Plasma makes up 99% of the matter in the universe, including stars and the sun. On earth, plasma shows itself in beautiful patterns in the sky – aurora borealis and lightning. You also look at it when you see neon lights, plasma balls, plasma TVs, some car headlights and more. Also known as the fourth state of matter, plasma is playing a key role in an increasing number of scientific areas from materials to healthcare.
Plasma is the result of some ingredients and a reaction on the atomic level: Plasma can be produced in the lab by heating a gas to an extremely high temperature. This causes such hard collisions between its atoms and molecules that electrons are ripped free, providing the electrons and ions needed to make plasma.
Depending on the gas used, different colours of plasma can be produced. Argon gas is the gas used to create the famous plasma with a beautiful purple glow.
While plasma happens naturally in space and mostly has to be man-made on earth, it is actually easier to maintain on earth. Due to the controlled conditions, there are less collisions between the atoms, which makes it easier to maintain the ‘artificial’ plasma than it is for ‘natural’ plasma in space.
Plasma has increasing uses in science. Aside from a wide range of uses in material sciences, it has shown promising applications for cancer treatment, skin treatment and wound disinfection. It can also be used as vector to coat molecules on different surfaces to improve and/or modify properties, even dental implants where it improves biocompatibility and has an antibacterial effect.
Scientists for example use to etch lines in the surface of solar cells, as it makes it possible to draw lines only a few nanometres wide as well as to deposit material of a few nm thick. It is commonly used by all semi-conductor manufacturers for chips and microprocessor production, found in every smartphone, car, computer and more.
Making underwater valves more durable; antibacterial coatings for better dental implants; gold nanoparticles for 3d manufacturing; coatings to make lenses self-cleaning; super black coatings for space research; hydrophobic coatings – these are just examples of the many areas where researchers in Luxembourg are putting plasma to use!
Physical vapour deposition – coating materials using plasma
How do scientists coat materials using plasma? Using a technique called physical vapour deposition, they place the material to be coated inside a dedicated machine, some of which have been designed in Luxembourg, at the Plasma and Process Engineering Group at LIST.
“We take the ions of the plasma – usually nitrogen or argon gas – and they splinter the matter and deposit it on the material to be covered. It is mainly used for hard coatings, making them resistant to oxidation at high temperature.”
Explains physicist Simon Bulou, who has been a researcher in the group for a number of years.
Plasma robot helps coat dental implants
Physicists, chemists and engineers working with plasma don’t just use plasma to coat things – making the machines used in all these efforts better is also a big part of their work. Some for research, some for making industry processes more efficient. The scientists in the Plasma Process Engineering Group have built, or improved, a large part of the machines in the lab.
One of them is a robot arm with a plasma torch – the Plasma Robot. It makes it possible to coat complex objects with a lot of detail – such as dental implants, screws inserted into the bone structure. The researchers are for example using the Plasma Robot to give the dental implants with an antibacterial coating, with the aim of improve the dental bone structure and avoid any rejection of the implant.
Liquid gold nanoparticles for safer 3D manufacturing
Nanoparticles play an important role in 3D printing, but they’re not exactly healthy to be around and are normally made with powder. LIST researcher Simon Bulou has made his own atmospheric plasma torch for a project creating and immobilize it on surfaces directly from a liquid solution.
The aim is to produce nanoparticles of gold and titanium for additive manufacturing, the “trendy stuff” as researcher Simon points out – additive manufacturing is also known as 3D printing, the construction of a three-dimensional object from a digital 3D model.
Gold nanoparticles have shown huge potential in many areas such as improving drug delivery in our system, making solar cells better, water decontamination and more. Their potential has been limited by the being impractical and not-so-safe to use – creating them and implementing them directly on the final product remove these barriers.
Repel and collect for better 5G
Another coating produced in the lab creates a layer that is both extremely water repellent – and water-gathering. Hard to imagine? Take a look below!
The lab is working on a project with a direct application: 5G antennas have microwaves, and they absorb water, which is bad for the signal quality. Thanks to this coating, this will no longer be an issue!
About the Plasma Process Engineering Group
The Plasma Process Engineering group at LIST, headed by Patrick Choquet, develops fundamental and technological expertise in the area of process engineering for advanced surfaces coatings. The group focuses on its recognized expertise in Research and Development of both thermal and plasma surface modification for the synthesis of functional polymer thin films, functional inorganic coatings, or functional/smart surfaces. The FNR has supported many of their research projects over the years. The team has around 10 – 15 running research projects at all times, many of them made possible by FNR funding.
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