the partition 61 facing the locking part 62 is provided with a plurality of limiting blocks 63 corresponding to the notches 205.

The outer wall circumference of the film head mounting device 6 is provided with a plurality of ribs which are arranged along the radial direction of the film head mounting device 6.

Through this structure, because the outside of membrane head installation department 2 is exactly smooth cylinder, when needs change diaphragm or membrane head installation department 2, need take off membrane head installation department 2, the detection end threaded connection of membrane head installation department 2 and shell 1, it is not good enough to twist the effect bare-handed soon, therefore, through membrane head erector 6 as mounting tool when installation and dismantlement, when needs are installed or are dismantled membrane head installation department 2, place membrane head installation department 2 with locking portion 62 in, stopper 63 card is gone into to notch 205, through twisting the installation that membrane head erector 6 can be convenient or dismantle membrane head installation department 2.

The tail end of the shell 1 is of a step-type structure, and the step-type structure part of the tail end of the shell 1 is provided with external threads respectively.

The inner diameter of the storage part is slightly larger than the outer diameter of the diaphragm mounting part 2, and the end part of the storage part is provided with a sealing plug.

An additional spare film head mounting part 2 can be placed in the storage part.

Example 3

On the basis of the embodiment 2, the waterproof sheath connector 3 is a cone made of elastic material, one end of the waterproof sheath connector 3 with larger area is in threaded connection with the tail end of the shell 1, the peripheral wall of the waterproof sheath connector 3 is provided with a plurality of annular grooves which are arranged along the axial direction of the waterproof sheath connector 3,

the middle part of the partition board 61 is provided with a through hole, and the through hole of the partition board 61 is equal to the outer diameter of the annular groove of the waterproof sheath joint 3 positioned at the lowest part of the waterproof sheath joint 3. The outer diameter of the place can be the outer diameter of any edge of the groove of the place, and because the waterproof sheath connector 3 is an elastic body, no matter which radius the upper and lower parts of the groove of the place are, the waterproof sheath connector 3 is not influenced to be clamped at the place. With such a structure, when the membrane head mounting device 6 is not used, the membrane head mounting device 6 can be inserted into the waterproof sheath joint 3 to avoid loss.

Example 4

On the basis of any of the above embodiments, the outer edge of the membrane mounting part 2 is slightly higher than the outer side surface of the fluorescent membrane 4. When the fluorescent film 4 is placed in the film holder 201, the edge of the film mounting portion 2 is higher than the outer side surface of the fluorescent film 4 by 1mm or more.

Example 5

Referring to fig. 9 to 14, the detection circuit of the present embodiment includes a light source excitation circuit for serving as a detection light source, and the light source excitation circuit includes an excitation light source excitation circuit and a reference light source excitation circuit that are electrically connected to the main controller and form a control loop, respectively;

the reference light source is a red light source with the wavelength of 610nm, and the excitation light source is a blue light source with the wavelength of 470 nm.

The acquisition channel comprises an IV conversion circuit, an isolated direct current circuit, a reference voltage circuit, an amplifying circuit and an ADC acquisition circuit which are connected in sequence; the ADC acquisition circuit is electrically connected with the input end of the main controller, the IV conversion circuit is electrically connected with the receiving diode, and the receiving diode receives an optical signal fed back by the fluorescent sensitive touch;

the input end of the main controller is also connected with a temperature compensation circuit, and the output end of the main controller is connected with a communication circuit;

and a power supply path electrically connected with each component.

The isolation direct current circuit and the reference voltage circuit are connected in series in a same-direction input channel of an amplifier A in the amplifying circuit;

the isolation direct current circuit is a capacitor C5 arranged on the equidirectional input path of the amplifier A;

the reference voltage circuit includes a pull-up resistor R12 and a pull-down resistor R16 provided on the unidirectional input path of the amplifier a. The resistance of the pull-up resistor R12 is 2M, and the resistance of the pull-down resistor R16 is 10K. The amplifier A can be in a more stable working state through the reference voltage circuit.

The type of the amplifier A in the amplifying circuit is TP1252.

The IV conversion circuit comprises an amplifier B connected with the receiving diode, wherein the same-direction input end and the reverse-direction input end of the amplifier B are bridged at two ends of the receiving diode, the reverse-direction input end of the amplifier B is connected with the cathode of the receiving diode, and the same-direction input end of the amplifier B is connected with the anode of the receiving diode.

The communication circuit is a 485 communication circuit.

The main controller adopts an MCU processor, and the model is STM32.

Example 6

The fluorescent membrane comprises a carrier layer, an adhesive layer, a fluorescent layer and a fluorescent protective layer which are arranged in sequence. In use, the carrier layer is adjacent to the excitation light source and the reference light source.

The preparation method of the fluorescent membrane comprises the following steps:

s1, selecting quartz glass or polyester sheets with light transmittance of more than or equal to 95% as a substrate, namely a carrier layer, wherein the diameter of the substrate is 14.5mm, the thickness of the substrate is 2mm, and soaking the substrate in 1mol/L NaOH for 24H before use to remove acidity;

s2, backwashing the substrate treated in the S1 with absolute ethyl alcohol for 2 times, backwashing with deionized water for 3 times, removing surface impurities, and drying in an oven at 50 ℃ for later use;

S4, after being inhaled, ingested or absorbed through skin, di (2-ethylhexyl) phthalate (DEHP), the di (2-ethylhexyl) phthalate is harmful to the body and has a stimulating effect on the skin, and vapor or smoke of the di (2-ethylhexyl) phthalate has a stimulating effect on eyes, mucous membranes and upper respiratory tracts. Contact can cause gastrointestinal dysfunction. Uniformly coating the glue layer material prepared in the step (S3) on the substrate treated in the step (S2) by using a spin coater;

S5, preparing a fluorescent indicator, selecting tris (4,7-biphenyl-1,10-phenanthroline) ruthenium dichloride (Ru (dpp) 3Cl 2) as a main material, and having the characteristics of being basically insoluble in water, long fluorescence life and high sensitivity;

the precursor is a simple TEOS gel film, and has large net-shaped holes with uneven pore size distribution, the indicator can be wrapped in the holes, the large net-shaped holes easily cause leakage of the embedded indicator, the pore size distribution is uneven, so that the gel is easy to generate uneven internal stress when being dried, and the film is cracked.

When a certain amount of dimethyl diethoxy silane DDS (the volume of DDS/TEOS is 1:2) is added into the precursor, the pore size inside the gel film is reduced, and the pore size distribution tends to be uniform. Because a large number of ((CH 3) 2 SI-O-) n cyclic molecules are formed in the DDS hydrolysis process, the cyclic molecules have the modification effects of filling gaps, reducing pore size and capillary stress, reducing gel shrinkage and the like. Thereby making the gel film less prone to cracking and having good flexibility, while the embedded indicator is more uniform and less prone to leakage.

Dissolving carbon black and metal powder in 200ml of toluene and 1ml of naphthol, and magnetically stirring for 1h; 30ul of sol is mixed for 5s at 200 r/min; 1000r/min,30s; and (5) uniformly spin-coating the substrate treated with the step (S5) for 5 seconds at 200r/min, and drying in an oven at 50 ℃.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A dissolved oxygen measuring device based on a fluorescence quenching method comprises a shell (1), wherein one end of the shell (1) is a detection end, and the other end of the shell is a tail end; the detection end is provided with a fluorescent diaphragm, and an excitation light source and a reference light source which correspond to the fluorescent diaphragm; the detection circuit is also included; it is characterized in that the preparation method is characterized in that,

the detection end of the shell (1) is fixedly connected with the diaphragm mounting part (2); a fixing piece (5) for mounting an electrical element is arranged in the detection end;

the fixing piece (5) is a block corresponding to the inner cavity of the shell (1), a receiving hole (51) is formed in the middle of the fixing piece (5), emission holes (52) are symmetrically formed in two sides of the receiving hole (51), and a sensor receiving end used for receiving fluorescence of a fluorescent film is arranged on one side, far away from the film mounting portion (2), of the receiving hole (51); two red light source and blue light source are placed respectively to emission hole (52) inside, place blue light source emission hole (52) orientation the one end of diaphragm installation department (2) is horn mouth (55), blue light facula and red light facula on the final fluorescent film piece are equal in horn mouth (55).

2. The device for measuring dissolved oxygen based on the fluorescence quenching method according to claim 1, wherein an axis extension line of the emission hole (52) intersects with an axis extension line of the receiving hole, the emission hole (52) comprises an installation part (521) for installing a light source component and a light path part (522) communicated with the installation part (521), the installation part (521) and the light path part (522) are both cylindrical passages, the light path part (522) and the installation part (521) are coaxial, the inner diameter of the light path part (522) is smaller than that of the installation part (521), a transition part (523) is arranged between the light path part (522) and the installation part (521), the transition part (523) is a frustum-shaped through hole, and two ends of the transition part (523) are respectively connected with the installation part (521) and the light path part (522);

the horn mouth (55) is arranged at the outer end of the light path part (522) of the emission hole (52) where the blue light source is located.

3. The dissolved oxygen measuring device based on the fluorescence quenching method according to claim 2, wherein a connecting member (204) is provided in the membrane mounting portion (2), and the membrane mounting portion (2) is fixedly connected to the fixing member (5) through the connecting member (204);

the connecting piece (204) is an annular plate body fixedly arranged on the inner wall of the cavity of the diaphragm mounting part (2), and the connecting piece (204) is arranged at one end, close to the fixing piece (5), in the diaphragm mounting part (2);

a plurality of through holes are uniformly distributed in a circumferential array on the plate body of the connecting piece (204), and the number of the through holes is even;

the fixing piece (5) is provided with a mounting hole (53) corresponding to the through hole on the connecting piece (204);

the diameter of an opening in the middle of the connecting piece (204) is smaller than or equal to the length of a connecting line between the receiving hole (51) and the outer side end of the transmitting hole (52).

4. The dissolved oxygen measuring device based on the fluorescence quenching method according to claim 1, wherein the diaphragm mounting portion (2) is a cylinder, and a plurality of notches (205) are formed in a circumferential array at the end portion of the diaphragm mounting portion (2);

a film head mounting device (6) corresponds to the notch (205), and the film head mounting device (6) is a hollow cylindrical block;

diaphragm head erector (6) inside baffle (61) that is provided with, baffle (61) include locking portion (62) with diaphragm head erector (6) inside cavity the internal diameter of locking portion (62) equals the external diameter of diaphragm installation department (2), just baffle (61) orientation one side of locking portion (62) be provided with a plurality of with stopper (63) that notch (205) correspond.

5. The fluorescence quenching method-based dissolved oxygen measurement device according to claim 1, wherein the detection circuit comprises a light source excitation circuit for serving as a detection light source, the light source excitation circuit comprises an excitation light source excitation circuit and a reference light source excitation circuit which are respectively electrically connected with the main controller and form a control loop;

the detection circuit further comprises an acquisition channel, wherein the acquisition channel comprises an IV conversion circuit, an isolated direct current circuit, a reference voltage circuit, an amplifying circuit and an ADC acquisition circuit which are sequentially connected; the ADC acquisition circuit is electrically connected with the input end of the main controller, the IV conversion circuit is electrically connected with the receiving diode, and the receiving diode receives optical signals fed back by the fluorescent sensitive touch.

6. The device for measuring dissolved oxygen based on fluorescence quenching method according to claim 5, wherein the isolation DC circuit and the reference voltage circuit are connected in series in the amplifier circuit in the same-direction input path of the amplifier A;

7. The fluorescence quenching method-based dissolved oxygen measurement device according to claim 6, wherein the IV conversion circuit comprises an amplifier B connected to the receiving diode, the same-direction input terminal and the reverse-direction input terminal of the amplifier B are connected across the two ends of the receiving diode, the reverse-direction input terminal of the amplifier B is connected to the cathode of the receiving diode, and the same-direction input terminal of the amplifier B is connected to the anode of the receiving diode.

8. The dissolved oxygen measurement device based on the fluorescence quenching method according to claim 1, wherein the fluorescence membrane comprises a carrier layer, an adhesive layer, a fluorescent layer and a fluorescence protection layer which are arranged in sequence.

9. The dissolved oxygen measurement device based on the fluorescence quenching method according to claim 8, wherein the preparation method of the fluorescence membrane is as follows:

s1, selecting quartz glass or polyester sheets with light transmittance of more than or equal to 95% as a substrate, namely a carrier layer, and soaking the substrate for 24H by using NaOH to remove acidity;

s2, backwashing the substrate treated in the S1 for 2 times by using absolute ethyl alcohol and 3 times by using deionized water to remove surface impurities, and drying the substrate in an oven for later use;

s3, dissolving polyvinyl chloride powder in tetrahydrofuran, and adding di (2-ethylhexyl) phthalate as a glue layer material;

s4, uniformly coating the glue layer material prepared in the S3 on the substrate treated in the S2 by using a spin coater;

s5, preparing a fluorescent indicator, wherein tris (4,7-biphenyl-1,10-phenanthroline) ruthenium dichloride is selected as a main material;

adding tris (4,7-biphenyl-1,10-phenanthroline) ruthenium dichloride into absolute ethyl alcohol, and uniformly mixing by ultrasonic waves to prepare a fluorescent indicator solution;

using liquid to rush 2ml of tetraethoxysilane and 1ml of trifluoropropyltrimethoxysilane or dimethyldiethoxysilane to be added into a 10ml round-bottom flask, then continuing to add deionized water and absolute ethyl alcohol, adding catalyst hydrochloric acid to adjust the pH value, covering, sealing, magnetically stirring, using a liquid gun to add a fluorescent indicator ethanol solution, ultrasonically stirring, placing in a light-shielding environment for aging, and spin-coating sol on a substrate obtained in the step S4; preparing a slide with a fluorescent indicator, and aging for more than 7 days in a dark place;

s6, preparing a fluorescent protective layer;

carbon black and noble metal powder are required to be selected;

dissolving the carbon black and the metal powder by using a toluene solution and naphthol, and magnetically stirring; and uniformly spin-coating the sol on the substrate treated by the S5, and drying in an oven.

10. The dissolved oxygen measurement device based on the fluorescence quenching method according to claim 9, wherein the fluorescence membrane is prepared by a method comprising:

s1, selecting quartz glass or polyester sheets with light transmittance of more than or equal to 95% as a substrate, namely the carrier layer, wherein the diameter of the carrier layer is 14.5mm, the thickness of the carrier layer is 2mm, and soaking the substrate for 24H by using 1mol/L NaOH to remove acidity;

s3, dissolving polyvinyl chloride powder in tetrahydrofuran, and adding di (2-ethylhexyl) phthalate as a glue layer material; the proportion is as follows: polyvinyl chloride powder: di (2-ethylhexyl) dicarboxylate: tetrahydrofuran = 10g:20g:100ml;

the spin coating method of S4 comprises the following steps: 60ul of glue layer solution is dripped in the middle of the carrier glass, 400R/M,5S;1500R/M,20S; taking out the materials in parallel after spin coating at 400R/M and 5S, and drying for 5 minutes at 50 ℃ in a dust-free environment;

adding 250mg of tris (4,7-biphenyl-1,10-phenanthroline) ruthenium dichloride into 100ml of absolute ethyl alcohol, and uniformly mixing by ultrasonic waves to prepare a fluorescent indicator solution;

using liquid to rush 2ml of tetraethoxysilane and 1ml of trifluoropropyltrimethoxysilane or dimethyldiethoxysilane to be added into a 10ml round-bottom flask, then continuously adding 0.234ml of deionized water and 1.25ml of absolute ethyl alcohol, adding a catalyst hydrochloric acid to adjust the PH to 1.2, covering and sealing the flask, magnetically stirring the flask for 1H, adding 0.5ml of a fluorescent indicator ethanol solution by using a liquid gun, ultrasonically stirring the mixture for 10 minutes, putting the mixture into a light-proof environment for aging for 48H, and aging 60ul of sol for 5s, 3000r/min and 30s according to the ratio of 500 r/min; uniformly spin-coating the substrate obtained in step S4 at a speed of 500r/min for 5S; preparing a slide with a fluorescent indicator, and aging for more than 7 days in a dark place;

s6, preparing a fluorescent protection layer;

1g of carbon black with the diameter of 50nm and 1g of one of metal powders with the diameter of Jin Yinbo nm of noble metal are required to be selected;