The ratio of the volume to the surface area of a surface has length dimension and is a representative of the system’s length scale.
Length scale [m]= Volume [m3] / Surface area [m2]
For systems in micro and nano scales this ratio is 10-6 and 10-9 m, respectively. This simple calculation shows the importance of surface comparing to volume in small scale.
In all small worlds around us, building blocks are not voluminous, they have large exposed surfaces in contrast. Due to the importance of the surface all phenomena related to the surface are more pronounced in the small scales. One of these phenomena is surface adhesion including the adhesion of contaminations to the surfaces. This contaminations change all surface properties and cause a huge error in the experiments. Due to this reason we need to take extra care about contamination when we are working in small scale comparing to the large systems. Here is what my undergraduate, Min, is saying about contamination in small scale:
In this lab, the experiments are sensitive to the contamination. The contamination could be referred to as presence of unwanted substances that could affect the results of an experiment. Compared to the small system, the presence of contamination has less impact to the large system, where volume is the main concern. However, the contaminations often become a main issue to the small system, where the surfaces are mainly concerned than volume. Thus, in micro manufacturing process, careful procedures are followed to reduce the amount of the contaminations present.