Morphing Surfaces Enable Acoustophoretic Contactless Transport of Ultrahigh-Density Matter in Air

Abstract

The controlled contactless transport of heavy drops and particles in air is of fundamental interest and has significant application potential. Acoustic forces do not rely on special material properties, but their utility in transporting heavy matter in air has been restricted by low power and poor controllability. Here we present a new concept of acoustophoresis, based on the morphing of a deformable reflector, which exploits the low reaction forces and low relaxation time of a liquid with enhanced surface tension through the use of thin overlaid membrane. An acoustically induced, mobile deformation (dimple) on the reflector surface enhances the acoustic field emitted by a line of discretized emitters and enables the countinuos motion of heavy levitated samples. With such interplay of emitters and reflecting soft-structure, a 5 mm steel sphere (0.5 grams) was contactlessly transported in air solely by acoustophoresis.

Aerosol manipulation by acoustic tunable phase-control at resonant frequency

“…A number of papers [6,7,11,12,17,21,[27][28][29][30] on particle manipulation using ASW have indicated that aerosols in ASW field are exerted an external acoustic radiation force. The acoustic radiation force results from the acoustic radiation pressure [11,31].…”

“…Their particle diameter is in the range of 1-3 mm. Daniele et al [11] designed an acoustic macro platform for levitating a steel sphere of 5 mm in air using ASW of 25 kHz. Therefore, it is appropriate that we study the effect of the phase of ASW on the aerosol manipulation at low resonant frequency, especially in macroscopic cavity.…”

“…Other relative important researches are the acoustic manipulation [9] and levitation [10][11][12] of micro-and macro scale particles in gas. Karpul et al [9] designed industrial acoustic filters to manipulate particles, and showed the advantage of optimizing operating and structure factors of acoustic filter on achieving better manipulation.…”

The Advantage of Aerosol Manipulation by Twin Types of Acoustic Resonances

“…The corresponding resonance type generally focuses on the unique one-dimension harmonic waveguide [7], [11], [15]. However, the number of acoustic resonance type is relatively fewer considered in the general harmonic mechanism of the unique waveguide.…”

“…In the current studies [7]- [9], [11], [15], the acoustic resonance design of aerosol manipulation device is generally used to generate high sound pressure without high energy consumption based on the impendence matching characteristic [15] between device and air. The corresponding resonance type generally focuses on the unique one-dimension harmonic waveguide [7], [11], [15].…”