Vortex educations can be different, from huge and deadly tornadoes to small and safe whirlwinds which can't be seen unaided by a look. And if from big whirlwinds and a tornado it is necessary to escape, tiny whirlwinds it is possible to force to work for advantage of science. From such tiny whirlwind created by means of ultrasonic waves, scientists created some kind of sound lasso, a trap in which it is possible to catch and by means of which it is possible to move different microscopic objects.
In article published in the Applied Physics Letters online edition, researchers from department of mechanical engineering of Bristol university and university of medical sciences and technologies of Dundee institute showed that various tiny particles, such as living cells and various nanoparticles can be ensnared a sound whirlwind. This whirlwind operating as a sound lasso, it is possible to operate rather simply, slowly and carefully moving the caught microscopic particles. Such technology can be used for the solution of rather wide range of tasks, such, as "assembly" of artificial fabrics from a set of separate cages, assembly of difficult nanomaterials and metamaterials.
At the heart of the developed technology the acoustic whirlwinds described by so-called mathematical functions of Bessel lie. These functions define configuration and dynamics of a sound lasso, a vector of an impulse of its linear and rotary moment which can force the captured objects to rotate or move in the necessary direction.
The sound lasso represents the round device as a part of which there are 16 sources of ultrasound, each of which is capable to reproduce the sound fluctuations extending in the certain direction and having own frequency, amplitude and phase shift. The combination of the sound waves radiated by all sources, leads to creation in the operational volume of the device of the vortex sound fluctuations having in advance calculated characteristics. Areas of minima of these fluctuations are actually a trap, and movements of fronts of pressure of a sound wave forces the caught particles to move in the necessary direction.
Bruce Drinkuoter (Bruce Drinkwater), the professor in the field of ultrasonic technologies of department of mechanical engineering of Bristol university, tells: "Our researches showed that by means of a whirlwind of an ultrasonic lasso we can take and move to the right place of a particle on any trajectory. But the most interesting is that our method is absolutely contactless, safe and it perfectly is suitable for manipulation with such things, as the cages considered under a microscope. With small modifications the technology developed by us can become part of product production lines on which elements of human fabrics and artificial organs" will be made.