Bendable and stretchable electrodes are important components for wearable or foldable electronics. Stretchable electrodes have been developed using conductive materials in wrinkled or wavy structures. However, most of these electrodes can only be stretched in one direction.

Jing Kong, Massachusetts Institute of Technology (MIT), Cambridge, USA, Ho Seok Park, Sungkyunkwan University, Republic of Korea, and colleagues have developed transparent electrodes that are omnidirectionally stretchable. The team synthesized a multilayer graphene electrode that has a concentric circular wavy structure, similar to a Fresnel lens (pictured). To prepare the electrodes, the team patterned a copper foil with a Fresnel lens as a mold. Then they used chemical vapor deposition (CVD) to grow multilayered graphene on the foil. The graphene was coated with an elastomeric polydimethylsiloxane (PDMS) film, and the copper base etched away to release the electrode.

The electrodes have high optical transparency (up to 87 %), low sheet resistance, and retain their electrical performances under mechanical stress such as bending, stretching, and folding. According to the researchers, this approach could be useful for a range of applications involving stretchable devices and wearable integrated systems.

• Omnidirectionally Stretchable and Transparent Graphene Electrodes,
  Jin-Yong Hong, Wook Kim, Dukhyun Choi, Jing Kong, Ho Seok Park,
  ACS Nano 2016.
  DOI: 10.1021/acsnano.6b04493