Multifunction acoustic modulation by a multi-mode acoustic metamaterial architecture

Abstract

Exotic acoustical features, like acoustic transparency, ultrasonic beam focusing, acoustic band gap and super lensing capability using a single metamaterial architecture is unconventional and unprecedented in the literature, demonstrated herein. Conventional metamaterials can focus an ultrasonic beam at specific frequency which results into unwanted distortion of the output wave fields at neighboring sonic frequencies in the host medium. However, ultrasonic wave focusing by virtue of negative refraction and simultaneous transparency of the metamaterial at sonic frequencies are uncommon due to their frequency disparity. To circumvent this problem and to avoid the unwanted distortion of wave at sonic frequencies, metamaterial with an array of butterfly-shaped thin ring resonators are proposed to achieve the beam focusing at ultrasonic frequency (37.3 kHz) and keep the structure transparent to the sonic frequencies (<20 kHz). The butterfly metamaterial with local ring resonators or butterfly crystals (BC) were previously proposed to create wide band gaps (∼7 kHz) at ultrasonic frequencies above 20 kHz. However, in this study a unique sub-wavelength scale wave focusing capability of the butterfly metamaterial utilizing the negative refraction phenomenon is demonstrated, while keeping the metamaterial block transparent to the propagating wave at lower sonic frequencies below the previously reported bandgaps.

A football-like acoustic metamaterial with near-zero refractive index and broadband ventilated sound insulation

“…The research of acoustic metamaterials was initially inspired by the analogy of electromagnetic metamaterials [1][2][3][4]. On the basis of research on electromagnetic metamaterials, some scholars have turned their attention to the research of acoustic metamaterials with single and double negative properties and zero refractive index, to realize the supernormal acoustic wave transmission characteristics such as subwavelength imaging [5][6][7], acoustic tunneling [8][9][10], acoustic prism [11][12][13] and target stealth [14][15][16][17]. Acoustic metamaterials can exhibit double negative characteristics, with negative bulk modulus achievable through monopole resonance and negative mass density achievable through dipole resonance.…”

Dual band Vis-IR absorber using bismuth based helical metamaterial surface

“…[4]. These extraordinary ability of metamaterial, dragged it at the center of interest to push the boundaries of nano-devices upto next level ranging form communication devices; antennas [5], modulators [6], wireless devices [7,8] to energy efficient conversion devices; solar cells [9], absorbers [10]. The most interesting feature of metamaterial is its sub-wavelength size for visible and IR applications and absorption of various bands of electromagnetic spectrum.…”

Solid Lipid Nanoparticles Enhanced the Neuroprotective Role of Curcumin against Epilepsy through Activation of Bcl-2 Family and P38 MAPK Pathways

“…According to the World Health Organization, epilepsy is one of the most frequent neurological diseases, approximately 0.4%−1% of the population suffering worldwide. 1 Epilepsy can result from stroke, traumatic brain injury, or nervous system infection, with pathological features like abnormal discharge of nerve cells, neuron loss and glial activation, and convulsive events finally occurring. 2 Nearly a third of patients fail to respond to existing antiepileptic drugs (AEDs).…”