The world will get considerably more ‘transparent’ if work being done in a lab in Arizona comes to fruition.
Hao Xin, a professor of electrical and computer engineering, has discovered synthetic materials which might one day be used to build microscopes with superlenses and even ‘shields’ which could render military equipment and people invisible to the naked eye.
These metamaterials, which can be made via 3D printing from plastics, metals, and a variety of other substances, look a bit like porous plastic balls, tubes, and tiny copper wire circuit boards, but it’s their specialized geometrical patterns which give them their amazing properties. The metamaterial structures can bend waves of energy in unheard of ways so that they exhibit a property called ‘negative refraction.’
Xin’s work with energy conservation-based theory, full-wave simulation, and experimental measurement shows the 3D printed samples consisting of sub-wavelength building blocks with embedded microwave tunnel diodes exhibit a “band-limited Lorentzian dispersion” and simultaneously, a negative refractive index.
“Our work provides experimental evidence to the assertion that a stable net gain in negative-index gain medium is achievable,” Xin says. “It proposes a potential solution for the critical challenge current metamateiral technology faces in practical applications.”
According to Xin, the work represents a leap forward towards building what he calls “invisibility cloaks.”
The findings have been published in a paper entitled “Microwave Gain Medium With Negative Refractive Index” in the journal Nature Communications.
Imagine a scenario where looking at a person wearing a garment, built with specially-designed refractive properties, would be prevented from seeing the target depending on the refractive index distribution of the pattern.
Xin says sound waves, microwaves, light waves, or seismic waves can be manipulated by metamaterials with negative refraction.
“One of the biggest problems with metamaterials is that they produce energy loss. The waves decay as they pass through the artificial material,” Xin says. “We have designed a metamaterial that retains negative refraction but does not diminish energy.”
The synthetic material constructs do more than prevent energy loss. Xin says they actually cause energy gain, and at least in the case of microwaves, intensify the strength of waves as they passed through this novel material via embedded, battery-powered tunnel diodes and the advantages of micro-nanofabrication techniques.
Funded by the Air Force Office of Scientific Research, the metamaterials research was done with doctoral students in the Millimeter Wave Circuits and Antennas Lab.
One of those doctoral candidates, Adnan Kantemur, says the work provides a chance to study the ideas in practice and lets students actually make metamaterials rather than simply consider them analytically.
The team says the work has implications well beyond the microwave spectrum and could present opportunities in optics, acoustics, and relating to various types of radiation.
While the metamaterials are very much in the testing phase at this point, Xin says he’s confident they wildest applications of the discovery aren’t that far in the future.
“Invisibility cloaks will be a reality in my lifetime,” Xin says.
Do you believe technology like a 3D printed invisibility cloak will be available in your lifetime? Let us know in the 3D Printing Invisibility Cloaks forum thread on 3DPB.com.