2. It statnds for micro electro mechanical
It is the integration of elements sensors
actuators and electronics on a common
Micro fabrication technology for making
3. The actuator is an element which
applies a force to some object
through a distance
Various actuation mechanisms :
1. Electrostatic actuation.
2. Thermal actuation.
3. Piezoelectric actuation.
4. Magnetic actuation.
5. A voltage is applied between metal plates to
induce opposite charges and coulomb
6. Electrostatic micro-actuator consist of many
fingers that ate actuated by applying a
The thickness of the fingers is small in
comparison to their length and width.
The attractive forces are mainly due to the
fringing fields rather than the parallel plate
8. Low power dissipation.
Can be designed to dissipate no power while
exerting a force.
High power density at micro scale.
Easy to fabricated
Noise & efficiency
Range of force, motion and frequency
11. Assume that the electrical field is uniform
between the plates of the capacitor and zero
Uniform electric field between the plates has
Voltage across the capacitor is the product of
E-field and the gap.
The capacitance is the ratio of the charge and
12. When the capacitor plates are fixed the stored
energy is given by :
Fixed gap – increasing charge
13. At zero gap, the electrical energy is zero.
The force between two plates with opposite charges
+Q and –Q depends on electric fields setup by
The field is : ɛ=Q/ɛA
The corresponding force is :
Now we pull upper plate by distance g
Charge fixed – increasing gap
15. Micro pumps play a significant role in micro
fluid systems of MEMS.
Micro pumps were started in middle 1980s.
Before 1990s, mechanical pumps were mainly
studied. After 1990s, non-mechanical pumps
Presently most micro pumps aim to fluid