Researchers take first step towards bendable and fully foldable cell phones, TVs

Scientists have developed a new stretchable and transparent electrical conductor, paving way for fully foldable cell phones and TVs that can be rolled and carried. Researchers developed the gold nanomesh electrodes with "ultra-high stretchability" that provide good electrical conductivity as well as transparency and flexibility. The material also has potential applications for biomedical devices, said Zhifeng Ren, a physicist at the University of Houston and lead author of the research. The researchers reported that gold nanomesh electrodes, produced by the novel grain boundary lithography, increase resistance only slightly, even at a strain of 160 per cent, or after 1,000 cycles at a strain of 50 per cent. The nanomesh, a network of fully interconnected gold nanowires, has good electrical conductivity and transparency, and has "ultrahigh stretchability," researchers said. Unlike silver or copper, gold nanomesh does not easily oxidise, which Ren said causes a sharp drop in electrical conductivity in silver and copper nanowires, they said. Research associates Chuan Fei Guo said the group is the first to create a material that is transparent, stretchable and conductive, as well as the first to use grain boundary lithography in the quest to do so. More importantly it is the first to offer a clear mechanism to produce ultrahigh stretchability, he said. The grain boundary lithography involved a bilayer lift-off metallisation process, which included an indium oxide mask layer and a silicon oxide sacrificial layer and offers good control over the dimensions of the mesh structure. "This is very useful to the field of foldable electronics. It is much more transportable," Guo said. Ren noted that, although gold nanomesh is superior to other materials tested, even it broke and electrical resistance increased when it was stretched. But he said conductivity resumed when it was returned to the original dimensions. The findings were published in the journal Nature Communications. PTI