Programmable matter

Programmable matter is matter which has the ability to change its physical properties (shape, density, moduli, conductivity, optical properties, etc.) in a programmable fashion based upon user or automated input.

Applications
In terms of scale, robotic materials use sensors, actuators, computation, reconfigurable by particle motion, and are in the centimeter size range. In the micrometer to sub-millimeter range examples include MEMS-based units, cells created using synthetic biology, and the utility fog. At the nanoscale end there are shape changing molecules and quantum dots (artificial atoms).

Metamaterials
Metamaterials are artificial composites that can be controlled to react in ways that do not occur in nature. For example, a material that can have its index of refraction tuned so that it can have a different index of refraction at different points in the material, could result in an invisibility cloak.

Shape-changing molecules
Molecules that can change their shape, as well as other properties, in response to external stimuli. This was used in later versions of the Terminator.

Electropermanent magnets
They allow creating controllable permanent magnets where the magnetic effect can be maintained without requiring a continuous supply of electrical energy. These programmable magnets can give rise to self-building structures.

Self-reconfiguring modular robotics
SRCMR is a field of robotics in which a group of basic robot modules work together to dynamically form shapes and create behaviours suitable for many tasks, similar to programmable matter. This is important early technology for self-replicating systems.

Claytronics
This concerns reconfigurable nanoscale robots ('claytronic atoms', or catoms) designed to form much larger scale machines or mechanisms. The catoms will be sub-millimeter computers that will eventually have the ability to move around, communicate with other computers, change color, and electrostatically connect to other catoms to form different shapes.

See also:

Computronium