New Nanoscale 3D Printing Techniques Developed

Above: SEM images and the corresponding full EDX mapping results of the zodiacs patterned on pre-shrunk hydrogels. (Note that the mappings of all the rare earth elements are merged into one image (RE) due to their low ratios in the NPs; and the abundant oxygen at the background of TiO2 and Fe3O4 patterns, and the Na at the background of NaYREF4 can be partially attributed to the hydrogel substrate); Scale bars are 1 μm. Below: Fabrication of large-scale woodpile structures: (A) 12-layer woodpile structure of florescent polystyrene (top view, stitched from 16 sub-images due to the limited microscope field of view); (B) zoomed-in view of (A), where the inset shows a 3D fluorescent image of the structural details in the selected area; (C) cuboid woodpile structure of florescent protein; (D) O-shaped 3D woodpile structure of CdSe. Courtesy of Chinese University of Hong Kong

A team at The Chinese University, Hong Kong (CUHK), working with Carnegie Mellon University, has developed a new approach to 3D printing, allowing ultra-fine (Nano) products to be produced with improved resolution, rate of production, and lower manufacturing costs in a variety of materials.

According to a press release by CUHK, a multi-disciplined research team headed by Professor Chen Shih-Chi of CUHK in conjunction with Professor Zhao Yongxin from Carnegie Mellon University, in Pittsburgh, Pennsylvania, has developed a 3D nanofabrication platform that, for the first time realizes multi-material fabrication, meaning it can use a great variety of materials, including metals, alloys, semiconductors, polymers, ceramics and biomaterials at a record-setting resolution of 20 nanometers, and a light patterning speed of 300 cubic millimeter/hour, three orders of magnitude faster than conventional serial fabrication systems that are currently used in the commercial world. The achievement has recently been published in the journal Science.

Multi-material 3D fabrication at the nanoscale level is considered a key enabler for developing new technologies, including photonic, electronic, and biomedical devices.

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The team developed a general strategy for fabricating arbitrary 3D nanostructures with a library of materials, including metals, metal alloys, 2D materials, oxides, diamonds, upconversion materials, semiconductors, polymers, biomaterials, molecular crystals, and inks.

In their research, hydrogels patterned by femtosecond light sheets were used as templates that allow the direct assembly of materials to form designed nanostructures. By fine-tuning the exposure strategy, the features of the patterned gel, and the kinetic effects, the team produced 2D and 3D structures of 20- to 200-nanometre resolution. They fabricated nanodevices, including encrypted optical storage, diffractive optical elements, and microelectrodes, to showcase the precision and the designed functions.

Chen explained in the press release that the true importance of this work lies in the fact that the method simultaneously achieved all key metrics in manufacturing: resolution, fabrication rate, and cost. “This means our new method can not only be used to make micro and nanodevices, not previously possible but can make them at high throughput and low cost for practical applications in photonics, health, automobiles, and even aerospace.”

In the future, the researchers aim to build functional nanodevices with multiple materials, like nanocircuits, nanobiosensors, light-emitting diodes, and lasers, for different applications.