Nanomaterials
_Fundamental Concept_
_Size Concerns_
_Materials Used_
_Chemical Processing of Ceramics_

Another concern is that the volume of an object decreases as the third power of its linear dimensions, but the area only decreases as its second power. This somewhat subtle and unavoidable principle has enormous consequences. For example, the power of a drill (or any other machine) is proportional to the quantity, while the friction of the drill's bearings and gears is proportional to their area. For a normal-size drill, the power of the device is enough to handily overcome any friction. But scaling down its length by a factor of 1000, for example, decreases its power by 10,003 (a figure of one billion) and reduce the friction by only 10,002 (a figure of "only" one million). Proportionately it has 1000 times less power per friction than the original drilling. When the original skid-to-power ratio was, say, 1%, which means less drilling will have 10 times as much friction as a force. Drill is useless.

For this reason, while super-miniature electronic products, integrated circuits are fully functional, the same technology can not be used to make working mechanical devices than the rates in which friction forces are beginning to exceed the available power. Although you can see microphotographs of delicately etched silicon gears, these devices are little more than curiosities with limited real world, for example in moving mirrors and shutters. The surface tension increases at roughly the same way, so magnifying the tendency for very small objects to stick together. This could possibly make any kind of "micro-factory" impractical: even if the robotic arms and hands can be scaled down, something they pick up will tend to be impossible to put down. The above being said, molecular evolution has resulted in working ciliary flag ella, muscle fibers and rotary engines in aqueous environments, all on the nanoscale. These machines take advantage of the increased frictional forces exist at the micro or nano scale. Unlike a bat or a propeller, which depends on the normal friction forces (friction forces perpendicular to the surface) to achieve momentum ciliary movement develop from excessive drag or laminar forces (frictional forces parallel to the surface) present on the micro-and nano. To build a meaningful "machines" at the nano level, the forces must be considered. We are faced with the development and design of intrinsically safe machinery rather than the simple representations of macroscopic them.

All scaling issues must be assessed carefully when evaluating nanotechnology for practical applications.