Design and experimental demonstration of broadband acoustic pressure enhancing passive metafluids

Abstract

This paper presents the design and experimental demonstration of a passive broadband acoustic pressure enhancing metafluid in air. The design is optimized for fabrication via three-dimensional (3D) printing and takes advantage of the property of acoustic pressure to enhance sound as the sound passes with minimal insertion loss from the background medium into a high impedance fluid. Numerical simulations and experimental measurements of the fabricated structure show that the metafluid enhances the sound pressure level by 7 dB in more than one octave without introducing sound distortions. Moreover, the metafluid is subwavelength in size and does not increase the aperture of the sensor. These results provide an excellent path toward improving the sensitivity of compact acoustic sensors without employing active elements.

Reconfigurable large-scale bulk metamaterials for broadband ultrasonics

“…Figure 2(b) shows the effective refractive index and insertion loss (due to both absorption and reflection) versus the perforation size d. These values are calculated from the incident ( p i ), reflected ( p r ), and transmitted ( p t ) pressures obtained from simulations using a method widely used for calculating effective acoustic properties of metamaterials in air [12,16,17,[38][39][40].…”

“…The second source of insertion loss consists of unwanted reflections caused by poorly matched unit cells to the air background. To minimize reflections, we add impedance matching sections at the input and output apertures following a method presented in [18,38,39].…”