A nanomachine, also called a nanite, is a mechanical or electromechanical device whose dimensions are measured in nanometers (millionths of a millimeter, or units of 10 -9 meter).
Nanomachines are largely in the research-and-development phase, but some primitive devices have been tested. An example is a sensor having a switch approximately 1.5 nanometers across, capable of counting specific molecules in a chemical sample. The first useful applications of nanomachines will likely be in medical technology, where they could be used to identify pathogens and toxins from samples of body fluid. Another potential application is the detection of toxic chemicals, and the measurement of their concentrations, in the environment.
The microscopic size of nanomachines translates into high operational speed. This is a result of the natural tendency of all machines and systems to work faster as their size decreases. Nanomachines could be programmed to replicate themselves, or to work synergistically to build larger machines or to construct nanochips. Specialized nanomachines called nanorobots might be designed not only to diagnose, but to treat, disease conditions, perhaps by seeking out invading bacteria and viruses and destroying them.
Another advantage of nanomachines is that the individual units require only a tiny amount of energy to operate. Durability is another potential asset; nanites might last for centuries before breaking down. The main challenge lies in the methods of manufacture. It has been suggested that some nanomachines might be grown in a manner similar to the way plants evolve from seeds.