Conductive Ink For Elastic Electronics

To create flexible electronics, researchers often have to make compromises. Boosting a device’s elasticity can mean incorporating materials that sap its conductivity. Nanostructured electronics can provide both flexibility and conductivity, but they tend to be difficult to fabricate and can be incompatible with certain soft substrates, such as textiles. A team of researchers led by Takao Someya of the University of Tokyo has now developed an ink that can be used to print highly conductive and elastic structures such as transistor arrays directly on a variety of materials (Nat. Commun. 2015, DOI: 10.1038/ncomms8461). Key to the ink’s versatility is a well-balanced chemical composition, which includes silver flakes, a fluorinated elastomer, a fluorinated surfactant, and an organic solvent. As the Tokyo team prints the mixture, water and the surfactant begin to separate from the organic solvent, forcing silver flakes to congregate into a conductive network at the ink’s surface. The surfactant also improves the silver’s affinity for the fluorinated polymer, allowing the ink to stay stretchy as it cures.