researchers at duke university have used an electrically conductive material that is compatible with standard 3-d printers to print electromagnetic metamaterials, which could revolutionize the design and prototyping of radio frequency (rf) applications like bluetooth, wifi, and communications devices, according to a report on the duke website.
an illustration of how 3-d-printed metamaterial unit cells could be combined like lego blocks to create structures that bend or focus microwave radiation more powerfully than any material found in nature. (duke university)
the article explained, “metamaterials are synthetic materials composed of many individual, engineered devices called cells that together produce properties not found in nature. as an electromagnetic wave moves through the metamaterial, each engineered cell manipulates the wave in a specific way to dictate how the wave behaves as a whole.”
metamaterials can be engineered for various properties, such as bending light backwards for instance, but the current method for creating them has been limited to 2-d circuit boards, which makes creating the metamaterials difficult.
the new process that the duke researchers developed could bring more 3-d metamaterials that have been conceived and theorized into reality. now, the metamaterial can be created in a matter of hours with little cost.
using the correct material for 3-d printing turned out to be the key to the process. rather than using non-conductive plastics or spending millions of dollars to get a metal printer, duke chemists created electrifi, a material that is 100 times more conductive than any other on the market and now being sold by multi3d llc, which is a startup founded by the researchers.
“not only is electrifi conductive enough,” the article continued, “it interacts with radio waves almost as strongly as traditional metamaterials made with pure copper. that small difference is easily made up for by the printed metamaterials’ 3-d geometry -- the results show that the 3-d printed metamaterial cubes interact with electromagnetic waves 14 times better than their 2-d counterparts.”
the article added, “by printing numerous cubes, each tailored to specifically interact with an electromagnetic wave in a certain way, and combining them like lego building blocks, researchers can begin to build new devices. for the devices to work, however, the electromagnetic waves must be roughly the same size as the individual blocks. while this rules out the visible spectrum, infrared and x-rays, it leaves open a wide design space in radio waves and microwaves.”
the research was recently published in applied physics letters. the abstract is as follows:
“this work reports a method for fabricating three-dimensional microwavemetamaterials by fused deposition modeling 3d printing of a highly conductive polymer composite filament. the conductivity of such a filament is shown to be nearly equivalent to that of a perfect conductor for microwave applications.
the expanded degrees-of-freedom made available by 3dmetamaterial designs are demonstrated by designing, fabricating, and testing a 3d-printed unit cell with a broadband permittivity as high as 14.4. the measured and simulated s-parameters agree well with a mean squared error smaller than 0.1.
“the presented method not only allows reliable and convenient fabrication of microwave metamaterials with high conductivity but also opens the door to exploiting the third dimension of the unit cell design space to achieve enhanced electromagnetic properties.”
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