Electrostatic assumptions
We assume that the change in energy of the actuator is only due to the
increased capacitance due to the increased length of the zipped region\(l_{e}\left(\alpha\right)\). We neglect the change in the electric
field in the unzipped region (where the dielectric fluid is) when
changing the angle \(\alpha\). We assume ideal dielectrics. We assume
there is no liquid in-between the electrodes in the zipped region (the
two electrodes are only separated by the dielectric film).
As a result, the capacitance of the actuator as a function of \(\alpha\)is