The material could find use in flexible electronic displays, sensors, solar cells or even incubators for newborn babies.
“The idea came to me when I was in the hospital with my son, who was in an incubator. I worried about the exposure of the babies to all the electromagnetic radiation in the room. We didn’t want to protect the incubators against the radiation by using metal because then we wouldn’t be able to see the infants,” recalls Atif Shamim, who led the research project. Opaque metals are well known for their electrical conductivity, serving as blocks to electromagnetic radiation, but they are generally not transparent or stretchable.
The research team initially refined the method for making silver nanowires, adapting the previous protocol to make larger quantities of longer nanowires. Those nanowires were then used to create a new ink formulation that resulted in a uniform layer of silver when screen printed onto a flexible substrate. The team found they could then achieve high conductivity with a relatively sparse covering of nanowires, which improved optical transparency.
Following those initial successes, the team then used laser sintering to weld together adjacent nanowires at points of contact. This further improved electrical conductivity while reducing the thickness of the silver layer, which let even more light pass through. The material maintained its electrical performance even after 1000 stretch-release cycles and 1000 bending cycles.
The new material’s performance was then tested by printing the conductive ink in patterns that enabled it to absorb predetermined wavelengths of electromagnetic radiation.
“We believe that this work will benefit the development of future flexible, transparent and stretchable conductive electronics at low cost and at large scale,” said Shamim.
Other potential applications include radar-absorbing coatings to cover the curved surface of fighter planes, rendering them invisible to enemy radar systems.