The Background To Molecular Electronics Building electronics at the molecular level requires new materials and new manufacturing concepts. Conventional micro-fabrication techniques are reaching the limits of their capabilities, while fabrication costs and complexity continue to grow. Physical limitations of silicon-based devices will inhibit continued innovation in IT, communications, and electronics. The rising cost of these materials and environmentally sensitive and expensive processes needed for fabrication will continue to pressure the electronics industry until solutions are found. To overcome these limits, a wide variety of alternative computer architectures have been suggested including ones based on DNA, optical circuitry, and quantum mechanical phenomena. One of the most promising areas is the use of individual molecules as active electronic devices. Molecular Electronics In The Future Molecular Electronics seeks to replace current electronics technology by implementing one or a few molecules to function as switches, connections, and other logic devices. Molecules assemble themselves into devices that go beyond the limitations of rigid silicon-based solutions and create conductive and strong interconnects using environmentally sensitive fabrication techniques. Molecular electronics spans several broad fields and it overlaps with several more covering everything from the development of optical discs based on films of bistable biomolecules to the conceptual design of computers based on molecular wires and switches. The Future Of Molecular Computing Molecular computing could replace silicon-based computing by the end of the decade. Chemists at the University of California have created a molecular switch that can be turned on and off hundreds of times, just a year after creating a switch that could be switched only once. The development of molecular random access memory (RAM) still poses an obstacle to the viability of molecular computing, but this latest step brings molecular RAM within reach. The UCLA researchers are working in collaboration with HP researchers to create molecular computers that can learn, improving the more they are used. Molecular switches are vital to developing this kind of computer. The latest molecular switches were created using unique molecules, called catenanes, which consist of two tiny mechanically interlocked rings, each ring composed of atoms linked in a circle. The switching motion, which can be induced by taking away and giving back an electron, is the molecular basis for the present device. Moving in a coherent motion, these molecules have the ability to recognize one another and line up in an efficient manner. The catenaes are an improvement over rotaxane molecules. Rotaxanes were in a solution state and were much more incoherent. The Background To Quantum Dots Quantum Dots are crystalline particles of semiconductor materials which, being smaller than the wavelength of visible light cannot be seen under normal conditions. They can impart new properties while remaining invisible themselves. Quantum Dots luminesce under ultraviolet light, with the size of the dots controlling its colour. Quantum Dots And Their Properties Quantum Dots will fluoresce or stay lit much longer then dyes conventionally used for tagging cells. They are showing promise in early warning test kits for disease. Dots are tagged to proteins and their glow enables the identification of specific proteins or DNA making it possible to diagnose various diseases. How much protein is on each cell can be ascertained by the amount of light transmitted in a particular colour. A change in the concentration of proteins on each cell can be an early indication of cancer. Other Unique Properties Of Quantum Dots Quantum Dots also have other unique electronic properties. The size and shape of their structures and therefore the number of electrons they contain, can be precisely controlled; a quantum dot can have anything from a single electron to a collection of several thousands electrons. | 
