Neomi Lewis ‘21

While water-repellent surfaces already exist, these surfaces usually gain this property by modifications including coatings, paints or solvents. A team of physicists at the University of Rochester is attempting to change the surface of metals with high power lasers to create super water-repellent surfaces without the use of traditional coating methods.

It is an ambitious project that is expected to last six years with an estimated budget of $10 million. There is much commercial interest in this undertaking as the applications are wide-ranging; they include de-icing large vehicles, and rust and corrosion prevention of exposed metals, to cleaner, anti-microbial surfaces for surgical and medical facilities.

First, the laser technology must be made much more powerful for it to be used for these purposes. The lead researcher, Dr. Marciante, stated: “What they [FemtoRoc] need is a high-powered, ultra-fast, femtosecond-class laser system with average power measured in kilowatts, rather than the 10s of watts now commercially available.”

The existing super-hydrophobic technology uses lasers to alter metal surfaces in a way that creates patterns of both micro-scale and nano-scale structures effectively giving the metal new physical properties. The team has also been able to use this technique to create surfaces that attract different surfaces. In addition, Dr. Chunlei Guo, a professor of optics at the same institute has developed a process that treats metal surfaces to absorb virtually all wavelengths of ambient light.

The setback, however, is that Guo’s laboratory takes approximately one hour to pattern a 1-inch-by-1-inch metal sample. This means the process is not yet commercially viable and the lasers need to have increased power.

Addressing this need has yielded two main problems. The first is that in scaling up power while still trying to maintain a short pulse, a lot of power spreads out or does not focus as desired. The beam tends to broaden or become modulated (different modes form). Secondly, the high power heats up the fiber too much.

Marciante already has some ideas in store for tackling these issues. For example, he suggests, “in principle, if you cut fiber length in half, you can reach up to twice as much energy. The tradeoff is, however, you’re also dumping the heat into half as much space.” If he is successful in developing the desired technology, there will be a great number of applications it could possibly change.

References

1. A laser focus on super water-repellent metals. Phys.org, (2018).
2. Image retrieved from: https://commons.wikimedia.org/wiki/File:Lasertests.jpg