Ultrasonic sharp autofocusing with acoustic metasurface

Jiang, Xue; Li, Yong; Ta, Dean; Wang, Weiqi

doi:10.1103/physrevb.102.064308

Cited by 39 publications

(14 citation statements)

References 43 publications

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“…From Fig. 3, one can observe a broad parameter's space for realizing subwavelength focusing with FWHM less than 0.5 which the physical mechanism is the interference and diffraction of the gradient sub-sources in the near field region [41,42] with the near field length defined as LN= D 2 /4. When the ratio F/D goes above 0.3 and 0.4, the FWHM becomes larger than 0.5 for the simulation and analytical methods, respectively.…”

Section: Sub-wavelength Focusingmentioning

confidence: 99%

Elastic Metasurfaces for Deep and Robust Subwavelength Focusing and Imaging

et al. 2021

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Metasurfaces are planar metamaterials with a flat surface and a subwavelength thickness that are able to shape arbitrary wavefronts such as focusing or imaging. There is a broad interest in the literature about subwavelength focusing/imaging based on bulk metamaterials while the utilization of metasurfaces for elastic waves has rarely been reported. Here, we present a new type of elastic metasurface consisting of a line of gradient resonant pillars for robust deep subwavelength focusing and imaging of elastic waves in a plate. Numerical approaches supported by analytic Huygens-Fresnel demonstrations show that the subwavelength full width at half maximum (FWHM) behaves linearly as a function of the ratio F/D where F is the measured focal length and D the metasurface length. We discuss the range of F/D where FWHM remains smaller than half a wavelength in the near field. The focal length F and the FWHM exhibit stable performances when submitted to disorder perturbations in the geometrical parameters and to frequency fluctuations.We show that the enhanced focusing resolution with smaller FWHM can be very beneficial for energy harvesting since the output electric power can be increased by more than one order of magnitude. The proposed elastic metasurfaces bring a new way for high resolution focusing and imaging which is useful for applications in various domains such as energy harvesting, wave sensing, communication, nondestructive evaluation.

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Section: Sub-wavelength Focusingmentioning

confidence: 99%

Elastic Metasurfaces for Deep and Robust Subwavelength Focusing and Imaging

et al. 2021

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“…[11] Afterward, acoustic metasurfaces, [12,13] which are used to modulate the wave fronts by controlling the wave responses of each meta-atom, have aroused increasing attention from researchers. Indeed, due to their potential application values in many fields, a series of practical works has been reported, including acoustic communication, [14][15][16] acoustic hologram, [17][18][19] acoustic focusing, [20][21][22][23] and anomalous reflection and refraction. [24][25][26][27] Acoustic asymmetric transmission (AAT), in which an incident acoustic wave is permitted to propagate forward while blocked backward, has been investigated since the first prototype of an acoustic diode was proposed due to its potential utility in engineering fields.…”

Section: Introductionmentioning

confidence: 99%

Tunable Asymmetric Transmissions via Anisotropic Acoustic Metamaterials

Zhang

Bai

et al. 2021

Physica Rapid Research Ltrs

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An acoustic prism for asymmetric transmissions is proposed, designed, and fabricated by an anisotropic metamaterial composed of an array of controllable C-shaped meta-atoms. Due to the anisotropic configuration of the meta-atom, the effective refractive index of the prism can be continuously tuned by rotating the meta-atom. It is demonstrated that the transmitted wave direction of an incident acoustic wave from one direction can be controlled in real time, as the rotation angle of meta-atom changes gradually. Meanwhile, the incident acoustic wave from the opposite direction will be blocked all the time. Furthermore, a wide range of transmitted angles can be obtained by reshaping the prism, which can work in a broadband (4400-5200 Hz). The results are verified through theoretical predictions, numerical simulations, and experimental measurements. The method can be extended to realize other kinds of tunable asymmetric transmissions of waves via anisotropic metamaterials with controllable meta-atoms.

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“…1c. Here, a high gain acoustic antenna forms an acoustic beam using an admittance-modulated metasurface composed of periodic subwavelength grooves with a sinusoidal depth profile, and the periodic groove profile can be modulated as an independent binary metasurface to control the beam angle and beamwidth [21][22][23] . Recently, using optimized design methods 24,25 , advanced ultrasonic acoustic-focusing devices with simplified architectures have been developed to achieve subwavelength imaging and active acoustic focusing.…”

mentioning

confidence: 99%

Planar ultrasonic transducer based on a metasurface piezoelectric ring array for subwavelength acoustic focusing in water

Hur

Choi

Yoon

et al. 2022

Sci Rep

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The development of a new ultrasonic transducer capable of improved focusing performance has become a necessity to overcome the limitations of conventional ultrasonic transducer technology. In this study, we designed and optimized a metasurface piezoelectric ring device, and using multiphysics finite element analysis, we examined the performance of a planar ultrasonic transducer consisting of this device, a matching layer, a backing layer, and housing in producing a needle-like subwavelength focusing beam in water. For practical experiments, a metasurface piezoelectric ring device was fabricated using a laser ablation process. Subsequently, using a pulse-echo test, we found that the − 6 dB bandwidth of a planar ultrasonic transducer with a center frequency of 1.0 MHz was 37.5%. In addition, the results of an ultrasonic-focusing performance test showed that the full width at half-maximum of the axial subwavelength focusing beam was 0.78λ, and the full lateral width at half-maximum of the subwavelength lateral focusing beam was 7.03λ at a distance of 10.89λ. The needle-like focused ultrasonic beam technology implemented with a piezoelectric ring array based new planar ultrasound transducer is expected to be used in high-resolution imaging devices or medical ultrasound focusing devices in the future.

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Ultrasonic sharp autofocusing with acoustic metasurface

Cited by 39 publications

References 43 publications

Elastic Metasurfaces for Deep and Robust Subwavelength Focusing and Imaging

Elastic Metasurfaces for Deep and Robust Subwavelength Focusing and Imaging

Tunable Asymmetric Transmissions via Anisotropic Acoustic Metamaterials

Planar ultrasonic transducer based on a metasurface piezoelectric ring array for subwavelength acoustic focusing in water

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