“Our research shows how 3D printing with some add-on methods such as coating and etching, can truly help make unique optical and millimeter wave devices that previously required multiple discrete and possibly bulky components”Sameer Sonkusale
New approaches to 3D printing are allowing for the production of a greater range of shapes and patterns of metamaterials at increasingly small scales. Now, scientists at Tufts Universityhave developed 3D printed metamaterials with unique microwave or optical properties that improve upon what is possible with standard optical or electronic materials.They demonstrated a hybrid fabrication method based on 3D printing, metal coating and etching with complex geometries and novel functionalities for wavelengths in the microwave range that could find uses in applications including sensors in medical diagnoses, antennas in telecommunications or detectors in imaging.
As described in the journal Microsystems & Nanoengineering[Sadeqi et al. Microsyst. Nanoeng(2019) DOI: 10.1038/s41378-019-0053-6], the fabrication shows the potential of 3D printing to increase the possibilities in geometric designs and material composites for devices with novel optical properties. One device was inspired by the compound eye of a moth to produce a hemispherical device that absorbs electromagnetic signals from any direction at specific wavelengths, while another was an array of small mushroom-shaped structures holding a patterned metal resonator, which permits microwaves of specific frequencies to be absorbed depending on the chosen geometry and their spacing.
The work could open up 3D printing in photonics, millimeter-wave and optical science and engineering, and the new class of metamaterial-embedded geometrical optical devices can also enable realization of functionalities that reduce the cost, size and weight of equipment such as spectrometers. As corresponding author Sameer Sonkusale said “It's possible that we could use these materials to reduce the size of spectrometers and other optical measuring devices so they can be designed for portable field study”.
Combining optical/electronic patterning with 3D fabrication of the underlying substrate were described by the team as “metamaterials embedded with geometric optics”, or MEGOs. Other shapes, sizes, and orientations of patterned 3D printing could be developed to produce MEGOs that absorb, enhance, reflect or bend waves that are impossible with conventional fabrication. As lead author Aydin Sadeqi said “There is much more we can do with the current technology, and a vast potential as 3D printing inevitably evolves”.
Consolidating a number of devices into one device also reduces the costs involved, as well as adding functionality. As Sameer Sonkusale told Materials Today, “Our research shows how 3D printing with some add-on methods such as coating and etching, can truly help make unique optical and millimeter wave devices that previously required multiple discrete and possibly bulky components”.
The team are currently working on more novel devices that can be fabricated using 3D printing, avoiding the costly steps of photolithography. Such devices will operate in the upper microwave and terahertz frequency regime, the latter being useful for new work in imaging, spectroscopy and communication. They are also interested in innovating new multifunctional MEGO device concepts using this new approach.
Multifunctional devices merging geometrical optics and metamaterials