Three MEMS devices described below are:
I. Eco Scan MEMS resonant mirror: MEMS resonant mirror devices have the potential to miniaturize optical systems, such as sensors, displays and printing devices. They integrate the driving actuator into the mirror structure, a small, low power consumption and inexpensive device. The Eco scan MEMS resonant mirror uses the electromagnetic drive method. On a single crystal silicon substrate, a mirror, torsion bars and coils are formed and permanent magnets are placed on the periphery of those parts. In the magnetic field of the permanent magnets, when current is applied to the coil, Lorentz force is generated on the coil and thereby the mirror tilts to the position where the rotational torque of the coil is balanced by the restoring forces of the torsion bars. Lorentz force is proportional to the current by changing the intensity of the current the tilt angle of the mirror can be changed. With alternating current matching to the resonant frequency large amplitude of current obtained with low power consumption. 
II. Capacitive type gyro sensor: A capacitive type gyro sensor is a second generation ring vibrating gyro which consists of a glass-silicon-glass structure with silicon bulk micromachining. Capacitive transducer for the drive and detection is implemented by electrodes arranged in the oscillation plane and fabricated by a wafer process using planar photolithography and DRIE (Deep reactive-ion etching).The resonator of the sensor is made from single-crystal silicon wafer which is kept in vacuum package. 
III. MEMS variable optical attenuator: The variable optical attenuator (VOA) is an indispensable component in fiber-optic communication network systems. Large numbers of VOA components are used in the wavelength division multiplexing (WDM) system. VOAs are also used to tune the light intensity from laser diodes to fiber amplifiers and to photo detectors. The role of VOA is to maintain the quality of fiber-optic communication to suppress the bit error rate by adjusting the intensity of travelling light in the appropriate range so that the optoelectronic devices function with their optimum performance. 
Fabrication processes are developed to create MEMS devices at ever decreasing sizes. As the size get decreased, different physical forces comes into picture and also their importance depending on the nature. These changes dictate how device must build and what forces it will use to operate. This issue is called scaling. 
I. Miniaturization helps in batch fabrication at lower cost per device with less energy consumption and less material consumed.
II. With reduction in size can take advantage of different scaling laws such as electrostatic forces and also break down of macroscale laws of physics.
III. Performance wise, integration with circuitry can reduce noise and improve sensitivity. Yield and reliability may be improved with fewer defects per chip. 
VOLETI SHYAM KUMAR...