Carbon Nanotubes (CNT) are intensively studied as a new functional material for sensors, nanosystems and electronic systems. Single-walled carbon nanotubes (SWNTs) for example show unique mechanical and electromechanical properties and they change electronic properties by interacting with the environment (e.g. for chemical and biochemical sensing). Therefore CNTs are very promising candidates for active elements in future nanoscaled transducers. Concepts for carbon nanotube sensors for mechanical and chemical quantities are presented. We focus on single-walled carbon nanotubes as "simple" macro molecular functional structures with an option for low scale integration in micro and nano electromechanical systems (MEMS and NEMS).