A 160-kilobit memory device that is smaller than a white blood cell was made using interlocked molecules manufactured in the UCLA laboratory of J. Fraser Stoddart, director of the California NanoSystems Institute (CNSI). The research published in Nature describes the fabrication and operation of a memory device. The memory is based on a series of perpendicular, crossing nanowires, similar to a tic-tac-toe board, with 400 bottom wires and another 400 crossing top wires. Sitting at each crossing of the tic-tac-toe structure and serving as the storage element are approximately 300 bistable rotaxane molecules. These molecules may be switched between two different states, and each junction of a crossbar can be addressed individually by controlling the voltages applied to the appropriate top and bottom crossing wires, forming a bit at each nanowire crossing.
The 160-kilobit molecular memory was fabricated at a density of 100,000,000,000 (10**11) bits per square centimeter — "a density predicted for commercial memory devices in approximately 2020," Stoddart said.
This research is the culmination of a long-standing dream that these bistable rotaxane molecules could be used for information storage," said Stoddart, whose areas of expertise include nanoelectronics, mechanically interlocked molecules, molecular machines, molecular nanotechnology, self-assembly processes and molecular recognition, among many other fields of chemistry.
"Our goal was to demonstrate that large-scale, working electronic circuits could be constructed at a density that is well-beyond — 10 to 15 years — where many of the most optimistic projections say is possible."
Caltech chemists and chemical engineers, led by Heath, are the world leaders at making nanowires, according to Stoddart. "Nobody can equal them in terms of the precision with which they carry this research out," he said. The memory device’s top and bottom nanowires, each 16 nanometers wide, were fabricated using a method developed by Heath’s group.
"Molecular switches will lead to other new technologies beyond molecular electronic computers." Stoddart said. "It is too soon to say precisely which ones will be the first to benefit, but they could include areas such as health care, alternative energy and homeland security.