Electronic
Products - October 2007
New form of isolation may aid nanotechnology
development
Richard Coinerford
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The minuteness of nano-devices makes it necessary to
isolate them and their surrounding test equipment from
vibration. Unfortunately, the cost of commonly used
active vibration isolators can overtax a start-up R&D
labs' budget. Hence, one may find atomic force microscopes
suspended by bungee cords in some labs.
Because their cost can be about one-third that of active
systems, negative-stiffness vibration isolation systems
invented by David L. Platus of Minus K Technology promise
to solve this problem. Whereas active isolation uses
electronics to sense the motion and put out equal amounts
of energy to cancel vibration, negative-stiffness isolators
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A system like the above based on negative-stiffness
vibration-isolation cost about one-third as much an
active vibration cancellation system.
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Vertical-motion isolation is provided by a stiff spring that
supports a weight load, combined with a negative-stiffness
mechanism. The net vertical stiffness is very low without
affecting the spring's static load-supporting capability.
Beam-columns connected in series with the vertical-motion
isolator provide horizontal isolation.
The result is a compact passive isolator capable of very
low vertical and horizontal natural frequencies. The isolators
(adjusted to 1/2 Hz) achieve 93% isolation efficiency at 2
Hz; 99% at 5 Hz; and 99.7% at 10 Hz. For more information,
contact Steve Varma at Minus K Technology 310-348-9656; or
visit www.minusk.com employ a completely mechanical approach.
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