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Stoddart Lab Heads Nano Work To Build Computer Memory from Molecules
A team of UCLA and California Institute of Technology chemists say they have successfully demonstrated a mega-capacity computer memory device. The work, published in Nature, is based on reconfigurable switches built from interlocking molecules, and were fabricated in the lab of J. Fraser Stoddart, director of the California NanoSystems Institute (CNSI).
J. Fraser Stoddart, director of the California NanoSystems Institute (CNSI), along with UCLA and Caltech researchers, designed and fabricated a molecular memory for computing.
Dr. Stoddart is holds UCLA's Fred Kavli Chair in Nanosystems Sciences and recently was awarded a knighthood by Queen Elizabeth II.
A Closer Look at Memory from Interlocking Molecules
The 160-kilobit molecular memory was fabricated at a density of 100,000,000,000 (1011) bits per square centimeter — "a density predicted for commercial memory devices in approximately 2020," Stoddart said.
The paper published in Jan 25, 2007 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.
A rotaxane is a molecule in which a dumbbell-shaped component, made up of a rod section and terminated by two stoppers, is encircled by a ring. It has the potential to be a molecular abacus. The bistable rotaxanes behave as switches by incorporating two different recognition sites for the ring, and the ring sits preferentially at one of the two, said Stoddart, leader of the UCLA team.
The molecule can act as a switch provided the ring can be induced to move from one site to the other site and then reside there for many minutes. The bistable rotaxane molecules used in the crossbar memory can be switched at very modest voltages from an "off" (low conductivity) to an "on" (high conductivity) state. The stoppers for the rotaxane molecules are designed to allow the molecules to be organized into single-molecule-thick layers, after which they are incorporated into the memory device, Stoddart said.
A Closer Look at Memory from Interlocking Molecules
The 160-kilobit molecular memory was fabricated at a density of 100,000,000,000 (1011) bits per square centimeter — "a density predicted for commercial memory devices in approximately 2020," Stoddart said.
The paper published in Jan 25, 2007 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.
A rotaxane is a molecule in which a dumbbell-shaped component, made up of a rod section and terminated by two stoppers, is encircled by a ring. It has the potential to be a molecular abacus. The bistable rotaxanes behave as switches by incorporating two different recognition sites for the ring, and the ring sits preferentially at one of the two, said Stoddart, leader of the UCLA team.
The molecule can act as a switch provided the ring can be induced to move from one site to the other site and then reside there for many minutes. The bistable rotaxane molecules used in the crossbar memory can be switched at very modest voltages from an "off" (low conductivity) to an "on" (high conductivity) state. The stoppers for the rotaxane molecules are designed to allow the molecules to be organized into single-molecule-thick layers, after which they are incorporated into the memory device, Stoddart said.