Use different particles, and self-assembly will either form different structures or not occur at all. To make things a bit more complicated, there are two fundamentally different ways of fabricating things from the bottom up.
Nanofabrication techniques and principles
This talk will present the recent developments in nanofabrication techniques. Bottom-up nanofabrication processes typically don't need expensive tooling to create nanoscale structures, and scaling to large volumes is potentially straightforward. Load Next Page. To make things a bit more complicated, there are two fundamentally different ways of fabricating things from the bottom up. First part of the talk covers optical lithography techniques used in micro-nano fabrication. However, the stability of covalent bonds enables the synthesis of almost arbitrary configurations of only up to atoms. This is the vision that proponents or revolutionary nanotechnology put forward: molecular assembly as a factory concept, assembly lines and all, just scaled down to the nano level. Unfortunately, spontaneous self-assembly relies heavily on the particles' characteristics. In another approach the stamp is used mechanically to press the pattern into a thin layer of material. A second disadvantage is that they involve planar techniques, which means that structures are created by the addition and subtraction of patterned layers deposition and etching , so arbitrary three-dimensional objects are difficult to construct. A recent example is IBM's announcement of self-assembling structures in their airgap processors.
In the process he reduced the original block of marble to half its original volume and left the other half as waste. Mechanical printing techniques—nanoscale imprinting, stamping, and molding—have been extended to the surprisingly small dimensions of about 20 to 40 nanometres.
As miniaturization reaches the nanoscale, conventional manufacturing technologies fail because it has not been possible yet to build machinery that assembles nanoscale components into functional devices.
Challenges in nanofabrication
Optical lithography and NIL are the dominant top-down nanomanufacturing methods, although there are a large number of other nanofabrication approaches available. These stamps can be inked and printed as described above, or they can be pressed to the surface and a liquid polymer allowed to flow into the raised regions of the mask by capillary action and cured in place. One-, two-, and three-dimensional structures can be made, and the ability of other nanoscale objects to be functionalized with DNA, combined with the specificity conferred by complementary sequence recognition, means that DNA can connect and organize disparate nanostructures to make relatively complex constructs, including well-controlled nanoparticle crystal lattices, and even active systems. Chemists are using molecules' tendency to self-align to design molecular structures with specific properties. Load Next Page. One bottom-up method is nature's way: self-assembly. For example, the controlled patterning of a molecular monolayer on a surface can be achieved by stamping an ink of thiol functionalized organic molecules directly onto a gold-coated surface molecules that contain a sulfur end group, called a thiol, bond strongly to gold. The challenge for all top-down techniques is that, while they work well at the microscale at millionths of a metre , it becomes increasingly difficult to apply them at nanoscale dimensions. This was last updated in September Continue Reading About nanofabrication. Marble - before and after Michelangelo's top-down approach. This is the vision that proponents or revolutionary nanotechnology put forward: molecular assembly as a factory concept, assembly lines and all, just scaled down to the nano level. First part of the talk covers optical lithography techniques used in micro-nano fabrication. Larger molecules, molecular aggregates, and forms of organized matter more extensive than molecules cannot be synthesized bond-by-bond. Finally, it has been suggested that a so-called biochip might be grown like a plant from a seed; the components would form by a process resembling cell division in living things.
These nanoscale printing techniques offer several advantages beyond the ability to use a wider variety of materials with curved surfaces. Open menu What is nanofabrication?
Until robotic assemblers capable of nanofabrication can be built, self-assembly — together with chemical synthesis — will be the necessary technology to develop for bottom-up fabrication read: "Mind the gap - nanotechnology robotics vision versus lab reality".
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