Sonomaglev: Combining acoustic and diamagnetic levitation

Acoustic levitation and diamagnetic levitation are experimental methods that enable the contact-free study of both liquid droplets and solid particles. Here, we combine both the techniques into a single system that takes advantage of the strengths of each, allowing for the manipulation of levitated spherical water droplets (30 nl-14 mu l) under conditions akin to weightlessness, in the laboratory, using a superconducting magnet fitted with two low-power ultrasonic transducers. We show that multiple droplets, arranged horizontally along a line, can be stably levitated with this system and demonstrate controlled contactless coalescence of two droplets. Numerical simulation of the magnetogravitational and acoustic potential reproduces the multiple stable equilibrium points observed in our experiments.