We provide sufficient conditions for the existence of periodic solutions for an idealized electrostatic actuator modeled by the Liénard-type equation
x
¨
+
F
D
x
,
x
̇
+
x
=
β
V
2
t
/
1
−
x
2
,
x
∈
−
∞
,
1
with
β
∈
ℝ
+
,
V
∈
C
ℝ
/
T
ℤ
, and
F
D
x
,
x
̇
=
κ
x
̇
/
1
−
x
3
,
κ
∈
ℝ
+
(called squeeze film damping force), or
F
D
x
,
x
̇
=
c
x
̇
,
c
∈
ℝ
+
(called linear damping force). If
F
D
is of squeeze film type, we have proven that there exists at least two positive periodic solutions, one of them locally asymptotically stable. Meanwhile, if
F
D
is a linear damping force, we have proven that there are only two positive periodic solutions. One is unstable, and the other is locally exponentially asymptotically stable with rate of decay of
c
/
2
. Our technique can be applied to a class of Liénard equations that model several microelectromechanical system devices, including the comb-drive finger model and torsional actuators.