1. Micro-Electro-Mechanical System
ELECTROSTATICALLY
ACTUATED CANTILEVER BEAM
By-Vedavyas P.Burli

2. Introduction
• Elastic cantilever beam is an elementary structure in
MEMS design.
• The electro mechanics interface to solve the coupled
equations for the structural deformation and the
electric field. Such structures are frequently tested by
means of a low frequency capacitance voltage sweep.
• The bending of a beam due to electrostatic forces.

4. Model definition
• The dimensions of the
beam are: Length: 300
μm; Width: 20 μm; and
Thickness 2 μm.
• The beam is made of
polysilicon with a
Young’s modulus, E, of
153 GPa, and a
Poisson’s ratio, ν, of
0.23.,
• It is fixed at one end but
is otherwise free to
move.
• The polysilicon is
assumed to be heavily
doped, so that electric
field penetration into the
structure can be
neglected.

13. Result and discussion
• There is positive feedback
between the electrostatic forces
and the deformation of the
cantilever beam.
• This action, in turn, increases
the forces. At a certain voltage
the electrostatic forces
overcome the stress forces, the
system becomes unstable, and
the gap collapse

14. References
• R.K. Gupta, Electrostatic Pull-In Structure Design for In-Situ Mechanical
Property Measurements of Microelectromechanical Systems (MEMS),
Ph.D. thesis, MIT, 1997.
• Methodologies.V Vardhan K.J.Vinoy,S.Gopalkrishnan,Wiley.Smart Material
systems and MEMS design and development
• Model gallery,COMSOL Multiphysics 4.3