Waveguide based acoustic levitation device for moving objects in a large volume

Moving objects contactlessly in a large addressable 3D space usually requires moving parts of an acoustic levitation device or running optimization algorithms in conjunction with it. We propose a computationally lightweight approach to trap objects in a narrowed beam and transport them within a 3D volume by a stationary setup. This is achieved by attaching an ultrasonic phased array to a 3D-printed acoustic waveguide, which reduces the inter-element spacing of the array to half of its emitted wavelength. The attached waveguide allows electronically steering the sound beam of the ultrasonic phased array while reducing the near-field length and grating lobes at the same time. By combining those capabilities with a concave reflector, we can move multiple objects in a spherical cone at the same time. Up to twelve objects can be levitated for an apex angle of 80°. The absolute positioning error is below 7° and has a standard deviation of 1.29°. Some nodes in the center of the acoustic levitator can also be steered inside an apex angle of 120°. With this levitation device, we demonstrate the benefits of combining passive and active means of shaping a sound field to manipulate acoustically levitated objects.