Watch music transformed into sonic sculptures in this cool video: CYMATICS – Science Vs. Music – Nigel Stanford

A team at the University of Rochester has created a new laser etching technique that makes metal surfaces amazingly water repellent:

Laser-generated surface structures create
extremely water-repellent metals

Scientists at the University of Rochester have used lasers to transform metals into extremely water repellent, or super-hydrophobic, materials without the need for temporary coatings.

Super-hydrophobic materials are desirable for a number of applications such as rust prevention, anti-icing, or even in sanitation uses. However, as Rochester’s Chunlei Guo explains, most current hydrophobic materials rely on chemical coatings.

In a paper published today in the Journal of Applied Physics, Guo and his colleague at the University’s Institute of Optics, Anatoliy Vorobyev, describe a powerful and precise laser-patterning technique that creates an intricate pattern of micro- and nanoscale structures to give the metals their new properties. This work builds on earlier research by the team in which they used a similar laser-patterning technique that turned metals black. Guo states that using this technique they can create multifunctional surfaces that are not only super-hydrophobic but also highly-absorbent optically.

Guo adds that one of the big advantages of his team’s process is that “the structures created by our laser on the metals are intrinsically part of the material surface.” That means they won’t rub off. And it is these patterns that make the metals repel water.

“The material is so strongly water-repellent, the water actually gets bounced off. Then it lands on the surface again, gets bounced off again, and then it will just roll off from the surface,” said Guo, professor of optics in the University’s Hajim School of Engineering and Applied Sciences. That whole process takes less than a second.

The materials Guo has created are much more slippery than Teflon—a common hydrophobic material that often coats nonstick frying pans. Unlike Guo’s laser-treated metals, the Teflon kitchen tools are not super-hydrophobic. The difference is that to make water to roll-off a Teflon coated material, you need to tilt the surface to nearly a 70-degree angle before the water begins to slide off. You can make water roll off Guo’s metals by tilting them less than five degrees.

As the water bounces off the super-hydrophobic surfaces, it also collects dust particles and takes them along for the ride. To test this self-cleaning property, Guo and his team took ordinary dust from a vacuum cleaner and dumped it onto the treated surface. Roughly half of the dust particles were removed with just three drops of water. It took only a dozen drops to leave the surface spotless. Better yet, it remains completely dry.

Guo is excited by potential applications of super-hydrophobic materials in developing countries. It is this potential that has piqued the interest of the Bill and Melinda Gates Foundation, which has supported the work.

“In these regions, collecting rain water is vital and using super-hydrophobic materials could increase the efficiency without the need to use large funnels with high-pitched angles to prevent water from sticking to the surface,” says Guo. “A second application could be creating latrines that are cleaner and healthier to use.”

Latrines are a challenge to keep clean in places with little water. By incorporating super-hydrophobic materials, a latrine could remain clean without the need for water flushing.

But challenges still remain to be addressed before these applications can become a reality, Guo states. It currently takes an hour to pattern a 1 inch by 1 inch metal sample, and scaling up this process would be necessary before it can be deployed in developing countries. The researchers are also looking into ways of applying the technique to other, non-metal materials.

Guo and Vorobyev use extremely powerful, but ultra-short, laser pulses to change the surface of the metals. A femtosecond laser pulse lasts on the order of a quadrillionth of a second but reaches a peak power equivalent to that of the entire power grid of North America during its short burst.

Guo is keen to stress that this same technique can give rise to multifunctional metals. Metals are naturally excellent reflectors of light. That’s why they appear to have a shiny luster. Turning them black can therefore make them very efficient at absorbing light. The combination of light-absorbing properties with making metals water repellent could lead to more efficient solar absorbers – solar absorbers that don’t rust and do not need much cleaning.

Guo’s team had previously blasted materials with the lasers and turned them hydrophilic, meaning they attract water. In fact, the materials were so hydrophilic that putting them in contact with a drop of water made water run “uphill.”

Guo’s team is now planning on focusing on increasing the speed of patterning the surfaces with the laser, as well as studying how to expand this technique to other materials such as semiconductors or dielectrics, opening up the possibility of water repellent electronics.

Funding was provided by the Bill & Melinda Gates Foundation and the United States Air Force Office of Scientific Research.

The article, “Multifunctional surfaces produced by femtosecond laser pulses,” was published in the Journal of Applied Physics on January 20, 2015 (DOI: 10.1063/1.4905616). It can be accessed at: http://scitation.aip.org/content/aip/journal/jap/117/3/10.1063/1.4905616

Professor Chunlei Guo has developed a technique that uses lasers to render materials hydrophobic, illustrated in this image of a water droplet bouncing off a treated sample. Photo by J. Adam Fenster / University of Rochester

I’ve posted several times about Elon Musk’s Hyperloop fast mass transit concept. Today he posted a couple of brief statements about plans to build a test track:

* Elon Musk on Twitter:

Will be building a Hyperloop test track for companies and student teams to test out their pods. Most likely in Texas.

* Elon Musk on Twitter:

Also thinking of having an annual student Hyperloop pod racer competition, like Formula SAE

See also:

• Elon Musk Hyperloop Test Track – Business Insider
• Elon Musk Boosts Hyperloop With Talk of Texas Test Track – NBC News.com

Update: Here is a transcript (courtesy Trent Waddington) of Elon’s remarks in Texas in which he briefly mentions the Hyperloop test track before switching to comments about Tesla.

Update 2: An article with more details about the test track : With a Hyperloop Test Track, Elon Musk Takes on the Critical Heavy Lifting -WIRED

If Musk does in fact build a test track, in Texas or elsewhere, it would be a huge help to the company that’s made more progress than anyone toward making the Hyperloop happen. The track isn’t the part of this endeavor that’s hard to engineer. “It’s a couple of tubes and a vacuum pump,” says Dirk Ahlborn, CEO of JumpStartFund, an El Segunda, California-based startup that is taking Musk up on his challenge to develop and build the Hyperloop. But, like most chunks of infrastructure, even in prototype sizes, it’s expensive.

An artist programs a robot to lay out pretty patterns on the beach :  Robot sand artist turns beach into giant canvas – New Scientist

This got me to thinking about the growing concern that as robots and AI systems become smarter and more mechanically capable, they will replace more and more people in a greater range of jobs. On the other hand, perhaps by using a robot assistant as this artist does, a person can accomplish much more than they would on their own. This in turn would greatly expand the types of products and services an individual or a small company can provide.

Automation reduces the labor needed to provide a particular product or service. Along with economies of scale and other factors, this has been key to increasing productivity and raising our standard of living. New types of products and services have always arisen to absorb the labor freed up as older industries became more automated.

There’s no reason this process cannot continue. For example, instead of an artist and a robot scraping sand, an entrepreneur and a fast-moving, intelligent robot mower could cut all the lawns in the neighborhood in a day at low-cost while doing enough lawns in total to make good money.

There is essentially an infinity of services and products that can be created and sold. Robots will allow many that were too expensive or impractical before to become affordable. Robots should be seen as partnering with people, not replacing them.