A replicator is an object or organism that can make copies of itself. Examples abound in the biological world; cells are a common example. However, replicators can also be developed in the electromechanical (or mechatronic) realm. This is of interest to researchers in nanotechnology and robotics .
Replicators can exist in either of two forms, known as first-sense and second-sense. A first-sense replicator makes an exact duplicate of itself, including any changes that have occurred in its structure after it was created. A second-sense replicator maks a duplicate of itself as it existed when created. In biology, genes are first-sense replicators, while cells in general are second-sense replicators. First-sense replication is of particular interest, because it allows for the possibility of machine evolution.
A macroscale replicator, also called a clanking replicator, is a robot that can build a copy of itself using conventional materials and parts. Imagine a robot-building factory in which all the workers are robots that build other robots! There might be several different types (species) of robot, each designed for a particular task. Even the factory could, given the right programming of the robots as a team, be duplicated. Science fiction authors have exploited this theme by describing how a small team of robots could be sent to a planet to colonize it. The end result would be a planet with hundreds of robot factories, operated by robot-building robots.
A nanoscale replicator, also called an assembler, is a microscopic, self-duplicating machine with dimensions on the order of billionths of a meter ( nanometer s). Replicators of this type could be programmed to function as antibodies or anti-viral agents designed to attack and destroy specific disease-causing organisms inside the human body. The number of duplications could be controlled by programming, so when all the disease-causing agents were eliminated, the replication process would cease. Research and development efforts involving machines such as this are part of the field of biomechatronics.