Question

1. what is the difference between top down and bottom up nano-manufacturing and explain here with examples of each.

Answer 1

Nanotechnology is designing, developing at nanometer scale. The dealing object size should be less than hundred nanometers at least in one dimension to nanotechnology.

There are two design approaches in nanotechnology known as top-down and bottom-up.

Top-down Approach

In top-down approach, nano-scale objects are made by processing larger objects in size. Integrated circuit fabrication is an example for top down nanotechnology.

Now it has been grown to the level of fabricating nano electromechanical systems (NEMS) where tiny mechanical components such as levers, springs and fluid channels along with electronic circuits are embedded to a tiny chip. The starting materials in these fabrications are relatively large structures such as silicon crystals.

Bottom –up Approach

Bottom-up approach in nanotechnology is making larger nanostructures from smaller building blocks such as atoms and molecules. Self assembly in which desired nano structures are self assembled without any external manipulation. When the object size is getting smaller in nanofabrication, bottom-up approach is an increasingly important complement to top-down techniques.

Bottom-up approach nanotechnology can be found from nature, where biological systems have exploited chemical forces to create structures for cells needed for life. Scientists and engineers perform research to imitate this quality of nature to produce small clusters of specific atoms, which can then self assemble into more complex structures. Manufacturing of carbon nanotubes using metal catalyzed polymerization method is a good example for bottom-up approach nanotechnology.