Chemotaxis and Chemokinesis of Living and Non-living Objects

One of the fundamental properties of living organisms is the ability to sense and respond to changes in their environment by movement. If a motile cell senses soluble molecules and follows along a concentration gradient to the source, or if it moves away from a source of undesirable chemicals, e.g. repellent, toxin, it is displaying a directional movement called positive or negative chemotaxis, respectively. This phenomenon is well-known to biologists and intensively studied in living systems. In contrast chemokinesis is a change in movement due to environmental input but the resulting movement is non-vectorial and can be considered directionally random. Recently, in the last ten years, few laboratories started to focus on the movement properties of artificial constructs, including the directional movement of non-living objects in chemical gradients. This chapter will focus on chemotaxis and chemokinesis of natural and synthetic systems that may provide chemical platforms for unconventional computing.