Blowing bubbles for nanoelectronics

The key to realizing many of the proposed electronics applications of nanomaterials may be as simple as blowing bubbles. Blown-film extrusion—the bubble-blowing process used to make garbage bags—has now been used to create large-area films of uniformly aligned inorganic nanowires and carbon nanotubes (Nat. Nanotechnol., DOI: 10.1038/nnano.2007.150). The films can then be transferred to large crystalline wafers and flexible plastic substrates for use in electronic devices. Because nanowires and nanotubes tend to tangle, these materials have proven difficult to process for electronics applications, where uniformity is preferred. Guihua Yu and Charles M. Lieber of Harvard University and Anyuan Cao of the University of Hawaii at Manoa, Honolulu, found that when they used bubble-based processing on a homogeneous epoxy suspension of nanowires or nanotubes, they could control both the density and alignment of the nanomaterials in the resulting films. The process "represents one of the most critical advances necessary" for realizing many applications of nanomaterials in electronics, according to the team.