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  • Materials that can interact with electromagnetic radiation based on their structure?

  • That's someta.

  • Sorry, had to.

  • But we're talking about metamaterials today!

  • Actually we've talked about them before, and me talking about us talking about them

  • is in fact

  • Meta.

  • Ok I'll stop.

  • But I just figured that since it's been over four years, three sets, and one channel

  • name change ago, we might look at them again and see where the field of metamaterials is

  • now.

  • First off we should get a pretty firm grip on what exactly metamaterials are.

  • Conventional materials interact with electromagnetic radiation like light or radio waves based

  • on the properties of the material.

  • We're used to how glass bends light or how gold reflects light and so on, and in our

  • everyday encounters with these objects we know what to expect because there's nothing

  • special about these materials usually.

  • Unless some crazed engineer replaced them with metamaterials, then things can get pretty

  • unnatural.

  • Take that gold for example.

  • You're used to seeing it all shiny and yellowish and even on the nanoscale that's still true

  • for gold.

  • Unless an engineer were to alter the surface of the gold, making nanoscale structures that

  • changed how the light behaves.

  • Then the gold could be green or red instead of the usual yellowish tint.

  • Nothing about the gold's chemical properties have changed, it's still good old Au, atomic

  • number 79.

  • But the structures on its surface can change how we see it.

  • These special structures take gold from a conventional material to a metamaterial.

  • You might be more familiar with the concept than you realize.

  • One Stanford engineer likens metamaterials to TV antennae of old.

  • To adjust the image quality you would wiggle the antennae around until the geometry interacted

  • with the radio waves better.

  • But the waves carrying TV broadcasts back in the day were centimeters to meters long,

  • so the antennas that interacted with them were relatively big.

  • If you want your material to interact with electromagnetic waves that are microns to

  • nanometers, then the shapes are going to have to be just a fraction of those wavelengths.

  • You can start getting pretty creative with these nanoscale shapes.

  • You could make lenses that don't rely on the material properties of precisely shaped

  • glass to bend light, and instead use metamaterials whose geometry focuses the light the same

  • way, but without the difficulty of shaping a lense, or the weight of bulky glass.

  • With metamaterials I could have glasses lenses that are 100 times thinner than a strand of

  • hair, but still do the same job as these old coke-bottle bottoms of mine.

  • Or you could start mixing materials up to make different structures, or mixing structures

  • up to control electromagnetic waves in any arbitrarily complex way you want.

  • Obviously this has huge implications for a lot of fields that deal with electromagnetic

  • waves.

  • For example there are machines called synchrotrons which use magnets to whip electrons around

  • and around in a circle until they give off X-rays that are then used for various experiments.

  • Synchrotrons are usually the size of buildings, but using 10 million precisely etched shapes

  • in lithium tantalate crystal, researchers were able to coax infrared light in a circle,

  • causing positive and negative charges in the crystal that gave off terahertz radiation,

  • waves that are between infrared and microwaves.

  • The crystal was just half a square millimeter in size, but it was mimicking what you normally

  • need a whole building to do!

  • Magnetic fields can be manipulated with metamaterials too, and researchers at the university of

  • sussex just demonstrated a way to make one magnet connect to another without the other

  • magnetic connecting back.

  • A magnetic diode.This could make wireless power transfer like cell phone charging much

  • more efficient because power would only flow one way.

  • And of course light bending materials open up the possibility of, wait for itinvisibility.

  • But explaining how that works is a whole video of it's own.

  • Just know that with metamaterials, the possibilities are really only limited by how small we can

  • make the structures and your imagination.

  • Pretty meta.

  • If you interested in strange and unique sciences, subscribe to Seeker and check out this video

  • on another way scientists are hacking nature.

  • And fun fact before you go, Meta materials are only possible thanks to the same technology

  • we use to make our nanoscale integrated circuits in today's electronics.

Materials that can interact with electromagnetic radiation based on their structure?

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B1 electromagnetic meta gold magnetic material engineer

These Metamaterials Go Beyond the Properties of Nature

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    林宜悉 posted on 2020/04/04
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