This is a piece of skin. Of artificial skin. And now, OK, I’m just going to paste it on this hand, and I'll greet you all.
(Laughter)
I will show you how it works. So please have a look at what happens on the table, where there is one piece of this artificial skin, and also what happens on the screen of the laptop that you see in the video that is about to start.
So this is me. I'm first breathing on the skin. And you see now that this line that first was flat now shows a bump. And now I'm touching it with my finger. And again, another bump. I am touching it one more time with the back of a feather. And now tinier bumps are coming. And again. Now even smaller bumps are coming.
But what is this line? This, what we are looking at, is electrical current, which first is constant. And then when we touch the skin or breathe on it or touch it with a very light feather, it shows a signal. So this bump that you see is a signal in the electrical current. And this is actually exactly how our skin also works. So we have receptors in the skin which sense what is happening on the skin. And then they produce an electrical signal which travels through the nerves and arrives at our brain where it is recognized.
I am a chemist by education, and I worked in the field of material science, which is a very interdisciplinary field, since almost 20 years now. First, as a PhD student in Italy, in Bari, and then at MIT as a postdoc, and now I am group leader in Graz. And it is almost six years that we are working on artificial skins. Almost 12 students, between master and doctoral students, have worked on these devices, trying to study how the materials work, how they work together and how to build this device.
And after this, we have for the first time produced an artificial skin that can respond at the same time to three stimuli. Touch, so force, temperature and humidity. And it can do this also at an unprecedented resolution. So it's a very tiny device. You will see how it is done. And so this means that it can sense objects that are actually smaller than the objects that can be sensed with our skin. Our skin has a resolution of one millimeter square. This skin has a resolution of 0.25 millimeter square. So I promised I would give you some technical details. I know you are really looking forward to them.
(Laughter)
The main component of this material, of this skin, is what is called the stimuli-responsive material. So what does it mean that it is stimuli-responsive? It means that at the beginning it is small. And when we have either humidity or light or pH or temperature changes, this material changes in its shape, and it becomes bigger. It can arrive to even doubling or tripling its thickness, its original thickness. And this is an amazing property, but it happens at a very, very microscopic scale because we produce these materials as thin films, so sometimes even one million times smaller than a millimeter.
So the problem was, OK, how do we translate this very big change in thickness into something measurable? And we thought, OK, let's combine it with a piezoelectric material. Now maybe this word sounds a bit complex. Sounds like something you have never seen in your life, never heard before, but it's not really true. You have been in contact with this material many times. I am in contact with it right now. It's in microphones, for example. So it's the material that when there is a movement, produces electricity. And so in microphones there are membranes that when they move, produce electricity. It's also the material that is in these funny greeting cards that when you open, they make this music. The music is also made with the piezo material. So there is an electrical circuit into the card and when you open it, it moves a membrane and the membrane makes the music. And it's also the material that is included in the arm wristbands, those that measure the heartbeat.
OK. So we combined these two materials in these cylinders that you see in the picture. So in the middle we have that material I showed you before, the stimuli-responsive material, the material that changes its thickness and gets bigger. And on the outer shell we have the piezoelectric material, the material that when the inside gets bigger, the outside produces the electricity. And this is how it is done. Easy-peasy.
(Laughter)
Then these type of cylinders are very tiny, and we have several of them in this device so that we can sense with very high resolution the three different types of stimuli I was telling you before. And a bit more of technical details. I know they are exciting, right? So how do we do these cylinders? We do them using a template, the one that you see in the picture on the top. This is a template with a lot of wells, so a lot of holes. And then we refill the holes. First we fill them up with the piezoelectric material, which is represented in yellow in the bottom figure, and then we fill it up with the stimuli-responsive material that is the light blue in the bottom figure. But to do this we cannot use liquids, because as you know, liquids would fill the wells from the bottom up. And instead we want to cover also the lateral walls. And so we do this using vapor deposition. So the whole process of production of these things happens in vacuum chambers like the one that you can see in the picture.
And you may be wondering, OK, why working on this topic? Why working on artificial skin? So from a material scientist point of view, the skin is really a complex ensemble of materials and functions. Skin is useful for protection, secretion, adsorption, heat regulation and sensing. And so being able to just reproduce artificially all these properties -- or actually, for the moment, only the sensation -- looked like a challenge. And so I was happy to embrace it.
OK, now I'm done with the technical details. Now I know you are all wondering, OK, you have done these artificial skins. But why?
(Laughter)
I will show you some fields of application, ending with the one that I think could be the closest. So we have also seen how there are many victims of burns. These burns can be so huge that they even take away the receptors in the skin. And so people would then lose the sensation where there was this burn. Now imagine a future where actually victims of burns could, thanks to our technologies, regain the sensation.
216 million users of smartwatches in 2022. Should I ask how many of you have a smartwatch now? Wearing a smartwatch? Yeah, so imagine you are, for example, running on a hot day, and your smartwatch could measure, for example, the level of hydration of your skin and warn you maybe if you are reaching the limit of the hydration.
Another interesting field of application would be robotics. Nowadays, humanoid robots are used in many fields, for example in medicine but also in household. And these robots are exposed to several stimuli, several interactions with the environment and with the humans, and sometimes they have too many inputs at the same time. And this is the reason number one for robot failure. So imagine a future where actually a robot could be a bit more sensitive, a bit smarter. This would lead also to a higher safety of this technology.
And finally, unfortunately, a very highly cited paper projects the number of people in need of a prosthesis on the rise, from 1.6 million in 2005 to 3.6 million 2015. So a lot of people are born without limbs, and some people lose them during their life due to, for example, vascular diseases. This is so common that you may even know somebody who actually is in a need of prosthesis. Now imagine we could coat the prosthesis with this artificial skin and give this type of people the sensation back.
With almost a decade of working in this field, I'm hopeful that technologies like this could help in the future not only regain, but also maybe augment capabilities.
Thank you.
(Applause)
