Active lines

Acoustic metamaterials and phononic crystals


Acoustic metamaterials are artificial structures that present new striking and exotic properties that are not present in conventional or natural materials. Using the concepts of strong dispersion and slow-sound, negative compresibility or negative mass density, these new materials can be designed to obtain interesting properties such as perfect sound absorption, zero-sound transmission, focusing or specific scattering patterns.

Singular acoustic beams

High Order Bessel Beam

Nondifracting acoustic beams can be generated under specific conditions. I'm interested in the generation of singular beams such as zero-th and higher order Bessel beams. These can be generated by using diffraction gratings in the same manner as Fresnel zone plate, and also by using acoustic metamaterials. Focusing of the beams is also considered and acoustic vortices can be easily generated by passive devices. Furthermore, nondifracting nonlinear beams have been also obtained by using periodic materials under self-collimation regime.

Intense waves for biomedical ultrasound applications

Currently I'm studying the acoustic field and acoustic radiation forces generated by high intensity focused ultrasound. The amplitude-dependent beam properties can be determined by means of non-paraxial simulation methods. In this way, high intensity focused ultrasound fields are characterized in the focal area by the appareance of nonlinear acoustic effects such as harmonic generation and self-(de)focusing. Applications, in the weakly nonlinear regime, include the characterization of the acoustic field for ultrasound-induced Blood-Brain Barrier opening, a emerging technique for localized, transient, noninvasive and safe targeted drug delivery in the brain. In the highly nonlinear regime applications include the use of High Intensity Focused Ultrasound for thermal ablation and hypertermia applications.

Nonlinearity in periodic media

The dynamics of the acoustic waves travelling through periodic structures show very special properties, e.g. anisotropic dispersion. In addition, when intense waves are considered, the interaction of nonlinear waves with the material dispersion lead to the emergence of a wide range of intrinsically nonlinear phenomena. I'm working in the existence of nonlinear localized waves in different media: supersonic excitations in cation lattices, solitons and nonlinear waves in layered acoustic media, sonic crystals and macroscopic lattices of oscillators.

Computational methods for finite amplitude acoustic and elastic waves in complex media

fdtd cell

I'm designing simulation techniques for acoustic fields in complex media. These computational methods include nonlinear acoustic propagation, arbitrary frequency dependent attenuation and dispersion for modelling biological media, as well as elastic waves in complex solid media. These time domain algorithms include arbitrary boundary conditions and media heterogeneity, and can be applied for correctly describe the acoustic wave processes in biological media for medical ultrasound applications. On the other hand, I designed computational techniques for describe finite amplitude propagation through lattices and periodic media.

Microbubble shell dynamics

I'm studying the sheel dynamics of acoustically driven microbubbles, looking for the existence of Intrinsic Localized Modes (ILM) in macroscopic-discrete models of ultrasound contrast agents for drug and gene administration.

Past projects

Ultrasound techniques for vegetable tissue characterization

The elastic parameters of fruit and vegetables are normally monitored in quality control processes as there is a good correlation to the degrees of firmness, turgidity and humidity. These parameters have been traditionally measured by means of penetration tests, which are destructive. We have designed, tested and validated nondestructive ultrasound techniques for elastic and acoustic characterization of orange fruits, providing a quality monitorization method for postharvest processes.