Plenary speakers

Curriculum Vitæ:

Corentin Coulais is Associate Professor at the University of Physics of the University of Amsterdam, Coulais's Machine Materials group investigates designer soft materials, with a particular emphasis on how mechanical metamaterials can be programmed to achieve advanced mechanical tasks. Coulais explores the structure-property relationship in metamaterials with highly non-linear degrees of freedom by combining additive manufacturing, precision-desktop experiments, numerical methods and theory inspired from condensed matter. Recent highlights include shape-changing (2016), non-reciprocal topology (2017), self-folding (2018), and multi-functional (2021) metamaterials. He has recently pioneered active metamaterials, which combine the notions of emergence and symmetries inherent to condensed matter with the capabilities of robotics. This has led to experimental observations of non-Hermetian wave phenomena such as unidirectional amplification (2019), non-Hermetian topology (2020) and odd elasticity (2021). Coulais has received the NWO VENI (2015) ERC Starting (2019) and leads multiple collaborations with industry in the high-tech and food sectors. More information on his research activities can be found at coulaislab.com. 

 Abstract:

To analyze and design the vibro-acoustic performance of metamaterials, periodic structure theory is mostly used. Where possible, of course analytical models should be applied, but more and more geometrically complex designs are encountered in literature. In that case often the finite element (FE) method is used to model a unit cell, and by applying the Bloch theorem, dispersion curves can be computed. Stop bands are predicted as frequency ranges without free wave propagation (inverse approach) or as frequency zones with pronounced wave attenuation (direct approach). However, although the predicted stop bands are representative for the frequency range of noise and vibration attenuation, the accurate and efficient vibro-acoustic performance prediction of photorealistic metamaterials, also accounting for their finiteness and real boundary conditions requires more advanced modelling. In this presentation an overview of numerical metamaterial modelling techniques will be presented together with recent developments to speed up calculations. All routines presented start from FE unit cell models. Since FE unit cell models of complex metamaterial structures can become large, model order reduction (MOR) methods to accelerate dispersion curve computations have been developed and have recently been extended to towards vibro-acoustic unit cell models. In order to predict the sound transmission loss (STL) and sound absorption performance of infinite periodic structures with complex multi-physical unit cell designs, a fully coupled hybrid wave-based FE method has been introduced and MOR methods for fast STL predictions have been proposed. To account for finite counterparts sub-structuring and wave-based MOR approaches have been proposed for fast finite periodic structure forced response computations starting from FE unit cell models and finally to tailor the metamaterial design in view of achieving desired vibro-acoustic performance, optimization approaches which leverage the aforementioned advanced modeling strategies will be presented.

Curriculum Vitæ:

Elke Deckers received her MSc degree in Mechanical Engineering from KU Leuven in June 2008. During her PhD studies at the same university, she developed an alternative prediction method for mid-frequency vibro-acoustic analysis including poro-elastic materials. She received her PhD in December 2012 with a thesis entitled “A wave based approach for steady-state Biot models of poroelastic materials”. Holding a postdoctoral research grant of the Research Foundation – Flanders (FWO), she extended her research field to the numerical and analytical modelling of complex lightweight material systems, including viscous materials, metamaterials and meta-porous systems, and the development of supporting fast numerical prediction techniques. She did a research stay at Cambridge University. She was appointed Assistant Professor at KU Leuven Campus Diepenbeek in 2019, where she is currently broadening her domain of expertise to include also the production of lightweight material systems by polymer processing techniques like injection moulding and thermoforming. This way, she aims to close and exploit the full (digital) loop ranging from design, over manufacturing to the actual performance of the product.

Title: Introduction to topological acoustics and examples with one-dimensional sound

 Abstract:

Curriculum Vitæ:

Romain Fleury is an assistant professor at EPFL. He received the M.S. degree in micro and nanotechnology from the University of Lille, Lille, France, in 2010, and the Ph.D. degree in electrical and computer engineering from the University of Texas at Austin, Austin, TX, USA, in 2015. In 2016, he was a Marie-Curie Post-Doctoral Fellow at ESPCI Paris-Tech, and the CNRS Langevin Institute, Paris, France. His research interests include a wide variety of topics in the field of wave physics and engineering, including periodic structures, active and time-modulated metamaterials, nonreciprocal wave propagation, classical topological insulators, and nonlinear effects.

Title: Engineering holographic metasurfaces for biomedical ultrasound applications

Abstract:

Optical holograms can modulate light wavefronts to generate visible images. In the same way, acoustic images can also be synthesized by holograms, shaping the areas where mechanical waves present a high amplitude, and areas where the media is at rest. In this work, we present the recent advances of acoustic holograms and structured media to engineer the acoustic wavefront to focus ultrasound beams for biomedical applications. We show how we can engineer ultrasonic wavefronts by using acoustic metasurfaces. This results in complex holographic lenses, or acoustic holograms, that can shape therapeutical acoustic images for the non-invasive treatment of neurological disorders, to produce cavitation patterns for localized drug delivery, and thermal patterns of arbitrary shape for targeted hyperthermia. In this way, acoustic holograms emerge as a disruptive and low-cost approach for biomedical ultrasound applications in neurology, including blood-brain barrier opening for localized drug-delivery or neuromodulation using low-cost systems. In addition, increasing the temperature using low-cost and MRI-compatible holographic transducers might be of great interest for many biomedical applications, such as ultrasound hyperthermia, physiotherapy, or high intensity focused ultrasound, where the control of specific thermal patterns is needed.

Curriculum Vitæ:

Noé Jiménez, Ph.D. in Acoustics from the Universitat Politècnica de València, (Spain) in 2015. Noé Jiménez is currently “Ramón y Cajal” Fellow (tenured) at Spanish Research Council. In 2015 he joined the CNRS (UMR6613, France) for a post-doctoral position to research on acoustic metamaterials and in 2017 he joined the Institute of Instrumentation for Molecular Imaging as a “Juan de la Cierva” post-doctoral fellow to research on ultrasonic metamaterials for biomedical applications. He has been visiting researcher at Columbia University (NY, USA) and at the University of Salford (Manchester, UK). He was awarded by the Spanish Royal Society of Physics in 2019 for his scientific contribution to transcranial ultrasound propagation using acoustic holograms. He is the author of 5 patents in the field of biomedical applications of ultrasound, published 44 journal papers, edited 2 complete books, and 7 book chapters, and participated in more than 200 conferences. He teaches at the Applied Physics department of the Universitat Politècnica de València. His research interests concern from fundamental research in mechanical waves in complex and artificially structured media such as metamaterials, to its application for innovative biomedical ultrasound techniques.

Curriculum Vitæ:

Gaëlle POIGNAND is an engineer at LAUM. She has completed a master's degree in Acoustics  (2002) at the Université de Poitiers and received her PhD (2006) from the Université du Maine where she investigated theoretically and experimentally the behaviour of a compact thermoacoustic refrigerator with four sources. In particular, fluid flow velocity measurements were carried out with two optical methods: Laser Doppler Velocimetry  and Particle Image Velocimetry. She completed a post-doctoral fellowship at the Energy Center of Netherlands under the mentorship of Dr. H. Tijani. For two years, she gained experience with thermoacoustic engine prototypes working with helium under pressure and with the computer code DeltaEC dedicated to the estimation of thermoacoustic device performance. She then completed a second two-years post-doctoral fellowship in thermoacoustic at the LMFA. During which time, she notably studied aerodynamic and thermal fields behind a stack using respectively Time-Resolved PIV and Cold Wire Anemometry. In 2010, she joined the LAUM. Her current work deals with the design and characterization of thermoacoustic machines on the one hand and on the control of wave propagation behaviour using the thermoacoustic effect on the other.r