UMass Amherst-led team creates biofilm-resistant glass for marine environments
The invention prevents biofilm formation by 98% and is poised to help solve a major issue for the U.S. Navy
UNIVERSITY OF MASSACHUSETTS AMHERST
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THE GLASS TREATED WITH ULTRAVIOLET RAYS (INSIDE), HAD 98% LESS BIOFILM GROWTH THAN THE UNTREATED GLASS (OUTSIDE).
view moreCREDIT: LANZARINI-LOPES RESEARCH GROUP
AMHERST, Mass. – A group of researchers led by University of Massachusetts Amherst engineers have created ultraviolet (UV) rays-emitting glass that can reduce 98% of biofilm from growing on surfaces in underwater environments, as reported in the journal Biofilm.
Biofilm is a slimy layer of various types of microorganisms that grows on wet surfaces. “If you look down your sink and touch the inner side of it—that slimy substance is biofilm,” describes Mariana Lanzarini-Lopes, assistant professor of civil and environmental engineering at UMass Amherst, and a corresponding author on the paper.
Biofilm is a significant issue for underwater applications. The United States Navy estimates that biofilms cost its fleet between $180 and $260 million annually. Biofilm growth on all underwater surfaces increases a ship’s drag and subsequent fuel usage, as well as corrosion damage on ships or oceanographic equipment.
Biofilm can also fog up windows used for cameras and other sensing devices that rely on transparency, and transport non-native species across the seas.
Current solutions for dealing with biofilm rely on chemical agents like biocidal coatings to kill the organisms or nonstick coatings to prevent biofilms from attaching in the first place. However, these methods can have negative effects on the ecosystem and only last for a short duration.
As an alternative to these chemical methods the UMass Amherst team, with funding from the U.S. Office of Naval Research (ONR), developed biofilm-resistant glass using UVC radiation, the shortest and most effective at disinfecting wavelength of UV radiation. Lopes’s lab has already demonstrated that UV side-emitting optical fiber can distribute UVC radiation in small channels, like medical equipment (i.e. endoscopes, catheters and respirators), home devices (coffee makers and refrigerators) and water storage/distribution systems (pipes, bladders, membranes) to inactivate pathogenic organisms and prevent bacteria growth on surfaces.
“A lot of people know about UV for disinfecting surfaces, air and water,” says Lopes. “People started using it a lot more especially because it was really effective for disinfection of the SARS-CoV-2 virus.”
However, in an underwater environment, it’s not as simple as shining UV light onto glass. “We cannot use traditional light sources to distribute light evenly on the surface,” for several reasons, says Leila Alidokht, postdoctoral research associate in Lopes’s lab and lead study author. Light becomes weaker as it moves away from the source, making it difficult to cover large surface areas. The UV waves can also be disrupted by how murky the surrounding water.
Uneven distribution of the UV light gives biofilm-forming microorganisms a foothold and leaves the whole surface vulnerable: “If the biofilm can attach to a part of the surface, it can spread to other parts,” she adds.
The team’s solution is a silica-nanoparticle coating on the glass. “The UV LED is connected from the cross-section of the glass,” Alidokht describes. “As UV enters the glass, we scatter the UV from inside of the glass to the outside,” using these light-scattering nanoparticles. The silica does not absorb the UV rays. The waves continue to bounce off the nanoparticles and through the glass interior which enables an evenly “glowing” glass surface.
To test it, the researchers, in partnership with Florida Tech and the Navy, submerged this UV-emitting glass in the waters of Port Canaveral, Florida for 20 days. Compared to untreated glass, this glass reduced visible biofilm growth by 98%.
“Contrary to external UV irradiation technique, UV-emitting glass inhibits biofilm formation directly at the surface of interest—the surface itself serves as a UVC source,” says Alidokht.
She is excited that this discovery opens the door for diverse disinfection applications. “The developed technology can be used for disinfection of transparent surfaces such as windows of ships, flotation spheres and moored buoys, camera lenses and sensors for oceanographical, agricultural and water treatment applications,” she says.
The team has received a provisional patent for their discovery.
Now that the team has proven that this glass effectively resists biofilm formation (known as biofouling), they are excited to optimize their discovery: testing long-term applications, assessing any effects on the environment and creating larger surface areas.
Another future avenue of exploration: “We’re also trying to prevent biofilm on camera lenses,” adds Lopes. “The maininhibitor of the length of time for deployment [of underwater cameras] is biofouling, so as long as you can decrease the rate of biofouling, you can increase how long you deploy all this optical equipment.”
Because the glass has a silica nanoparticle coating, the UV waves bounce through the glass interior which enables an evenly “glowing” glass surface.
CREDIT
Lanzarini-Lopes research group
Lanzarini-Lopes (center) with Alidokht (right) and graduate research assistant, Athira Haridas (left)
CREDIT
Lanzarini-Lopes research group
JOURNAL
Biofilm
METHOD OF RESEARCH
Experimental study
SUBJECT OF RESEARCH
Not applicable
ARTICLE TITLE
UV emitting glass: A promising strategy for biofilm inhibition on transparent surfaces
ARTICLE PUBLICATION DATE
28-Feb-2024
COI STATEMENT
The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Mariana Lanzarini-Lopes reports a relationship with Optical Waters that includes: board membership, equity or stocks, and funding grants. Katrina Fitzpatrick reports a relationship with Optical Waters that includes: board membership, equity or stocks, and funding grants. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Sunrise to sunset, new window coating blocks heat — not view
UNIVERSITY OF NOTRE DAME
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RESEARCHERS AT THE UNIVERSITY OF NOTRE DAME HAVE DEVELOPED A NEW WINDOW COATING TO BLOCK HEAT-GENERATING ULTRAVIOLET AND INFRARED LIGHT AND ALLOW FOR VISIBLE LIGHT, REGARDLESS OF THE SUN’S ANGLE.
view moreCREDIT: UNIVERSITY OF NOTRE DAME
Windows welcome light into interior spaces, but they also bring in unwanted heat. A new window coating blocks heat-generating ultraviolet and infrared light and lets through visible light, regardless of the sun’s angle. The coating can be incorporated onto existing windows or automobiles and can reduce air-conditioning cooling costs by more than one-third in hot climates.
“The angle between the sunshine and your window is always changing,” said Tengfei Luo, the Dorini Family Professor for Energy Studies at the University of Notre Dame and the lead of the study. “Our coating maintains functionality and efficiency whatever the sun’s position in the sky.”
Window coatings used in many recent studies are optimized for light that enters a room at a 90-degree angle. Yet at noon, often the hottest time of the day, the sun’s rays enter vertically installed windows at oblique angles.
Luo and his postdoctoral associate Seongmin Kim previously fabricated a transparent window coating by stacking ultra-thin layers of silica, alumina and titanium oxide on a glass base. A micrometer-thick silicon polymer was added to enhance the structure’s cooling power by reflecting thermal radiation through the atmospheric window and into outer space.
Additional optimization of the order of the layers was necessary to ensure the coating would accommodate multiple angles of solar light. However, a trial-and-error approach was not practical, given the immense number of possible combinations, Luo said.
To shuffle the layers into an optimal configuration — one that maximized the transmission of visible light while minimizing the passage of heat-producing wavelengths — the team used quantum computing, or more specifically, quantum annealing, and validated their results experimentally.
Their model produced a coating that both maintained transparency and reduced temperature by 5.4 to 7.2 degrees Celsius in a model room, even when light was transmitted in a broad range of angles. The lab’s results were recently published in Cell Reports Physical Science.
“Like polarized sunglasses, our coating lessens the intensity of incoming light, but, unlike sunglasses, our coating remains clear and effective even when you tilt it at different angles,” Luo said.
The active learning and quantum computing scheme developed to create this coating can be used to design of a broad range of materials with complex properties.
JOURNAL
Cell Reports Physical Science
ARTICLE TITLE
Wide-Angle Spectral Filter for Energy-Saving Windows Designed by Quantum Annealing-Enhanced Active Learning
Researchers use smartphone screen to create 3D layered holographic images
Full-color 3D display method holds promise for augmented and virtual reality
OPTICA
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RESEARCHERS DEVELOPED A 3D FULL-COLOR DISPLAY METHOD THAT USES A SMARTPHONE SCREEN, RATHER THAN A LASER, TO CREATE HOLOGRAPHIC IMAGES. SHOWN ARE THEIR EXPERIMENTAL RESULTS, IN WHICH A CONTINUOUS TRANSITION FROM THE FIRST LAYER TO THE SECOND LAYER IS OBSERVABLE.
view moreCREDIT: RYOICHI HORISAKI, THE UNIVERSITY OF TOKYO
WASHINGTON — Researchers have developed a 3D full-color display method that uses a smartphone screen, rather than a laser, to create holographic images. With further development, the new approach could be useful for augmented or virtual reality displays.
Whether augmented and virtual reality displays are being used for gaming, education or other applications, incorporating 3D displays can create a more realistic and interactive user experience.
“Although holography techniques can create a very real-looking 3D representation of objects, traditional approaches aren’t practical because they rely on laser sources,” said research team leader Ryoichi Horisaki, from The University of Tokyo in Japan. “Lasers emit coherent light that is easy to control, but they make the system complex, expensive and potentially harmful to the eyes.”
In the Optica Publishing Group journal Optics Letters, the researchers describe their new method, which is based on computer-generated holography (CGH). Thanks to a new algorithm they developed, they were able to use only an iPhone and an optical component called a spatial light modulator to reproduce a 3D color image that consisted of two holographic layers.
“We believe that this method could eventually be useful for minimizing the optics, reducing costs and decreasing the potential harm to eyes in future visual interfaces and 3D display applications,” said Otoya Shigematsu, the paper’s first author. “More specifically, it has the potential to enhance the performance of near-eye displays, such as the ones being used in high-end virtual reality headsets.”
A more practical approach
Although CGH uses algorithms to produce images, the coherent light from a laser is typically required to display these holographic images. In a previous study, the researchers showed that spatiotemporally incoherent light emitted from a white chip-on-board light-emitting diode could be used for CGH. However, this setup required two spatial light modulators — devices that control the wavefronts of light — which is impractical because of their expense.
In the new study, the researchers developed a less expensive and more practical incoherent CGH method. “This work aligns with our laboratory’s focus on computational imaging, a research field dedicated to innovating optical imaging systems by integrating optics with information science,” said Horisaki. “We focus on minimizing optical components and eliminating impractical requirements in conventional optical systems.”
The new approach passes light from the screen through a spatial light modulator, which presents multiple layers of a full-color 3D image. Although this may seem simple, it required carefully modeling the incoherent light propagation process from the screen and then using this information to develop a new algorithm that coordinated the light coming from the device screen with a single spatial light modulator.
Holographic images from a smartphone
“Holographic displays that use low-coherence light could enable realistic 3D displays while potentially reducing costs and complexity,” said Shigematsu. “Although several groups, including ours, have demonstrated holographic displays using low-coherence light, we took this concept to the extreme by using a smartphone display.”
To demonstrate the new method, the researchers created a two-layer optical reproduction of a full-color 3D image by displaying one holographic layer on the screen of an iPhone 14 Pro and a second layer on a spatial light modulator. The resulting image measured a few millimeters on each side.
The researchers are now working to improve the technology so that it can display larger 3D images with more layers. Additional layers would make images look more realistic by improving spatial resolution and allowing objects to appear at several different depths, or distances, from the viewer.
Paper: O. Shigematsu, M. Naruse, R. Horisaki, “Computer-generated holography with ordinary display,” Opt. Lett., 49, 8 (2024).
DOI: doi.org/10.1364/OL.516005
First author Otoya Shigematsu is shown in the laboratory with the optical experiment setup used for the work.
CREDIT
Ryoichi Horisaki, The University of Tokyo
About Optics Letters
Optics Letters offers rapid dissemination of new results in all areas of optical science with short, original, peer-reviewed communications. Optics Letters accepts papers that are noteworthy to a substantial part of the optics community. Published by Optica Publishing Group and led by Editor-in-Chief Miguel Alonso, Institut Fresnel, École Centrale de Marseille and Aix-Marseille Université, France, University of Rochester, USA. For more information, visit Optics Letters.
About Optica Publishing Group
Optica Publishing Group is a division of Optica, Advancing Optics and Photonics Worldwide. It publishes the largest collection of peer-reviewed content in optics and photonics, including 18 prestigious journals, the society’s flagship member magazine, and papers from more than 835 conferences, including 6,500+ associated videos. With over 400,000 journal articles, conference papers and videos to search, discover and access, Optica Publishing Group represents the full range of research in the field from around the globe.
JOURNAL
Optics Letters
ARTICLE TITLE
Computer-generated holography with ordinary display
ARTICLE PUBLICATION DATE
2-Apr-2024
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