So bizarre in fact that metals and other materials can be altered to completely alter their properties, like making them resilient to water or bacteria. This is the cornerstone of new research looking into the hidden world of surfaces, with the potential to improve our everyday lives by creating dishwashers which clean themselves or longer-lasting batteries. An integral breakthrough that has allowed this to be possible is that the ultrashort pulse laser. Until 10 years back this technology was too expensive and unable to create high enough power to create some interesting effects which could be applied on a commercial scale. However, it’s now been developed to a point where researchers can use it to alter the structure of routine items. Electrons This tiny pulse duration is short enough that it may excite electrons onto the surface of a metal and change its properties before the power is converted to heat as the electrons’unwind’, or return to a steady state, between each pulse. ‘So what happens is you have lots of very excited electrons which travel around the area, and then they all relax, and that is converted into heat in one hit,’ said Dr Adrian Lutey, a mechanical engineer and research fellow in the University of Parma in Italy who works on a project named TresClean. ‘And you can provoke some quite interesting modifications in this way.’ TresClean is considering ways that ultrashort pulse lasers may enhance numerous businesses, particularly the food sector and white products — such as washing and washing machines — and exploring the constraints of what may be possible. The group is exploring how metal surfaces can be made resistant to water utilizing lasers, including one of the world’s most powerful ultrashort pulse lasers in the University of Stuttgart in Germany, with an ordinary energy of one kilowatt. This rough surface has an identical effect on a lotus leaf, which has a surface chemistry that prevents water from sticking. Anti-bacterial Utilizing this technique, it is possible to create liquid-repellent anti-bacterial surfaces. Bacteria thrive in water, so pipes and other equipment has to be cleaned frequently to avoid any type of build-up — a procedure which takes both substantial time and money. But if the surface never grew bacteria in the first place, this dilemma could be eradicated. ‘A analog is a bed of nails, the bacterial cells don’t have not anywhere they could attach to,’ said Dr Lutey. ‘Utilizing laser texturing to produce an anti-bacterial response is cutting edge.’ So far the results have been promising, with the staff publishing a number of research papers on how successful the technique can be. They hope this could have quite a few programs, such as in the food packaging industry, in which milk and other liquid foods have been transported by machines. This must be cleaned every couple of hours using powerful cleaning solutions. ‘If we can lower the total amount of cleaning required, we can decrease downtime and we could reduce any risk of contamination where cleaning goods end up in the food,’ said Dr Lutey. Likewise in dishwashers and washing machines, this can stop a biofilm — a bunch of bacteria — forming inside the machine, which can cause a dishwasher tank to smell as bacteria float round. Together with laser-treated surfaces, these products may work with less water and get less cluttered. Laser techniques can be applied elsewhere. By way of example, ships have a common problem working with a biofilm’slime’ in their hulls where germs have grown. But if the hull of this ship could be made resistant to water, then the germs wouldn’t have anywhere to catch.
September 19, 2020
June 8, 2020