Nano Electromechanical Systems and Its Applications

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1. ABSTRACT:

Nano electromechanical systems are devices that operate like normal electromechanical devices but are built on the nanoscale or even the atom scale. Controlling and building such devices require advanced technology that is still facing a lot of challenges

2. INTRODUCTION

Nanotechnology is defined by the National Nanotechnology initiative as "understanding and control of matter at dimensions between approximately 1 and 100 nanometers, where unique phenomena enable novel applications. Encompassing nanoscale science, engineering, and technology, nanotechnology involves imaging, measuring, modeling, and manipulating matter at this length scale."

The importance of nanoscale technology is the idea that all properties of material up o the atoms can be used.

Nanoelectromechanical systems, also known as "NEMS", are basically electro mechanical systems such as switches and transistors that are scaled to nano or even atom size [1]. Nanoelectromechanical systems are evolving, with new scientific studies and technical applications. In general, all mechanical devices are shrinking in thickness and width to reduce mass, this is needed to reduce mass and lower the force constants of these systems. The main advantage of Nanoelectromechanical systems is that its flexible properties allow it to access to fundamental frequencies in the microwave range which vary from 0.3GHz to 300GHz. Another advantage is the high mechanical quality factor `Q' which can easily be in the tens of thousands or higher; another advantage is the active masses in the femtogram range which is A unit of mass equal to 10^15 grams and use a simple fg. In addition to this nanoelectromechanical systems have force sensitivities at the attonewton level; mass sensitivity at the level of _individual_ molecules, heat capacities far below a "yoctocalorie" [2].

Even though this science is still growing, it is still under experiments to find methods of build and control such systems with extremely small characteristic parameters.

3. HISTORY OF NEMS

The initial start for small mechanical systems stated in 1950 when Richard Feynman, physicist and part of the Manhattan project [3], issued a public challenge by offering $1,000 for the first perosn that design a electrical motor smaller than 1/64th of an inch. The winner was William McLellan whose motor was 250-microgram 2000-rpm motor consisted of 13 separate parts, see figure 1[4].

Figure 1, McLellan Motor vs. Pin Head

The main start of this technology was the field of micro-electromechanical systems (MEMS), which became firmly established in the 1980s. Motors built under this field are hundreds times smaller than the motor than McLellan's motor. MEMS also have matured enough to reach the production lines in products such as digital projectors that contain millions of electrically driven micro-mirrors to micro scale motion sensors used to deploy airbags. The main benefit of MEMS is the low cost of production which allow for both mass production and mass usage by scientists to provide an a lot of information about our physical surroundings starting in the sea all the way to the far space.

MEMS also helped to connect between semiconductors and mechanical engineering for application on a very small scale. A sample system that used MEMS was the Microfabrica's EFAB system which was the first MEMS foundry process to accept CAD files as input, turning customer designs into micro-machines much faster than traditional methods. EFAB builds the devices one metal layer at a time. In this image, the square at the top is a micro-fluidics device with internal passageways used for a "lab on a chip." The multi-arm device (center) is a fuel injection nozzle. Bottom left is an accelerometer, and bottom right is an inductor used in RF circuits. See figure 2 for the Microfabrica's EFAB system.

The main challenges facing MEMS is adhesion or bonding. This happens when one moving part of the...
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