Sound Waves Suspend Objects in Mid-Air
Imagine particles hanging in mid-air, defying gravity, as if held by an invisible force. This is acoustic levitation. When sound waves converge, they create zones of high pressure, trapping objects at their peaks. Change the sound, and the objects move or drop.
Details and Theory
Acoustic levitation is achieved by utilizing the mechanical momentum of sound waves, known as acoustic radiation forces. When strong forces from all directions converge on an object, it can be stably suspended in mid-air. In the Acoustic Levitator, an array of small ultrasonic transducers emits acoustic waves, generating a standing wave pattern. This standing wave has regions of high pressure called nodes, where particles are trapped due to the acoustic radiation forces.
The arrangement of the transducers is crucial to achieving stable levitation. The transducers are oriented and spaced to create a geometric focus, enhancing trapping forces. By altering the excitation signal of the transducers, the horizontal movement of the trapped particles can be controlled.
Acoustic levitation has various applications, from container-less transportation and pharmaceutical research to fluid dynamics studies and even levitating small living organisms. The Acoustic Levitator provides a way to explore the interaction between sound waves and matter, showcasing the potential of using sound for precise manipulation and experimentation.