Cellphones, laptops, tablets, and many other electronics rely on their internal metallic circuits to process information at high speed. Current metal fabrication techniques tend to make these circuits by getting a thin rain of liquid metal drops to pass through a stencil mask in the shape of a circuit. But this technique generates metallic circuits with rough surfaces, causing electronic devices to heat up and drain their batteries faster.
Future ultrafast devices also will require much smaller metal components, which calls for a higher resolution to make them at these nanoscale sizes. This requires molds with higher and higher definition, until they reach the nanoscale size. This so-called “formability limit” hampers the ability to manufacture materials with nanoscale resolution at high speed.
Researchers have addressed both of these issues — roughness and low resolution — with a large-scale fabrication method that enables the forming of smooth metallic circuits at the nanoscale using conventional carbon dioxide lasers, which are already common for industrial cutting and engraving. The manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process combines tools already used in industry for manufacturing metals on a large scale, but uses the speed and precision of roll-to-roll newspaper printing to remove a couple of fabrication barriers in making electronics faster than they are today. The fabrication method, called roll-to-roll laser-induced superplasticity, uses a rolling stamp like the ones used to print newspapers at high speed. The technique can induce, for a brief period of time, “superelastic” behavior to different metals by applying high-energy laser shots, enabling the metal to flow into the nanoscale features of the rolling stamp, circumventing the formability limit.
This roll-to-roll fabrication of devices could enable the creation of touchscreens covered with nanostructures capable of interacting with light and generating 3D images, as well as the cost-effective fabrication of more sensitive biosensors.