Engineers from North Carolina State University have created stretchable, transparent conductors with a "nano-accordion" design. The conductors could be employed in a wide variety of applications, such as flexible electronics, stretchable displays, or wearable sensors.
Inspired by springs, the technique uses unique geometry to stretch brittle materials. The engineers begin by creating a three-dimensional polymer template on a silicon substrate. The template, shaped like a series of identical, evenly spaced rectangles, is coated with a layer of conducting aluminum-doped zinc oxide. After an elastic polymer is applied to the zinc oxide, the researchers then flip the entire device over and remove the silicon and the template.
A series of symmetrical, zinc oxide ridges on an elastic substrate remains. Because both zinc oxide and the polymer are clear, the structure is transparent. The device is stretchable because the ridges of zinc oxide allow the structure to expand and contract, like the bellows of an accordion.
The 3D templates used in the process are precisely engineered, using nanolithography, because the dimensions of each ridge directly affect the structure’s stretchability. The taller each ridge is, the more stretchable the structure. The structure can be stretched repeatedly without breaking.
