Optical oxygen sensing film for optical oxygen sensor and preparation method thereof

Abstract

The present invention provides an optical oxygen sensing film for an optical oxygen sensor, which is composed of an oxygen-sensitive fluorescent film and a light-isolating film; the oxygen-sensitive fluorescent film is composed of an oxygen-sensitive fluorescent element and a highly oxygen-permeable polymer carrier; the light-isolating film is composed of anti-biological contamination particles, carbon black particles and a highly oxygen-permeable polymer carrier. The present invention directly integrates copper with bactericidal efficacy into the oxygen sensing film, rather than making the copper into a mesh or sieve shape and placing it at the front end of the film, which can effectively avoid problems such as reduced response speed caused by clogging of the mesh protective cover.

Description

Technical Field

[0001] The invention belongs to the technical field of oxygen detection, and in particular relates to a method for preparing an anti-biological contamination type optical oxygen sensing film. Background Art

[0002] Oxygen is a key substance for maintaining life activities, so accurate detection of oxygen content is crucial to ensure life safety. In the past, people have developed a large number of sensing technologies for detecting oxygen content in gas and liquid phases. Among them, optical sensing technology based on the principle of fluorescence quenching has attracted widespread attention and application in online oxygen detection due to its characteristics of no oxygen consumption, strong anti-interference, fast response speed, and maintenance-free. The oxygen sensing membrane is the core component of the optical oxygen sensor, which is a key factor in determining the sensitivity, response speed, stability, service life and other performance of the sensor.

[0003] In biochemical applications such as sewage treatment and aquaculture, optical oxygen sensors often face serious biological contamination problems.

[0004] Biological contamination refers to the phenomenon that organisms in the measuring medium adhere to the surface of the oxygen sensor membrane, resulting in a significant decrease in the sensor's response speed and measurement accuracy.

[0005] To alleviate biofouling, existing solutions include regular manual cleaning of optical oxygen sensor membranes, mechanical brush automatic cleaning of oxygen sensor membranes, and adding a copper mesh protective cover to the front of the oxygen sensor membrane. However, these methods will cause other new problems during application, such as increased maintenance workload, damage to the oxygen sensor membrane, and clogging of the copper mesh protective cover. In order to reduce the maintenance workload and the use of anti-pollution auxiliary components, it is necessary to develop an anti-biofouling oxygen sensor membrane to achieve long-term and stable monitoring of oxygen in biochemical application scenarios. Summary of the invention

[0006] The purpose of the present invention is to develop an optical oxygen sensing film resistant to biological contamination and a preparation method thereof.

[0007] The technical solution provided by the present invention is: an optical oxygen sensing film for an optical oxygen sensor, which is composed of an oxygen sensitive fluorescent film and a light isolation film;

[0008] The oxygen-sensitive fluorescent film is composed of oxygen-sensitive fluorescent element and a highly oxygen-permeable polymer carrier;

[0009] The light isolation film is composed of anti-biological pollution particles, carbon black particles and a high oxygen permeability polymer carrier.

[0010] Furthermore, the oxygen-sensitive fluorescent substance is a metal ruthenium complex or a platinum complex.

[0011] Preferably, the oxygen-sensitive fluorescein is platinum octaethylporphyrin.

[0012] Furthermore, the above-mentioned high oxygen permeability polymer carrier is one or more of polydimethylsiloxane, polymethyl methacrylate cellulose derivatives, polystyrene, and fluorinated copolymers.

[0013] Preferably, the highly oxygen permeable polymer carrier is polydimethylsiloxane.

[0014] Further, the anti-biological contamination particles are 2 micron brass powder;

[0015] Preferably, the carbon black particles are 2 microns.

[0016] A method for preparing an optical oxygen sensing film for an optical oxygen sensor,

[0017] The optical oxygen sensing film is composed of a light isolation film and an oxygen sensitive fluorescent film;

[0018] The light isolation film is composed of carbon black particles, anti-biological contamination copper particles and a highly oxygen-permeable polydimethylsiloxane carrier;

[0019] The oxygen-sensitive fluorescent film is composed of a highly oxygen-permeable polydimethylsiloxane carrier and oxygen-sensitive fluorescent pigment;

[0020] The preparation steps of the optical oxygen sensing film are as follows;

[0021] (S1) Preparation of oxygen-sensitive fluorescent film stock solution: Weigh polydimethylsiloxane carrier and oxygen-sensitive fluorescent element, mix them thoroughly by mechanical stirring, and let stand to defoam to obtain oxygen-sensitive fluorescent film stock solution;

[0022] (S2) Preparation of oxygen sensitive fluorescent film: Spin coating the oxygen sensitive fluorescent film stock solution on a glass plate at a spin coating speed of 500 rpm for 3 min. After coating, place the glass plate in an oven at 100°C for 30 min to solidify the oxygen sensitive fluorescent film.

[0023] (S3) Preparation of light-shielding film stock solution: Weigh a certain amount of polydimethylsiloxane carrier, carbon black particles and brass particles, fully mix the carrier with the carbon black and copper particles by mechanical stirring, and let stand to defoam to obtain a light-shielding film stock solution;

[0024] (S4) Preparation of optical oxygen sensing film: Spread the shading film stock solution prepared in step 3 on the oxygen-sensitive fluorescent film prepared in step 2, and evenly cover the surface of the fluorescent film with the stock solution by spin coating. The spin coating speed is 200 rpm and the spin coating time is 3 min. After coating, bake it in an oven at 100°C for 30 min. The polydimethylsiloxane carrier is cured to obtain an optical oxygen sensing film with a double-layer structure.

[0025] The mass ratio of the optical polydimethylsiloxane carrier and the oxygen-sensitive fluorescein was 100:1.

[0026] The mass ratio of the optical polydimethylsiloxane carrier, the carbon black particles and the brass particles is 5:2:1.

[0027] The present invention prepares an oxygen sensor membrane that is resistant to biological attachment (anti-biological contamination) by doping micron copper particles with bactericidal effect into the oxygen sensor membrane. The membrane has the following advantages:

[0028] (1) No other anti-biological contamination auxiliary components (such as mechanical hanging brushes) are required, which simplifies the structure of the sensor and does not cause damage to the oxygen sensing membrane.

[0029] (2) Integrating the bactericidal copper directly into the oxygen sensing membrane instead of making the copper into a mesh or sieve shape and placing it at the front end of the membrane can effectively avoid problems such as reduced response speed caused by clogging of the mesh protective cover;

[0030] (3) Micron copper particles are embedded in a highly oxygen-permeable polymer carrier and will not leak into the environment to cause environmental risks (biotoxicity).

[0031] (4) The structure of the sensor is simplified, reducing the cost of sensor manufacturing and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the structure of the anti-biological contamination optical oxygen sensing membrane in Example 1;

[0033] Figure 2 Comparison of DO detection performance between anti-biofouling oxygen sensing membrane and oxygen sensing membrane without anti-biofouling function;

[0034] Figure 3 Long-term comparison test results of DO sensors with and without anti-biofouling membranes in sewage aeration tanks;

[0035] 1-light isolation film; 2-oxygen sensitive fluorescent film; 3-high oxygen permeability polymer carrier; 4-carbon black particles; 5-anti-biological contamination copper particles; 6-oxygen sensitive fluorescent element.

[0036] A-output curve of the DO sensor with an anti-biofouling oxygen sensor membrane; B-output curve of the DO sensor with and without an anti-biofouling oxygen sensor membrane. DETAILED DESCRIPTION

[0037] The present invention is further described below in conjunction with specific examples, but the present invention is not limited to the following examples. The methods described are conventional methods unless otherwise specified. The raw materials described can be obtained from public commercial channels unless otherwise specified.

[0038] Example 1. Preparation of optical oxygen sensing film

[0039] like Figure 1 As shown, the anti-biological contamination optical oxygen sensing film provided by the present invention is composed of a light isolation film 1 and an oxygen sensitive fluorescent film 2. The light isolation film is composed of carbon black particles 4, anti-biological contamination copper particles 5 and a highly oxygen permeable polydimethylsiloxane carrier 3; the oxygen sensitive fluorescent film is composed of a highly oxygen permeable polydimethylsiloxane carrier 3 and oxygen sensitive fluorescent element 6. The specific preparation method of the oxygen sensing film is as follows;

[0040] (1) Preparation of oxygen-sensitive fluorescent film stock solution: Weigh 5 g of polydimethylsiloxane carrier 3 (Dow Corning 184, main agent: curing agent = 10:1) and 0.05 g of oxygen-sensitive fluorescent pigment 6 (platinum octaethylporphyrin, purchased from Sigma Reagent Network), mix the carrier and oxygen-sensitive fluorescent pigment thoroughly by mechanical stirring, and let stand to defoam to obtain the oxygen-sensitive fluorescent film stock solution;

[0041] (2) Preparation of oxygen-sensitive fluorescent film: Spin the oxygen-sensitive fluorescent film stock solution onto a glass plate at a speed of 500 rpm for 3 min. After coating, place the glass plate in an oven at 100°C for 30 min to solidify the polydimethylsiloxane carrier to obtain an oxygen-sensitive fluorescent film.

[0042] (3) Preparation of a light-shielding film stock solution without anti-biological contamination function: Weigh 5 g of polydimethylsiloxane carrier 3 and 2 g of carbon black particles, fully mix the carrier and the carbon black particles by mechanical stirring, and let stand to defoam to obtain a light-shielding film stock solution;

[0043] (4) Preparation of a light-shielding film stock solution with anti-biological contamination function: Weigh 5 g of a polydimethylsiloxane carrier, 2 g of carbon black particles 4 and 1 g of copper particles, fully mix the carrier with the carbon black and copper particles by mechanical stirring, and let stand to defoam to obtain a light-shielding film stock solution;

[0044] (5) Preparation of oxygen sensing film: The light-shielding film stock solution prepared in steps 3 and 4 was spread evenly on the oxygen-sensitive fluorescent film prepared in step 2, and the stock solution was evenly covered on the surface of the fluorescent film by spin coating, with a spin coating speed of 200 rpm and a spin coating time of 3 min. After coating, it was placed in an oven at 100°C for 30 min. After the polydimethylsiloxane carrier was solidified, a double-layer optical oxygen sensing film was obtained, including an anti-biofouling oxygen sensing film and an oxygen sensing film without anti-biofouling function.

[0045] Example 2: Comparison of dissolved oxygen (DO) detection performance between anti-biofouling oxygen sensor membrane and oxygen sensor membrane without anti-biofouling function

[0046] The anti-biological contamination type oxygen sensor membrane and the oxygen sensor membrane without anti-biological contamination function provided in Example 1 were respectively pasted on the membrane caps of two DO sensors, and the phase difference values ​​under different dissolved oxygen concentrations were measured according to the following steps to draw the DO detection signal response curve.

[0047] (1) Place a 1L glass beaker containing 500ml of purified water in a constant temperature water bath at 20℃;

[0048] (2) Continuously expose oxygen standard gas (China Standard Material Network) with an oxygen saturation in the range of 0-100% to the sample in step 1 to prepare DO standard solutions of different concentrations;

[0049] (3) Place the DO sensor in a beaker and immerse it in aeration. After the sensor reading stabilizes, record the phase difference (DP) signal value of the sensor.

[0050] (4) Use the DO concentration value and the corresponding measured phase difference signal value to draw the DO detection signal response curve. Based on the signal response curve, evaluate the detection performance of different oxygen sensor membranes;

[0051] (5) The measurement results show that as the DO concentration increases, the phase difference between the anti-biofouling oxygen sensing membrane and the non-anti-biofouling oxygen sensing membrane gradually decreases, showing an obvious proportional relationship, so it can be used for quantitative detection of DO. In addition, the signal change range of the two membranes is similar, indicating that there is no obvious difference in DO detection performance between the anti-biofouling oxygen sensing membrane and the non-anti-biofouling oxygen sensing membrane.

[0052] Example 3: On-site comparison test of anti-biological contamination oxygen sensor membrane and oxygen sensor membrane without anti-biological contamination function

[0053] The anti-biological contamination type oxygen sensor membrane and the oxygen sensor membrane without anti-biological contamination function provided in Example 1 were respectively pasted on the optical DO sensor, and the sensors were tied together and placed in the sewage aeration tank for long-term comparative testing. The specific method is as follows:

[0054] (1) Install the DO sensor with anti-biofouling sensor membrane and the oxygen sensor membrane without anti-biofouling function in the aeration tank of the sewage treatment plant, and keep the membrane surface of the sensor at the same horizontal line (to prevent the uneven distribution of oxygen concentration in the solution from affecting the comparative test results).

[0055] (2) Use 4G RTU wireless transmission equipment to transmit the real-time measurement data of the oxygen sensor back and draw a real-time curve based on the measurement data;

[0056] (3) Compare the real-time measurement curves of DO sensors with anti-biofouling oxygen sensing membranes and oxygen sensing membranes without anti-biofouling functions, and evaluate the measurement performance of the two membranes in actual biochemical application scenarios;

[0057] (4) By comparing the real-time measurement curves, it was found that at the beginning of the comparative test (at this time, no organisms were attached to either membrane), the measurement values ​​of the DO sensor with the anti-biological contamination oxygen sensor membrane (output test curve A) and the oxygen sensor membrane without anti-biological contamination function (output test curve B) were almost consistent (before the vertical dotted line, curves A and B almost overlapped), indicating that both sensors can respond quickly to changes in DO concentration; as the comparative test time (microorganisms gradually attached to the oxygen sensor membrane), the DO sensor with the anti-biological contamination function oxygen sensor membrane gradually slowed down its response speed to changes in oxygen concentration, and was significantly slower than the DO sensor with the anti-biological contamination oxygen sensor membrane (after the vertical dotted line, curves A and B did not overlap). This result shows that the anti-biological contamination oxygen sensor membrane developed by the present invention can effectively reduce the attachment of microorganisms to the membrane surface, thereby ensuring the long-term stability, accuracy and response speed of the optical oxygen sensor in biochemical application scenarios.

[0058] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

Claims

1. A method for preparing an optical oxygen sensing film for an optical oxygen sensor, characterized in that: The optical oxygen sensing film is composed of a light isolation film and an oxygen sensitive fluorescent film; The light isolation film is composed of carbon black particles, anti-biological pollution particles and a highly oxygen-permeable polydimethylsiloxane carrier; The oxygen-sensitive fluorescent film is composed of a highly oxygen-permeable polydimethylsiloxane carrier and oxygen-sensitive fluorescent pigment; The polydimethylsiloxane carrier is Dow Corning 184, main agent: curing agent = 10:1; The oxygen-sensitive fluorescein is platinum octaethylporphyrin; The carbon black particles are 2 microns; The anti-biological contamination particles are 2 micron brass particles; The preparation steps of the optical oxygen sensing film are as follows; (S1) Preparation of oxygen-sensitive fluorescent film stock solution: weighing polydimethylsiloxane carrier and oxygen-sensitive fluorescent pigment, wherein the mass ratio of the polydimethylsiloxane carrier to the oxygen-sensitive fluorescent pigment is 100:1; The two are fully mixed by mechanical stirring, and the oxygen sensitive fluorescent membrane stock solution is obtained after standing to defoam; (S2) Preparation of oxygen sensitive fluorescent film: Spin coating the oxygen sensitive fluorescent film stock solution on a glass plate at a speed of 500 rpm for 3 min. After coating, the glass plate was placed in an oven at 100°C for 30 min to solidify and obtain an oxygen-sensitive fluorescent film; (S3) Preparation of optical isolation film stock solution: Weigh a certain amount of polydimethylsiloxane carrier, carbon black particles and brass particles, fully mix the carrier with the carbon black and brass particles by mechanical stirring, and let stand to defoam to obtain the optical isolation film stock solution; The mass ratio of the polydimethylsiloxane carrier, carbon black particles and brass particles is 5:2:1; (S4) Preparation of oxygen sensing film: Spread the light isolation film stock solution prepared in step 3 on the oxygen sensitive fluorescent film prepared in step 2, and evenly cover the surface of the fluorescent film with the stock solution by spin coating. The spin coating speed is 200 rpm and the spin coating time is 3 min. After coating, bake it in an oven at 100°C for 30 min. The polydimethylsiloxane carrier is cured to obtain an optical oxygen sensing film with a double-layer structure.

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