Ionomeric polymer metal composites can be used as transducers characterized by high strain
and low force. They are created by bonding a thin conductive electrode to the surfaces
of an ionomeric polymer. Much of the work in the past has focused on using a voltage
across the thickness of the polymer to produce mechanical motion. That work has often
demonstrated that the mechanism of transduction within the polymer was associated with
the accumulation of charge in the polymer. This thesis will discuss the use of current as
a means to better control the accumulation of charge. Better control of the charge will
provide more reliable control of the mechanical motion of the polymer.
The data presented in this thesis demonstrates that the response of an ionomeric
polymer to a current input is repeatable. The repeatability is a desirable result; however,
using current to actuate the polymers also produces back relaxation in the response. Examination
of the back relaxation reveals a low frequency non-linearity. The nonlinearity is
quantified by the fact that the gain associated with the back relaxation does not increase
linearly with an increase in input current. There is also a change in the response at certain
voltage thresholds. For example, when the voltage across the polymer exceeds 3 V, the
rate of back relaxation increases. The repeatability of the response will aid in implementing
reliable control of the polymer, but the non-linearities in the back relaxation will provide a
considerable challenge in developing a model to be used in control.
