Emmanuel Defay, materials researcher at LIST, and his colleagues are researching the use of piezoelectricity, which could potentially revolutionise how we use our tablets and phones.

In everyday language we distinguish between five senses. We can hear, smell, taste, see, and feel. Modern phones are already catering to two of these senses.

At the beginning, we were able to hear someone speak to us, and then, following the development of smartphones, we could also see the other person. Researchers at the Luxembourg Institute for Science and Technology (LIST) are already working on the third phase: being able to feel. One of those researchers is Emmanuel Defay. The materials researcher has specialised in the area of piezoelectric materials.

Emmanuel, what are piezoelectrical materials?

Piezoelectrical materials are isolators which prevent a current flow. The electric charge can for instance not flow through isolators made out of glass, rubber, or plastic. In the case of piezoelectrical materials however, the electricity can selectively alter the form of the isolator.

In the LIST department for material research, we are specialised in this field on thin films in the micrometre range which could for example be built into smartphones or smartwatches.

Normally silicon is used as a carrier in this context. However, we are among other things looking into applying piezoelectrical materials with glass. This glass could then be built into buildings or cars, or, as mentioned before, into smartphones.

What sort of practical uses are there for applying this sort of material on the surface of a smartphone?

We are currently working with the start-up company Hap2U from France, and they already have a technical use for it. However, this does not yet involve the ultra-thin films, but small areas of about one square centimetre and a thickness of one millimetre to start with. These are installed on the display of a smartphone. The idea behind these piezoelectrical films, or rather flat blocks, is to transfer vibrations onto the glass.

The transfer of vibrations in smartphones is not unheard of…

Yes, that is true. Smartphones can vibrate, and you can also feel this with your hand. However, what is not possible is a nuanced and delicate perception with the fingers. You only feel the vibration, but nothing more. With this new technology, which transfers acoustic waves at a much higher frequency, you can achieve a diverse and very subtle variety of vibrations.

This allows us to simulate the texture of objects on our displays using vibrations. When we see for instance a stone on our display, we can run our finger across it and it feels like a stone. In the same way, you could also feel the composition of different textiles through the display.

So, if in the future I wanted to order a pair of trousers or a t-shirt online, I could feel beforehand whether the fabric feels nice or not?

Exactly. This is one possible area of use. The company we are working with has developed a very vivid demonstration model in order to showcase the possibilities. They have fitted a tablet with the technology. On the display, you can see a fish with scales.

Depending on which direction the user is running over the scales of the fish, it either feels smooth, or they can feel a slight resistance with each scale. In combination with the image of the fish, it appears as if the user can actually feel the scale structure.

This technology is also the only one which offers a sort of “button solution”. This makes it possible to feel a “click” when pressing the glass surface.

Piezoelectrical materials must therefore be as transparent as possible?

This is precisely the challenge. In most cases, isolators are transparent anyways. What we need are electrodes which are also as transparent as possible. This is another project of the department of materials sciences. We are currently researching how to fit both of those together. This sort of transparency is not necessary for all piezoelectrical applications on glass, but it is in our specific case.

What do you think: When will our smartphones and tablets make us with this technology?

This is difficult to say. However, a lot of work is being done on this in a lot of fields. On the so-called Technology Readiness Level (TRL), which defines the state of development of a new technology on a scale of one to nine, we are approximately on level four at the moment, according to my assessment. This means that we are on a level on which the industry is already involved as well as testing and refining applications.

Interview: Uwe Hentschel