Matthieu Rupin (Institut Langevin, Paris). Elastic metamaterials: from seismology to bio-physics.

The physics of waves has regained a lot of interest within the last two decades with the advent of metamaterials. The latter refer to man-made composite media engineered at a microscopic scale with respect to the wavelength. Whatever the type of waves the same approach is conducted: the response of the sub-wavelength elementary units give rise to macroscopic effective properties for the propagation of waves. In this talk, I will present two different kinds of metamaterials related to very different applications: seismology and bio-physics.

First, I will show experimental and theoretical results on a metamaterial dedicated to elastic waves with seismic applications as objective. The experiment is conducted on a thin table-size aluminum plate coupled to an ensemble of long aluminum rods acting as sub-wavelength resonators. This system is very instructive because of the presence of different types of waves in both the plate and the rods.

Second, I will present an example in the audible acoustic range of a metamaterial that exhibits a spatial non-uniformity of its properties which mimics the behavior of a dead cochlea. When active processes are introduced in the resonators we demonstrate the possibility to exploit non-linearities to reproduce some known features of the living cochlea.