In the never-ending search for faster, better ways to create the components needed for modern and future electronics, a new manufacturing technique using a process similar to newspaper printing shows promise to form smoother and more flexible metals for use in making ultrafast electronic devices.
Developed by a team of engineers and researchers at Purdue University, the low-cost process combines tools that are already used in the industry for the large-scale manufacturing of metals--but introduces the use of high-speed and high-precision roll-to-roll newspaper printing processes. This technique removes several fabrication barriers to making electronics faster than we're able to make them today.
Cellphones, laptops, tablets and other modern electronics rely on their internal metallic circuits to process information at high speed. The existing metal fabrication techniques used in manufacturing tend to make these circuits by passing a thin rain of liquid metal drops through a stencil mask in the shape of a circuit, kind of like spraying graffiti on a wall.
"Unfortunately, this fabrication technique generates metallic circuits with rough surfaces, causing our electronic devices to heat up and drain their batteries faster," said Ramses Martinez, assistant professor of industrial engineering and biomedical engineering at Purdue.
The ultrafast and highly complex electronic devices of the future will also require much smaller metal components, which calls for a higher resolution to make them at these nanoscale sizes.
"Forming metals with increasingly smaller shapes requires molds with higher and higher definition, until you reach the nanoscale size," Martinez said. "Adding the latest advances in nanotechnology requires us to pattern metals in sizes that are even smaller than the grains they are made of. It's like making a sand castle smaller than a grain of sand."
This is the so-called "formability limit," which hampers the ability to manufacture materials with nanoscale resolution at high speed.
Purdue's research team has addressed both the issue of roughness and that of low resolution with a new 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.
"Printing tiny metal components like newspapers makes them much smoother. This allows an electric current to travel better with less risk of overheating," Martinez said.
The fabrication method, called roll-to-roll laser-induced superplasticity, uses a rolling stamp like the ones used in the high-speed printing of newspapers. The technique can induce, for a brief period of time, "superelastic" behavior in different metals by applying high-energy laser shots, which enables the metal to flow into the nanoscale features of the rolling stamp – circumventing the formability limit.
"In the future, the roll-to-roll fabrication of devices using our technique could enable the creation of touch screens covered with nanostructures capable of interacting with light and generating 3D images, as well as the cost-effective fabrication of more sensitive biosensors," Martinez said.
To learn more about flexible and nanoscale technology, check out these stories: