Saturday, October 12, 2019

Molecular Switches :: essays research papers fc

We live in the technology age. Nearly everyone in America has a computer or at least access to one. How big are the computers you are used to? Most are about 7" by 17" by 17". That's a lot of space. These cumbersome units will soon be replaced by something smaller. Much smaller, we're talking about computers based on lone molecules. As far off as this sounds, scientists are already making significant inraods into researching the feasability of this. Our present technology is composed of solid-state microelectronics based upon semiconductors. In the past few years, scientists have made momentus discoveries. These advances were in molecular scale electronics, which is based on the idea that molecules can be made into transistors, diodes, conductors, and other components of microcircuits. (Scientific American) Last July, researchers from Hewlitt-Packard and the University of California at Los Angeles announced that they had made an electronic switch of a layer of several million molecules and rotaxane. "Rotaxane is a pseudorotaxane. A pseudorotaxane is a compound consisting of cyclic moles threaded by a linear molecule. It also has no covalant interaction. In rotaxane, there are bulky blocking groups at each end of the threaded molecule." (Scientific American) The researchers linked many of these switches and came up with a rudimentary AND gate. An AND gate is a device which preforms a basic logic function. As much of an achievement as this was, it was only a baby step. This million-moleculed switch was too large to be useful and could only be used once. In 1999, researchers at Yale University created molecular memory out of just one molecule. This is thought to be the "last step down in size" of technology because smaller units are not economical. The memory was created through a process called "self-assembly". "Self-assembly" is where computer engineers "grow" parts and interconnections with chemicals. (Physics News Update, 1999) This single molecule memory is better than the conventional silicon memory (DRAM) because the it live around one million times longer. ' "With the single molecule memory, all a general-purpose ultimate molecular computer needs now is a reversible single molecule switch," says Reed (the head researcher of the team.) "I anticipate we will see a demonstration of one very soon." ' (Yale, 1999) Reed was correct. Within a year, Cees Dekker and his colleagues at Delft University of Technology in the Netherlands had produced the first single molecule transistor.

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