Pure gold 3D printed in microstructures

The additive metal manufacturing is growing in recent years, with solutions that are widely developed in the international market with a variety of metals: aluminum, stainless steel, titanium, but also precious metals. Traditionally, metal structures can be manufactured by lithographic, casting, laser selective sintering or melting processes. However, these new methods are not yet suitable for 3D printing of metals on a scale whose characteristic size is less than 10 microns, which would be interesting for electronics.

A 3D printing process based on a laser pulse

The method used is more commonly known as “Laser-induced forward transfer” or LIFT. The process consists of emitting an ultra-short laser pulse on a metal film as thin as a nanometer, a pulse that melts the tiny droplet of the metal in question. This droplet is then ejected on its target and solidifies when it lands.

For now, the team explains that this process allows them to create structures from micro droplets of copper and gold. Both metals have similar melting points and in this case copper serves as a mechanical support on which gold can be formed. To test the method, the team will 3D print a propeller of a few microns from droplets of pure gold and copper. Once the structure was completed, the researchers chemically attacked the copper with ferric chlorine to completely eliminate the support. In doing so, they obtain a self-propelled propeller composite in pure gold that could serve as both an electric inductor or a mechanical spring.