make mechanical structures of much smaller length scales deep in the submicron
range. These efforts have initiated the field of nano-electromechanical systems
(NEMS) [99].
The crucial aspect of NEMS fabricated structures is the realisation that one is
dealing with mechanical vibrations of much higher frequencies. In the case of
MEMS the resonance frequencies of the fabricated structures are in the range
of tens to hundreds of kHz. For NEMS the frequencies are well into the RF range
(1–100 MHz). Such a high frequency mechanical vibration needs investigation of
physical properties (particularly mechanical properties) in a length scale that has
not been done previously.
Interestingly, carbon nanotubes, due to their superior mechanical properties
and their coupling of size and deformation to electronic structures are an exciting
NEMS material. There are investigations of CNT from this viewpoint [100].
The field of NEMS has opened research challenges in the following well defined
yet interdependent areas: (1) the design and fabrication of submicron mechanical
Fig. 21.18. (a) Schematic of the forces involved in
nanomanipulation. (b) The scheme for nanomanipulation.
21.7 Nano-Electromechanical Systems 719