Our project centres around the principle of acoustic levitation – the use of ultrasonic sound waves that undergo constructive interference to create nodes that are able to contain small objects, allowing them to levitate.
There are two ways by which we can levitate these small objects.
One is by creating standing waves. This occurs when two waves of the same frequency are emitted towards each other. The incident waves from the sources interfere with the reflected waves. This interference occurs in such a manner that specific points along the medium appear to be standing still. The observed pattern is known as a standing wave pattern. Such patterns are only created within the medium at specific frequencies of vibration. These frequencies are known as harmonic frequencies, or merely harmonics.
Another method we can use to levitate is by using an acoustic radiative force. This method depends on the generation of a non-linear acoustic field below the object we want to levitate. Such a field would produce a force known as the acoustic radiative force which can counter gravity, causing levitation to occur.
By changing the frequency of the waves emitted, we are able to change the position of these nodes containing the objects hence causing the objects to move along with the nodes.