Scientists have developed silicon nanowires on a substrate for the first time which are able to stretch to more than double their original length, taking a step closer to incorporating stretchable electronics devices into clothing and other applications.
According to researchers at North Carolina State University, in order to create stretchable electronics you need to put electronics on a stretchable substrate, but electronic materials themselves tend to be rigid and fragile.
“Our idea was to create electronic materials that can be tailored into coils to improve their stretchability without harming the electric functionality of the materials,” says Dr. Yong Zhu,
For the first time Zhu’s team have been able to create silicon nanowire on a rubber substrate that can be stretched by up to 104 percent of its original length.
The research team found that previous experimentation carried out into buckling, wavy shaped materials which stretch like an accordion were not functional due to their propensity to fail at a single point, meaning that the entire structure would also subsequently fail. A coil shape was preferred instead to acheive greater reliability.
“An ideal shape to accommodate large deformation would lead to a uniform strain distribution along the entire length of the structure – a coil spring is one such ideal shape,” Zhu said. “As a result, the wavy materials cannot come close to the coils’ degree of stretchability.”
While other researchers have developed independent nanowire coils, this is the first time that nanowire coils have been directly integrated onto a stretchable substrate.
The team achieved this by placing the rubber substrate under strain, before using ultraviolet radiation and ozone to change its mechanical properties. Finally silicon nanowires were placed on top of the substrate before the strain was released to create coils.
Though the there are some small issues with the materials, it hoped that even greater results will be acheived soon.
“We are working to improve the reliability of the electrical performance when the coils are stretched to the limit of their mechanical stretchability, which is likely well beyond 100 percent, according to our analysis,” said Zhu.