Caption: The
research team have created three-dimensional acoustic fields
with shapes such
as fingers, twisters and cages. These acoustic fields are the
first acoustic
holograms that can exert forces on particles to levitate and
manipulate them.
Credit: Image courtesy of Asier Marzo, Bruce Drinkwater
and Sriram
Subramanian © 2015
(October 27, 2015) The
world’s first sonic tractor beams that can lift and move objects using
soundwaves have been built by a team that includes researchers at the
University of Sussex.
Tractor beams are mysterious rays that can grab and lift
objects. The concept was created by science-fiction writers but has since come to fascinate scientists
and engineers.
Researchers at the Universities of Sussex and Bristol, in
collaboration with Ultrahaptics, have now built a working tractor beam that
uses high-amplitude sound waves to generate an acoustic hologram that can pick
up and move small objects.
Asier Marzo, PHD
student and lead author,
levitating a polystyrene ball with soundwaves.
The technique, published in Nature Communications today (27
October 2015), could be developed for a wide range of applications. For
example, a sonic production line could transport delicate objects and assemble
them, all without physical contact. Or a miniature version could grip and
transport drug capsules or microsurgical instruments through living tissue.
Caption: Holograms
are tridimensional light-fields that can be projected from a two-dimensional
surface. The
researchers have created acoustic holograms with shapes such as tweezers,
twisters and cages
that exert forces on particles to levitate and manipulate them.
Credit: Image
courtesy of Asier Marzo, Bruce Drinkwater and Sriram Subramanian © 2015
Sriram Subramanian, Professor of Informatics at the
University of Sussex and co-founder of Ultrahaptics, explained: "In our
device we manipulate objects in mid-air and seemingly defy gravity. We can
individually control dozens of loudspeakers to tell us an optimal solution to
generate an acoustic hologram that can manipulate multiple objects in real-time
without contact.”
The researchers used an array of 64 miniature loudspeakers
(driven at 40Khz with 15Vpp. The whole system consumes 9 Watts of power) to
create high-pitched and high-intensity sound waves to levitate a spherical bead
(of up to 4mm in diameter) made of expanded polystyrene.
The tractor beam works by surrounding the object with
high-intensity sound to create a force field that keeps the objects in place.
By carefully controlling the output of the loudspeakers, the object can be
either held in place, moved or rotated.
Asier Marzo, PhD student and the lead author, said: "It
was an incredible experience the first time we saw the object held in place by
the tractor beam. All my hard work has paid off. It's brilliant."
Bruce Drinkwater, Professor of Ultrasonics in the University
of Bristol's Department of Mechanical Engineering, added: "We all know
that sound waves can have a physical effect. But here we have managed to
control the sound to a degree never previously achieved."
journal reference (Open Access) >>