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Functional Materials for Acoustics
We engineer and study new functional materials for acoustics and use them to control wave propagation. We are especially interested in composite materials (periodic, random, locally resonant or with gradients of properties). These materials can enable tunable wavefront control or exhibit extraordinary scattering and absorption properties. We achieve high-fidelity propagation control with practical materials that can find applications in the development of advanced devices for complex wavefront shaping, ultrasonic imaging, sound attenuation or acoustic stealth. Another aspect of our research focuses on the mechanical effect of sound waves interacting with distant targets. We are developing new strategies to trap, manipulate and deform soft and biological matter without any physical contact.
Acoustic Waves in Complex Media
Contact
Physics of waves in disordered media is a booming and fascinating research area. To investigate the richness and the complexity of exotic wave phenomena such as negative refraction or the Anderson localization, it is essential to have rationally designed “model systems”. For this purpose, we collaborate with the colleagues from physical chemistry laboratories of our campus (CRPP & LOF) who are able to produce various customized acoustic materials by using soft-matter techniques (emulsion-templating, microfluidics…). Therefore we have the opportunity to accurately study the transport of ultrasonic waves in heterogeneous media of many different types such as emulsions, suspensions, porous materials, etc.
Soft Acoustic Metamaterials
A promising way to get unusual acoustic properties such as a negative/zero acoustic index is to use 3D locally resonant metamaterials composed of sub-wavelength resonant particles exhibiting large mechanical contrasts with the surrounding medium. As an example, we reported the first ever 3D metafluid with a negative acoustic index by taking benefit from the strong low-frequency Mie-type resonances of porous microbeads with very low sound speeds randomly dispersed in aqueous yield-stress fluids. These resonant particles were made of soft porous silicone rubber or soft porous silica.
Related publications:
T. Brunet et al., Science 342 , 323 (2013)
T. Brunet et al., Nat. Mater. 14 , 384 (2015)
T. Brunet et al., EPJ Appl. Metamat. 2 , 3 (2015)
S. Raffy et al., Adv. Mater. 28 , 1760 (2016)
R. Poupart et al, RSC Advances. 10, (2020)
Soft gradient-index metasurfaces
As an alternative to 3D metamaterials, the recent emergence of metasurfaces has introduced new opportunities to realize wavefront shaping without restriction (e.g., directivity design, focusing, and singular field generation). We recently reported on a new class of acoustic gradient-index metasurfaces engineered from soft graded-porous silicone rubber with a high acoustic index for broadband ultrasonic 3D wavefront shaping in water. The functionalities of these soft flat lenses was illustrated through various experiments, which demonstrated beam steering and beam focusing as well as vortex beam generation.
Related publications:
A. Kovalenko et al., Soft Matter 12, 5154 (2016)
A. Kovalenko et al., Soft Matter 13, 4526 (2017)
A. Ba et al., Sci. Rep. 7, 40106 (2017)
Y. Jin et al., Nat. Comm. 10, 143 (2019)
R. Kumar et al., Journal of Porous Materials (2020)
Ultrasonic wave transport in resonant emulsions
The realization of highly monodisperse resonant systems, such as resonant emulsions, has allowed us to accurately describe all the key transport parameters of classical waves in disordered media. We recently reported on the impact of strong scattering resonances on ballistic and diffusive wave transport and we have also demonstrated the important influence of the relative refractive index of scattering inclusions on energy transport. As the next step, we aim at evidencing much more complex wave phenomena such as the Anderson localization that should occur in highly concentrated or highly resonating suspensions.
Related publications:
T. Brunet et al., Appl. Phys. Lett. 101, 011913 (2012)
B. Mascaro et al., J. Acoust. Soc. Am. 133, 1996 (2013)
T. Brunet et al., Phys. Rev. Lett. 111 , 264301 (2013)
B. Tallon et al., Phys. Rev. Lett. 119, 164301 (2017)
B. Tallon et al., Phys. Rev. B 101, 054202 (2020)
Contactless Micromanipulation with Acoustic Waves
Contact
A promising way to handle and manipulate matter at the microscale is to use the acoustic radiation stresses (force and torque) that originate from the interaction between an incident wave and a target. Single-beam acoustical tweezers have recently been developed to trap, manipulate and study individual objects of interest at the microscale (e.g. droplets, bubbles, soft matter and biological structures) without any physical contact.
We investigate the physical mechanisms of various wave/matter interactions by systematically combining theoretical models with innovative experimental setups that integrate advanced acoustical and optical techniques. These include wavefront shaping, fibre-optic pressure measurements, and high-speed optical microscopy.
Related publications:
D. Baresch et al., Journ. Acous. Soc. Am., 113, (2013)
D. Baresch et al., Phys. Rev. Lett, 116, (2016)
D. Baresch et al., Phys. Rev. Lett, 121, (2018)
D. Baresch & V. Garbin, PNAS, (2020)
D. Wu et al., bioRxiv, (2019)
General problems of elastic wave propagation in structured anisotropic materials
Contact
Olivier Poncelet, Alexander Shuvalov & Christophe Aristegui
Anisotropy of crystals, which implies large number of independent material parameters, significantly diversifies acoustic phenomena but also complicates direct derivation of their characteristics and actually precludes finding exact closed-form solutions. At the same time, anisotropy is also prone to impede numerical calculations. This is all the more so in the case of materials with discretely or continuously varying properties. That is why any kind of analytical insight into the general properties of elastic waves in anisotropic and/or structured materials remains indispensable even though it is usually confined to approximate or averaged evaluations, asymptotical trends, upper and lower bounds, analysis of existence of wave solutions, etc. It is also a means for developing tractable models for evaluating wave propagation in the new generation of composite materials.
Our research record, which has been and is being conducted in the above context, includes the following topics and milestones:
• asymptotics of the dispersion spectra of guided waves travelling in anisotropic plates made of elastic or piezoelectric, uniform or functionally graded materials under free or loaded boundary conditions;
• general formalism for wave propagation in cylindrically and spherically anisotropic radially inhomogeneous elastic media;
• homogenization into the Willis-type model and the effective speed of sound in 1D-, 2D- and 3D-periodic elastic and piezoelectric continua (phononic crystals);
• methods of monodromy-matrix and resolvent for analysing and calculating dispersion spectra of surface waves in 1D- and 2D-periodic substrates and waveguides;
• tunable wave properties in piezoelectric crystals with periodically embedded electrodes controlled via external network of capacitors;
• existence and possible number of surface and interfacial wave solutions in elastic and piezoelectric superlattices of arbitrary anisotropy.
Related publications:
A.L. Shuvalov, O. Poncelet, “On the backward Lamb waves near thickness resonances in anisotropic plates”, Int. J. Solids Struct. 45 (11-12), 3430-3448 (2008)
C. Aristégui, A.L. Shuvalov, O. Poncelet, M. Caleap, “Trapping of shear acoustic waves by a near-surface distribution of cavities”, J. Acoust. Soc. Am. 125(2), 628-631 (2009)
A.N. Norris, A.L. Shuvalov, “Wave impedance matrices for cylindrically anisotropic radially inhomogeneous elastic solids”, Q. J. Mech. Appl. Math. 63(4), 401-435 (2010)
A.L. Shuvalov, A.A. Kutsenko, A.N. Norris, O. Poncelet, “Effective Willis constitutive equations for periodically stratified anisotropic elastic media”, Proc. R. Soc. A 467(2130), 1749-1769 (2011)
A.N. Norris, A.L. Shuvalov, A.A. Kutsenko, “Analytical formulation of three-dimensional dynamic homogenization for periodic elastic systems”, Proc. R. Soc. A 468(2142), 1629-1651 (2012)
M.E. Korotyaeva, A.A. Kutsenko, A.L. Shuvalov, O.Poncelet. “Resolvent method for calculation dispersion spectra of the shear waves in the phononic plates and waveguides”, J. Comput. Acoust. 22(3), 1450008 (2014)
A.N. Darinskii, A.L. Shuvalov, O.Poncelet, A.A. Kutsenko. “Bulk longitudinal wave reflection/transmission in periodic piezoelectric structures with metallized interfaces”, Ultrasonics 63, 118-125 (2015)
A.A. Kutsenko, A.J. Nagy, X. Su, A.L. Shuvalov, A.N. Norris. “Wave propagation and homogenization in 2d and 3d lattices: A semi-analytical approach”, Q. J. Mech. Appl. Math. 70(2), 131-151 (2017)
A.A. Kutsenko, A.L. Shuvalov, O.Poncelet. “Dispersion spectrum of acoustoelectric waves in 1D piezoelectric crystal coupled with 2D infinite network of capacitors”, J. Appl. Phys. 123, 044902 (2018)
A. N. Darinskii, A. L. Shuvalov. “Existence of surface acoustic waves in one-dimensional piezoelectric phononic crystals of general anisotropy”, Phys. Rev. B 99, 174305 (2019).
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