CN211426258U - Light stream accuse water body dissolved oxygen detector - Google Patents

Abstract

The utility model discloses a light stream accuse water body dissolved oxygen detector. The detector includes: a first PDMS sheet and a second PDMS sheet; printing a channel structure on the first PDMS sheet; the first PDMS sheet is arranged on the second PDMS sheet, and one side of the first PDMS sheet, which is printed with the channel structure, is contacted with the second PDMS sheet; the channel structure comprises a silver nano triangular synthesis module, a water sample pretreatment module and an optical detection module; the water sample pretreatment module is respectively communicated with the silver nano triangular synthesis module and the optical detection module; the silver nano triangular synthesis module is used for synthesizing silver nano triangular solution; the water sample pretreatment module is used for mixing and reacting the silver nano triangular solution with a tested sample to obtain a solution carrying tested information; the optical detection module is used for detecting the solution carrying the detected information to obtain the concentration of dissolved oxygen in the detected sample. The utility model discloses can be accurate high-efficient, economy and measure the dissolved oxygen in the ocean simply and conveniently.

Description

Light stream accuse water body dissolved oxygen detector

Technical Field

The utility model relates to a dissolved oxygen measures technical field, especially relates to a light stream accuse water body dissolved oxygen detector.

Background

Oxygen provides necessary biochemical environment for the survival of marine organisms, and is an indispensable material for marine organism activities. The monitoring of the dissolved oxygen in the ocean plays an important role in the quality evaluation of the marine ecosystem, the marine scientific experiment and the marine resource exploration. In addition, dissolved oxygen is also a key parameter for biochemical systems and chemical processes. Therefore, the understanding of the distribution of the oxygen concentration and the change of the oxygen content in the water body has important significance for understanding the key process of the water ecosystem, evaluating and controlling the self-purification capacity of the water body and predicting and preventing aquatic ecological disasters.

The traditional water quality detection method is to send a water sample to a laboratory for detection and analysis after sampling on site. The intermediate process of the water quality detection method is very complicated, the detection period is too long, and the water quality cannot be obtained in time. Therefore, the traditional water quality detection method has the defects of poor real-time performance, great waste of manpower, material resources, financial resources and time, and high error in water sample collection and pretreatment measurement.

Currently, the three main test methods commonly used are iodometry, electrode polarography (so-called Clark electrode method), and fluorescence lifetime method. Although the iodometry has a wide detection range and high detection accuracy, the iodometry is an early method for quantitatively analyzing dissolved oxygen, has the defects of complicated operation, long operation time and high professional requirement of operators, and is rarely used for field application. The electrode polarography is generally used for measuring dissolved oxygen in water, is simple and rapid, and has relatively low instrument price, but the existence of telluride, oil, carbonate and algae in a water sample can cause blockage and even damage to a gas permeable membrane, so that the method generally needs to continuously stir the water sample, replace an electrolyte solution and perform zero calibration by an iodometry method in the actual measurement process. The fluorescence lifetime method is a sensitive, simple and rapid method, but the price of the instrument is relatively high, and the detection range is limited.

In conclusion, how to measure the dissolved oxygen in the ocean accurately, efficiently, economically and simply becomes a problem to be solved urgently at present.

Disclosure of Invention

Based on this, there is a need for an optofluidic water dissolved oxygen detector that can measure dissolved oxygen in the ocean accurately, efficiently, economically, and easily.

In order to achieve the above object, the utility model provides a following scheme:

an optofluidic water-dissolved oxygen detector comprising: a first PDMS sheet and a second PDMS sheet; a channel structure is printed on the first PDMS sheet; the first PDMS sheet is arranged on the second PDMS sheet, and one side of the first PDMS sheet, which is printed with a channel structure, is contacted with the second PDMS sheet;

the channel structure comprises a silver nano triangular synthesis module, a water sample pretreatment module and an optical detection module; the water sample pretreatment module is respectively communicated with the silver nano triangular synthesis module and the optical detection module; the silver nano triangular synthesis module is used for synthesizing a silver nano triangular solution; the water sample pretreatment module is used for mixing and reacting the silver nano triangular solution with a tested sample to obtain a solution carrying tested information; the optical detection module is used for detecting the solution carrying the detected information to obtain the concentration of dissolved oxygen in the detected sample;

the silver nano-triangular synthesis module comprises a first fluid inlet part, a first mixing part and a first reaction part; the first fluid inlet part is used for injecting a plurality of first reaction solutions into the first mixing part; the first mixing part is a channel composed of a plurality of fold line structures, and is used for mixing a plurality of first reaction solutions; the first reaction part is a channel consisting of a plurality of serpentine structures, and is used for reacting a plurality of first reaction solutions to obtain the silver nano triangular solution; the plurality of first reaction solutions include a silver nitrate solution, a sodium citrate solution, a hydrogen peroxide solution, and a sodium borohydride solution;

the water sample pretreatment module comprises a second fluid inlet part, a second mixing part and a second reaction part; the second fluid inlet part is used for injecting the silver nano triangular solution, the tested sample and a plurality of second reaction solutions into the second mixing part; the second mixing part is a channel composed of a plurality of fold line structures, and is used for mixing the silver nano triangular solution, the sample to be tested and a plurality of second reaction solutions; the second reaction part is a channel consisting of a plurality of serpentine structures, and is used for enabling the silver nano triangular solution, the sample to be detected and a plurality of second reaction solutions to react to obtain the solution carrying the information to be detected; the plurality of second reaction solutions comprise a glucose oxidase solution and a glucose solution;

the optical detection module comprises a liquid absorption pool and an optical fiber access port; the liquid absorption tank is communicated with the second reaction part; the optical fiber access port is used for being connected with a spectrometer system through a multimode optical fiber; the multimode optical fiber is used for guiding continuous white laser into the liquid absorption pool, and the continuous white laser irradiates the solution carrying the detected information to form an optical signal; the optical signal is transmitted to the spectrometer system through the multimode optical fiber; the spectrometer system is used to determine the dissolved oxygen concentration in the sample under test.

Optionally, the first fluid inlet portion comprises four fluid inlets, namely a first fluid inlet, a second fluid inlet, a third fluid inlet and a fourth fluid inlet; the four fluid inlets are respectively connected with corresponding micro-injection pumps; the micro injection pump is used for controlling the injection flow rate of the corresponding fluid inlet;

the first fluid inlet is used for injecting the silver nitrate solution; the second fluid inlet is used for injecting the sodium citrate solution; the third fluid inlet is used for injecting the hydrogen peroxide solution; the fourth fluid inlet is for injecting the sodium borohydride solution.

Optionally, the first mixing portion includes two groups of turning channels, namely a first turning channel and a second turning channel;

the starting point of the first broken line rotary channel is respectively communicated with the first fluid inlet, the second fluid inlet and the third fluid inlet, and the terminal point of the first broken line rotary channel is communicated with the fourth fluid inlet; the start point of the second fold-line turning channel is communicated with the fourth fluid inlet, and the end point of the second fold-line turning channel is communicated with the start point of the first mixing section; the first fold line rotary channel is used for mixing the silver nitrate solution, the sodium citrate solution and the hydrogen peroxide solution to obtain a first mixed solution; the second fold line rotary channel is used for mixing the first mixed solution with the sodium borohydride solution.

Optionally, the second fluid inlet portion comprises three fluid inlets, namely a fifth fluid inlet, a sixth fluid inlet and a seventh fluid inlet; the three fluid inlets are respectively connected with corresponding micro-injection pumps; the micro injection pump is used for controlling the injection flow rate of the corresponding fluid inlet;

the fifth fluid inlet is used for injecting the tested sample; the sixth fluid inlet is for injecting the glucose oxidase solution; the seventh fluid inlet is for injecting the glucose solution.

Optionally, the second mixing portion includes two groups of turning channels, namely a third turning channel and a fourth turning channel;

a starting point of the third broken line rotary channel is communicated with the fifth fluid inlet, the sixth fluid inlet and the seventh fluid inlet respectively, and an end point of the first broken line rotary channel is communicated with an end point of the first mixing part and a starting point of the fourth broken line rotary channel; the terminal point of the fourth broken line rotary channel is communicated with the starting point of the second mixing part; the third linear rotary channel is used for mixing the sample to be measured, the glucose oxidase solution and the glucose solution to obtain a second mixed solution; the fourth broken line rotary channel is used for mixing the second mixed solution with the silver nano triangular solution.

Optionally, the optical detection module further comprises a fluid outlet;

the fluid outlet is communicated with the liquid absorption pool and is used for enabling the solution carrying the detected information to flow out to a waste liquid bottle.

Optionally, each fluid inlet is connected with a corresponding micro-injection pump sequentially through a stainless steel needle, a capillary silicone tube and an injector;

one end of the stainless steel needle head is inserted into the fluid inlet, and the other end of the stainless steel needle head is connected with one end of the capillary silicone tube; the other end of the capillary silicone tube is connected with the injector; the injector is arranged on the micro injection pump; the micro-injection pump is used for controlling the injection flow rate of the injector.

Optionally, the spectrometer system includes a spectrometer and a CCD camera;

the spectrometer is connected with the multimode optical fiber and is used for receiving the optical signal and separating the optical signal according to wavelength to obtain a separated optical signal; the CCD camera is connected with the spectrograph and is used for detecting the separated optical signals to obtain a spectrum; the spectrum is used to determine the dissolved oxygen concentration in the sample being tested.

Compared with the prior art, the beneficial effects of the utility model are that:

the utility model provides a light stream accuse water body dissolved oxygen detector, include: a first PDMS sheet and a second PDMS sheet; printing a channel structure on the first PDMS sheet; the first PDMS sheet is arranged on the second PDMS sheet, and one side of the first PDMS sheet, which is printed with the channel structure, is contacted with the second PDMS sheet; the channel structure comprises a silver nano triangular synthesis module, a water sample pretreatment module and an optical detection module; the water sample pretreatment module is respectively communicated with the silver nano triangular synthesis module and the optical detection module; the silver nano triangular synthesis module is used for synthesizing silver nano triangular solution; the water sample pretreatment module is used for mixing and reacting the silver nano triangular solution with a tested sample to obtain a solution carrying tested information; the optical detection module is used for detecting the solution carrying the detected information to obtain the concentration of dissolved oxygen in the detected sample. The utility model discloses can be accurate high-efficient, economy and measure the dissolved oxygen in the ocean simply and conveniently.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without inventive labor.

FIG. 1 is a schematic structural diagram of an optical flow control water dissolved oxygen detector according to embodiment 1 of the present invention;

FIG. 2 is a schematic view of a channel structure in the optical flow control water dissolved oxygen detector according to embodiment 1 of the present invention;

fig. 3 is an angle schematic view of the broken-line revolving channel according to embodiment 1 of the present invention;

fig. 4 is a schematic structural diagram of an optical flow control water dissolved oxygen detector according to embodiment 2 of the present invention;

FIG. 5 is a graph showing the change of the measured spectrum curve and the corresponding relationship between the peak shift of SPR (Delta lambda) and the DO concentration at different dissolved oxygen concentrations in example 2 of the present invention; wherein FIG. 5(a) is a graph showing changes in measured spectral curves at different dissolved oxygen concentrations; FIG. 5(b) is a graph showing the relationship between the SPR peak shift (. DELTA.. lamda.) and the DO concentration when the flow ratio (R) of the nanoprism solution to the water sample is fixed to 1 and the pH of the water sample is fixed to 8; FIG. 5(c) is another linear map obtained between SPR peak displacement and DO concentration by varying the fluence ratio R.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative work belong to the protection scope of the present invention.

In order to make the above objects, features and advantages of the present invention more comprehensible, the present invention is described in detail with reference to the accompanying drawings and the detailed description.

Example 1

Fig. 1 is a schematic structural diagram of an optical flow control water dissolved oxygen detector according to embodiment 1 of the present invention. Referring to fig. 1, an embodiment of an optofluidic water-dissolved oxygen detector includes: a first PDMS sheet and a second PDMS sheet; a channel structure is printed on the first PDMS sheet; the first PDMS sheet is arranged on the second PDMS sheet, and one side of the first PDMS sheet, which is printed with a channel structure, is in contact with the second PDMS sheet.

Fig. 2 is a schematic view of a channel structure in the optical flow control water dissolved oxygen detector according to embodiment 1 of the present invention. Referring to fig. 1-2, the channel structure includes a silver nano-triangle synthesis module 1, a water sample pretreatment module 2, and an optical detection module 3; the water sample pretreatment module 2 is respectively communicated with the silver nano triangular synthesis module 1 and the optical detection module 3; the silver nano triangular synthesis module 1 is used for synthesizing a silver nano triangular solution; the water sample pretreatment module 2 is used for mixing and reacting the silver nano triangular solution with a tested sample to obtain a solution carrying tested information; the optical detection module 3 is used for detecting the solution carrying the detected information to obtain the concentration of dissolved oxygen in the detected sample.

The silver nano-triangular synthesis module 1 comprises a first fluid inlet part, a first mixing part and a first reaction part 4; the first fluid inlet part is used for injecting a plurality of first reaction solutions into the first mixing part; the first mixing part is a channel composed of a plurality of fold line structures, and is used for mixing a plurality of first reaction solutions; the first reaction part 4 is a channel composed of a plurality of serpentine structures, and the first reaction part 4 is used for reacting a plurality of first reaction solutions to obtain the silver nano triangular solution; the plurality of first reaction solutions include a silver nitrate solution, a sodium citrate solution, a hydrogen peroxide solution, and a sodium borohydride solution.

The water sample pretreatment module 2 comprises a second fluid inlet portion, a second mixing portion, and a second reaction portion 55; the second fluid inlet part is used for injecting the silver nano triangular solution, the tested sample and a plurality of second reaction solutions into the second mixing part; the second mixing part is a channel composed of a plurality of fold line structures, and is used for mixing the silver nano triangular solution, the sample to be tested and a plurality of second reaction solutions; the second reaction part 5 is a channel composed of a plurality of serpentine structures, and the second reaction part 5 is used for enabling the silver nano triangular solution, the sample to be detected and a plurality of second reaction solutions to react to obtain the solution carrying the information to be detected; the plurality of second reaction solutions includes a glucose oxidase solution and a glucose solution. Under natural conditions, the Dissolved Oxygen (DO) concentration is well below 20 mg/L. In this example, sufficient or excess glucose solution is required to achieve accurate detection of DO in the water, and at least 0.625mmol glucose is required for 20mg DO. The content of Glucose Oxidase (GOD) solution is related to the reaction efficiency and reaction time. Considering the response time of the whole optofluidic system and the DO content in the actual seawater sample, the ratio of the flow rates of the GOD solution (10mg/ml), the glucose solution (10mM) and the sample to be tested was fixed at 1: 1: 10.

the optical detection module 3 comprises a liquid absorption cell 17 and an optical fiber access port 18; the liquid absorption tank 17 is communicated with the second reaction part 5; the optical fiber access port 18 is used for connecting with a spectrometer system through a multimode optical fiber; the multimode fiber is used for guiding continuous white laser into the liquid absorption pool 17, and the continuous white laser irradiates the solution carrying the detected information to form an optical signal; the optical signal is transmitted to the spectrometer system through the multimode optical fiber; the spectrometer system is used to determine the dissolved oxygen concentration in the sample under test. The specifications of the multimode optical fiber in the embodiment are as follows: the numerical aperture is 0.2, and the core diameter/outer diameter is 50um/125 um.

As an alternative embodiment, the first fluid inlet portion comprises four fluid inlets, namely a first fluid inlet 6, a second fluid inlet 7, a third fluid inlet 8 and a fourth fluid inlet 9; the four fluid inlets are respectively connected with the corresponding micro-injection pumps 22; the micro injection pump 22 is used for controlling the injection flow rate of the corresponding fluid inlet; the first fluid inlet 6 is used for injecting the silver nitrate solution; the second fluid inlet 7 is used for injecting the sodium citrate solution; the third fluid inlet 8 is used for injecting the hydrogen peroxide solution; the fourth fluid inlet 9 is for injecting the sodium borohydride solution.

The first mixing part comprises two groups of fold line rotary channels, namely a first fold line rotary channel 10 and a second fold line rotary channel 11; the starting point of the first meandering channel 10 is in communication with the first fluid inlet 6, the second fluid inlet 7 and the third fluid inlet 8, respectively, and the end point of the first meandering channel 10 is in communication with the fourth fluid inlet 9; the starting point of the second turning channel 11 is communicated with the fourth fluid inlet 9, and the end point of the second turning channel 11 is communicated with the starting point of the first mixing part; the first folding line rotary channel 10 is used for mixing the silver nitrate solution, the sodium citrate solution and the hydrogen peroxide solution to obtain a first mixed solution; the second fold line rotary channel 11 is used for mixing the first mixed solution with the sodium borohydride solution.

As an alternative embodiment, the second fluid inlet 7 portion comprises three fluid inlets, respectively a fifth fluid inlet 12, a sixth fluid inlet 13 and a seventh fluid inlet 14; the three fluid inlets are respectively connected with the corresponding micro-injection pumps 22; the micro injection pump 22 is used for controlling the injection flow rate of the corresponding fluid inlet; the fifth fluid inlet 12 is used for injecting the tested sample; the sixth fluid inlet 13 is for injecting the glucose oxidase solution; the seventh fluid inlet 14 is for injecting the glucose solution. The fluid entrance (size 700um), the design has 4 rows of rectangle permutation, and the size is 30um 75um, and its effect filters the solid debris in the water, and the bubble in the separation liquid simultaneously eliminates the influence to the mixing portion.

The second mixing part comprises two groups of fold line rotary channels, namely a third fold line rotary channel 15 and a fourth fold line rotary channel 16; the starting point of the third turning channel 15 is in communication with the fifth fluid inlet 12, the sixth fluid inlet 13 and the seventh fluid inlet 14, respectively, and the end point of the first turning channel 10 is in communication with the end point of the first mixing section and the starting point of the fourth turning channel 16; the terminal point of the fourth broken-line rotary channel 16 is communicated with the starting point of the second mixing part; the third linear rotation channel 15 is used for mixing the sample to be measured, the glucose oxidase solution and the glucose solution to obtain a second mixed solution; the fourth broken-line rotary channel 16 is used for mixing the second mixed solution with the silver nano-triangle solution. The setting of broken line gyration passageway for stranded liquid makes a round trip to change the flow direction, guarantees to reflect the abundant contact between the solution, and wherein the camber of broken line gyration passageway's corner is 80 um's circular structure, compares with non-chamfer structure, can guarantee the flow of liquid, avoids the production at dead angle. The angle between adjacent straight channels in the zigzag turning channel is 30 degrees or 330 degrees as shown in fig. 3. At this angle, sufficient mixing speed can be achieved without causing excessive flow resistance to the detector.

As an alternative embodiment, the optical detection module 3 further comprises a fluid outlet 19; the fluid outlet 19 is communicated with the liquid absorption pool 17, and the fluid outlet 19 is used for discharging the solution carrying the measured information to a waste liquid bottle 20.

As an alternative embodiment, each of the fluid inlets is connected to the corresponding micro-injection pump 22 sequentially through a stainless steel needle, a capillary silicone tube 21 and an injector; one end of the stainless steel needle is inserted into the fluid inlet, and the other end of the stainless steel needle is connected with one end of the capillary silicone tube 21; the other end of the capillary silicone tube 21 is connected with the injector; the syringe is disposed on the micro syringe pump 22; the micro-injection pump is used for controlling the injection flow rate of the injector.

As an alternative embodiment, the spectrometer system comprises a spectrometer (Andor, Shamrock 303i) and a CCD camera. The spectrometer is connected with the multimode optical fiber and used for receiving the optical signal, and a grating structure in the spectrometer separates the optical signal according to wavelength to obtain a separated optical signal; the CCD camera is connected with the spectrograph and is used for detecting the separated optical signals to obtain a spectrum; the spectrum is used to determine the dissolved oxygen concentration in the sample being tested.

Specifically, the extinction spectrum of the eroded silver nanoparticles is detected by the CCD camera, and different dissolved oxygen concentrations in water cause different degrees of corrosion to the silver nanoparticles, and then influence the extinction spectrum, so that the SPR peak value shifts. By detecting the SPR peak shift, the concentration of dissolved oxygen in water will be determined.

The multimode optical fiber is an 50/125-scale multimode optical fiber and is fixed in an optical fiber access structure with the width of 115um, and the size of an access port is smaller than that of an optical fiber cladding due to certain elasticity of PDMS (polydimethylsiloxane), so that the optical fiber can be firmly fixed, and an incident light path and a signal receiving light path are ensured to be coaxial and to be stable. The front end of the optical fiber is provided with an air lens with curvature of 100um, and the air lens is used for realizing collimation of emergent light and convergence of incident signals.

The light flow control water body dissolved oxygen detector of the embodiment has the following advantages:

1. the silver nano-triangle synthesis module 1 is used for realizing the rapid on-chip synthesis of silver nano-triangles, wherein the geometric and optical characteristics can be controlled by rapidly and continuously adjusting the proportion of synthesis components. Flash chemistry, the rapid synthesis of nanoparticles in a single chip, can be achieved by rapid mixing of microfluidic channels and precise control of reactant flow.

2. The water sample pretreatment module 2 aims to realize quick and effective mixing. Sample water and detection reagents based on specific channel design and fluid dynamics. In this section, a water sample and reagents are injected into the system, effecting rapid mixing and reaction thereof in the channel, by which the dissolved oxygen in the water sample is converted to hydrogen peroxide by the action of glucose and glucose oxidase.

3. In the detection of dissolved oxygen in water, the mixing of liquid reaction components or water samples and reagents is crucial. Mixing efficiency affects not only the synthesis of nanoparticles, but also the response time of the system. Thus, a high density of broken line type mixing structures is introduced, ensuring that the reactants or samples are well mixed and react with each other.

A more specific example is provided below.

Example 2

The combination of micro-nano processing technology and microfluid technology promotes the rapid development of lab-on-a-chip technology. The microfluidics technology can accomplish the injection, transportation, mixing and detection of samples in micron-sized channels. It has the advantages of small volume, low cost, easy integration, low reagent consumption, low energy consumption, etc. It is widely used for biochemical detection and sensing. The micro-fluidic chip can be used for quickly detecting various biochemical indexes, can also realize sample pretreatment on the chip, and further realizes an integrated micro-nano sensor capable of quickly and accurately detecting the biochemical indexes. Among the numerous detection methods employed in "lab-on-a-chip", optical detection has a large amount of information bearing capacity, is resistant to electromagnetic interference, can realize remote and multi-channel detection, and has been widely used in biochemical detection. The intersection of modern optics and microfluidics has created emerging optofluidic technologies. Optofluidic technology is a new analytical field, focusing on the integration of optics and microfluidics, which offers many unique features to improve performance and simplify the design of microelectromechanical systems.

The metal nanoparticles with different shapes and sizes have great unique optical performance, so that the metal nanoparticles can be applied to a plurality of fields such as biosensors and nanomedicine. Studies have shown that there is a strong correlation between the properties of nanoparticles and their size and shape. Of all the metal nanoparticles, silver nanoparticles have stronger plasma interaction with light. In addition, the Localized Surface Plasmon Resonance (LSPR) peak wavelength of silver nanoparticles can be tuned throughout the visible and near infrared regions. Compared to spherical or quasi-spherical silver nanoparticles, the nanotriangles with anisotropic morphology show more LSPR bands due to reduced symmetry. The use of silver nanotriangles for biosensing and molecular detection has gained widespread attention.

Therefore, the present embodiment combines the optofluidic technology and the nanotechnology, and designs an optofluidic chip combining nanoparticle synthesis and spectral detection to realize accurate measurement of dissolved oxygen in a single chip, which has the same size as a coin. The light flow control water body dissolved oxygen detector in the embodiment mainly comprises three parts: 1) the silver nano triangular synthesis module comprises 4 fluid inlets for injecting silver nitrate, hydrogen peroxide, sodium citrate and sodium borohydride solution serving as reactants, and a broken line type (Z type) rapid fluid mixing structure and a snake-shaped liquid reaction part. 2) The water sample pretreatment module comprises 3 fluid inlets for injecting a water sample, a glucose solution and a glucose oxidase solution, the water sample is converged with the nano silver triangular colloidal solution synthesized by the first part after passing through the broken line type mixing structure, the nano silver triangular colloidal solution continuously flows through the broken line type structure to carry out rapid and sufficient mixing of liquid, and the serpentine structure completes sufficient reaction among reagents. 3) And finally, enabling the water sample carrying the dissolved oxygen information to flow into a third part: an optical detection module. The module consists of a capillary liquid absorption pool with the length of 1cm and 2 optical fiber access ports and is used for acquiring the water sample spectrum. 4) Finally, all the liquid flows out from the outlet and is recovered by a waste liquid bottle. The following describes the optical flow control water dissolved oxygen detector in this embodiment.

1. Method for preparing photo-fluidic water dissolved oxygen detector based on soft lithography process

Polydimethylsiloxane (PDMS) is the most widely used silicon-based organic polymer and is particularly known for its unusual rheological (or flow) properties. PDMS is optically transparent and is generally inert, non-toxic and non-flammable, making it one of the most common materials for flow delivery in microfluidic chips. The preparation process comprises the following steps: 1) a 40- μm layer of SU8 photoresist was spin coated onto a silicon wafer and after pre-baking, the master was exposed to UV light under a glass mask using a mask aligner. 2) A thick, chemically and thermally stable image is built on a silicon wafer as a template through the process of post-exposure baking, development and hard baking. 3) The microfluidic channels were molded using PDMS and sealed on a flat piece of PDMS after plasma oxidation, while the hydrophilicity of the PDMS surface was enhanced. The sealing method is plasma surface treatment bonding, and specifically comprises the following steps: the molded PDMS chip assembly and the glass slide coated with the PDMS thin layer were placed in a plasma cleaner and plasma treated for 2 minutes at 20W power. And taking out after the treatment is finished, and immediately reversely buckling the PDMS chip assembly printed with the channel in the middle of the glass slide coated with the PDMS thin layer. And ensuring that the distance between the edge of the upper PDMS chip main body and the edge of the lower glass slide is at least more than 5mm during fitting and sealing. After sealing, a closed channel of liquid is formed, and the reaction liquid and the sample liquid can only flow in from the inlet and flow out from the outlet. 4) The fabricated PDMS chips were stored in an oven at 75 ℃ for at least 1 hour to recover their hydrophobicity. 5) After inserting the fluid tubes and optical fibers into the microfluidic chip, the optofluidic chip prepares the wrist. The inlet and mixing channel widths were 100 μm and the reaction main channel width was 300 μm. The height of the microchannel is about 40 um.

The silver nanotriangles were synthesized dynamically in real time in an optofluidic chip according to standard synthesis procedures. In short, there are four fluid inlets in the synthesis module, see fig. 4, of which three (i1, i2, i3) are located in front of the high efficiency micromixer. The other inlet (i4) is designed in the middle of the mixer. Silver nitrate solution (AgNO)₃0.4mmol/L), sodium citrate solution (4mmol/L) and hydrogen peroxide solution (H)₂O₂0.6 wt%) were injected into the optofluidic device through inlets i1, i2, i3 at different flow rates (Qi1 ═ 1uL/min, Qi2 ═ 1.5uL/min, Qi3 ═ 0.5 uL/min).

Once they flow through the micromixer, the three streams mix completely quickly. In conventional synthesis methods, this step requires vigorous stirring for several minutes. This embodiment benefits from hydrodynamic and flash chemistry in microchannels, requiring only a few seconds for solution mixture and pre-reaction processes. Then sodium borohydride solution (NaBH) is injected through inlet i4₄8mmol/L) and a flow rate of 0.5 uL/min. The on-chip synthesis of the silver nano-triangles is realized through the synthesis module, and the proportion of the synthesized components is rapidly and continuously adjusted. To control the geometric and optical characteristics of the silver nanotriangles. Flash chemistry can be achieved by rapid mixing in microfluidic channels and precise control of reactant flow, thus enabling rapid synthesis of nanoparticles in a single chip.

2. Process for dissolved oxygen sensing

First, a glucose oxidase-GOD (10mg/mL) and glucose (10mM) solution was injected into the pretreated seawater sample. The seawater sample was injected through inlet i5 at a flow rate Qi5 ═ 35uL/min, glucose oxidase-GOD and glucose solution were injected through inlets i6 and i7, respectively, at a flow rate Qi6 ═ 3.5uL/min and Qi7 ═ 3.5 uL/min. The pre-treatment process is done in a polyline (Z-shaped) microchannel. According to the chemical reaction formula

The DO is converted to H2O 2.

Then, the Ag nano triangular solution was flowed into the post-treatment seawater sample at a specific flow rate. The mixture solution is mixed and reacted with the microchannel. Ag nano triangle passing chemical formula

2Ag+H₂O₂→2Ag⁺+2OH^-

H in the sample₂O₂And (6) corroding.

Less than 10 seconds are required to complete the chemical reaction and obtain stable optical properties in the microchannel. The solution was then detected by a super continuous white laser (Fianium, whitlelase SC400) and the signal was received through a multimode fiber. Spectra were then obtained by a spectrometer system including a CCD (Andor, Newton 920) and an Andor's Shamrock imaging spectrometer (Andor, Shamrock 303 i). By detecting the extinction spectrum, the DO concentration in the seawater sample can be measured and confirmed.

Solutions of different dissolved oxygen concentrations can be obtained by adjusting the ratio of nitrogen-saturated liquid to oxygen-saturated liquid by adjusting the flow rates of the two pumps of the flow injection analyzer at 25 ℃. The change in the spectral curve was measured at different dissolved oxygen concentrations, as shown in fig. 5 (a). The flow ratio (R) of the nanoprism solution to the water sample was fixed to 1, the pH of the water sample was fixed to 8, and the correspondence between the SPR peak shift (Δ λ) and the DO concentration was as shown in fig. 5 (b). A linear relationship was formed between SPR peak shift and DO concentration. By varying the flow ratio R, another linear correspondence was obtained between SPR peak displacement and DO concentration, as shown in FIG. 5 (c). High reconfigurability is one of the biggest advantages of optofluidic systems. Continuous adjustment of the DO detection range from 0 to 32mg/L can be achieved dynamically in real time by simply adjusting the ratio (R) between the silver nanoprism flux and the water sample flux, measuring a solution with a dissolved oxygen concentration of 0.5mg/L every 5 minutes under defined experimental conditions. After 20 measurements, the standard deviation s was obtained as 0.04. And 3 signal-to-noise ratio is adopted, so that the detection limit of the system can reach D-0.64 ug/L.

Compared with the traditional detection mode, the light flow control water body dissolved oxygen detector in the embodiment has the advantages of high measurement precision (the detection limit reaches 0.64ug/L), less consumption of samples and reagents (100 microliter), rapid processing and detection process (20 seconds), small size (2 x 5 centimeters), low cost, parallel processing of samples, adjustable detection range (0-32mg/L), easiness in integration and the like. The detector can overcome the defects of the traditional equipment in practical application, and has important application prospect in the field of water environment monitoring.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other.

The principle and the implementation of the present invention are explained herein by using specific examples, and the above description of the embodiments is only used to help understand the method and the core idea of the present invention; meanwhile, for the general technical personnel in the field, according to the idea of the present invention, there are changes in the concrete implementation and the application scope. In summary, the content of the present specification should not be construed as a limitation of the present invention.

Claims (8)

1. An optofluidic water dissolved oxygen detector, comprising: a first PDMS sheet and a second PDMS sheet; a channel structure is printed on the first PDMS sheet; the first PDMS sheet is arranged on the second PDMS sheet, and one side of the first PDMS sheet, which is printed with a channel structure, is contacted with the second PDMS sheet;

the channel structure comprises a silver nano triangular synthesis module, a water sample pretreatment module and an optical detection module; the water sample pretreatment module is respectively communicated with the silver nano triangular synthesis module and the optical detection module; the silver nano triangular synthesis module is used for synthesizing a silver nano triangular solution; the water sample pretreatment module is used for mixing and reacting the silver nano triangular solution with a tested sample to obtain a solution carrying tested information; the optical detection module is used for detecting the solution carrying the detected information to obtain the concentration of dissolved oxygen in the detected sample;

the silver nano-triangular synthesis module comprises a first fluid inlet part, a first mixing part and a first reaction part; the first fluid inlet part is used for injecting a plurality of first reaction solutions into the first mixing part; the first mixing part is a channel composed of a plurality of fold line structures, and is used for mixing a plurality of first reaction solutions; the first reaction part is a channel consisting of a plurality of serpentine structures, and is used for reacting a plurality of first reaction solutions to obtain the silver nano triangular solution; the plurality of first reaction solutions include a silver nitrate solution, a sodium citrate solution, a hydrogen peroxide solution, and a sodium borohydride solution;

the water sample pretreatment module comprises a second fluid inlet part, a second mixing part and a second reaction part; the second fluid inlet part is used for injecting the silver nano triangular solution, the tested sample and a plurality of second reaction solutions into the second mixing part; the second mixing part is a channel composed of a plurality of fold line structures, and is used for mixing the silver nano triangular solution, the sample to be tested and a plurality of second reaction solutions; the second reaction part is a channel consisting of a plurality of serpentine structures, and is used for enabling the silver nano triangular solution, the sample to be detected and a plurality of second reaction solutions to react to obtain the solution carrying the information to be detected; the plurality of second reaction solutions comprise a glucose oxidase solution and a glucose solution;

the optical detection module comprises a liquid absorption pool and an optical fiber access port; the liquid absorption tank is communicated with the second reaction part; the optical fiber access port is used for being connected with a spectrometer system through a multimode optical fiber; the multimode optical fiber is used for guiding continuous white laser into the liquid absorption pool, and the continuous white laser irradiates the solution carrying the detected information to form an optical signal; the optical signal is transmitted to the spectrometer system through the multimode optical fiber; the spectrometer system is used to determine the dissolved oxygen concentration in the sample under test.

2. The optofluidic water dissolved oxygen detector of claim 1, wherein the first fluid inlet portion comprises four fluid inlets, a first fluid inlet, a second fluid inlet, a third fluid inlet, and a fourth fluid inlet; the four fluid inlets are respectively connected with corresponding micro-injection pumps; the micro injection pump is used for controlling the injection flow rate of the corresponding fluid inlet;

the first fluid inlet is used for injecting the silver nitrate solution; the second fluid inlet is used for injecting the sodium citrate solution; the third fluid inlet is used for injecting the hydrogen peroxide solution; the fourth fluid inlet is for injecting the sodium borohydride solution.

3. The photo-fluidic water dissolved oxygen detector of claim 2, wherein the first mixing portion comprises two sets of zigzag channels, a first zigzag channel and a second zigzag channel;

the starting point of the first broken line rotary channel is respectively communicated with the first fluid inlet, the second fluid inlet and the third fluid inlet, and the terminal point of the first broken line rotary channel is communicated with the fourth fluid inlet; the start point of the second fold-line turning channel is communicated with the fourth fluid inlet, and the end point of the second fold-line turning channel is communicated with the start point of the first mixing section; the first fold line rotary channel is used for mixing the silver nitrate solution, the sodium citrate solution and the hydrogen peroxide solution to obtain a first mixed solution; the second fold line rotary channel is used for mixing the first mixed solution with the sodium borohydride solution.

4. An optofluidic water dissolved oxygen detector as recited in claim 3, wherein the second fluid inlet portion comprises three fluid inlets, a fifth fluid inlet, a sixth fluid inlet, and a seventh fluid inlet; the three fluid inlets are respectively connected with corresponding micro-injection pumps; the micro injection pump is used for controlling the injection flow rate of the corresponding fluid inlet;

the fifth fluid inlet is used for injecting the tested sample; the sixth fluid inlet is for injecting the glucose oxidase solution; the seventh fluid inlet is for injecting the glucose solution.

5. The photo-fluidic water-dissolved oxygen detector of claim 4, wherein the second mixing portion comprises two sets of turning channels with folding lines, a third turning channel and a fourth turning channel;

a starting point of the third broken line rotary channel is communicated with the fifth fluid inlet, the sixth fluid inlet and the seventh fluid inlet respectively, and an end point of the first broken line rotary channel is communicated with an end point of the first mixing part and a starting point of the fourth broken line rotary channel; the terminal point of the fourth broken line rotary channel is communicated with the starting point of the second mixing part; the third linear rotary channel is used for mixing the sample to be measured, the glucose oxidase solution and the glucose solution to obtain a second mixed solution; the fourth broken line rotary channel is used for mixing the second mixed solution with the silver nano triangular solution.

6. The optofluidic water dissolved oxygen detector of claim 1, wherein the optical detection module further comprises a fluid outlet;

the fluid outlet is communicated with the liquid absorption pool and is used for enabling the solution carrying the detected information to flow out to a waste liquid bottle.

7. The optical flow control water dissolved oxygen detector according to claim 2, wherein each fluid inlet is connected with a corresponding micro-injection pump sequentially through a stainless steel needle, a capillary silicone tube and an injector;

one end of the stainless steel needle head is inserted into the fluid inlet, and the other end of the stainless steel needle head is connected with one end of the capillary silicone tube; the other end of the capillary silicone tube is connected with the injector; the injector is arranged on the micro injection pump; the micro-injection pump is used for controlling the injection flow rate of the injector.

8. The optofluidic water dissolved oxygen detector of claim 1, wherein the spectrometer system comprises a spectrometer and a CCD camera;

the spectrometer is connected with the multimode optical fiber and is used for receiving the optical signal and separating the optical signal according to wavelength to obtain a separated optical signal; the CCD camera is connected with the spectrograph and is used for detecting the separated optical signals to obtain a spectrum; the spectrum is used to determine the dissolved oxygen concentration in the sample being tested.

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