GRIPP: an automated computer-aided design tool for generating 3D printable gradient index acoustic devices

Abstract: Gradient index (GRIN) acoustic devices have spatially inhomogeneous refractive index profile and allow flexible control of the propagation of acoustic waves. Previous GRIN acoustic lenses are mostly inherently two-dimensional designs that are difficult to be extended to all three dimensions. Besides, manually designing the spatially inhomogeneous structure is both time-consuming and error-prone. In this work, we proposed and numerically verified an automated computer-aided design tool: GRadient Index Pick-and-Place (GRIPP) algorithm, for generating three-dimensional GRIN acoustic wave controlling devices with scalable and 3D printable structures. The algorithm receives as inputs a spatial distribution of refractive index and a pre-defined library of gradient index unit cells, and outputs a 3D model of GRIN device that is ready to be 3D printed. The tool enables rapid design and realization of a large variety of 3D GRIN acoustic devices, which can be useful in areas such as speaker system design, airborne ultrasonic sensing, as well as therapeutic ultrasound.