MEMS stands for MicroElectroMechanical Systems. Currently, the word MEMS denotes man-made mechanical elements, sensors, actuators and electronics that that were produced using microfabrication technology and are integrated on a silicon substrate. Increasingly, the word MEMS is used for miniaturized devices that are based on Silicon technology or traditional precision engineering, chemical or mechanical.
NEMS stands for NanoElectroMechanical Systems. NEMS extend miniaturization further toward the ultimate limit of individual atoms and molecules. NEMS are man-made devices with functional units on a length scale between 1 and 100 nm. Some NEMS are based on the movement of nanometer-scale components.
Nanoelectronics extends miniaturization further toward the ultimate limit of individual atoms and molecules. On such a small scale, billions of devices could be integrated into a single nanoelectronical system. Nanoelectronics is often considered a disruptive technology because present candidates for nanoelectronical functional elements are significantly different from traditional transistors.