Metal Printing Makes Stretchable Electronics
January 8, 2018
from North Carolina State University have developed a new technique for
directly printing metal circuits, creating flexible, stretchable
electronics. The technique can use multiple metals and substrates and is
compatible with existing manufacturing systems that employ direct
“Flexible electronics hold promise for use in many fields, but there are
significant manufacturing costs involved – which poses a challenge in
making them practical for commercial use,” says Jingyan Dong,
corresponding author of a paper on the work and an associate professor
in NC State’s Edward P. Fitts Department of Industrial & Systems
This prototype demonstrates the
potential of the new technique for printing flexible, stretchable
“Our approach should reduce cost and offer an efficient means of
producing circuits with high resolution, making them viable for
integrating into commercial devices,” Dong says.
The technique uses existing electrohydrodynamic printing technology,
which is already used in many manufacturing processes that use
functional inks. But instead of ink, Dong’s team uses molten metal
alloys with melting points as low as 60 degrees Celsius. The researchers
have demonstrated their technique using three different alloys, printing
on four different substrates: one glass, one paper and two stretchable
“This is direct printing,” Dong says. “There is no mask, no etching and
no molds, making the process much more straightforward.”
The researchers tested the resilience of the circuits on a polymer
substrate and found that the circuit’s conductivity was unaffected even
after being bent 1,000 times. The circuits were still electrically
stable even when stretched to 70 percent of tensile strain.
The researchers also found that the circuits are capable of “healing”
themselves if they are broken by being bent or stretched too far.
of the low melting point, you can simply heat the affected area up to
around 70 degrees Celsius and the metal flows back together, repairing
the relevant damage,” Dong says.
The researchers demonstrated the functionality of the printing technique
by creating a high-density touch sensor, fitting a 400-pixel array into
one square centimeter.
“We’ve demonstrated the resilience and functionality of our approach,
and we’re open to working with the industry sector to implement the
technique in manufacturing wearable sensors or other electronic
devices,” Dong says.
The paper, “Electrohydrodynamic (EHD) Printing of Molten Metal Ink for
Flexible and Stretchable Conductor with Self-Healing Capability,” is
published in the journal Advanced Materials Technologies. Lead author of
the paper is Yiwei Han, a Ph.D. student at NC State. The work was done
with support from the National Science Foundation under grant numbers
CMMI-1333775 and CBET-1344618.