In ‘High Resolution, reconfigurable printing of liquid metals with three-dimensional structures’ authors Young-Geun Park, Hyeon Seok An, Ju-Young Kim, and Jang-Ung Park explore a new technique outside the usual realm of metal 3D printing. With liquid metal 3D printing, the authors can create ‘stretchable’ 3D integrations formed into ‘diverse 3D structures.’ As an example in this study, they create a reconfigurable antenna.
Deformity in devices is a focus here, centered around applications in ‘freeform electronics’ like:
- Stretchable electronics
- Wearable electronics
- Soft actuators
Previously, there have been challenges in finding suitable materials for such devices that require movable parts that are also a comfortable fit for the consumer, or easy to manipulate as functional objects. The authors point out that brittleness is often an issue, although conductive materials have been developed like wavy metals, metallic networks, and a variety of composites. While promising, such methods are not always scalable to 3D printing, and resolution may be an issue.
“While filament-based direct ink writing methods using inks of metal nanoparticles (e.g., Ag or Cu) have shown some feasibility for high resolution printing, they require additional thermal annealing or a drying process to form conductive pathways, which can cause damage to soft, tissue-like substrates. In addition, these printed and thermally annealed patterns of metals are relatively rigid and stiff; hence, repetitive device deformations can lead to cracking or failure in these metallic electrodes.”
The researchers discuss liquid metals like eutectic gallium-indium alloy (EGaIn) and gallium-indium-tin alloy (Galinstan), both stretchable materials that also exhibit low levels of toxicity and very little volatility. In comparison to solid metals, they also demonstrate excellent conductivity. While microfluidics or lithography can be used for patterning the liquid metals, their structures are limited to the 2D realm. Using a fine nozzle to print liquid metal under ambient conditions, the authors are able to create high-resolution structures. The use of narrow metallic filament allows for free-standing structures to be fabricated from liquid metal; in fact, they can even be lifted by the nozzle and moved.
The high-resolution antennas were 3D printed as samples for the research, using a nozzle mounted to a syringe, and a substrate placed on the five-axis stage. The team also created free-standing structures of electrodes, allowing for minimization of interconnections—and ‘an aim toward higher integrations for miniaturized devices.’
“We believe that this high-resolution 3D reconfiguration method offers a promising strategy as an additive process that can be combined with conventional fabrication techniques for highly integrated and stretchable devices, indicating substantial promise for use in next-generation electronics,” stated the researchers.
While many industrial users are enjoying benefits such as the ability to build complex geometries that are strong yet lightweight, metal is being explored as the strongest medium for 3D printing, whether in creating porous metallic biomaterials, automated sheet metal production, or patented metals with high carbide content. What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.