Every day the media report new performances that robots can acquire. They can walk, run, climb, play. But they have no sense of touch and are devoid of any sensitivity. Swiss researchers have invented an elastic, multi-material, electrode-clad super-fibre that perfectly fulfils the functions of a nerve.
Dhe engineers of the Swiss Federal Institute of Technology in Lausanne (EPFL), in association with teams from the University of Berlin, under the leadership of Professor Fabien Sorin, have recently published in the journal Advanced Materials the results of their discovery: cables capable of sending electronic signals in response to touch that could perform the functions of a nerve for robots.
Basically, this "nerve" takes the form of a tiny elastomer fibre incorporating various materials such as electrodes or nano-composite polymers. This fibre is able to feel very precisely every pressure and distortion exerted on it, and can deform by up to 500 %, before returning to its original size.
In order to build this "nerve", the team first assembled a macroscopic version of the fibre, with materials organized in a well-defined three-dimensional pattern. This preform is then heated and stretched like molten plastic until it forms fibres a few hundred microns in diameter.
On the inside, the patterns lengthen along the axis of the fibre, but shrink in the transverse direction. Their relative positioning does not change, resulting in a fibre with a highly complex microarchitecture.
Until now, only rigid fibres could be produced using this method, but scientists have used a type of thermoplastic elastomer that has a high viscosity when heated. Once the fibre is finished, these fibres can be stretched and deformed, and they always return to their original state.
In a second step, engineers introduced, inside the fibre, rigid materials such as nano-composite polymers, metals, thermoplastics, but also liquid metals that can be easily deformed. « For example, we can place three electrode channels at the top of the fiber and one at the bottom. Depending on the direction the pressure comes from, different electrodes will make contact, sending a specific signal. "Fabien Sorin explains in a statement.
This technique makes it possible to know the type of deformation undergone by the fibre, distinguishing compression from shear, for example. Together with their colleagues in Berlin, the Swiss researchers have integrated their fibres into robotic fingers as artificial nerves. With each "touch", the deformed fibre sends indications about the interaction between the robot and its tactile environment.
Until now, other techniques developed in the field of robotic touch engineering have been more voluminous or rely on bulky fluid transport systems. The invention of the EPFL engineers is interesting because their cable is very thin, extensible and can be easily produced in large quantities. Indeed, the team behind this discovery claims to be able to produce several hundred metres of fibre in a short period of time, a bit like optical fibres.
The opportunities for robotics are immense, but the Swiss team is also thinking of adapting its technology to weave intelligent garments that would react by "feeling" their wearers and could also react to their environment. They are also considering integrating tactile keyboards into clothing or developing sensitive medical prostheses. While waiting for these industrial opportunities, the team is filing a number of patents.
To be continued.
Sources: futurism, EurekAlert, ARCinfo
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