CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims the priority benefit of U.S. Provisional Patent App. No. 63/400,589 filed on August 24, 2022, the entire disclosure of which is incorporated by reference herein.

BACKGROUND

[0002] For many industries such as power plants, water treatment systems, and the food/beverage industries, biofouling is a very common problem that can cause numerous issues including contamination, pipe blockages, decreased membrane flux, and reduced heatexchanger efficiency. In the shipping industry, biofouling increases ship hull drag, corrosion, fuel consumption, and engine stress. In daily life, from the humidifier in the living room to the air conditioner in the gym, from the water tank in the kitchen to the washing machine in the bathroom, biofouling occurs virtually anywhere there is water present. Biofouling in such systems can result in unwanted grow th of microorganisms, plants, and/or algae that may cause odors and/or the spread of infectious diseases

SUMMARY

[0003] An illustrative antifouling tile includes a tile blank having a first surface and a second surface opposite the first surface. The antifouling tile also includes a plurality of photocatalytic particles mounted to the first surface of the tile blank. The antifouling tile further includes an ultraviolet (UV) light source mounted to the second surface of the tile blank. The UV light source activates the plurality of photocatalytic particles to prevent biofouling of the tile blank.

[0004] In an illustrative embodiment, the plurality of photocatalytic particles comprise TiCh particles. In another embodiment, the TiCh particles comprise anatase titania particles. In one embodiment, the tile blank is made from glass. In another illustrative embodiment, the tile includes a power source that provides power to activate the UV light source. In one embodiment, the UV light source comprises a UV light strip with a plurality of UV lights. In another embodiment, an edge of the tile blank includes a tongue or a groove to connect adj acent tiles to one another. In some embodiments, the plurality of photocatalytic particles are applied as part of a solution that includes ethanol. In an alternative embodiment, the plurality of photocatalytic particles are zinc oxide particles. In another embodiment, the plurality of photocatalytic particles comprise nanoparticles.

[0005] An illustrative method for forming an anti-biofouling surface includes applying a plurality of photocatalytic particles to a first surface of a tile blank. The method also includes mounting an ultraviolet (UV) light source to a second surface of the tile blank such that light from the UV light source activates the plurality of photocatalytic particles to prevent biofouling. The method can also include forming the tile blank as a ceramic sheet that has the first surface and the second surface opposite the first surface. In some embodiments, the ceramic sheet comprises glass.

[0006] In one embodiment, the method further includes forming a solution that includes the plurality of photocatalytic particles, and applying the solution to the first surface of the tile blank. In such an embodiment, the solution can include titanium dioxide photocatalytic particles and ethanol. In another embodiment, the UV light sources comprises a light strip with a plurality of UV lights that are distributed over the second surface of the tile blank. In one embodiment, the plurality of photocatalytic particles comprise anatase titania particles. The method can further include mounting a power source to the second surface of the tile blank, where the power source provides power to activate the UV light source. In an illustrative embodiment, the plurality of photocatalytic particles comprise nanoparticles. In an alternative embodiment, the plurality of photocatalytic particles are zinc oxide particles.

[0007] Other principal features and advantages of the invention will become apparent to those skilled in the art upon review of the following drawings, the detailed description, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Illustrative embodiments of the invention will hereafter be described with reference to the accompanying drawings, wherein like numerals denote like elements.

[0009] Fig. 1 A is a comparison of a bare glass surface and a TiO2 coated glass surface after sunlight exposure for 5 days in accordance with an illustrative embodiment.

[0010] Fig. IB is a comparison of a bare glass surface and a TiCh coated glass surface after UV light exposure for 5 days in accordance with an illustrative embodiment. [0011] Fig. 2A is a comparison of a black background TiCh coated surface in the dark after 5 days and a black background TiCh coated surface exposed to UV light for 5 days in accordance with an illustrative embodiment.

[0012] Fig. 2B is a comparison of a white background TiCh coated surface in the dark after 5 days and a white background TiCh coated surface exposed to UV light for 5 days in accordance with an illustrative embodiment.

[0013] Fig. 3 is a comparison showing a TiCh coated surface with UV light exposure after 5 days and a TiCh coated surface in the dark after 5 days in accordance with an illustrative embodiment.

[0014] Fig. 4 is a diagram showing an antifouling tile and various applications of the tile in accordance with an illustrative embodiment.

[0015] Fig. 5 is a flow diagram depicting operations performed to form an antifouling tile in accordance with an illustrative embodiment.

DETAILED DESCRIPTION

[0016] Long-term exposure to moisture and organic/biological material results in the formation of biofilms and other biofouling build-ups. The current ways to solve this problem have various disadvantages. For example, in the boating industry, biocides can be placed in hull paint to help prevent biofouling. However, such biocides usually are generally toxic to marine organisms. Ultrasonic antifouling methods, pulsed laser irradiation, and the use of high-energy acoustic pulses are other techniques that are sometimes used to help prevent biofouling. However, these techniques all require additional energy inputs to perform antifouling. Additionally, the aforementioned biofouling techniques are inefficient at actually preventing biofouling build-up. In an effort to overcome these problems in traditional biofouling prevention techniques, the inventors have developed passive, self-cleaning, and durable coatings that resist biofouling.

[0017] As discussed, traditional biofouling prevention solutions have various disadvantages like toxicity, additional energy inputs, and high energy-consumption. Described herein is an environmentally friendly, low-cost, and scalable anti-biofouling technique. Specifically, the inventors have developed a self-cleaning mechanism utilizing photocatalytic degradation induced by an embedded UV source that can energy' efficiently remove biofouling on a photocatalytic coating. The proposed system has applications that allow for improved material longevity, enhanced energy efficiency, and reduced operating costs. As discussed in more detail below, the proposed system utilizes photocatalysis to induce degradation of organic and biological material. This function involves the use of materials science and physical chemistry to expose a crystal face to ultraviolet (UV) radiation, thereby oxidizing the surface and killing contaminants on the surface.

[0018] The proposed methods and system can be used to prevent build-up of and/or to remove a film of a biological material from a surface. In an illustrative embodiment, photocatalytic particles are applied to a surface placed in a biologically contaminated environment such as under the sea or in the human body. An embedded UV light source is mounted underneath the coating and is used to expose the biofouled surface to UV radiation. Any type of UV light source may be used, such as a deuterium lamp, xenon lamp, mercury lamp, tungsten halogen lamp, tanning lamp, blacklight, laser, etc. The application of UV radiation triggers photocatalytic decomposition of organic and/or biological material from the coating, thereby preventing film formation and growth on the surface. The UV light source can be powered by one or more batteries, by one or more solar panels, one or more movement based energy harvesters, etc.

[0019] More specifically, the function of the coating is based on the photocatalytic decomposition of organic and biological material, meaning exposure to UV radiation creates surface oxidation, which degrades the surface contaminants. Titanium dioxide (i. e. , titania) has been shown to demonstrate such photocatalytic effects. The effect is dependent on the crystal structure, and it has been found that exposure of a plane of anatase titania creates a significant photocatalytic effect. Other crystal structures of titania, like rutile and brookite, produce this effect to a lesser degree and can be used in some embodiments. To create a surface coating with the highest anti-biofouling potential, maximizing photocatalytic potential is of utmost importance. Therefore, nanoparticles of anatase titania are used here, but the same anti-biofouling efficacy can be achieved with similar photocatalytic particles, including metal oxides like ZnO and MgO. Nanoscale particles are used to increase the surface area and exposure of the photoactive plane to UV radiation. Porous nanoscale scaffolds like aerated poly dimethylsiloxane (PDMS), hydrogels, or aerogels can also be infused with these particles and applied to a surface to further increase the surface area and enhance photocatalytic degradation. The photocatalytic surfaces with embedded UV light sources can be prepared in the form of tiles, patches, tubes, etc. that are based on 3D printed modules and a semiconductor manufacturing processes in one embodiment. Alternatively, any other fabrication techniques may be used.

[0020] Adhesion of the photoactive particles to the functional substrate can be achieved by thermal annealing, polymer adhesives, or similar methods. A UV light source is embedded underneath the coating, as shown in the drawings. As biological or organic material is deposited and grows on the surface, exposure of the coating to UV radiation (light) from the embedded UV radiation triggers degradation and a self-cleaning effect, thereby refreshing the functional surface to its original state.

[0021] Fig. 1 A is a comparison of a bare glass surface and a TiCh coated glass surface after sunlight exposure for 5 days in accordance with an illustrative embodiment. Fig. IB is a comparison of a bare glass surface and a TiCh coated glass surface after UV light exposure for 5 days in accordance with another illustrative embodiment. As shown in both Figs. 1A and IB, the TiO2 coated glass surface has significantly less biofouling buildup as compared to the bare glass surface. Fig. 2A is a comparison of a black background TiCh coated surface in the dark after 5 days and a black background TiCh coated surface exposed to UV light for 5 days in accordance with an illustrative embodiment. Fig. 2B is a comparison of a white background TiCh coated surface in the dark after 5 days and a white background TiCh coated surface exposed to UV light for 5 days in accordance with an illustrative embodiment. As shown in Figs. 2A and 2B, there is significantly less biofoulmg buildup on the surfaces that were exposed to UV light.

[0022] Fig. 3 is a comparison showing a TiCh coated surface with UV light exposure after 5 days and a TiCh coated surface in the dark after 5 days in accordance with an illustrative embodiment. In Fig. 3, the surfaces were merged in clean tap water for about 30 minutes. As shown, there is less biofouling buildup on the surface that was exposed to UV light, as compared to the surface left in the dark.

[0023] Fig. 4 is a diagram showing an antifouling tile and various applications of the tile in accordance with an illustrative embodiment. As shown, the tile includes TiCh particles applied to a glass surface. Alternatively particles other than TiCh may be used, and a surface other than glass may be used, such as another ceramic, fiberglass, etc. A UV light strip is mounted behind the glass surface (i.e., on the opposite side of the glass to which the TiCh particles are mounted. The tile can then be mounted on various surfaces such as a ship’s hull, a sink, a plumbing pipe, a washing machine drum, etc. The tiles can be mounted using an adhesive, fasteners (e.g., screws, rivets, etc.), clamps, etc. In an illustrative embodiment, the tiles can interconnect with one another using a snap lock system, tongue-and-groove system, etc. In such an embodiment, the edges of tiles mate with one another to form a seamless surface.

[0024] Fig. 5 is a flow diagram depicting operations performed to form an antifouling tile in accordance with an illustrative embodiment. As shown, 1.5 grams of TiCh particles stored in 14 grams of ethanol can be used to form a solution, which is poured into a spray gun or other dissemination device. Alternatively, different types/amounts of particles and/or a different amount/type of fluid may be used to form the solution. The spray gun is used to apply the solution to a first side of a glass tile blank. Alternatively, the tile blank can be made from marble, another ceramic, metal, fiberglass, plastic, etc. The tile is then slowly heated in an oven until it reaches a temperature of 350 degrees Celsius, and it is maintained at 350 degrees C for 3 hours. The tile is then slowly cooled down to room temperature. A UV light source is applied to a second side of the glass (or other material used to form the tile blank), as discussed herein.

[0025] As compared to traditional systems, the proposed system has a broader antifouling effect even in a dark environment due to the use of an embedded UV element. Also, when the UV lights are applied, the illumination that is exposed to the nearby environment is reduced due to the particle coverage, which is more environmentally friendly than traditional systems. Compared with other high-energy input method like pulsed laser irradiation, the proposed system utilizes much less energy input and costs less. Additionally, titanium dioxide is non-toxic and readily available. Titanium dioxide is already commonly produced and used primarily as a pigment in mass quantities, meaning there is a non-prohibitive cost of scaled-up manufacturing of these anti-biofouling coatings. Further, the titania coating is chemically inert, has low toxicity, and long-term stability.

[0026] Thus, described herein is an antifouling coating that is able to prevent the formation and growth of unwanted biofouling on surfaces of various applications. The proposed coating system is environmentally friendly, low-cost, and easy to make and apply. Anti-biofouling performance can be realized independent of daylight exposure and an embedded UV light source is highly focused on the coating, minimizing energy consumption. The proposed coatings can be used in numerous industries and systems such as the ship industry, for vehicles such as submarines, rockets, airplanes, cars/trucks, trains, etc., for home appliances such as washing machines, dishwashers, and refrigerators, for air conditioners, heat pumps, and other HVAC systems, for plumbing pipes, for humidifiers, in medical devices such as stents and joints, in the pharmaceutical industry, in power plant cooling towers, in the refrigeration/food industry, for solar panels, etc.

[0027] The word "illustrative" is used herein to mean serving as an example, instance, or illustration. Any aspect or design described herein as "illustrative" is not necessarily to be construed as preferred or advantageous over other aspects or designs. Further, for the purposes of this disclosure and unless otherwise specified, "a" or "an" means "one or more.”

[0028] The foregoing description of illustrative embodiments of the invention has been presented for purposes of illustration and of description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and as practical applications of the invention to enable one skilled in the art to utilize the invention in various embodiments and with various modifications as suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.