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Reducing floor vibration is essential for patterning and imaging industries that work at the sub-nanometre level. As experts move towards smaller scales for pin-point accuracy and more sophisticated solutions, the need for vibration damping and acoustic dampening solutions is now more than ever.

A number of instruments need to achieve extremely precise measurements and the highest of resolutions. For example, electron microscopes need resolutions that range from the sub-nanometer to the tens of nanometres. Yet other microscopes work with resolutions in the sub-Angstrom levels. Floor vibration often causes a hindrance for these tools as it prevents them from achieving their design specifications.

The Quiet Building Concept and its Limitations

To overcome such issues, architects bank on the concept of ‘quiet buildings’, where Vibration dampening and acoustic dampening materials are used to reduce vibration levels without causing too many complexities in design. However, while these buildings offer moderate vibration damping solutions, nano-tech facilities generally need to meet extremely low vibration specification levels, and this significantly increases the cost of constructing the facility.

Another hindrance to the concept of ‘quiet buildings’ is that even though the floors are made using Vibration damping material, the moment you add other machinery and people into the building, vibration negates any benefit that the quiet building design has to offer.

The Quiet Island Concept

New data shows that creating quiet islands at several locations within the facility can truly help the facility achieve the low vibration requirement of nano-tech facilities. The concept focuses on placing a damped, rigid platform that matches the footprint left by the instrument and is ably supported by active acoustic dampening and vibration cancelling systems at locations where precision instruments are located and in locations where experiments and research is expected to be conducted. To do so, architects replace a section of the access floor with an isolated foundation that has been mounted to the sub-floor in order to prevent sub-floor vibrations from reaching the devices.

Benefits of Creating a Quiet Island

One of the main benefits of creating quiet islands is that the technique offers an extremely quiet surface, thereby creating a mini-environment, oases within the facility that are free of vibration. It becomes easier to make these quiet islands meet the cleanliness requirement of nano-tech facilities and rather on focusing on clean rooms and vibration proof rooms, the focus soon turned to clean islands and vibration proof islands, thereby reducing costs and increasing efficiency.

The quiet island concept also helps overcome the vibration caused when people and machinery are introduced into the facility. The approach is to arrange low frequency inertial vibration sensors in 3 axes in order to determine the level of vibration. The signals pass through advanced controllers and high capacity piezoelectric actuators to prevent any floor motion from reaching the isolated surfaces of the quiet island.

The quiet island concept comes as a boon to advanced semiconductor factories and chip-makers. Researchers at advanced electron microscope and imaging centres and nanotechnology research centres can also benefit from the quiet island concept.

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