Acoustic levitation
Encyclopedia
Acoustic levitation is a method for suspending matter in a medium by using acoustic radiation pressure
from intense sound
waves in the medium. Acoustic levitation
is possible because of the non-linear effects of intense sound waves.
Some methods can levitate objects without creating sound heard by the human ear such as the one demonstrated at Otsuka Lab, while others produce some audible sound. There are many ways of creating this effect, from creating a wave underneath the object and reflecting it back to its source, to using an acrylic glass
tank to create a large acoustic field.
Acoustic levitation is usually used for containerless processing which has become more important of late due to the small size and resistance of microchips and other such things in industry. Containerless processing may also be used for applications requiring very-high-purity materials or chemical reactions too rigorous to happen in a container. This method is harder to control than other methods of containerless processing such as electromagnetic levitation but has the advantage of being able to levitate nonconducting
materials.
There is no known theoretical limit to what acoustic levitation can lift given enough vibratory sound, but in practice current technology limits the amount that can be lifted by this force to at most a few kilograms. Acoustic levitators are used mostly in industry and for researchers of anti-gravity
effects such as NASA
; however some are commercially available to the public.
Acoustic radiation pressure
Acoustic radiation pressure is the apparent pressure difference between the average pressure at a surface moving with the sound displacements and the pressure that would have existed in the fluid of same mean density at rest...
from intense sound
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
waves in the medium. Acoustic levitation
Levitation
Levitation is the process by which an object is suspended by a physical force against gravity, in a stable position without solid physical contact...
is possible because of the non-linear effects of intense sound waves.
Some methods can levitate objects without creating sound heard by the human ear such as the one demonstrated at Otsuka Lab, while others produce some audible sound. There are many ways of creating this effect, from creating a wave underneath the object and reflecting it back to its source, to using an acrylic glass
Acrylic glass
Poly is a transparent thermoplastic, often used as a light or shatter-resistant alternative to glass. It is sometimes called acrylic glass. Chemically, it is the synthetic polymer of methyl methacrylate...
tank to create a large acoustic field.
Acoustic levitation is usually used for containerless processing which has become more important of late due to the small size and resistance of microchips and other such things in industry. Containerless processing may also be used for applications requiring very-high-purity materials or chemical reactions too rigorous to happen in a container. This method is harder to control than other methods of containerless processing such as electromagnetic levitation but has the advantage of being able to levitate nonconducting
Electrical conductor
In physics and electrical engineering, a conductor is a material which contains movable electric charges. In metallic conductors such as copper or aluminum, the movable charged particles are electrons...
materials.
There is no known theoretical limit to what acoustic levitation can lift given enough vibratory sound, but in practice current technology limits the amount that can be lifted by this force to at most a few kilograms. Acoustic levitators are used mostly in industry and for researchers of anti-gravity
Anti-gravity
Anti-gravity is the idea of creating a place or object that is free from the force of gravity. It does not refer to the lack of weight under gravity experienced in free fall or orbit, or to balancing the force of gravity with some other force, such as electromagnetism or aerodynamic lift...
effects such as NASA
NASA
The National Aeronautics and Space Administration is the agency of the United States government that is responsible for the nation's civilian space program and for aeronautics and aerospace research...
; however some are commercially available to the public.
See also
- Electrostatic levitationElectrostatic levitationElectrostatic levitation is the process of using an electric field to levitate a charged object and counteract the effects of gravity. It was used, for instance, in Robert Millikan's oil drop experiment and is used to suspend the gyroscopes in Gravity Probe B during launch.Due to Earnshaw's...
- Magnetic levitationMagnetic levitationMagnetic levitation, maglev, or magnetic suspension is a method by which an object is suspended with no support other than magnetic fields...
- Optical levitationOptical levitationOptical levitation is a method developed by Arthur Ashkin whereby a material is levitated against the downward force of gravity by an upward force stemming from photon momentum transfer...
- Aerodynamic levitationAerodynamic levitationAerodynamic levitation is the use of gas pressure to levitate materials so that they are no longer in physical contact with any container. In scientific experiments this removes contamination and nucleation issues associated with physical contact with a container.-Overview:The term aerodynamic...
- Radiation pressureRadiation pressureRadiation pressure is the pressure exerted upon any surface exposed to electromagnetic radiation. If absorbed, the pressure is the power flux density divided by the speed of light...
- BuoyancyBuoyancyIn physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...