Micro-Electro-Mechanical Systems, or MEMS, is a technology that in its most general form can be defined
as miniaturized mechanical and electro-mechanical elements that are made using the techniques of
microfabrication. The critical physical dimensions of MEMS devices can vary from several millimeters to
below one micron. Similarily, the types of MEMS devices can vary from relatively simple structures having
no moving elements, to extremely complex electromechanical systems with multiple moving elements under
the control of integrated microelectronics. The one main criterion of MEMS is that there are at least some
elements having some sort of mechanical functionality whether or not these elements can move. The
miniaturized structures such as sensors, actuators, and microelectronics are the functional elements of
MEMS. Microsensors and microactuators are the main elements which comes under MEMS. Microsensors
and microactuators are appropriately categorized as “transducers”, which are defined as devices that convert
energy from one form to another.
Microsensors- Microsensers are the devices which convert a measured mechanical signal into an electrical
signal. Over the past several decades MEMS researchers and developers have demonstrated an extremely
large number of microsensors for almost every possible sensing modality including temperature, pressure,
inertial forces, chemical species, magnetic fields, radiation, etc. Many of these micromachined sensors have
demonstrated performances exceeding those of their macroscale counterparts. For example, a pressure
transducer usually outperforms a pressure sensor made using the most precise macroscale level machining
techniques. Microsensors not only achieve stellar device performance, but reduce the production cost.
Silicon based discrete microsensors were quickly commercially exploited and the markets for these devices
continue to grow at a rapid rate.
Microatuators- A microactuator is a microscopic servomechanism that supplies and transmits a measured
amount of energy for the operation of another mechanism or system. It includes microvalves for control of
gas and liquid flows, optical switches and mirrors to redirect or modulate light beams, independently
controlled micromirror arrays for displays, microresonators for a number of different applications,
micropumps to develop positive fluid pressures, microflaps to modulate airstreams on airfoils, as well as
many others. Even though these microactuators are extremely small, they frequently can cause effects at the
macroscale level; that is, these tiny actuators can perform mechanical feats far larger than their size would
imply. For example, researchers have placed small microactuators on the leading edge of airfoils of an
aircraft and have been able to steer the aircraft using only these microminiaturized devices.
Microelectronics:- Microelectronics relates to the study and manufacture of very small electronic designs
and components. These devices are typically made from semiconductor materials. Microelectronic
integrated circuits can be thought of as the "brains" of a system and MEMS augments this decision-making
capability with "eyes" and "arms", to allow microsystems to sense and control the environment. Sensors
gather information from the environment through measuring mechanical, thermal, biological, chemical,
optical, and magnetic phenomena. The electronics then process the information derived from the sensors and
through some decision making capability direct the actuators to respond by moving, positioning, regulating,
pumping, and filtering, thereby controlling the environment for some desired outcome or purpose.
Furthermore, because MEMS devices are manufactured using batch fabrication techniques, and can be
placed on a small silicon chip at a relatively low cost. MEMS technology is extremely diverse and fertile,
both in its expected application areas, as well as in how the devices are designed and manufactured. Already,
MEMS is revolutionizing many product categories by enabling complete systems-on-a-chip to be realized.
Nanotechnology- Nanotechnology is the ability to manipulate matter at the atomic or molecular level to
make something useful at the nano-dimensional scale. Basically, there are two approaches in
implementation: the top-down and the bottom-up. In the top-down approach, devices and structures are