A new class of tunable hypersonic phononic crystals based on polymer-tethered colloids

Abstract

The design and engineering of hybrid materials exhibiting tailored phononic band gaps are fundamentally relevant to innovative material technologies in areas ranging from acoustics to thermo-optic devices. Phononic hybridization gaps, originating from the anti-crossing between local resonant and propagating modes, have attracted particular interest because of their relative robustness to structural disorder and the associated benefit to ‘manufacturability'. Although hybridization gap materials are well known, their economic fabrication and efficient control of the gap frequency have remained elusive because of the limited property variability and expensive fabrication methodologies. Here we report a new strategy to realize hybridization gap materials by harnessing the ‘anisotropic elasticity' across the particle–polymer interface in densely polymer-tethered colloidal particles. Theoretical and Brillouin scattering analysis confirm both the robustness to disorder and the tunability of the resulting hybridization gap and provide guidelines for the economic synthesis of new materials with deliberately controlled gap position and width frequencies.

Nanophononics: state of the art and perspectives

“…Arranging polymer-decorated colloidal particles in periodic lattices permits the realization of two-or three-dimensional phononic crystals, in which the dispersion relations of hypersonic acoustic modes can be controlled by tuning the features of the polymer linkers and the particle-polymer interface [75,76]. This approach introduces further degrees of freedom on top of the nanostructure length scales, commonly employed to engineer phonons in hard materials.…”

Soda Cans Metamaterial: A Subwavelength-Scaled Phononic Crystal

“…We have therefore reinterpreted this band gap in terms of Fano interferences [33,66] since it is clearly the interaction between a continuum of modes (the free space waves) and a resonator [34]. Note that there are several works in the acoustic community that have tried to mix in the same frequency range the "hybridization band gap" and the Bragg gap that is due to the periodicity of the medium and mostly occurs when the lattice constant is half a wavelength [62,[67][68][69].…”

Elastic Wave Control Beyond Band-Gaps: Shaping the Flow of Waves in Plates and Half-Spaces with Subwavelength Resonant Rods

“…In the field of acoustic imaging, the tailored control of hypersound (elastic waves at GHz frequencies), used for cell or other nano-compound imaging or energy conversion and harvesting (Davis and Hussein, 2014;Della Picca et al, 2016), is emerging as one of the most promising applications of energy trapping and signal enhancement through metamaterials. Furthermore, at this small scale, novel nanofabrication techniques deliver the tailoring possibilities required for graded devices (e.g., Alonso-Redondo et al, 2015;Rey et al, 2016). Among the possible resonant metasurface designs for elastic waves proposed in recent years (e.g., Baravelli and Ruzzene, 2013;Miniaci et al, 2015;Lee et al, 2016;Matlack et al, 2016;Galich et al, 2017;Tallarico et al, 2017), the one made of a cluster of rods (the resonators) (Pennec et al, 2008;Wu et al, 2008;Achaoui et al, 2011;Colombi et al, 2016c) on an elastic substrate has revealed superior characteristics and versatility of use in particular toward the fabrication of graded design.…”