A bottom-up approach (self-assembly processes) is a term used to describe one of two ways to fabricate Nanometre size elements of integrated electronic circuits. It is building Nanostructures from atoms and molecules by precise positioning on a substrate. Hence a single device level is constructed upward, mechanical processes such as self-assembling, self-organisation and atomic engineering.
The bottom-up approach has the potential to go far beyond the limits of top-down technology. Biologically-inspired assembly/molecular manufacturing is one of the most challenging nanomanufacturing techniques. It is ideal to think of utilising the many directed self-assembly techniques inherent in nature to make a wide range of hierarchical structures. There are many barriers to mimicking nature including precision synthesis or the ability to obtain the same building blocks repeatedly and reliably such as composition, block, sequence etc. See Nanotechnology, Nanoscale, and Molecular Manufacturing.