University of Illinois team creates graphene patterning technique

A team at the University of Illinois at Urbana-Champaign has developed a one-step, facile method to pattern graphene.

Researchers have announced that graphene, a two-dimensional carbon allotrope, can be patterned by using stencil mask and oxygen plasma reactive-ion etching, and subsequent polymer-free direct transfer to flexible substrates.

This is a schematic illustration of the one-step polymer-free approach to fabricate patterned graphene on a flexible substrate. A stencil mask is designed by computer-aided design software and fabricated by a laser cutter. The fabricated mask is aligned on the as-grown CVD graphene on a Cu foil, and the exposed graphene region is removed by oxygen plasma. The patterned graphene is laminated onto a flexible substrate, followed by etching of the copper foil. (Photo: University of Illinois)

Graphene has been the subject of scientific interest due to its highly preferable characteristics. The material provides a base material for next generation bioelectrical, electromechanical, optoelectronic, and thermal management applications.

“In conjunction with the recent evolution of additive and subtractive manufacturing techniques such as 3D printing and computer numerical control milling, we developed a simple and scalable graphene patterning technique using a stencil mask fabricated via a laser cutter,” stated Keong Yong, a graduate student and first author of the paper, “Rapid Stencil Mask Fabrication Enabled One-Step Polymer-Free Graphene Patterning and Direct Transfer for Flexible Graphene Devices appearing in Scientific Reports.

Yong explains that the team’s approach to patterning graphene is based on a shadow mask technique that has been employed for contact metal deposition. The stencil masks are easily and rapidly manufactured for iterative rapid prototyping. However, they are also reusable, enabling cost-effective pattern replication.

“Since our approach involves neither a polymeric transfer layer nor organic solvents, we are able to obtain contamination-free graphene patterns directly on various flexible substrates,” Yong explains

This approach demonstrates a new possibility to overcome limitations imposed by existing post-synthesis processes to achieve graphene micro-patterning, explains SungWoo Nam, an assistant professor of mechanical science and engineering at Illinois.

Yong envisions this facile approach to graphene patterning sets forth transformative changes in “do It yourself” (DIY) graphene-based device development for broad applications including flexible circuits/devices and wearable electronics.

“This method allows rapid design iterations and pattern replications, and the polymer-free patterning technique promotes graphene of cleaner quality than other fabrication techniques,” Nam said. “We have shown that graphene can be patterned into varying geometrical shapes and sizes, and we have explored various substrates for the direct transfer of the patterned graphene.”