CE08 - Matériaux métalliques et inorganiques et procédés associés

Broadband Extraordinary Acoustic Transmission for super-resolution imaging – BEAT

Submission summary

Wave concentration beyond the diffraction limit by transmission through subwavelength structures has proved to be a milestone in high resolution imaging. However, despite the advantages of extraordinary transmission in concentrating wave energy to tiny regions, its potential in sub-wavelength imaging has never been demonstrated. A device capable of generating an image by capturing evanescent waves using this principle could visualize the details of an object and extract its subwavelength features. In the BEAT project, we are proposing to tackle this barrier by developing an acoustic metamaterial device for sub-wavelength and broadband focusing of bulk waves at MHz frequencies.

Extraordinary transmission through small subwavelength apertures, i.e. the passage of more wave energy than expected by geometrical considerations, is a metamaterial-related phenomenon based on local resonances, not exclusive to electromagnetic waves. The BEAT project is first proposing to extend the principle of extraordinary acoustic transmission (EAT) to the MHz range by using an experimental approach combined with numerical simulations. This project has the ambition to experimentally demonstrate for the first time the EAT phenomenon for bulk waves in solids. The aim of this project is to develop a proof-of-concept device capable of reducing the focal spot below the diffraction limit and adaptable on commercial piezoelectric transducers. The physical device to be designed will be built, characterized and finally coupled to commercial piezoelectric flat transducers as primary field source.

As most of the EAT systems are based on meta-resonance, the working frequency regime is inherently narrow band, this is a major drawback in pulse-echo-based imaging. Enlarging the EAT phenomenon to a wide frequency range is a challenge to address highly resolved future sensing applications. The second objective of the BEAT project is to experimentally demonstrate broadband EAT (BEAT) for the first time. A compromise should be elucidated between the efficiency of the prototype and the fabrication feasibility. To this aim, different solutions of broadband acoustic metamaterial will be envisaged and correlated with the experimental constraints.

By proposing an experimental and broadband device, the BEAT project will lead to the first demonstration of the super-resolution imaging based on EAT process in solids. The different prototypes developed in the project will be tested in imaging context by using an experimental approach correlated with numerical models. The lateral resolution and in-depth resolution of the BEAT microscopes will be investigated. Moreover, phase and amplitude behavior of the reflection coefficient will be studied with different media samples to extract the position and the mechanical properties of the sample with a unique measurement in order to demonstrate complex topography measurement capabilities. The super-resolution capabilities will be exploited by studying the influence of a rigid-like object position in water on the amplitude and the phase pressure fields in 2D-scan mode.

By improving the spatial resolution of acoustic images under the diffraction limit with a broadband EAT-based metamaterial, the BEAT project will lead to new opportunities for non-destructive evaluation and testing, imaging and sensing.

Project coordination

Thibaut DEVAUX (Matériaux, Microélectronique, Acoustique, Nanotechnologies)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

Hokkaido University / Laboratory of Applied Solid State Physics
GREMAN Matériaux, Microélectronique, Acoustique, Nanotechnologies

Help of the ANR 200,704 euros
Beginning and duration of the scientific project: - 42 Months

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