A team of researchers in Switzerland have developed a way of levitating and transporting small objects using nothing but sound. Using ultrasonic waves that is, sound waves whose frequencies are too high for humans to hear, scientists at the Swiss Federal Institute of Technology in Zurich have made water droplets, instant coffee crystals, styrofoam flakes, and a toothpick, among other objects, hang in mid air, move along a plane, and interact with each other.
https://www.csmonitor.com/Science/2013/0716/Scientists-use-sound-waves-to-levitate-manipulate-matter