3D printing has completely changed the manufacturing process in the fields of electronics, optics, energy, robotics, bioengineering, and sensing.
The reduced size of 3D printing technology will make it possible to utilize the characteristics of microstructures and nanostructures. However, the existing metal 3D nano-printing technology requires polymer-metal mixtures, metal salts or rheological inks, which limits the choice of materials and the purity of the final structure.
Aerosol lithography, although previously used to assemble high-purity 3D metal nanostructure arrays on pre-molded substrates, the geometric shapes that can be printed are very limited.
The researchers introduced a technique for direct 3D printing of metal nanostructure arrays. The metal nanostructures have flexible geometric shapes and feature sizes, up to hundreds of nanometers, and can use a wide range of materials.
This printing process takes place in a dry air environment and does not require polymers or inks. Instead, ions and charged aerosol particles are directed to a dielectric mask containing a set of holes that float on a biased silicon substrate.
These ions gather around each hole, creating electrostatic lenses, focusing the charged aerosol particles into nano-sized jets. These jets are guided by polymeric electric field lines formed under a mask with holes, which act like a nozzle of a traditional 3D printer, enabling aerosol particles to be 3D printed on a silicon substrate.
By moving the substrate during the printing process, they successfully printed various 3D structures, including spirals, overhanging nanotubes, ring structures, and letters. In the experiment, the width of the printable structure is much smaller than the size of the hole, and the structure of the object to be printed can be manipulated by translating the nano-stage in 3D space.
In addition, in order to demonstrate the potential applications of this technology, the researchers printed a set of vertical split ring resonator structures that interact with magnetic fields. The combination of tip-directed growth and surface writing produces a vertical SRR array with a spacing of 9.2 μm. The excitation of the vertical SRR, called magnetic resonance, was confirmed by reflectance spectroscopy measurements and simulations.
Combined with other 3D printing methods, the researchers hope that 3D-nano-printing technology can make substantial progress in nano-manufacturing. Recently, their research results were published in the journal Nature with the title "Three-dimensional nanoprinting via charged aerosol jets".