Materials can be given special characteristics through the use of plasma. Simon Bulou, researcher at the Luxembourg Institute of Science and Technology (LIST), explains the range of possibilities.
Simon, you are doing research with plasma. What exactly does this mean?
Plasma is the fourth state of matter after solid, liquid, and gas. If you expose gas to a sufficiently high energy source, some electrons will dissolve out of their atom. We are then left with positively charged nuclei – so-called ions – and negatively charged, freely moving electrons. Plasma is therefore also a gas but consists of neutral gas molecules and charged particles.
We are using these charged particles to trigger chemical or physical reactions, or to produce new materials with new characteristics. In a sense, plasma is similar to a flame or a lightning bolt but with less energy.
How is the plasma being used?
I have been working at LIST for 8 years, in the Plasma Process Engineering Group of the department of material sciences, where we are working on the development of plasma processes. Our team is researching the treatment of materials in particular.
At the moment we are using natural peptides (an organic chemical compound which is created by connecting several amino acids) of plants and animals and are connecting them through the use of plasma with the material surfaces in order to give them special characteristics.
And what are these characteristics?
This differs significantly. We are developing materials with special and unique characteristics, e.g. by fitting a cutting tool with a very thin layer of a very hard material. We are also researching photocatalytic coatings which are capable of cleaning themselves when exposed to sunlight.
We are also working on so-called antifouling materials, i.e. coatings which ensure that biofilms (mucus layers) or dirt cannot build up. Another research project involves non-poisonous, super-hydrophobic coatings which can make a material completely water-repellent – also known as the lotus effect.
So, there are countless potential applications…
Exactly. And this is what makes this so interesting for industrial use. We are regularly working together with companies such as Goodyear for instance. Inside of rubber wheels are galvanised steel wires. Zinc has a very weak adhesion on rubber. For this reason, the wires are coated with a copper layer, which has a very good adhesion on rubber.
One of our tasks was to find a replacement for the precious copper without changing the adhesive properties. Thanks to the method which we developed, we were able to coat the wires through the use of plasma with a material which not only matched the performance of copper-rubber, but actually exceeded it.
Another project involved treating dental implant screws with plasma. This treatment allows for the sedimentation of a material which blocks the development of bacteria and boosts the growth of bone cells as well as the correct implantation in the jaw.
Through the use of plasma, we are able to make materials antibacterial, corrosion-resistant, or self-adhesive – whichever is preferred.
And how are you using plasma to treat the material?
There are different methods ranging from application in a high vacuum environment to atmospheric pressure. Together with Molecular Plasma Group (MPG) – a Luxembourgish start-up which came out of LIST – we are developing different atmospheric plasma processes which can then immediately be taken up in an existing industrial production line.
Our group is using among other things a so-called plasma burner. This is a device which generates a plasma flame measuring a few centimetres, which we then use to treat the material surfaces.
This plasma device is especially suited for industrial use. The plasma burner can also be combined with an industrial robot which enables the treatment of 3D workpieces. Such a plasma robot can therefore be used in many different ways and can be adapted entirely to customer needs.
Interview: Uwe Hentschel
Photo: Uwe Hentschel