3D Aerosol Nanoprinting Helps Researchers Create 3D Metal Nanostructures With 2 Optical Phenomena

3D Aerosol Nanoprinting Helps Researchers Create 3D Metal Nanostructures With 2 Optical Phenomena
(Photo: Wikimedia Commons/FMNLab)

Researchers created three-dimensional metal nanostructures exhibiting two distinct optical phenomena simultaneously using nanoprinting technology.

Nanoprinting Technology Creates 3D Metamaterial With Dual Properties

In a new study, a team of scientists created a metamaterial that can identify the direction and polarization of light using 3D aerosol nanoprinting. The work, led by Ph.D. candidates Younghwan Yang and Hongyoon Kim from the Mechanical Engineering Department at Pohang University of Science and Technology (POSTECH), Professor Junsuk Rho from the Mechanical Engineering, Chemical Engineering, and Electrical Engineering departments, and others, represents a breakthrough in the manipulation of light using metamaterials, which are widely used in applications such as lenses and holograms.

The group employed "3D aerosol nanoprinting technology" to regulate an electric field and airborne metal nanoaerosols to mass-produce three-dimensional nanostructures of any desired shape. Thanks to this approach, they were able to correctly place, construct, and produce 3D metal nanostructures in the shape of "pi (π)" under standard pressure and temperature settings.

During the research, it was shown that the team's three-dimensional metal nanostructures displayed two distinct optical phenomena simultaneously—(1) quasi-bound states in the continuum (q-BIC) and (2)localized surface plasmon resonance (LSPR).

In low-frequency photoelectric resonance (LSPR), light interacts with free electrons on a metallic surface to produce resonances with particular electromagnetic waves. However, a phenomenon known as q-BIC occurs when light becomes trapped in a metal nanostructure.

When the structure is in a well-defined state, like when light is incident vertically, there is little interaction with it. However, in certain situations, such as when light is incident at an angle, a special energy mode forms that gives the impression that the light is connected to the structure.

These dual optical features make high-performance optical sensing possible, preserving resonance while increasing sensor sensitivity. Although these phenomena have been examined separately, it has never been shown that they can coexist in a single structure.

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3D Printing Nano-Sized Metal Structures

Earlier this year, a team of researchers from the Georgia Institute of Technology discovered a faster and cheaper way to print nano-sized metal structures using light. Their technique was 480 times faster and 35 times cheaper than conventional methods.

The process of "nanopatterning," which involves printing metal at the nanoscale, enables the construction of distinctive shapes with intriguing uses. It is essential to advance numerous technologies, including sensors, solar energy conversion, electrical gadgets, and other systems.

High-intensity light sources are widely thought to be necessary for nanoscale printing. However, most research institutes and small enterprises cannot afford this kind of equipment, a femtosecond laser, which can cost up to half a million dollars.

Sourabh Saha, an assistant professor at the George W. Woodruff School of Mechanical Engineering, and Jungho Choi, a Ph.D. student in Saha's lab, developed a novel printing method akin to projection printing by creating a system that translates digital images into optical images for display on a glass surface. The device functions similarly to a digital projector but yields sharper-focused images. Utilizing the special qualities of superluminescent light, they produced images with minimum flaws and excellent focus.

Following approach testing, they discovered that, provided the pictures are sharply focussed, low-intensity light can still be employed for projection-style nanoscale printing. Saha and Choi think that researchers can quickly reproduce their findings by using freely available commercial technology. In contrast to a costly femtosecond laser, Saha and Choi's printer only costs roughly $3,000.