A team of Japanese researchers have successfully carried out an experiment using the force of ultrasound to enable controlled levitation and manipulation of light objects.
Being able to levitate and manipulate objects in the air is an idea that seized people’s imagination long ago. Today levitating objects is not an innovation in itself as it has for some time been possible to raise objects using ultrasound waves and move them in linear fashion. Now however a team of three researchers, including 26-year-old Tokyo University student Yoichi Ochiai, have taken this a step further, successfully making small items fly around in three dimensions. They have proved they can move the objects at will in any direction by controlling the sound waves.
The principle of acoustic levitation
The researchers set up a system which uses sound waves as an agent of movement. They built a box containing four antennae in an ultrasonic phased array, i.e. a group of antennae whose sound waves can be directed. The ultrasound waves converge on to a common point and generate acoustic axes. The trio of researchers experimented with a variety of low-density objects, including small polystyrene balls, which became trapped at the intersection of the acoustic axes and remained suspended in the air. The researchers then succeeded in moving the balls in any direction by directing the ultrasound waves.
The system uses transducers with a frequency of 40 kHz (as a comparison, the range of human hearing is limited to 20 kHz) but the researchers aim to lower the frequency to 25 kHz with a view to developing a better system that would consume less energy. They also hope to be able to levitate and set in motion larger objects. Over the next five years they are hoping to attract the interest of the pharmaceutical industry in their technology, which could be used for manipulating toxic products remotely. Space is also an environment in which controlled object levitation and manipulation would be useful and Yoichi Ochiai has revealed he has ambitions in this direction. “I dream of being able to win over the space industry,” he stated.
Photos and videos of the experiment are available on Yoichi Ochiai’s site at: http://96ochiai.ws/3DOFacoustic