Flexible circuitry, which can bend but not stretch, has been used by the electronics industry for years. Stretchable electronics offer the potential for new consumer electronic devices such as stretchable displays and wearable electronics as well as implantable biomedical devices that can conform to the body's shape and change shape during movement. See also: Printed circuit board

In a step toward the development of stretchable electronics, also known as elastic electronics, Y. Kim and other researchers at the University of Michigan fabricated multilayered composites, consisting of spherical gold nanoparticles dispersed in an elastomeric polyurethane matrix. Usually if a polymer containing conductive particles is stretched, the material loses its conductive properties as the distance between the particles increases. The composites developed by Kim et al., however, retained their high conductivity even when stretched to more than twice their original length, as the researchers reported in Nature in July 2013. They attributed the persistent conductivity to the formation of pores in the stretched polyurethane through which the gold nanoparticles were able to migrate to form a chainlike network. When the stretched materials were relaxed, the nanoparticles returned to their dispersed state. Repeated stretching of the materials did not decrease their conductivity, even after 10,000 stretches, according to the Nature paper. See also: Composite materials; Electrical conductivity of metals; Gold; Nanoparticles; Nanotechnology; Polyurethane resins