Acoustic Standing Waves
Posted: Thu Feb 13, 2014 6:10 pmAcoustophoretic Contactless Elevation, Orbital Transport and Spinning of Matter in Air
in Physical Review Letters, Jan 15, 2014
In a paper in Physical Review Letters, researchers Daniele Foresti and Dimos Poulikakos at the Swiss "Federal Institute of Technology" (ETH) in Zurich, report a technique that uses acoustic waves to lift and spin small droplets, and even put them into tiny orbits
WHAT ?
Stop everything ! Aaarrroooghaaah !! Aaarrroooghaaah !! Crash Dive !
It seems (?) that sound emitted from a transducer that hits a reflecting surface will bounce back to form a standing wave in one dimension; meaning, a water drop placed between the transducer and the reflector will be trapped at one of the nodes.
For spatial control (say what ?), the researchers use three standing-wave traps oriented in different directions; by varying the phase and amplitude of the acoustic waves, Foresti and Poulikakos can trap a spherical droplet, squish it into an oblate shape, and make it spin while suspended in air. They can also swing the droplet around in a controlled orbital motion, without causing violent liquid breakup and atomization.
This technique, which the authors call acoustophoretic manipulation, could enable new kinds of matter transport (wacko science, surely !)
Scientists have been able to use the power of sound to levitate small items — including insects and fish — for decades. But now these researchers have figured out how to move objects around in midair, according to this new study.
Poulikakos’s team performed a number of midair experiments, such as combining water droplets or chemical solutions and even inserting DNA into cells.
They also levitated a wooden toothpick — something that had never been done before — while rotating it and moving it forward and backward.
Sound waves exert pressure when they hit a surface, but the effects are usually too small to notice. But if the intensity is cranked up high enough, sound has the ability to counteract the effects of gravity. (again, wacko science !!)
Poulikakos and his colleagues used levels of about 160 decibels; that’s louder than standing near a rocket launch and is enough to rupture a human eardrum. But they were able to work without ear protection.
They took advantage of the fact that the frequency of sound — the physical property that gives it a pitch — also matters (you don't say ?). Using 24,000 hertz (Hz), a level comparable to a dog whistle, they were unaffected by the noise. The upper range of human hearing is about 20,000 Hz.
Foresti found that balance was the key. Push too hard, and the sound waves will cause a water droplet to explode (yes, this can be some serious sh**t !). Don’t push hard enough, and the droplet will fall and gravity wins.
Poulikakos compares the previous state of acoustic levitation — without the airborne motion control — to a luxury car kept permanently in park. “We could walk around it and enjoy it, but we could not drive it,” he said. “Now we can drive it.”
Physicist Rick Weber of Argonne National Laboratory outside Chicago commended the authors for developing “a highly innovative approach” (haha !) that furthers the capabilities of acoustic levitation.
For now, scientists are able to use acoustic levitation to move only small, lightweight objects. Poulikakos said he will soon release new results that show his team moving heavier and more dense objects, such as steel balls.
So, let's cut the crap, a certain U-Boat Kapitan, 40 years ago, may have been running true torpedoes ?
Now, REALLY ?
Announcement here : http://physics.aps.org/synopsis-for/10. ... 112.024301
Article here : http://www.washingtonpost.com/national/ ... ml?hpid=z2
“Static levitation” (no spatial control) shown here : http://www.youtube.com/watch?v=669AcEBp ... e=youtu.be
in Physical Review Letters, Jan 15, 2014
In a paper in Physical Review Letters, researchers Daniele Foresti and Dimos Poulikakos at the Swiss "Federal Institute of Technology" (ETH) in Zurich, report a technique that uses acoustic waves to lift and spin small droplets, and even put them into tiny orbits
WHAT ?
Stop everything ! Aaarrroooghaaah !! Aaarrroooghaaah !! Crash Dive !
It seems (?) that sound emitted from a transducer that hits a reflecting surface will bounce back to form a standing wave in one dimension; meaning, a water drop placed between the transducer and the reflector will be trapped at one of the nodes.
For spatial control (say what ?), the researchers use three standing-wave traps oriented in different directions; by varying the phase and amplitude of the acoustic waves, Foresti and Poulikakos can trap a spherical droplet, squish it into an oblate shape, and make it spin while suspended in air. They can also swing the droplet around in a controlled orbital motion, without causing violent liquid breakup and atomization.
This technique, which the authors call acoustophoretic manipulation, could enable new kinds of matter transport (wacko science, surely !)
Scientists have been able to use the power of sound to levitate small items — including insects and fish — for decades. But now these researchers have figured out how to move objects around in midair, according to this new study.
Poulikakos’s team performed a number of midair experiments, such as combining water droplets or chemical solutions and even inserting DNA into cells.
They also levitated a wooden toothpick — something that had never been done before — while rotating it and moving it forward and backward.
Sound waves exert pressure when they hit a surface, but the effects are usually too small to notice. But if the intensity is cranked up high enough, sound has the ability to counteract the effects of gravity. (again, wacko science !!)
Poulikakos and his colleagues used levels of about 160 decibels; that’s louder than standing near a rocket launch and is enough to rupture a human eardrum. But they were able to work without ear protection.
They took advantage of the fact that the frequency of sound — the physical property that gives it a pitch — also matters (you don't say ?). Using 24,000 hertz (Hz), a level comparable to a dog whistle, they were unaffected by the noise. The upper range of human hearing is about 20,000 Hz.
Foresti found that balance was the key. Push too hard, and the sound waves will cause a water droplet to explode (yes, this can be some serious sh**t !). Don’t push hard enough, and the droplet will fall and gravity wins.
Poulikakos compares the previous state of acoustic levitation — without the airborne motion control — to a luxury car kept permanently in park. “We could walk around it and enjoy it, but we could not drive it,” he said. “Now we can drive it.”
Physicist Rick Weber of Argonne National Laboratory outside Chicago commended the authors for developing “a highly innovative approach” (haha !) that furthers the capabilities of acoustic levitation.
For now, scientists are able to use acoustic levitation to move only small, lightweight objects. Poulikakos said he will soon release new results that show his team moving heavier and more dense objects, such as steel balls.
So, let's cut the crap, a certain U-Boat Kapitan, 40 years ago, may have been running true torpedoes ?
Now, REALLY ?
Announcement here : http://physics.aps.org/synopsis-for/10. ... 112.024301
Article here : http://www.washingtonpost.com/national/ ... ml?hpid=z2
“Static levitation” (no spatial control) shown here : http://www.youtube.com/watch?v=669AcEBp ... e=youtu.be