08-01-2010, 06:07 PM
Nanoelectromechanical systems, or NEMS, are MEMS scaled to submicron dimensions. it is possible to attain extremely high fundamental frequencies while preserving very high mechanical responsivity. their extreme surface-to-volume ratios, and their unconventional characteristic range of operation are a challenge. ultrasensitive, very high bandwidth displacement transducers; an
unprecedented control of surface quality and adsorbates; novel
modes of efficient actuation at the nanoscale are all realisable with this technology.
Introduction
They have characters like fundamental frequencies in the microwave range; Qâ„¢s, i.e.
mechanical quality factors, in the tens of thousandsactive masses in the femtogram range; force
sensitivities at the attonewton level; mass sensitivity at the level of
individual molecules, heat capacities far below a yoctocalorie.
MULTITERMINAL MECHANICAL DEVICES
multiterminal electromechanical devices with two or more ports are possible mechanical
transducers provide input stimuli (i.e. signal forces), and read out a
mechanical response. either quasi-static or time-
varying electric signals can be applied, and then converted by the
control transducers into quasi-static or time-varying forces to
induce mechanical
reaction to perturb the properties of the mechanical element in a controlled,
manner.
NEMS Attributes
1) frequency:
Nanodevices in this ultimate limit will have resonant frequencies in
the THz range, which is the characteristic of molecular vibrations.
2)Quality Factor.
The Qâ„¢s attained for NEMS in are in the range from 10^3 to 10^5. . This
small degree of internal dissipation (D=1/Q) impart to NEMS their
low operating power levels and high attainable force sensitivity.
The Q's are much greater than the electrical resonators.
3)opertaing power level:
the total system power levels still are onlyof order 1 microWatt This is six orders of magnitude smaller than powerdissipation in current systems of similar complexity based upondigital devices that work solely in the electrical domain.
4)Available Dynamic Range
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