Search: Nanoscience and nanotechnology
Nobel laureate Richard Smalley, the Rice University professor who helped discover buckyballs (buckminsterfullerene, C60, the football (soccer) ball shaped form of carbon, died at the age of 62. Richard Smalley shared the 1996 Nobel Prize in chemistry with Sir Harold Kroto (Sussex) and Robert Curl (also Rice) for the identification of the new form of carbon known as buckminsterfullerene because of its similarity to Buckminster Fuller's geodesic domes. The Richard E. Smalley Institute for Nanoscale Science and Technology continues to champion the efforts of Smalley through research, educational and community programs, corporate partnerships, and government relations.
Workers at The University of Wisconsin-Madison in the USA have managed to release thin membranes of semiconductors from a substrate and transfer them to new surfaces. The freed membranes which are just tens of nanometers thick retain all the properties of silicon in wafer form but the nanomembranes are flexible. By varying the thicknesses of the silicon and silicon-germanium layers composing them, membrane shapes are possible ranging from flat to curved to tubular.
Potential applications include flexible electronic devices, faster transistors, nano-size photonic crystals that steer light, and lightweight sensors for detecting toxins in the environment or biological events in cells.
The scientists made a three-layer nanomembrane composed of a thin silicon-germanium layer sandwiched between two silicon layers of similar thinness. The membrane sat upon a silicon dioxide layer in a silicon-on-insulator substrate. The nanomembranes may be etched away from the oxide layer with hydrofluoric acid.
Although the Wisconsin team grew their nanomembranes on silicon-on-insulator substrates, the method should apply to many substances beyond semiconductors, such as ferroelectric and piezoelectric materials. The key requirement is a layer, like an oxide, that can be removed to free the nanomembranes.1
- 1. Elastically relaxed free-standing strained-silicon nanomembranes,
, Nature Materials, 5/2006, Volume 5, Issue 5, p.388 - 393, (2006)
The Science Blog reports that researchers at Penn State in the USA are developing self-cleaning titania nanotube hydrogen sensors. The hydrogen sensors are titania nanotubes coated with a discontinuous layer of palladium. Hydrogen sensors are widely used in the chemical, petroleum and semiconductor industries. They are also used as diagnostic tools to monitor certain types of bacterial infections.
"The photocatalytic properties of titania nanotubes are so large - a factor of 100 times greater than any other form of titania - that sensor contaminants are efficiently removed with exposure to ultraviolet light, so that the sensors effectively recover or retain their original hydrogen sensitivity in real world application"
"By doping the titania nanotubes with trace amounts of different metals such as tin, gold, silver, copper, niobium and others, a wide variety of chemical sensors can be made. This doping does not alter the photocatalytic properties of the titania nanotubes" says Dr. Craig A. Grimes, associate professor of Electrical Engineering and Materials Science and Engineering.1
- 1. A room-temperature titania-nanotube hydrogen sensor able to self-clean photoactively from environmental contamination,
, Journal of Materials Research, 02/2004, Volume 19, Issue 2, p.628?634, (2004)