Revolutionary UV-Emitting Glass

A group of researchers led by UMass Amherst engineers has created ultraviolet (UV) ray-emitting glass that can reduce 98% of biofilm from growing on surfaces in underwater environments. A biofilm is a slimy layer of microorganisms that grows on wet surfaces. “If you look down your sink drain and touch the inner side of it— that slimy substance is biofilm,” describes Mariana Lanzarini-Lopes, assistant professor of civil and environmental engineering, whose research lab created the UV ray-emitting glass. Her lab is focused on engineering platforms that enhance light transport and reactions for photon- driven water treatment, working at the interface of basic science and industry to create innovative and green technologies. 

Biofilms pose a significant issue for underwater applications. The United States Navy estimates that biofilms cost between $180 and $260 million annually, since biofilm growth on underwater surfaces increases a ship’s drag and subsequent fuel usage, as well as corrosion damage on ships or equipment. 

Current solutions for dealing with biofilms 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, Lanzarini- Lopes and her team developed biofilm-resistant glass using UVC radiation, which is the UV wavelength most effective at disinfecting. 

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Her lab has already demonstrated that UV side-emitting optical fiber can distribute UVC radiation in small channels— such as those found in medical equipment, home devices, and water storage and distribution systems—to inactivate pathogenic organisms and prevent bacteria growth on surfaces. 

“A lot of people know about UV for disinfecting surfaces, air, and water,” says Lanzarini-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. Light becomes weaker as it moves away from the source, making it difficult to cover large surface areas, and the UV waves can be disrupted by how murky the surrounding water is. The resulting uneven distribution of the UV light can give biofilm-forming microorganisms a foothold, leaving the whole surface vulnerable. 

The team’s solution is a silica-nanoparticle coating on the glass. The UV LED is connected to the cross-section of the glass, and as the UV light propagates, it is transferred from inside of the glass to the outside, using 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 UMass Amherst researchers, in partnership with the Florida Institute of Technology and the Office of Naval Research, submerged this UV-emitting glass in the waters of Port Canaveral, Florida for initial proof-of-concept testing for 20 days. Compared to untreated glass, this glass reduced visible biofilm growth by 98%, results that were reported in the journal Biofilm. 

Building on these promising initial findings, the team recently completed an extended 3-month field study that demonstrated even more compelling results. While control units became completely fouled within just 2 weeks, the UV- emitting glass units maintained minimal biofouling (biofilm formation) throughout the entire 3-month period, even when operating at only 50% UV on/off cycling. Most remarkably, the UV units preserved their transparency for the duration of the extended test, demonstrating the technology’s potential for long-term marine applications. 

Now that the team has proven that this glass effectively resists biofilm formation, they are excited to optimize their discovery: testing long-term applications, assessing any effects on the environment, and creating larger surface areas. They recently published a paper in Environmental Science & Technology on how different UV wavelengths affect biofilm-prevention performance using their device. 

One future avenue of exploration: “We’re also trying to prevent biofilm on camera lenses,” says Lanzarini-Lopes. “The main inhibitor 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.” 

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This application is already moving from laboratory to market through Optical Waters—Lanzarini-Lopes’ startup company—which is working to license the technology from UMass Amherst and is actively collaborating with customers to retrofit surfaces to be UV-emitting using the company’s patent- pending technology. 

“Light has tremendous potential to drive beneficial reactions while replacing toxic chemicals from being released into the environment,” reflects Lanzarini-Lopes. “By developing better methods to deliver light into complex geometries, our lab is unlocking new possibilities for environmental remediation and engineering applications.”