Infrared unidirectional light-trapping plate, manufacturing method, photobioreactor and photosynthetic bacterial culture method

Abstract

The application discloses an infrared one-way light-trapping plate, a manufacturing method, a photobioreactor and a photosynthetic bacterial culture method, and belongs to the technical field of microbiology devices. The infrared one-way light-trapping plate comprises, from outside to inside, an incident matching layer, a light-guiding base layer and a total reflection blocking layer. The incident matching layer comprises a base body and a bionic moth-eye nano array distributed on the outer surface of the base body. The light-guiding base layer is an optical medium, the refractive index of the optical medium is greater than the refractive index of the incident matching layer, and the refractive index of the total reflection blocking layer is lower than the refractive indexes of the light-guiding base layer and the inner medium. The application has the advantages of intercepting escaped light energy and eliminating interface reflection loss.

Description

Technical Field

[0001] This invention belongs to the field of microbiological device technology, and relates to a photobioreactor, particularly to an infrared unidirectional light trapping plate, a manufacturing method, a photobioreactor, and a method for culturing photosynthetic bacteria. Background Technology

[0002] Photosynthetic bacteria (PSBs) are a class of prokaryotic microorganisms with significant economic and environmental value, particularly the genus *Rhodopseudomonas*, which demonstrates great potential in treating high-concentration organic wastewater such as food processing wastewater, aquatic environment remediation, and the synthesis of high-value-added metabolites such as coenzyme Q10 and 5-aminolevulinic acid. To achieve the industrial-scale, low-cost application of photosynthetic bacteria, the ultimate goal is to directly cultivate cells at high densities (greater than 10 CFU / mL) from unfiltered food processing wastewater. However, under current technological conditions, this goal faces irreconcilable optical-physical contradictions and biological niche conflicts.

[0003] First, there is a contradiction between the light penetration limit and lateral light escape in high-turbidity systems. Food wastewater typically has high initial turbidity and contains a large number of large-molecule organic colloids. In unfiltered food wastewater, as cultivation progresses, the increase in bacterial concentration and the presence of existing particulate matter lead to a sharp increase in the system's optical density (OD value). At this point, the incident light not only undergoes strong absorption inside the photobioreactor but also high-frequency Mie scattering. In existing flat-plate or tubular photobioreactors, this intense multiple scattering results in a large number of photons not being captured by the bacteria but being backscattered into the air through the inner wall of the photobioreactor, i.e., system light escape. It is estimated that in high-turbidity systems with OD > 1.5, more than 30% of the effective photosynthetic radiation entering the photobioreactor will escape through the reactor wall. Existing technologies typically attempt to ensure central light intensity by reducing the thickness of the photobioreactor, i.e., the optical path length, but this not only significantly reduces the effective volume utilization of the equipment but also fails to prevent the escape loss of interfacial light energy.

[0004] Secondly, there is the risk of niche competition from other microorganisms and micro-regional thermal inactivation caused by the solar spectrum. To reduce light source costs, industrial cultivation often uses outdoor natural light or ordinary broad-spectrum white light. However, photosynthetic bacteria, especially Rhodopseudomonas, have their effective photosynthetic wavelengths concentrated in the near-infrared region of 700–900 nm under anaerobic / micro-aerobic conditions, while microalgae such as Chlorella and other heterotrophic bacteria commonly found in wastewater environments mainly absorb visible light in the 400–700 nm range. Using full-spectrum irradiation will lead to rapid algal proliferation and niche occupation, causing cultivation failure.

[0005] Furthermore, high-energy input in the visible light band can lead to strong localized heat accumulation at the high-density waste liquid interface. Once the temperature exceeds 35°C, it can easily cause thermal degradation of the pigment complex within Rhodopseudomonas bacteria, i.e., thermal inactivation. Existing technologies that use physical filters or external sunshades not only severely reduce the transmittance of infrared light from the target but also suffer from significant interfacial Fresnel reflection loss during high-angle incidence sunlight, such as at low elevation angles in the morning and evening.

[0006] To address these issues, those skilled in the art have attempted to coat the outer wall of the reactor with a metallic reflective film or add light guide plates or optical fibers inside. However, while the metallic reflective film blocks the escape of internal light, it also blocks the entry of external light, failing to achieve a balance between light transmission and light locking. Furthermore, traditional internal light guiding systems such as light guide columns are prone to biofilm formation, resulting in extremely high maintenance costs in the complex environment of food wastewater. Summary of the Invention

[0007] This invention provides an infrared unidirectional light trapping plate, a manufacturing method, a photobioreactor, and a method for cultivating photosynthetic bacteria, in order to overcome the shortcomings of existing photobioreactors in high-density culture systems and complex wastewater environments, such as low energy utilization, poor spectral selectivity, and severe light escape loss.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides an infrared unidirectional light trapping plate located between an outer medium and an inner medium, comprising, from the outside to the inside, an incident matching layer, a light guiding substrate layer, and a total internal reflection blocking layer; the incident matching layer includes a substrate and a biomimetic moth-eye nanoarray distributed on the outer surface of the substrate; the light guiding substrate layer is an optical medium, the refractive index of which is greater than that of the incident matching layer; the refractive index of the total internal reflection blocking layer is lower than that of the light guiding substrate layer and the inner medium.

[0009] To optimize the above technical solution, the specific measures also include: Furthermore, the incident matching layer is made of a resin doped with a narrow bandpass absorber dye; the bandpass width of the narrow bandpass absorber dye is 800~890 nm.

[0010] Furthermore, the doping amount of the narrow bandpass absorber dye is 0.3~0.8 wt%, preferably 0.5 wt%.

[0011] Furthermore, the narrow-band light-absorbing dye is a phthalocyanine pigment or a metal complex pigment.

[0012] Furthermore, the biomimetic moth-eye nanoarray is composed of cones with a height of 400-600 nm and a period of 200-300 nm.

[0013] Furthermore, the refractive index of the light-guiding substrate layer is 1.70~1.90.

[0014] Furthermore, the optical medium is flint glass or a transparent polymer.

[0015] Furthermore, the refractive index of the total reflection blocking layer is 1.29~1.31.

[0016] Furthermore, the material of the total reflection blocking layer is an amorphous perfluoropolymer, preferably Teflon AF series.

[0017] Furthermore, the inner surface of the total reflection blocking layer is hydrophobic, and the surface roughness Ra is less than 50 nm.

[0018] Furthermore, the thickness of the incident matching layer is 1~3 μm; the thickness of the light guiding substrate layer is 8~15 mm, preferably 10 mm; and the thickness of the total internal reflection blocking layer is 1~3 μm, preferably 1.5 μm.

[0019] Secondly, the present invention also provides a method for manufacturing the above-mentioned infrared unidirectional light trapping plate: on the outer surface of the light guiding substrate, the substrate and the biomimetic moth-eye nanoarray are prepared by nanoimprint lithography (NIL), and the imprinting adhesive is a resin doped with narrow-band light-absorbing dye; on the inner surface of the light guiding substrate, an amorphous perfluoropolymer solution is coated by dip-coating or precision spraying, and the solvent is heated to evaporate and solidify into a film to form the total reflection blocking layer.

[0020] Furthermore, when preparing the light-guiding substrate layer, the heating temperature is 150~170 ℃, preferably 160 ℃.

[0021] Thirdly, the present invention also provides a photobioreactor, which is a flat-plate photobioreactor, including a light-transmitting panel, wherein the light-transmitting panel is the aforementioned infrared unidirectional light-trapping plate, the outer medium is air, and the inner medium is a culture medium.

[0022] Fourthly, the present invention also provides a method for culturing photosynthetic bacteria: food wastewater is injected into the above-mentioned photobioreactor, photosynthetic bacteria are inoculated, and the mixture is cultured under natural light or a simulated full-spectrum light source.

[0023] Furthermore, the food wastewater is bean product wastewater.

[0024] The beneficial effects of this invention are as follows: I. This invention utilizes the inverted refractive index difference between a wastewater system (food wastewater with a refractive index of approximately 1.34) and a total internal reflection blocking layer (with a refractive index of 1.29~1.31) to construct an infrared photon trap. This structure forces large-angle scattered light rays that would normally escape outward due to Mie scattering under high turbidity (OD>1.5) to be totally internally reflected back into the culture system, thus extending the average residence time and effective collision path of photons within the reaction system. Compared to traditional transparent flat-plate photobioreactors, this effectively intercepts escaped light energy, improves light energy utilization efficiency, and solves the problem of photosynthetic stagnation caused by self-shading effects in high-density bacterial cultures.

[0025] II. This invention completely eliminates interface reflection loss by establishing an optical unidirectional conduction physical mechanism. Specifically, through the optical angle compression effect of a light-guiding substrate layer with a high refractive index, the problem of incident light being blocked at the total internal reflection blocking layer is avoided. Simultaneously, in conjunction with a biomimetic moth-eye nanoarray of the incident matching layer, not only is all-weather, ultra-wide-angle, high-efficiency light capture achieved, but the reflectivity of the incident interface is also controlled at an extremely low level, saving on costly mechanical solar tracking equipment.

[0026] Third, this invention achieves single-colony proliferation through spectral purification and physical heat protection. Specifically, this invention uses an incident matching layer to precisely absorb and filter visible light in the 400-700 nm wavelength range, cutting off the photomorphogenesis and energy uptake pathways of microalgae such as green algae and cyanobacteria. This allows the target *Rhodopseudomonas* to form an absolutely dominant ecological community in high-concentration food wastewater environments without fine sterilization or filtration of large molecular suspended matter, effectively controlling algae growth. Simultaneously, by isolating the high-energy input of visible light, the micro-regional heat load at the system interface is significantly reduced, protecting the activity of high-density bacterial cells from thermal degradation.

[0027] Fourth, the material of this invention possesses corrosion resistance and self-cleaning properties, enabling it to adapt to harsh food wastewater environments. Specifically, the total reflection barrier layer of this invention utilizes an amorphous perfluoropolymer, achieving total reflection optical function while also exhibiting strong chemical inertness, superhydrophobicity, and low surface energy physical properties. This allows it to withstand the acidic environment and corrosion from proteases and fatty acids in food wastewater for extended periods. Furthermore, it significantly weakens the adhesion of biofilm deposits formed on the inner wall of the photobioreactor by photosynthetic microorganisms secreting extracellular polymers (EPS), thereby significantly extending the continuous operation cycle and light transmission life of the photobioreactor and greatly reducing cleaning and maintenance costs.

[0028] V. The present invention features a simple process, low cost, and is suitable for large-scale application. Specifically, the light-trapping effect of the present invention is based on the hierarchical configuration of static physical materials. Compared with traditional solutions such as built-in light sources and external reflective films, the structure is simpler and does not require additional electrical energy to drive high-intensity compensation light. At the same time, high-density cultivation is achieved without changing the original physical properties of the wastewater, i.e., without the need for pretreatment such as ultrafine filtration, reducing upstream pretreatment energy consumption and costs, and effectively utilizing food wastewater to produce high-value-added photosynthetic bacteria products. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the hierarchical structure of an infrared unidirectional light trapping plate and the incident path of external light. Figure 2 This is a schematic diagram of the total internal reflection light-locking principle of the present invention in a high-turbidity wastewater environment; Figure 3 This is the test report for photosynthetic bacteria inoculant in Example 2; The labels in the attached figure are: 1, incident matching layer; 11, substrate; 12, biomimetic moth eye nanoarray; 2, light guiding substrate layer; 3, total reflection blocking layer. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 1 As shown, the present invention provides an infrared unidirectional light trapping plate, located between an outer medium and an inner medium, and comprising, from the outside to the inside, an incident matching layer 1, a light guiding substrate layer 2, and a total reflection blocking layer 3.

[0032] The incident matching layer 1 includes a substrate 11 and a biomimetic moth-eye nanoarray 12 distributed on the outer surface of the substrate 11. Based on the effective medium theory (EMT), the biomimetic moth-eye nanoarray 12 enables a continuous gradient change in refractive index from the outer medium (i.e., air, with a refractive index of approximately 1.0) to the light-guiding substrate 2. Specifically, the biomimetic moth-eye nanoarray 12 is composed of cones with a height of 400–600 nm and a period of 200–300 nm.

[0033] In some embodiments, the incident matching layer 1 is made of a resin doped with a narrow-bandpass absorbing dye with a bandpass width of 800-890 nm, thus limiting the transmission window of the incident matching layer 1 to the 700-950 nm wavelength band, thereby achieving an absorption or reflectance of over 90% for visible light in the 400-700 nm wavelength band. Specifically, the narrow-bandpass absorbing dye is a phthalocyanine pigment or a metal complex pigment. The doping amount of the narrow-bandpass absorbing dye is 0.3-0.8 wt%, preferably 0.5 wt%.

[0034] In some embodiments, the thickness of the incident matching layer 1 is 1~3 μm.

[0035] The light-guiding substrate 2 is an optical medium with a refractive index greater than that of the incident matching layer 1. The light-guiding substrate 2 utilizes its high refractive index to strongly deflect the incident light, achieving angular compression of the light beam.

[0036] In some embodiments, the refractive index of the light-guiding substrate 2 is 1.70 to 1.90.

[0037] In some embodiments, the optical medium is flint glass or a transparent polymer.

[0038] In some embodiments, the thickness of the light-guiding substrate 2 is 8 to 15 mm, preferably 10 mm.

[0039] The refractive index of the total reflection blocking layer 3 is lower than that of the light guide substrate layer 2 and the inner medium.

[0040] In some embodiments, the refractive index of the total internal reflection blocking layer 3 is 1.29 to 1.31.

[0041] In some embodiments, the material of the total reflection blocking layer 3 is an amorphous perfluoropolymer, preferably Teflon AF series.

[0042] In some embodiments, the inner surface of the total reflection blocking layer 3 is hydrophobic, and the surface roughness Ra is less than 50 nm.

[0043] In some embodiments, the thickness of the total reflection blocking layer 3 is 1~3 μm, preferably 1.5 μm.

[0044] The present invention also provides a method for manufacturing the above-mentioned infrared unidirectional light trapping plate: on the outer surface of the light guiding substrate layer 2, a substrate 11 and a biomimetic moth-eye nanoarray 12 are prepared using nanoimprint lithography (NIL), and the imprinting adhesive is a resin doped with narrow-band light-absorbing dyes. On the inner surface of the light guiding substrate layer 2, an amorphous perfluoropolymer solution is coated using a dip-coating method or a precision spraying method, and the solvent is heated to evaporate and solidify into a film to form a total reflection blocking layer 3.

[0045] In some embodiments, the heating temperature for preparing the light-guiding substrate 2 is 150~170 ℃, preferably 160 ℃.

[0046] The present invention also provides a photobioreactor, which is a flat-plate photobioreactor, including a light-transmitting panel, the light-transmitting panel being the aforementioned infrared unidirectional light-trapping plate, the outer medium being air, and the inner medium being a culture medium.

[0047] The present invention also provides a method for culturing photosynthetic bacteria: food wastewater is injected into the above-mentioned photobioreactor, photosynthetic bacteria are inoculated, and the mixture is cultured under natural light or a simulated full-spectrum light source.

[0048] In some implementations, the food wastewater is bean product wastewater.

[0049] The working principle of a photobioreactor containing an infrared unidirectional light trapping plate includes: Wide-angle capture phase of incoming light: such as Figure 1 As shown, when natural light or simulated full-spectrum light source enters from air (refractive index approximately 1.0) at a maximum incident angle, the maximum refraction angle after entering the light guide substrate layer 2 (refractive index 1.70~1.90) is approximately 36°. Since the refraction angle is much smaller than the critical angle for the light guide substrate layer 2 to enter the total internal reflection blocking layer 3 (refractive index 1.29~1.31), all externally incident light cannot trigger the total internal reflection condition and can penetrate the total internal reflection blocking layer 3 to enter the photobioreactor with 100% penetration.

[0050] The energy imprisonment stage of locking in light: such as Figure 2 As shown, within a culture medium with an OD greater than 1.5, photons, after being scattered by Mie scattering of particles, exhibit an isotropic propagation direction, i.e., an angle range of 0–90°. When the scattered light rays travel from the culture medium (refractive index approximately 1.34) to the total internal reflection retardation layer 3 (refractive index 1.29–1.31), the critical angle is approximately 74.2°. All scattered light rays with an incident angle greater than 74.2° are forcibly reflected back into the culture medium by total internal reflection. These photons, which typically escape due to backscattering in conventional photobioreactors, are trapped within the culture medium in the photobioreactor of this invention, significantly increasing the probability of collisions between photons and photosynthetic bacteria.

[0051] The infrared unidirectional light trapping plate solves the energy distribution imbalance problem under high-density cultivation through the optical black cavity effect. Specifically, the incident matching layer 1 pre-filters out the visible light band with extremely high energy density from natural light or simulated full-spectrum light sources, avoiding thermal inactivation at the high-density bacterial interface and eliminating heat accumulation. The trapped photons form a diffuse light field within the photobioreactor, effectively compensating for the decrease in the light compensation point caused by the self-shielding effect of the bacteria. Through unidirectional infrared light introduction, a pure infrared field is constructed inside the photobioreactor, completely suppressing competition from algae such as cyanobacteria and green algae from the energy source without the use of chemical reagents.

[0052] Example 1 This embodiment provides an infrared unidirectional light trapping plate with spectral selectivity, which is used as a light-transmitting panel (main light-receiving surface) in a flat-plate photobioreactor with a volume of 500L.

[0053] The infrared unidirectional light trapping plate, from the outside to the inside, comprises an incident matching layer 1, a light guiding substrate layer 2, and a total reflection blocking layer 3. The fabrication method is as follows: Preparation of light guide substrate 2: A 10 mm thick transparent polycarbonate (PC) modified plate or heavy flint glass is selected as the bearing substrate. The refractive index at a specific wavelength is measured by a refractometer to be 1.72. This thickness ensures the mechanical compressive strength at a capacity of 500 L.

[0054] Fabrication of the incident matching layer 1: On the light-facing outer surface of the light-guiding substrate layer 2, a substrate 11 and a biomimetic moth-eye nanoarray 12 were fabricated using nanoimprint lithography. This array consists of tightly packed conical protrusions with a height of approximately 500 nm and a bottom diameter of approximately 250 nm. During this process, 0.5 wt% of phthalocyanine pigment was doped into the resin used for imprinting, resulting in an average absorption rate of over 90% for visible light in the 400–700 nm wavelength range for the incident matching layer 1, while maintaining a transmittance of over 90% for the 750–900 nm near-infrared wavelength range. This nanoarray structure achieves a gradual matching of refractive indices between air and the light-guiding substrate layer 2, with a large-angle incident reflectivity of <2%.

[0055] Preparation of the total internal reflection blocking layer 3: A layer of Teflon AF 2400 solution was coated on the backlight side (i.e., the inner wall of the photobioreactor) of the light-guiding substrate layer 2 using a dip-coating or precision spraying method. After solvent evaporation and high-temperature curing at approximately 160 °C, a transparent coating with a thickness of approximately 1.5 μm was formed. Measurements showed that this coating had a refractive index of 1.29, a water droplet contact angle >115°, and a surface roughness Ra less than 30 nm, exhibiting excellent hydrophobic and antifouling properties.

[0056] Example 2 Using the photobioreactor of Example 1, high-density cultivation of Rhodopseudomonas was carried out using unfiltered soybean product wastewater as a substrate.

[0057] Wastewater from soybean products, which had only been filtered through a 40-mesh sieve to remove large soybean residue particles and had not undergone fine filtration, was injected into the photobioreactor of Example 1. This wastewater was rich in soluble protein, polysaccharides, and colloidal particles, with a measured refractive index of approximately 1.34 and high initial turbidity. After inoculation with Rhodopseudomonas inoculum, it was cultured under natural light. The inoculum size was 10%. The culture was carried out continuously for 96 hours.

[0058] The light-incident process is as follows: effective infrared light from natural light passes through the biomimetic moth-eye nanoarray 12 and enters the light-guiding substrate layer 2 at a refraction angle of less than 35.5°. Since this angle is much smaller than the critical angle of total internal reflection (approximately 48.6°) emitted from the light-guiding substrate layer 2 towards the total internal reflection blocking layer 3, the external light completely penetrates the total internal reflection blocking layer 3 and enters the soybean product wastewater. The black cavity light-locking process is as follows: as the cultivation proceeds, the concentration of bacterial cells and the original colloidal particles in the soybean product wastewater cause strong multiple scattering in the system. When the internal large-angle scattered light shines outward toward the total internal reflection blocking layer 3, based on the physical condition that the refractive index of the soybean product wastewater is greater than the refractive index of the total internal reflection blocking layer 3, scattered light with an incident angle greater than 74.2° triggers total internal reflection and is completely bounced back into the photobioreactor like hitting a mirror, achieving a surge in local photon density.

[0059] Comparative Example 1 This comparative example is basically the same as Example 2, except that the photobioreactor used is a traditional flat-plate photobioreactor, and the light-transmitting panel is an ordinary transparent acrylic plate with a refractive index of 1.49, without the addition of filters and special coatings.

[0060] Comparative Example 2 This comparative example is basically the same as Example 2, except that the photobioreactor used is a traditional flat-panel photobioreactor, the light-transmitting panel is an ordinary transparent acrylic plate with a refractive index of 1.49, and a commercial infrared transmission visible light cutoff film is attached to the outer surface.

[0061] The relevant performance of the culture process of Example 2, Comparative Example 1 and Comparative Example 2 was tested, including the light escape rate, effective photon quantum yield increment, maximum cell density (CFU / mL), percentage of miscellaneous algae at the end of the culture medium, biofilm attachment on the inner wall (by dry weight per unit area), and maximum temperature rise of the culture system, as measured by a surface radiometer in the back direction. The test results are shown in Table 1.

[0062] Table 1. Results of performance testing related to the cultivation process in Example 2, Comparative Example 1, and Comparative Example 2.

[0063] The test results show that Comparative Example 2 exhibits severe reflection at large incident angles, with a light escape rate exceeding 35%. Comparative Example 1, due to light-limited stasis in the mid-to-late stages, reaches a peak cell density of 3.5 × 10⁻⁶. 8 The concentration of CFU / mL was high, and a large-scale microalgae bloom led to culture failure. The highest temperature of the system during the culture period rose to +12.4 ℃, and the surface experienced significant thermal inhibition.

[0064] The bacterial cultured in Example 2 was tested, and the results are as follows: Figure 3As shown, the amino acid content in the bacterial agent is 52%, including 288.41 mg / L alanine, 138.76 mg / L aspartic acid, and 153.29 mg / L glycine. It has strong activity, and the activity after amplification is consistent with that of the first generation.

[0065] In this invention, unless otherwise stated, scientific and technical terms used herein have the meanings commonly understood by those skilled in the art. Furthermore, the reagents, materials, and procedures used herein are all widely used in the relevant fields.

[0066] Finally, it should be noted that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An infrared unidirectional light trapping plate, located between an outer medium and an inner medium, characterized in that: From the outside in, it consists of an incident matching layer, a light-guiding substrate layer, and a total internal reflection blocking layer. The incident matching layer includes a matrix and a biomimetic moth-eye nanoarray distributed on the outer surface of the matrix; The light-guiding substrate layer is an optical medium, and the refractive index of the optical medium is greater than the refractive index of the incident matching layer; The refractive index of the total internal reflection blocking layer is lower than that of the light guide substrate layer and the inner medium.

2. The infrared unidirectional light trapping plate according to claim 1, characterized in that: The incident matching layer is made of a resin doped with a narrow bandpass absorber dye; the bandpass width of the narrow bandpass absorber dye is 800~890 nm.

3. The infrared unidirectional light trapping plate according to claim 1, characterized in that: The biomimetic moth-eye nanoarray is composed of cones with a height of 400-600 nm and a period of 200-300 nm.

4. The infrared unidirectional light trapping plate according to claim 1, characterized in that: The refractive index of the light guide substrate is 1.70~1.90; The optical medium is flint glass or a transparent polymer.

5. The infrared unidirectional light trapping plate according to claim 1, characterized in that: The refractive index of the total internal reflection blocking layer is 1.29~1.31; The material of the total reflection blocking layer is an amorphous perfluoropolymer.

6. The infrared unidirectional light trapping plate according to claim 1, characterized in that: The inner surface of the total reflection blocking layer is hydrophobic, and the surface roughness Ra is less than 50 nm.

7. The infrared unidirectional light trapping plate according to claim 1, characterized in that: The thickness of the incident matching layer is 1~3 μm; The thickness of the light guide substrate layer is 8~15 mm; The thickness of the total reflection blocking layer is 1~3 μm.

8. The method for manufacturing an infrared unidirectional light-trapping plate as described in any one of claims 1 to 7, characterized in that: On the outer surface of the light-guiding substrate, the substrate and the biomimetic moth-eye nanoarray are prepared by nanoimprint lithography, and the imprinting adhesive is a resin doped with narrow-band light-absorbing dye. An amorphous perfluoropolymer solution is coated onto the inner surface of the light-guiding substrate using a dip-coating or precision spraying method. The solvent is then heated to evaporate and solidify into a film, forming the total reflection blocking layer.

9. A photobioreactor, a flat-plate photobioreactor, comprising a light-transmitting panel, characterized in that: The light-transmitting panel is an infrared unidirectional light-trapping plate as described in any one of claims 1 to 7, the outer medium is air, and the inner medium is a culture medium.

10. A method for culturing photosynthetic bacteria, characterized in that: Food wastewater is injected into the photobioreactor as described in claim 9, inoculated with photosynthetic bacteria, and cultured under natural light or a simulated full-spectrum light source.

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