'Ultrasonic Vortex' Lasso Can Move Around Microscopic Living Cells

For the first time, a micro-scale "sonic lasso" was demonstrated that can grip and move around cells and other microscopic objects. Researchers at the University of Bristol's Department of Mechanical Engineering and University of Dundee's Institute for Medical Science and Technology, list possible applications such as assembling human tissue from a collection of cells and assembling nanomaterials as the new possibilities of their technology that uses a "spinning ultrasonic vortex", which acts as a lasso that can be controlled and moved.

"Our research has shown we can grip and move particles pretty much anywhere and along any path," said Bruce Drinkwater, Professor of Ultrasonics in the Department of Mechanical Engineering, who led the study. "The impressive thing is that it is completely non-contact, harmless, and ideal for moving delicate things, such as cells, around under a microscope. With further development this could be used to assemble human tissue as part of a tissue engineering production line."

The main mechanism that the scientists use are acoustic vortices, known as Bessel-functions, that trap and position microparticles. They explain that like a rope lasso, the waves carry both linear and rotational momentum, so they can cause the objects to spin as well as move.

A circular device, made up of 16 ultrasound sources, generates and manipulates an acoustic field within a chamber, trapping microparticles and clusters of microparticles.

Changes in the phase of the sinusoidal signals applied to the sources result in the movement of the Bessel-function pressure field and therefore the microparticles.

Paper:

Charles R. P. Courtney et al., Dexterous manipulation of microparticles using Bessel-function acoustic pressure fields, Applied Physics Letters, 2013, DOI: 10.1063/1.4798584