Acoustic tractor beams use the power of sound to hold particles in mid-air, and unlike magnetic levitation, they can grab most solids or liquids. For the first time University of Bristol engineers have shown it is possible to stably trap objects larger than the wavelength of sound in an acoustic tractor beam. This discovery opens the door to the manipulation of drug capsules or micro-surgical implements within the body. Container-less transportation of delicate larger samples is now also a possibility and could lead to levitating humans.
Researchers previously thought that acoustic tractor beams were fundamentally limited to levitating small objects as all the previous attempts to trap particles larger than the wavelength had been unstable, with objects spinning uncontrollably. This is because rotating sound field transfers some of its spinning motion to the objects causing them to orbit faster and faster until they are ejected.
The new approach, published in Physical Review Letters today, uses rapidly fluctuating acoustic vortices, which are similar to tornadoes of sound, made of a twister-like structure with loud sound surrounding a silent core.
(Phys.org)—Researchers have used the pressure of light—also called optical forces or sometimes “tractor beams”—to create a new type of rewritable, dynamic 3D holographic material. Unlike other 3D holographic materials, the new material can be rapidly written and erased many times, and can also store information without using any external energy. The new material has potential applications in 3D holographic displays, large-scale volumetric data storage devices, biosensors, tunable lasers, optical lenses, and metamaterials.
The research was conducted by a multidisciplinary team led by Yunuen Montelongo at Imperial College London and Ali K. Yetisen at Harvard University and MIT. In recent papers published in Nature Communications and Applied Physics Letters, the researchers demonstrated the reversible optical manipulation of nanostructured materials, which they used to fabricate active 3D holograms, lenses, and memory devices.
The key to creating the 3D holographic material with these advantages was to use optical forces to reversibly modify the material’s properties. The optical forces are produced by the interference of two or more laser beams, which creates an optical pressure capable of moving nanoscale structures. So far, optical forces have mainly been used for just one application: optical tweezers, which can hold and move tiny objects and are mostly used in biological applications.
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Holograms (3-D light fields) can be projected from a 2-dimensional surface to control objects. (credit: Asier Marzo, Bruce Drinkwater and Sriram Subramanian)
British researchers have built a working Star-Trek-style “tractor beam” — a device that can attract or repel one object to another from a distance. It uses high-amplitude soundwaves to generate an acoustic hologram that can grasp and move small objects.
The technique, published in an open-access paper in Nature Communications October 27, has a wide range of potential applications, the researchers say. 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.
Researchers from the Universities of Bristol and Sussex, in collaboration with Ultrahaptics, have built the world’s first sonic tractor beam that can lift and move objects using sound waves.
Details of the device, published in Nature Communications, describe how the tractor beam uses high-amplitude sound waves to generate an acoustic hologram that is capable of picking up and moving small objects. The technique comes straight from the pages of a science-fiction novel.
“It was an incredible experience the first time we saw the object held in place by the tractor beam,” said Asier Marzo, PhD student and the lead author of the study.
Levitation and the defiance of gravity is possible. If until now levitation was just a magic act or circus “reality” or, tractor beam technology existed just in sci-fi movies, recently, a team of Japanese researchers have demonstrated the first technology that not only brings the mythology of levitation to life but leap frogs it to create a tractor beam, lifting and moving objects across 3 dimensions using sound alone.
The essence of levitation technology is the countervailing of gravity. By stoping gravity, levitation is possible. It is known that an ultrasound standing wave is capable of suspending small particles at its sound pressure nodes. The acoustic axis of the ultrasound beam in conventional studies was parallel to the gravitational force, and the levitated objects were manipulated along the fixed axis (i.e. one-dimensionally) by controlling the phases or frequencies of bolted Langevin-type transducers.