Despite its apparent simplicity, normal muscle control is actually very complex, involving several regions of the brain and spinal
cord. Voluntary movement of a muscle begins when electrical signals are generated in the brain, which then pass to the spinal cord. The spinal cord then sends signals out to the surface of the muscles involved, which
promote physical movement by tightening and relaxing.
It will probably be quite some time in the future before we have perfected the art and science
of robotics, where in its more advanced stages would be able to simulate, if not surpass, our ability to initiate and control motion. On the road to realizing this goal and facilitating many present day
applications, it is quite apparent that the task would become less cumbersome if, through material design and engineering, we were able to efficiently build as much "smartness" into the resulting components as
There are several classes of functional ceramics, polymers, and composites, including metallic that are of
interest and have shown much promise; each being at various stages of development or commercialization. Of great interest are electroactive ceramics (such as piezoelectric and electrostrictive), functional
alloys (shape memory and magnetostrictive), electroactive polymers (conducting, shape memory and elastomeric), and functional composites.