Nebraska U's new laser to facilitate manufacturing method of the future

The University of Nebraska –Lincoln’s Center for Electro-Optics and Functionalized Surfaces is now home to a first-of-its-kind laser in the United States to be used for a specialized method of surface modification.

This approach — called femtosecond laser surface processing — beams an ultrafast laser at a metal material, changing its micro- and nanoscale features and its chemistry. These changes confer properties conducive to a wide range of applications in space, defense, medicine and beyond.

Because it offers advantages over traditional surface modification methods, FLSP is considered a manufacturing method of the future and is an area in which Husker researchers have led the way for more than a decade. The new laser, purchased with funding from the Defense University Research Instrumentation Program, comes at a pivotal time in the field.

“The laser technology is advancing very rapidly right now,” said Craig Zuhlke, center co-director and associate professor of electrical and computer engineering. “It’s a very exciting time. This is going to become a manufacturing field because of the lasers that are now available.”

The new Tangor 300 laser produced by Amplitude will help Husker researchers overcome a major barrier to FLSP’s widespread industrial use: scalability. Though researchers have been functionalizing surfaces with lasers for about two decades, the complex methods and available technology allowed production of only tiny samples. Now, the university will be able to produce larger quantities of raw materials with tailored surface properties.

“The new laser will be able to functionalize about 50 times faster than we can right now,” said George Gogos, center co-director and Wilmer J. and Sally L. Hergenrader Professor of Mechanical and Materials Engineering. “There are members of the space and defense industries that are aware we have this laser, and there’s an interest for additional work, funding and collaborations because of this scalability.”

To harness this momentum, the researchers have launched a startup called Integrated Functionalized Materials. The company is in its infancy, but the team expects to draw significant interest based on the newfound ability to scale up production.

The latest acquisition is another high point for the Center for Electro-Optics and Functionalized Surfaces, which Dennis Alexander, professor emeritus of engineering, originally launched as the Center for Electro-Optics in 1987. Since 2015, it has received continuous base funding from the Office of Naval Research, an agency of the Department of Defense. It conducts additional research funded by the National Science Foundation, the Department of Energy’s Kansas City National Security Campus, Boeing, Textron Aviation and Honeywell, as well as funded collaborative work with five NASA centers. In total, the center has received about $13.5 million since 2014.

This success reflects the university’s unique multidisciplinary approach to FLSP research. The Center for Electro-Optics and Functionalized Surfaces is the only research group in the U.S. that unites experts from various disciplines involved in FLSP: laser-matter interactions, materials science, thermal management and chemistry, among others. In addition to Zuhlke and Gogos, Jeffrey Shield, Robert W. Brightfelt Professor of Mechanical and Materials Engineering, and Siamak Nejati, associate professor of chemical and biomolecular engineering, play major roles in the center. Ten additional Husker faculty, as well as external collaborators, regularly contribute.

“That’s our niche, nationwide,” Gogos said. “No one else has put such an interdisciplinary group together.”

This approach is key to unlocking the full potential of FLSP, which poses significant advantages over the paints and coatings traditionally used to modify metal surfaces. Manufacturing these coatings requires a complex multi-step process involving harmful chemicals; some of the coatings themselves contain toxic substances. And they’re a temporary solution — over time, the coatings peel off.

FLSP, by contrast, permanently and directly changes the physical and chemical properties of a metal in a single step. It doesn’t add extra layers on top of the base material: The micro- and nanoscale features are created on a very thin slice — about the thickness of a human hair — of the metal’s surface. And the laser pulses do not disturb the bulk material underneath that layer.

The process is also customizable. By tailoring the parameters of laser functions, researchers can optimize a surface for a wide variety of applications.

• Antimicrobial surfaces for the International Space Station: With NASA funding, Zuhlke is leading work to develop antimicrobial surfaces for the ISS’ next generation of heat exchangers. Heat exchangers control the station’s humidity, which is important to maintaining equipment and supporting astronauts’ health. Bacteria on the exchangers would impair their function and hamper the ISS’ ability to recycle its water supply. Currently, the station uses heat exchangers with coatings that slough off over time, contaminating the water.

• Surfaces for fuel delivery in space: With NASA EPSCoR funding, Husker researchers are working to develop surfaces aimed at helping rocket engines refuel efficiently under zero gravity conditions. Because liquid propellant behaves differently in space, NASA needs a reliable means of transferring propellant from a fuel storage tank to a spacecraft through a liquid acquisition device, or LAD, inside the tank, which then moves propellant to the spacecraft’s propulsion system. To maximize efficiency, Zuhlke’s team is modifying LADs with surfaces that strategically attract and repel fuel in certain areas.

• Water-repellant surfaces for power lines: Husker researchers are developing water-repelling surfaces that prevent power line cables from freezing and colliding, which leads to power outages.

• Surfaces that enhance heat transfer: Boiling water or other fluids is a crucial step in many industrial processes, from operating nuclear power plants to cooling electronic devices. Husker researchers are using FLSP to develop tailored surfaces that would improve the boiling process, which reduces energy consumption and improves a device’s function and longevity.

• Drag-reducing surfaces: Nebraska researchers are creating surfaces with super-hydrophobic properties aimed at reducing drag, which could be used to develop submersibles that travel farther underwater using less power. This could have important defense applications.

• Surfaces for satellite components: The team is exploring how FLSP-engineered surfaces might enhance satellites, making them more robust in the dynamic and thermal environments of launch and orbit.

Husker students are on the frontlines of this research. About 25 graduate and undergraduate students are affiliated with the center, and they collaborate across disciplinary lines.

“They’re really well-rounded for finding positions in industry or national labs after graduation,” Zuhlke said.

He and Gogos credit the university’s top-notch facilities — particularly the Nano-Engineering Research Core Facility and the Nebraska Center for Materials and Nanoscience — as well as multiple grants from the Defense University Research Instrumentation Program for enabling the team’s research.