What is the ultimate capability of acoustophoretic volumetric displays?

Advances in acoustophoresis have allowed the recent development of a free-space volumetric display called an Acoustophoretic Volumetric Display (AVD) that can render 3D graphics observable without obstructions. The current generation of AVD can render simple vector graphics in real-time, but larger and complex graphics require 10s or more to render. Here, we present a generalized model of an AVD and use this to understand its performance limits; in particular, we answer the question of how large a display (1:1 raster screen) can be created. We show that AVD performance is affected by the size and properties of the particle, along with the viscosity of the surrounding fluid. Optimal performance is achieved when the viscous drag force and inertial force are minimized relative to the acoustic radiation force. Our model suggests that, for expanded polystyrene particles ( rho p = 19 kg m - 3), a screen size of up to 117mm by 117mm can be rendered at 10Hz with an acoustic frequency of 20kHz and an acoustic pressure amplitude of 25kPa.