WEBVTT - Is Printing with Sound the Wave of the Future?

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<v Speaker 1>Welcome to brain Stuff from How Stuff Works pay brain Stuff.

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<v Speaker 1>I'm Lauren Vogelbaum, and I'm here today to tell you

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<v Speaker 1>that Harvard University has announced that its researchers have developed

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<v Speaker 1>a way to print objects using sound as the delivery system,

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<v Speaker 1>called acoustophoretic printing. The method, according to their press release quote,

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<v Speaker 1>could enable the manufacture of many new biopharmaceuticals, cosmetics, and food,

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<v Speaker 1>and expand the possibilities of optical and conductive materials. Let's

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<v Speaker 1>unpack all that printing with liquid such as ink has

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<v Speaker 1>become a way of life thanks to the ink jet

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<v Speaker 1>printing process. But what if instead of ink, you wanted

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<v Speaker 1>to print living cells or other biological materials. What if

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<v Speaker 1>you wanted to print liquid metal with ink jets. The

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<v Speaker 1>ability of a printer to pull a substance out of

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<v Speaker 1>a nozzle grinds to a halt as that substance becomes thicker.

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<v Speaker 1>But now the team of scientists at Harvard has announced

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<v Speaker 1>significant progress in the creation of sound fields that can

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<v Speaker 1>pull viscous substances, much as liquid metal or living cells

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<v Speaker 1>from the nozzle of a printer. It begins with gravity.

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<v Speaker 1>Simple gravity is what causes liquid to drip. How fast

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<v Speaker 1>or how often it drips depends on its viscosity, that's,

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<v Speaker 1>its thickness and its resistance to shearing and tensile stresses. Water,

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<v Speaker 1>for example, is far less viscous than coin syrup. Coin

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<v Speaker 1>syrup is far less viscous than honey. The more viscous

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<v Speaker 1>that a fluid is, the longer it takes for gravity

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<v Speaker 1>to produce a droplet. Printing systems, such as in chip printing,

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<v Speaker 1>typically use a droplet method of transferring a liquid material

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<v Speaker 1>like ink onto a medium like paper. The more viscous

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<v Speaker 1>a material is, however, the more difficult it is to

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<v Speaker 1>manipulate for printing. Daniel Feresti, a research associate in material

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<v Speaker 1>science and mechanical engineering at Harvard, said, our goal was

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<v Speaker 1>to take viscosity out of the picture by developing a

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<v Speaker 1>printing system that is independent from the material properties of

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<v Speaker 1>the fluid. And this is where sound comes in. Foresti

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<v Speaker 1>and his fellow researchers and experimenting with the pressures of

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<v Speaker 1>sound waves on liquids. In order to give gravity a boost,

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<v Speaker 1>They built a sub wavelength acoustic resonator. It's designed to

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<v Speaker 1>produce tightly controlled acoustic fields that effectively increase the relative

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<v Speaker 1>gravity at the printing nozzle. According to the release, the

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<v Speaker 1>researchers have been able to generate pulling forces one times

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<v Speaker 1>the gravitational forces that a printer nozzle would normally experience

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<v Speaker 1>here on Earth. That amount of force also happens to

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<v Speaker 1>be more than four times the gravity that a printer

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<v Speaker 1>nozzle would experience on the Sun. At that point, the

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<v Speaker 1>size of the droplet is determined by the amplitude of

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<v Speaker 1>the sound wave. The higher the amplitude, the smaller the drop. First,

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<v Speaker 1>he said, the idea is to generate an acoustic field

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<v Speaker 1>that literally detaches tiny droplets from the nozzle, a much

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<v Speaker 1>like picking apples from a tree. A wide range of

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<v Speaker 1>materials have been used to test this new printing method,

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<v Speaker 1>including honey stem cell inks, biopolymers, optical resins, and liquid metals.

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<v Speaker 1>Doctor Jennifer Lewis, a professor of biologically inspired engineer RING

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<v Speaker 1>at Harvard, stated, our technology should have immediate impact on

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<v Speaker 1>the pharmaceutical industry. However, we believe that this will become

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<v Speaker 1>an important platform for multiple industries. Today's episode was written

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<v Speaker 1>by Jared W. Alexander and produced by Tyler Clang. To

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<v Speaker 1>find brain Stuff merch hoodie for fall. Maybe check out

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<v Speaker 1>our shop at t public dot com, slash brain stuff,

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<v Speaker 1>and of course, for more on this and lots of

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<v Speaker 1>other topics with a lot of gravity, visit our home planet,

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<v Speaker 1>how stuff works dot com